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WO2013042555A1 - Spark plug, ignition device and method for igniting air-fuel mixture - Google Patents

Spark plug, ignition device and method for igniting air-fuel mixture Download PDF

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Publication number
WO2013042555A1
WO2013042555A1 PCT/JP2012/072895 JP2012072895W WO2013042555A1 WO 2013042555 A1 WO2013042555 A1 WO 2013042555A1 JP 2012072895 W JP2012072895 W JP 2012072895W WO 2013042555 A1 WO2013042555 A1 WO 2013042555A1
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WO
WIPO (PCT)
Prior art keywords
electrode
exposed portion
spark plug
insulator
embedded
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2012/072895
Other languages
French (fr)
Japanese (ja)
Inventor
尚博 清水
昭二 横井
下田　健二朗
隆太 河野
貴 江上
田中　克典
亘 塩野谷
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NGK Insulators Ltd
Original Assignee
NGK Insulators Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by NGK Insulators Ltd filed Critical NGK Insulators Ltd
Publication of WO2013042555A1 publication Critical patent/WO2013042555A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/46—Sparking plugs having two or more spark gaps
    • H01T13/462—Sparking plugs having two or more spark gaps in series connection
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
    • H01T13/22—Sparking plugs characterised by features of the electrodes or insulation having two or more electrodes embedded in insulation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P13/00—Sparking plugs structurally combined with other parts of internal-combustion engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P3/00—Other installations
    • F02P3/06—Other installations having capacitive energy storage

Definitions

  • the present invention relates to a spark plug, an ignition device, and a method for igniting an air-fuel mixture.
  • a typical spark plug includes a high-voltage electrode and a ground electrode. A high voltage is applied between the high voltage electrode and the ground electrode, and an arc discharge is generated in the gap between the high voltage electrode and the ground electrode.
  • a floating electrode (floating electrode 11) is provided in addition to a high-voltage electrode (center electrode 3) and a ground electrode (outer electrode 6 and ground electrode 8). A high voltage is applied between the high voltage electrode and the ground electrode, and a discharge is generated in the gap between the high voltage electrode and the floating electrode.
  • Patent Document 1 describes that a floating electrode is brought close to a high voltage electrode (paragraph 0015). Patent Document 1 describes that the capacitance between the high-voltage electrode and the floating electrode is 10 pF or more, and the capacitance between the floating electrode and the ground electrode is 3 pF or more. In Patent Document 1, the magnitude relationship between the former capacitance and the latter capacitance is unknown.
  • An object of the present invention is to provide an ignition plug, an ignition device, and a method for igniting an air-fuel mixture that can stably ignite the air-fuel mixture even under difficult combustion conditions and reduce energy consumption.
  • the first to seventh aspects of the present invention are directed to the spark plug.
  • an insulator, a high voltage electrode, a ground electrode, and a floating electrode are provided.
  • the high-voltage electrode includes a first exposed portion and a first embedded portion.
  • the floating electrode includes a second exposed portion and a second embedded portion. The first exposed portion and the second exposed portion are exposed to the outside of the insulator. The first embedded portion and the second embedded portion are embedded in the insulator. The second exposed portion is relatively close to the first exposed portion, and the ground electrode is relatively far from the first exposed portion.
  • the capacitance between the high voltage electrode and the floating electrode is relatively small.
  • the capacitance between the floating electrode and the ground electrode is relatively large.
  • the second aspect of the present invention adds further matters to the first aspect of the present invention.
  • an accommodation space is formed in the ground electrode.
  • An insulator is provided with the to-be-accepted part accommodated in accommodation space.
  • the second embedded portion includes a structure embedded in the accommodated portion.
  • the accommodation space is inside the round hole.
  • the inner peripheral surface of the round hole goes around the structure.
  • the structure is a tube-shaped part.
  • the outer peripheral surface of the tube-shaped portion is opposed to the inner peripheral surface of the round hole.
  • the fourth aspect of the present invention adds further matters to any one of the first to third aspects of the present invention.
  • a hollow space is formed in the insulator.
  • the first embedded portion includes a hollow holding portion that is hollowly held inside the hollow space.
  • the fifth aspect of the present invention adds further matters to the first aspect of the present invention.
  • an accommodation space is formed in the ground electrode.
  • An insulator is provided with the protrusion part which protrudes outside the accommodation space. The first exposed portion and the second exposed portion further protrude from the protruding portion.
  • the sixth aspect of the present invention adds further matters to any one of the first to fifth aspects of the present invention.
  • the first exposed portion and the second exposed portion have a first rod tip and a second rod tip, respectively.
  • the seventh aspect of the present invention adds further matters to any one of the first to sixth aspects of the present invention.
  • two or more floating electrodes are insulated from each other.
  • the eighth aspect of the present invention is directed to an ignition device.
  • the spark plug and the pulse voltage application mechanism of the first aspect of the present invention are provided.
  • the pulse voltage application mechanism applies a pulse voltage between the high voltage electrode and the ground electrode.
  • the ninth aspect of the present invention is directed to a method for igniting an air-fuel mixture.
  • a spark plug according to the first aspect of the present invention is prepared.
  • a pulse voltage is applied between the high-voltage electrode and the ground electrode, and streamer discharge is generated between the first exposed portion and the second exposed portion.
  • the tenth to sixteenth aspects of the present invention are directed to the spark plug.
  • an insulator, a high voltage electrode, a ground electrode, and a floating electrode are provided.
  • the ground electrode includes a first exposed portion.
  • the high voltage electrode includes a first embedded portion.
  • the floating electrode includes a second exposed portion and a second embedded portion. The first exposed portion and the second exposed portion are exposed to the outside of the insulator. The first embedded portion and the second embedded portion are embedded in the insulator. The second exposed portion is relatively close to the first exposed portion.
  • the high voltage electrode is relatively far from the first exposed portion.
  • the capacitance between the high voltage electrode and the floating electrode is relatively large.
  • the capacitance between the floating electrode and the ground electrode is relatively small.
  • the eleventh aspect of the present invention adds further matters to the tenth aspect of the present invention.
  • the first embedded portion includes a first structure.
  • the second embedded portion includes a second structure.
  • An internal space is formed in the second structure.
  • An insulator is provided with the to-be-filled part with which internal space is filled.
  • the first structure is embedded in the portion to be filled.
  • the first structure is a bar-shaped portion.
  • the second structure is a tube-shaped part. The tube-shaped portion goes around the rod-shaped portion.
  • the thirteenth aspect of the present invention adds further matters to any of the tenth to twelfth aspects of the present invention.
  • an accommodation space is formed in the ground electrode.
  • the insulator includes a hollow holding portion that is hollowly held inside the accommodation space.
  • the fourteenth aspect of the present invention adds further matters to the tenth aspect of the present invention.
  • an accommodation space is formed in the ground electrode.
  • An insulator is provided with the to-be-accepted part accommodated in accommodation space.
  • the second exposed portion protrudes outside the accommodated portion and protrudes outside the accommodation space.
  • the fifteenth aspect of the present invention adds further matters to any of the tenth to fourteenth aspects of the present invention.
  • the second exposed portion has a rod tip.
  • the sixteenth aspect of the present invention adds further matters to any of the tenth to fifteenth aspects of the present invention.
  • two or more floating electrodes are insulated from each other.
  • the seventeenth aspect of the present invention is directed to an ignition device.
  • the spark plug and pulse voltage application mechanism of the tenth aspect of the present invention are provided.
  • the pulse voltage application mechanism applies a pulse voltage between the high voltage electrode and the ground electrode.
  • the eighteenth aspect of the present invention is directed to a method for igniting an air-fuel mixture.
  • a spark plug according to the tenth aspect of the present invention is prepared.
  • a pulse voltage is applied between the high-voltage electrode and the ground electrode, and streamer discharge is generated between the first exposed portion and the second exposed portion.
  • the nineteenth aspect of the present invention is directed to a spark plug.
  • an insulator, a high voltage electrode, a ground electrode, a floating electrode, and a capacitor are provided.
  • the high voltage electrode includes a first exposed portion and an embedded portion.
  • the floating electrode includes a second exposed portion. The first exposed portion and the second exposed portion are exposed to the outside of the insulator. The buried part is buried in the insulator.
  • the floating electrode has a first capacitance between the high-voltage electrode.
  • the floating electrode has a second electrostatic capacitance between the floating electrode and the ground electrode.
  • the second exposed portion is relatively close to the first exposed portion.
  • the ground electrode is relatively far from the first exposed portion.
  • One terminal of the capacitor is electrically connected to the floating electrode.
  • the other terminal of the capacitor is electrically connected to the ground electrode.
  • the capacitor has a third capacitance. The sum of the second capacitance and the third capacitance is larger than the first capacitance.
  • the capacitor is externally
  • the first to ninth aspects of the present invention when a voltage is applied between the high voltage electrode and the ground electrode, a high voltage is induced between the high voltage electrode and the floating electrode. A powerful streamer discharge is generated between the first exposed portion and the second exposed portion. The discharge volume increases, and the air-fuel mixture can be ignited stably even under difficult combustion conditions. In addition, the current flowing through the spark plug is reduced. Energy consumption per unit discharge volume is reduced.
  • the floating electrode and the ground electrode are opposed to each other across the insulator over a wide range.
  • the capacitance between the floating electrode and the ground electrode is increased.
  • the range in which the floating electrode and the ground electrode are opposed to each other is widened, and the capacitance between the floating electrode and the ground electrode is increased.
  • the high voltage electrode is surrounded by the air gap inside the insulator, and the capacitance between the high voltage electrode and the floating electrode is reduced.
  • the first exposed portion and the second exposed portion are separated from the ground electrode.
  • a discharge is less likely to occur between the first exposed portion and the ground electrode, and a discharge is less likely to occur between the second exposed portion and the ground electrode.
  • the electric field concentrates on the first exposed portion and the second exposed portion, and electric discharge is likely to occur between the first exposed portion and the second exposed portion.
  • the potentials of two or more floating electrodes are independent. Even if a discharge occurs between the high-voltage electrode and one floating electrode, the discharge between the high-voltage electrode and another floating electrode is not hindered, and a multipoint discharge is likely to occur.
  • a high voltage is induced between the floating electrode and the ground electrode when a voltage is applied between the high voltage electrode and the ground electrode.
  • a powerful streamer discharge is generated between the first exposed portion and the second exposed portion.
  • the discharge volume increases, and the air-fuel mixture can be ignited stably even under difficult combustion conditions.
  • the current flowing through the spark plug is reduced, and the energy consumption per unit discharge volume is reduced.
  • the high voltage electrode and the floating electrode are opposed to each other across the insulator over a wide range.
  • the capacitance between the high voltage electrode and the floating electrode is increased.
  • the range in which the center electrode and the floating electrode face each other is widened, and the capacitance between the center electrode and the ground electrode is increased.
  • the insulator is surrounded by the air gap inside the accommodation space, and the capacitance between the floating electrode and the ground electrode is reduced.
  • the second exposed portion is separated from the high voltage electrode, and it is difficult for discharge to occur between the high voltage electrode and the second exposed portion.
  • the second exposed portion is separated from the ground electrode, and discharge is less likely to occur between the second exposed portion and the ground electrode.
  • the electric field concentrates on the second exposed portion, and electric discharge is likely to occur between the first exposed portion and the second exposed portion.
  • the potentials of two or more floating electrodes are independent, and even if a discharge occurs between one floating electrode and the ground electrode, Is not hindered, and multi-point discharge is likely to occur.
  • the nineteenth aspect of the present invention when a voltage is applied between the high voltage electrode and the ground electrode, a high voltage is induced between the high voltage electrode and the floating electrode. A powerful streamer discharge is generated between the first exposed portion and the second exposed portion. The discharge volume increases, and the air-fuel mixture can be ignited stably even under difficult combustion conditions. In addition, the current flowing through the spark plug is reduced. Energy consumption per unit discharge volume is reduced.
  • the first embodiment relates to a spark plug, an ignition device, and a method for igniting an air-fuel mixture.
  • the schematic diagram of FIG. 1 schematically shows the ignition device and the combustion container of the first embodiment.
  • the schematic diagram of FIG. 2 is a perspective view of the ignition plug of the first embodiment.
  • the schematic diagram of FIG. 3 is a cross-sectional view of the spark plug of the first embodiment.
  • the schematic diagram of FIG. 4 is an exploded perspective view of the insulator of the first embodiment.
  • the schematic diagram of FIG. 5 is a perspective view of the floating electrode of the first embodiment.
  • the ignition device 1000 includes an ignition plug 1010 and a pulse voltage application mechanism 1012.
  • the spark plug 1010 is attached to the combustion container 9000.
  • a combustion chamber 9002 is formed in the combustion container 9000.
  • Combustion chamber 9002 is filled with an air-fuel mixture.
  • the spark plug 1010 includes an insulator 1020, a center electrode 1022, a metal shell 1024, and a floating electrode 1026.
  • the center electrode 1022 includes an exposed portion 1030 and an embedded portion 1032.
  • the floating electrode 1026 includes an exposed portion 1040 and an embedded portion 1042.
  • the embedded portion 1032 of the center electrode 1022 is provided to insulate the center electrode 1022 to which a high voltage is applied.
  • the embedded portion 1042 of the floating electrode 1026 is provided to increase the capacitance C2 between the floating electrode 1026 and the metal shell 1024.
  • the pulse voltage application mechanism 1012 applies a pulse voltage between the center electrode 1022 and the metal shell 1024.
  • a high voltage is applied to the center electrode 1022, and the center electrode 1022 becomes a high voltage electrode.
  • the metal shell 1024 is grounded and becomes a ground electrode.
  • the exposed portion 1040 of the floating electrode 1026 is relatively close to the exposed portion 1030 of the center electrode 1022, and the metal shell 1024 is relatively far from the exposed portion 1030 of the center electrode 1022.
  • the capacitance C1 between the center electrode 1022 and the floating electrode 1026 is relatively small, and the capacitance C2 between the floating electrode 1026 and the metal shell 1024 is relatively large.
  • the discharge volume of powerful streamer discharge is large. For this reason, when the air-fuel mixture is ignited by strong streamer discharge, the air-fuel mixture can be stably ignited even under difficult combustion conditions such as when lean combustion is performed. Further, when the air-fuel mixture is ignited by strong streamer discharge, the current flowing through the spark plug 1010 is reduced as compared with the case where the air-fuel mixture is ignited by arc discharge. For this reason, when the air-fuel mixture is ignited by a powerful streamer discharge, the energy consumption per unit discharge volume is reduced.
  • FIG. 6 shows the positional relationship of the electrodes of the first embodiment.
  • the exposed portion 1040 of the floating electrode 1026 is relatively close to the exposed portion 1030 of the center electrode 1022, and the metal shell 1024 is relatively far from the exposed portion 1030 of the center electrode 1022. Accordingly, the discharge path length L1 from the exposed portion 1040 of the floating electrode 1026 to the exposed portion 1030 of the center electrode 1022 via the combustion chamber 9002 is relatively short, and the center electrode 1022 passes from the metal shell 1024 via the combustion chamber 9002.
  • the discharge path length L2 to the exposed portion 1030 is relatively long, and L1 ⁇ L2 is established.
  • the discharge gap between the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026 is narrower than the discharge gap between the exposed portion 1030 of the center electrode 1022 and the metal shell 1024. For this reason, a discharge is relatively unlikely to occur between the exposed portion 1030 of the center electrode 1022 and the metal shell 1024. Further, a discharge is relatively easily generated between the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026.
  • the floating electrode 1026 is disposed between the center electrode 1022 and the metal shell 1024 as shown in FIGS.
  • the center electrode 1022 is on the center axis of the spark plug 1010, and the metal shell 1024 surrounds the center electrode 1022.
  • the floating electrode 1026 is installed between the center electrode 1022 and the metal shell 1024, and the floating electrode 1026 is separated from the center electrode 1022 and the metal shell 1024.
  • the floating electrode 1026 overlaps the center electrode 1022 when viewed from the axial direction of the spark plug 1010, the center electrode 1022 and the floating electrode 1026 are separated from each other in the axial direction of the spark plug 1010.
  • the floating electrode 1026 overlaps the metallic shell 1024 when viewed from the axial direction of the spark plug 1010, the floating electrode 1026 and the metallic shell 1024 are separated from each other in the axial direction of the spark plug 1010.
  • FIG. 7 shows an equivalent circuit of the spark plug of the first embodiment.
  • the voltages V1 and V2 are expressed by equations (1) and (2), respectively.
  • the voltage V1 between the central electrode 1022 and the floating electrode 1026 is It can be derived from the equations (1) and (2) that the voltage V2 between the floating electrode 1026 and the metal shell 1024 is high and low. Therefore, when C1 ⁇ C2 is satisfied, V2 ⁇ V1 is satisfied, and when a pulse voltage is applied between the center electrode 1022 and the metal shell 1024, a high voltage is generated between the center electrode 1022 and the floating electrode 1026. Induced.
  • the electrostatic capacity C2 is at least larger than the electrostatic capacity C1, and preferably 10 times or more of the electrostatic capacity C1.
  • FIGS. 8 and 9 show waveforms of the voltage V between the center electrode 1022 and the metal shell 1024 and the voltage V2 between the floating electrode 1026 and the metal shell 1024.
  • FIG. 8 shows a waveform before discharge.
  • FIG. 9 shows the waveform after discharge.
  • the presence or absence of occurrence of discharge is identified by the voltages V and V2.
  • the presence or absence of occurrence of discharge may be identified by photographing the tip end side of the spark plug 1010 in the axial direction with a camera.
  • the current i flowing through the spark plug 1010 is expressed by the equation (3).
  • the current i is composed of the capacitance C1 between the center electrode 1022 and the floating electrode 1026 and the combined capacitance C2 between the floating electrode 1026 and the metal shell 1024, and the center electrode 1022 and the metal shell 1024. Is expressed by the product of the rising speed of the voltage V during
  • the capacitances C1 and C2 are determined to be appropriate values at which a current sufficient to generate a strong streamer discharge flows through the spark plug 1010. If it is desired to increase the discharge, the capacitances C1 and C2 are increased. If it is desired to decrease the discharge, the capacitances C1 and C2 are decreased.
  • the case where it is desired to weaken the discharge is, for example, the case where suppression of electrode consumption is desired.
  • the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026 are exposed to the outside of the insulator 1020 and exposed to the combustion chamber 9002. Thereby, a discharge is generated in the combustion chamber 9002, and the mixture can be ignited by the discharge.
  • the embedded portion 1032 of the center electrode 1022 and the embedded portion 1042 of the floating electrode 1026 are embedded in the insulator 1020.
  • the embedded portion 1032 of the center electrode 1022 and the embedded portion 1042 of the floating electrode 1026 are unlikely to become the start point or end point of discharge. For this reason, a discharge is generated exclusively between the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026.
  • the number of exposed portions 1030 of the center electrode 1022 may be increased or decreased.
  • the number of exposed portions 1040 of the floating electrode 1026 may be increased to two or more.
  • a round hole 1060 is formed in the metal shell 1024.
  • a part of the insulator 1020 is conveniently deleted by a broken line.
  • the inside of the round hole 1060 is an accommodation space for accommodating the insulator 1020 and the like.
  • the metal shell 1024 may be replaced with a shape that is difficult to call a “metal metal”.
  • the metal shell 1024 may be replaced with a three-dimensional object such as a plate, a rod, or a rectangular parallelepiped in which the round hole 1060 is formed.
  • the round hole 1060 may be replaced with a hole having another shape.
  • All or part of the outer peripheral surface 1070 of the metal shell 1024 may be covered with an insulator. All or part of the metal shell 1024 may be embedded in the insulator 1020.
  • the insulator 1020 includes a accommodated portion 1080 and a protruding portion 1082.
  • the accommodated portion 1080 is accommodated inside the round hole 1060.
  • the protruding portion 1082 protrudes outside the round hole 1060 and is separated from the metal shell 1024.
  • the protruding portion 1082 protrudes to the axial front end side of the spark plug 1010 and is exposed to the combustion space 9002.
  • the floating electrode 1026 has a structure in which a rod 1802 extends from the tube-shaped portion 1120.
  • the tip end side in the axial direction of the rod body 1802 becomes the exposed portion 1040 of the floating electrode 1026.
  • the rear end side in the axial direction of the rod body 1802 and the tube-shaped portion 1120 serve as the embedded portion 1042 of the floating electrode 1026.
  • the embedded portion 1042 of the floating electrode 1026 includes a tube-shaped portion 1120 and a rod-shaped portion 1122.
  • the tubular portion 1120 is disposed inside the round hole 1060 and is embedded in the accommodated portion 1080.
  • the inner peripheral surface 1180 of the round hole 1060 makes a round around the tube-shaped portion 1120.
  • the inner peripheral surface 1180 of the round hole 1060 and the outer peripheral surface 1170 of the tube-shaped portion 1120 face each other.
  • the floating electrode 1026 and the metal shell 1024 face each other across the insulator 1020 over a wide range.
  • the capacitance C2 between the floating electrode 1026 and the metal shell 1024 increases.
  • a gap between the tubular portion 1120 and the metal shell 1024 is filled with an insulator 1020.
  • the gap is desirably free of voids. However, a slight gap may exist in the gap.
  • the provision of the tube-shaped portion 1120 has an advantage that a range in which the floating electrode 1026 and the metal shell 1024 are opposed to each other is widened, and the capacitance C2 between the floating electrode 1026 and the metal shell 1024 is increased.
  • a structure that forms a large capacitance with the metal shell 1024 may be provided instead of the tube-shaped portion 1120 or in addition to the tube-shaped portion 1120. For example, many rod-shaped parts, coil-shaped parts, plate-shaped parts, etc. may be provided.
  • the tube-shaped part 1120 and the round hole 1060 are arranged coaxially. Thereby, the distance from the outer peripheral surface 1170 of the tube-shaped part 1120 to the inner peripheral surface 1180 of the round hole 1060 becomes uniform, and the bias of the electric field is suppressed.
  • the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026 further protrude from the tip of the protruding portion 1082.
  • An exposed portion 1030 of the center electrode 1022 and an exposed portion 1040 of the floating electrode 1026 protrude to the axial front end side of the spark plug 1010 and are exposed to the combustion space 9002.
  • the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026 are separated from the metal shell 1024. This makes it difficult for discharge to occur between the exposed portion 1030 of the center electrode 1022 and the metal shell 1024, and makes it difficult for discharge to occur between the exposed portion 1040 of the floating electrode 1026 and the metal shell 1024.
  • the exposed portion 1030 of the center electrode 1022 has a rod shape and has a rod tip 1050.
  • the exposed portion 1040 of the floating electrode 1026 also has a rod shape and has a rod tip 1052.
  • the electric field concentrates on the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026, and electric discharge is likely to occur between the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026.
  • the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026 may have other shapes.
  • the exposed portion 1030 of the center electrode 1022 may have a hemispherical shape.
  • the exposed portion 1040 of the floating electrode 1026 may have a tube shape surrounding the exposed portion 1030 of the center electrode 1022.
  • the rod tip 1050 of the exposed portion 1030 of the center electrode 1022 is a plane. However, the rod tip 1050 of the exposed portion 1030 of the center electrode 1022 may not be flat. For example, the rod tip 1050 of the exposed portion 1030 of the center electrode 1022 may be a spherical surface or the like.
  • the exposed portion 1030 of the center electrode 1022 extends in the axial direction of the spark plug 1010.
  • the root side of the exposed portion 1040 of the floating electrode 1026 extends in the axial direction of the spark plug 1010, and the tip side of the exposed portion 1040 of the floating electrode 1026 extends in the radial direction of the spark plug 1010.
  • the rod tip 1052 of the exposed portion 1040 of the floating electrode 1026 faces the radially inner side of the spark plug 1010.
  • the rod tip 1052 of the exposed portion 1040 of the floating electrode 1026 faces in the direction approaching the center electrode 1022, and discharge is likely to occur between the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026.
  • the rod tip 1052 of the exposed portion 1040 of the floating electrode 1026 may face another direction.
  • the rod tip 1052 of the exposed portion 1040 of the floating electrode 1026 may face the tip side of the spark plug 1010 in the axial direction.
  • the root side of the exposed portion 1030 of the center electrode 1022 extends in the axial direction of the spark plug 1010, the distal end side of the exposed portion 1030 of the center electrode 1022 extends in the radial direction of the spark plug 1010, and the exposed portion 1040 of the floating electrode 1026
  • the spark plug 1010 may extend in the axial direction.
  • the rod tip 1050 of the exposed portion 1030 of the center electrode 1022 faces the radially outer side of the spark plug 1010.
  • the insulator 1020 includes a sheath 1090 and a core 1092.
  • An accommodation groove 1100 is formed on the outer peripheral surface of the core 1092.
  • the entire embedded portion 1042 of the floating electrode 1026 is accommodated in the accommodation groove 1100, and the floating electrode 1026 is fixed to the core 1092.
  • the core 1092 to which the floating electrode 1026 is fixed is accommodated in the sheath 1090.
  • the sheath 1090 separates the embedded portion 1042 of the floating electrode 1026 from the metal shell 1024.
  • the insulator 1020 in which the embedded portion 1042 of the floating electrode 1026 is embedded is easily manufactured.
  • the insulator 1020 may be an integrated object.
  • a space for accommodating a part of the embedded portion 1042 of the floating electrode 1026 may be formed in the sheath 1090.
  • the first portion of the embedded portion 1042 of the floating electrode 1026 is accommodated in the accommodating groove formed in the core 1092, and the second portion of the embedded portion 1042 of the floating electrode 1026 is formed in the sheath 1090. It is accommodated in the space.
  • a housing groove, a housing hole, or the like that accommodates the rod-shaped portion 1122 of the embedded portion 1042 of the floating electrode 1026 is formed in the sheath 1090, and the housing groove formed in the core 1092 includes the embedded portion 1042 of the floating electrode 1026. Only the tube-shaped portion 1120 may be accommodated.
  • the insulator 1020 is made of ceramics, resin, or the like.
  • As the ceramic alumina, zirconia or the like is employed.
  • As the resin vinyl chloride resin, fluororesin or the like is employed.
  • the center electrode 1022, the floating electrode 1026, and the metal shell 1024 are made of a conductor.
  • a conductor a metal such as platinum may be employed, an alloy such as stainless steel or nickel alloy may be employed, or conductive ceramics may be employed.
  • the pulse voltage application mechanism 1012 includes a pulse generation circuit 1200 and a cable 1202.
  • the spark plug 1010 further includes a terminal 1028.
  • the terminal 1028 and the positive electrode 1210 of the pulse generation circuit 1200 are electrically connected by a cable 1202.
  • the metal shell 1024 and the negative electrode 1212 of the pulse generation circuit 1200 are grounded.
  • the pulse generation circuit 1200 When the pulse generation circuit 1200 generates a pulse voltage between the positive electrode 1210 and the negative electrode 1212, a pulse voltage is applied between the terminal 1028 and the metal shell 1024, and between the center electrode 1022 and the metal shell 1024. A pulse voltage is applied.
  • the terminal 1028 may be omitted, and the cable 1202 may be directly attached to the center electrode 1022.
  • the cable 1202 may be omitted, and the positive electrode 1210 of the pulse generation circuit 1200 may be directly attached to the terminal 1028.
  • the type of the pulse generation circuit 1200 is preferably an inductive energy storage type. However, the form of the pulse generation circuit 1200 may be other than the induction energy storage type.
  • Pulse voltage waveform The waveform of the pulse voltage is determined so that streamer discharge occurs but arc discharge does not occur.
  • the peak voltage is 5 to 40 kV
  • the half width is 50 to 5000 ns
  • the repetition frequency is 5 to 500 kpps. That the discharge is a streamer discharge is identified by the waveform of the current flowing through the spark plug 1010. This is because the current flowing through the spark plug 1010 increases abruptly when the discharge reaches an arc discharge.
  • a burst signal that repeatedly applies a single pulse during the burst period may be applied between the center electrode 1022 and the metal shell 1024.
  • the burst period is approximately 0.1 to 5 ms.
  • the pulse voltage is a unipolar positive pulse, with the center electrode 1022 serving as the anode and the metal shell 1024 serving as the cathode.
  • the pulse voltage is a unipolar negative pulse, the center electrode 1022 can be a cathode, and the metal shell 1024 can be an anode.
  • the pulse voltage may be bipolar.
  • the insulator 1020 includes a protruding portion 1084 in addition to the accommodated portion 1080 and the protruding portion 1082.
  • the protruding portion 1084 protrudes outside the round hole 1060 and is separated from the metal shell 1024.
  • the protruding portion 1084 protrudes toward the rear end side in the axial direction of the spark plug 1010 and is exposed to the outside of the combustion container 9000.
  • a shaft hole 1220 is formed in the insulator 1020.
  • a part of the center electrode 1022 is conveniently removed by a broken line so that the shaft hole 1220 can be easily distinguished from other components.
  • the shaft hole 1220 extends from the protruding portion 1082 to the protruding portion 1084 via the accommodated portion 1080.
  • the center electrode 1022 has a rod shape.
  • the center electrode 1022 includes an exposed portion 1034 in addition to the exposed portion 1030 and the embedded portion 1032.
  • the exposed portion 1034 of the center electrode 1022 protrudes outside the shaft hole 1220.
  • the exposed portion 1034 of the center electrode 1022 protrudes toward the rear end side in the axial direction of the spark plug 1010.
  • a terminal 1028 is screwed into the exposed portion 1034 of the center electrode 1022. Thereby, the terminal 1028 is separated from the metal shell 1024, and power feeding to the center electrode 1022 is facilitated.
  • Center electrode 1022 is fixed to insulator 1020 by screwing terminal 1028.
  • the spark plug 1010 further includes gasket washers 1230 and 1232.
  • the gasket washers 1230 and 1232 are sandwiched between the insulator 1020 and the metal shell 1024 inside the round hole 1060. Thereby, the air-fuel mixture is less likely to leak from the gap between the insulator 1020 and the metal shell 1024.
  • a spark plug 1010 and a combustion container 9000 are prepared, and the spark plug 1010 is attached to the combustion container 9000.
  • the combustion container 9000 may be omitted, and the spark plug 1010 may be used to ignite the air-fuel mixture filled in the opened combustion space.
  • a pulse voltage is applied between the terminal 1028 and the metal shell 1024, and a pulse voltage is applied between the center electrode 1022 and the metal shell 1024.
  • a strong streamer discharge is generated between the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026, and the air-fuel mixture is ignited.
  • the ignition device 1000 is mainly used for igniting an air-fuel mixture filled in a combustion chamber of an engine.
  • the engine is preferably an internal combustion engine, and more preferably a reciprocating engine.
  • the reciprocating engine may be either a 4-cycle engine or a 2-cycle engine.
  • the engine may be an external combustion engine.
  • the engine may be an internal combustion engine other than a reciprocating engine.
  • the engine may be a rotary engine.
  • the engine may be a gas engine.
  • the engine is typically built into a car.
  • the engine may be incorporated in a transport machine other than an automobile.
  • the engine may be incorporated in a railway vehicle, an industrial vehicle, a ship, an aircraft, a spacecraft, or the like.
  • the engine may be incorporated in a machine other than the transport machine.
  • the engine may be incorporated in a tool, a farm tool, an engine generator, or the like.
  • the air-fuel mixture is a mixture of air and fuel oil.
  • the air-fuel mixture may be a mixture of air and combustible gas.
  • the air-fuel mixture may be a mixture of air and hydrogen gas, propane gas, butane gas, or the like.
  • the combustible gas may be a mixture.
  • Air may be replaced with other types of flammable gases.
  • air may be replaced with oxygen.
  • the fuel oil may be replaced with other types of flammable liquids.
  • the fuel oil may be replaced with methanol.
  • the pressure of the air-fuel mixture is typically atmospheric pressure, but may be reduced or increased.
  • the second embodiment relates to a spark plug that replaces the spark plug of the first embodiment.
  • important common points and differences between the spark plug of the first embodiment and the spark plug of the second embodiment will be described.
  • the components of the spark plug of the second embodiment are given the same names as the corresponding components of the spark plug of the first embodiment.
  • FIG. 10 is a perspective view of a spark plug according to the second embodiment.
  • the schematic diagram of FIG. 11 is sectional drawing of the ignition plug of 2nd Embodiment.
  • the schematic diagram of FIG. 12 is an exploded perspective view of the insulator of the second embodiment.
  • the schematic diagram of FIG. 13 is a perspective view of the floating electrode of the second embodiment.
  • the spark plug 2010 includes an insulator 2020, a center electrode 2022, a metal shell 2024, and a floating electrode 2026, as in the first embodiment.
  • the center electrode 2022 includes an exposed portion 2030 and an embedded portion 2032.
  • the floating electrode 2026 includes an exposed portion 2040 and an embedded portion 2042.
  • the exposed portion 2040 of the floating electrode 2026 is relatively close to the exposed portion 2030 of the center electrode 2022, and the metal shell 2024 is relatively far from the exposed portion 2030 of the center electrode 2022.
  • the electrostatic capacitance C1 between the center electrode 2022 and the floating electrode 2026 is relatively small, and the electrostatic capacitance C2 between the floating electrode 2026 and the metal shell 2024 is relatively large. Therefore, when a pulse voltage is applied between the center electrode 2022 and the metal shell 2024, a high voltage is induced between the center electrode 2022 and the floating electrode 2026, and the exposed portion 2030 of the center electrode 2022 and the floating electrode 2026 A powerful streamer discharge is generated between the exposed portion 2040 and the exposed portion 2040.
  • This powerful streamer discharge ignites the air-fuel mixture. It is the same as in the first embodiment that the air-fuel mixture can be ignited stably even when the discharge volume is large and the combustion is difficult. It is the same as in the first embodiment that the current flowing through the spark plug 2010 decreases and the energy consumption per unit discharge volume decreases.
  • a shaft hole 2220 is formed in the insulator 2020.
  • the shaft hole 2220 becomes a hollow space inside the insulator 2020.
  • the embedded portion 2032 of the center electrode 2022 is accommodated in the shaft hole 2220.
  • the embedded portion 2032 of the center electrode 2022 includes a hollow holding portion 2260.
  • the hollow holding portion 2260 is held hollow inside the shaft hole 2220.
  • a gap 2250 is formed between the hollow holding portion 2260 and the insulator 2020.
  • the center electrode 2022 is surrounded by the gap 2250 inside the insulator 2020, and the capacitance C1 between the center electrode 2022 and the floating electrode 2026 is reduced.
  • the hollow holding part 2260 occupies the main part of the buried part 2032 of the center electrode 2022.
  • the ratio of the hollow holding portion 2260 occupying the buried portion 2032 of the center electrode 2022 may be increased or decreased.
  • the embedded portion 2042 of the floating electrode 2026 includes a tube-shaped portion 2120.
  • the embedded portion 2032 of the center electrode 2022 passes through the inside of the tube-shaped portion 2120.
  • the portion of the embedded portion 2032 of the center electrode 2022 that mainly contributes to the increase in the capacitance C1 between the center electrode 2022 and the floating electrode 2026 is a portion that passes through the tube of the tube-shaped portion 2120. For this reason, even if the ratio of the hollow holding portion 2260 occupying the buried portion 2032 of the center electrode 2022 is reduced, the portion of the tube-shaped portion 2120 that passes through the tube is made the hollow holding portion 2260.
  • the shaft hole 2220 may be replaced with a hollow space having a shape difficult to call a “shaft hole”.
  • the insulator 2020 includes a sheath 2090 and a core 2092.
  • the cross-sectional shape of the axial hole 2220 is substantially the same as the cross-sectional shape of the embedded portion 2032 of the center electrode 2022 on the rear end side in the axial direction of the core 2092 and the sheath 2090, and on the front end side in the axial direction of the core 2092. It is larger than the cross-sectional shape of the embedded portion 2032.
  • the insulator 2020 includes a sheath 2090 and a core 2092.
  • a housing hole 2260 is formed in the sheath 2090.
  • the core 2092 includes a holding shaft 2270.
  • the floating electrode 2026 has a structure in which a rod body 2802 extends from the tubular portion 2120.
  • the embedded portion 2042 of the floating electrode 2026 includes a tube-shaped portion 2120 and a rod-shaped portion 2122.
  • a holding shaft 2270 is inserted into the tube-shaped portion 2120, and the floating electrode 2026 is fixed to the core 2092.
  • the core 2092 to which the floating electrode 2026 is fixed is accommodated in the sheath 2090.
  • the bar-shaped portion 2122 is accommodated in the accommodation hole 2260.
  • the embedded portion 2042 of the floating electrode 2066 is embedded in the insulator 2020.
  • the floating electrode 2026 includes two exposed portions 2040 unlike the first embodiment. This increases the discharge volume.
  • the number of exposed portions 2040 of the floating electrode 2026 may be increased or decreased.
  • the exposed portion 2040 of the floating electrode 2026 is disposed rotationally symmetrically around the exposed portion 2032 of the center electrode 2022. As a result, the discharge is uniformly generated and the discharge volume is increased.
  • the exposed portion 2030 of the center electrode 2022 has a rod tip 2050.
  • the number of rod tips 2050 is one, and the rod tips 2050 are flat.
  • the center electrode 2022 is fixed to the insulator 2020 by screwing the terminal 2028.
  • the third embodiment relates to a spark plug that replaces the spark plug of the first embodiment.
  • important common points and differences between the spark plug of the first embodiment and the spark plug of the third embodiment will be described.
  • the structure of the spark plug of 1st Embodiment or another embodiment is employ
  • the components of the spark plug of the third embodiment are given the same names as the corresponding components of the spark plug of the first embodiment.
  • FIG. 14 is a perspective view of the spark plug of the third embodiment.
  • the schematic diagram of FIG. 15 is sectional drawing of the ignition plug of 3rd Embodiment.
  • the spark plug 3010 includes an insulator 3020, a center electrode 3022, a metal shell 3024, and a floating electrode 3026, as in the first embodiment.
  • the center electrode 3022 includes an exposed portion 3030 and an embedded portion 3032.
  • the floating electrode 3026 includes an exposed portion 3040 and an embedded portion 3042.
  • the exposed portion 3040 of the floating electrode 3026 is relatively close to the exposed portion 3030 of the center electrode 3022, and the metal shell 3024 is relatively far from the exposed portion 3030 of the center electrode 3022.
  • the capacitance C1 between the center electrode 3022 and the floating electrode 3026 is relatively small, and the capacitance C2 between the floating electrode 3026 and the metal shell 3024 is relatively large. Therefore, when a pulse voltage is applied between the center electrode 3022 and the metal shell 3024, a high voltage is induced between the center electrode 3022 and the floating electrode 3026, and the exposed portion 3030 of the center electrode 3022 and the floating electrode 3026 A powerful streamer discharge is generated between the exposed portion 3040 and the exposed portion 3040.
  • This powerful streamer discharge ignites the air-fuel mixture. It is the same as in the first embodiment that the air-fuel mixture can be ignited stably even when the discharge volume is large and the combustion is difficult. It is the same as in the first embodiment that the current flowing through the spark plug 3010 decreases and the energy consumption per unit discharge volume decreases.
  • the spark plug 3010 includes four floating electrodes 3026.
  • the number of floating electrodes 3026 may be increased or decreased. More generally, two or more floating electrodes 3026 are provided.
  • the four floating electrodes 3026 are insulated from each other. Thereby, the potentials of the four floating electrodes 3026 are independent. For this reason, even if discharge occurs between the exposed portion 3030 of the center electrode 3022 and the exposed portion 3040 of one floating electrode 3026, the exposed portion 3030 of the central electrode 3022 and the exposed portion 3040 of the other floating electrode 3026 Discharge is not hindered, multi-point discharge is likely to occur, and the discharge volume increases. Since each discharge constituting the multipoint discharge is a powerful streamer discharge, it has the ability to ignite the air-fuel mixture by itself. In multi-point discharge, two or more discharges occur simultaneously at different locations. However, the timing of two or more discharges may be slightly shifted.
  • FIG. 16 shows the positional relationship of the electrode of 3rd Embodiment.
  • the exposed portion 3040 of the floating electrode 3026 is relatively close to the exposed portion 3030 of the center electrode 3022, and the metal shell 3024 is relatively away from the exposed portion 3030 of the center electrode 3022. Therefore, the discharge path length L1 from the exposed portion 3040 of the floating electrode 3026 to the exposed portion 3030 of the center electrode 3022 via the combustion chamber 9002 is relatively short, and the center electrode 3022 passes from the metal shell 3024 via the combustion chamber 9002.
  • the discharge path length L2 to the exposed portion 3030 is relatively long, and L1 ⁇ L2 is established.
  • the discharge gap between the exposed portion 3030 of the center electrode 3022 and the exposed portion 3040 of the floating electrode 3026 is narrower than the discharge gap between the exposed portion 3030 of the center electrode 3022 and the metal shell 3024.
  • the discharge path length L1 is uniform for each of the four floating electrodes 3026. As a result, the discharge is not biased between the exposed portion 3030 of the center electrode 3022 and the exposed portion 3040 of the specific floating electrode 3026, and multipoint discharge is likely to occur. However, there may be slight variations in the discharge path length L1.
  • FIG. 17 shows an equivalent circuit of the spark plug of the third embodiment.
  • the discharge is not biased between the exposed portion 3030 of the center electrode 3022 and the exposed portion 3040 of the specific floating electrode 3026, and multipoint discharge is likely to occur.
  • the electrostatic capacitance C1 may have slight variations, and the electrostatic capacitance C2 may have slight variations.
  • the insulator 3020 is an integral object unlike the first embodiment. Thereby, the mechanical strength of the insulator 3020 is improved and leakage of the air-fuel mixture is suppressed.
  • the insulator 3020 includes a accommodated portion 3080 and a protruding portion 3082 as in the first embodiment.
  • a round hole 3060 is formed in the metal shell 3024.
  • the accommodated portion 3080 is accommodated inside the round hole 3060.
  • the protruding portion 3082 protrudes outside the round hole 3060.
  • the protruding portion 3082 protrudes toward the tip end side in the axial direction of the spark plug 3010 and is exposed to the combustion space 9002.
  • a central groove 3300 and four radial grooves 3302 are formed on the distal end surface 3290 of the protrusion 3082.
  • the central groove 3300 is relatively deep and the four radial grooves 3302 are relatively shallow.
  • Four radial grooves 3302 extend radially from the central groove 3300.
  • the exposed portion 3030 of the center electrode 3022 is accommodated in the center groove 3300.
  • One exposed portion 3040 of the floating electrode 3026 is accommodated in each of the four radial grooves 3302. As a result, the exposed portion 3040 of the adjacent floating electrode 3026 is separated by the insulator 3020, and the discharge is less likely to occur between the exposed portions 3040 of the adjacent floating electrode 3026.
  • the exposed portion 3030 of the center electrode 3022 and the exposed portion 3040 of the floating electrode 3026 are not separated by the insulator 3020, and a discharge is easily generated between the exposed portion 3030 of the center electrode 3022 and the exposed portion 3040 of the floating electrode 3026. Become.
  • a hole 3310 is formed at the bottom of the four radial grooves 3302.
  • a part of the floating electrode 3026 is conveniently deleted by a broken line in order to make the hole 3310 easily distinguishable from other components.
  • the hole 3310 extends in the axial direction of the spark plug 3010.
  • a conductor film is formed on the inner peripheral surface of the hole 3310 and the bottom of the radial groove 3302 by plating. The conductor film becomes the floating electrode 3026.
  • a conductive paste may be baked on the inner peripheral surface of the hole 3310 and the bottom of the radial groove 3302.
  • the holes 3310 and the radial grooves 3302 may be filled with a conductor. Thereby, the floating electrode 3026 in which the embedded portion 3042 is embedded in the integrated insulator 3020 is easily manufactured.
  • the hollow holding portion 3260 of the buried portion 3032 of the center electrode 3022 is hollowly held inside a shaft hole 3220 formed in the insulator 3020 as in the second embodiment.
  • the center electrode 3022 is surrounded by the gap 3250 inside the insulator 3020, and the capacitance C1 between the center electrode 3022 and the floating electrode 3026 is reduced.
  • the fourth embodiment relates to a spark plug that replaces the spark plug of the first embodiment.
  • important common points and differences between the spark plug of the first embodiment and the spark plug of the fourth embodiment will be described.
  • the components of the spark plug of the fourth embodiment are given the same names as the corresponding components of the spark plug of the first embodiment.
  • FIG. 18 is a perspective view of the spark plug of the fourth embodiment.
  • the schematic diagram of FIG. 19 is sectional drawing of the ignition plug of 4th Embodiment.
  • the schematic diagram of FIG. 20 is an exploded perspective view of the insulator of the fourth embodiment.
  • the schematic diagram of FIG. 21 is a perspective view of the floating electrode of 4th Embodiment.
  • the spark plug 4010 includes an insulator 4020, a center electrode 4022, a metal shell 4024, and a floating electrode 4026, as in the first embodiment.
  • the center electrode 4022 includes an exposed portion 4030 and an embedded portion 4032.
  • the floating electrode 4026 includes an exposed portion 4040 and an embedded portion 4042.
  • the exposed portion 4040 of the floating electrode 4026 is relatively close to the exposed portion 4030 of the center electrode 4022, and the metal shell 4024 is relatively far from the exposed portion 4030 of the center electrode 4022.
  • the capacitance C1 between the center electrode 4022 and the floating electrode 4026 is relatively small, and the capacitance C2 between the floating electrode 4026 and the metal shell 4024 is relatively large. Therefore, when a pulse voltage is applied between the center electrode 4022 and the metal shell 4024, a high voltage is induced between the center electrode 4022 and the floating electrode 4026, and the exposed portion 4030 of the center electrode 4022 and the floating electrode 4026 A powerful streamer discharge is generated between the exposed portion 4040 and the exposed portion 4040.
  • This powerful streamer discharge ignites the air-fuel mixture. It is the same as in the first embodiment that the air-fuel mixture can be ignited stably even when the discharge volume is large and the combustion is difficult. It is the same as in the first embodiment that the current flowing through the spark plug 4010 decreases and the energy consumption per unit discharge volume decreases.
  • the insulator 4020 includes a sheath 4090 and a core 4092.
  • An accommodation groove 4272 is formed on the inner peripheral surface of the sheath 4090.
  • the core 4092 includes a holding shaft 4270.
  • the embedded portion 4042 of the floating electrode 4026 includes a tube-shaped portion 4120 and a rod-shaped portion 4122.
  • a holding shaft 4270 is inserted into the tube-shaped portion 4120, and the floating electrode 4026 is fixed to the core 4092.
  • the core 4092 to which the floating electrode 4026 is fixed is accommodated in the sheath 4090. At this time, the bar-shaped portion 4122 is received in the receiving groove 4272.
  • the embedded portion 4042 of the floating electrode 4066 is embedded in the insulator 4020.
  • an O-ring 4320 is sandwiched between the sheath 4090 and the core 4092. This makes it difficult for the air-fuel mixture to leak from the gap between the sheath 4090 and the core 4092.
  • the floating electrode 4026 includes two exposed portions 4040. This increases the discharge volume. The number of exposed portions 4040 of the floating electrode 4026 may be increased or decreased.
  • the fifth embodiment relates to a spark plug that replaces the spark plug of the first embodiment.
  • important common points and differences between the spark plug of the first embodiment and the spark plug of the fifth embodiment will be described.
  • the structure of the spark plug of 1st Embodiment or another embodiment is employ
  • the components of the spark plug of the fifth embodiment are given the same names as the corresponding components of the spark plug of the first embodiment.
  • FIG. 22 is a perspective view of the spark plug of the fifth embodiment.
  • the schematic diagram of FIG. 23 is sectional drawing of the ignition plug of 5th Embodiment.
  • the schematic diagram of FIG. 24 is an exploded perspective view of the insulator of 5th Embodiment.
  • the schematic diagram of FIG. 25 is a perspective view of the floating electrode of the fifth embodiment.
  • the spark plug 5010 includes an insulator 5020, a center electrode 5022, a metal shell 5024, and a floating electrode 5026, as in the first embodiment.
  • the metal shell 5024 includes an exposed portion 5330.
  • the center electrode 5022 includes an embedded portion 5032.
  • the floating electrode 5026 includes an exposed portion 5040 and an embedded portion 5042.
  • the buried portion 5032 of the center electrode 5022 is provided to insulate the high-voltage center electrode 5022.
  • the buried portion 5042 of the floating electrode 5026 is provided to increase the capacitance C1 between the center electrode 5022 and the floating electrode 5026.
  • the exposed portion 5040 of the floating electrode 5026 is relatively close to the exposed portion 5330 of the metal shell 5024, and the center electrode 5022 is relatively far from the exposed portion 5330 of the metal shell 5024. Contrary to the first embodiment, the capacitance C1 between the center electrode 5022 and the floating electrode 5026 is relatively large, and the capacitance C2 between the floating electrode 5026 and the metal shell 5024 is relatively small. . Therefore, when a pulse voltage is applied between the center electrode 5022 and the metal shell 5024, unlike the first embodiment, a high voltage is induced between the floating electrode 5026 and the metal shell 5024, and the floating electrode 5026 A powerful streamer discharge is generated between the exposed portion 5040 and the exposed portion 5330 of the metal shell 5024.
  • This powerful streamer discharge ignites the air-fuel mixture. It is the same as in the first embodiment that the air-fuel mixture can be ignited stably even when the discharge volume is large and the combustion is difficult. It is the same as in the first embodiment that the current flowing through the spark plug 5010 decreases and the energy consumption per unit discharge volume decreases.
  • FIG. 26 shows the positional relationship of the electrodes of the fifth embodiment.
  • the exposed portion 5040 of the floating electrode 5026 is relatively close to the exposed portion 5330 of the metal shell 5024, and the center electrode 5022 is relatively far from the exposed portion 5330 of the metal shell 5024. Therefore, the discharge path length L1 from the exposed portion 5040 of the floating electrode 5026 to the exposed portion 5330 of the metal shell 5024 via the combustion chamber 9002 is relatively short, and the metal shell 5024 from the center electrode 5022 via the combustion chamber 9002 is relatively short.
  • the discharge path length L2 to the exposed portion 5330 is relatively long, and L1 ⁇ L2 is established.
  • the discharge gap between the exposed portion 5040 of the floating electrode 5026 and the exposed portion 5330 of the metal shell 5024 is narrower than the discharge gap between the center electrode 5022 and the exposed portion 5330 of the metal shell 5024. For this reason, a discharge is relatively unlikely to occur between the center electrode 5022 and the exposed portion 5040 of the floating electrode 5026. In addition, a discharge is relatively easily generated between the exposed portion 5040 of the floating electrode 5026 and the exposed portion 5330 of the metal shell 5024.
  • the electrostatic capacitance C1 is at least larger than the electrostatic capacitance C2, and preferably 10 times or more of the electrostatic capacitance C2.
  • the exposed portion 5330 of the metal shell 5024 and the exposed portion 5040 of the floating electrode 5026 are exposed to the outside of the insulator 5020 and exposed to the combustion chamber 9002. As a result, a discharge is generated in the combustion chamber 9002, and the mixture can be ignited by the discharge.
  • the embedded portion 5032 of the center electrode 5022 and the embedded portion 5042 of the floating electrode 5026 are embedded in the insulator 5020. Unlike the first embodiment, the center electrode 5022 is not exposed to the axial front end side of the spark plug 5010 and is not exposed to the combustion chamber 9002.
  • the center electrode 5022 and the exposed portion 5330 of the metal shell 5024 are separated by the insulator 5020, and it is difficult for electric discharge to occur between the center electrode 5022 and the exposed portion 5330 of the metal shell 5024.
  • the center electrode 5022 and the exposed portion 5040 of the floating electrode 5026 are separated by the insulator 5020, so that it is difficult for discharge to occur between the center electrode 5022 and the exposed portion 5040 of the floating electrode 5026.
  • the center electrode 5022 may have an exposed portion as in the first embodiment.
  • a round hole 5060 is formed in the metal shell 5024 as in the first embodiment.
  • the inside of the round hole 5060 becomes an accommodation space for accommodating the insulator 5020 and the like.
  • the metal shell 5024 may be replaced with a formation that is difficult to call “metal metal”.
  • the round hole 5060 may be replaced with a hole having another shape.
  • a part of the outer peripheral surface 5072 of the metal shell 5024 may be covered with an insulator.
  • a part of the metal shell 5024 may be embedded in the insulator 5020.
  • the embedded portion 5042 of the floating electrode 5026 includes a tube-shaped portion 5120.
  • the inside of the tube-shaped portion 5120 is an internal space filled with the insulator 5020 and the like.
  • the insulator 5020 includes a filled portion 5700 that is filled in the tube of the tube-shaped portion 5120.
  • the embedded portion 5032 of the center electrode 5022 includes a rod-shaped portion 5702.
  • the rod-shaped portion 5702 is disposed in the tube of the tube-shaped portion 5120 and is embedded in the filled portion 5700.
  • the tube-shaped portion 5120 makes a round around the rod-shaped portion 5702. Thereby, the center electrode 5022 and the floating electrode 5026 face each other across the insulator 5020 over a wide range.
  • a gap between the tube-shaped portion 5120 and the rod-shaped portion 5702 is filled with an insulator 5020. There are no voids in the gap. For this reason, the electrostatic capacitance C2 between the center electrode 5022 and the floating electrode 5026 increases. However, a slight gap may exist in the gap.
  • the provision of the tube-shaped portion 5120 has an advantage that a range where the center electrode 5022 and the floating electrode 5026 are opposed to each other is widened, and an electrostatic capacitance C1 between the center electrode 5022 and the floating electrode 5026 is increased.
  • a structure that forms a large capacitance between the embedded portion 5032 of the center electrode 5022 may be provided.
  • many rod-shaped parts, coil-shaped parts, plate-shaped parts, etc. may be provided.
  • a structure that forms a large capacitance between the floating electrode 5026 and the structure may be provided.
  • a tube-shaped part or the like may be provided.
  • the tube-shaped portion 5120 and the rod-shaped portion 5702 are arranged coaxially. Thereby, the distance from the outer peripheral surface of the rod-shaped part 5702 to the inner peripheral surface of the tube-shaped part 5120 becomes uniform, and the bias of the electric field is suppressed.
  • the insulator 5020 includes a accommodated portion 5080.
  • the accommodated portion 5080 is accommodated inside the round hole 5060.
  • the accommodated part 5080 includes a hollow retained part 5340.
  • the hollow holding portion 5340 is hollowly held inside the round hole 5060.
  • the insulator 5020 is surrounded by the gap inside the round hole 5060, and the capacitance C2 between the floating electrode 5026 and the metal shell 5024 is reduced.
  • the exposed portion 5040 of the floating electrode 5026 protrudes outside the accommodated portion 5080, protrudes outside the round hole 5060, and is separated from the center electrode 5022. This makes it difficult for discharge to occur between the center electrode 5022 and the exposed portion 5040 of the floating electrode 5026.
  • the exposed portion 5040 of the floating electrode 5026 has a rod shape and has a rod tip 5052.
  • the electric field concentrates on the exposed portion 5040 of the floating electrode 5026, and electric discharge easily occurs between the exposed portion 5040 of the floating electrode 5026 and the exposed portion 5330 of the metal shell 5024.
  • the exposed portion 5040 of the floating electrode 5026 may have other shapes.
  • the rod tip 5052 of the exposed portion 5040 of the floating electrode 5026 faces the radially outer side of the spark plug 5010.
  • the rod tip 5052 of the exposed portion 5040 of the floating electrode 5026 faces in the direction approaching the metal shell 5024, and electric discharge is likely to occur between the exposed portion 5040 of the floating electrode 5026 and the exposed portion 5330 of the metal shell 5024.
  • the rod tip 5052 of the exposed portion 5040 of the floating electrode 5026 may face another direction.
  • the rod tip 5052 of the exposed portion 5040 of the floating electrode 5026 may face the tip side in the axial direction of the spark plug 5010.
  • the insulator 5020 includes a sheath 5090 and a core 5092.
  • a housing groove 5272 is formed on the inner peripheral surface of the sheath 5090.
  • the core 5092 includes a holding shaft 5270.
  • the embedded portion 5042 of the floating electrode 5026 includes a tube-shaped portion 5120 and a rod-shaped portion 5122.
  • a holding shaft 5270 is inserted into the tube-shaped portion 5120, and the floating electrode 5026 is fixed to the core 5092.
  • the core 5092 to which the floating electrode 5026 is fixed is accommodated in the sheath 5090. At this time, the bar-shaped portion 5122 is received in the receiving groove 5272.
  • the embedded portion 5042 of the floating electrode 5026 is embedded in the insulator 5020.
  • An O-ring 5320 is sandwiched in the gap between the sheath 5090 and the core 5092. This makes it difficult for the air-fuel mixture to leak from the gap between the sheath 5090 and the core 5092.
  • floating electrode instead of the floating electrode 5026, as shown in FIG. 27, two or more floating electrodes 5026a insulated from each other may be provided. Accordingly, the potentials of two or more floating electrodes 5026a are independent, and even if a discharge occurs between one floating electrode 5026a and the metal shell 5024, the discharge between the other floating electrode 5026a and the metal shell 5024 occurs. Is not hindered, and multipoint discharge is likely to occur.
  • the sixth embodiment relates to a spark plug that replaces the spark plug of the first embodiment.
  • the sixth embodiment relates to a spark plug that replaces the spark plug of the first embodiment.
  • important common points and differences between the spark plug of the first embodiment and the spark plug of the sixth embodiment will be described.
  • the components of the spark plug of the sixth embodiment are given the same names as the corresponding components of the spark plug of the first embodiment.
  • FIG. 28 is a perspective view of the spark plug of the sixth embodiment.
  • the circuit diagram of FIG. 29 shows an equivalent circuit of the spark plug of the sixth embodiment.
  • the spark plug 6010 includes an insulator 6020, a center electrode 6022, a metal shell 6024, a floating electrode 6026, and a capacitor 6350.
  • the center electrode 6022 includes an exposed portion 6030 and an embedded portion 6032.
  • the floating electrode 6026 includes an exposed portion 6040.
  • One terminal of the capacitor 6350 is electrically connected to the floating electrode 6026.
  • the other terminal of the capacitor 6350 is electrically connected to the metal shell 6024.
  • Capacitor 6350 is externally attached to insulator 6020.
  • the embedded portion 6032 of the center electrode 6022 is provided to insulate the high-voltage center electrode 6022.
  • the exposed portion 6030 of the center electrode 6022 and the exposed portion 6040 of the floating electrode 6026 are exposed to the outside of the insulator 6020.
  • the embedded portion 6032 of the center electrode 6022 is embedded in the insulator 6020.
  • the floating electrode 6026 may include a buried portion.
  • the exposed portion 6040 of the floating electrode 6026 is relatively close to the exposed portion 6030 of the center electrode 6022, and the metal shell 6024 is relatively far from the exposed portion 6030 of the center electrode 6022.
  • the capacitance C1 between the center electrode 6022 and the floating electrode 6026 and the capacitance C2 between the floating electrode 6026 and the metal shell 6024 are the capacitance relationship C1 ⁇ C2 mentioned in the description of the first embodiment. Does not necessarily satisfy. However, the capacitance C1 is relatively small, and the sum C2 + C3 of the capacitance C2 and the capacitance C3 of the capacitor 6350 is relatively large, and C1 ⁇ C2 + C3 is established.
  • a floating electrode 6026a having a crown shape as shown in FIG. 30 may be used.
  • two or more floating electrodes 6026b having a rod shape and insulated from each other may be used.
  • two or more floating electrodes 6026c having a film shape and insulated from each other may be used.
  • FIG. 33 is a graph showing changes in the form of discharge due to pressure and voltage. From FIG. 33, it is understood that discharge is more likely to occur when a capacitor is externally attached than when a capacitor is not externally attached. On the other hand, the voltage at which arc discharge occurs is not affected by the presence or absence of a capacitor. Therefore, when a capacitor is externally attached, the range in which streamer discharge occurs is widened.

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  • Spark Plugs (AREA)

Abstract

This spark plug is provided with: an insulator; a center electrode; a main metal fitting; and a floating electrode. An exposed area of the floating electrode is relatively close to an exposed area of the center electrode, and the main metal fitting is relatively far away from the exposed area of the center electrode. A capacitance formed between the floating electrode and the center electrode is relatively small. A capacitance formed between the floating electrode and the main metal fitting is relatively large. Alternatively, the exposed area of the floating electrode is relatively close to the exposed area of the main metal fitting, and the center electrode is relatively far away from the exposed area of the main metal fitting. The capacitance formed between the floating electrode and the center electrode is relatively large. The capacitance formed between the floating electrode and the main metal fitting is relatively small. A capacitor is externally attached to the insulator when so required due to the capacitance of the main body of the spark plug.

Description

点火プラグ、点火装置及び混合気に点火する方法Spark plug, ignition device, and method of igniting an air-fuel mixture

　本発明は、点火プラグ、点火装置及び混合気に点火する方法に関する。 The present invention relates to a spark plug, an ignition device, and a method for igniting an air-fuel mixture.

　一般的な点火プラグは、高圧電極と接地電極とを備える。高圧電極と接地電極との間には高圧が印加され、高圧電極と接地電極との間隙にはアーク放電が発生させられる。 A typical spark plug includes a high-voltage electrode and a ground electrode. A high voltage is applied between the high voltage electrode and the ground electrode, and an arc discharge is generated in the gap between the high voltage electrode and the ground electrode.

　特許文献１の点火プラグにおいては、高圧電極（中心電極３）及び接地電極（外側電極６及び接地電極８）に加えて浮遊電極（浮遊電極１１）が設けられる。高圧電極と接地電極との間には高圧が印加され、高圧電極と浮遊電極との間隙には放電が発生させられる。 In the spark plug of Patent Document 1, a floating electrode (floating electrode 11) is provided in addition to a high-voltage electrode (center electrode 3) and a ground electrode (outer electrode 6 and ground electrode 8). A high voltage is applied between the high voltage electrode and the ground electrode, and a discharge is generated in the gap between the high voltage electrode and the floating electrode.

　特許文献１には、浮遊電極を高圧電極に近づけることが記載されている（段落００１５）。また、特許文献１には、高圧電極と浮遊電極との間の静電容量を１０ｐＦ以上とし、浮遊電極と接地電極との間の静電容量を３ｐＦ以上とすることが記載されている。特許文献１においては、前者の静電容量と後者の静電容量との大小関係は不明である。 Patent Document 1 describes that a floating electrode is brought close to a high voltage electrode (paragraph 0015). Patent Document 1 describes that the capacitance between the high-voltage electrode and the floating electrode is 10 pF or more, and the capacitance between the floating electrode and the ground electrode is 3 pF or more. In Patent Document 1, the magnitude relationship between the former capacitance and the latter capacitance is unknown.

特開平５－３６４６３号公報Japanese Patent Laid-Open No. 5-36463

　一般的な点火プラグにおいては、消費エネルギーが多いにもかかわらず、放電が広範囲に広がらず、放電体積が小さいという問題がある。希薄燃焼が行われる場合等の難燃焼条件においては、放電体積が小さいことは点火の安定性を損なう。この問題は、特許文献１のような改良された点火プラグによっても十分に改善されない。 In general spark plugs, there is a problem that the discharge does not spread over a wide range and the discharge volume is small despite a large amount of energy consumption. Under difficult combustion conditions such as when lean combustion is performed, the small discharge volume impairs ignition stability. This problem is not sufficiently improved even by the improved spark plug as disclosed in Patent Document 1.

　本発明は、この問題を解決するためになされる。本発明の目的は、難燃焼条件であっても混合気に安定して点火でき消費エネルギーが減少する点火プラグ、点火装置及び混合気に点火する方法を提供することである。 The present invention is made to solve this problem. An object of the present invention is to provide an ignition plug, an ignition device, and a method for igniting an air-fuel mixture that can stably ignite the air-fuel mixture even under difficult combustion conditions and reduce energy consumption.

　本発明の第１から第７までの局面は、点火プラグに向けられる。 The first to seventh aspects of the present invention are directed to the spark plug.

　本発明の第１の局面においては、碍子、高圧電極、接地電極及び浮遊電極が設けられる。高圧電極は、第１の露出部及び第１の被埋設部を備える。浮遊電極は、第２の露出部及び第２の被埋設部を備える。第１の露出部及び第２の露出部は、碍子の外部に露出する。第１の被埋設部及び第２の被埋設部は、碍子に埋設される。第２の露出部は、第１の露出部に相対的に近く、接地電極は第１の露出部から相対的に遠い。高圧電極と浮遊電極との間の静電容量は相対的に小さい。浮遊電極と接地電極との間の静電容量は相対的に大きい。 In the first aspect of the present invention, an insulator, a high voltage electrode, a ground electrode, and a floating electrode are provided. The high-voltage electrode includes a first exposed portion and a first embedded portion. The floating electrode includes a second exposed portion and a second embedded portion. The first exposed portion and the second exposed portion are exposed to the outside of the insulator. The first embedded portion and the second embedded portion are embedded in the insulator. The second exposed portion is relatively close to the first exposed portion, and the ground electrode is relatively far from the first exposed portion. The capacitance between the high voltage electrode and the floating electrode is relatively small. The capacitance between the floating electrode and the ground electrode is relatively large.

　本発明の第２の局面は、本発明の第１の局面にさらなる事項を付加する。本発明の第２の局面においては、接地電極に収容空間が形成される。碍子は、収容空間に収容される被収容部を備える。第２の被埋設部は、被収容部に埋設される構造物を備える。 The second aspect of the present invention adds further matters to the first aspect of the present invention. In the second aspect of the present invention, an accommodation space is formed in the ground electrode. An insulator is provided with the to-be-accepted part accommodated in accommodation space. The second embedded portion includes a structure embedded in the accommodated portion.

　本発明の第３の局面は、本発明の第２の局面にさらなる事項を付加する。本発明の第３の局面においては、収容空間は、丸孔の内部である。丸孔の内周面は、構造物の周りを一周する。構造物は、管形状部である。管形状部の外周面は丸孔の内周面と対向する。 The third aspect of the present invention adds further matters to the second aspect of the present invention. In the third aspect of the present invention, the accommodation space is inside the round hole. The inner peripheral surface of the round hole goes around the structure. The structure is a tube-shaped part. The outer peripheral surface of the tube-shaped portion is opposed to the inner peripheral surface of the round hole.

　本発明の第４の局面は、本発明の第１から第３までのいずれかの局面にさらなる事項を付加する。本発明の第４の局面においては、碍子に中空空間が形成される。第１の被埋設部は、中空空間の内部に中空保持される被中空保持部を備える。 The fourth aspect of the present invention adds further matters to any one of the first to third aspects of the present invention. In the fourth aspect of the present invention, a hollow space is formed in the insulator. The first embedded portion includes a hollow holding portion that is hollowly held inside the hollow space.

　本発明の第５の局面は、本発明の第１の局面にさらなる事項を付加する。本発明の第５の局面においては、接地電極に収容空間が形成される。碍子は、収容空間の外部へ突出する突出部を備える。第１の露出部及び第２の露出部は、突出部からさらに突出する。 The fifth aspect of the present invention adds further matters to the first aspect of the present invention. In the fifth aspect of the present invention, an accommodation space is formed in the ground electrode. An insulator is provided with the protrusion part which protrudes outside the accommodation space. The first exposed portion and the second exposed portion further protrude from the protruding portion.

　本発明の第６の局面は、本発明の第１から第５までのいずれかの局面にさらなる事項を付加する。本発明の第６の局面においては、第１の露出部及び第２の露出部は、それぞれ、第１の棒先端及び第２の棒先端を有する。 The sixth aspect of the present invention adds further matters to any one of the first to fifth aspects of the present invention. In the sixth aspect of the present invention, the first exposed portion and the second exposed portion have a first rod tip and a second rod tip, respectively.

　本発明の第７の局面は、本発明の第１から第６までのいずれかの局面にさらなる事項を付加する。本発明の第７の局面においては、２個以上の浮遊電極が互いに絶縁される。 The seventh aspect of the present invention adds further matters to any one of the first to sixth aspects of the present invention. In the seventh aspect of the present invention, two or more floating electrodes are insulated from each other.

　本発明の第８の局面は、点火装置に向けられる。本発明の第８の局面においては、本発明の第１の局面の点火プラグ及びパルス電圧印加機構が設けられる。パルス電圧印加機構は、高圧電極と接地電極との間にパルス電圧を印加する。 The eighth aspect of the present invention is directed to an ignition device. In an eighth aspect of the present invention, the spark plug and the pulse voltage application mechanism of the first aspect of the present invention are provided. The pulse voltage application mechanism applies a pulse voltage between the high voltage electrode and the ground electrode.

　本発明の第９の局面は、混合気に点火する方法に向けられる。本発明の第９の局面においては、本発明の第１の局面の点火プラグが準備される。高圧電極と接地電極との間にパルス電圧が印加され、第１の露出部と第２の露出部との間にストリーマ放電が発生させられる。 The ninth aspect of the present invention is directed to a method for igniting an air-fuel mixture. In a ninth aspect of the present invention, a spark plug according to the first aspect of the present invention is prepared. A pulse voltage is applied between the high-voltage electrode and the ground electrode, and streamer discharge is generated between the first exposed portion and the second exposed portion.

　本発明の第１０から第１６までの局面は、点火プラグに向けられる。 The tenth to sixteenth aspects of the present invention are directed to the spark plug.

　本発明の第１０の局面においては、碍子、高圧電極、接地電極及び浮遊電極が設けられる。接地電極は、第１の露出部を備える。高圧電極は、第１の被埋設部を備える。浮遊電極は、第２の露出部及び第２の被埋設部を備える。第１の露出部及び第２の露出部は、碍子の外部に露出する。第１の被埋設部及び第２の被埋設部は、碍子に埋設される。第２の露出部は、第１の露出部に相対的に近い。高圧電極は、第１の露出部から相対的に遠い。高圧電極と浮遊電極との間の静電容量は、相対的に大きい。浮遊電極と接地電極との間の静電容量は、相対的に小さい。 In the tenth aspect of the present invention, an insulator, a high voltage electrode, a ground electrode, and a floating electrode are provided. The ground electrode includes a first exposed portion. The high voltage electrode includes a first embedded portion. The floating electrode includes a second exposed portion and a second embedded portion. The first exposed portion and the second exposed portion are exposed to the outside of the insulator. The first embedded portion and the second embedded portion are embedded in the insulator. The second exposed portion is relatively close to the first exposed portion. The high voltage electrode is relatively far from the first exposed portion. The capacitance between the high voltage electrode and the floating electrode is relatively large. The capacitance between the floating electrode and the ground electrode is relatively small.

　本発明の第１１の局面は、本発明の第１０の局面にさらなる事項を付加する。本発明の第１１の局面においては、第１の被埋設部は、第１の構造物を備える。第２の被埋設部は、第２の構造物を備える。第２の構造物には、内部空間が形成される。碍子は、内部空間に充填される被充填部を備える。第１の構造物は、被充填部に埋設される。 The eleventh aspect of the present invention adds further matters to the tenth aspect of the present invention. In an eleventh aspect of the present invention, the first embedded portion includes a first structure. The second embedded portion includes a second structure. An internal space is formed in the second structure. An insulator is provided with the to-be-filled part with which internal space is filled. The first structure is embedded in the portion to be filled.

　本発明の第１２の局面は、本発明の第１１の局面にさらなる事項を付加する。本発明の第１２の局面においては、第１の構造物は、棒形状部である。第２の構造物は、管形状部である。管形状部は、棒形状部の周りを一周する。 The twelfth aspect of the present invention adds further matters to the eleventh aspect of the present invention. In the twelfth aspect of the present invention, the first structure is a bar-shaped portion. The second structure is a tube-shaped part. The tube-shaped portion goes around the rod-shaped portion.

　本発明の第１３の局面は、本発明の第１０から第１２までのいずれかの局面にさらなる事項を付加する。本発明の第１３の局面においては、接地電極に収容空間が形成される。碍子は、収容空間の内部に中空保持される被中空保持部を備える。 The thirteenth aspect of the present invention adds further matters to any of the tenth to twelfth aspects of the present invention. In the thirteenth aspect of the present invention, an accommodation space is formed in the ground electrode. The insulator includes a hollow holding portion that is hollowly held inside the accommodation space.

　本発明の第１４の局面は、本発明の第１０の局面にさらなる事項を付加する。本発明の第１４の局面においては、接地電極に収容空間が形成される。碍子は、収容空間に収容される被収容部を備える。第２の露出部は、被収容部の外部に突出し、収容空間の外部に突出する。 The fourteenth aspect of the present invention adds further matters to the tenth aspect of the present invention. In the fourteenth aspect of the present invention, an accommodation space is formed in the ground electrode. An insulator is provided with the to-be-accepted part accommodated in accommodation space. The second exposed portion protrudes outside the accommodated portion and protrudes outside the accommodation space.

　本発明の第１５の局面は、本発明の第１０から第１４までのいずれかの局面にさらなる事項を付加する。本発明の第１５の局面においては、第２の露出部は、棒先端を有する。 The fifteenth aspect of the present invention adds further matters to any of the tenth to fourteenth aspects of the present invention. In the fifteenth aspect of the present invention, the second exposed portion has a rod tip.

　本発明の第１６の局面は、本発明の第１０から第１５までのいずれかの局面にさらなる事項を付加する。本発明の第１６の局面においては、２個以上の浮遊電極が互いに絶縁される。 The sixteenth aspect of the present invention adds further matters to any of the tenth to fifteenth aspects of the present invention. In the sixteenth aspect of the present invention, two or more floating electrodes are insulated from each other.

　本発明の第１７の局面は、点火装置に向けられる。本発明の第１７の局面においては、本発明の第１０の局面の点火プラグ及びパルス電圧印加機構が設けられる。パルス電圧印加機構は、高圧電極と接地電極との間にパルス電圧を印加する。 The seventeenth aspect of the present invention is directed to an ignition device. In a seventeenth aspect of the present invention, the spark plug and pulse voltage application mechanism of the tenth aspect of the present invention are provided. The pulse voltage application mechanism applies a pulse voltage between the high voltage electrode and the ground electrode.

　本発明の第１８の局面は、混合気に点火する方法に向けられる。本発明の第１８の局面においては、本発明の第１０の局面の点火プラグが準備される。高圧電極と接地電極との間にパルス電圧が印加され、第１の露出部と第２の露出部との間にストリーマ放電が発生させられる。 The eighteenth aspect of the present invention is directed to a method for igniting an air-fuel mixture. In an eighteenth aspect of the present invention, a spark plug according to the tenth aspect of the present invention is prepared. A pulse voltage is applied between the high-voltage electrode and the ground electrode, and streamer discharge is generated between the first exposed portion and the second exposed portion.

　本発明の第１９の局面は、点火プラグに向けられる。本発明の第１９の局面においては、碍子、高圧電極、接地電極、浮遊電極及びキャパシタが設けられる。高圧電極は、第１の露出部及び被埋設部を備える。浮遊電極は、第２の露出部を備える。第１の露出部及び第２の露出部は、碍子の外部に露出する。被埋設部は、碍子に埋設される。浮遊電極は、高圧電極との間に第１の静電容量を持つ。浮遊電極は、接地電極との間に第２の静電容量を持つ。第２の露出部は、第１の露出部に相対的に近い。接地電極は第１の露出部から相対的に遠い。キャパシタの一方の端子は浮遊電極に電気的に接続される。キャパシタの他方の端子は、接地電極に電気的に接続される。キャパシタは、第３の静電容量を持つ。第２の静電容量と第３の静電容量との和は、第１の静電容量より大きい。キャパシタは、碍子に外付けされる。 The nineteenth aspect of the present invention is directed to a spark plug. In a nineteenth aspect of the present invention, an insulator, a high voltage electrode, a ground electrode, a floating electrode, and a capacitor are provided. The high voltage electrode includes a first exposed portion and an embedded portion. The floating electrode includes a second exposed portion. The first exposed portion and the second exposed portion are exposed to the outside of the insulator. The buried part is buried in the insulator. The floating electrode has a first capacitance between the high-voltage electrode. The floating electrode has a second electrostatic capacitance between the floating electrode and the ground electrode. The second exposed portion is relatively close to the first exposed portion. The ground electrode is relatively far from the first exposed portion. One terminal of the capacitor is electrically connected to the floating electrode. The other terminal of the capacitor is electrically connected to the ground electrode. The capacitor has a third capacitance. The sum of the second capacitance and the third capacitance is larger than the first capacitance. The capacitor is externally attached to the insulator.

　本発明の第１から第９までの局面によれば、高圧電極と接地電極との間に電圧が印加された場合に高圧電極と浮遊電極との間に高圧が誘起される。第１の露出部と第２の露出部との間に強力なストリーマ放電が発生する。放電体積が大きくなり、難燃焼条件であっても混合気に安定して点火できる。また、点火プラグに流れる電流が減少する。単位放電体積あたりの消費エネルギーが減少する。 According to the first to ninth aspects of the present invention, when a voltage is applied between the high voltage electrode and the ground electrode, a high voltage is induced between the high voltage electrode and the floating electrode. A powerful streamer discharge is generated between the first exposed portion and the second exposed portion. The discharge volume increases, and the air-fuel mixture can be ignited stably even under difficult combustion conditions. In addition, the current flowing through the spark plug is reduced. Energy consumption per unit discharge volume is reduced.

　本発明の第２の局面によれば、浮遊電極と接地電極とが広範囲に渡って碍子を挟んで対向する。浮遊電極と接地電極との間の静電容量が大きくなる。 According to the second aspect of the present invention, the floating electrode and the ground electrode are opposed to each other across the insulator over a wide range. The capacitance between the floating electrode and the ground electrode is increased.

　本発明の第３の局面によれば、浮遊電極と接地電極とが対向する範囲が広がり、浮遊電極と接地電極との間の静電容量が大きくなる。 According to the third aspect of the present invention, the range in which the floating electrode and the ground electrode are opposed to each other is widened, and the capacitance between the floating electrode and the ground electrode is increased.

　本発明の第４の局面によれば、碍子の内部で高圧電極が空隙に囲まれ、高圧電極と浮遊電極との間の静電容量が小さくなる。 According to the fourth aspect of the present invention, the high voltage electrode is surrounded by the air gap inside the insulator, and the capacitance between the high voltage electrode and the floating electrode is reduced.

　本発明の第５の局面によれば、第１の露出部及び第２の露出部が接地電極から離れる。第１の露出部と接地電極との間に放電が発生しにくくなり、第２の露出部と接地電極との間に放電が発生しにくくなる。 According to the fifth aspect of the present invention, the first exposed portion and the second exposed portion are separated from the ground electrode. A discharge is less likely to occur between the first exposed portion and the ground electrode, and a discharge is less likely to occur between the second exposed portion and the ground electrode.

　本発明の第６の局面によれば、第１の露出部及び第２の露出部に電界が集中し、第１の露出部と第２の露出部との間に放電が発生しやすくなる。 According to the sixth aspect of the present invention, the electric field concentrates on the first exposed portion and the second exposed portion, and electric discharge is likely to occur between the first exposed portion and the second exposed portion.

　本発明の第７の局面によれば、２個以上の浮遊電極の電位が独立する。高圧電極と一の浮遊電極との間に放電が発生しても高圧電極と他の浮遊電極との間の放電が阻害されず、多点放電が発生しやすくなる。 According to the seventh aspect of the present invention, the potentials of two or more floating electrodes are independent. Even if a discharge occurs between the high-voltage electrode and one floating electrode, the discharge between the high-voltage electrode and another floating electrode is not hindered, and a multipoint discharge is likely to occur.

　本発明の第１０から第１８までの局面によれば、高圧電極と接地電極との間に電圧が印加された場合に浮遊電極と接地電極との間に高圧が誘起される。第１の露出部と第２の露出部との間に強力なストリーマ放電が発生する。放電体積が大きくなり、難燃焼条件であっても混合気に安定して点火できる。また、点火プラグに流れる電流が減少し、単位放電体積あたりの消費エネルギーが減少する。 According to the tenth to eighteenth aspects of the present invention, a high voltage is induced between the floating electrode and the ground electrode when a voltage is applied between the high voltage electrode and the ground electrode. A powerful streamer discharge is generated between the first exposed portion and the second exposed portion. The discharge volume increases, and the air-fuel mixture can be ignited stably even under difficult combustion conditions. In addition, the current flowing through the spark plug is reduced, and the energy consumption per unit discharge volume is reduced.

　本発明の第１１の局面によれば、高圧電極と浮遊電極とが広範囲に渡って碍子を挟んで対向する。高圧電極と浮遊電極との間の静電容量が大きくなる。 According to the eleventh aspect of the present invention, the high voltage electrode and the floating electrode are opposed to each other across the insulator over a wide range. The capacitance between the high voltage electrode and the floating electrode is increased.

　本発明の第１２の局面によれば、中心電極と浮遊電極とが対向する範囲が広がり、中心電極と接地電極との間の静電容量が大きくなる。 According to the twelfth aspect of the present invention, the range in which the center electrode and the floating electrode face each other is widened, and the capacitance between the center electrode and the ground electrode is increased.

　本発明の第１３の局面によれば、収容空間の内部で碍子が空隙に囲まれ、浮遊電極と接地電極との間の静電容量が小さくなる。 According to the thirteenth aspect of the present invention, the insulator is surrounded by the air gap inside the accommodation space, and the capacitance between the floating electrode and the ground electrode is reduced.

　本発明の第１４の局面によれば、第２の露出部が高圧電極から離れ、高圧電極と第２の露出部との間に放電が発生しにくくなる。また、第２の露出部が接地電極から離れ、第２の露出部と接地電極との間に放電が発生しにくくなる。 According to the fourteenth aspect of the present invention, the second exposed portion is separated from the high voltage electrode, and it is difficult for discharge to occur between the high voltage electrode and the second exposed portion. In addition, the second exposed portion is separated from the ground electrode, and discharge is less likely to occur between the second exposed portion and the ground electrode.

　本発明の第１５の局面によれば、第２の露出部に電界が集中し、第１の露出部と第２の露出部との間に放電が発生しやすくなる。 According to the fifteenth aspect of the present invention, the electric field concentrates on the second exposed portion, and electric discharge is likely to occur between the first exposed portion and the second exposed portion.

　本発明の第１６の局面によれば、２個以上の浮遊電極の電位が独立し、一の浮遊電極と接地電極との間に放電が発生しても他の浮遊電極と接地電極との間の放電が阻害されず、多点放電が発生しやすくなる。 According to the sixteenth aspect of the present invention, the potentials of two or more floating electrodes are independent, and even if a discharge occurs between one floating electrode and the ground electrode, Is not hindered, and multi-point discharge is likely to occur.

　本発明の第１９の局面によれば、高圧電極と接地電極との間に電圧が印加された場合に高圧電極と浮遊電極との間に高圧が誘起される。第１の露出部と第２の露出部との間に強力なストリーマ放電が発生する。放電体積が大きくなり、難燃焼条件であっても混合気に安定して点火できる。また、点火プラグに流れる電流が減少する。単位放電体積あたりの消費エネルギーが減少する。 According to the nineteenth aspect of the present invention, when a voltage is applied between the high voltage electrode and the ground electrode, a high voltage is induced between the high voltage electrode and the floating electrode. A powerful streamer discharge is generated between the first exposed portion and the second exposed portion. The discharge volume increases, and the air-fuel mixture can be ignited stably even under difficult combustion conditions. In addition, the current flowing through the spark plug is reduced. Energy consumption per unit discharge volume is reduced.

　これらの及びこれら以外の本発明の目的、特徴、局面及び利点は、添付図面とともに考慮されたときに下記の本発明の詳細な説明によってより明白となる。 These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when considered in conjunction with the accompanying drawings.

第１実施形態の点火装置及び燃焼容器の模式図である。It is a schematic diagram of the ignition device and combustion container of 1st Embodiment. 第１実施形態の点火プラグの斜視図である。It is a perspective view of the spark plug of 1st Embodiment. 第１実施形態の点火プラグの断面図である。It is sectional drawing of the ignition plug of 1st Embodiment. 第１実施形態の碍子の分解斜視図である。It is a disassembled perspective view of the insulator of 1st Embodiment. 第１実施形態の浮遊電極の斜視図である。It is a perspective view of the floating electrode of 1st Embodiment. 第１実施形態の電極の位置の関係を示す模式図である。It is a schematic diagram which shows the positional relationship of the electrode of 1st Embodiment. 第１実施形態の点火プラグの等価回路の回路図である。It is a circuit diagram of the equivalent circuit of the ignition plug of 1st Embodiment. 放電前の電圧の波形のグラフである。It is a graph of the waveform of the voltage before discharge. 放電後の電圧の波形のグラフである。It is a graph of the waveform of the voltage after discharge. 第２実施形態の点火プラグの斜視図である。It is a perspective view of the ignition plug of 2nd Embodiment. 第２実施形態の点火プラグの断面図である。It is sectional drawing of the ignition plug of 2nd Embodiment. 第２実施形態の碍子の分解斜視図である。It is a disassembled perspective view of the insulator of 2nd Embodiment. 第２実施形態の浮遊電極の斜視図である。It is a perspective view of the floating electrode of 2nd Embodiment. 第３実施形態の点火プラグの斜視図である。It is a perspective view of the ignition plug of 3rd Embodiment. 第３実施形態の点火プラグの断面図である。It is sectional drawing of the ignition plug of 3rd Embodiment. 第３実施形態の電極の位置の関係を示す模式図である。It is a schematic diagram which shows the positional relationship of the electrode of 3rd Embodiment. 第３実施形態の点火プラグの等価回路の回路図である。It is a circuit diagram of the equivalent circuit of the ignition plug of 3rd Embodiment. 第４実施形態の点火プラグの斜視図である。It is a perspective view of the ignition plug of 4th Embodiment. 第４実施形態の点火プラグの断面図である。It is sectional drawing of the ignition plug of 4th Embodiment. 第４実施形態の碍子の分解斜視図である。It is a disassembled perspective view of the insulator of 4th Embodiment. 第４実施形態の浮遊電極の斜視図である。It is a perspective view of the floating electrode of 4th Embodiment. 第５実施形態の点火プラグの斜視図である。It is a perspective view of the ignition plug of 5th Embodiment. 第５実施形態の点火プラグの断面図である。It is sectional drawing of the ignition plug of 5th Embodiment. 第５実施形態の碍子の分解斜視図である。It is a disassembled perspective view of the insulator of 5th Embodiment. 第５実施形態の浮遊電極の斜視図である。It is a perspective view of the floating electrode of 5th Embodiment. 第５実施形態の電極の位置の関係を示す模式図である。It is a schematic diagram which shows the positional relationship of the electrode of 5th Embodiment. 第５実施形態の浮遊電極の変形例を示す斜視図である。It is a perspective view which shows the modification of the floating electrode of 5th Embodiment. 第６実施形態の点火プラグの斜視図である。It is a perspective view of the ignition plug of 6th Embodiment. 第６実施形態の点火プラグの等価回路である。It is an equivalent circuit of the spark plug of 6th Embodiment. 浮遊電極の変形例を示す斜視図である。It is a perspective view which shows the modification of a floating electrode. 浮遊電極の変形例を示す斜視図である。It is a perspective view which shows the modification of a floating electrode. 浮遊電極の変形例を示す斜視図である。It is a perspective view which shows the modification of a floating electrode. 圧力及び電圧による放電の形態の変化を示すグラフである。It is a graph which shows the change of the form of discharge by pressure and voltage.

　｛第１実施形態｝
　（概略）
　第１実施形態は、点火プラグ、点火装置及び混合気に点火する方法に関する。 {First embodiment}
(Outline)
The first embodiment relates to a spark plug, an ignition device, and a method for igniting an air-fuel mixture.

　図１の模式図は、第１実施形態の点火装置及び燃焼容器を示す。図２の模式図は、第１実施形態の点火プラグの斜視図である。図３の模式図は、第１実施形態の点火プラグの断面図である。図４の模式図は、第１実施形態の碍子の分解斜視図である。図５の模式図は、第１実施形態の浮遊電極の斜視図である。 1 schematically shows the ignition device and the combustion container of the first embodiment. The schematic diagram of FIG. 2 is a perspective view of the ignition plug of the first embodiment. The schematic diagram of FIG. 3 is a cross-sectional view of the spark plug of the first embodiment. The schematic diagram of FIG. 4 is an exploded perspective view of the insulator of the first embodiment. The schematic diagram of FIG. 5 is a perspective view of the floating electrode of the first embodiment.

　図１に示すように、点火装置１０００は、点火プラグ１０１０及びパルス電圧印加機構１０１２を備える。点火プラグ１０１０は、燃焼容器９０００に取り付けられる。燃焼容器９０００には、燃焼室９００２が形成される。燃焼室９００２は、混合気で満たされる。 As shown in FIG. 1, the ignition device 1000 includes an ignition plug 1010 and a pulse voltage application mechanism 1012. The spark plug 1010 is attached to the combustion container 9000. A combustion chamber 9002 is formed in the combustion container 9000. Combustion chamber 9002 is filled with an air-fuel mixture.

　図２及び図３に示すように、点火プラグ１０１０は、碍子１０２０、中心電極１０２２、主体金具１０２４及び浮遊電極１０２６を備える。中心電極１０２２は、露出部１０３０及び被埋設部１０３２を備える。浮遊電極１０２６は、露出部１０４０及び被埋設部１０４２を備える。中心電極１０２２の被埋設部１０３２は、高圧が印加される中心電極１０２２を絶縁するために設けられる。浮遊電極１０２６の被埋設部１０４２は、浮遊電極１０２６と主体金具１０２４との間の静電容量Ｃ２を大きくするために設けられる。 2 and 3, the spark plug 1010 includes an insulator 1020, a center electrode 1022, a metal shell 1024, and a floating electrode 1026. The center electrode 1022 includes an exposed portion 1030 and an embedded portion 1032. The floating electrode 1026 includes an exposed portion 1040 and an embedded portion 1042. The embedded portion 1032 of the center electrode 1022 is provided to insulate the center electrode 1022 to which a high voltage is applied. The embedded portion 1042 of the floating electrode 1026 is provided to increase the capacitance C2 between the floating electrode 1026 and the metal shell 1024.

　パルス電圧印加機構１０１２は、中心電極１０２２と主体金具１０２４との間にパルス電圧を印加する。中心電極１０２２には高圧が印加され、中心電極１０２２は高圧電極となる。主体金具１０２４は、接地され、接地電極となる。 The pulse voltage application mechanism 1012 applies a pulse voltage between the center electrode 1022 and the metal shell 1024. A high voltage is applied to the center electrode 1022, and the center electrode 1022 becomes a high voltage electrode. The metal shell 1024 is grounded and becomes a ground electrode.

　浮遊電極１０２６の露出部１０４０は中心電極１０２２の露出部１０３０に相対的に近く、主体金具１０２４は中心電極１０２２の露出部１０３０から相対的に遠い。中心電極１０２２と浮遊電極１０２６との間の静電容量Ｃ１は相対的に小さく、浮遊電極１０２６と主体金具１０２４との間の静電容量Ｃ２は相対的に大きい。 The exposed portion 1040 of the floating electrode 1026 is relatively close to the exposed portion 1030 of the center electrode 1022, and the metal shell 1024 is relatively far from the exposed portion 1030 of the center electrode 1022. The capacitance C1 between the center electrode 1022 and the floating electrode 1026 is relatively small, and the capacitance C2 between the floating electrode 1026 and the metal shell 1024 is relatively large.

　中心電極１０２２と主体金具１０２４との間にパルス電圧が印加された場合は、中心電極１０２２と浮遊電極１０２６との間に高圧が誘起され、中心電極１０２２の露出部１０３０と浮遊電極１０２６の露出部１０４０との間に強力なストリーマ放電が発生する。この強力なストリーマ放電により、混合気が点火される。 When a pulse voltage is applied between the center electrode 1022 and the metal shell 1024, a high voltage is induced between the center electrode 1022 and the floating electrode 1026, and the exposed portion 1030 of the center electrode 1022 and the exposed portion of the floating electrode 1026. A strong streamer discharge is generated between 1040 and 1040. This powerful streamer discharge ignites the air-fuel mixture.

　強力なストリーマ放電の放電体積は大きい。このため、強力なストリーマ放電により混合気が点火される場合は、希薄燃焼が行われる場合等の難燃焼条件であっても混合気に安定して点火できる。また、強力なストリーマ放電により混合気が点火される場合は、アーク放電により混合気が点火される場合と比較して、点火プラグ１０１０に流れる電流が減少する。このため、強力なストリーマ放電により混合気が点火される場合は、単位放電体積あたりの消費エネルギーが減少する。 The discharge volume of powerful streamer discharge is large. For this reason, when the air-fuel mixture is ignited by strong streamer discharge, the air-fuel mixture can be stably ignited even under difficult combustion conditions such as when lean combustion is performed. Further, when the air-fuel mixture is ignited by strong streamer discharge, the current flowing through the spark plug 1010 is reduced as compared with the case where the air-fuel mixture is ignited by arc discharge. For this reason, when the air-fuel mixture is ignited by a powerful streamer discharge, the energy consumption per unit discharge volume is reduced.

　（電極の位置の関係）
　図６の模式図は、第１実施形態の電極の位置の関係を示す。 (Relationship of electrode position)
The schematic diagram of FIG. 6 shows the positional relationship of the electrodes of the first embodiment.

　図６に示すように、浮遊電極１０２６の露出部１０４０は中心電極１０２２の露出部１０３０に相対的に近く、主体金具１０２４は中心電極１０２２の露出部１０３０から相対的に遠い。したがって、浮遊電極１０２６の露出部１０４０から燃焼室９００２を経由して中心電極１０２２の露出部１０３０までの放電経路長Ｌ１は相対的に短く、主体金具１０２４から燃焼室９００２を経由して中心電極１０２２の露出部１０３０までの放電経路長Ｌ２は相対的に長く、Ｌ１＜Ｌ２が成立する。中心電極１０２２の露出部１０３０と浮遊電極１０２６の露出部１０４０との放電ギャップは、中心電極１０２２の露出部１０３０と主体金具１０２４との放電ギャップより狭い。このため、中心電極１０２２の露出部１０３０と主体金具１０２４との間には相対的に放電が発生しにくい。また、中心電極１０２２の露出部１０３０と浮遊電極１０２６の露出部１０４０との間には相対的に放電が発生しやすい。 As shown in FIG. 6, the exposed portion 1040 of the floating electrode 1026 is relatively close to the exposed portion 1030 of the center electrode 1022, and the metal shell 1024 is relatively far from the exposed portion 1030 of the center electrode 1022. Accordingly, the discharge path length L1 from the exposed portion 1040 of the floating electrode 1026 to the exposed portion 1030 of the center electrode 1022 via the combustion chamber 9002 is relatively short, and the center electrode 1022 passes from the metal shell 1024 via the combustion chamber 9002. The discharge path length L2 to the exposed portion 1030 is relatively long, and L1 <L2 is established. The discharge gap between the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026 is narrower than the discharge gap between the exposed portion 1030 of the center electrode 1022 and the metal shell 1024. For this reason, a discharge is relatively unlikely to occur between the exposed portion 1030 of the center electrode 1022 and the metal shell 1024. Further, a discharge is relatively easily generated between the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026.

　この電極の位置の関係を実現するため、図２及び図３に示すように、浮遊電極１０２６は、中心電極１０２２と主体金具１０２４との中間に配置される。点火プラグ１０１０の軸方向から見て、中心電極１０２２は点火プラグ１０１０の中心軸上にあり、主体金具１０２４は中心電極１０２２を囲む。点火プラグ１０１０の軸方向から見て、浮遊電極１０２６は中心電極１０２２と主体金具１０２４との間に設置され、浮遊電極１０２６は中心電極１０２２及び主体金具１０２４から離される。点火プラグ１０１０の軸方向から見て浮遊電極１０２６が中心電極１０２２に重なる場合は、中心電極１０２２と浮遊電極１０２６とは点火プラグ１０１０の軸方向に離される。点火プラグ１０１０の軸方向から見て浮遊電極１０２６が主体金具１０２４に重なる場合は、浮遊電極１０２６と主体金具１０２４とは点火プラグ１０１０の軸方向に離される。 In order to realize the positional relationship of the electrodes, the floating electrode 1026 is disposed between the center electrode 1022 and the metal shell 1024 as shown in FIGS. When viewed from the axial direction of the spark plug 1010, the center electrode 1022 is on the center axis of the spark plug 1010, and the metal shell 1024 surrounds the center electrode 1022. When viewed from the axial direction of the spark plug 1010, the floating electrode 1026 is installed between the center electrode 1022 and the metal shell 1024, and the floating electrode 1026 is separated from the center electrode 1022 and the metal shell 1024. When the floating electrode 1026 overlaps the center electrode 1022 when viewed from the axial direction of the spark plug 1010, the center electrode 1022 and the floating electrode 1026 are separated from each other in the axial direction of the spark plug 1010. When the floating electrode 1026 overlaps the metallic shell 1024 when viewed from the axial direction of the spark plug 1010, the floating electrode 1026 and the metallic shell 1024 are separated from each other in the axial direction of the spark plug 1010.

　（静電容量の関係）
　図７の回路図は、第１実施形態の点火プラグの等価回路を示す。 (Capacitance relationship)
The circuit diagram of FIG. 7 shows an equivalent circuit of the spark plug of the first embodiment.

　中心電極１０２２、主体金具１０２４及び浮遊電極１０２６は、碍子１０２０により互いに絶縁される。図７に示すように、中心電極１０２２と主体金具１０２４との間に電圧Ｖが印加された場合には、中心電極１０２２と浮遊電極１０２６との間の電圧Ｖ１及び浮遊電極１０２６と主体金具１０２４との間の電圧Ｖ２に電圧Ｖが分圧され、Ｖ＝Ｖ１＋Ｖ２が成立する。電圧Ｖ１及びＶ２は、それぞれ、式（１）及び（２）によりあらわされる。 The center electrode 1022, the metal shell 1024, and the floating electrode 1026 are insulated from each other by the insulator 1020. As shown in FIG. 7, when a voltage V is applied between the center electrode 1022 and the metal shell 1024, the voltage V1 between the center electrode 1022 and the floating electrode 1026, the floating electrode 1026 and the metal shell 1024, The voltage V is divided into the voltage V2 between the two, and V = V1 + V2 is established. The voltages V1 and V2 are expressed by equations (1) and (2), respectively.

Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001

　中心電極１０２２と浮遊電極１０２６との間の静電容量Ｃ１が小さく浮遊電極１０２６と主体金具１０２４との間の静電容量Ｃ２が大きい場合は中心電極１０２２と浮遊電極１０２６との間の電圧Ｖ１が高く浮遊電極１０２６と主体金具１０２４との間の電圧Ｖ２が低いことが式（１）及び式（２）から導かれる。このため、Ｃ１＜Ｃ２が成立する場合はＶ２＜Ｖ１が成立し、中心電極１０２２と主体金具１０２４との間にパルス電圧が印加された場合に中心電極１０２２と浮遊電極１０２６との間に高圧が誘起される。これにより、浮遊電極１０２６の露出部１０４０と主体金具１０２４との間に放電が発生しにくくなり、中心電極１０２２の露出部１０３０と浮遊電極１０２６の露出部１０４０との間に放電が発生しやすくなる。静電容量Ｃ２は、少なくとも静電容量Ｃ１より大きく、望ましくは静電容量Ｃ１の１０倍以上である。 When the electrostatic capacitance C1 between the center electrode 1022 and the floating electrode 1026 is small and the electrostatic capacitance C2 between the floating electrode 1026 and the metal shell 1024 is large, the voltage V1 between the central electrode 1022 and the floating electrode 1026 is It can be derived from the equations (1) and (2) that the voltage V2 between the floating electrode 1026 and the metal shell 1024 is high and low. Therefore, when C1 <C2 is satisfied, V2 <V1 is satisfied, and when a pulse voltage is applied between the center electrode 1022 and the metal shell 1024, a high voltage is generated between the center electrode 1022 and the floating electrode 1026. Induced. As a result, a discharge is less likely to occur between the exposed portion 1040 of the floating electrode 1026 and the metal shell 1024, and a discharge is likely to occur between the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026. . The electrostatic capacity C2 is at least larger than the electrostatic capacity C1, and preferably 10 times or more of the electrostatic capacity C1.

　（放電の発生の識別）
　図８及び図９のグラフは、中心電極１０２２と主体金具１０２４との間の電圧Ｖ及び浮遊電極１０２６と主体金具１０２４との間の電圧Ｖ２の波形を示す。図８は、放電前の波形を示す。図９は、放電後の波形を示す。 (Identification of discharge occurrence)
The graphs of FIGS. 8 and 9 show waveforms of the voltage V between the center electrode 1022 and the metal shell 1024 and the voltage V2 between the floating electrode 1026 and the metal shell 1024. FIG. 8 shows a waveform before discharge. FIG. 9 shows the waveform after discharge.

　図８に示すように、放電前においては、中心電極１０２２と主体金具１０２４との間にパルス電圧が印加され中心電極１０２２と主体金具１０２４との間の電圧Ｖが上昇した場合であっても、浮遊電極１０２６と主体金具１０２４との間の電圧Ｖ２は電圧Ｖと同程度まで上昇しない。これに対して、図９に示すように、放電後においては、中心電極１０２２と主体金具１０２４との間にパルス電圧が印加され電圧Ｖが上昇した場合には、電圧Ｖ２も電圧Ｖと同程度まで上昇する。したがって、放電の発生の有無は、電圧Ｖ及びＶ２により識別される。点火プラグ１０１０の軸方向先端側をカメラで撮影することにより放電の発生の有無が識別されてもよい。 As shown in FIG. 8, even before the discharge, even when the pulse voltage is applied between the center electrode 1022 and the metal shell 1024 and the voltage V between the center electrode 1022 and the metal shell 1024 increases, The voltage V2 between the floating electrode 1026 and the metal shell 1024 does not rise to the same extent as the voltage V. On the other hand, as shown in FIG. 9, after the discharge, when a pulse voltage is applied between the center electrode 1022 and the metal shell 1024 and the voltage V rises, the voltage V2 is about the same as the voltage V. To rise. Therefore, the presence or absence of occurrence of discharge is identified by the voltages V and V2. The presence or absence of occurrence of discharge may be identified by photographing the tip end side of the spark plug 1010 in the axial direction with a camera.

　（放電の強弱の調整）
　点火プラグ１０１０に流れる電流ｉは、式（３）によりあらわされる。電流ｉは、中心電極１０２２と浮遊電極１０２６との間の静電容量Ｃ１及び浮遊電極１０２６と主体金具１０２４との間の静電容量Ｃ２の合成静電容量と、中心電極１０２２と主体金具１０２４との間の電圧Ｖの立ち上がりの速さとの積であらわされる。 (Adjustment of discharge intensity)
The current i flowing through the spark plug 1010 is expressed by the equation (3). The current i is composed of the capacitance C1 between the center electrode 1022 and the floating electrode 1026 and the combined capacitance C2 between the floating electrode 1026 and the metal shell 1024, and the center electrode 1022 and the metal shell 1024. Is expressed by the product of the rising speed of the voltage V during

Figure JPOXMLDOC01-appb-M000002
Figure JPOXMLDOC01-appb-M000002

　中心電極１０２２と浮遊電極１０２６との間の静電容量Ｃ１及び浮遊電極１０２６と主体金具１０２４との間の静電容量Ｃ２が大きい場合は点火プラグ１０１０に流れる電流ｉが多いことが式（３）から導かれる。このため、静電容量Ｃ１及びＣ２は、強力なストリーマ放電を発生させるのに十分な電流が点火プラグ１０１０に流れる適正値に決められる。放電を強くすることが望まれる場合は静電容量Ｃ１及びＣ２が大きくされ、放電を弱くすることが望まれる場合は静電容量Ｃ１及びＣ２が小さくされる。放電を弱くすることが望まれる場合は、例えば、電極の消耗を抑制することが望まれる場合である。 When the capacitance C1 between the center electrode 1022 and the floating electrode 1026 and the capacitance C2 between the floating electrode 1026 and the metal shell 1024 are large, the current i flowing through the spark plug 1010 is often large. Derived from. For this reason, the capacitances C1 and C2 are determined to be appropriate values at which a current sufficient to generate a strong streamer discharge flows through the spark plug 1010. If it is desired to increase the discharge, the capacitances C1 and C2 are increased. If it is desired to decrease the discharge, the capacitances C1 and C2 are decreased. The case where it is desired to weaken the discharge is, for example, the case where suppression of electrode consumption is desired.

　（露出部及び被埋設部）
　図３に示すように、中心電極１０２２の露出部１０３０及び浮遊電極１０２６の露出部１０４０は、碍子１０２０の外部に露出し、燃焼室９００２に露出する。これにより、燃焼室９００２に放電が発生し、放電により混合気に点火できる。中心電極１０２２の被埋設部１０３２及び浮遊電極１０２６の被埋設部１０４２は、碍子１０２０に埋設される。中心電極１０２２の被埋設部１０３２及び浮遊電極１０２６の被埋設部１０４２は、放電の始点又は終点になりにくい。このため、専ら中心電極１０２２の露出部１０３０と浮遊電極１０２６の露出部１０４０との間に放電が発生する。 (Exposed part and buried part)
As shown in FIG. 3, the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026 are exposed to the outside of the insulator 1020 and exposed to the combustion chamber 9002. Thereby, a discharge is generated in the combustion chamber 9002, and the mixture can be ignited by the discharge. The embedded portion 1032 of the center electrode 1022 and the embedded portion 1042 of the floating electrode 1026 are embedded in the insulator 1020. The embedded portion 1032 of the center electrode 1022 and the embedded portion 1042 of the floating electrode 1026 are unlikely to become the start point or end point of discharge. For this reason, a discharge is generated exclusively between the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026.

　中心電極１０２２の露出部１０３０の数が増減されてもよい。浮遊電極１０２６の露出部１０４０の数が２個以上に増やされてもよい。 The number of exposed portions 1030 of the center electrode 1022 may be increased or decreased. The number of exposed portions 1040 of the floating electrode 1026 may be increased to two or more.

　（主体金具）
　図３に示すように、主体金具１０２４には、丸孔１０６０が形成される。図３においては、丸孔１０６０を他の構成物から識別しやすくするために、碍子１０２０の一部が破断線により便宜的に消去されている。丸孔１０６０の内部は、碍子１０２０等を収容する収容空間になる。主体金具１０２４が、「主体金具」とは呼びがたい形状物に置き換えられてもよい。例えば、主体金具１０２４が、丸孔１０６０が形成された板、棒、直方体等の立体物に置き換えられてもよい。丸孔１０６０が他の形状を持つ孔に置き換えられてもよい。 (Main metal fittings)
As shown in FIG. 3, a round hole 1060 is formed in the metal shell 1024. In FIG. 3, in order to make it easy to distinguish the round hole 1060 from other components, a part of the insulator 1020 is conveniently deleted by a broken line. The inside of the round hole 1060 is an accommodation space for accommodating the insulator 1020 and the like. The metal shell 1024 may be replaced with a shape that is difficult to call a “metal metal”. For example, the metal shell 1024 may be replaced with a three-dimensional object such as a plate, a rod, or a rectangular parallelepiped in which the round hole 1060 is formed. The round hole 1060 may be replaced with a hole having another shape.

　主体金具１０２４の外周面１０７０の全部又は一部が絶縁体で被覆されてもよい。主体金具１０２４の全部又は一部が碍子１０２０に埋設されてもよい。 All or part of the outer peripheral surface 1070 of the metal shell 1024 may be covered with an insulator. All or part of the metal shell 1024 may be embedded in the insulator 1020.

　（碍子）
　図３に示すように、碍子１０２０は、被収容部１０８０及び突出部１０８２を備える。被収容部１０８０は、丸孔１０６０の内部に収容される。突出部１０８２は、丸孔１０６０の外部へ突出し、主体金具１０２４から離れる。突出部１０８２は、点火プラグ１０１０の軸方向先端側に突出し、燃焼空間９００２に露出する。 (insulator)
As shown in FIG. 3, the insulator 1020 includes a accommodated portion 1080 and a protruding portion 1082. The accommodated portion 1080 is accommodated inside the round hole 1060. The protruding portion 1082 protrudes outside the round hole 1060 and is separated from the metal shell 1024. The protruding portion 1082 protrudes to the axial front end side of the spark plug 1010 and is exposed to the combustion space 9002.

　（浮遊電極の被埋設部による静電容量Ｃ２の増加）
　浮遊電極１０２６の露出部１０４０が中心電極１０２２の露出部１０３０に近づけられ、主体金具１０２４が中心電極１０２２の露出部１０３０から遠ざけられる場合は、中心電極１０２２と浮遊電極１０２６との間の静電容量Ｃ１が大きくなりやすく、浮遊電極１０２６と主体金具１０２４との間の静電容量Ｃ２が小さくなりやすい。このため、静電容量の関係Ｃ１＜Ｃ２が満たされるように浮遊電極１０２６に被埋設部１０４２が設けられる。 (Increase in capacitance C2 due to the buried part of the floating electrode)
When the exposed portion 1040 of the floating electrode 1026 is brought close to the exposed portion 1030 of the center electrode 1022 and the metal shell 1024 is moved away from the exposed portion 1030 of the center electrode 1022, the capacitance between the center electrode 1022 and the floating electrode 1026 C1 tends to increase, and the capacitance C2 between the floating electrode 1026 and the metal shell 1024 tends to decrease. Therefore, the embedded portion 1042 is provided in the floating electrode 1026 so that the capacitance relationship C1 <C2 is satisfied.

　図３及び図５に示すように、浮遊電極１０２６は、管形状部１１２０から棒体１８０２が伸びる構造を有する。棒体１８０２の軸方向先端側が浮遊電極１０２６の露出部１０４０となる。棒体１８０２の軸方向後端側及び管形状部１１２０が浮遊電極１０２６の被埋設部１０４２となる。浮遊電極１０２６の被埋設部１０４２は、管形状部１１２０及び棒形状部１１２２を備える。管形状部１１２０は、丸孔１０６０の内部に配置され、被収容部１０８０に埋設される。丸孔１０６０の内周面１１８０は、管形状部１１２０の周りを一周する。丸孔１０６０の内周面１１８０と管形状部１１２０の外周面１１７０とは、対向する。これにより、浮遊電極１０２６と主体金具１０２４とが広範囲に渡って碍子１０２０を挟んで対向する。このため、浮遊電極１０２６と主体金具１０２４との間の静電容量Ｃ２が大きくなる。管形状部１１２０と主体金具１０２４との間隙には、碍子１０２０が充填される。当該間隙には、望ましくは、空隙が存在しない。ただし、当該間隙に若干の空隙が存在してもよい。 3 and 5, the floating electrode 1026 has a structure in which a rod 1802 extends from the tube-shaped portion 1120. The tip end side in the axial direction of the rod body 1802 becomes the exposed portion 1040 of the floating electrode 1026. The rear end side in the axial direction of the rod body 1802 and the tube-shaped portion 1120 serve as the embedded portion 1042 of the floating electrode 1026. The embedded portion 1042 of the floating electrode 1026 includes a tube-shaped portion 1120 and a rod-shaped portion 1122. The tubular portion 1120 is disposed inside the round hole 1060 and is embedded in the accommodated portion 1080. The inner peripheral surface 1180 of the round hole 1060 makes a round around the tube-shaped portion 1120. The inner peripheral surface 1180 of the round hole 1060 and the outer peripheral surface 1170 of the tube-shaped portion 1120 face each other. Thereby, the floating electrode 1026 and the metal shell 1024 face each other across the insulator 1020 over a wide range. For this reason, the capacitance C2 between the floating electrode 1026 and the metal shell 1024 increases. A gap between the tubular portion 1120 and the metal shell 1024 is filled with an insulator 1020. The gap is desirably free of voids. However, a slight gap may exist in the gap.

　管形状部１１２０が設けられることには、浮遊電極１０２６と主体金具１０２４と対向する範囲が広がり、浮遊電極１０２６と主体金具１０２４との間の静電容量Ｃ２が大きくなるという利点がある。しかし、管形状部１１２０に代えて、又は、管形状部１１２０に加えて、主体金具１０２４との間に大きな静電容量を形成する構造物が設けられてもよい。例えば、多数の棒形状部、コイル形状部、板形状部等が設けられてもよい。 The provision of the tube-shaped portion 1120 has an advantage that a range in which the floating electrode 1026 and the metal shell 1024 are opposed to each other is widened, and the capacitance C2 between the floating electrode 1026 and the metal shell 1024 is increased. However, instead of the tube-shaped portion 1120 or in addition to the tube-shaped portion 1120, a structure that forms a large capacitance with the metal shell 1024 may be provided. For example, many rod-shaped parts, coil-shaped parts, plate-shaped parts, etc. may be provided.

　管形状部１１２０と丸孔１０６０とは同軸配置される。これにより、管形状部１１２０の外周面１１７０から丸孔１０６０の内周面１１８０までの距離が均一になり、電界の偏りが抑制される。 The tube-shaped part 1120 and the round hole 1060 are arranged coaxially. Thereby, the distance from the outer peripheral surface 1170 of the tube-shaped part 1120 to the inner peripheral surface 1180 of the round hole 1060 becomes uniform, and the bias of the electric field is suppressed.

　（露出部の突出）
　図３に示すように、中心電極１０２２の露出部１０３０及び浮遊電極１０２６の露出部１０４０は、突出部１０８２の先端からさらに突出する。中心電極１０２２の露出部１０３０及び浮遊電極１０２６の露出部１０４０は、点火プラグ１０１０の軸方向先端側に突出し、燃焼空間９００２に露出する。中心電極１０２２の露出部１０３０及び浮遊電極１０２６の露出部１０４０は、主体金具１０２４から離れる。これにより、中心電極１０２２の露出部１０３０と主体金具１０２４との間に放電が発生しにくくなり、浮遊電極１０２６の露出部１０４０と主体金具１０２４との間に放電が発生しにくくなる。 (Protrusion of exposed part)
As shown in FIG. 3, the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026 further protrude from the tip of the protruding portion 1082. An exposed portion 1030 of the center electrode 1022 and an exposed portion 1040 of the floating electrode 1026 protrude to the axial front end side of the spark plug 1010 and are exposed to the combustion space 9002. The exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026 are separated from the metal shell 1024. This makes it difficult for discharge to occur between the exposed portion 1030 of the center electrode 1022 and the metal shell 1024, and makes it difficult for discharge to occur between the exposed portion 1040 of the floating electrode 1026 and the metal shell 1024.

　（中心電極及び浮遊電極の露出部の棒先端）
　図２及び図３に示すように、中心電極１０２２の露出部１０３０は、棒形状を持ち、棒先端１０５０を有する。浮遊電極１０２６の露出部１０４０も、棒形状を持ち、棒先端１０５２を有する。これにより、中心電極１０２２の露出部１０３０及び浮遊電極１０２６の露出部１０４０に電界が集中し、中心電極１０２２の露出部１０３０と浮遊電極１０２６の露出部１０４０との間に放電が発生しやすくなる。ただし、中心電極１０２２の露出部１０３０及び浮遊電極１０２６の露出部１０４０が他の形状を持ってもよい。例えば、中心電極１０２２の露出部１０３０が半球形状を持ってもよい。浮遊電極１０２６の露出部１０４０が中心電極１０２２の露出部１０３０を囲む管形状を持ってもよい。 (Bar tip of exposed part of center electrode and floating electrode)
As shown in FIGS. 2 and 3, the exposed portion 1030 of the center electrode 1022 has a rod shape and has a rod tip 1050. The exposed portion 1040 of the floating electrode 1026 also has a rod shape and has a rod tip 1052. As a result, the electric field concentrates on the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026, and electric discharge is likely to occur between the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026. However, the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026 may have other shapes. For example, the exposed portion 1030 of the center electrode 1022 may have a hemispherical shape. The exposed portion 1040 of the floating electrode 1026 may have a tube shape surrounding the exposed portion 1030 of the center electrode 1022.

　中心電極１０２２の露出部１０３０の棒先端１０５０は、平面である。ただし、中心電極１０２２の露出部１０３０の棒先端１０５０が平面でなくてもよい。例えば、中心電極１０２２の露出部１０３０の棒先端１０５０が、球面等であってもよい。 The rod tip 1050 of the exposed portion 1030 of the center electrode 1022 is a plane. However, the rod tip 1050 of the exposed portion 1030 of the center electrode 1022 may not be flat. For example, the rod tip 1050 of the exposed portion 1030 of the center electrode 1022 may be a spherical surface or the like.

　中心電極１０２２の露出部１０３０は、点火プラグ１０１０の軸方向に延在する。浮遊電極１０２６の露出部１０４０の根元側は点火プラグ１０１０の軸方向に延在し、浮遊電極１０２６の露出部１０４０の先端側は点火プラグ１０１０の径方向に延在する。 The exposed portion 1030 of the center electrode 1022 extends in the axial direction of the spark plug 1010. The root side of the exposed portion 1040 of the floating electrode 1026 extends in the axial direction of the spark plug 1010, and the tip side of the exposed portion 1040 of the floating electrode 1026 extends in the radial direction of the spark plug 1010.

　浮遊電極１０２６の露出部１０４０の棒先端１０５２は、点火プラグ１０１０の径方向内側を向く。これにより、浮遊電極１０２６の露出部１０４０の棒先端１０５２が中心電極１０２２に近づく方向を向き、中心電極１０２２の露出部１０３０と浮遊電極１０２６の露出部１０４０との間に放電が発生しやすくなる。ただし、浮遊電極１０２６の露出部１０４０の棒先端１０５２が他の方向を向いてもよい。例えば、浮遊電極１０２６の露出部１０４０の棒先端１０５２が点火プラグ１０１０の軸方向先端側を向いてもよい。 The rod tip 1052 of the exposed portion 1040 of the floating electrode 1026 faces the radially inner side of the spark plug 1010. As a result, the rod tip 1052 of the exposed portion 1040 of the floating electrode 1026 faces in the direction approaching the center electrode 1022, and discharge is likely to occur between the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026. However, the rod tip 1052 of the exposed portion 1040 of the floating electrode 1026 may face another direction. For example, the rod tip 1052 of the exposed portion 1040 of the floating electrode 1026 may face the tip side of the spark plug 1010 in the axial direction.

　中心電極１０２２の露出部１０３０の根元側が点火プラグ１０１０の軸方向に延在し、中心電極１０２２の露出部１０３０の先端側が点火プラグ１０１０の径方向に延在し、浮遊電極１０２６の露出部１０４０が点火プラグ１０１０の軸方向に延在してもよい。この場合は、中心電極１０２２の露出部１０３０の棒先端１０５０は点火プラグ１０１０の径方向外側を向く。 The root side of the exposed portion 1030 of the center electrode 1022 extends in the axial direction of the spark plug 1010, the distal end side of the exposed portion 1030 of the center electrode 1022 extends in the radial direction of the spark plug 1010, and the exposed portion 1040 of the floating electrode 1026 The spark plug 1010 may extend in the axial direction. In this case, the rod tip 1050 of the exposed portion 1030 of the center electrode 1022 faces the radially outer side of the spark plug 1010.

　（碍子の二重構造）
　図３及び図４に示すように、碍子１０２０は、鞘１０９０及び芯１０９２を備える。芯１０９２の外周面には、収容溝１１００が形成される。浮遊電極１０２６の被埋設部１０４２の全体は収容溝１１００に収容され、浮遊電極１０２６は芯１０９２に固定される。浮遊電極１０２６が固定された芯１０９２は、鞘１０９０に収容される。これにより、浮遊電極１０２６の被埋設部１０４２は、碍子１０２０に埋設される。鞘１０９０は、浮遊電極１０２６の被埋設部１０４２と主体金具１０２４とを隔てる。 (Double structure of eggplant)
As shown in FIGS. 3 and 4, the insulator 1020 includes a sheath 1090 and a core 1092. An accommodation groove 1100 is formed on the outer peripheral surface of the core 1092. The entire embedded portion 1042 of the floating electrode 1026 is accommodated in the accommodation groove 1100, and the floating electrode 1026 is fixed to the core 1092. The core 1092 to which the floating electrode 1026 is fixed is accommodated in the sheath 1090. Thereby, the embedded portion 1042 of the floating electrode 1026 is embedded in the insulator 1020. The sheath 1090 separates the embedded portion 1042 of the floating electrode 1026 from the metal shell 1024.

　鞘１０９０と芯１０９２との複合物によれば、浮遊電極１０２６の被埋設部１０４２が埋設された碍子１０２０が容易に製造される。ただし、碍子１０２０が一体物であってもよい。浮遊電極１０２６の被埋設部１０４２の一部を収容する空間が鞘１０９０に形成されてもよい。この場合は、浮遊電極１０２６の被埋設部１０４２の第１の部分が芯１０９２に形成された収容溝に収容され、浮遊電極１０２６の被埋設部１０４２の第２の部分が鞘１０９０に形成された当該空間に収容される。例えば、浮遊電極１０２６の被埋設部１０４２の棒形状部１１２２を収容する収容溝、収容孔等が鞘１０９０に形成され、芯１０９２に形成された収容溝には浮遊電極１０２６の被埋設部１０４２の管形状部１１２０のみが収容されてもよい。 According to the composite of the sheath 1090 and the core 1092, the insulator 1020 in which the embedded portion 1042 of the floating electrode 1026 is embedded is easily manufactured. However, the insulator 1020 may be an integrated object. A space for accommodating a part of the embedded portion 1042 of the floating electrode 1026 may be formed in the sheath 1090. In this case, the first portion of the embedded portion 1042 of the floating electrode 1026 is accommodated in the accommodating groove formed in the core 1092, and the second portion of the embedded portion 1042 of the floating electrode 1026 is formed in the sheath 1090. It is accommodated in the space. For example, a housing groove, a housing hole, or the like that accommodates the rod-shaped portion 1122 of the embedded portion 1042 of the floating electrode 1026 is formed in the sheath 1090, and the housing groove formed in the core 1092 includes the embedded portion 1042 of the floating electrode 1026. Only the tube-shaped portion 1120 may be accommodated.

　（材質）
　碍子１０２０は、セラミックス、樹脂等からなる。セラミックスとしては、アルミナ、ジルコニア等が採用される。樹脂としては、塩化ビニル樹脂、フッ素樹脂等が採用される。 (Material)
The insulator 1020 is made of ceramics, resin, or the like. As the ceramic, alumina, zirconia or the like is employed. As the resin, vinyl chloride resin, fluororesin or the like is employed.

　中心電極１０２２、浮遊電極１０２６及び主体金具１０２４は、導電体からなる。導電体としては、白金等の金属が採用されてもよいし、ステンレス鋼、ニッケル合金等の合金が採用されてもよいし、導電性セラミックスが採用されてもよい。 The center electrode 1022, the floating electrode 1026, and the metal shell 1024 are made of a conductor. As the conductor, a metal such as platinum may be employed, an alloy such as stainless steel or nickel alloy may be employed, or conductive ceramics may be employed.

　（パルス電圧印加機構）
　図１に示すように、パルス電圧印加機構１０１２は、パルス発生回路１２００及びケーブル１２０２を備える。点火プラグ１０１０は、ターミナル１０２８をさらに備える。 (Pulse voltage application mechanism)
As shown in FIG. 1, the pulse voltage application mechanism 1012 includes a pulse generation circuit 1200 and a cable 1202. The spark plug 1010 further includes a terminal 1028.

　ターミナル１０２８とパルス発生回路１２００の正極１２１０とは、ケーブル１２０２により電気的に接続される。主体金具１０２４及びパルス発生回路１２００の負極１２１２は、接地される。 The terminal 1028 and the positive electrode 1210 of the pulse generation circuit 1200 are electrically connected by a cable 1202. The metal shell 1024 and the negative electrode 1212 of the pulse generation circuit 1200 are grounded.

　パルス発生回路１２００が正極１２１０と負極１２１２との間にパルス電圧を発生させた場合は、ターミナル１０２８と主体金具１０２４との間にパルス電圧が印加され、中心電極１０２２と主体金具１０２４との間にパルス電圧が印加される。 When the pulse generation circuit 1200 generates a pulse voltage between the positive electrode 1210 and the negative electrode 1212, a pulse voltage is applied between the terminal 1028 and the metal shell 1024, and between the center electrode 1022 and the metal shell 1024. A pulse voltage is applied.

　ターミナル１０２８が省略され、ケーブル１２０２が中心電極１０２２に直付けされてもよい。ケーブル１２０２が省略され、パルス発生回路１２００の正極１２１０がターミナル１０２８に直付けされてもよい。 The terminal 1028 may be omitted, and the cable 1202 may be directly attached to the center electrode 1022. The cable 1202 may be omitted, and the positive electrode 1210 of the pulse generation circuit 1200 may be directly attached to the terminal 1028.

　パルス発生回路１２００の形式は、望ましくは、誘導エネルギー蓄積型である。ただし、パルス発生回路１２００の形式が誘導エネルギー蓄積型以外であってもよい。 The type of the pulse generation circuit 1200 is preferably an inductive energy storage type. However, the form of the pulse generation circuit 1200 may be other than the induction energy storage type.

　（パルス電圧の波形）
　パルス電圧の波形は、ストリーマ放電は発生するがアーク放電は発生しないように決められる。概ね、ピーク電圧は５～４０ｋＶであり、半値幅は５０～５０００ｎｓであり、繰り返し周波数は５～５００ｋｐｐｓである。放電がストリーマ放電であることは、点火プラグ１０１０に流れる電流の波形により識別される。放電がアーク放電に至った場合は、点火プラグ１０１０に流れる電流が急激に増加するためである。 (Pulse voltage waveform)
The waveform of the pulse voltage is determined so that streamer discharge occurs but arc discharge does not occur. In general, the peak voltage is 5 to 40 kV, the half width is 50 to 5000 ns, and the repetition frequency is 5 to 500 kpps. That the discharge is a streamer discharge is identified by the waveform of the current flowing through the spark plug 1010. This is because the current flowing through the spark plug 1010 increases abruptly when the discharge reaches an arc discharge.

　バースト期間に単パルスを繰り返し印加するバースト信号が中心電極１０２２と主体金具１０２４との間に印加されてもよい。バースト期間は、概ね、０．１～５ｍｓである。 A burst signal that repeatedly applies a single pulse during the burst period may be applied between the center electrode 1022 and the metal shell 1024. The burst period is approximately 0.1 to 5 ms.

　典型的には、パルス電圧は単極性の正パルスであり、中心電極１０２２がアノードになり、主体金具１０２４がカソードになる。ただし、パルス電圧が単極性の負パルスであり、中心電極１０２２がカソードになり、主体金具１０２４がアノードになることも許される。パルス電圧が双極性であってもよい。 Typically, the pulse voltage is a unipolar positive pulse, with the center electrode 1022 serving as the anode and the metal shell 1024 serving as the cathode. However, the pulse voltage is a unipolar negative pulse, the center electrode 1022 can be a cathode, and the metal shell 1024 can be an anode. The pulse voltage may be bipolar.

　（中心電極への給電）
　図３に示すように、碍子１０２０は、被収容部１０８０及び突出部１０８２に加えて、突出部１０８４を備える。突出部１０８４は、丸孔１０６０の外部へ突出し、主体金具１０２４から離れる。突出部１０８４は、点火プラグ１０１０の軸方向後端側に突出し、燃焼容器９０００の外部に露出する。 (Power supply to the center electrode)
As shown in FIG. 3, the insulator 1020 includes a protruding portion 1084 in addition to the accommodated portion 1080 and the protruding portion 1082. The protruding portion 1084 protrudes outside the round hole 1060 and is separated from the metal shell 1024. The protruding portion 1084 protrudes toward the rear end side in the axial direction of the spark plug 1010 and is exposed to the outside of the combustion container 9000.

　碍子１０２０には、軸孔１２２０が形成される。図３においては、軸孔１２２０を他の構成物から識別しやすくするために、中心電極１０２２の一部が破断線により便宜的に消去されている。軸孔１２２０は、突出部１０８２から被収容部１０８０を経由して突出部１０８４へ至る。 A shaft hole 1220 is formed in the insulator 1020. In FIG. 3, a part of the center electrode 1022 is conveniently removed by a broken line so that the shaft hole 1220 can be easily distinguished from other components. The shaft hole 1220 extends from the protruding portion 1082 to the protruding portion 1084 via the accommodated portion 1080.

　中心電極１０２２は、棒形状を有する。中心電極１０２２は、露出部１０３０及び被埋設部１０３２に加えて、露出部１０３４を備える。中心電極１０２２の露出部１０３４は、軸孔１２２０の外部に突出する。中心電極１０２２の露出部１０３４は、点火プラグ１０１０の軸方向後端側へ突出する。中心電極１０２２の露出部１０３４には、ターミナル１０２８が螺合される。これにより、ターミナル１０２８が主体金具１０２４から離れ、中心電極１０２２への給電が容易になる。中心電極１０２２は、ターミナル１０２８の螺合により碍子１０２０に固定される。 The center electrode 1022 has a rod shape. The center electrode 1022 includes an exposed portion 1034 in addition to the exposed portion 1030 and the embedded portion 1032. The exposed portion 1034 of the center electrode 1022 protrudes outside the shaft hole 1220. The exposed portion 1034 of the center electrode 1022 protrudes toward the rear end side in the axial direction of the spark plug 1010. A terminal 1028 is screwed into the exposed portion 1034 of the center electrode 1022. Thereby, the terminal 1028 is separated from the metal shell 1024, and power feeding to the center electrode 1022 is facilitated. Center electrode 1022 is fixed to insulator 1020 by screwing terminal 1028.

　（混合気の漏れの抑制）
　図３に示すように、点火プラグ１０１０は、ガスケットワッシャー１２３０及び１２３２をさらに備える。ガスケットワッシャー１２３０及び１２３２は、丸孔１０６０の内部において碍子１０２０と主体金具１０２４との間隙に挟まれる。これにより、碍子１０２０と主体金具１０２４との間隙から混合気が漏れにくくなる。 (Suppression of air-fuel mixture leakage)
As shown in FIG. 3, the spark plug 1010 further includes gasket washers 1230 and 1232. The gasket washers 1230 and 1232 are sandwiched between the insulator 1020 and the metal shell 1024 inside the round hole 1060. Thereby, the air-fuel mixture is less likely to leak from the gap between the insulator 1020 and the metal shell 1024.

　（点火の手順）
　点火プラグ１０１０及び燃焼容器９０００が準備され、点火プラグ１０１０が燃焼容器９０００に取り付けられる。燃焼容器９０００が省略され、開放された燃焼空間に満たされた混合気への点火に点火プラグ１０１０が用いられてもよい。 (Ignition procedure)
A spark plug 1010 and a combustion container 9000 are prepared, and the spark plug 1010 is attached to the combustion container 9000. The combustion container 9000 may be omitted, and the spark plug 1010 may be used to ignite the air-fuel mixture filled in the opened combustion space.

　点火プラグ１０１０が燃焼容器９０００に取り付けられた後に、ターミナル１０２８と主体金具１０２４との間にパルス電圧が印加され、中心電極１０２２と主体金具１０２４との間にパルス電圧が印加される。これにより、中心電極１０２２の露出部１０３０と浮遊電極１０２６の露出部１０４０との間に強力なストリーマ放電が発生し、混合気が点火される。 After the ignition plug 1010 is attached to the combustion container 9000, a pulse voltage is applied between the terminal 1028 and the metal shell 1024, and a pulse voltage is applied between the center electrode 1022 and the metal shell 1024. As a result, a strong streamer discharge is generated between the exposed portion 1030 of the center electrode 1022 and the exposed portion 1040 of the floating electrode 1026, and the air-fuel mixture is ignited.

　（用途）
　点火装置１０００は、主に、エンジンの燃焼室に満たされた混合気への点火に用いられる。ただし、点火装置１０００が他の用途に用いられてもよい。エンジンは、望ましくは内燃機関であり、さらに望ましくはレシプロエンジンである。レシプロエンジンは、４サイクルエンジン及び２サイクルエンジンのいずれであってもよい。ただし、エンジンが外燃機関であってもよい。また、エンジンがレシプロエンジン以外の内燃機関であってもよい。例えば、エンジンがロータリーエンジンであってもよい。エンジンがガスエンジンであってもよい。 (Use)
The ignition device 1000 is mainly used for igniting an air-fuel mixture filled in a combustion chamber of an engine. However, the ignition device 1000 may be used for other purposes. The engine is preferably an internal combustion engine, and more preferably a reciprocating engine. The reciprocating engine may be either a 4-cycle engine or a 2-cycle engine. However, the engine may be an external combustion engine. The engine may be an internal combustion engine other than a reciprocating engine. For example, the engine may be a rotary engine. The engine may be a gas engine.

　エンジンは、典型的には、自動車に組み込まれる。ただし、エンジンが自動車以外の輸送機械に組み込まれてもよい。例えば、エンジンが鉄道車両、産業車両、船舶、航空機、宇宙船等に組み込まれてもよい。エンジンが輸送機械以外の機械に組み込まれてもよい。例えば、エンジンが工具、農具、発動発電機等に組み込まれてもよい。 The engine is typically built into a car. However, the engine may be incorporated in a transport machine other than an automobile. For example, the engine may be incorporated in a railway vehicle, an industrial vehicle, a ship, an aircraft, a spacecraft, or the like. The engine may be incorporated in a machine other than the transport machine. For example, the engine may be incorporated in a tool, a farm tool, an engine generator, or the like.

　（混合気）
　混合気は、空気と燃料油との混合物である。混合気が空気と可燃性気体との混合物であってもよい。例えば、混合気が空気と水素ガス、プロパンガス、ブタンガス等との混合物であってもよい。可燃性気体が混合物であってもよい。 (Mixture)
The air-fuel mixture is a mixture of air and fuel oil. The air-fuel mixture may be a mixture of air and combustible gas. For example, the air-fuel mixture may be a mixture of air and hydrogen gas, propane gas, butane gas, or the like. The combustible gas may be a mixture.

　空気が他の種類の支燃性気体に置き換えられてもよい。例えば、空気が酸素に置き換えられてもよい。燃料油が他の種類の可燃性液体に置き換えられてもよい。例えば、燃料油がメタノールに置き換えられてもよい。 ∙ Air may be replaced with other types of flammable gases. For example, air may be replaced with oxygen. The fuel oil may be replaced with other types of flammable liquids. For example, the fuel oil may be replaced with methanol.

　混合気の圧力は、典型的には大気圧であるが、減圧又は加圧されてもよい。 The pressure of the air-fuel mixture is typically atmospheric pressure, but may be reduced or increased.

　｛第２実施形態｝
　（概略）
　第２実施形態は、第１実施形態の点火プラグを置き換える点火プラグに関する。以下では、第１実施形態の点火プラグと第２実施形態の点火プラグとの重要な共通点及び相違点が説明される。説明されない事項については、第１実施形態又はその他の実施形態の点火プラグの構成が、そのまま又は変形されてから、第２実施形態の点火プラグにおいて採用される。第２実施形態の点火プラグの構成物には、第１実施形態の点火プラグの対応する構成物と同じ名称が付与される。 {Second Embodiment}
(Outline)
The second embodiment relates to a spark plug that replaces the spark plug of the first embodiment. Hereinafter, important common points and differences between the spark plug of the first embodiment and the spark plug of the second embodiment will be described. About the matter which is not demonstrated, after the structure of the spark plug of 1st Embodiment or another embodiment is changed or changed, it is employ | adopted in the spark plug of 2nd Embodiment. The components of the spark plug of the second embodiment are given the same names as the corresponding components of the spark plug of the first embodiment.

　図１０の模式図は、第２実施形態の点火プラグの斜視図である。図１１の模式図は、第２実施形態の点火プラグの断面図である。図１２の模式図は、第２実施形態の碍子の分解斜視図である。図１３の模式図は、第２実施形態の浮遊電極の斜視図である。 10 is a perspective view of a spark plug according to the second embodiment. The schematic diagram of FIG. 11 is sectional drawing of the ignition plug of 2nd Embodiment. The schematic diagram of FIG. 12 is an exploded perspective view of the insulator of the second embodiment. The schematic diagram of FIG. 13 is a perspective view of the floating electrode of the second embodiment.

　図１０及び図１１に示すように、点火プラグ２０１０は、第１実施形態と同じく、碍子２０２０、中心電極２０２２、主体金具２０２４及び浮遊電極２０２６を備える。中心電極２０２２は、露出部２０３０及び被埋設部２０３２を備える。浮遊電極２０２６は、露出部２０４０及び被埋設部２０４２を備える。 As shown in FIGS. 10 and 11, the spark plug 2010 includes an insulator 2020, a center electrode 2022, a metal shell 2024, and a floating electrode 2026, as in the first embodiment. The center electrode 2022 includes an exposed portion 2030 and an embedded portion 2032. The floating electrode 2026 includes an exposed portion 2040 and an embedded portion 2042.

　第１実施形態と同じく、浮遊電極２０２６の露出部２０４０は中心電極２０２２の露出部２０３０に相対的に近く、主体金具２０２４は中心電極２０２２の露出部２０３０から相対的に遠い。中心電極２０２２と浮遊電極２０２６との間の静電容量Ｃ１は相対的に小さく、浮遊電極２０２６と主体金具２０２４との間の静電容量Ｃ２は相対的に大きい。したがって、中心電極２０２２と主体金具２０２４との間にパルス電圧が印加された場合は、中心電極２０２２と浮遊電極２０２６との間に高圧が誘起され、中心電極２０２２の露出部２０３０と浮遊電極２０２６の露出部２０４０との間に強力なストリーマ放電が発生する。この強力なストリーマ放電により、混合気が点火される。放電体積が大きくなり難燃焼条件であっても混合気に安定して点火できることは、第１実施形態と同じである。点火プラグ２０１０に流れる電流が減少し単位放電体積あたりの消費エネルギーが減少することも、第１実施形態と同じである。 As in the first embodiment, the exposed portion 2040 of the floating electrode 2026 is relatively close to the exposed portion 2030 of the center electrode 2022, and the metal shell 2024 is relatively far from the exposed portion 2030 of the center electrode 2022. The electrostatic capacitance C1 between the center electrode 2022 and the floating electrode 2026 is relatively small, and the electrostatic capacitance C2 between the floating electrode 2026 and the metal shell 2024 is relatively large. Therefore, when a pulse voltage is applied between the center electrode 2022 and the metal shell 2024, a high voltage is induced between the center electrode 2022 and the floating electrode 2026, and the exposed portion 2030 of the center electrode 2022 and the floating electrode 2026 A powerful streamer discharge is generated between the exposed portion 2040 and the exposed portion 2040. This powerful streamer discharge ignites the air-fuel mixture. It is the same as in the first embodiment that the air-fuel mixture can be ignited stably even when the discharge volume is large and the combustion is difficult. It is the same as in the first embodiment that the current flowing through the spark plug 2010 decreases and the energy consumption per unit discharge volume decreases.

　（中心電極の中空保持構造）
　図１１に示すように、碍子２０２０には、軸孔２２２０が形成される。軸孔２２２０は、碍子２０２０の内部の中空空間になる。 (Hollow holding structure of center electrode)
As shown in FIG. 11, a shaft hole 2220 is formed in the insulator 2020. The shaft hole 2220 becomes a hollow space inside the insulator 2020.

　中心電極２０２２の被埋設部２０３２は、軸孔２２２０に収容される。 The embedded portion 2032 of the center electrode 2022 is accommodated in the shaft hole 2220.

　第１実施形態と異なり、中心電極２０２２の被埋設部２０３２は、被中空保持部２２６０を備える。被中空保持部２２６０は、軸孔２２２０の内部に中空保持される。被中空保持部２２６０と碍子２０２０との間には、空隙２２５０が形成される。これにより、碍子２０２０の内部で中心電極２０２２が空隙２２５０に囲まれ、中心電極２０２２と浮遊電極２０２６との間の静電容量Ｃ１が小さくなる。 Unlike the first embodiment, the embedded portion 2032 of the center electrode 2022 includes a hollow holding portion 2260. The hollow holding portion 2260 is held hollow inside the shaft hole 2220. A gap 2250 is formed between the hollow holding portion 2260 and the insulator 2020. As a result, the center electrode 2022 is surrounded by the gap 2250 inside the insulator 2020, and the capacitance C1 between the center electrode 2022 and the floating electrode 2026 is reduced.

　被中空保持部２２６０は、中心電極２０２２の被埋設部２０３２の主要部を占める。中心電極２０２２の被埋設部２０３２に占める被中空保持部２２６０の比率が増減されてもよい。 The hollow holding part 2260 occupies the main part of the buried part 2032 of the center electrode 2022. The ratio of the hollow holding portion 2260 occupying the buried portion 2032 of the center electrode 2022 may be increased or decreased.

　図１１及び図１３に示すように、浮遊電極２０２６の被埋設部２０４２は、管形状部２１２０を備える。中心電極２０２２の被埋設部２０３２は、管形状部２１２０の管内を通過する。中心電極２０２２の被埋設部２０３２のうち中心電極２０２２と浮遊電極２０２６との間の静電容量Ｃ１の増加に主に寄与するのは、管形状部２１２０の管内を通過する部分である。このため、中心電極２０２２の被埋設部２０３２に占める被中空保持部２２６０の比率が減らされる場合であっても、管形状部２１２０の管内を通過する部分は被中空保持部２２６０にされる。 As shown in FIGS. 11 and 13, the embedded portion 2042 of the floating electrode 2026 includes a tube-shaped portion 2120. The embedded portion 2032 of the center electrode 2022 passes through the inside of the tube-shaped portion 2120. The portion of the embedded portion 2032 of the center electrode 2022 that mainly contributes to the increase in the capacitance C1 between the center electrode 2022 and the floating electrode 2026 is a portion that passes through the tube of the tube-shaped portion 2120. For this reason, even if the ratio of the hollow holding portion 2260 occupying the buried portion 2032 of the center electrode 2022 is reduced, the portion of the tube-shaped portion 2120 that passes through the tube is made the hollow holding portion 2260.

　軸孔２２２０が、「軸孔」とは呼びがたい形状を有する中空空間に置き換えられてもよい。 The shaft hole 2220 may be replaced with a hollow space having a shape difficult to call a “shaft hole”.

　図１１及び図１２に示すように、碍子２０２０は、鞘２０９０及び芯２０９２を備える。軸孔２２２０の断面形状は、芯２０９２の軸方向後端側及び鞘２０９０においては中心電極２０２２の被埋設部２０３２の断面形状とほぼ同じであり、芯２０９２の軸方向先端側においては中心電極２０２２の被埋設部２０３２の断面形状より大きい。これにより、芯２０９２の軸方向後端側及び鞘２０９０において点火プラグ２０１０の径方向への中心電極２０２２の移動が規制される。このため、中心電極２０２２が固定され、被中空保持部２２６０が軸孔２２２０の内部に中空保持される。 As shown in FIGS. 11 and 12, the insulator 2020 includes a sheath 2090 and a core 2092. The cross-sectional shape of the axial hole 2220 is substantially the same as the cross-sectional shape of the embedded portion 2032 of the center electrode 2022 on the rear end side in the axial direction of the core 2092 and the sheath 2090, and on the front end side in the axial direction of the core 2092. It is larger than the cross-sectional shape of the embedded portion 2032. Thereby, the movement of the center electrode 2022 in the radial direction of the spark plug 2010 is restricted at the axial rear end side of the core 2092 and the sheath 2090. For this reason, the center electrode 2022 is fixed, and the hollow holding portion 2260 is held hollow inside the shaft hole 2220.

　（碍子の二重構造）
　図１１及び図１２に示すように、碍子２０２０は、鞘２０９０及び芯２０９２を備える。鞘２０９０には、収容孔２２６０が形成される。芯２０９２は、保持軸２２７０を備える。図１３に示すように、浮遊電極２０２６は、管形状部２１２０から棒体２８０２が伸びる構造を有する。浮遊電極２０２６の被埋設部２０４２は、管形状部２１２０及び棒形状部２１２２を備える。管形状部２１２０には保持軸２２７０が差し込まれ、浮遊電極２０２６は芯２０９２に固定される。浮遊電極２０２６が固定された芯２０９２は、鞘２０９０に収容される。このとき、棒形状部２１２２は、収容孔２２６０に収容される。これにより、浮遊電極２０６６の被埋設部２０４２は、碍子２０２０に埋設される。 (Double structure of eggplant)
As shown in FIGS. 11 and 12, the insulator 2020 includes a sheath 2090 and a core 2092. A housing hole 2260 is formed in the sheath 2090. The core 2092 includes a holding shaft 2270. As shown in FIG. 13, the floating electrode 2026 has a structure in which a rod body 2802 extends from the tubular portion 2120. The embedded portion 2042 of the floating electrode 2026 includes a tube-shaped portion 2120 and a rod-shaped portion 2122. A holding shaft 2270 is inserted into the tube-shaped portion 2120, and the floating electrode 2026 is fixed to the core 2092. The core 2092 to which the floating electrode 2026 is fixed is accommodated in the sheath 2090. At this time, the bar-shaped portion 2122 is accommodated in the accommodation hole 2260. Thereby, the embedded portion 2042 of the floating electrode 2066 is embedded in the insulator 2020.

　（浮遊電極の露出部の数）
　図１１及び図１３に示すように、浮遊電極２０２６は、第１実施形態と異なり、２個の露出部２０４０を備える。これにより、放電体積が大きくなる。浮遊電極２０２６の露出部２０４０の数が増減されてもよい。浮遊電極２０２６の露出部２０４０は、中心電極２０２２の露出部２０３２の周りに回転対称に配置される。これにより、放電が均一に発生し、放電体積が大きくなる。 (Number of exposed parts of floating electrode)
As shown in FIGS. 11 and 13, the floating electrode 2026 includes two exposed portions 2040 unlike the first embodiment. This increases the discharge volume. The number of exposed portions 2040 of the floating electrode 2026 may be increased or decreased. The exposed portion 2040 of the floating electrode 2026 is disposed rotationally symmetrically around the exposed portion 2032 of the center electrode 2022. As a result, the discharge is uniformly generated and the discharge volume is increased.

　（中心電極）
　図１０及び図１１に示すように、中心電極２０２２の露出部２０３０は、棒先端２０５０を有する。第１実施形態と同じく、棒先端２０５０の数は１個であり、棒先端２０５０は平面である。第１実施形態と同じく、中心電極２０２２はターミナル２０２８の螺合により碍子２０２０に固定される。 (Center electrode)
As shown in FIGS. 10 and 11, the exposed portion 2030 of the center electrode 2022 has a rod tip 2050. As in the first embodiment, the number of rod tips 2050 is one, and the rod tips 2050 are flat. As in the first embodiment, the center electrode 2022 is fixed to the insulator 2020 by screwing the terminal 2028.

　｛第３実施形態｝
　（概略）
　第３実施形態は、第１実施形態の点火プラグを置き換える点火プラグに関する。以下では、第１実施形態の点火プラグと第３実施形態の点火プラグとの重要な共通点及び相違点が説明される。説明されない事項については、第１実施形態又はその他の実施形態の点火プラグの構成が、そのまま又は変形されてから、第３実施形態の点火プラグにおいて採用される。第３実施形態の点火プラグの構成物には、第１実施形態の点火プラグの対応する構成物と同じ名称が付与される。 {Third embodiment}
(Outline)
The third embodiment relates to a spark plug that replaces the spark plug of the first embodiment. In the following, important common points and differences between the spark plug of the first embodiment and the spark plug of the third embodiment will be described. About the matter which is not demonstrated, the structure of the spark plug of 1st Embodiment or another embodiment is employ | adopted in the spark plug of 3rd Embodiment as it is or after changing. The components of the spark plug of the third embodiment are given the same names as the corresponding components of the spark plug of the first embodiment.

　図１４の模式図は、第３実施形態の点火プラグの斜視図である。図１５の模式図は、第３実施形態の点火プラグの断面図である。 14 is a perspective view of the spark plug of the third embodiment. The schematic diagram of FIG. 15 is sectional drawing of the ignition plug of 3rd Embodiment.

　図１４及び図１５に示すように、点火プラグ３０１０は、第１実施形態と同じく、碍子３０２０、中心電極３０２２、主体金具３０２４及び浮遊電極３０２６を備える。中心電極３０２２は、露出部３０３０及び被埋設部３０３２を備える。浮遊電極３０２６は、露出部３０４０及び被埋設部３０４２を備える。 As shown in FIGS. 14 and 15, the spark plug 3010 includes an insulator 3020, a center electrode 3022, a metal shell 3024, and a floating electrode 3026, as in the first embodiment. The center electrode 3022 includes an exposed portion 3030 and an embedded portion 3032. The floating electrode 3026 includes an exposed portion 3040 and an embedded portion 3042.

　第１実施形態と同じく、浮遊電極３０２６の露出部３０４０は中心電極３０２２の露出部３０３０に相対的に近く、主体金具３０２４は中心電極３０２２の露出部３０３０から相対的に遠い。中心電極３０２２と浮遊電極３０２６との間の静電容量Ｃ１は相対的に小さく、浮遊電極３０２６と主体金具３０２４との間の静電容量Ｃ２は相対的に大きい。したがって、中心電極３０２２と主体金具３０２４との間にパルス電圧が印加された場合は、中心電極３０２２と浮遊電極３０２６との間に高圧が誘起され、中心電極３０２２の露出部３０３０と浮遊電極３０２６の露出部３０４０との間に強力なストリーマ放電が発生する。この強力なストリーマ放電により、混合気が点火される。放電体積が大きくなり難燃焼条件であっても混合気に安定して点火できることは、第１実施形態と同じである。点火プラグ３０１０に流れる電流が減少し単位放電体積あたりの消費エネルギーが減少することも、第１実施形態と同じである。 As in the first embodiment, the exposed portion 3040 of the floating electrode 3026 is relatively close to the exposed portion 3030 of the center electrode 3022, and the metal shell 3024 is relatively far from the exposed portion 3030 of the center electrode 3022. The capacitance C1 between the center electrode 3022 and the floating electrode 3026 is relatively small, and the capacitance C2 between the floating electrode 3026 and the metal shell 3024 is relatively large. Therefore, when a pulse voltage is applied between the center electrode 3022 and the metal shell 3024, a high voltage is induced between the center electrode 3022 and the floating electrode 3026, and the exposed portion 3030 of the center electrode 3022 and the floating electrode 3026 A powerful streamer discharge is generated between the exposed portion 3040 and the exposed portion 3040. This powerful streamer discharge ignites the air-fuel mixture. It is the same as in the first embodiment that the air-fuel mixture can be ignited stably even when the discharge volume is large and the combustion is difficult. It is the same as in the first embodiment that the current flowing through the spark plug 3010 decreases and the energy consumption per unit discharge volume decreases.

　（浮遊電極の数）
　第１実施形態と異なり、点火プラグ３０１０は、４個の浮遊電極３０２６を備える。浮遊電極３０２６の数が増減されてもよい。より一般的には、２個以上の浮遊電極３０２６が設けられる。 (Number of floating electrodes)
Unlike the first embodiment, the spark plug 3010 includes four floating electrodes 3026. The number of floating electrodes 3026 may be increased or decreased. More generally, two or more floating electrodes 3026 are provided.

　４個の浮遊電極３０２６は、互いに絶縁される。これにより、４個の浮遊電極３０２６の電位が独立する。このため、中心電極３０２２の露出部３０３０と一の浮遊電極３０２６の露出部３０４０との間に放電が発生しても、中心電極３０２２の露出部３０３０と他の浮遊電極３０２６の露出部３０４０との間の放電が妨げられず、多点放電が発生しやすくなり、放電体積が大きくなる。多点放電を構成する各々の放電は、強力なストリーマ放電であるため、それ自身で混合気に点火する能力を有する。多点放電においては、同時に２個以上の放電が異なる場所で発生する。ただし、２個以上の放電のタイミングがわずかにずれてもよい。 The four floating electrodes 3026 are insulated from each other. Thereby, the potentials of the four floating electrodes 3026 are independent. For this reason, even if discharge occurs between the exposed portion 3030 of the center electrode 3022 and the exposed portion 3040 of one floating electrode 3026, the exposed portion 3030 of the central electrode 3022 and the exposed portion 3040 of the other floating electrode 3026 Discharge is not hindered, multi-point discharge is likely to occur, and the discharge volume increases. Since each discharge constituting the multipoint discharge is a powerful streamer discharge, it has the ability to ignite the air-fuel mixture by itself. In multi-point discharge, two or more discharges occur simultaneously at different locations. However, the timing of two or more discharges may be slightly shifted.

　（電極の位置の関係）
　図１６の模式図は、第３実施形態の電極の位置の関係を示す。 (Relationship of electrode position)
The schematic diagram of FIG. 16 shows the positional relationship of the electrode of 3rd Embodiment.

　図１６に示すように、浮遊電極３０２６の露出部３０４０は中心電極３０２２の露出部３０３０に相対的に近づけられ、主体金具３０２４は中心電極３０２２の露出部３０３０から相対的に遠ざけられる。したがって、浮遊電極３０２６の露出部３０４０から燃焼室９００２を経由して中心電極３０２２の露出部３０３０までの放電経路長Ｌ１は相対的に短く、主体金具３０２４から燃焼室９００２を経由して中心電極３０２２の露出部３０３０までの放電経路長Ｌ２は相対的に長く、Ｌ１＜Ｌ２が成立する。中心電極３０２２の露出部３０３０と浮遊電極３０２６の露出部３０４０との放電ギャップは、中心電極３０２２の露出部３０３０と主体金具３０２４との放電ギャップより狭い。４個の浮遊電極３０２６の各々について放電経路長Ｌ１は均一である。これにより、中心電極３０２２の露出部３０３０と特定の浮遊電極３０２６の露出部３０４０との間に放電が偏らず、多点放電が発生しやすくなる。ただし、放電経路長Ｌ１にわずかなバラツキがあってもよい。 16, the exposed portion 3040 of the floating electrode 3026 is relatively close to the exposed portion 3030 of the center electrode 3022, and the metal shell 3024 is relatively away from the exposed portion 3030 of the center electrode 3022. Therefore, the discharge path length L1 from the exposed portion 3040 of the floating electrode 3026 to the exposed portion 3030 of the center electrode 3022 via the combustion chamber 9002 is relatively short, and the center electrode 3022 passes from the metal shell 3024 via the combustion chamber 9002. The discharge path length L2 to the exposed portion 3030 is relatively long, and L1 <L2 is established. The discharge gap between the exposed portion 3030 of the center electrode 3022 and the exposed portion 3040 of the floating electrode 3026 is narrower than the discharge gap between the exposed portion 3030 of the center electrode 3022 and the metal shell 3024. The discharge path length L1 is uniform for each of the four floating electrodes 3026. As a result, the discharge is not biased between the exposed portion 3030 of the center electrode 3022 and the exposed portion 3040 of the specific floating electrode 3026, and multipoint discharge is likely to occur. However, there may be slight variations in the discharge path length L1.

　（静電容量の関係）
　図１７の回路図は、第３実施形態の点火プラグの等価回路を示す。 (Capacitance relationship)
The circuit diagram of FIG. 17 shows an equivalent circuit of the spark plug of the third embodiment.

　図１７に示すように、中心電極３０２２と主体金具３０２４との間に電圧Ｖが印加された場合には、中心電極３０２２と浮遊電極３０２６との間の電圧Ｖ１及び浮遊電極３０２６と主体金具３０２４との間の電圧Ｖ２に電圧Ｖが分圧され、Ｖ＝Ｖ１＋Ｖ２が成立する。４個の浮遊電極３０２６は互いに絶縁されるので、一の浮遊電極３０２６から他の浮遊電極３０２６へは直接的には電流が流れない。４個の浮遊電極３０２６の各々について、中心電極３０２２と浮遊電極３０２６との間の静電容量Ｃ１は均一であり、浮遊電極３０２６と主体金具３０２４との間の静電容量Ｃ２は均一である。これにより、中心電極３０２２の露出部３０３０と特定の浮遊電極３０２６の露出部３０４０との間に放電が偏らず、多点放電が発生しやすくなる。ただし、静電容量Ｃ１にわずかなバラツキがあってもよく、静電容量Ｃ２にわずかなバラツキがあってもよい。 As shown in FIG. 17, when the voltage V is applied between the center electrode 3022 and the metal shell 3024, the voltage V1 between the center electrode 3022 and the floating electrode 3026 and the floating electrode 3026 and the metal shell 3024 The voltage V is divided into the voltage V2 between the two, and V = V1 + V2 is established. Since the four floating electrodes 3026 are insulated from each other, no current flows directly from one floating electrode 3026 to the other floating electrode 3026. For each of the four floating electrodes 3026, the capacitance C1 between the center electrode 3022 and the floating electrode 3026 is uniform, and the capacitance C2 between the floating electrode 3026 and the metal shell 3024 is uniform. As a result, the discharge is not biased between the exposed portion 3030 of the center electrode 3022 and the exposed portion 3040 of the specific floating electrode 3026, and multipoint discharge is likely to occur. However, the electrostatic capacitance C1 may have slight variations, and the electrostatic capacitance C2 may have slight variations.

　（一体物の碍子）
　図１５に示すように、碍子３０２０は、第１実施形態と異なり、一体物である。これにより、碍子３０２０の機械的強度が向上し、混合気の漏れが抑制される。 (One-piece lion)
As shown in FIG. 15, the insulator 3020 is an integral object unlike the first embodiment. Thereby, the mechanical strength of the insulator 3020 is improved and leakage of the air-fuel mixture is suppressed.

　（浮遊電極）
　図１５に示すように、碍子３０２０は、第１実施形態と同じく、被収容部３０８０及び突出部３０８２を備える。主体金具３０２４には、丸孔３０６０が形成される。図１５においては、丸孔３０６０を他の構成物から識別しやすくするために、碍子３０２０の一部が破断線により便宜的に消去されている。被収容部３０８０は、丸孔３０６０の内部に収容される。突出部３０８２は、丸孔３０６０の外部に突出する。突出部３０８２は、点火プラグ３０１０の軸方向先端側に突出し、燃焼空間９００２に露出する。 (Floating electrode)
As shown in FIG. 15, the insulator 3020 includes a accommodated portion 3080 and a protruding portion 3082 as in the first embodiment. A round hole 3060 is formed in the metal shell 3024. In FIG. 15, in order to make it easy to identify the round hole 3060 from other components, a part of the insulator 3020 is conveniently deleted by a broken line. The accommodated portion 3080 is accommodated inside the round hole 3060. The protruding portion 3082 protrudes outside the round hole 3060. The protruding portion 3082 protrudes toward the tip end side in the axial direction of the spark plug 3010 and is exposed to the combustion space 9002.

　図１４及び図１５に示すように、突出部３０８２の先端面３２９０には、第１実施形態と異なり、中心溝３３００及び４個の放射状溝３３０２が形成される。中心溝３３００は相対的に深く、４個の放射状溝３３０２は相対的に浅い。４個の放射状溝３３０２は、中心溝３３００から放射状に伸びる。中心溝３３００には、中心電極３０２２の露出部３０３０が収容される。４個の放射状溝３３０２の各々には、浮遊電極３０２６の露出部３０４０が１個ずつ収容される。これにより、隣接する浮遊電極３０２６の露出部３０４０が碍子３０２０で隔てられ、隣接する浮遊電極３０２６の露出部３０４０の間に放電が発生しにくくなる。また、中心電極３０２２の露出部３０３０と浮遊電極３０２６の露出部３０４０とが碍子３０２０で隔てられず、中心電極３０２２の露出部３０３０と浮遊電極３０２６の露出部３０４０との間に放電が発生しやすくなる。 As shown in FIGS. 14 and 15, unlike the first embodiment, a central groove 3300 and four radial grooves 3302 are formed on the distal end surface 3290 of the protrusion 3082. The central groove 3300 is relatively deep and the four radial grooves 3302 are relatively shallow. Four radial grooves 3302 extend radially from the central groove 3300. The exposed portion 3030 of the center electrode 3022 is accommodated in the center groove 3300. One exposed portion 3040 of the floating electrode 3026 is accommodated in each of the four radial grooves 3302. As a result, the exposed portion 3040 of the adjacent floating electrode 3026 is separated by the insulator 3020, and the discharge is less likely to occur between the exposed portions 3040 of the adjacent floating electrode 3026. Further, the exposed portion 3030 of the center electrode 3022 and the exposed portion 3040 of the floating electrode 3026 are not separated by the insulator 3020, and a discharge is easily generated between the exposed portion 3030 of the center electrode 3022 and the exposed portion 3040 of the floating electrode 3026. Become.

　４個の放射状溝３３０２の底には、孔３３１０が形成される。図１５においては、孔３３１０を他の構成物から識別しやすくするために、浮遊電極３０２６の一部が破断線により便宜的に消去されている。孔３３１０は、点火プラグ３０１０の軸方向に延在する。孔３３１０の内周面及び放射状溝３３０２の底には、メッキにより導電体膜が形成される。当該導電体膜は、浮遊電極３０２６になる。孔３３１０の内周面及び放射状溝３３０２の底に、導電ペーストが焼きつけられてもよい。孔３３１０及び放射状溝３３０２に導電体が充填されてもよい。これにより、一体物の碍子３０２０に被埋設部３０４２が埋設された浮遊電極３０２６が容易に作製される。 A hole 3310 is formed at the bottom of the four radial grooves 3302. In FIG. 15, a part of the floating electrode 3026 is conveniently deleted by a broken line in order to make the hole 3310 easily distinguishable from other components. The hole 3310 extends in the axial direction of the spark plug 3010. A conductor film is formed on the inner peripheral surface of the hole 3310 and the bottom of the radial groove 3302 by plating. The conductor film becomes the floating electrode 3026. A conductive paste may be baked on the inner peripheral surface of the hole 3310 and the bottom of the radial groove 3302. The holes 3310 and the radial grooves 3302 may be filled with a conductor. Thereby, the floating electrode 3026 in which the embedded portion 3042 is embedded in the integrated insulator 3020 is easily manufactured.

　（中心電極の中空保持）
　図１５に示すように、中心電極３０２２の被埋設部３０３２の被中空保持部３２６０は、第２実施形態と同じく、碍子３０２０に形成された軸孔３２２０の内部に中空保持される。これにより、碍子３０２０の内部で中心電極３０２２が空隙３２５０に囲まれ、中心電極３０２２と浮遊電極３０２６との間の静電容量Ｃ１が小さくなる。 (Holding the center electrode hollow)
As shown in FIG. 15, the hollow holding portion 3260 of the buried portion 3032 of the center electrode 3022 is hollowly held inside a shaft hole 3220 formed in the insulator 3020 as in the second embodiment. As a result, the center electrode 3022 is surrounded by the gap 3250 inside the insulator 3020, and the capacitance C1 between the center electrode 3022 and the floating electrode 3026 is reduced.

　｛第４実施形態｝
　（概略）
　第４実施形態は、第１実施形態の点火プラグを置き換える点火プラグに関する。以下では、第１実施形態の点火プラグと第４実施形態の点火プラグとの重要な共通点及び相違点が説明される。説明されない事項については、第１実施形態又はその他の実施形態の点火プラグの構成が、そのまま又は変形されてから、第４実施形態の点火プラグにおいて採用される。第４実施形態の点火プラグの構成物には、第１実施形態の点火プラグの対応する構成物と同じ名称が付与される。 {Fourth embodiment}
(Outline)
The fourth embodiment relates to a spark plug that replaces the spark plug of the first embodiment. In the following, important common points and differences between the spark plug of the first embodiment and the spark plug of the fourth embodiment will be described. About the matter which is not demonstrated, after the structure of the spark plug of 1st Embodiment or another embodiment is changed or changed, it is employ | adopted in the spark plug of 4th Embodiment. The components of the spark plug of the fourth embodiment are given the same names as the corresponding components of the spark plug of the first embodiment.

　図１８の模式図は、第４実施形態の点火プラグの斜視図である。図１９の模式図は、第４実施形態の点火プラグの断面図である。図２０の模式図は、第４実施形態の碍子の分解斜視図である。図２１の模式図は、第４実施形態の浮遊電極の斜視図である。 18 is a perspective view of the spark plug of the fourth embodiment. The schematic diagram of FIG. 19 is sectional drawing of the ignition plug of 4th Embodiment. The schematic diagram of FIG. 20 is an exploded perspective view of the insulator of the fourth embodiment. The schematic diagram of FIG. 21 is a perspective view of the floating electrode of 4th Embodiment.

　図１８及び図１９に示すように、点火プラグ４０１０は、第１実施形態と同じく、碍子４０２０、中心電極４０２２、主体金具４０２４及び浮遊電極４０２６を備える。中心電極４０２２は、露出部４０３０及び被埋設部４０３２を備える。浮遊電極４０２６は、露出部４０４０及び被埋設部４０４２を備える。 As shown in FIGS. 18 and 19, the spark plug 4010 includes an insulator 4020, a center electrode 4022, a metal shell 4024, and a floating electrode 4026, as in the first embodiment. The center electrode 4022 includes an exposed portion 4030 and an embedded portion 4032. The floating electrode 4026 includes an exposed portion 4040 and an embedded portion 4042.

　第１実施形態と同じく、浮遊電極４０２６の露出部４０４０は中心電極４０２２の露出部４０３０に相対的に近く、主体金具４０２４は中心電極４０２２の露出部４０３０から相対的に遠い。中心電極４０２２と浮遊電極４０２６との間の静電容量Ｃ１は相対的に小さく、浮遊電極４０２６と主体金具４０２４との間の静電容量Ｃ２は相対的に大きい。したがって、中心電極４０２２と主体金具４０２４との間にパルス電圧が印加された場合は、中心電極４０２２と浮遊電極４０２６との間に高圧が誘起され、中心電極４０２２の露出部４０３０と浮遊電極４０２６の露出部４０４０との間に強力なストリーマ放電が発生する。この強力なストリーマ放電により、混合気が点火される。放電体積が大きくなり難燃焼条件であっても混合気に安定して点火できることは、第１実施形態と同じである。点火プラグ４０１０に流れる電流が減少し単位放電体積あたりの消費エネルギーが減少することも、第１実施形態と同じである。 As in the first embodiment, the exposed portion 4040 of the floating electrode 4026 is relatively close to the exposed portion 4030 of the center electrode 4022, and the metal shell 4024 is relatively far from the exposed portion 4030 of the center electrode 4022. The capacitance C1 between the center electrode 4022 and the floating electrode 4026 is relatively small, and the capacitance C2 between the floating electrode 4026 and the metal shell 4024 is relatively large. Therefore, when a pulse voltage is applied between the center electrode 4022 and the metal shell 4024, a high voltage is induced between the center electrode 4022 and the floating electrode 4026, and the exposed portion 4030 of the center electrode 4022 and the floating electrode 4026 A powerful streamer discharge is generated between the exposed portion 4040 and the exposed portion 4040. This powerful streamer discharge ignites the air-fuel mixture. It is the same as in the first embodiment that the air-fuel mixture can be ignited stably even when the discharge volume is large and the combustion is difficult. It is the same as in the first embodiment that the current flowing through the spark plug 4010 decreases and the energy consumption per unit discharge volume decreases.

　（碍子の二重構造）
　図１９及び図２０に示すように、碍子４０２０は、鞘４０９０及び芯４０９２を備える。鞘４０９０の内周面には、収容溝４２７２が形成される。芯４０９２は、保持軸４２７０を備える。図２１に示すように、浮遊電極４０２６の被埋設部４０４２は、管形状部４１２０及び棒形状部４１２２を備える。管形状部４１２０には保持軸４２７０が差し込まれ、浮遊電極４０２６は芯４０９２に固定される。浮遊電極４０２６が固定された芯４０９２は、鞘４０９０に収容される。このとき、棒形状部４１２２は収容溝４２７２に収容される。これにより、浮遊電極４０６６の被埋設部４０４２は、碍子４０２０に埋設される。図１９に示すように、鞘４０９０と芯４０９２との間隙には、Ｏリング４３２０が挟まれる。これにより、鞘４０９０と芯４０９２との間隙から混合気が漏れにくくなる。 (Double structure of eggplant)
As shown in FIGS. 19 and 20, the insulator 4020 includes a sheath 4090 and a core 4092. An accommodation groove 4272 is formed on the inner peripheral surface of the sheath 4090. The core 4092 includes a holding shaft 4270. As shown in FIG. 21, the embedded portion 4042 of the floating electrode 4026 includes a tube-shaped portion 4120 and a rod-shaped portion 4122. A holding shaft 4270 is inserted into the tube-shaped portion 4120, and the floating electrode 4026 is fixed to the core 4092. The core 4092 to which the floating electrode 4026 is fixed is accommodated in the sheath 4090. At this time, the bar-shaped portion 4122 is received in the receiving groove 4272. Thereby, the embedded portion 4042 of the floating electrode 4066 is embedded in the insulator 4020. As shown in FIG. 19, an O-ring 4320 is sandwiched between the sheath 4090 and the core 4092. This makes it difficult for the air-fuel mixture to leak from the gap between the sheath 4090 and the core 4092.

　（浮遊電極の露出部の数）
　図１９に示すように、浮遊電極４０２６は、２個の露出部４０４０を備える。これにより、放電体積が大きくなる。浮遊電極４０２６の露出部４０４０の数が増減されてもよい。 (Number of exposed parts of floating electrode)
As shown in FIG. 19, the floating electrode 4026 includes two exposed portions 4040. This increases the discharge volume. The number of exposed portions 4040 of the floating electrode 4026 may be increased or decreased.

　｛第５実施形態｝
　（概略）
　第５実施形態は、第１実施形態の点火プラグを置き換える点火プラグに関する。以下では、第１実施形態の点火プラグと第５実施形態の点火プラグとの重要な共通点及び相違点が説明される。説明されない事項については、第１実施形態又はその他の実施形態の点火プラグの構成が、そのまま又は変形されてから、第５実施形態の点火プラグにおいて採用される。第５実施形態の点火プラグの構成物には、第１実施形態の点火プラグの対応する構成物と同じ名称が付与される。 {Fifth embodiment}
(Outline)
The fifth embodiment relates to a spark plug that replaces the spark plug of the first embodiment. In the following, important common points and differences between the spark plug of the first embodiment and the spark plug of the fifth embodiment will be described. About the matter which is not demonstrated, the structure of the spark plug of 1st Embodiment or another embodiment is employ | adopted in the spark plug of 5th Embodiment as it is or after changing. The components of the spark plug of the fifth embodiment are given the same names as the corresponding components of the spark plug of the first embodiment.

　図２２の模式図は、第５実施形態の点火プラグの斜視図である。図２３の模式図は、第５実施形態の点火プラグの断面図である。図２４の模式図は、第５実施形態の碍子の分解斜視図である。図２５の模式図は、第５実施形態の浮遊電極の斜視図である。 22 is a perspective view of the spark plug of the fifth embodiment. The schematic diagram of FIG. 23 is sectional drawing of the ignition plug of 5th Embodiment. The schematic diagram of FIG. 24 is an exploded perspective view of the insulator of 5th Embodiment. The schematic diagram of FIG. 25 is a perspective view of the floating electrode of the fifth embodiment.

　図２２及び図２３に示すように、点火プラグ５０１０は、第１実施形態と同じく、碍子５０２０、中心電極５０２２、主体金具５０２４及び浮遊電極５０２６を備える。主体金具５０２４は、露出部５３３０を備える。中心電極５０２２は、被埋設部５０３２を備える。浮遊電極５０２６は、露出部５０４０及び被埋設部５０４２を備える。中心電極５０２２の被埋設部５０３２は、高圧の中心電極５０２２を絶縁するために設けられる。浮遊電極５０２６の被埋設部５０４２は、中心電極５０２２と浮遊電極５０２６との間の静電容量Ｃ１を大きくするために設けられる。 22 and 23, the spark plug 5010 includes an insulator 5020, a center electrode 5022, a metal shell 5024, and a floating electrode 5026, as in the first embodiment. The metal shell 5024 includes an exposed portion 5330. The center electrode 5022 includes an embedded portion 5032. The floating electrode 5026 includes an exposed portion 5040 and an embedded portion 5042. The buried portion 5032 of the center electrode 5022 is provided to insulate the high-voltage center electrode 5022. The buried portion 5042 of the floating electrode 5026 is provided to increase the capacitance C1 between the center electrode 5022 and the floating electrode 5026.

　浮遊電極５０２６の露出部５０４０は主体金具５０２４の露出部５３３０に相対的に近く、中心電極５０２２は主体金具５０２４の露出部５３３０から相対的に遠い。第１実施形態とは逆に、中心電極５０２２と浮遊電極５０２６との間の静電容量Ｃ１は相対的に大きく、浮遊電極５０２６と主体金具５０２４との間の静電容量Ｃ２は相対的に小さい。したがって、中心電極５０２２と主体金具５０２４との間にパルス電圧が印加された場合は、第１実施形態とは異なり、浮遊電極５０２６と主体金具５０２４との間に高圧が誘起され、浮遊電極５０２６の露出部５０４０と主体金具５０２４の露出部５３３０との間に強力なストリーマ放電が発生する。この強力なストリーマ放電により、混合気が点火される。放電体積が大きくなり難燃焼条件であっても混合気に安定して点火できることは、第１実施形態と同じである。点火プラグ５０１０に流れる電流が減少し単位放電体積あたりの消費エネルギーが減少することも、第１実施形態と同じである。 The exposed portion 5040 of the floating electrode 5026 is relatively close to the exposed portion 5330 of the metal shell 5024, and the center electrode 5022 is relatively far from the exposed portion 5330 of the metal shell 5024. Contrary to the first embodiment, the capacitance C1 between the center electrode 5022 and the floating electrode 5026 is relatively large, and the capacitance C2 between the floating electrode 5026 and the metal shell 5024 is relatively small. . Therefore, when a pulse voltage is applied between the center electrode 5022 and the metal shell 5024, unlike the first embodiment, a high voltage is induced between the floating electrode 5026 and the metal shell 5024, and the floating electrode 5026 A powerful streamer discharge is generated between the exposed portion 5040 and the exposed portion 5330 of the metal shell 5024. This powerful streamer discharge ignites the air-fuel mixture. It is the same as in the first embodiment that the air-fuel mixture can be ignited stably even when the discharge volume is large and the combustion is difficult. It is the same as in the first embodiment that the current flowing through the spark plug 5010 decreases and the energy consumption per unit discharge volume decreases.

　（電極の位置の関係）
　図２６の模式図は、第５実施形態の電極の位置の関係を示す。 (Relationship of electrode position)
The schematic diagram of FIG. 26 shows the positional relationship of the electrodes of the fifth embodiment.

　図２６に示すように、浮遊電極５０２６の露出部５０４０は主体金具５０２４の露出部５３３０に相対的に近く、中心電極５０２２は主体金具５０２４の露出部５３３０から相対的に遠い。したがって、浮遊電極５０２６の露出部５０４０から燃焼室９００２を経由して主体金具５０２４の露出部５３３０までの放電経路長Ｌ１は相対的に短く、中心電極５０２２から燃焼室９００２を経由して主体金具５０２４の露出部５３３０までの放電経路長Ｌ２は相対的に長く、Ｌ１＜Ｌ２が成立する。浮遊電極５０２６の露出部５０４０と主体金具５０２４の露出部５３３０との放電ギャップは、中心電極５０２２と主体金具５０２４の露出部５３３０との放電ギャップより狭い。このため、中心電極５０２２と浮遊電極５０２６の露出部５０４０との間には相対的に放電が発生しにくい。また、浮遊電極５０２６の露出部５０４０と主体金具５０２４の露出部５３３０との間には相対的に放電が発生しやすい。 26, the exposed portion 5040 of the floating electrode 5026 is relatively close to the exposed portion 5330 of the metal shell 5024, and the center electrode 5022 is relatively far from the exposed portion 5330 of the metal shell 5024. Therefore, the discharge path length L1 from the exposed portion 5040 of the floating electrode 5026 to the exposed portion 5330 of the metal shell 5024 via the combustion chamber 9002 is relatively short, and the metal shell 5024 from the center electrode 5022 via the combustion chamber 9002 is relatively short. The discharge path length L2 to the exposed portion 5330 is relatively long, and L1 <L2 is established. The discharge gap between the exposed portion 5040 of the floating electrode 5026 and the exposed portion 5330 of the metal shell 5024 is narrower than the discharge gap between the center electrode 5022 and the exposed portion 5330 of the metal shell 5024. For this reason, a discharge is relatively unlikely to occur between the center electrode 5022 and the exposed portion 5040 of the floating electrode 5026. In addition, a discharge is relatively easily generated between the exposed portion 5040 of the floating electrode 5026 and the exposed portion 5330 of the metal shell 5024.

　（静電容量の関係）
　第１実施形態の説明において言及した式（１）及び（２）からは、中心電極５０２２と浮遊電極５０２６との間の静電容量Ｃ１が大きく浮遊電極５０２６と主体金具５０２４の間の静電容量Ｃ２が小さい場合は、中心電極５０２２と浮遊電極５０２６との間の電圧Ｖ１が低く浮遊電極５０２６と主体金具５０２４との間の電圧Ｖ２が高いことが導かれる。このため、第１実施形態とは逆に、Ｃ２＜Ｃ１が成立する場合は、Ｖ１＜Ｖ２が成立し、中心電極５０２２と主体金具５０２４との間にパルス電圧が印加された場合に浮遊電極５０２６と主体金具５０２４との間に高圧が誘起される。これにより、浮遊電極５０２６の露出部５０４０と主体金具５０２４の露出部５３３０との間に放電が発生しやすくなり、中心電極５０２２と浮遊電極５０２６の露出部５０４０との間に放電が発生しにくくなる。静電容量Ｃ１は、少なくとも静電容量Ｃ２より大きく、望ましくは静電容量Ｃ２の１０倍以上である。 (Capacitance relationship)
From the formulas (1) and (2) mentioned in the description of the first embodiment, the capacitance C1 between the center electrode 5022 and the floating electrode 5026 is large, and the capacitance between the floating electrode 5026 and the metal shell 5024 is large. When C2 is small, it is derived that the voltage V1 between the center electrode 5022 and the floating electrode 5026 is low and the voltage V2 between the floating electrode 5026 and the metal shell 5024 is high. Therefore, contrary to the first embodiment, when C2 <C1 is satisfied, V1 <V2 is satisfied, and the floating electrode 5026 is applied when a pulse voltage is applied between the center electrode 5022 and the metal shell 5024. A high pressure is induced between the metal shell 5024 and the metal shell 5024. As a result, a discharge is likely to occur between the exposed portion 5040 of the floating electrode 5026 and the exposed portion 5330 of the metal shell 5024, and a discharge is less likely to occur between the center electrode 5022 and the exposed portion 5040 of the floating electrode 5026. . The electrostatic capacitance C1 is at least larger than the electrostatic capacitance C2, and preferably 10 times or more of the electrostatic capacitance C2.

　（露出部及び被埋設部）
　図２３に示すように、主体金具５０２４の露出部５３３０及び浮遊電極５０２６の露出部５０４０は、碍子５０２０の外部に露出し、燃焼室９００２に露出する。これにより、燃焼室９００２に放電が発生し、放電により混合気に点火できる。中心電極５０２２の被埋設部５０３２及び浮遊電極５０２６の被埋設部５０４２は、碍子５０２０に埋設される。第１実施形態と異なり、中心電極５０２２は、点火プラグ５０１０の軸方向先端側に露出せず、燃焼室９００２に露出しない。これにより、中心電極５０２２と主体金具５０２４の露出部５３３０とが碍子５０２０で隔てられ、中心電極５０２２と主体金具５０２４の露出部５３３０との間に放電が発生しにくくなる。また、中心電極５０２２と浮遊電極５０２６の露出部５０４０とが碍子５０２０で隔てられ、中心電極５０２２と浮遊電極５０２６の露出部５０４０との間に放電が発生しにくくなる。ただし、中心電極５０２２が第１実施形態と同じく露出部を有してもよい。 (Exposed part and buried part)
As shown in FIG. 23, the exposed portion 5330 of the metal shell 5024 and the exposed portion 5040 of the floating electrode 5026 are exposed to the outside of the insulator 5020 and exposed to the combustion chamber 9002. As a result, a discharge is generated in the combustion chamber 9002, and the mixture can be ignited by the discharge. The embedded portion 5032 of the center electrode 5022 and the embedded portion 5042 of the floating electrode 5026 are embedded in the insulator 5020. Unlike the first embodiment, the center electrode 5022 is not exposed to the axial front end side of the spark plug 5010 and is not exposed to the combustion chamber 9002. As a result, the center electrode 5022 and the exposed portion 5330 of the metal shell 5024 are separated by the insulator 5020, and it is difficult for electric discharge to occur between the center electrode 5022 and the exposed portion 5330 of the metal shell 5024. In addition, the center electrode 5022 and the exposed portion 5040 of the floating electrode 5026 are separated by the insulator 5020, so that it is difficult for discharge to occur between the center electrode 5022 and the exposed portion 5040 of the floating electrode 5026. However, the center electrode 5022 may have an exposed portion as in the first embodiment.

　（主体金具）
　図２３に示すように、主体金具５０２４には、第１実施形態と同じく、丸孔５０６０が形成される。丸孔５０６０の内部は、碍子５０２０等を収容する収容空間になる。主体金具５０２４が「主体金具」とは呼びがたい形成物に置き換えられてもよい。丸孔５０６０が他の形状を持つ孔に置き換えられてもよい。 (Main metal fittings)
As shown in FIG. 23, a round hole 5060 is formed in the metal shell 5024 as in the first embodiment. The inside of the round hole 5060 becomes an accommodation space for accommodating the insulator 5020 and the like. The metal shell 5024 may be replaced with a formation that is difficult to call “metal metal”. The round hole 5060 may be replaced with a hole having another shape.

　主体金具５０２４の少なくとも一部は露出するが、主体金具５０２４の外周面５０７２の一部が絶縁体に被覆されてもよい。主体金具５０２４の一部が碍子５０２０に埋設されてもよい。 Although at least a part of the metal shell 5024 is exposed, a part of the outer peripheral surface 5072 of the metal shell 5024 may be covered with an insulator. A part of the metal shell 5024 may be embedded in the insulator 5020.

　（浮遊電極の被埋設部による静電容量Ｃ１の増加）
　浮遊電極５０２６の露出部５０４０が主体金具５０２４の露出部５３３０に近づけられ、中心電極５０２２が主体金具５０２４の露出部５３３０から遠ざけられた場合は、中心電極５０２２と浮遊電極５０２６との間の静電容量Ｃ１が小さくなりやすく、浮遊電極５０２６と主体金具５０２４との間の静電容量Ｃ２が大きくなりやすい。このため、静電容量の関係Ｃ２＜Ｃ１が満たされるように浮遊電極５０２６に被埋設部５０４２が設けられる。 (Increase in capacitance C1 due to the buried portion of the floating electrode)
When the exposed portion 5040 of the floating electrode 5026 is brought close to the exposed portion 5330 of the metal shell 5024 and the center electrode 5022 is moved away from the exposed portion 5330 of the metal shell 5024, the electrostatic capacitance between the center electrode 5022 and the floating electrode 5026 is The capacitance C1 tends to be small, and the capacitance C2 between the floating electrode 5026 and the metal shell 5024 tends to be large. Therefore, the embedded portion 5042 is provided in the floating electrode 5026 so that the capacitance relationship C2 <C1 is satisfied.

　図２３及び図２５に示すように、浮遊電極５０２６の被埋設部５０４２は、管形状部５１２０を備える。管形状部５１２０の管内は、碍子５０２０等が充填される内部空間になる。碍子５０２０は、管形状部５１２０の管内に充填される被充填部５７００を備える。中心電極５０２２の被埋設部５０３２は、棒形状部５７０２を備える。棒形状部５７０２は、管形状部５１２０の管内に配置され、被充填部５７００に埋設される。管形状部５１２０は、棒形状部５７０２の周りを一周する。これにより、中心電極５０２２と浮遊電極５０２６とが広範囲に渡って碍子５０２０を挟んで対向する。管形状部５１２０と棒形状部５７０２との間隙は、碍子５０２０で埋められる。当該間隙には、空隙が存在しない。このため、中心電極５０２２と浮遊電極５０２６との間の静電容量Ｃ２が大きくなる。ただし、当該間隙に若干の空隙が存在してもよい。 23 and 25, the embedded portion 5042 of the floating electrode 5026 includes a tube-shaped portion 5120. The inside of the tube-shaped portion 5120 is an internal space filled with the insulator 5020 and the like. The insulator 5020 includes a filled portion 5700 that is filled in the tube of the tube-shaped portion 5120. The embedded portion 5032 of the center electrode 5022 includes a rod-shaped portion 5702. The rod-shaped portion 5702 is disposed in the tube of the tube-shaped portion 5120 and is embedded in the filled portion 5700. The tube-shaped portion 5120 makes a round around the rod-shaped portion 5702. Thereby, the center electrode 5022 and the floating electrode 5026 face each other across the insulator 5020 over a wide range. A gap between the tube-shaped portion 5120 and the rod-shaped portion 5702 is filled with an insulator 5020. There are no voids in the gap. For this reason, the electrostatic capacitance C2 between the center electrode 5022 and the floating electrode 5026 increases. However, a slight gap may exist in the gap.

　管形状部５１２０が設けられることには、中心電極５０２２と浮遊電極５０２６と対向する範囲が広がり、中心電極５０２２と浮遊電極５０２６との間の静電容量Ｃ１が大きくなるという利点がある。しかし、管形状部５１２０に代えて、又は、管形状部５１２０に加えて、中心電極５０２２の被埋設部５０３２との間に大きな静電容量を形成する構造物が設けられてもよい。例えば、多数の棒形状部、コイル形状部、板形状部等が設けられてもよい。棒形状部５７０２に代えて、又は、棒形状部５７０２に加えて、浮遊電極５０２６との間に大きな静電容量を形成する構造物が設けられてもよい。例えば、管形状部等が設けられてもよい。 The provision of the tube-shaped portion 5120 has an advantage that a range where the center electrode 5022 and the floating electrode 5026 are opposed to each other is widened, and an electrostatic capacitance C1 between the center electrode 5022 and the floating electrode 5026 is increased. However, instead of the tube-shaped portion 5120 or in addition to the tube-shaped portion 5120, a structure that forms a large capacitance between the embedded portion 5032 of the center electrode 5022 may be provided. For example, many rod-shaped parts, coil-shaped parts, plate-shaped parts, etc. may be provided. Instead of the bar-shaped portion 5702, or in addition to the bar-shaped portion 5702, a structure that forms a large capacitance between the floating electrode 5026 and the structure may be provided. For example, a tube-shaped part or the like may be provided.

　管形状部５１２０と棒形状部５７０２とは同軸配置される。これにより、棒形状部５７０２の外周面から管形状部５１２０の内周面までの距離が均一になり、電界の偏りが抑制される。 The tube-shaped portion 5120 and the rod-shaped portion 5702 are arranged coaxially. Thereby, the distance from the outer peripheral surface of the rod-shaped part 5702 to the inner peripheral surface of the tube-shaped part 5120 becomes uniform, and the bias of the electric field is suppressed.

　（碍子）
　図２３に示すように、碍子５０２０は、被収容部５０８０を備える。被収容部５０８０は、丸孔５０６０の内部に収容される。 (insulator)
As shown in FIG. 23, the insulator 5020 includes a accommodated portion 5080. The accommodated portion 5080 is accommodated inside the round hole 5060.

　被収容部５０８０は、被中空保持部５３４０を備える。被中空保持部５３４０は、丸孔５０６０の内部に中空保持される。これにより、丸孔５０６０の内部で碍子５０２０が空隙に囲まれ、浮遊電極５０２６と主体金具５０２４との間の静電容量Ｃ２が小さくなる。 The accommodated part 5080 includes a hollow retained part 5340. The hollow holding portion 5340 is hollowly held inside the round hole 5060. As a result, the insulator 5020 is surrounded by the gap inside the round hole 5060, and the capacitance C2 between the floating electrode 5026 and the metal shell 5024 is reduced.

　（浮遊電極の露出部の突出）
　図２３に示すように、浮遊電極５０２６の露出部５０４０は、被収容部５０８０の外部に突出し、丸孔５０６０の外部に突出し、中心電極５０２２から離れる。これにより、中心電極５０２２と浮遊電極５０２６の露出部５０４０との間に放電が発生しにくくなる。 (Protrusion of exposed part of floating electrode)
As shown in FIG. 23, the exposed portion 5040 of the floating electrode 5026 protrudes outside the accommodated portion 5080, protrudes outside the round hole 5060, and is separated from the center electrode 5022. This makes it difficult for discharge to occur between the center electrode 5022 and the exposed portion 5040 of the floating electrode 5026.

　（浮遊電極の露出部の棒先端）
　図２２及び図２３に示すように、浮遊電極５０２６の露出部５０４０は、棒形状を持ち、棒先端５０５２を有する。これにより、浮遊電極５０２６の露出部５０４０に電界が集中し、浮遊電極５０２６の露出部５０４０と主体金具５０２４の露出部５３３０との間に放電が発生しやすくなる。ただし、浮遊電極５０２６の露出部５０４０が他の形状を持ってもよい。 (Bar tip of exposed part of floating electrode)
As shown in FIGS. 22 and 23, the exposed portion 5040 of the floating electrode 5026 has a rod shape and has a rod tip 5052. As a result, the electric field concentrates on the exposed portion 5040 of the floating electrode 5026, and electric discharge easily occurs between the exposed portion 5040 of the floating electrode 5026 and the exposed portion 5330 of the metal shell 5024. However, the exposed portion 5040 of the floating electrode 5026 may have other shapes.

　浮遊電極５０２６の露出部５０４０の棒先端５０５２は、点火プラグ５０１０の径方向外側を向く。これにより、浮遊電極５０２６の露出部５０４０の棒先端５０５２が主体金具５０２４に近づく方向を向き、浮遊電極５０２６の露出部５０４０と主体金具５０２４の露出部５３３０との間に放電が発生しやすくなる。ただし、浮遊電極５０２６の露出部５０４０の棒先端５０５２が他の方向を向いてもよい。例えば、浮遊電極５０２６の露出部５０４０の棒先端５０５２が点火プラグ５０１０の軸方向先端側を向いてもよい。 The rod tip 5052 of the exposed portion 5040 of the floating electrode 5026 faces the radially outer side of the spark plug 5010. As a result, the rod tip 5052 of the exposed portion 5040 of the floating electrode 5026 faces in the direction approaching the metal shell 5024, and electric discharge is likely to occur between the exposed portion 5040 of the floating electrode 5026 and the exposed portion 5330 of the metal shell 5024. However, the rod tip 5052 of the exposed portion 5040 of the floating electrode 5026 may face another direction. For example, the rod tip 5052 of the exposed portion 5040 of the floating electrode 5026 may face the tip side in the axial direction of the spark plug 5010.

　（碍子の二重構造）
　図２３及び図２４に示すように、碍子５０２０は、鞘５０９０及び芯５０９２を備える。鞘５０９０の内周面には、収容溝５２７２が形成される。芯５０９２は、保持軸５２７０を備える。図２５に示すように、浮遊電極５０２６の被埋設部５０４２は、管形状部５１２０及び棒形状部５１２２を備える。管形状部５１２０には保持軸５２７０が差し込まれ、浮遊電極５０２６は芯５０９２に固定される。浮遊電極５０２６が固定された芯５０９２は、鞘５０９０に収容される。このとき、棒形状部５１２２は収容溝５２７２に収容される。これにより、浮遊電極５０２６の被埋設部５０４２は、碍子５０２０に埋設される。鞘５０９０と芯５０９２との間隙には、Ｏリング５３２０が挟まれる。これにより、鞘５０９０と芯５０９２との間隙から混合気が漏れにくくなる。 (Double structure of eggplant)
As shown in FIGS. 23 and 24, the insulator 5020 includes a sheath 5090 and a core 5092. A housing groove 5272 is formed on the inner peripheral surface of the sheath 5090. The core 5092 includes a holding shaft 5270. As shown in FIG. 25, the embedded portion 5042 of the floating electrode 5026 includes a tube-shaped portion 5120 and a rod-shaped portion 5122. A holding shaft 5270 is inserted into the tube-shaped portion 5120, and the floating electrode 5026 is fixed to the core 5092. The core 5092 to which the floating electrode 5026 is fixed is accommodated in the sheath 5090. At this time, the bar-shaped portion 5122 is received in the receiving groove 5272. Thereby, the embedded portion 5042 of the floating electrode 5026 is embedded in the insulator 5020. An O-ring 5320 is sandwiched in the gap between the sheath 5090 and the core 5092. This makes it difficult for the air-fuel mixture to leak from the gap between the sheath 5090 and the core 5092.

　（浮遊電極）
　浮遊電極５０２６に代えて、図２７に示すように、互いに絶縁された２個以上の浮遊電極５０２６ａが設けられてもよい。これにより、２個以上の浮遊電極５０２６ａの電位が独立し、一の浮遊電極５０２６ａと主体金具５０２４との間に放電が発生しても、他の浮遊電極５０２６ａと主体金具５０２４との間の放電が阻害されず、多点放電が発生しやすくなる。 (Floating electrode)
Instead of the floating electrode 5026, as shown in FIG. 27, two or more floating electrodes 5026a insulated from each other may be provided. Accordingly, the potentials of two or more floating electrodes 5026a are independent, and even if a discharge occurs between one floating electrode 5026a and the metal shell 5024, the discharge between the other floating electrode 5026a and the metal shell 5024 occurs. Is not hindered, and multipoint discharge is likely to occur.

　｛第６実施形態｝
　（概略）
　第６実施形態は、第１実施形態の点火プラグを置き換える点火プラグに関する。以下では、第１実施形態の点火プラグと第６実施形態の点火プラグとの重要な共通点及び相違点が説明される。説明されない事項については、第１実施形態又はその他の実施形態の点火プラグの構成が、そのまま又は変形されてから、第６実施形態の点火プラグにおいて採用される。第６実施形態の点火プラグの構成物には、第１実施形態の点火プラグの対応する構成物と同じ名称が付与される。 {Sixth embodiment}
(Outline)
The sixth embodiment relates to a spark plug that replaces the spark plug of the first embodiment. In the following, important common points and differences between the spark plug of the first embodiment and the spark plug of the sixth embodiment will be described. About the matter which is not demonstrated, after the structure of the spark plug of 1st Embodiment or another embodiment is changed as it is or is deform | transformed, it is employ | adopted in the spark plug of 6th Embodiment. The components of the spark plug of the sixth embodiment are given the same names as the corresponding components of the spark plug of the first embodiment.

　図２８の模式図は、第６実施形態の点火プラグの斜視図である。図２９の回路図は、第６実施形態の点火プラグの等価回路を示す。 28 is a perspective view of the spark plug of the sixth embodiment. The circuit diagram of FIG. 29 shows an equivalent circuit of the spark plug of the sixth embodiment.

　図２８及び図２９に示すように、点火プラグ６０１０は、碍子６０２０、中心電極６０２２、主体金具６０２４、浮遊電極６０２６及びキャパシタ６３５０を備える。中心電極６０２２は、露出部６０３０及び被埋設部６０３２を備える。浮遊電極６０２６は、露出部６０４０を備える。キャパシタ６３５０の一方の端子は浮遊電極６０２６に電気的に接続される。キャパシタ６３５０の他方の端子は主体金具６０２４に電気的に接続される。キャパシタ６３５０は、碍子６０２０に外付けされる。中心電極６０２２の被埋設部６０３２は、高圧の中心電極６０２２を絶縁するために設けられる。 28 and 29, the spark plug 6010 includes an insulator 6020, a center electrode 6022, a metal shell 6024, a floating electrode 6026, and a capacitor 6350. The center electrode 6022 includes an exposed portion 6030 and an embedded portion 6032. The floating electrode 6026 includes an exposed portion 6040. One terminal of the capacitor 6350 is electrically connected to the floating electrode 6026. The other terminal of the capacitor 6350 is electrically connected to the metal shell 6024. Capacitor 6350 is externally attached to insulator 6020. The embedded portion 6032 of the center electrode 6022 is provided to insulate the high-voltage center electrode 6022.

　中心電極６０２２の露出部６０３０及び浮遊電極６０２６の露出部６０４０は、碍子６０２０の外部に露出する。中心電極６０２２の被埋設部６０３２は、碍子６０２０に埋設される。浮遊電極６０２６が被埋設部を備えてもよい。 The exposed portion 6030 of the center electrode 6022 and the exposed portion 6040 of the floating electrode 6026 are exposed to the outside of the insulator 6020. The embedded portion 6032 of the center electrode 6022 is embedded in the insulator 6020. The floating electrode 6026 may include a buried portion.

　第１実施形態と同じく、浮遊電極６０２６の露出部６０４０は中心電極６０２２の露出部６０３０に相対的に近く、主体金具６０２４は中心電極６０２２の露出部６０３０から相対的に遠い。中心電極６０２２と浮遊電極６０２６との間の静電容量Ｃ１及び浮遊電極６０２６と主体金具６０２４との間の静電容量Ｃ２は、第１実施形態の説明において言及した静電容量の関係Ｃ１＜Ｃ２を必ずしも満たさない。しかし、静電容量Ｃ１は相対的に小さく、静電容量Ｃ２及びキャパシタ６３５０の静電容量Ｃ３の和Ｃ２＋Ｃ３は相対的に大きく、Ｃ１＜Ｃ２＋Ｃ３が成立する。したがって、中心電極６０２２と主体金具６０２４との間にパルス電圧が印加された場合は、中心電極６０２２と浮遊電極６０２６との間に高圧が誘起され、中心電極６０２２の露出部６０３０と浮遊電極６０２６の露出部６０４０との間に強力なストリーマ放電が発生する。この強力なストリーマ放電により、混合気が点火される。放電体積が大きくなり難燃焼条件であっても混合気に安定して点火できることは、第１実施形態と同じである。点火プラグ６０１０に流れる電流が減少し単位放電体積あたりの消費エネルギーが減少することも、第１実施形態と同じである。 As in the first embodiment, the exposed portion 6040 of the floating electrode 6026 is relatively close to the exposed portion 6030 of the center electrode 6022, and the metal shell 6024 is relatively far from the exposed portion 6030 of the center electrode 6022. The capacitance C1 between the center electrode 6022 and the floating electrode 6026 and the capacitance C2 between the floating electrode 6026 and the metal shell 6024 are the capacitance relationship C1 <C2 mentioned in the description of the first embodiment. Does not necessarily satisfy. However, the capacitance C1 is relatively small, and the sum C2 + C3 of the capacitance C2 and the capacitance C3 of the capacitor 6350 is relatively large, and C1 <C2 + C3 is established. Accordingly, when a pulse voltage is applied between the center electrode 6022 and the metal shell 6024, a high voltage is induced between the center electrode 6022 and the floating electrode 6026, and the exposed portion 6030 of the center electrode 6022 and the floating electrode 6026 A powerful streamer discharge is generated between the exposed portion 6040 and the exposed portion 6040. This powerful streamer discharge ignites the air-fuel mixture. It is the same as in the first embodiment that the air-fuel mixture can be ignited stably even when the discharge volume is large and the combustion is difficult. It is the same as in the first embodiment that the current flowing through the spark plug 6010 decreases and the energy consumption per unit discharge volume decreases.

　浮遊電極６０２６に代えて、図３０に示すように王冠形状を持つ浮遊電極６０２６ａが用いられてもよい。図３１に示すように棒形状を持ち互いに絶縁された２個以上の浮遊電極６０２６ｂが用いられてもよい。図３２に示すように膜形状を持ち互いに絶縁された２個以上の浮遊電極６０２６ｃが用いられてもよい。 Instead of the floating electrode 6026, a floating electrode 6026a having a crown shape as shown in FIG. 30 may be used. As shown in FIG. 31, two or more floating electrodes 6026b having a rod shape and insulated from each other may be used. As shown in FIG. 32, two or more floating electrodes 6026c having a film shape and insulated from each other may be used.

　図３３のグラフは、圧力及び電圧による放電の形態の変化を示す。図３３からは、キャパシタが外付けされた場合は、キャパシタが外付けされない場合よりも、放電が発生しやすくなることが理解される。一方、アーク放電が発生する電圧はキャパシタの有無に影響されない。したがって、キャパシタが外付けされた場合は、ストリーマ放電が発生する範囲が広がる。 33 is a graph showing changes in the form of discharge due to pressure and voltage. From FIG. 33, it is understood that discharge is more likely to occur when a capacitor is externally attached than when a capacitor is not externally attached. On the other hand, the voltage at which arc discharge occurs is not affected by the presence or absence of a capacitor. Therefore, when a capacitor is externally attached, the range in which streamer discharge occurs is widened.

　本発明は詳細に示され記述されたが、上記の記述は全ての局面において例示であって限定的ではない。しがって、本発明の範囲からはずれることなく無数の修正及び変形が案出されうると解される。 Although the present invention has been shown and described in detail, the above description is illustrative in all aspects and not limiting. Thus, it will be appreciated that numerous modifications and variations can be devised without departing from the scope of the invention.

　１０００　点火装置
　１０１０，２０１０，３０１０，４０１０，５０１０，６０１０　点火プラグ
　１０１２　パルス電圧印加機構
　１０２０，２０２０，３０２０，４０２０，５０２０，６０２０　碍子
　１０２２，２０２２，３０２２，４０２２，５０２２，６０２２　中心電極
　１０２４，２０２４，３０２４，４０２４，５０２４，６０２４　主体金具
　１０２６，２０２６，３０２６，４０２６，５０２６，６０２６　浮遊電極
　１０３０，２０３０，３０３０，４０３０，６０３０　中心電極の露出部
　１０３２，２０３２，３０３２，４０３２，５０３２，６０３２　中心電極の被埋設部
　１０４０，２０４０，３０４０，４０４０，５０４０，６０４０　浮遊電極の露出部
　１０４２，２０４２，３０４２，４０４２，５０４２　浮遊電極の被埋設部
　５３３０　主体金具の露出部
　６３５０　キャパシタ 1000 Ignition device 1010, 2010, 3010, 4010, 5010, 6010 Spark plug 1012 Pulse voltage application mechanism 1020, 2020, 3020, 4020, 5020, 6020 Insulator 1022, 2022, 3022, 4022, 5022, 6022 Central electrode 1024, 2024 3024, 4024, 5024, 6024 Metal shell 1026, 2026, 3026, 4026, 5026, 6026 Floating electrode 1030, 2030, 3030, 4030, 6030 Exposed portion of center electrode 1032, 2032, 3032, 4032, 5032, 6032 Embedded part 1040, 2040, 3040, 4040, 5040, 6040 Floating electrode exposed part 1042, 2042, 3042, 4042, 5042 Floating electrode embedded part 5 330 Exposed portion of metal shell 6350 Capacitor

Claims (19)

　点火プラグであって、
　碍子と、
　前記碍子の外部に露出する第１の露出部及び前記碍子に埋設される第１の被埋設部を備える高圧電極と、
　前記第１の露出部から相対的に遠い接地電極と、
　前記碍子の外部に露出する第２の露出部及び前記碍子に埋設される第２の被埋設部を備え、前記第２の露出部が前記第１の露出部に相対的に近く、前記高圧電極との間に相対的に小さな静電容量を持ち、前記接地電極との間に相対的に大きな静電容量を持つ浮遊電極と、
を備える点火プラグ。 A spark plug,
With Reiko,
A high voltage electrode comprising a first exposed portion exposed to the outside of the insulator and a first embedded portion embedded in the insulator;
A ground electrode relatively far from the first exposed portion;
A second exposed portion exposed outside the insulator and a second embedded portion embedded in the insulator, wherein the second exposed portion is relatively close to the first exposed portion, and the high-voltage electrode A floating electrode having a relatively small capacitance between the ground electrode and a relatively large capacitance between the ground electrode,
With spark plug. 　請求項１の点火プラグにおいて、
　前記接地電極に収容空間が形成され、
　前記碍子は、
　前記収容空間に収容される被収容部
を備え、
　前記第２の被埋設部は、
　前記被収容部に埋設される構造物
を備える
点火プラグ。 The spark plug of claim 1.
A storage space is formed in the ground electrode,
The eggplant is
A portion to be accommodated to be accommodated in the accommodation space;
The second embedded portion is
A spark plug comprising a structure embedded in the receiving portion. 　請求項２の点火プラグにおいて、
　前記収容空間は、前記構造物の周りを一周する内周面を有する丸孔の内部であり、
　前記構造物は、前記内周面と対向する外周面を有する管形状部である
点火プラグ。 The spark plug of claim 2.
The accommodating space is an inside of a round hole having an inner peripheral surface that goes around the structure.
The said structure is a spark plug which is a pipe-shaped part which has the outer peripheral surface facing the said inner peripheral surface. 　請求項１の点火プラグにおいて、
　前記碍子に中空空間が形成され、
　前記第１の被埋設部は、
　前記中空空間の内部に中空保持される被中空保持部
を備える
点火プラグ。 The spark plug of claim 1.
A hollow space is formed in the insulator,
The first embedded portion is
A spark plug including a hollow holding portion that is hollowly held inside the hollow space. 　請求項１の点火プラグにおいて、
　前記接地電極に収容空間が形成され、
　前記碍子は、
　前記収容空間の外部へ突出する突出部、
を備え、
　前記第１の露出部及び前記第２の露出部が前記突出部からさらに突出する
点火プラグ。 The spark plug of claim 1.
A storage space is formed in the ground electrode,
The eggplant is
A projecting portion projecting to the outside of the housing space;
With
A spark plug in which the first exposed portion and the second exposed portion further protrude from the protruding portion. 　請求項１の点火プラグにおいて、
　前記第１の露出部は、
第１の棒先端
を有し、
　前記第２の露出部は、
第２の棒先端
を有する
点火プラグ。 The spark plug of claim 1.
The first exposed portion is
Having a first rod tip;
The second exposed portion is
A spark plug having a second rod tip. 　請求項１から請求項６までのいずれかの点火プラグにおいて、
　互いに絶縁される２個以上の前記浮遊電極が設けられる
点火プラグ。 The spark plug according to any one of claims 1 to 6,
A spark plug provided with two or more floating electrodes insulated from each other. 　点火装置であって、
　碍子、高圧電極、接地電極及び浮遊電極を備え、前記高圧電極が前記碍子の外部に露出する第１の露出部及び前記碍子に埋設される第１の被埋設部を備え、前記浮遊電極が前記碍子の外部に露出する第２の露出部及び前記碍子に埋設される第２の被埋設部を備え、前記接地電極が前記第１の露出部から相対的に遠く、前記第２の露出部が前記第１の露出部に相対的に近く、前記高圧電極と前記浮遊電極との間の静電容量が相対的に小さく、前記接地電極と前記浮遊電極との間の静電容量が相対的に大きい点火プラグと、
　前記高圧電極と前記接地電極との間にパルス電圧を印加するパルス電圧印加機構と、
を備える点火装置。 An ignition device,
An insulator, a high-voltage electrode, a ground electrode, and a floating electrode, the high-voltage electrode including a first exposed portion exposed to the outside of the insulator and a first embedded portion embedded in the insulator; A second exposed portion exposed to the outside of the insulator and a second embedded portion embedded in the insulator, wherein the ground electrode is relatively far from the first exposed portion, and the second exposed portion is The capacitance between the high-voltage electrode and the floating electrode is relatively small, and the capacitance between the ground electrode and the floating electrode is relatively close to the first exposed portion. With a large spark plug,
A pulse voltage application mechanism that applies a pulse voltage between the high-voltage electrode and the ground electrode;
An ignition device comprising: 　混合気に点火する方法であって、
　(a) 碍子、高圧電極、接地電極及び浮遊電極を備え、前記高圧電極が前記碍子の外部に露出する第１の露出部及び前記碍子に埋設される第１の被埋設部を備え、前記浮遊電極が前記碍子の外部に露出する第２の露出部及び前記碍子に埋設される第２の被埋設部を備え、前記接地電極が前記第１の露出部から相対的に遠く、前記第２の露出部が前記第１の露出部に相対的に近く、前記高圧電極と前記浮遊電極との間の静電容量が相対的に小さく、前記接地電極と前記浮遊電極との間の静電容量が相対的に大きい点火プラグを準備する工程と、
　(b) 前記高圧電極と前記接地電極との間にパルス電圧を印加し、前記第１の露出部と前記第２の露出部との間にストリーマ放電を発生させる工程と、
を備える混合気に点火する方法。 A method of igniting an air-fuel mixture,
(a) an insulator, a high-voltage electrode, a ground electrode, and a floating electrode, the high-voltage electrode including a first exposed portion that is exposed to the outside of the insulator and a first embedded portion that is embedded in the insulator; A second exposed portion where an electrode is exposed to the outside of the insulator and a second embedded portion embedded in the insulator; wherein the ground electrode is relatively far from the first exposed portion; An exposed portion is relatively close to the first exposed portion, a capacitance between the high voltage electrode and the floating electrode is relatively small, and a capacitance between the ground electrode and the floating electrode is Preparing a relatively large spark plug;
(b) applying a pulse voltage between the high-voltage electrode and the ground electrode to generate a streamer discharge between the first exposed portion and the second exposed portion;
A method of igniting an air-fuel mixture comprising: 　点火プラグであって、
　碍子と、
　前記碍子の外部に露出する第１の露出部を備える接地電極と、
　前記碍子に埋設される第１の被埋設部を備え、前記第１の露出部から相対的に遠い高圧電極と、
　前記碍子の外部に露出する第２の露出部及び前記碍子に埋設される第２の被埋設部を備え、前記第２の露出部が前記第１の露出部に相対的に近く、前記高圧電極との間に相対的に大きな静電容量を持ち、前記接地電極との間に相対的に小さな静電容量を持つ浮遊電極と、
を備える点火プラグ。 A spark plug,
With Reiko,
A ground electrode including a first exposed portion exposed to the outside of the insulator;
A first embedded portion embedded in the insulator; a high voltage electrode relatively far from the first exposed portion;
A second exposed portion exposed outside the insulator and a second embedded portion embedded in the insulator, wherein the second exposed portion is relatively close to the first exposed portion, and the high-voltage electrode A floating electrode having a relatively large capacitance between the ground electrode and a relatively small capacitance between the ground electrode,
With spark plug. 　請求項１０の点火プラグにおいて、
　前記第１の被埋設部は、
　第１の構造物
を備え、
　前記第２の被埋設部は、
　内部空間が形成された第２の構造物
を備え、
　前記碍子は、
　前記内部空間に充填され、前記第１の構造物が埋設される被充填部
を備える
点火プラグ。 The spark plug of claim 10.
The first embedded portion is
Comprising a first structure;
The second embedded portion is
A second structure in which an internal space is formed;
The eggplant is
A spark plug including a filling portion that is filled in the internal space and in which the first structure is embedded. 　請求項１１の点火プラグにおいて、
　前記第１の構造物は、棒形状部であり、
　前記第２の構造物は、前記棒形状部の周りを一周する管形状部である
点火プラグ。 The spark plug of claim 11.
The first structure is a rod-shaped portion,
The second structure is a spark plug that is a tube-shaped portion that goes around the rod-shaped portion. 　請求項１０の点火プラグにおいて、
　前記接地電極に収容空間が形成され、
　前記碍子は、
　前記収容空間の内部に中空保持される被中空保持部
を備える
点火プラグ。 The spark plug of claim 10.
A storage space is formed in the ground electrode,
The eggplant is
A spark plug including a hollow holding portion that is hollowly held inside the housing space. 　請求項１０の点火プラグにおいて、
　前記接地電極に収容空間が形成され、
　前記碍子は、
　前記収容空間に収容される被収容部
を備え、
　前記第２の露出部は、前記被収容部の外部に突出し、前記収容空間の外部に突出する
点火プラグ。 The spark plug of claim 10.
A storage space is formed in the ground electrode,
The eggplant is
A portion to be accommodated to be accommodated in the accommodation space;
The second exposed portion is a spark plug that protrudes outside the receiving portion and protrudes outside the receiving space. 　請求項１０の点火プラグにおいて、
　前記第２の露出部は、棒先端を有する
点火プラグ。 The spark plug of claim 10.
The second exposed portion is a spark plug having a rod tip. 　請求項１０から請求項１５までのいずれかの点火プラグにおいて、
　互いに絶縁される２個以上の前記浮遊電極が設けられる
点火プラグ。 The spark plug according to any one of claims 10 to 15,
A spark plug provided with two or more floating electrodes insulated from each other. 　点火装置であって、
　碍子、接地電極、高圧電極及び浮遊電極を備え、前記接地電極が前記碍子の外部に露出する第１の露出部を備え、前記高圧電極が前記碍子に埋設される第１の被埋設部を備え、前記浮遊電極が前記碍子の外部に露出する第２の露出部及び前記碍子に埋設される第２の被埋設部を備え、前記高圧電極が前記第１の露出部から相対的に遠く、前記第２の露出部が前記第１の露出部に相対的に近く、前記接地電極と前記浮遊電極との間の静電容量が相対的に小さく、前記高圧電極と前記浮遊電極との間の静電容量が相対的に大きい点火プラグと、
　前記高圧電極と前記接地電極との間にパルス電圧を印加するパルス電圧印加機構と、
を備える点火装置。 An ignition device,
An insulator, a ground electrode, a high voltage electrode, and a floating electrode are provided, the ground electrode includes a first exposed portion that is exposed to the outside of the insulator, and the high voltage electrode includes a first embedded portion that is embedded in the insulator. The floating electrode includes a second exposed portion that is exposed to the outside of the insulator and a second embedded portion that is embedded in the insulator, and the high-voltage electrode is relatively far from the first exposed portion, The second exposed portion is relatively close to the first exposed portion, the capacitance between the ground electrode and the floating electrode is relatively small, and the static electricity between the high-voltage electrode and the floating electrode is relatively small. A spark plug having a relatively large electric capacity;
A pulse voltage application mechanism that applies a pulse voltage between the high-voltage electrode and the ground electrode;
An ignition device comprising: 　混合気に点火する方法であって、
　(a) 碍子、接地電極、高圧電極及び浮遊電極を備え、前記接地電極が前記碍子の外部に露出する第１の露出部を備え、前記高圧電極が前記碍子に埋設される第１の被埋設部を備え、前記浮遊電極が前記碍子の外部に露出する第２の露出部及び前記碍子に埋設される第２の被埋設部を備え、前記高圧電極が前記第１の露出部から相対的に遠く、前記第２の露出部が前記第１の露出部に相対的に近く、前記接地電極と前記浮遊電極との間の静電容量が相対的に小さく、前記高圧電極と前記浮遊電極との間の静電容量が相対的に大きい点火プラグを準備する工程と、
　(b) 前記高圧電極と前記接地電極との間にパルス電圧を印加し、前記第１の露出部と前記第２の露出部との間にストリーマ放電を発生させる工程と、
を備える混合気に点火する方法。 A method of igniting an air-fuel mixture,
(a) a first embedded structure including an insulator, a ground electrode, a high-voltage electrode, and a floating electrode, the ground electrode including a first exposed portion exposed to the outside of the insulator, and the high-voltage electrode embedded in the insulator A second exposed portion where the floating electrode is exposed to the outside of the insulator and a second embedded portion embedded in the insulator, wherein the high-voltage electrode is relatively positioned relative to the first exposed portion. Distant, the second exposed portion is relatively close to the first exposed portion, the capacitance between the ground electrode and the floating electrode is relatively small, and the high-voltage electrode and the floating electrode Preparing a spark plug having a relatively large capacitance between,
(b) applying a pulse voltage between the high-voltage electrode and the ground electrode to generate a streamer discharge between the first exposed portion and the second exposed portion;
A method of igniting an air-fuel mixture comprising: 　点火プラグであって、
　碍子と、
　前記碍子の外部に露出する第１の露出部及び前記碍子に埋設される被埋設部を備える高圧電極と、
　前記第１の露出部から相対的に遠い接地電極と、
　前記碍子の外部に露出する第２の露出部を備え、前記第２の露出部が前記第１の露出部に相対的に近く、前記高圧電極との間に第１の静電容量を持ち、前記接地電極との間に第２の静電容量を持つ浮遊電極と、
　一方の端子が前記浮遊電極に電気的に接続され、他方の端子が前記接地電極に電気的に接続され、第３の静電容量を持ち、前記第２の静電容量と前記第３の静電容量との和が前記第１の静電容量より大きく、前記碍子に外付けされるキャパシタと、
を備える点火プラグ。 A spark plug,
With Reiko,
A high-voltage electrode including a first exposed portion exposed to the outside of the insulator and a buried portion embedded in the insulator;
A ground electrode relatively far from the first exposed portion;
A second exposed portion exposed to the outside of the insulator, the second exposed portion is relatively close to the first exposed portion, and has a first capacitance with the high-voltage electrode; A floating electrode having a second capacitance between the ground electrode and the ground electrode;
One terminal is electrically connected to the floating electrode, the other terminal is electrically connected to the ground electrode, has a third capacitance, and the second capacitance and the third electrostatic capacitance. A capacitor whose sum of capacitance is larger than the first capacitance and is externally attached to the insulator;
With spark plug.
PCT/JP2012/072895 2011-09-20 2012-09-07 Spark plug, ignition device and method for igniting air-fuel mixture Ceased WO2013042555A1 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017141293A1 (en) * 2016-02-15 2017-08-24 日本特殊陶業株式会社 Spark plug
JP2018139197A (en) * 2017-02-24 2018-09-06 日本特殊陶業株式会社 Spark plug

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5183538U (en) * 1974-12-26 1976-07-05
JPS625582A (en) * 1985-06-28 1987-01-12 株式会社日本自動車部品総合研究所 Spark plug
JPH0536463A (en) * 1991-07-30 1993-02-12 Ngk Spark Plug Co Ltd Spark plug

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5183538U (en) * 1974-12-26 1976-07-05
JPS625582A (en) * 1985-06-28 1987-01-12 株式会社日本自動車部品総合研究所 Spark plug
JPH0536463A (en) * 1991-07-30 1993-02-12 Ngk Spark Plug Co Ltd Spark plug

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017141293A1 (en) * 2016-02-15 2017-08-24 日本特殊陶業株式会社 Spark plug
JP2017147020A (en) * 2016-02-15 2017-08-24 日本特殊陶業株式会社 Spark plug
JP2018139197A (en) * 2017-02-24 2018-09-06 日本特殊陶業株式会社 Spark plug

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