| 摘要 |
PURPOSE:To simplify the changing operation of valve timing in a variable valve timing device for intake and exhaust valves in an engine, by incorporating both high and low cam shafts on one cam shaft holder, and as well by making the holder swingable so that the valve timing is changed. CONSTITUTION:A low speed cam shaft 3a alone acts to a rocker arm 2 when a cam shaft holder 4 is swung upward upon engine low speed, thereby the valve 1 is operated to carry out the action along the characteristic curve denoted by (b). Then the vlave shaft holder 4 is swung downward in order to change the valve timing into that for high speed, so that a high speed cam shaft 3b is gradually moved down to a position where the high speed cam shaft 3b acts to the rocker arm 2. Thus, the oening and closing of the valve 1 are controlled by the cam shaft 3b so that the valve follows the characteristic curve denoted by (a). With this arrangement, the valve timing may be changed by a simple operation. |
