SPARK IGNITION TYPE INTERNAL COMBUSTION ENGINE

摘要

A spark ignition type internal combustion engine comprises a variable compression ratio mechanism, a variable valve timing mechanism, and an air flow control valve e.g. a swirl control valve, a throttle valve or a tumble valve for example. The mechanical compression ratio is made maximum at engine low load operation and the actual compression ratio is made substantially the same as that at of engine medium and high load operation. When the engine load is in an extremely low load region, the air flow control valve is used to control an amount of intake air fed into the combustion chamber. Due to this, a high heat efficiency can be realized even in a region where the amount of intake air is difficult to control by changing the closing timing of the intake valve.