JP7275825B2 - Ignition coil for internal combustion engine - Google Patents

Description

The present invention relates to ignition coils for internal combustion engines.

2. Description of the Related Art Some ignition coils for internal combustion engines have a central core and an outer core that form a magnetic circuit and are formed by laminating a plurality of plate-shaped magnetic steel plates. Then, there is an ignition coil in which a magnet that gives a magnetic flux in the opposite direction to the magnetic flux generated in the magnetic circuit by energization of the primary coil is arranged between the central core and the outer core in the magnetic circuit. As a result, the amount of change in the magnetic flux when the power supply to the primary coil is cut off increases, and the input energy increases, thereby increasing the voltage induced in the secondary coil.

However, disposing a thin magnet body between the central core and the peripheral core in a state where the central core and the peripheral core are assembled may cause damage to the magnet body.

Therefore, in the ignition coil disclosed in Patent Document 1, the tip of the plate-like magnet body is tapered to facilitate installation and prevent damage to the magnet body.

JP-A-2000-331853

However, the ignition coil described in Patent Document 1 has the following problems.
Even if the magnet body has a tapered surface, it may get caught on the step between the magnetic steel plates on the end face of the central core. As a result, it is not always possible to prevent damage such as chipping or cracking of the magnet body when the magnet body is assembled.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ignition coil for an internal combustion engine that can prevent damage to a magnet during assembly.

One aspect of the present invention comprises a primary coil (5) and a secondary coil (6) magnetically coupled to each other;
a central core (2) formed by laminating a plurality of magnetic steel plates (13) and inserted through the inner sides of the primary coil and the secondary coil;
A peripheral core (3) that forms a magnetic circuit perpendicular to the stacking direction of the magnetic steel plates together with the central core and is disposed outside the primary coil and the secondary coil;
a magnet body (4) disposed between the central core and the outer core in the magnetic circuit;
A groove portion (211) extending over the entire stacking direction of the magnetic steel plates is formed in a part of the center side facing surface (212), which is the surface of the central core facing the magnet body. is in an ignition coil (1) for an internal combustion engine, covered by a coating resin (213).

In the ignition coil for an internal combustion engine, the center side facing surface is covered with a coating resin. Therefore, it is possible to prevent the step caused by the edge of the magnetic steel plate from being exposed to the magnet body side on the center side facing surface.

Further, a groove is formed in a part of the center-side facing surface of the central core that faces the magnet body. Therefore, in the manufacturing process of the ignition coil, the resin can be supplied to the center side facing surface through the groove. Therefore, it is possible to easily obtain a configuration in which the center-side facing surface is covered with the coating resin. As a result, damage to the magnet body during assembly can be prevented.

As described above, according to the above aspect, it is possible to provide an ignition coil for an internal combustion engine that can prevent the magnet from being damaged during assembly.
It should be noted that the symbols in parentheses described in the claims and the means for solving the problems indicate the corresponding relationship with the specific means described in the embodiments described later, and limit the technical scope of the present invention. not a thing

1 is a cross-sectional view of an ignition coil for an internal combustion engine in Embodiment 1; FIG. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1; FIG. 4 is a cross-sectional view of the unit in which the central core and the outer core are assembled, before the magnet body is assembled. FIG. 4 is a cross-sectional view of the unit in which the central core and the outer core are assembled, after the magnet bodies are assembled. 2 is a plan view of the central core viewed from the Z direction in Embodiment 1. FIG. 2 is a plan view of the central core viewed from the front side in the X direction in Embodiment 1. FIG. FIG. 2 is a cross-sectional view of a mold for insert-molding the primary spool together with the central core in the first embodiment, viewed from the Y direction; A cross-sectional view taken along line VIII-VIII in FIG. A cross-sectional view taken along line IX-IX in FIG. FIG. 8 is an enlarged cross-sectional view near the center side facing surface in FIG. 7 ; 2 is a plan view of the primary spool viewed from the Y direction in Embodiment 1. FIG. 2 is a plan view of the primary spool viewed from the X direction in Embodiment 1. FIG. A cross-sectional view taken along line XIII-XIII in FIG. FIG. 4 is an enlarged cross-sectional view of the vicinity of the groove portion of the central core whose center-side facing surface is not covered with the coating resin in the first embodiment; FIG. 4 is an enlarged cross-sectional view of the vicinity of the groove portion of the center core whose center-side facing surface is covered with a coating resin according to Embodiment 1;

(Embodiment 1)
An embodiment of an ignition coil 1 for an internal combustion engine will be described with reference to FIGS. 1 to 6. FIG.
An ignition coil 1 for an internal combustion engine according to the present embodiment, as shown in FIG. have. The central core 2 is formed by laminating a plurality of magnetic steel plates 13 . Also, the central core 2 is arranged to pass through the inner sides of the primary coil 5 and the secondary coil 6 . The outer core 3 forms a magnetic circuit perpendicular to the stacking direction of the magnetic steel plates 13 together with the central core 2 . Further, the outer core 3 is arranged outside the primary coil 5 and the secondary coil 6 . The magnet 4 is arranged between the central core 2 and the outer core 3 in the magnetic circuit. As shown in FIG. 6, a groove 211 is formed over the magnetic steel plates 13 in the stacking direction on a portion of the center-side facing surface 212 of the central core 2 that faces the magnet body 4 . The center-side facing surface 212 is covered with a coating resin 213 .

As shown in FIGS. 1 and 2, a primary spool 51 around which a primary coil 5 is wound is provided on the outer peripheral surface of the central core 2 . The coating resin 213 is integrally formed with the primary spool 51 as shown in FIG.

The primary coil 5 is formed by winding a primary winding around the outer peripheral surface of the primary spool 51 . The secondary coil 6 is formed by winding a secondary winding around the outer peripheral surface of the secondary spool 61 . The winding axis of the secondary coil 6 is coaxial with the winding axis of the primary coil 5 . Also, the primary coil 5 is arranged on the outer peripheral side of the central core 2 . The secondary coil 6 is arranged on the outer peripheral side of the primary coil 5 . The winding axes of the primary coil 5 and the secondary coil 6 and the central axis C of the central core 2 are coaxial. Note that the axial direction parallel to the central axis C of the central core 2 is also referred to as the X direction as appropriate. Further, the direction perpendicular to the X direction, which is the lamination direction of the plurality of magnetic steel plates 13 forming the central core 2, will also be referred to as the Z direction as appropriate. A direction orthogonal to both the X direction and the Z direction is also called the Y direction as appropriate. Also, in the X direction, the side where the connector portion 52 protrudes is called the front side, and the opposite side is called the rear side. Also, in the Z direction, the side on which the high-voltage tower section 72 is provided is called the lower side, and the opposite side is called the upper side.

As shown in FIGS. 1 and 2, the case 7 accommodates the primary coil 5, the secondary coil 6, the central core 2, the outer core 3, and other parts inside. The case 7 is filled with a mold resin 12 together with these components. Mold resin 12 is, for example, epoxy resin.

As shown in FIG. 2, the case 7 is fitted with a connector portion 52 for connecting the ignition coil 1 to the outside. The connector portion 52 protrudes forward in the X direction. The connector portion 52 has connector terminals 521 inside. For example, when the ignition coil 1 is mounted on a vehicle, the connector terminal 521 is connected to a control device (not shown). The connector terminal 521 is also connected to the terminal of the igniter 11 .

The igniter 11 is positioned between the outer core 3 and the connector portion 52 as shown in FIG. The igniter 11 energizes and cuts off the primary coil 5 according to an ignition signal determined by the control device. The igniter 11 is housed in the case 7 and entirely buried in the mold resin 12 .

The high voltage tower section 72 is formed below the case 7 as shown in FIG. The high voltage tower portion 72 has a tubular shape. The high voltage tower portion 72 is formed to protrude downward. A conductive terminal 721 is provided on the high voltage tower section 72 . Conductive terminal 721 is connected to secondary coil 6 via high voltage terminal 62 . When the igniter 11 cuts off the energization of the primary coil 5, a high voltage is generated in the secondary coil 6 by electromagnetic induction. The generated high voltage generates discharge sparks in the discharge gap of an ignition plug (not shown) that is electrically connected to the secondary coil 6 via the conducting terminal 721 . The generated discharge spark ignites the air-fuel mixture in the internal combustion engine.

The magnet body 4 is arranged between the central core 2 and the outer peripheral core 3 in the magnetic circuit formed by the central core 2 and the outer peripheral core 3 . That is, as shown in FIG. 1, the magnet body 4 is arranged so as to face both the central facing surface 212 that is the front surface of the central core 2 and the outer circumferential facing surface 31 that is located on the inner peripheral side of the outer peripheral core 3 . is distributed. The magnet body 4 is assembled so as to cover the entire center-side facing surface 212 of the central core 2 . The magnet body 4 is, for example, a permanent magnet such as a neodymium magnet or a rare earth cobalt magnet.

The magnets 4 are arranged so that the direction of the magnetic field generated by the magnets 4 is opposite to the direction of the magnetic field generated in the central core 2 when the primary coil 5 is energized. The magnet 4 then magnetically biases the central core 2 so as to increase the input energy of the ignition coil 1 . That is, by increasing the amount of change in the magnetic flux when the primary coil 5 is de-energized, the input energy is increased and the voltage induced in the secondary coil 6 is increased.

Moreover, the magnet body 4 has a plate-like shape. As shown in FIG. 2, when the ignition coil 1 is viewed from the Y direction, the magnet body 4 has a size in the Z direction approximately equal to the width of the center core 2 in the Z direction. Also, the size of the magnet 4 in the Z direction is smaller than the width of the outer core 3 in the Z direction.

The magnet 4 is assembled by driving it in the Z direction with respect to the unit in which the central core 2 and the outer core 3 are assembled before being incorporated into the case 7 . As shown in FIG. 3, the magnet 4 is assembled to the unit in the Z direction from the lower side to the upper side when the unit is assembled in the ignition coil 1 . That is, the magnet 4 is assembled to the unit along the direction of the arrow shown in FIG. Also, the magnet body 4 is inserted along the stacking direction of the magnetic steel plates 13 of the central core 2 . 4, the magnet body 4 is inserted between the central facing surface 212 of the central core 2 and the outer facing surface 31 of the outer core 3. As shown in FIG.

As shown in FIG. 1, the outer core 3 has a rectangular annular shape when viewed from the Z direction. The outer core 3 forms a closed magnetic circuit together with the central core 2 .

The outer core 3 is formed by laminating a plurality of magnetic steel plates 14 . The lamination direction of the magnetic steel plates 14 of the outer core 3 is the same as the lamination direction of the magnetic steel plates 13 of the central core 2 . That is, the magnetic steel plates 14 of the outer core 3 are laminated in the Z direction. An outer facing surface 31 of the outer core 3 facing the magnet 4 is covered with an insulating film 32 .

The plurality of magnetic steel plates 13 and 14 forming the central core 2 and the outer core 3 are fixed to each other in the stacking direction by crimping the crimped portions formed on the respective magnetic steel plates 13 and 14 . Note that the magnetic steel plates 13 and 14 may be fixed to each other by laser welding or adhesion.

The insulating film 32 covers the front outer peripheral surface of the outer core 3 . As shown in FIGS. 1 and 2, the insulating film 32 covers the entire outer peripheral facing surface 31 . The insulating film 32 may be wound around the outer peripheral surface on the front side of the outer core 3 by one or more turns. The insulating film 32 is, for example, an insulating tape.

As shown in FIGS. 1 and 5, the central core 2 has a flange portion 21 protruding in the width direction, which is the Y direction perpendicular to both the stacking direction and the axial direction. The center core 2 has a center side facing surface 212 on the collar portion 21 .

The central core 2 also has a core body portion 22 arranged inside the primary coil 5 . The collar portion 21 protrudes in the Y direction on the front side of the core body portion 22 . When viewed from the Z direction, the width of the flange 21 in the X direction decreases in the direction away from the central axis C of the central core 2 and in both Y directions. The central core 2 has a T-shape as a whole.

As shown in FIG. 1, a groove 211 is arranged on the central facing surface 212 at a position through which the central axis C of the central core 2 passes. That is, the central axis C passes through the groove portion 211 . Also, the central axis C passes through the center of the groove portion 211 in the Y direction. Also, the central axis C passes through the center of the groove portion 211 in the Z direction.

The width of the groove portion 211 in the Y direction is smaller than the width of the core body portion 22 in the Y direction, as shown in FIG. Also, the center-side facing surfaces 212 located on both sides in the Y direction with the groove 211 interposed therebetween are on the same plane. In addition, the center-side facing surface 212 as a whole is a plane perpendicular to the X direction. However, the center-side facing surface 212 is formed with unevenness due to a slight deviation between the edges of the plurality of magnetic steel plates 13 and the shape of the edges themselves.

Next, a method for manufacturing the primary spool 51 will be described.
The primary spool 51 is insert molded with the central core 2 inside. The primary spool 51 is made of insulating resin.

In manufacturing the primary spool 51, as shown in FIGS. 7 to 9, the center core 2 is preliminarily placed inside a mold composed of a fixed mold M1, a movable mold M2, and slide molds M3 and M4. place in position. As shown in FIG. 7, the central core 2 is fixed by a fixed die M1 and a movable die M2 so as to be sandwiched in the Z direction. Also, as shown in FIG. 8, the central core 2 is fixed so as to be sandwiched in the X direction by two slide dies M3 and M4. The primary spool 51 and the central core 2 are integrally formed by pouring molten resin into a cavity 510 formed in the mold.

An end portion of the magnetic steel plate 13 forming the central core 2 has a burr portion 131 formed by press working. That is, when the magnetic steel plate 13 is formed, the burr portion 131 is formed by pulling a part of the steel plate so as to be torn off when the steel plate is sheared by a die for press working. After that, a plurality of magnetic steel plates 13 are laminated and pressed, so that the burr portion 131 protrudes outward in the spreading direction of the magnetic steel plates 13 . As a result, the burr portion 131 protrudes from the edge of the central core 2 as shown in FIG. Therefore, unevenness is formed on the edge of the central core 2 .

The center-side facing surface 212 of the central core 2 is in contact with the mold surface of the slide mold M3, as shown in FIG. Further, when a part of the central facing surface 212 shown in FIG. 7 is enlarged, as shown in FIG. It is in contact with the mold surface. An end space 130 surrounded by the end including the burr portion 131 of the laminated magnetic steel plates 13 and the mold surface of the slide mold M3 is formed. The end space 130 is formed along the Y direction. The end space 130 communicates with the groove 211 at one end in the Y direction.

In the process of manufacturing the primary spool 51 , part of the melted resin flows into the grooves 211 formed in the center-side facing surface 212 of the central core 2 . That is, as shown in FIGS. 7 and 9, the melted resin flows into the groove space 214 continuous in the Z direction formed between the groove 211 and the mold surface of the slide mold M3 facing it. As shown in FIG. 10, the resin that has flowed into the groove space 214 flows from the groove space 214 toward both sides in the Y direction into the end space 130 . Then, the end space 130 is filled with the inflowing resin.

After the resin poured into the cavity 510 is solidified, the primary spool 51 is removed from the mold. At this time, the movable die M2 moves away from the primary spool 51 in the Z direction. Also, the two slide dies M3, M4 move away from the primary spool 51 in the X direction. Then, the primary spool 51 is obtained by removing it from the fixed mold M1.

The molded primary spool 51 is integrally formed with the central core 2 as shown in FIG. As shown in FIG. 12 , when the primary spool 51 is viewed from the front side in the X direction, the entire center-side facing surface 212 of the center core 2 is covered with the coating resin 213 . Thereby, the center side facing surface 212 is flattened. That is, even if there is a step formed by the edges of the plurality of magnetic steel plates 13 on the center-side facing surface 212 , the center-side facing surface 212 is flattened by being covered with the coating resin 213 . Also, the coating resin 213 is formed integrally with the primary spool 51 .

The resin of the groove 211 of the center core 2 is also integrated with the primary spool 51 as shown in FIG. That is, the groove portion 211 is filled with resin, and the resin in the groove portion 211 is also part of the coating resin 213 .

More specifically, as shown in FIG. 14, the end portion of the pressed magnetic steel plate 13 is exposed on the central facing surface 212 of the central core 2 before the coating resin 213 is formed. Further, as described above, the end portion of the magnetic steel plate 13 has the burr portion 131 . Since the center-side facing surface 212 is a laminated surface in which the magnetic steel plates 13 are laminated, it has a plurality of steps.

By insert-molding the primary spool 51 together with the center core 2 as described above, the coating resin 213 is formed on the center-side facing surface 212 . Therefore, the burrs 131 and the grooves 211 of the central facing surface 212 are covered with the coating resin 213 as shown in FIG. The center-side facing surface 212 is flattened by the coating resin 213 .

Next, the effects of this embodiment will be described.
In the ignition coil 1 for an internal combustion engine of this embodiment, the center-side facing surface 212 is covered with a coating resin 213 . Therefore, in the center-side facing surface 212 , it is possible to prevent the step caused by the edge of the magnetic steel plate 13 from being exposed to the magnet body 4 side.

A groove portion 211 is formed in a part of the central facing surface 212 of the central core 2 facing the magnet body 4 . Therefore, in the manufacturing process of the ignition coil 1 , resin can be supplied to the center-side facing surface 212 through the groove 211 . Therefore, a configuration in which the center-side facing surface 212 is covered with the coating resin 213 can be easily obtained. As a result, damage to the magnet body 4 during assembly can be prevented.

Also, the coating resin 213 formed on the center-side facing surface 212 is formed integrally with the primary spool 51 . Therefore, high strength and durability can be obtained compared to the case where only the coating resin 213 is formed.

Also, the central core 2 and the outer core 3 constitute a magnetic circuit. The magnetic flux density is small near the center of the central core 2 in the Y direction and tends to be large outside. Further, the groove portion 211 is arranged at a position through which the central axis C of the central core 2 passes. That is, the groove portion 211 is arranged near the center where the magnetic flux density is low. Further, the groove portion 211 is not formed outside the central core 2 . Therefore, it is possible to prevent damage to the magnet body 4 during assembly without degrading the performance of the ignition coil 1 .

In addition, an outer facing surface 31 of the outer core 3 is covered with an insulating film 32 . Therefore, it is possible to prevent the step caused by the edge of the magnetic steel plate 14 from being exposed to the magnet body 4 side in the outer peripheral side facing surface 31 . As a result, damage to the magnet body 4 during assembly can be prevented. In addition, since the outer core 3 is covered with the insulating film 32, leakage of voltage from the outer core 3 to the igniter 11 adjacent to the outer core 3 can be suppressed.

Further, the center core 2 has a flange portion 21 protruding in the Y direction. The center core 2 has a center-side facing surface 212 on the collar portion 21 . Therefore, even if the groove portion 211 is formed in the center-side facing surface 212 , it is easy to sufficiently secure the magnetic path from the central core 2 to the outer peripheral core 3 . As a result, it is possible to prevent damage to the magnet body 4 during assembly without reducing the performance of the ignition coil 1 .

As described above, according to this embodiment, it is possible to provide the ignition coil 1 for an internal combustion engine that can prevent damage to the magnet body 4 during assembly.

In the ignition coil 1 of the above-described embodiment, one groove portion 211 is formed in a portion of the center-side facing surface 212 . However, two or more grooves 211 may be formed in a part of the center-side facing surface 212 .

Further, in the ignition coil 1 of the above embodiment, the shape of the groove portion 211 is a substantially rectangular shape in which the width in the Y direction is larger than the width in the X direction when viewed from the Z direction. However, the shape of the groove portion 211 can also be such that the width in the X direction is greater than or equal to the width in the Y direction. Also, the shape of the groove portion 211 can be substantially triangular or substantially semicircular.

The present invention is not limited to the above embodiments, and can be applied to various embodiments without departing from the scope of the invention.

REFERENCE SIGNS LIST 1 ignition coil 13 magnetic steel plate 2 center core 211 groove 212 center side facing surface 213 coating resin 3 outer core 4 magnet body 5 primary coil 6 secondary coil

Claims (5)

a primary coil (5) and a secondary coil (6) magnetically coupled to each other;
a central core (2) formed by laminating a plurality of magnetic steel plates (13) and inserted through the inner sides of the primary coil and the secondary coil;
A peripheral core (3) that forms a magnetic circuit perpendicular to the stacking direction of the magnetic steel plates together with the central core and is disposed outside the primary coil and the secondary coil;
a magnet body (4) disposed between the central core and the outer core in the magnetic circuit;
A groove portion (211) extending over the entire stacking direction of the magnetic steel plates is formed in a part of the center side facing surface (212), which is the surface of the central core facing the magnet body. is an ignition coil (1) for an internal combustion engine, covered with a coating resin (213). 2. The method according to claim 1, wherein a primary spool (51) around which the primary coil is wound is provided on the outer peripheral surface of the central core, and the coating resin is integrally formed with the primary spool. An ignition coil for an internal combustion engine as described. 3. The ignition coil for an internal combustion engine according to claim 1, wherein said groove portion is arranged at a position through which a central axis (C) of said central core passes. The outer core is formed by laminating a plurality of magnetic steel plates (14), and the lamination direction of the magnetic steel plates in the outer core is the same as the lamination direction of the magnetic steel plates in the central core. The ignition coil for an internal combustion engine according to any one of claims 1 to 3, wherein an outer peripheral side facing surface (31) facing the magnet body is covered with an insulating film (32). 5. The central core according to any one of claims 1 to 4, wherein the central core has a flange (21) protruding in a width direction perpendicular to both the stacking direction and the axial direction, and the flange has the center side facing surface. 11. An ignition coil for an internal combustion engine according to Claim 1.

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