| 摘要 |
PURPOSE:To increase the scavenging efficiency and improve combustion perfor mance by lowering the intake pressure in the operation region in which the engine revolution speed is low, in the constitution in which the exhaust gas is scavenged by selecting the previously set overlap time according to the opera tion state. CONSTITUTION:Two suction ports 5 and 6 opened and closed by the suction valves 3 and 4 are formed onto each combustion chamber 2 of an engine 1, and the opening/closing timing is set so that each valve opening timing of the first suction valve 3 and an exhaust valve is hardly overlapped. While, the opening/closing timing is et so that each valve opening timing of the second suction valve 4 and the exhaust valve is overlapped, and the overlap quantity is set so that the proper scavenging effect can be obtained in the standard operation state in the low revolution high load operation region of the engine 1. In the operation region in which the engine revolution speed is low in comparison with that in the standard operation state, a control valve 15 in a communication passage 14 is closed, and the intake pressure is lowered by the intake inertia effect.
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