Solid state ignition system

Abstract

The solid state ignition system accurately controls the maximum primary winding current over a large range of operating voltages and selectively reduces its power consumption in response to a preselected ignition condition. The system includes an ignition transformer having a primary winding connected in series with a current regulator and a secondary winding connected with an igniter device for igniting an air-fuel mixture. A Darlington transistor is connected in series with the primary winding for blocking and permitting the flow of electrical current through the primary winding. A current regulating oscillator which controls the Darlington transistor alternately causes the transistor to be biased conductive and nonconductive. A comparator which is connected with the current sensor for sensing the primary winding current compares the sensed primary current with a preselected current. In response to the sensed current meeting or exceeding the preselected current, the comparator causes the current regulating oscillator to cause the transistor to block current flow. A current reducing circuit is connected with the current regulating oscillator to cause the current regulating oscillator to hold the transistor nonconductive intermittently in response to a sensed combustion condition. In this manner, the primary winding current is limited to a preselected magnitude without regard to the magnitude of the voltage from the voltage regulator and the average primary winding current is reduced in response to the combustion condition.