| 摘要 |
PURPOSE:To reduce the flow resistance of suction and exhaust by forming oval suction/exhaust ports and rotating the suction/exhaust valve around the axis when lifting said valve. CONSTITUTION:The umbrella section and the suction port 20 of a suction valve 19 are formed oval while a screw 18 is provided such that the valve 19 will rotate around the axis when the valve 19 is driven by the cam 16 and lifts. Consequently, upon lifting of the valve 19, the umbrella section of valve and the suction port 20 are shifted through relative rotation. Since the suction air will flow directly into the combustion chamber without hindrance of umbrella section, the area will be increased to reduce the flow resistance resulting in improvement of suction efficiency. This arrangement can be employed in the exhaust valve to improve the exhaust efficiency. |
