Transistorized ignition apparatus for driving ignition coils in an internal combustion engine

Abstract

A transistorized ignition apparatus for driving plural ignition coils of an internal combustion engine comprising two power transistor circuits, each having a power transistor, and a pick-up coil for generating an ignition timing signal synchronized with the rotation of the engine. A wave-form shaping circuit receives the ignition timing signal and determines the conduction period of the power transistors, including the conduction starting point thereof. Two driver circuits, which are provided for respective power transistor circuits, produce driving signals thereto on the receipt of an output from the wave-form shaping circuit. Each power transistor circuit has a current limiter circuit which decreases the base current of the power transistor depending on the amount of the current flowing therethrough. The currents through the power transistors, therefore, are restricted to respective maximum values and the operations thereof are drawn into the non-saturation region. One maximum value is preset lower than the other. A feedback circuit monitors the voltage at the collector of the power transistor, the current through which is restricted under the lower maximum value, and detects the duration of the non-saturated operation thereof. In the wave-form shaping circuit, the conduction period of the power transistors, particularly the conduction starting point, is controlled depending on the output from the feedback circuit.

Dependencies are inferred from the claim text.