Reverse rotation detector for internal combustion engine

摘要

A crank angle sensor outputs a pulse signal whenever a crankshaft rotates a predetermined angle. An ECU performs an elimination process on a sequence of pulse signals to obtain a remaining signal used to determine the crank angle. When the rotation speed of the crankshaft becomes lower than a predetermined threshold, the ECU suspends the elimination process and determines the crank angle using pulse signals that have not undergone the elimination process. The ECU detects reverse rotation of the crankshaft based on pulse signals that have not undergone the elimination process. A crank counter is operated in synchronism with the falling of a pulse signal when the crankshaft rotates in the forward direction and is operated in synchronism with the rising of a pulse signal when the crankshaft rotates in the reverse direction.