| 摘要 |
<P>PROBLEM TO BE SOLVED: To restrain generation of operation noise accompanied by operation of a pressure reduction valve in a hydraulic booster wherein the pressure reduction valve opening and closing in accordance with retreating and advancing of a control piston actuating reaction force based on a hydraulic pressure of a booster hydraulic chamber along the retreating direction through a reaction force piston intervenes between a release chamber and a hydraulic pressure control chamber. <P>SOLUTION: A pressure reduction valve seat 146 is provided on the reaction force piston 92 equipped with a small diameter piston part 92a of which front end faces the booster hydraulic control chamber 130, and a large diameter piston part 92b coaxially and integrally continued to a rear end of the small diameter piston part 92a through an annular step part 92c facing the booster hydraulic control chamber 130 side. A pressure reduction valve element 147 whose spring is energized to the pressure reduction valve seat 146 side while the rearmost position is regulated is housed in the booster hydraulic control chamber 130, and an inner peripheral part of an elastic member 127 through which the small diameter piston part 92a of the reaction force piston 92 is liquid-tightly and slidably inserted is arranged in such a manner of confronting the annular step part 92c so as to be deformed and pushed to the annular step part 92c when the hydraulic pressure of the booster hydraulic control chamber 130 is equal to or more than the predetermined pressure. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
