Patent ID: 8688359

Claim:
A control device for an idle stop system of a type in which fuel injection is stopped when an idle stop condition is satisfied during engine operation, and a pinion gear is engaged with a ring gear coupled to a crank shaft of an engine during an engine inertial rotation period until an engine rpm becomes zero, wherein the idle stop system includes: a ring gear rotational speed detection unit that detects a rotational speed of the ring gear; a crank angle detection unit that detects a crank angle of a crank shaft of the engine; and a pinion rotational speed detection unit that detects a rotating speed of the pinion, and wherein the control device estimates a future engine rotational speed on the basis of the ring gear rotational speed detection unit and the crank angle detection unit, and controls a pushing timing of a pinion pushing unit taking a delay of the pinion pushing unit into consideration so that the pinion contacts the ring gear when there is a given speed difference between a pinion rotational speed obtained by converting the pinion rotational speed based on the pinion rotational speed detection unit taking a reduction ratio of the pinion to the ring gear into consideration, and the rotational speed of the ring gear.