| 摘要 |
PURPOSE:To obtain good operating performance in the whole revolving area of the engine by a method wherein the valve timing of at least one cam of valves is displaced in accordance with the revolving speed of the engine equipped with a plurality of suction and exhaust valves per one cylinder. CONSTITUTION:In the engine wherein respective cylinders 2, 3 are provided with a pair of suction ports and the suction ports are equipped with respective suction valves 13a-13d while the suction valves are opened and closed by a suction cam mechanism C, the cam shaft 21 of the suction cam mechanism C is constituted of the fixed cams 22, 23, pushing respective suction valves 13a, 13b and integral with the cam shaft 21, and a movable cam 24, pushing the other suction valves 13c, 13d and fitted to the outside of the cam shaft 21. Slanted grooves 26a, 26b are formed at the central section of the movable cam 24 and the cam shaft 21 is formed with axial grooves 27a, 27b while a guide pin 29, common for both grooves, is engaged with both grooves. The guide pin 29 is displaced axially by the effect of a centrifugal weight 39 through a sliding sheave 37 and a rod 38 whereby the opening degree of the suction valves 13c, 13d may be regulated. |
