Combustion control apparatus for engine

A combustion control apparatus for an engine having a spark plug, a fuel injector for supplying fuel to a combustion chamber and a variable valve timing mechanism capable of varying valve timings of an exhaust valve and an intake valve, comprising:

• a combustion mode establishing means for establishing a combustion mode to either of at least following two modes, a compression ignition combustion mode and a two-cycle spark ignition combustion mode according to an operational area of said engine;
• and
• a valve timing establishing means for establishing said valve timings of said exhaust and intake valves so as to form a negative overlap period in which said both exhaust and intake valves concurrently close in the neighborhood of the exhaust top dead center, when said combustion mode is established to said compression ignition combustion mode and for establishing said valve timings of said exhaust and intake valves so as to carry out a gas exchange once per one revolution of said engine, when said combustion mode is established to said two-cycle spark ignition combustion mode.