Eltra Corporation

Andrew T Tershak

Ignition pulses are supplied to an internal combustion engine from a breakerless electronic ignition system wherein the ignition pulses are produced in response to the movement of teeth on an electrically conductive trigger wheel past an inductive sensor. The inductive sensor is part of a LC tank circuit of an oscillator normally producing an oscillatory output signal which is detected by a bistable demodulator, and as a tooth moves into close proximity with the inductive sensor energy from the tank circuit is lost through an inductive coupling with the trigger wheel until the oscillatory output signal is terminated. The bistable demodulator responds to the absence of an oscillatory output signal by producing a timing signal which causes an ignition pulse to be supplied to the engine. The trigger wheel rotates in synchronization with the engine, and the initial timing of the ignition system is determined by setting the relative positions of the sensor and the trigger wheel. To advance or retard the initial timing of the ignition system, a resistor is connected across the tank circuit by a controllable switch to control the energy level in the tank circuit and hence the time required to terminate the oscillatory output signal. The initial timing of the ignition system may be set with the resistor electrically connected across the tank circuit, and upon the occurrence of engine conditions may result in undesirable ignition knock the controllable switch may be rendered nonconductive so as to retard the timing of the ignition pulses. Alternatively, the initial timing of the ignition system may be set with the resistor electrically connected across the tank circuit so that under certain engine operating conditions the switch may be rendered conductive to advance the initial timing of the ignition system. The switch connecting the resistor across the tank circuit may be a transistor which is rendered fully conductive or nonconductive by control signals produced according to predetermined engine operating conditions, or alternatively the conduction of the transistor may be gradually varied from fully conductive to nonconductive so as to serve as a variable resistor gradually increasing or decreasing the resistance across the tank circuit and thereby gradually advancing or retarding the initial timing of the ignition system.

Breakerless electronic ignition system

The timing of ignition pulses supplied to an engine is controlled in accordance with a plurality of different operating conditions of the engine to minimize undesirable exhaust pollutants. As the speed of the engine increases from a cranking speed toward an idling speed, the ignition pulses are produced in synchronism with reference timing signals indicating movement of a piston to a top dead center position in a combustion chamber, and upon further increases in engine speed the ignition pulses are produced in synchronism with advanced timing signals generated by an electronic advance means in accordance with the approximate instantaneous position of the piston in the combustion chamber and selected engine operating conditions. The control of the timing of the ignition pulses is transferred between the two different timing signals by a selector means operating in response to control signals indicative of engine speeds above or below a predetermined speed. The control signals are produced by control means in accordance with a speed signal generated in response to the reference timing signals and compared with a reference signal representative of the predetermined speed. To prevent an ignition pulse from being interrupted by changing control signals, the selector means includes a signal processor which responds to the control signals only in accordance with a clock pulse supplied in time lagging relation to the reference timing signals used in producing the control signals.

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Evansville, IN, United States of America

Andrew T Tershak