Internal combustion engine system, control method of internal combustion engine system, and power output apparatus

Abstract

At a time of stopping operation of an engine, after elapse of a preset time period since start of self-sustaining operation of the engine at a stop rotation speed Nstop, the drive control sets a torque command Tm* of a motor MGto a rotation speed-decreasing, vibration-suppressing torque and starts decreasing a rotation speed Ne of the engine (steps S, S, S, S, and S). The rotation speed-decreasing, vibration-suppressing torque is set to smoothly decrease the rotation speed of the engine and suppress the potential vibration caused by the decreased rotation of the engine. A correction torque Tmod is set based on a crank angle CA and an engine water temperature Tw at the rotation speed Ne of the engine decreasing to a preset reference speed Nref (step S). The torque command Tm* of the motor MGis then set by adding the set correction torque Tmod to the rotation speed-decreasing, vibration-suppressing torque (step S). This arrangement effectively prevents the crank angle CA from exceeding a top dead center immediately before the stop of the engine and thereby suppresses the potential vibration causes by the excess of the crank angle CA over the top dead center.