Patent ID: 8276554

Claim:
A spark ignition type internal combustion engine comprising: a variable compression ratio mechanism able to change a mechanical compression ratio; a variable valve timing mechanism able to control a closing timing of an intake valve, and a controller that is configured to control the variable compression ratio mechanism and the variable valve timing mechanism so that: the mechanical compression ratio is made higher at an engine low load operation side than at a time of engine high load operation, the mechanical compression ratio is gradually reduced at an engine high load operation side as the engine load becomes higher, a first combustion by a first air-fuel ratio and a second combustion by a second air-fuel ratio larger than the first air-fuel ratio are selectively performed, the first combustion is performed under the first air-fuel ratio at the high load operation side, and at the engine low load operation side, the second combustion is performed by the second-air fuel ratio when the mechanical compression ratio is lower than a predetermined reference value, and the first combustion is performed by the first air-fuel ratio when the mechanical compression ratio is higher than the predetermined reference value.