| 摘要 |
<p>PURPOSE:To prevent structural components from the reduction of their mechanical lives and the occurrence of breakages by engaging a freely projecting and retreating cam follower with the side cam of a end journal section to shift axially a cam shaft. CONSTITUTION:In a variable valve timing device 1, a cam shaft 2 is formed over the whole periphery of the end journal section 2a with side cams 8, 9 respectively for high and low speed change-over. Piston pins 14a, 15a acting as cam followers treating projecting from and retreating in and a bearing section 7 for supporting an end journal section 2a are provided. Piston pins 14a, 15a operated by hydraulic cylinder mechanisms 14, 15 are engaged with side cams 8, 9 to move axially the cam shaft 2. Thus, during one rotation of the cam shaft 2, the cam shaft 2 can be instantly and largely moved. Then, the occurrence of excessive contact surface pressure between valve opening and closing cams 3H, 3L, 4H and 4L and rocker arms 19, 20 can be restrained.</p> |
