| 摘要 |
PROBLEM TO BE SOLVED: To suitably perform smooth control on an effective condition of the brake boosting action by gradually changing assist force. SOLUTION: A variable pressure chamber 13 and a negative pressure chamber 15 are arranged in a brake booster 1, and a first ventilation control valve 21 and an orifice 23 or the like are arranged to adjust pressure of both chambers 13 and 15. Among these, the first ventilation control valve 21 is a solenoid valve arranged in an atmosphere introducing first ventilating passage 25 connected to the variable pressure chamber 13, and is controlled so as to be driven in opening or closing two positions, for example, at antiskid control time. The orifice 23 is arranged in a second ventilating passage 25 branching off from the first ventilating passage 25, and the atmosphere can be gradually introduced to the variable pressure chamber 13 side through the orifice 23. |
