| 摘要 |
PURPOSE:To perform optimum suction in a wide operating range of an engine, by installing two suction passages, short large diametral one for high-speed use and long small diametral one for low-speed use, in parallel, and closing the high- speed suction passage in time of driving at low speed, while controlling the on-off timing of a suction valve as well. CONSTITUTION:Two suction valves are installed in one cylinder, connecting a large diametral suction pipe 6A to each, and a valve 7A to be closed in time of low speed is installed in each of them. Small diametral, long suction pipes 18 are installed in one of large diametral suction pipe 6A. A suction valve 4c makes on-off timing controllable by a control unit. And, in time of low engine speed, the valve 7A is closed and suction takes place with only a low-speed suction passage 18, securing an optimum suction inertial effect, while closing timing of the suction valve is delayed to some extent. In time of engine high speed, the valve 7A is opened, securing a large quantity of suction air at the specified inertial effect, while openeing timing of the suction valve is accelerated, thus suction efficiency is improved. |
