| 摘要 |
PURPOSE:To reduce the number of natural oscillation of a valve body and to inhibit occurring of a noise, by constituting the valve body with a valve head which opens and closes a one side valve opening and rodlike stays provided on both sides of the valve head so that they form a straight line each other. CONSTITUTION:A valve body 19 is formed of a valve head 19a which opens and closes a valve opening 17 of a negative pressure type clutch strength doubling device 7 side and rodlike stays 19b and 19c provided on both sides of the valve head 19a so as they form a straight line each other. The valve body 19 is oscillated through a pulsation of gas according to an opening and closing operation of the valve opening 17, but the number of natural oscillations are reduced as mass of the valve body 19 is increased by that of stays 19b and 19c, and generation of a hitting sound resulting from collision of the valve body 19 with the circumferential surface of a chamber 16 can be inhibited by setting up the stays in a region where noise is not affected badly. |
