| 摘要 |
PROBLEM TO BE SOLVED: To provide a barometric pressure type booster which includes a pneumatic control valve device for anti-skid control and also includes a fail-safe mechanism against possible mechanical damage to a spring. SOLUTION: A fail-safe mechanism 80 comprises a magnet 84 which exerts a force Fp on the valve member of a second valve device 70 for pneumatic control in the same direction as a spring 74 and an electromagnetic acting part for fail-safe which exerts a force (f) on the valve member in the time of anti-skid control-in one same direction as the exciting force Fc of an acting solenoid 76. Also the electromagnetic acting part includes a solenoid 86 and a plunger 88 and, depending on whether or not the force (f) is applied based on the excitation of the solenoid 86, the second valve device 70 is locked to a normal position in the time of non-antiskid control or unlocked in the time of antiskid control. In addition, for the second valve device, either a 4-port 2-position type or 3-port 2-position type solenoid valves can be used. From the view point of simplifying a valve structure, the latter 3-port 2-position type is more desirable. |
