| 摘要 |
PURPOSE:To reduce start load by providing a pressure chamber of a substantially closed-up space between a spool valve and a stopper and having the pressure chamber serving as a pneumatic spring if a pressure is applied to the back of the spool valve, so as to take longer period for travel of the spool valve. CONSTITUTION:A front housing 5 includes a cylinder part 17 slidably supporting a brass spool valve 101 of an opening and closing means for two by-pass port 100 which communicates a compressing chamber R and an intake chamber 10 with each other. A stopper end 18a is inserted in the cylindrical pressure chamber 102 which is formed inside the spool valve 101 while a spring 19 is disposed between the flange part 18b formed at the rear end of the stopper 18 and one end 101a of the spool valve in order to push the spool valve 101 against the other end 101b thereof. If a pressure is applied on the back face of the spool valve 101, the pressure chamber 102 functions as a pneumatic spring and prolongs the period required for the movement of the spool valve 101, thereby reducing the start load. |
