Rotary direction sensor for engine ignition control

Abstract

A rotary direction sensor used in conjunction with an engine spark ignition system is disclosed. Two sensors are used to sense the rotational position of a rotary body which is being synchronously rotated by the crankshaft of an internal combustion engine. Output signals of the sensors are compared by a logic circuit which produces ignition spark timing signals in response to the rotation of the rotary body in a predetermined direction. These spark timing signals are subsequently used to trigger SCRs which apply a high voltage across an ignition coil and thereby cause an ignition spark in a cylinder of the internal combustion engine. The sensors, the rotary body and the logic circuit are constructed so that engine spark timing signals are only produced for the internal combustion engine when the rotary body is rotated in a given rotary direction. Thus the generation of cylinder spark ignitions when the engine is being rotated in a reverse direction is inhibited. The direction of rotation of the rotary body is sensed by the logic circuit comparing the logic state of the signal produced by one of the sensors with the polarity of a logic state transition of the signal produced by the other sensor. Thus spark timing control signals are produced in response to the coincidence of a predetermined logic state of one sensor signal with a predetermined polarity transition of another sensor signal.