| 摘要 |
PURPOSE:To enhance the scavenging effect and improve the combustibility by providing a first suction port having a short overlap open period with respect to an open period of an exhaust port, providing a second suction port having a long overlap open period with respect to the open period of the exhaust port, and inducing the air from both the suction ports under at least a high load. CONSTITUTION:First and second suction ports 3 and 4 are formed to open into a combustion chamber 2 of an engine 1, and are connected to first and second suction passages 6 and 7, respectively. An overlap period between an open period of the second suction port 4 and an open period of exhaust valves 13 is set to be longer than an overlap period between an open period of the first suction port 3 and the open period of the exhaust valves 13, and can be changed according to an engine operational condition. Such change is effected by rotating a worm gear 24 by means of a drive motor 22. A fuel injector 9 is provided in the first suction passage 6 at a upstream position of the suction port 3, and a control valve 10 is provided in the second suction passage 7 at a upstream position of the suction port 4. Both the suction passages 6 and 7 are joined at the upstream side of the fuel injector 9 and the control valve 10 to a suction passage 14. A mechanical supercharger 18 is provided downstream of a throttle valve 15 in the suction passage 14.
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