US3599617A - Multiple spark system of ignition - Google Patents

Abstract

An improved ignition system for an internal combustion engine is adapted to provide a series of relatively short duration sparks for ignition purposes during each successive ignition period of the engine cycle. The system in one embodiment utilizes a high speed commutator wheel adapted to interrupt the discharge of the ignition system capacitor through the primary winding of the ignition coil, thereby inducing approximately 2,000 sparks per second in the spark plug connected to the secondary winding of the coil.

Description

United States Patent Glenn B. Warren 1 13601 Myron St., Schenectady, N.Y. 12309 839,955

July 8, 1969 Aug. 17, 1971 [72] Inventor [21] Appl. No.

[22] Filed [45 Patented [54] MULTIPLE SPARK SYSTEM OF IGNITION 2 Claims, 2 Drawing Figs.

[52] us. c1 123/148 E, 315/209 511 Int. Cl F02p 3/06 50 Field of Search 123/32 SP,

[56] Reierences Cited 1 UNITED STATES PATENTS 2,866,839 12/1958 Kaehni 123/148E 3,277,340 10/1966 Jukes et a1. 123/148 E 3,291,110 12/1966 Peters 123/148 E 3,407,795 10/1968 Aiken et a1. 123/148 E Primary ExaminefLaurence M. Goodridge Attorney-Kane, Dalsimer, Kane, Sullivan and Kurucz ABSTRACT: An improved ignition system for an internal combustion engine is adapted to provide a series of relatively short duration sparks for ignition purposes during each successive ignition period of the engine cycle. The system in one embodiment utilizes a high speed commutator wheel adapted to interrupt the discharge of the ignition system capacitor through the primary winding of the ignition coil, thereby inducing approximately 2,000 sparks per second in the spark plug connected to the secondary winding of the coil;

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; MULTIPLE SPARK SYSTEM or IGNITION BACKGROUND OF THE INVENTION Research has indicated that air pollntion elements from automotive exhaust are a function of the richness of the engine 's fuel, mixture and thus one solution to the ever-increasing problem of air pollution is to modify conventional automotive enginesto enable them to operate more efficiently with leaner fuel mixtures. Attempts at such modifications have heretofore taken the form of providing relatively simple adjustments to either the carburetor or the ignition timing and have met with only limited success.

The principal drawback to operation an automotive engine in the lean condition (that is, with approximately percent to 20 percent more air than necessary for complete combustion as compared to 1'0 percent-20 percent less air that present engines require) is that the engine is prone to misiire d'ueto the ignition spark occuring prior to sufiicierit compression of the air-fuel mixture such as to reach an ignitable condition. For maxirniirn efficiency, it is necessary to ignite the fuel chargein each cylinder shortly before the piston reaches the top of each compression stroke. Since the point in the engine 'revolution a't which this point is reached varies with the engine speedand load as well as the fuel mixture, the optimum ignition point is not constant but will vary, and in a multicylinder engine it will vary from cylinder to cylinder-thus if the spark advance timing of a single spark ignition system is best for one condition'ofoperation it may be too far advanced for another and the ignition spark may take place before ignitable conditions arereached in the charge and'a misfire" results, thus sending unburned and pollution-making components out the exhaust. This is particularly prone to happen on engines with a lean mixturewhen running lightly loaded as down a long mild downgrade or in deceleration from a higher speed on the level, or in many cases at urban road speeds on the level. v

By providing a series of ignition sparks following the usual first spark at short intervals of time (l/2,000 second recommended) tests show that much of this 'misfiring can be avoided.

It might be said that multiple spark ignition systems are not new'inasmnch 'as the old-fashioned vibrator ignition coils used on some gas and gasoline engi'nes from about 1900 to [9 20, the Model T Ford for example, gave a series of sparks after the first one. The frequency of these sparks was from 300 to 450 per second due to inherent limitations in the mechanical vibrator used to interrupt the primary circuit of the coil plu the relatively long time required to magnetize and demagnetiz'e the magnetic core of the coil.

Analysis indicates that to secure the advantages of such an ignition, spark frequencies of 1,500 to 3,000 per second are required. Only by such frequencies can 3 'to '8 or so sequential sparks be secured during the ignition time delay period of the modern high speed automotive engine. Further analysis indicates that this frequency can only be secured with the short voltage rise time" of each individual spark which will insure consistent sparking in plugs whose resistance is lowered by It is, therefore, a principal object of the present inventionto provide a new and improved ignition system for present type automotive engines and particularly to provide an ignition system for improved operation of such engines on lean fuel-air mixtures, but also it should be applicable to the new fuel injec- SUMMARY OF THE INVENTION These and other beneficial objects and advantages are attained in accordance with the present invention by replacing the single spark present during each ignition period of conventional automotive ignition systems with a series of extremely short duration, high intensity, equally spaced sparks. The multiple sparks of the present invention may be obtained by providing a commutator wheel having a grounded brush in series with the engine breaker points and one terminal of the ignition capacitor of a conventional capacitor ignition circuit. The other terminal of the capacitor is connected to the primary winding of the ignition coil which is grounded on the opposite end, the secondary winding of which is connected to the spark plug, as in FIG. 1. Thus, when ignition for any particular deposits by using the so-called capacitor dischargel type of ignition system.

Anothergood application of this multispark ignition system may be in connection with stratified-combustion-direct-in- 'jection-spar'k-ignit'ed" engines. These-engines are represented by "the Texaco-Barber TCP (Texaco Combustion Process) stratified combustion engine and the Ford Combustion Process (FCI?)'engine recently described in the=literature. In such enginesit is almost impossible to get the single ignition spark at therighttime in "relation to the fuel injection, particularly over a wide range or load and speed. Pooroperation results underrnost conditions. By having a series of ignition sparks over a-Iinite time'starting ahead of 'injection,the entire timing of the cycle can be determined by'the'injection as'on a dieselv or compression ignition engine, and so design, operationa'nd maintenance problems are simplified.

cylinder is reached, and the breaker points close and the commutator wheel is rotating, the capacitor is intermittently allowed to discharge across the primary winding and shunted to ground. The intermittent surge current allowed to pass through the primary winding induces intermittent surges of high voltage with extremely short voltage rise time across the secondary winding of the coil, thereby providing the desired series of repetitious sparks across the spark plug gap. The frequency of the spark is determined by the speed of rotation of the commutator wheel.

In an alternate and improved embodiment of the invention, a silicon controlled rectifier (which hereinafter is abbreviated to SCR.) is provided, as in FIG. 2. The anode of the SCR is connected to one terminal of the ignition capacitor, the cathode is grounded, and the gating terminal is connected to the commutator wheel. The other terminal of the capacitor is connected to the ground through the ignition coil primary so that discharge of the capacitor occurs only when the SCR receives a gating signal. The commutator brush is connected to the low voltage power supply so that each time the commutator brush makes contact with the conducting portions of the commutator wheel, the SCR receives a gating signal from the power supply. The engine timer which comprises a set of breaker points that extend across the power supply to ground serve to short the gating signal to ground when closed, thereby allowing the repetitious series of ignition sparks to occur only upon the opening of the breaker points. This alternate embodiment is particularly well suited to conventional automotive usages wherein sparking is designed to occur upon the opening of the breaker points. It has the further advantage that very low voltages and current flows are required of the rotating commutator contacts.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FIG. 1 is a schematic representation of a multispark ignition circuit in accordance with the present invention adapted to operate upon the closing of the ignition timer breaker points and FIG. 2 is a schematic representation of an alternate embodiment of the invention designed to operate upon the opening of 'the breakerpoints.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference is now made to drawings and to FIG. I in particular, wherein the multispark ignition system of the present inpresent case, the l2-vo1t DC battery output generally available is transformed to approximately 200 v. DC The output 16 of voltage multiplier 14 is fed to one terminal of capacitor 18 through resistor 20. An ignition coil 22'is provided with primary winding 24 extending between ground and the other terminal of capacitor 18. The secondary winding 26 of ignition coil 22 is connected to spark plug 28 directly, or in the case of multicylinder engines through a distributor.

An engine timer 30 is provided which in conventional automotive engines comprises a set of cam-driven breaker points. One point contact is connected to the junction of resistor 20 and capacitor 18 and the other contact is connected to the terminal of commutator wheel 32. The commutator brush 34 is grounded. Commutator wheel 32 is driven by motor 36.

In operation, when the engine timing cam 38 closes breaker points 30, capacitor 18 will tend to discharge across the pri-. mary winding 24 of coil 22, thereby inducing a high voltage surge across the secondary winding 26 of the coil which causes a spark to jump across the gap of plug 28. The commutator 32, however, prevents capacitor 18 from discharging, except during those periods when the commutator brush 40, which is connected to ground, makes contact with the commutator wheel' contacts. During other periods, the capacitor is recharged by the power supply. Thus, capacitor 18 discharges intermittently across winding 24 resulting in a corresponding intermittentsurge of current in winding 26 of coil 22, produc-,

ing a series of sparks during each ignition period. Experimental results have indicated that a spark rate of 2,000 sparks per second provides optimum results. This frequency can be obtained by a proper proportioning of l the voltage supply 14, (2) the size of the capacitor 18, and (3) the valve of the resistor 20.

Conventional automotive ignition circuits presently available are designed to fire upon the opening of the breaker points rather than upon the closing of these points. In FIG. 2, an alternate embodiment of the present invention is depicted which is designed to fire upon the opening rather than the closing of the breaker points. The ignition circuit of the alternate embodiment includes a battery and voltage multiplier 52 as before. The output of voltage multiplier 52 is connected to one terminal of capacitor 54 through resistor 56. The other terminal of capacitor 54 is connected to the grounded primary winding 58 of ignition coil 60. The secondary winding 62 of coil is connected to spark plug 64.

The output of voltage of thev battery 50 is coupled to one contact 66 of the engine breaker points 69 at the midpoint of resistor 6868, the other end of which is grounded. The other breaker point contact 70 is also grounded.

A commutator wheel 72 driven by motor 74 is provided. Thebrush 76 of commutator 72 is connected to the junction of resistor 68-68, and the nongrounded breaker point contact 66 through resistor 78. The commutator wheel contact is connected to the gating terminal 80 of a silicon-controlled rectifier 82. The anode of SCR 82 is connected to the junction of resistor 56 and capacitor 54 and the cathode is grounded.

In operation, when the breaker points are closed, the output of the voltage of battery 50 is shunted to ground through the point contacts. When the points open, a fraction of the output of the battery voltage is intermittently applied to the SCR gating terminal so as to intermittently complete the circuit between capacitor 54, the primary winding 58, and ground thereby allowing the capacitor to intermittently discharge across the primary winding to produce a corresponding surge in the secondary winding 62. The reverse surge across the primary winding switches off the SCR allowing the capacitor to rechargeand the cycle to repeat.

Thus, in accordance with the above, an lmproved automotive ignition system is disclosed for providing multispark ignition to an automotive or other internal combustion engine.

What I claim is:

1. In an automotive ignition system of the type wherein a high voltage is induced in the secondary winding of an ignition coil for producing a spark in response to the discharge of a capacitor across the grounded primary winding of the ignition coil during the ignition period of said system, the improvement consisting of circuit means adapted to periodically interrupt said capacitor discharge at a fixed .frequency whereby to enable said capacitor to recharge and the circuit to recycle so as to produce a series of sparks during each ignition period; and wherein said ignition system further includes a pair of breaker point contacts, one of said contacts being connected to ground and the other contact being connected to a low voltage power supply through a first suitable resistor, connected to ground through a second suitable resistor and connected to one terminal of a commutator through a third suitable resistor; said capacitor includes a first terminal connected to the primary winding of said ignition coil and a second terminal connected to a relatively high voltage source through a suitable resistor; said circuit means includes a silicon-controlled rectifier having an anode connected to the junction of said capacitor and said high voltage power supply, a grounded cathode, and a gate terminal connected to the other terminal of said commutator; said commutator includes a first terminal connected to a motor-driven commutator wheel and a second terminal connected to a commutator brush; and said ignition period comprises the time of separation of said breaker point contacts.

2. In an automotive ignition system of the type wherein a high voltage is introduced in the secondary winding of an ignition coil for producing a spark in response to the discharge of a capacitor across the grounded primary winding of the ignition coil during the ignition period of said system, the improvement consisting of first and second terminals of said capacitor, said primary winding extending between said first terminal and ground, first and second engine breaker point contacts, said second terminal of said capacitor being connected to said first engine breaker contact, a grounded commutator, a motor-driven commutator wheel of said commutator connected to said second engine breaker point contact whereby upon the closing of the engine breaker points said commutator periodically interrupts the discharge of said capacitor through said primary winding enabling said capacitor to recharge and the circuit to recycle so as to produce a series of sparks during each ignition period.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 599, 617 Dated August 17, 1971 Inventor(s)' Glenn B. Warren It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

At Col. 1, line 16, "operation" should beoperating;

line 49, change "vibrator" to-"vibrator"-;

At Col. 2, line 5, change "fuel injec-" tofuelinjec line 6, change "tion spark" to-tionspark line 64, change "multispark" tomultispark;

line 75, change "multispark" tomulti-spark-;

At Col. 3, line 7, change "200 v. DC" to-2OO to 300 volts DC.-;

line 9, after "with" insert-its;

line 13, change "multicylinder" to-multicylinder;

line 37, change "valve" to-value-;

line 53, change "midpoint" to-midpoint;

At Col. 4, line ll, change "off" to-OFF,- and line 14, change "multispark" to-multi-spark.

Signed and sealed this 29th day of February 1972.

(SEAL) Attest:

ED MRI) PLFLETCHER, JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents

Claims (2)

1. In an automotive ignition system of the type wherein a high voltage is induced in the secondary winding of an ignition coil for producing a spark in response to the discharge of a capacitor across the grounded primary winding of the ignition coil during the ignition period of said system, the improvement consisting of circuit means adapted to periodically interrupt said capacitor discharge at a fixed frequency whereby to enable said capacitor to recharge and the circuit to recycle so as to produce a series of sparks during each ignition period; and wherein said ignition system further includes a pair of breaker point contacts, one of said contacts being connected to ground and the other contact being connected to a low voltage power supply through a first suitable resistor, connected to ground through a second suitable resistor and connected to one terminal of a commutator through a third suitable resistor; said capacitor includes a first terminal connected to the primary winding of said ignition coil and a second terminal connected to a relatively high voltage source through a suitable resistor; said circuit means includes a silicon-controlled rectifier having an anode connected to the junction of said capacitor and said high voltage power supply, a grounded cathode, and a gate terminal connected to the other terminal of said commutator; said commutator includes a first terminal connected to a motor-driven commutator wheel and a second terminal connected to a commutator brush; and said ignition period comprises the time of separation of said breaker point contacts.

2. In an automotive ignition system of the type wherein a high voltage is introduced in the secondary winding of an ignition coil for producing a spark in response to the discharge of a capacitor across the grounded primary winding of the ignition coil during the ignition period of said system, the improvement consisting of first and second terminals of said capacitor, said primary winding extending between said first terminal and ground, first and second engine breaker point contacts, said second terminal of said capacitor being connected to said first engine breaker contact, a grounded commutator, a motor-driven commutator wheel of said commutator connected to said second engine breaker point contact whereby upon the closing of the engine breaker points saiD commutator periodically interrupts the discharge of said capacitor through said primary winding enabling said capacitor to recharge and the circuit to recycle so as to produce a series of sparks during each ignition period.

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