| 摘要 |
PROBLEM TO BE SOLVED: To prevent generation of unburned HCs and dilution of lubrication oil by closing an exhaust valve before an intake top dead center, while opening the intake valve after the intake top dead center and injecting fuel in the vicinity of the intake top dead center, when the exhaust valve and the intake valve are closed. SOLUTION: An exhaust valve is closed before an intake top dead center TDC, while an intake valve is opened when a pressure inside a combustion chamber is equalized to that inside an intake port after passage through the intake top dead center TDC, and fuel injection is carried out in the vicinity of the intake top dead center TDC in which the exhaust valve, and the intake valve are closed. In this process, the combustion chamber is filled with a high temperature burnt gas because the intake valve is closed, so that fuel particle diameter becomes small. Since the exhaust valve is closed before the intake top dead center TDC, a pressure inside the combustion chamber is increased, so that the injected fuel is hardly dispersed. Therefore, the adhesion of fuel particles to the fuel combustion chamber wall face is prevented. While a piston is lowered subsequently, a fuel evaporation action is promoted, and adhesion of fuel to the inside wall is reduced also in this process. Consequently, generation of unburned HC and dilution of lubrication oil can be deterred.
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