Spark ignition type internal combustion engine

Abstract

In an internal combustion engine, a variable compression ratio mechanism (A) able to change a mechanical compression ratio and a variable valve timing mechanism (B) able to control the closing timing of an intake valve (7) are provided. The mechanical compression ratio is held at a maximum mechanical compression ratio at the engine low load operation side and gradually made to decrease as the engine load increases at the engine high load operation side. Combustion is performed by a stoichiometric air-fuel ratio at the engine high load operation side, and combustion is performed by a lean air-fuel ratio at the engine low load operation side where the mechanical compression ratio becomes the maximum mechanical compression ratio.

Description

technical field [0001] This invention relates to spark ignition internal combustion engines. Background technique [0002] A spark ignition type internal combustion engine is known (for example, refer to Japanese Patent Application Laid-Open No. 2004-218522 ): a variable compression ratio mechanism capable of changing the mechanical compression ratio and a variable valve timing mechanism capable of controlling the closing timing of the intake valve. Timing mechanism (variable valve train), and when the internal combustion engine is operating at a medium load and when the internal combustion engine is operating at a high load, the supercharging effect of the supercharger is performed, and when the internal combustion engine is transformed from high load operation to medium load operation, it is used The mechanical compression ratio is increased and the closing timing of the intake valve is retarded as the engine load decreases in a state where the actual compression ratio is ...

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However, the above-mentioned literature has no mention of this aspect

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