US2527211A

US2527211A - Ignition system

Info

Publication number: US2527211A
Authority: US
Publication date: 1950-10-24
Anticipated expiration: 1967-10-24

Description

Oct. 24, 1950 so 2,527,211

IGNITION SYSTEM Filed July 9, 1943 IN V EN TOR.

BY d 5mm, 5. Mwm/ MM A TTOP/VFY Patented Oct. 24, 1950 IGNITION SYSTEM Harry A. Brinson, Sidney, N. Y., assignor to Ben dix Aviation Corporation, New York, N. Y., a corporation of Delaware Application July 9, 1943, Serial No. 494,113

3 Claims.

This invention relates to electrical apparatus and more particularly to ignition means for internal combustion engines and the like.

One of the objects of the present invention is to provide novel booster ignition means adapted for use with either a low or high tension distribution ignition system for an internal combustion engine.

Another object of the invention is to provide novel means for supplying high voltage current to the spark plugs of an engine for creating sparks in the engine cylinders at predetermined times in timed relation with the operation of other parts of the engine;

Another object is to provide novel ignition means which are operable independently of the speed of the engine whereby starting of the engine is facilitated. 7

Still another object is to provide a novel method for'creating sparks across a gap, such as across the points of a spark plug in the cylinder of an internal combustion engine.

A further object is to provide a novel booster ignition system adapted for use in starting internal combustion engines which are normally operated by a magneto-generator or similar current generating means.

The above and further objects and novel features of the invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended to define the limits of the invention, reference'for this latter purpose being primarily had to the appended claims. In the drawings, wherein like reference characters refer to like parts throughout the several views,

Fig. 1 is a diagrammatic view illustrating one form of high tension distribution ignition system embodying the present invention; and,

I Fig. 2 is a diagrammatic view illustrating one form of low tension distribution ignition system embodying the invention.

" In the embodiment of Fig. 1, the invention is illustrated by way of example in the form of an ignition system for a 9-cylinder engine wherein the electrical energy for normal operation of the engine is generated by a magneto-generator or the like and is distributed to the spark plugs of an engine at relatively .high voltage. Any of many well-known types of magnetos may he employed for carrying out the invention "in this .means (not shown) capacity used in standard proximately .25 microfarad.

form, the magneto shown being of the type which consists of a 4-pole magnetic rotor 5 adapted to be driven in any suitable manner by the engine and a 2-pole stator 6 adapted to cooperate with rotor 5 .in a manner well understood in the art. Wound on stator 6,is an ignition coil consisting of a primary or low tension winding 1 and a secondary or high tension winding 8, said coils having the electrical characteristics ofa standard magneto.

One end of primary winding 1 is preferably grounded at'9 and there is a circuit breaker consisting of a movable point or contact I0 and stationary point or contact ll connected across it in the usual well-known manner to form a primary or low voltagecircuit. The points of the circuit breaker H], II are normally biased to engaged or closed position either by the resiliency of movable arm IZ or by other suitable resilient A rotatable cam [3 or any other suitable known means may be provided for periodically separating the points of circuit breaker Ill, ll to thereby interrupt the circuit through primary winding 1. Cam l3 may be driven by the engine in timed relation with rotor 5. In order to eliminate or minimize arcing at points IO, U, when the same are separated by cam l3, a condenser l4 may be connected across said points. This condenser is preferably of the magnetos, i. e., ap-

One'end of secondary winding 8 is preferably connected to the grounded or low potential end of primary winding 7, and the other end of said secondary winding is connected by lead I5'to the input terminal N5 of a high tension ignition distributor ll. High tension current flowing through lead l5 from secondary winding 8 is picked up by the rotating arm l8 of the distributor and delivered in a manner well-known in the art to the circularly arranged output terminals IQ of the distributor which are in turn connected by leads 2!] to spark plugs 2| in. the cylinders of an engine. One terminal of each spark plug is grounded in any suitable manner, as at 22.

The ignition system thus far described is of the character heretofore universally employed for hightension distribution of the current generated by the magneto. In the operation thereof, the rotation of rotor 5 induces alternating current at relatively low voltage in the primary circuit which includes winding 1' and circuit breaker l0, ll. At or about each time the induced current in the primary circuit reaches its maximum value, said circuit is interrupted by the separawinding 8.

3 tion of circuit breaker points in and H and the resulting sudden decrease in the electric current flowing in winding 1 and, hence, the sudden collapse of the magnetic field about windings 1 and 8 induces a current at high voltage in secondary Rotor 5, cam I3 and distributor iii are preferably all driven by the engine in timed relation to one another so that the high voltage current thus induced in the secondary circuit will flow from winding 8 through lead and distributor arm 18 to one of the distributor terminals l9 and thence to a spark plug 2| for creating an arc across the gap thereof. The combustible charges in the engine cylinders will thus be ignited in a predetermined sequence as is well understood in the art.

When starting an engine on which the above system is installed, the starting motor (not shown) does not ordinarily rotate the engine crankshaft and, hence rotor 5 at a sufficiently high speed to generate enough energy to create the necessary sparks at the spark plugs in the engine cylinders. Accordingly, for the purpose of starting the engine, a so-called booster source of electrical energy, such as a battery 23, may be employed. A battery having a rated voltage of '24 volts is ordinarily sufficient. The present 1 ntion contemplates novel means fo utilizing the'ene'rgy of battery 23 in a novel manner in conjunction with the ignition system heretofore discussed'to provide the necessary energy for starting the engine. In the form shown, one terminal of the battery is connected to ground at 24 and the other terminal thereof is connected through a switch 25 to one end of a coil 26 which, together with a metallic core 21 on which it' is wound, constitutes an electro magnet for opera 'ng a pair of

buzzer contacts

28, 29 in a manner to be more fully described hereafter. Switch 25 may be manually operable and normally biased to open position by any suitable means, such as a spring, or it may be an automatic switch adapted to be mechanically or magnetically opened whenever the engine is operating ata sufficiently high speed to insure the genelectrical energy by magneto 5, 6. Theother end of coil 26 is connected by means of a lead 30 to buzzer contact 28, which is mounted on a pivoted arm 3! and is normally biased into engagement with contact 29 by a spring 32 or other suitable resilient means. Buzzer contact 29 is connected by means of a lead 33 to circuit breaker contact II and the ungrounded end of primary winding 1. A condenser 34 which preferably has a capacity of approximately .25 microfarad is connected in shunt with

buzzer contacts

28, 29 to reduce arcing between the same. I

Inorder to reduce the amount of current which flows through coil 26 for purposes to hereinafter appear and for other reasons which will appear hereinafter, a resistance 35, which preferably has a value of from 8 to 12 ohms (approximately), is connected in shunt with said coil. The ohmic value of resistance 35 and the physical and electrical characteristics of the

buzzer breaker parts

28, 29, 3!, 32 and electro-

magnet

26, 21 for operating said breaker are preferably :such that

points

28, 29 will be electromagnetically separated whenever the current flowing in lead 33 reaches a value of from 7 to 9 amperes. Tl'le'inductance of coil 25 is preferably no more than 3 to 4 millihenries and the overall distribed resistance of lead 33 should be kept below approximately one ohm in most installations.

eration of adequate For the purpose of rendering the ignition sys-- tem inoperative and, hence, prevent operation of the engine on which the same is mounted, a suitable ignition switch 36 may be provided for grounding the high potential end of primary winding 1, as at 31. Thus, when switch 36 is in closed position, both ends of primary winding 1 will be connected to ground and thereby render circuit breaker 10, H incapable of interrupting any flow of current through said winding. Also, when switch 36 is in closed position, very little, if any, current will flow from battery 23 to winding 1 when switch 25 is also in closed position.

When it is desired to start the engine, the starting or booster circuit may be rendered operative by closing switch 25 when ignition switch 36 is in open position, it being understood that the closing of switch 25 may be effected by closing the circuit to a starting motor (not shown) which is operative to slowly turn the crankshaft of the engine on which the ignition system is installed. Current will then flow from battery 23 through coil 26' and resistance 35. Since the only function of electro-

magnet

26, 21 is to separate

points

28, 29, only a small portion of the current from the battery need flow therethrough, From the connected ends of coil 26 and resistance 35, the current flows through

contacts

28, 29 into lead 33. When circuit breaker contacts H], H are in closed position, the current flows from lead 33 across said contacts to ground at 9. Whenever this current reaches a predetermined value in the vicinity of approximately '1 to 9 amperes, electro-

magnet

26, 21 becomes effective to separate

contacts

28, 29, thereby breaking the circuit through coil 26 and deenergizing the electro-magnet.

Contact points

28 and 29 are then closed again by spring 32 andthe cycle of operation is repeated in rapid succession. By reason of the resistance 35 and its ability to dissipate electrical energy, arcing across

points

28, 29 when the same are separated is substantially eliminated and, in addition, this resistance absorbs the inductive kick, so to speak, which results from the self-induction of coil 26 when the current therein drops suddenly upon the opening of

contacts

28, 29.

As pointed out above, the interrupted current from the booster mechanism flows to ground at 9 whenever circuit breaker contacts [0 and II are in closed position. When the latter contacts are moved to open position, i. e., at the instant a spark is desired in an engine cylinder, the interrupted booster current is directed through primary Windin 1. The flow of this interrupted current through the primary winding generates a high voltage interrupted current in secondary windin 8, which current is distributed to spark plugs 2i in the manner fully set out above. When the engine begins to run sufficiently fast, switch 25 may be released or automatically opened and the required energy for firing the spark plugs will be supplied by magneto 5, 6 in the manner heretofore described.

In the second embodiment of the invention illustrated in Fig. v2, the features of the invention are shown, by way of example, as being embodied in an ignition system for a 9-cylinder engine wherein the electrical current is distributed at relatively low voltage, the voltage being stepped up at a transformer or spark coil near each spark plug for the purpose of creating the necessary ignition spark across the points of the plug. In the form shown, the main ignition current for normal engine operation is generated by a magneto which comprises a magneto which embodies a magneto rotor 46 adapted to cooperate with stator poles 41 that are, in turn, connected by a core 48 on which a coil 49 is wound. Upon rotation of rotor 46, such as by the engine, alternating current at relatively low voltage is generated in coil 49 in a manner well understood in the art. The electrical characteristics of coil 49 will depend upon the particular engine on which the ignition system is utilized and may be readily determined by anyone skilled in the art. The re sistance of the coil should probably be quite low, a coil having a resistance of one-tenth of an ohm having been found satisfactory in one suitable embodiment.

One end of coil 49 is preferably grounded, as at 44, and the other end thereof is connected by a lead 59 to one contact of a circuit breaker 5!, the other contact of which is also grounded at 44 or otherwise. The contacts of circuit breaker 51! are normally urged to engaged or closed position by suitable resilient means (not shown) and are periodically moved out of engagement .with each other or to open position, as shown, by a rotatable cam52 which may also be driven by the engine in timed relation with rotor 46. Cam 52 may be of any suitable design but if the ignition system is used on a radial engine the cam is preferably of the compensated type having a lobe for each cylinder of the engine, said lobes being spaced to properly time the sparks in each cylinder. A condenser 53 is preferably connected across the terminals of circuit breaker 5? to reduce arcing when the contacts are separated.

The insulated or ungrounded terminal of circuit breaker 5i is connected to a suitable distributor D, which ma take the form of any of many well-known designs. In the illustrated embodiment, the distributor comprises a stationary insulated metallic ring 54 to which circuit breaker 5| is connected by means of a lead 55 and a plurality of arcuatecircularly arranged insulated contacts 56. Current delivered to ring 54 from magneto 45 or other suitable source through leads 56 and 55 is picked up by a carbon or similar brush 5! carried by rotating dis tributor finger 58 and conducted to contacts 56 through a brush 59 which is also carried by said finger and electrically connected with brush 51 by a conductor 69. Distributor finger 58 may be rotated by the engine in timed relation with cam 52 and magneto rotor 46. 7

Each of the distributor contacts 56 is connected by means of a lead 6| to the primary winding 62 of a spark coil, which winding is in turn connected to ground at 63. By controlling the flow of electrical current at relatively low voltage to coil winding 62, in the manner to be hereinafter described, a high tension current is induced in secondary winding 64 of the spark or ignition coil and creates a spark across the points of a spark plug 65 in the cylinder of the engine.

When it is desired to stop operation of the engine in which the above-described ignition system is installed, the ungrounded end of magneto coil 49 may be connected to ground through an ignition switch 65, one terminal of which is connected by a lead 61 to said coil. The other terminal of said switch may be grounded at 69 in any suitable manner.

In the operation of the ignition. system thus far described with ignition switch 66 in open position, the contacts of circuit breaker 5| are held in closed position during the time that current is being built up in coil 49 of the magneto generator. Each time the current in coil 49 approaches its maximum value, the points of circuit breaker 5| are opened by one of the lobes on rotating cam 52, whereupon the current from the coil must flow through leads 56 and 55 and distributor D in the manner fully described above to an ignition coil primary winding 62. This sudden surge of current, which results primarily from the self-inductance of coil 49, flows through winding 62 and is efiective to induce the necessary energy in the secondary circuit, which includes secondary winding 64, to create a spark across the spark plug gap at 65 in the engine cylinder. As distributor finger 58 moves brush 59 over the contacts 56, the spark plugs of the engine are successively fired in a predetermined sequence, the timing of each spark being determined'by the opening of circuit breaker 5 I.

In an ignition system of the above character, it is highly desirable to provide an electrical resistance in the primary or low voltage circuit. which is of sufficient magnitude to quickly dissipate the residual energy in said circuit after the occurrence of each spark at a spark plug. This dissipation of the residual energy is desirable in order to prevent arcing at the distributor contacts and to obviate the possibility of secondary sparks at the spark plugs when distributor brush 59 moves from one contact 56 of the distributor to another such contact. The desired resistance is preferably incorporated in the primary windings 62 of the transformer coils, thereby making it possible to use smaller wire and reduce the size of these coils to a minimum. In one satisfactory embodiment of the invention, resistance of 16 ohms in each primary winding- 62 and the leads connected with it has been found to be suitable. This resistance value may differ, however, with different installations.the.

most suitable value may be determined by resorting to oscillograph or like measuring means for determining the characteristics of the current in the primary circuit during operation of the engine. The resistance may be incorporated in the primary circuit at any desired point or may be distributed in the leads and should only be sufficiently large to produce the desired dissipation of the residual energy within a suitable interval to'accomplish the above-mentioned results.

Since rotor 45 is driven by the engine, sufficient electrical energy cannot be generated by magneto 45 to efiect the necessary sparks at the spark plugs when the crankshaft of the engine is turned slowly by a starting motor. Accordingly, for use in starting the engine a booster which is identical with the booster shown in Fig. 1 may be provided for cooperation in a novel manner with the main ignition circuit of Fig. 2 described above. The output lead 33 of the booster unit or circuit is, in this event, connected to lead 56, 55 of the main circuit. This connection is preferably made at a point such that a substantial portion, preferably substantially all of the resistance of each circuit involving a primary winding 62, will be on the same side of said connecting point as said primary winding-the resistance from said connecting point through magneto coil 49 or circuit breaker 5! should be relatively very low.

The booster unit per se of Fig. 2 operates as a buzzer or current interrupter in the same manner as described above in connection with Fig. 1

by cooperation with the main or low tension distribution ignition circuit in a somewhat difierent manner. With switch 66 open and switch 25 closed,

contacts

28, 29 are opened and closed in rapid succession by electro-

magnet

26, 21 and spring 32, thereby interrupting the flow of current from battery 23 to the main ignition circuit. Because of the high resistance in the circuit through the distributor and a primary winding 62, as heretofore explained, substantially all of the booster current will flow from lead 33 into lead 50 and thence through circuit breaker or coil 49, depending on whether said circuit breaker is closed or open. The timing of the initial spark in each cylinder of the engine is accordingly efiected during the starting operation by circuit breaker 5| in the same manner that the sparks are timed during normal operation of the engine.

With circuit breaker 5| in open position, current from the booster unit builds up at a relatively slow rate in coil 49 to a suitable value- '7 to 9 amperes having been found sufiiicient for one

operative embodimentwhile contacts

28, 29 are engaged and tends to drop off suddenly to zeroamperes when the latter contacts are separated to interrupt thev flow of current from the battery. The current decrease in coil 49 and the resulting collapse of themagnetic field about said coil causes a sudden surge of self-induced current through the only available circuit, i. e.,

through the primary winding 62, which is at that moment connected with said coil through distributor D. This sudden surge or increase of current flow through winding 62 is effective to induce a high voltage current in the associated secondary winding 64 and, hence, cause a spark at the gap of spark plug 65. Since the

contacts

28, 29 may open and close several times during each interval that circuit breaker 5| is held in open position by rotating cam 52, a veritable shower of sparks may occur at each spark plug and thereby facilitate starting of the engine.

When the engine starts, i. e., when rotor 46 is turned sufficiently fast by the engine to produce the required current for operating the engine without the assistance of the booster coil unit, starter switch 25 may be opened automatically or otherwise by any of many suitable means well-known in the art. Any operation of the booster coil unit or any interference thereof with the normal operation of the engine will thus be prevented during such normal operation.

There is thus provided an ignition system wherein novel, simplified means for supplying the starting energy for an internal combustion engine in combination with a magneto generator and circuit breaker means which are employed for supplying and controlling the eelctrical energy for normal operation of the engine are provided. A novel booster ignition means is provided for engine starting purposes, which system utilizes the circuit breaker of the main ignition system for timing purposes and is adapted for use in combination with either high tension distribution or low tension distribution ignition systerns. Additionally, the novel booster unit contemplated by the invention may be connected into the main ignition circuit by means of a relatively small amount of wiring and, hence, weight, cost, upkeep and possibilities of failures are reduced to a minimum. Additionally, the novel booster system provided is operable equally well at' all altitudes irrespective of the pressure Variations.

Although or two er. tion are illustrated in diagrammatic form. and

a l ents of theinvene described in the foregoing specification, it is expressly understood that various changes may be made therein without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art. For example, the booster coil unit may be connected into the main ignition circuit at points other than those illustrated and the various units of the ignition system, such as the magneto and distributor, may assume different forms than those illustrated. The number of cylinders or spark plugs may be varied and the values of the resistances, inductances, capacities, etc., which have been mentioned by way of example, may be varied in ignition systems for engines of difierent sizes and horsepower ratings. For a definition of the limits of the invention, reference is had primarily to the appended claims.

What is claimed is:

1. In ignition apparatus, a source of uni-directional electrical current, an electrical resistor connected at one end to one terminal of said source, a circuit breaker having one contact thereof connected to the other end of said resistor, resilient means for normally holding the contacts of said circuit breaker in engagement, means including a coil connected in parallel with said resistor {or electromagnetically opening said circuit breaker, an induction coil, a transformer coil having a primary winding, means connecting one end of said induction coil to one end of said primary winding, means, such as a common ground, for connecting the other ends of said induction coil and primary winding and the other terminal of said source, means connecting the other contact of said circuit breaker to said first named connecting means for said induction coil and primary winding, the resistance to current fiow through said primary winding being many times greater than the resistance to current flow through said induction coil, a second normally closed circuit breaker connected in parallel with said induction coil for diverting current from said source around said induction coil, and means for periodically opening said second circuit breaker.

2. In ignition apparatus, a source of uni-directional electrical current, an electrical resistor connected at one end to one terminal of said source, a circuit breaker having one contact thereof connected to the other end of said resistor, resilient means for normally holding the contacts of said circuit breaker in engagement,

means including a coil connected in parallel.

with said resistor for electromagnetically opening said circuit breaker, an induction coil, a transformer coil having a primary winding, means connecting one end of said induction coil to one end of said primary winding, means, such as a common ground, for connecting the other ends of said induction coil and primary winding and the other terminal of said source, means connecting the other contact of said circuit breaker to said first-named connecting means for said induction coil and primary winding, the resistance'to current flow through said primary winding being many times greater than the resistance to current flow through said induction coil, a second normally closed circuit breaker connected in parallel with said induction ccil for diverting current from said source around said induction coil, means for periodically opening said second circuit breaker, and means including a permanent magnet and a rotatable element for inducing alternating current in said induction coil when said element is rotated.

3. In an internal combustion ignition system comprising a magneto having a coil with one end thereof connected to ground, means for inducing alternating current in said coil, a periodically operable circuit breaker connected across said coil and a transformer coil having the ungrounded end of the primary Winding thereof connected to the ungrounded end of said coil, the combination therewith of a booster unit including a source of unidirectional electrical current, a second normally closed circuit breaker, an electrical resistor connected between one contact of said second circuit breaker and the ungrounded terminal of said source, electromagnetic means including a coil connected in parallel with said resistor for electromagnetically opening said second circuit breaker, the ohmic resistance of said resistor being many times greater than the ohmic resistance of said last-named coil, and means connecting the other contact of said second circuit breaker to the connection between the ungrounded ends of said magneto coil and said primary winding, the resistance to flow 10 of electrical current through said primary winding being many times greater than the resistance to flow of electrical current through said magneto coil.

HARRY A. BRINSON.

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