US Patent 7617673 Controller for internal combustion engine

A start-up assisting degree by a motor is set at an appropriate level on the basis of a catalyst condition represented by a catalyst temperature, an oxygen storage (degree) in the catalyst, a change in combustion control represented by an air-fuel ratio for combustion, an ignition timing, or an engine condition such as an engine stopping time period, an engine cooling water temperature, a crank stopping position or rotational load.