| 摘要 |
A valve mechanism for brake booster, in particular, of a brake booster which is provided with a mechanism for reducing a lost stroke, includes a first valve seat on which a plurality of tabs are formed, with communication areas being defined by spaces left between adjacent tabs. When the brake booster is inoperative, if the first valve seat moves close to the valve element such that the latter may be seated upon the first valve seat, the tabs abut against the valve element to assure a reliable communication between the inside and the outside of the first valve seat by means of the communication areas. When the booster is inoperative, the tabs are embedded in the valve element to block or interrupt the communication through the first valve seat. In the conventional practice, the design has been to minimize the lost stroke to the extent that the valve element cannot be seated upon the first valve seat when the booster is inoperative. But, according to the invention, if the valve element gently contacts the first valve seat, the communication area reliably maintains the communication through the first valve seat, thus allowing the lost stroke to be reduced in comparison to the prior art arrangement.
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