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 booster hydraulic control chamber. <P>SOLUTION: The reaction force piston 92 is provided with a pressure reduction valve seat 146 constituting a part of the pressure reduction valve 117, and a through hole 144 for communicating the booster hydraulic control chamber 130 with the release chamber 135 at the time of opening of the pressure reduction valve 117. A variable restriction mechanism 154 is provided between a sleeve 125 slidably fitted with the reaction force piston 92 and the reaction piston 92 so that brake liquid flows from the through hole 144 to the release chamber 135 in a full opened state when the reaction force piston 92 is not operated under the non operation state, and the flow of the brake liquid from the through hole 144 to the release chamber 135 is restricted when the reaction force piston 92 is operated accompanied by operation of a brake operation member 11. <P>COPYRIGHT: (C)2005,JPO&NCIPI |