System to prevent reverse engine operation

Abstract

An ignition system for an internal combustion engine, such as an outboard marine engine, which includes an advanced timing schedule, a non-advanced timing schedule, and a circuit for switching between the two schedules or disabling both schedules based upon engine operating conditions. The ignition system includes an opto-electronic time base generator which produces two sets of timing pulses relative to crankshaft position which are non-advanced timing pulses and advanced timing pulses. The time base generator comprises two LED-phototransistor pairs and an encoder disk attached to the crankshaft with slots to interrupt the radiation path between each LED-phototransistor pair. The encoder disk is provided with a synchronizing slot, multiple timing slots associated with the cylinders of the engine, and an direction slot. The direction of the rotation of the engine can be sensed by the spatial relationship between the synchronizing slot and the direction slot. The non-advanced pulses are generated based upon the trailing edge of each timing slot while the advanced pulses are generated based up the leading edge, wherein the width of the timing slots indicate the degree of advancement of the advanced schedule over the non-advanced schedule. Both schedules are inhibited based on predetermined operating parameters of the engine or the detection of a reverse engine operation.