| 摘要 |
An internal combustion engine (1) has a variable compression ratio mechanism (2) using a multi-link piston crank mechanism, and is equipped with a fuel injection valve (8) that injects fuel into the cylinders. The variable compression ratio mechanism changes the compression ratio by moving the top dead center position of the piston (24) up or down. During a high load the fuel injection period increases, but with the present invention the target compression ratio becomes a low compression ratio during a high load, and the fuel injection start timing is before the exhaust top dead center, so the fuel injection period straddles the exhaust top dead center. When the compression ratio is low (characteristic 'b') the distance between the fuel injection valve and the crown surface of the piston (24) near the top dead center increases as indicated by the symbol 'H', so even if the injection occurs near the top dead center smoke is not easily generated, and the injection period can be lengthened to straddle the top dead center. Accordingly, a fuel injection valve with a small injection rate can be used. |
