| 摘要 |
<P>PROBLEM TO BE SOLVED: To secure high net thermal efficiency by using a first air-fuel ratio of high thermal efficiency at an engine heavy load operation side and using second air-fuel ratio of high thermal efficiency at an engine light load operation side. <P>SOLUTION: An internal combustion engine has a variable compression ratio mechanism A capable of changing a mechanical compression ratio and also has a variable valve timing mechanism B capable of controlling timing of closure of an intake valve 7. At the engine light load operation side, the mechanical compression ratio is maintained at the maximum mechanical compression ratio, and at the engine heavy load operation side, the ratio is gradually reduced with an increase in the engine load. Combustion at a theoretical air-fuel ratio is taken place at the engine heavy load operation side, and combustion at a lean air-fuel ratio is taken place at the engine light load operation side where the mechanical compression ratio is at the maximum mechanical compression ratio. <P>COPYRIGHT: (C)2009,JPO&INPIT |
