US2461293A - Ignition circuit - Google Patents

Description

Feb. 8, 1949. R. J. MILLER 2,461,293 v IGNITION CIRCUIT Filed June 21, 1943 s 5 Sheets-Sheet l A I:.:: I V Ollllllllli yi 60 INVENTOR.

J/WLLE'E Feb. 8, 1949. R. J. MILLER IGNITION CIRCUIT 5 Sheets-Sheet 2 Filed June 21, 1843 iv l hu l l l hqle l INVENTOR.

QTTOE/Vfk R. J. MILLER IGNITION CIRCUIT Feb. 8, 1949 5 Sheets-Sheet 3 Filed June 21-. 1943 INVENTOR. J/V/LLE/E fiarnozva Feb. 8, 1949. M L 2,461,293

IGNITION CIRCUIT Filed June 21, 1943 5 Sheets-Sheet 4 INVENTOR. EQVMO/Vfl u Ma (.58

Feb. 8, 1949. R. J. MILLER IGNITION CIRCUIT 5 Sheets-Sheet 5 Filed June 21, 1943 5/ INVENTOR. EQVMO/VD 1 M44545 .4

INN 4A II/ Y Patented Feb. 8, 1949 UNITED STATES PATENT OFFICE IGNITION CIRCUIT Raymond J. Miller, Detroit, Mich.

Application June 21, 1943, Serial No. 491,584

3 Claims.

This invention relates to engines, and more particularly to improved ignition systems for engines.

In conventional ignition systems, the voltage is stepped up and is transmitted through single high tension leads to the spark plugs to fire the combustible charge in the cylinder of the engine. Single electrode spark plugs are employed, and the circuit is completed by enclosing the entire ignition system in metallic covers, or by utihzing the engine as a ground to complete the circuit. The entire engine and vehicle thus becomes a part of the ignition circuit and acts as a variable capacitor.

In accordance with conventional practice, a

single high tension coil is used for each engine. In multi-cylinder engines, this coil is frequently over-taxed because the reluctance will not permit the coil to completely collapse before the next impulse is imposed on it to provide the necessary high voltage spark to fire the next cylinder when the engine is operating at high speed. In certain high speed engines it has been necessary to employ two or more high tension coils per engine to prevent over-taxing the coils.

Considerable current from the high tension coils is lost before reaching the spark plugs through leakage from the high tension wires connected to the spark plugs. The efiiciency of ignition systems now'in use is therefore considerably below that desired.

In ignition systems as presently employed, undesirable signals are emitted whenever the en gine is running. These undesirable signals are emitted from:

1. The sparking of high tension current jumping from the rotating distributor arm to the successive distribution points.

2. The sparking at the spark plug electrodes.

3. The leakage from the high tension wires leading from the distributor to the spark plugs.

In military vehicles, the enemy can establish listening stations and readily pick up these undesirable signals emitted from the ignition system. The exact location of a vehicle or a convoy of vehicles can thus readily be ascertained by triangulation from spaced listening stations. Accurate gun fire can then be brought to bear on the vehicle or convoy of vehicles.

These undesirable signals emanating from the ignition system interfere with radio communication, both sending and receiving, and cause distortion of the images in the operation of television sending and receiving apparatus.

Efforts have been made to overcome these bjectionable features by using suppressors hooked within the circuits; by the use of shielding surrounding the wires and electrical units, and by bonding the component parts of the vehicle together to maintain good electrical contacts between all parts of the vehicle. These efforts have not been very successful because of the expense and time required in their installation and the difliculty of maintaining them in proper working condition.

An object of this invention is to provide a closed circuit ignition system wherein the above enumerated disadvantages are eliminated.

A further object of the invention resides in the provision of an improved ignition system wherein low voltage current is transmitted by a distributor to a compact transformer associated with each spark plug of the engine.

Another object is to provide an ignition system for an engine wherein dual electrode spark plugs insulated from the engine are supplied by high voltage circuits, each of which is completely contained within its associated spark plug.

Still a further object of the invention is to provide a distributor to induce low voltage current in such a manner that a spark gap capable of transmitting undesirable signals is not present.

Yet another object resides in the provision of a closed circuit ignition system wherein low voltage current is induced and is transmitted through low tension wires to small transformers positioned on dual electrode spark plugs insulated from the engine.

A further object is to provide an ignition system wherein transformers having primary and secondary windings wound in a bell shaped manner extend down over the body portions of dual electrode spark plugs to produce directed magnetic fields to provide controlled electric sparks at the electrodes of the plugs, and produce a blow-out condition at the spark gap to provide sharper more controlled points of ignition.

Another object of the invention resides in the provision of an ignition system wherein it is unnecessary to employ continuous shielding, bonding or suppressors to prevent the transmission of undesirable signals capable of indicating the location of the vehicle and interfering with radio or television transmission or reception.

Other objects and advantages of this invention will be apparent from the following detailed description considered in connection with the accompanying drawings, submitted for purposes of illustration only and not intended to define the scope of the invention, reference being had for that purpose to the subjoined claims.

In the drawings wherein similar reference characters refer to similar parts throughout the sev eral views:

Fig. 1 is a diagrammatic view illustrating a form of the invention wherein a magneto is employed as a source of electric current for a closed circuit ignition system.

Fig. 2 is a sectional view of one illustrative form of magneto mechanism taken substantially on the line 22 of Fig. 3 looking in the direction of the arrows.

Fig. 3 is a sectional view taken substantially on the line 33 of Fig. 2 looking in the direction of the arrows.

Fig. 4 is a sectional view taken substantially on the line 4-4 of Fig. 3 looking in the direc-- tion of the arrows, and showing an induction current having a multiple core member.

Fig. 5 is a view similar to Fig. 4 showing an induction coil having a single core member.

Fig. 6 is a sectional view taken substantially on the line 5-4; of Fig. 3 looking in the direction of the arrows, and showing the construction of the pole pieces of the magnet. V

Fig. '7 is an enlarged sectional View illustrating the dual electrode spark plug for a transformer associated therewith.

Fig. 8 is a bottom plan View of the spark plug illustrated in Fig. 7, taken substantially on the line 8- 8 of Fig. '7 looking in the direction of the arrows.

Fig. 9 is a fragmentary sectional view illustrating the manner in which wires may be connected to the transformers illustrated in Fig. '7.

Fig. 10 is a longitudinal sectional view of modified form or dual electrode spark plug.

Fig. 11 is a diagrammatic view illustrating a modified form of closed circuit ignition system wherein a battery is employed as a source of electric current.

Fig.- 12 is a vertical view illustrating a form of the distributor mechanism for use in the circuit illustrated in Fig. 11, and taken substantially on the line 12-52 of Fig. 13 looking in the direction of the arrows.

Fig. 13 is a sectional View taken substantially on the line l3--l3 of Fig. 12 looking in the direction of the arrows.

14 is a fragmentary Vertical sectional view of a still further modified form of the invention.

Fig. 15 is a fragmentary sectional View taken substantially on the line ill-45 of Fig. l i looking in the direction or the arrows.

Fig. 16 is a fragmentary sectional view illustrating one form of a connector.

Fig. 17 is a View similar to Fig. 16 showing a modified form of a connector.

Fig. 18 is a fragmentary sectional View illustrating a still further modified form of the invention.

g. 19 is a longitudinal sectional view illustrating a modified form of dual electrode spark lu D Fig. 20 is a fragmentary sectional view illus' trating a casing adapted to surround a portion of a' dual electrode spark plug, to protect itagainst the entrance of moisture.

Fig. 21 is a fragmentary sectional view illustrating an adjustable resistor member adapted to be interposed between an electrode of the spark plug and a source of electric current.

Fig. 22 is a view similar to Fig..21 illustrating a modifiediform of resistor member.

. Fig. 23 is a longitudinal sectional view illustrati ing a further modified form of dual electrode spark plug.

Fig. 24 is a sectional View taken substantially on the line 24-24 of Fig. 23, looking in the direction of the arrows.

Before explaining in detail the present invention it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Figure l is a diagrammatic view illustrating the circuit ignition system for a six cylinder internal combustion engine. A highly concentrated magnetic field type permanent magnet as is carried by a rotor arm l2 driven by a shaft is geared or otherwise suitably connected to the engine.

The magnet 18 has suitable pole pieces i6 and 58 adapted to rotate with reference to spaced induction coils 20, 22, 24, 26, 28 36. As the pole pieces of the magnet sweep past these induction coils, electric current is induced therein. The current thus induced is directed through wires 32 and as to opposite ends of primary coils 36 mounted on spark plugs ll), 42, 44, $5, 48 and Ell projecting into the cylinders of the engine.

As illustrated in Figs. 1 and 7 opposite ends of the primary coils 36 are connected to opposite ends of the induction coils 20, 22, 2%, 26, 28 and 3% respectively. Secondary coils 52 are preferably concentrically mounted on the primary coils 3%. Opposite ends of the secondary coils 52 are connected to spaced electrodes 54 and 5t of the spark plugs 49, 42, (.4, 45, 4S and 53 positioned within the cylinders of the engine.

Current is thus generated by movement of the magnet l0 relative to the induction coils 2Q, 22, 24, 25, 28 and 3B. This generated current is transmitted to the primary coil 36 to energize the secondary coil 52 by induction. The secondary coil 52 amplifies the charge and it is discharged in the engine cylinders between the electrodes 54 and 55 of the spark plugs.

In conventional ignition circuits a spark is impressed between a central electrode of the spark plug and an outer electrode secured to the shell of the spark plug threaded into the cylinder of the engine. The electric current to develop the spark is sup-plied by a battery or a magneto having one terminal connected or grounded to the frame of the vehicle or to the body of the engine. The other terminal of the battery or magneto is connected through suitable cont enser coils and distributors with the central electrode of the spark plug. When the spark is induced between the electrode of the spark plug, the electric circuit is thus completed to the battery or magneto through the frame of the vehicle or the body of the engine. The potential of current is therefore raised throughout the vehicle each time a spark plug is fired.

In my system a closed electric circuit is formed between the induction coils 2D, 22, 2 a, 26, 28 and 38 and therein associated primary coils 36 operably connected thereto through the wires 32 and 34. The potential of the current developed by the magnet ill or the electric coil substituted therefor is very low and will have negligible effect insofar as raising the potential of the current throughout the vehicle is concerned. A confined circuit is formed between the secondary coils 52 and the electrodes 54 and 56 of their associated spark plugs 40, 42, 44, 46, 48 and 50 when the secondary coils are fired by current induced by their associated primary coils. The current induced to fire the spark in the plugs will follow the path of least resistance. Since the outer electrode 56 is insulated from the shell or body of the spark plu and thus from the engine, the spark will be induced between the electrodes 54 and 56 and virtually no current will flow from the outer electrode 56 to the shell of the plug. The potential of the current throughout the vehicle is therefore not raised to any material extent.

, Moreover, as each high tension circuit is selfcontained in its respective spark plug, and as each plug has its own metallic casing, there is no possibility of the escape of electromagnetic emanations of radio frequencies; hence a radioshielding effect is inherent in the disclosed structure, yet Without the necessity of enclosing the entire ignition system in a continuous metallic covering, and without the provision of any shielding 'whatever for the low tension leads 32, 34, or the coils 20, 22, 24, 26, 28 and 30.

Referring now to Figs. 2 to '7 for more details of the mechanism, it will be noted that the induction coils 20, 22, 24, 26, 28 and 30 are mounted in a casing 58 surrounding the shaft I4. The wires 32 and 34 from opposite ends of the induction coils are directed through the walls of the casing 58 by means of suitable connectors 60. The wires 32 and 34 from the induction coils to the primary coils 36 are preferably braided to prevent the formation of line induction developed when wires run parallel to each other for a considerable distance.

Assuming counter-clockwise rotation of the magnet I as viewed in Fig. 3 and illustrated by the arrow 62, the induction coils 26, 22, 24, 26, 28 and 30 should be successively connected by the wires 32 and 34 to the coils associated with the spark plugs 40, 42, 44, 46, 48 and 50 in thedesired firing order of the cylinders of the engine. For example if the desired firing order of a six cylinder engine were 1-5-2-4-3-6, the coils 20, 22, 24, 26, 28 and 30 should be connected to the coils of the spark plugs 40, 42, 44, 46, 48 and 50 to fire the plugs in the desired order as the magnet I0 rotates.

v Any suitable mean may be provided to vary the time of-induoing the spark between the electrodes 54 and 56 of the spark plugs with reference to the position of the piston in the cylinder of the engine. One desirable form of control means comprises mounting the arm I2 on a plate 64 carried by the shaft I4 to have limited to rotational movement therewith. Yielding means such as a spring 66 may be provided to maintain the arm I2 in a retarded position. A centrifugally actuated member 68 having a weight 16 may be pivotally mounted on the plate 64 at I2. The member 68 may be provided with a hook I4 to engage an arm I6 carried by the arm I2 to oscillate the arm [2 in the direction of the arrow 62 as the speed of rotation increases to advance the spark or the time of inducing the spark between the electrodes 54 and '6 with reference to the position of the piston in the cylinder. Suitable stops I8 and 80 carried by the plate 64 may be provided to limit the movement of the centrifugally actuated member 68.

The induction coils 20, 22, 24, 26, 28 and 30 are preferably formed with a relatively large number of wires 82 resulting from a high number of turns about a core 84 to develop the desired current as the magnet I0 is moved past the coils.

The core 84 may be supported in any suitable insulating material 86, and the wires 82 may be wrapped about the core 84 and insulating material 86, and be maintained in position by means of suitable guides 88 having longitudinally extending flanges 96. Suitable supporting brackets 92 may engage the flanges to secure the coils in position within the casing 58.

The core 84 is preferably formed of a plurality of core pieces 94 to provide a multiple current surge and cause a repetition of firing in the cylinder of the engine. Where the core pieces 86 are formed of closely spaced laminated strips, a stronger more highly concentrated magnetic field will be produced. Greater possibility of firing the charge in the cylinder is thus insured.

For more economical installations where high performance is not essential a single \core member 96 as illustrated in Fig. 5 may be employed rather than the multiple core pieces 94 as illus trated in Figs. 3 and 4. It will be understood that where a single core member 96 is thus used, a single spark will be induced in the cylinder of the engine with the possibility of the back E. M. F. firing again if the suppression of the spark is not too great, rather than the multiple spark developed where multiple cores are employed.

The permanent magnet I0 is preferably formed of laminations 98 as illustrated in Fig. 6 to induce higher current as the magnet passes the induction coils. It will of course be understood that the magnet I0 and the core pieces 84 of the induction coils may be formed of sintered powdered or solid metal if desired.

One desirable form of dual electrode spark plug having the primary and secondary coils mounted thereon is illustrated in detail in Figs. 7 and.8. The spark plug 40 comprises a base member I00 having threads I02 whereby the plug may be secured in the combustion chamber of an engine, and a wrench receiving portion I04 preferably of hexagonal shape.

The inner electrode 54 preferably has a body portion I06 and is provided adjacent its bottom end with an enlarged outwardly flaring portion I08. The outer electrode 56 is concentrically mounted on the inner electrode 54 and is insulated therefrom by suitable insulators I I0, H2 and H4, and is insulated from the base member I00 by means of a suitable insulator H6.

The insulator preferably extends over the entire cylindrical body portion 106 of the inner electrode 54, and may be formed of any suitable material such for example as mica. The insulators II 2 and I I4 may be concentrically mounted on the insulator I I0 and may for example be formed of ceramic material.

It will be noted that the lower body portion of the outer electrode 56 is flared outwardly in the base member I00. The insulator II 6 may for example be formed of mica and may be tapered in accordance with the taper of the lower body portion of the outer electrode 56 whereby the unit consisting of the inner and outer electrodes 54 and 56 with the insulators H0, H2, H4 and H6 may be securely bonded to the base member I00 by means of upper and lower flanges I I8 and I20 positioned to overlie the insulator '6.

Discs I 22 and I24 formed of copper or other suitable material may be interposed between the insulator H2 and the lower surface of an inwardly directed flange I26 formed on the outer electrode 56, and the insulator I I4 and the upper surface of the flange I26 to take up mechanical differential in the manufacture of the parts.

The. upper end of the outer electrode is provided with threads I30 to receive the base of a coilsupporting member I3I surrounding the plug. The. member i3I is formed adjacent its upper end with a section of reduced diameter to receive an-insulator I33 formed of any suitable material such as'Bakelite.

Wrapped about the insulator I33 and the lower portion of the member I3I is the primary coil 36 wound with relatively coarse wire I36 as is customary. Surrounding the primary coil 36 is a core I38formed of iron or steel or other suitable electrical conducting material.

The secondary coil 52 preferably formed of smaller wire t lt than the wire I36 oi the primary coil 36 is Wrapped about the core I33. The primary and secondary coils 36 and 52 are covered at the top by means of an insulator M2 formed of Bakelite or other suitable material having 'a section I of reduced diameter to fit Within the core I38. A casing IE8 is provided to overlie the insulator 5 42 and secondary coil 52 to function as an additional core to assist the core 338. llhe casing Hit is suitably secured to an upwardly directed flange l54 carried by the coil supporting member I32.

The wires 32 and 34 from the induction coils 20, 22, 24, 26, 28 and 33 are connected to opposite ends of their associated primary coils 35. The wire 32 is as illustrated in Fig. 9 connected through a spring clip M5 to a central pole I46 positioned on the insulator I42 and connected through a wire Hi3 embedded in the insulator M2 to one end of the primary coil 36.

i The other wire 34 may be connected through a spring clip I47 to a furl 159 positioned on the insulator Hi2 and connected through a wire I52 extending through the insulator M2 to the other end of the primary coil 36. The furl I59 may be separated from the pole I43 by means of a suit between the primary and secondary coils 33 and 52 respectively, being of bell shaped contour, and the core EM surrounding the secondary coil 52 concentrate the magnetic lines of force. This concentrated electrical field induces a strong induction current in the secondary coil 52.

Opposite ends of the secondary coil 52:are connected to the inner and outer'electrodes 54 and 56 of the spark plug it. One end of the coil 52 may be connected through a wire i58 embedded in .the insulator M2 to a resistor IE!) engaging the end of the cylindrical body portion IE5 of the central electrode ti l.

The resistor I66 may be guided in a portion Hi2 of reduced diameter of the insulator I33, and may be yieldingly urged into engagement with the body portion Hit of the central electrode 54 by means of a spring portion I64 of the wire I53. The resistor I56 may be made of carbon or other goodresisting material. Where a resistor similar to that illustrated is employed, the electrodes 54 and 56 of the plug 6!! will not be subjected to such prolonged current and will therefore be longer lived because the resistors tend to' smooth out the electrical surge.

The other end of the secondary coil 52 is connected to the coil carrying member I3I as illustrated at 66. The flow of current is preferably from the secondary coil 52 through the central electrode 54, thence across the spark gap I68 to the outer electrode 56 and back to the secondary coil 52.

The operatic-n of this embodiment of the invention is as follows: Current, induced in the induction coils by rotation of the magnet ID is transmitted through the wires 32 and 34 to the high tension coil or transformer associated with each spark plug to increase the voltage that provides a high potential spark. The current from the induction coils produces an inductive surge current in the primary coil 35, and this current is concentrated by the core I38 and the outer shell I46. The secondary coil 52 is thereupon energized whereupon a high intensity spark is produced. This high potential spark is directed through the electrodes to produce the desired spark in the spark gap its to fire the charge in the cylinder, and the circuit is thereafter completed by passing through the other electrode back to the secondary coil.

The inner and outer electrodes 54 and ES and the coil supporting member ISI may be formed of any suitable material having good electrical conducting characteristics, such for example as steel.

It will be noted that this spark plug is thoroughly shielded against moisture and is advantageously insulated to prevent undesired electrical losses or short circuiting. Greater voltage can therefore be exerted to fire the charge in the cylinder of the engine.

The entire circuit is self-contained and it is not necessary to use the engine or any other part of the vehicle as a ground. Since the vehicle is not used as a ground for the ignition circuit it is not efiective as a variable capacitor, and the necessity for bonding the component parts of the vehicle together is entirely eliminated.

In view of the fact that low voltage current is transmitted to the transformers associated with the spark plugs, it is unnecessary to employ shielding on the spark plug wires to prevent leakage from the high tension wires as is now customary.

N0 spark gap is present in the distributor as the low intensity current is induced in the induction coils by movement of the magnet with reference to the coils. Undesirable signals from this source are therefore eliminated. The spark gap between the electrodes of the spark in the combustion chambers being insulated from the engine will not transmit undesirable signals as is customary with presently used ignition systems.

Fig. 10 illustrates a somewhat modified form of spark plug over that disclosed in Figs. 7 and 8. Corresponding parts have therefore been given corresponding reference numerals with the addition of I00.

It will be noted that the inner electrode 206 is shorter than the inner electrode of the plug illustrated in Figs. 7 and 8, and that the outer electrode 225 is provided with a plurality of spaced heat radiating fins 21B, positioned beneath the threaded portion 236.

The lower portions of the inner and outer electrodes 206 and 226 have parallel, preferably angu- 9 to define there-between a spark gap 216. The parallel spark gap 216 gives greater opportunity for the plug to clear itself in the event of fouling and will therefore frequently prevent short circuiting of the plug.

A transformer of the general type illustrated in Fig. 7 may be employed with the plug illustrated in Fig. 10, or it may be connected to conventional magneto or distributor circuits. When so used, the central electrode 205 is preferably E connected to the high tension lead, and the outer electrode 226 is grounded back to the electrical source. A confined circuit is thus provided in conventional magneto or distributor circuits whereupon it is unnecessary to employ the body of the engine or vehicle to complete the circuit from the source of electric current such as a battery or magneto.

Figs. 11 to 13 illustrate an embodiment of the invention which is similar in many respects to ii that illustrated in Figs. 1 to 6. Corresponding parts have therefore been given corresponding reference numerals with the addition of I00.

In this embodiment, the invention is applied to a system wherein a battery 200 is employed as the source of electric current. One wire 202 from the battery is connected through leads 264 and 286 preferably embedded in the housing I58 with a centrally disposed spring pressed contact 206. The contact 208 engages a cooperating contact member 2| I) embedded in a distributor arm 2I2 driven by the shaft H4.

The arm 2!?! carries an electro-magnet 2I6 having a core 2 I8 adapted to move between cooperating pole pieces 222 and 224 of the induction coils I20, I22, I24, I26, I28 and I30 operably connected through the wires I32 and I34 to the transformers associated with the spark plugs 40, 42, 44, 4.6, 48 and 50 of the engine as illustrated in Fig. 1. The pole pieces 222 and 224 are portions of the cores of the induction coils, and as illustrated in Fig. 13 may be of laminated construction. The induction coils I20, I22, I24, I26, I28 and I30 may be suitably attached to the housing I58 by suitable brackets 226.

The electro-magnet 2I6 comprises a suitable core M8 and a coil 228 wrapped about the core. One end of the coi1.228 is connected through a wire 23!] with the contact member 2I0, and the other end of the coil 228 is connected through a wire 232 with a contact ring 234. The contact ring 234 embedded in the rotating arm 2I2 is connected through a spring pressed slip contact 236 and leads 238 and 240 preferably embedded in the housing I58 with a terminal 242 operably connected to the battery 200 through a suitable breaker mechanism operated by a cam 244 rotating with the arm 2I2.

The cam 244 having a number of lobes 246 corresponding with the number of spark plugs to be fired is interposed between the shaft H4 and the arm 2 I 2 to be actuated by the automatic spark advance mechanism I68 and rotate with the arm 2I2.

A plate 248 positioned in the housing I58 is provided with an electrical contact point 250 carried by a bracket 252 connected with the terminal 242 by a wire 253, an arm 254 pivotally mounted at 256 on the plate 248 is provided with an electrical contact point 258 adapted to be actuated by the cam 244 to engage the contact point 250 when the core 2 I8 of the electromagnet 2 I 6 carried by the arm 2 I2 is substantially aligned 10 with the poles 222 and 224 of the induction coils I20, I22, I24, I26, I28 and I30.

The arm 254 is provided with a spring 260 engaging an electrical connection 262 positioned in the housing I58, and connected to the battery 208 through a wire 263, to yieldingly urge the arm 254 to rotate about its pivot 256 to engage the contacts 250 and 258. An actuating projection 264 carried by the arm 254 is adapted to engage the lobes 246 of the cam 244 to maintain the contacts 250 and 258 separated except when the electromagnet 2I6 is aligned with one of the induction coils.

The operation of this embodiment of the inventlon is as follows: Current flows from the battery 200 through the wire 202 and leads 204 and 286 to the spring pressed contact 208 engaging the contact member 2I0 embedded in the rotating arm 2| 2. The contact point 2I0 is connected with one end of the coil 228 of the electromagnet 2I6 through a wire 230, and the other end of the electromagnet is connected through the wire 232 with the circular contact rin 234 embedded in the rotating arm 2I2. Current from the contact ring 234 passes through the spring pressed contact 236 and leads'238 and 240 to the terminal 242. Current from the terminal 242 passes through the wire 253 to the bracket 252 carried by the plate 248 having the conta-ct'point 250 carried thereby.

When during rotation of the arm 2I2 the electromagnet 2 I6 is aligned with the pole pieces 222 and 224 of one of the induction coils I28, I22, I24, I26, I28 and I30, the cam 244 engaged by the actuating projection 264 of the arm 254 permits the contact 258 carried by the arm 254 to engage the contact 250 whereupon the circuit through the arm 254, spring 260 and wire 263 is completed to the battery 200. Current then flows through the coil 228 of the electromagnet 2I6 to successively induce a charge in each of the coils I20, I22, I24, I26, I28 and I30. This induced charge is transmitted through the wires I32 and I34 to the transformer illustrated in Fig. '7 as being associated with each of the spark plugs in the combustion chambers of the engine.

It will be apparent that the battery 200 is connected to the coil 228 of the electromagnet 2I6 only when the core 2I8 of the electromagnet 2I6 is aligned with the pole pieces 222 and 224 of one of the induction coils. The cam actuated distributor mechanism operates to provide. a sharp timing whereupon low voltage current may be directed to the transformer associated with each of the spark plugs at the precise instant when it is desired to fire the charge in the combustion chamber of the engine. The automatic spark advance mechanism I68 operates to vary the time of firing the charge in accordance with variations of the speed of rotation of the engine whereupon thcmost desirable conditions of firing the charge may be attained.

If desired the electromagnet'lifi and the induction coils associated therewith may be of such proportions that sufficiently high intensity current is induced that separate transformers on the spark plugs are unnecessary.

Figs. 14 l5 illustrate a further modified form. of the invention wherein a battery is employed as the source of electric current. An engine driven shaft 300 is mounted in a housing having a plate 384 positioned therein. The shaft 300 drives a cam 306 having spaced lobes 308 corresponding in number with the number of contact point 328 carried by a bracket 333 mounted on the plate 384. The bracket 338 has a spring contact 332 engaging a ring 334 carried by a member 336 mounted on the cam 38%. The ring 334 is connected through a contact 333 with a spring pressed contact 340 mounted in a portion 34l of a cap 343 and connected through.

suitable leads 342 with one end of primary coils of transformers 344. A number of transformers 344 corresponding with the number of spark plugs to be fired are mounted in the housing 362.

The member 336 is provided with another contact member 346 adapted to engage spaced contact members 348 carried by arms 356 projected inwardly from the walls of the housing 382. A number of arms 358, having contact points 348 to be engaged by the contact member 346, corresponding with the number of spark plugs to be fired are employed. The arms 358 are electrically connected by means of a connector 352, and are connected through the housing 332 with the other terminal 354 of the battery 322.

The contact member 346 carried by the memher 336 is connected through a spring pressed slip contact 356 and suitable leads 358 with the other side of the primary coils of the transformer 344. Opposite ends of the secondary coils of the transformers 344 are connected through suitable leads 368 and 362 with the transformers associated with each spark plug. If desired the leads 368 and 362 maybe connected to the spaced elec trodes of the spark plugs 48, 42, 44, 4E, 43 and 58 illustrated in Fig. 1.

The operation of this embodiment of the invention is as follows: As the member 336 carried by the shaft 33!? rotates, the lobes 383 of the earn 386 permit the contact members 326 and 328 to 7 close at the time it is desired to fire a spark in one of the spark plugs of the engine. Vfhen the contacts 323 and 328 engage, electric current flows from the battery 322 through the terminals 328 and 358, spring 3|6, arm 312 contacts 323 and 328, bracket 330 spring contact 322, ring 334, contacts 333 and 348 and lead 342 to one end of the primary coil of one of the transformers 344.

At the time the lobes 388 of the cam 383 permit the contacts 326 and 323 to close, the contact member 346 positioned. in the member 336 interconnects the contact member 348 of one of the arms 356 to complete the circuit from the battery 322 terminal 354 and lead 358 to the other side of the primary coil of one of the transformers 344. The current. thus induced in the primary coil of one of the transformers 344 energizes the secondary coil of the transformer and the current from the secondary coil is transmitted through the leads 368 and 362 to the primary coil 36 of one ofthe spark plugs illustrated in Fig. 7.

It will be understood that a transformer 344 is used for each of the spark plugs to be fired. Where this embodiment of the invention is emplayed, the current transmitted to the transformer associated with each spark plug is stepped up to transmit relatively high voltage to the transformer associated with each spark plug.

The transformers 344 may be of any desired size with respect to the transformers associated with each spark plug to provide the desired intensity of spark between the electrodes of the spark plug. For example the voltage of the current may be slightly increased by the transformers 324 and materially increased by the transformers associated with the spark plugs. The voltage may if desired be considerably increased by the transformers 344, and then be somewhat further increased by the transformers associated with the spark plugs, or the voltage may be increased substantially uniformly or in any desired ratio by each of the transformers.

It will of course be apparent that if desired the transformers associated with the spark plugs may be ispensed with and the leads and 362 from the transformers 334 connected directly to the electrodes of the spark plugs. High voltage current would then be transnntted to the spark plugs through a closed circuit system wherein the engine would not be employed as a ground the circuit.

Fig. 16 illustrates an adapter to connect with the leads 358 and 362 from the transformers 344. The lead 363 may be connected with a pole piece 384 centrally disposed in an insulating grommet 366. The lead 332 may be connected with a ring 383 concentrically mounted the grommet 386 relative to the pole piece 364 to be insulated therefrom. The pole piece 364 engages a contact member 3'53 connected for example to one end of the secondary coil of one of the transformers 334. The ring 368 may be engaged by a spring clip 312 connected for example to the other end of the secondary coil of the transformer 344. The pole piece 364 and the ring 368 may be connected to wires 3'14 and 316 respectively leading through a conduit 318 to the electrodes of a spark plug or to the transformer associated with a spark plug.

Fig. 17 illustrates amodified form of connector wherein one of the wires 314 housed within the casing 318 is connected through a spring clip 389 with a centrally disposed contact or electrode member 382. The other wire 313 is connected to a ring 384 embedded in a body portion 383 of the connector to be insulated from the clip 382. The ring 384 maybe engaged by a spring clip 388 connected to the other contact or electrode member and concentrically mounted relative to the contact 382 to be insulated therefrom. A cap 338 engaging a shoulder 392 of the body portion 386 may be threaded at 394 on a body portion 396 surrounding the contact or electrode members 382 and 388 to seal the connections against the entrance of moisture.

The embodiment of the invention illustrated in Fig. 18 is similar in many respects to that illustrated in Figs. 14 and 15, corresponding parts have therefore been given corresponding ref erence numerals with the addition of 100.

The leads 4-42 and 458 connected through the spring pressed contacts 449 and 453 with the battery through the distributor mechanism conmeet with terminals m and 472 leading to the transformers associated with the spark plugs of the engine as illustrated in Fig.1 In this embodiment of the invention, low voltage current from the distributor is directed to the transformers of the spark plugs and is stepped up there to provide the desired high intensity spark between the electrode of the spark plug to ignite the charge within the cylinders of the engine.

Fig. 19 illustrates one desirable method of connecting wires 315 and 31! to the spaced electrodes of a dual electrode spark plug. The wires 315 and 31'! may be connected to the transformers 344 illustrated in the embodiment of Figs. 14 and or one of the wires 315 or 31'! may be connected to the high tension lead of a conventional mag-- neto or distributor circuit, and the other of the wires 375 or 31! may be grounded back to the source of electric current. The wires 315 and 311 may project into a housing 38! mounted on a dual electrode spark plug 343.

The spark plug illustrated in Fig. 19 is similar in many respects to that illustrated in Fig. '7, Corresponding parts have therefore been given corresponding reference numerals with the addition of 20.

It will be noted that the base member 300 is provided adjacent its upper end with screw threads 38!) to receive a threaded plug 382 having an inwardly directed flange 384 to overlie the upper edge of the insulator 3 6 to clamp the component parts of the spark plug in assembled relation. The inner electrode 306 is provided adja cent its upper end with a threaded portion 386 to receive a threaded member 388'to engage the insulator SM and maintain the upper portions of the plug in the assembled relation. This plug may be. readily disassembled for cleaning purposes or for the replacement of new elements.

The wire 315 may be connected through the resistor or contactor 36! with the central electrode 306, and the wire 31! may be connected to the outer electrode 326 as illustrated. The housing 38! is provided with a threaded ring 353 to which the wire 31! may be connected. The ring 390 may be screwed onto the threaded portion 338 of the outer electrode 325 to securely seal the upper end of the spark plug assembly.

If desired a shield may be positioned on the spark plug where the dual electrode plugs are employed without the transformers, and the high voltage current is transmitted to one of the electrodes of the spark plug. Fig. 20 illustrates one desirable form of shield 40! having a threaded end section 403 adapted to receive a furl 405 surrounding the casing 319 having the current carryin wires 315 and 31! housed therein. If desired the casing 40! may be split and have overlapping edges to securely seal the upper end of the spark plug against the entrance of moisture. The shield may be formed at the bottom end with an inwardly directed flange 48'! to overlie the housin 38% of the embodiment illustrated in Fig. 19. Fig. 21 illustrates a modified form of resistor element adapted to be interposed between one of the electrodes of the spark plug and the wire 4! connected to a transformer associated with the spark plug or to a high tension wire, where separate transformers are not employed at the spark plugs, as illustrated in one form of the embodiments of the invention illustrated in Figs. 11 to 14. A removable and replaceable resistor element 4l3 may be interposed between the electrode and a shell M5, connected to the wire 4! and shaped to receive the resistor 443. A spring 4!! yieldingly urges the resistor 4!3 into engagement with the electrode 405 of the spark plug. The resistor 4! 3 may be removed and replaced by resistors of different lengths to vary the resistance, or resistors formed of different material but of the same length may be employed to vary the resistance introduced. The resistor 4!3 may advantageously be formed of carbon, powdered metal, tungsten or other suitable material.

Fig. 22 illustrates a further modified formof resistor wherein a resistor element 42! having a groove 423 formed adjacent one end is provided With a spring clip 425. The spring clip 425 may be introduced into a cylinder 42! formed in a threaded member 43! operably connected to one of the electrodes 406 of the spark plug. Resistors of this type may be formed of diiierent material to provide the desired variation of resistance, and may also be formed or different lengths to provide the desired operating characteristics.

Figs. 23 and 24 illustrate a further modified form of spark plug having spaced parallel el'ec trodes 435 and 431. The electrodes are positioned in a threaded base member 439 adapted to be secured in the cylinder of an engine to position the spark gap forming portions 44! and 443 of the electrodes 435 and 43'! respectively in the combustion chambers of the engine.

The electrodes 435 and 43! may be insulated from each other and from the base member 439 and engine by any suitable form of insulating material such for example as stacked mica disks 445. It will be apparent that the lowermost disk is supported on shoulders 44! formed in the base member 449 and in the lower shanks of the electrodes 435 and 43?. The upper end of the-base member 439 is'formed with an inwardly directed flange 449 to overlie disks of larger diameter and maintain the plug in the assembled relation.

It will be noted that the electrode 435 is somewhat longer than the electrode 431 to separate their upper ends and prevent short circuiting between the upper ends of the electrodes and to insure the formation of the charge firing spark in the spark gap 45! between the portions 44! and 443 of the electrodes.

A ring 453 is positioned adjacent the top of the electrode 43'! and is contoured to overlie a group of the disks 445 and maintain a desired pressure on the disks 445 between it and the flange 449 of the base member 439. The upper end of the electrode 43'! is flared outwardly as illustrated at 455 over the ring 453 to insure good electrical contact therewith. The inner portion of the ring 453 may be cut out, and contoured mica or other suitable insulating disks 459 positioned therein as illustrated in Fig. 23.

A ring 43! may be positioned above the smaller disks surrounding the longer electrode 435, and the upper end of the electrode 435 may be flared outwardly as illustrated at 45'! to maintain a desired pressure on the upper disks and to insure good electrical contact therewith.

A transformer 463 similar to that illustrated in Fig. 7 may be employed with this spark plug, the low intensity contacts from the source of electrical energy being connected with opposite ends of the primary winding. One end of the secondary winding of the transformer may be connected to the electrode 435 through a contactor 46'! engaging the ring 46! engaging the electrode 435. The other end of the secondary winding of the transformer may be connected to the electrode 431 through the ring 453. threaded to receive the transformer 463 as illustrated at 465.

It will be understood that if desired this spark plug may be used without the transformer as discussed above.

Features disclosed but not claimed herein are being claimed in my copending application Serial Number 50,720 filed September 23, 1948.

I claim:

1. An ignition circuit comprising a battery, spaced induction coils, a rotatable electromag' net adapted to move with reference to the induction coils, connecting means between the battery and one end of the elcctromagnet, connecting means between the battery and the other side of the electromagnet, and means to close the circuit between the battery and the electromagnet when the electromagnet is aligned with one of the induction coils.

2. An ignition circuit comprising spaced induction coils, a rotatable member, an electromagnet having a coil carried by the rotatable member to move with reference to the induction coils, a source of electric energy, connecting means between one end of the coil of the electromagnet and said source, a circuit interrupter operated by the rotatable member, connecting means between said source and the circuit interrupter, and connecting means between the circuit interrupter and the other end of the coil of of the electromagnet.

3. An ignition system including a spark plug, an induction coil spaced from said spark plug, a circuit including said induction coil and said spark plug as integral parts thereof, and means for causing low tension current to flow in said circuit, said means comprising an additional coil rotatable in a path adjacent said induction coil, and means for supplying current to said rotatable coil.

RAYMOND J. MILLER.

16 REFERENCES CITED The following references are of record in the of this patent:

UNITED STATES PATENTS Number Name I Date 858,196 Marshall June 25, 1907 995,400 Cavanagh June 13, 1911 1,164,113 Orswell Dec. 14, 1915 1,319,487 Powell Oct. 21, 1919 1,471,345 Milton Oct. 23, 1923 1,560,510 Hirsch Nov. 3, 1925 1,645,643 Crook 1;- Oct. 18,1927 1,984,939 Machumsohn Dec. 18, 1934 2,071,573 Randolph et al Feb. 23, 1937 2,081,500 Nowosielski May 25, 1937 2,098,002 Guerin et a1 Nov. 2, 1937 2,148,398 Bowman-Manifold et al.

' Feb. 21, 1939 2,180,704 Dietrich et al Nov. 21, 1939 2,182,061 Sparkes Dec. 5, 1939 2,266,614 Robinson Dec. 16, 1941 2,401,175 Morill May 28, 1946 2,414,692 Harkness Jan. 21, 1947 FOREIGN PATENTS Number Country Date 328,549 Germany Sept. 30, 1919 486,036 France Mar. 5, 1919

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