US 3620201 A
Description (OCR text may contain errors)
United States Patent  inventors Glenn B. Warren 1361 Myron St., Schenectady, NY. 12309; John Randolph Morgan, 170 E. Coronado Road, Phoenix, Ariz- 85004  ApplNo. 864,417  Filed 0ct.7, 1969  Patented Nov. 16,197]
 SOLID STATE MULTISPARK IGNITION SYSTEM 2 Claims, 1 Drawing Fig.
 U.S.Cl.. 123/148E  lnt.Cl F02pl/00  FieldofSeareh 123/148E; 315/223  References Cited UNITED STATES PATENTS 3,291,110 12/1966 Peters 123/148 3,312,860 4/1967 Storm 123/148 3,331,986 7/1967 Hardin 123/148 3,357,415 12/1967 i-luntzinger 123/148 3,367,314 2/1968 liirosawa 123/148 3,372,684 3/1968 Gilbert.... 123/148 3,398,353 8/1968 Noddin.... 123/148 3,408,993 11/1968 Chavis 123/148 3,472,216 10/1969 Clybome 123/148 3,490,426 l/l970 Farr 123/148 3,277,340 10/1966 Jules..... 123/148 3,349,284 10/1967 Roberts...... 123/148 3,394,690 7/1968 Bell 123/148 3,489,129 l/1970 lssler 123/148 3,500,809 3/1970 Hohne 123/148 1., l w eerc e '4'4A S omee QEC /f/EQ .i- -ml l ll G Assistant Examiner-Ronald 8. Cox Attorney-Kane, Dalsimer, Kane, Sullivan and Kurucz ABSTRACT: A solid state circuit provides a series of short duration short voltage rise time sparks for automotive engine ignition purposes. it is well known in the ignition art that short duration sparks concentrate the energy and promote ignition, and that short voltage rise time characteristics in an ignition system promote good firing even though the spark plugs are covered with deposits. A Capacitor Ignition System" such as is described here has these characteristics and is used as the basis of a new system which will give a continuing series of sparks after the first one. The circuit includes two Zener diodes in series with the collector of a transistor switch, the collector of which is connected to the gating terminal of a silicon controlled rectifier. The SCR, when gated, connects the ignition system capacitor to the primary of the ignition coil and thus enables the capacitor to discharge across the coil. The SCR receives the gating signal when the Zener diodes and the transistor conduct, which occurs each time the charge on the capacitor reaches the avalanche level of the diodes and the points are open. in order to do this, the base of the transistor switch is connected to the ignition system breaker points so that the circuits become operative only when the breaker points open The present circuit serves to replace the single spark per ignition of conventional automotive ignition circuits with a series of sparks generated at a predetermined frequency.
BACKGROUND OF THE INVENTION In the currently pending application of Glenn B. Warren entitled MULTISPARK IGNITION SYSTEM filed the advantages of multispark ignition over single spark ignition are set forth. This application also discloses a method of obtaining multispark ignition wherein a motor driven commutator wheel is utilized to provide the desired multispark frequency. Although mechanical and electromechanical components as that of the pending application operate properly, they require periodic maintenance, repair, and replacement of worn parts to operate within the degree of accuracy necessary for smooth engine performance. Further, such mechanical components tend to be adversely affected by weather and climate conditions.
SUMMARY OF THE INVENTION It is, therefore, the principal object of the present invention to provide a solid state control circuit adapted to be utilized with a conventional automotive ignition system for purposes of providing a series of short duration sparks during each ignition period.
The basic principle employed here is to provide a solid state circuit and devices whereby the rise in voltage on the main capacitor in the circuit of a capacitor discharge type ignition system as it is recharged will serve when it reaches a predetermined level to cause a switch (usually an SCR) in the circuit to ground to conduct and so ground the capacitor and complete the capacitor-ignition coil primary winding circuit. This will permit the capacitor to discharge through the primary winding of the ignition coil and so induce a sparking voltage in the ignition coil secondary. Hence when the switch (SCR) is reopened in the usual manner by the reverse surge of current in the primary coil-capacitor circuit the capacitor can be recharged by the power supply, and will again discharge when the voltage in the charge of the capacitor is again built up, thus giving a series of sparks. The frequency of such sparks is determined by the characteristics of the several components of the system.
These and other beneficial objects and advantages are attained in accordance with the present invention in one embodiment by providing a control circuit including two Zener diodes in series with the collector of a transistor switch, the emitter of which is connected to the gating terminal of a silicon controlled rectifier (SCR). The SCR, when gated, connects the capacitor to the primary of the ignition coil and thus enables the capacitor to discharge across the coil. The SCR receives a gating signal when the Zener diodes and the transistor conduct, which occurs each time the charge on the capacitor reaches the breakdown level of. the diodes and the points are open. The base of the transistor switch is connected to the ignition system breaker points so that the circuit becomes operative only when the breaker points open. Each time the capacitor discharges through the primary of the ignition coil, a high voltage is induced in the secondary of the coil. The back current after discharge serves to turn OFF the SCR so as to allow the capacitor to recharge and then recycle so as to repeat thereby providing the desired series of repititious sparks. The frequency of the sparks is determined in part by the breakdown voltage of the Zeners and the speed of voltage recovery when the SCR is gated and should be on the order of 2,000 sparks per second. Other type solid state devices might be used in place of the Zeners to provide the triggering of the SCR when the proper voltage build up on the capacitor is reached.
BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawing is a schematic representation of the solid state multispark ignition system control circuit of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Reference is now made to the accompanying drawing wherein a schematic representation of an automotive engine ignition control circuit in accordance with the present invention is illustrated. The circuit includes a battery 10, the nongrounded terminal of which is connected through ignition switch 12 and resistor 14 to the nonground contact 16 of the breaker points 18. Thus, when the ignition switch and breaker points are closed, current flows from the battery through resistor l4 and the breaker points to ground. A DC voltage multiplier 20, comprising a suitable oscillator, transformer, and rectifier connected in a manner well known in the art, is provided to increase the output voltage of battery 10 and is connected to the junction of switch 12 and resistor 14. The multiplier serves to step up the voltage of battery 12 which would ordinarily be 12 volts to between 300 and 375 volts DC.
If multiplier 20 is not designed so that it can have a large voltage drop when the high voltage output is short circuited upon the SCR conducting, an inductance, resistor, or both may be required in the position of box 20' to protect the circuit from overload. On the other hand, if the design and the components of multiplier 20 are selected to withstand such surge, no protective components in box 20' are required.
The output of multiplier 20 is connected to one terminal of capacitor 22. Zener diodes 24 and 26 are connected in series to the junction of voltage multiplier 20 and capacitor 22 through resistor 28 and to the emitter 30 of transistor switch 32. The collector 34 of transistor 32 is connected to the gating terminal 36 of silicon controlled rectifier 38. The anode of SCR 38 is connected to the junction of capacitor 22 and multiplier 20 and the cathode is grounded. The primary winding 40 of ignition coil 42 extends between ground and the other terminal of capacitor 22. Thus, when a gating signal is transmitted to the SCR (across transistor 32) a circuit is completed enabling capacitor 22 to discharge across the coil primary winding. The base 44 of transistor switch 32 is connected to the nongrounded contact 16 through resistor 46 and to ground through resistor 48 so that when the breaker points open the transistor will turn ON and when the points close, the transistor will turn OFF.
In operation, when the breaker points are closed, the base of transistor 32 is grounded and no current flows through the transistor. Hence, the SCR does not receive the necessary gating signal to conduct and remains OFF. When the points separate (that is, when the engine timing cam causes the breaker points to open) the transistors 32 is turned ON and will conduct. The Zeners 24 and 26 conduct when the charge on capacitor 22 builds to the avalanche level of the Zeners, which when transistor 32 is ON, gates SCR 38 and thereby allows the capacitor 22 to discharge across the primary winding 40 of coil 42, inducing a high-voltage surge in the secondary winding 50 of coil 42. The high voltage surge causes a spark across the gap of the appropriate spark plug 52 through distributor 54. The reverse surge of current through SCR 38 from the coil primary, turns the SCR OFF, and, as long as the breaker points of the engine timer remain open, the capacitor 22 will recharge and the process will repeat itself, producing a series of sparks during the time that the points remain open. The frequency at which the sparks are produced is determined by the relationship between the high DC voltage of the voltage multiplier unit 20, the breakdown voltage of Zeners 24 and 26, the value of capacitor 22, as well as the values of resistor 28 and the ignition coil. It has been experimentally found that a frequency of approximately 2,000 sparks per second provides the most beneficial results.
Having thus described the invention, what is claimed is:
1. A solid state automotive ignition system adapted to provide a series of relatively short duration short voltage rise time sparks for ignition purposes during each successive ignition period comprising:
a voltage source having a power terminal and a ground terminal;
engine timer means including a pair of breaker-points the separation of which defines the beginning of said ignition period, said breaker-points having one grounded contact and one nongrounded contact;
a capacitor connected in series with said voltage source power terminal and one end of the primary winding of an ignition coil, the other end of said primary winding being grounded;
a secondary winding of said ignition coil coupled to said primary winding for producing a spark upon the discharge of said capacitor across said primary winding;
a silicon controlled rectifier having an anode, a cathode, and a gate, said anode being connected to the junction of said voltage source and said capacitor, said cathode being grounded and said gate being connected to a gate signal source through a switch; zener diode means having a cathode connected to said voltage source-capacitor junction and an anode connected to said switch, and adapted to break down when the charge on said capacitor attains a predetermined level; and
switch means adapted to turn ON when said breaker-points separate.
2. The invention in accordance with claim 1 wherein said switch means comprises a transistor having a base connected to the nongrounded breaker-point contact, a collector connected to said zener anode, and an emitter connected to said SCR gate.