| 摘要 |
PROBLEM TO BE SOLVED: To effectively reduce a tapping sound (keying sound) in an initial stage and a latter stage of recovery operation over a long period of time in a negative pressure type booster.SOLUTION: A negative pressure type booster contains, in an axial hole 22a of a valve body 22, a valve mechanism V which is composed of a negative pressure valve for connecting and blocking a negative pressure chamber R1 and a pressure change chamber R2 according to the reciprocation of a plunger 32 to the valve body 22 and an atmosphere valve for connecting and blocking the pressure change chamber R2 and the atmosphere. The plunger 32 and a key member 39 are assembled in the axial hole 22a. The booster keeps valve body 22 in a forward moving position and contains a projection 22e for holding the key member 39 so as to be inclined with respect to the valve body 22 when it is situated in the forward moving position and the plunger 32 is moved backward from the forward moving position. |
