| 摘要 |
PROBLEM TO BE SOLVED: To provide a spark ignition type internal combustion engine exhibiting high thermal efficiency. SOLUTION: This spark ignition type internal combustion engine has a variable expansion ratio mechanism A which can alter the mechanical expansion ratio, and an exhaust variable valve mechanism C which can alter the timing for opening an exhaust valve 9. The mechanical expansion ratio and the timing for opening the exhaust valve are set depending on an engine load such that the mechanical expansion ratio increases and the timing for opening the exhaust valve is retarded to the exhaust bottom dead center as the engine load decreases. By setting the mechanical expansion ratio in such a manner depending on the engine load, the thermal efficiency can be enhanced as compared with a case where the mechanical expansion ratio is set to make the actual compression ratio constant, for example. COPYRIGHT: (C)2009,JPO&INPIT |
