Patent ID: 8302569
Filing Date: 2012-11-06
Classification: F01L,F02B,F02D,Y02T

Abstract:
1. A spark-ignited internal combustion engine comprising: a variable compression ratio mechanism that changes a mechanical compression ratio, which is obtained by dividing a sum of the volume of a combustion chamber when a piston is at a compression top dead center and a piston displacement by the volume of the combustion chamber; a throttle that regulates the amount of intake air that is supplied into the combustion chamber; and an actual compression start timing-changing mechanism that changes a start timing at which an actual compression starts, wherein a maximum mechanical compression ratio while the engine is in operation is reduced with increase in engine speed, wherein the actual compression start timing-changing mechanism is a variable valve timing mechanism that controls a valve closing timing of the intake valve, wherein the amount of intake air that is supplied into the combustion chamber is controlled by changing the valve closing timing of the intake valve, wherein the valve closing timing of the intake valve is shifted away from an intake bottom dead center when the maximum mechanical compression ratio is reduced, and wherein when the maximum mechanical compression ratio is reduced, the valve closing timing of the intake valve is shifted away from the intake bottom dead center within a range defined by a limit valve closing timing that gives a limit within which the amount of intake air that is supplied into the combustion chamber can be controlled, and when the amount of intake air that is supplied into the combustion chamber is still greater than the amount of intake air that corresponds to an engine load, the throttle valve is driven in a valve-closing direction.