초록 ▼

A vacuum servo unit includes a partition member having an outer periphery that engages the movable wall member in an air tight manner. A receiving chamber is defined between the partition member and the movable wall member, and the receiving chamber is adapted to be communicated with the atmosphere.

A vacuum servo unit includes a partition member having an outer periphery that engages the movable wall member in an air tight manner. A receiving chamber is defined between the partition member and the movable wall member, and the receiving chamber is adapted to be communicated with the atmosphere. A passage that introduces atmospheric air into the receiving chamber is engaged in an air tight manner with the partition member and extends through the constant pressure chamber. A change member in the form of a solenoid valve selectively communicates the receiving chamber with the constant pressure chamber or with the atmosphere. Accordingly, the servo efficiency of the vacuum servo unit is increased. In addition, the unit can be operated automatically by supplying electric power to thereby increase brake force so that the brake feeling is advanced.

대표청구항 ▼

[ What is claimed is:] [1.] A vacuum servo unit for a vehicle braking system comprising:a housing in which is defined a pressure chamber;a movable wall member positioned in said housing for dividing said pressure chamber into a front chamber for communicating with a negative pressure source and a re

[ What is claimed is:] [1.] A vacuum servo unit for a vehicle braking system comprising:a housing in which is defined a pressure chamber;a movable wall member positioned in said housing for dividing said pressure chamber into a front chamber for communicating with a negative pressure source and a rear chamber for selectively communicating with the atmosphere and with the negative pressure source for being moved in forward and backward directions;a movable power piston connected with said movable wall member;an input member positioned in said movable power piston that is movable in forward and backward directions in response to brake actuation;an output member outputting a propulsion on said movable power piston in response to movement of said movable wall member;a control member for selectively communicating said rear chamber with said negative pressure source or the atmosphere according to movement of said input member against said movable power piston;a supplementary movable wall member provided in said front chamber for moving in forward and backward directions and adapted to engage said output member;a seal member provided between said supplementary movable wall member and said movable wall member, said seal member having an outer peripheral portion in air tight engagement with an outer peripheral portion of said supplementary movable wall member to form a supplementary variable pressure chamber between at least a rear face of said supplementary movable wall member and a front face of said seal member, said supplementary variable pressure chamber being divided in an air-tight manner from said front chamber; anda change member for selectively communicating said supplementary variable pressure chamber with the negative pressure source or with the atmosphere.