VACCUM SERVO DEVICE FOR VEHICLE BRAKE

摘要

PURPOSE: To permit traction control independently from normal brake control by providing a solenoid valve in a housing partitioned into a vacuum pressure chamber and an atmospheric pressure chamber by a diaphragm inside it and controlling a pressure in the vacuum pressure chamber by this solenoid valve. CONSTITUTION: This vacuum servo unit for brake device of vehicle is provided with an actuator rod assembly 11 in a housing 1 partitioned into a vacuum pressure chamber 3 and an atmospheric pressure chamber 5 by a diaphragm 7 inside it. This assembly 11 has a valve assembly 17 provided with a valve control piston 23, which is provided with a key 21 limiting a motion of the piston 23 and engageable with a fixed stopper of the housing 1. In this case, a solenoid valve 25 is provided on a wall of the housing 1. This unit controls in such a way that a passage member 29 having the flexibility in the axial direction and a passage 26 between vacuum pressure chamber 3 and it are opened at the time of normal braking and that the communication between the passage 26 and the vacuum pressure chamber 3 is shut off to open the passage 26 to the atmospheric air at the time of traction control.