Patent ID: 8417437

Claim:
A control method of an engine which has a homogeneous-charge-compression-ignition combustion mode in which a premixed air-fuel mixture is compressed in a combustion chamber so that a self-ignition of the mixture is performed without requiring spark from a spark plug, and a minus valve overlap period during which an intake valve and an exhaust valve are both closed at a transitional time from an exhaust stroke to an intake stroke, the method comprising: determining a high-engine load range where an engine load is higher than a specified load in the homogeneous-charge-compression-ignition combustion mode; executing a first fuel injection from a fuel injector in said high-engine load range at a point when an internal pressure of the combustion chamber drops below a specified pressure after the top dead center of the exhaust stroke during the minus valve overlap period; executing a second fuel injection from the fuel injector in said high-engine load range at a point after an execution timing of said first fuel injection; determining a low-engine load range where the engine load is lower than said specified load in the homogeneous-charge-compression-ignition combustion mode; executing a first fuel injection from the fuel injector in said low-engine load range at a point before the top dead center of the exhaust stroke during the minus valve overlap period; and executing a second fuel injection from the fuel injector in said low-engine load range at a point after an execution timing of said first fuel injection.