| 摘要 |
PURPOSE: To more rapidly assist an emergency brake by a brake booster by controlling a valve passage by an additional valve to open when an operating member moves more than a movement required for raising a valve body from a second valve body. CONSTITUTION: When a brake pedal is operated more abruptly, a transmitting element 82 abuts on the front surface end of a sleeve 86 to constrain a sleeve 72 forward. Thus, a rear end 78 is raised from a valve seat 76, so that not only atmospheric air flows to a rear chamber 26 from the radially inner area of a filter 48 through an inner space 46 and an intermediate space 44, but also additional air flows to the chamber 26 through a ventilating passage 80. Thus, movable walls 16 and 18 are rapidly pushed forward. When the pedal is released, after operating a brake, a valve body 40 is temporarily raised, separated from a valve seat 32 to come into contact with a valve seat 34 under pressure. On the other hand, the rear end 78 comes into contact with a valve seat 66 under pressure. Consequently, the chamber 26 is separated from a circumferential environment and connected to a chamber 24. |
