| 摘要 |
PURPOSE:To reduce the friction loss at cam-shaft part by permitting the spring load of a valve spring to be varied by varying the position of a spring retainer according to the engine operation state. CONSTITUTION:The second spring retainer 13 is installed in the intermediate part between the first spring retainer 5 fixed at a valve edge part and the base seat part 6 of a cylinder head 1, and valve springs 7A, 8A, 7B, and 8B are installed in two stages. A rotary stopper 16 is installed which fixes the second spring retainer 13 at a lower position 18A or at a higher position 18B only in case when the valve is opened, and said stopper 16 is turned in accordance with the engine operation state. By the constitution in which the spring load is reduced in the lower speed range than in the higher speed range, the lubrication state of a cam-shaft part is improved without deteriorating the tappet valve function, and the friction loss can be reduced. |
