| 摘要 |
PROBLEM TO BE SOLVED: To provide a simply structured and compact negative pressure type booster capable of responding to a manipulated variable of a brake operation member. SOLUTION: A negative pressure type booster 1 has a movable wall 3 for separating the internal space of a housing 2 into a constant pressure chamber 4 always communicating with a negative pressure source, and a pressure changing chamber 5 isolated from the constant pressure chamber 4 airtightly, as well as a power piston 6 for outputting a brake force to an output member via an axial travel. In addition, the booster 1 has an auxiliary movable wall 17 laid within the constant pressure chamber 4 in such a state as capable of engagement with the output member 11, a seal member 18 airtightly engaged with the auxiliary movable wall 17 for forming an auxiliary pressure changing chamber 19 therewith, and a solenoid valve 23 for communicating the auxiliary pressure changing chamber 19 to the constant pressure chamber 4 or the atmosphere selectively. |
