| 摘要 |
PROBLEM TO BE SOLVED: To provide an engine provided with a charge air discharge type air fuel ratio control device suppressing fluctuation of air fuel ratio, enabling accurate air fuel ratio control, and preventing breakage of a main charge air discharge valve with accompanying chattering by reducing pressure loss of the main charge air discharge valve and preventing chattering (minute vibration) of the main charge air discharge valve in a heavy load operation area where charge air discharge quantity is not much and opening of the main charge air discharge valve is low. SOLUTION: In the engine constructed to control air fuel ratio of the engine by adjusting opening of the main charge air discharge valve adjusting passage area of a charge air discharge passage branched off from a middle of a charge air passage connecting a compressor of a supercharger and the engine, an auxiliary charge air discharge valve is installed in an outlet side of the main charge air discharge valve of the charge air discharge passage in series, a discharge valve controller controlling opening of the main charge air discharge valve according engine operation conditions including engine load of the engine, and the auxiliary charge air discharge valve is constructed to be set to predetermined opening with being separated from control by the discharge valve controller. COPYRIGHT: (C)2008,JPO&INPIT
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