| 摘要 |
PURPOSE:To enable to obtain a high charging efficiency at the time of a high-speed high-load operation of an engine while facilitaing manufacture, by a method wherein the axis of an intake port at the time of opening a rotary valve is set to be in the form of a straight line passing through an intake valve system, and the cross-sectional area of the port is set to be uniform. CONSTITUTION:At the time of the high-speed high-load operation wherein intake air quantity is large, the roatry valve 25 is opened, so that an intake mixture in a passage part A is divided into three portions. The first portion is a mixture flow which enters between side wall surfaces 14a and 17 and swirls along an upper wall surface 20, the second portion is a mixture flow which flows into a helical part B by passing along a branch passage 24, and the third portion is a mixture flow which flows into the helical part B by passing along a bottom wall surface 21. Since the flow resistance in the branch passage 1 is smaller than that for the first mixture flow, the quantity of the second flow is larger than that of the first flow. Further, the direction of the first flow swirling in the helical part B is deflected downward by the second flow, and the swirling force thereof is weakened. Accordingly, since the quantity of the mixture flowing through the branch passage 24 with small flow resistance is increased and the direction of the first flow is downwardly deflected, a high charging efficiency can be obtained. |
