Patent ID: 8573166

Claim:
A spark ignition type internal combustion engine comprising a variable compression ratio mechanism which can change a mechanical compression ratio and a variable valve timing mechanism which can control a closing timing of an intake valve, wherein a no-entry region for a combination of a mechanical compression ratio, a closing timing of an intake valve and an intake air amount is set, an operating point showing the combination of the mechanical compression ratio, the closing timing of the intake valve and the intake air amount is prohibited from entering the no-entry region regardless of an operating state of the engine, the no-entry region has a broadest region at the time of a minimum intake air amount and gradually becomes smaller as the intake air amount increases, a no-entry layer is set which extends along an edge of the no-entry region at the time of the minimum intake air amount and which extends from the no-entry region toward an intake air amount increase side while surrounding the no-entry region as the intake air amount increases from the minimum intake air amount, said operating point is prohibited from entering the no-entry layer when the demanded intake air amount is made to decrease and said operating point moves toward the no-entry region, and thereby said operating point is blocked from entering the no-entry region.