COMPRESSED SELF-IGNITION GASOLINE ENGINE

摘要

PROBLEM TO BE SOLVED: To suppress occurrence of instable combustion or knocking in a low load operation area, at the changeover time between spark ignition combustion operation and compressed self-ignition combustion operation. SOLUTION: A uniform spark ignition combustion operation state under extremely low load is changed over with a uniform compressed self-ignition combustion state under appropriately low load, and vise versa. A closed timing is provided at the changeover time, where both an intake and an exhaust valves are closed near a compression top dead center by means of a variable opening/ closing time means. The compressed self-ignition combustion is started after performing the spark ignition combustion under a stratified charge state in which fuel injection is performed during compression stroke. In the compressed self-ignition combustion, fuel injection is first performed during the closed timing.