PNEUMATIC BOOSTER

摘要

A pneumatic booster capable of suppressing braking force from becoming excessive relative to an input force applied to a brake pedal. A valve mechanism (13) includes a poppet valve (14) movably attached to a small-diameter cylindrical portion of a valve body (6), an annular abutment portion formed on a plunger body of a plunger (20) to bring a variable-pressure chamber B into and out of communication with the atmosphere by unseating from and seating on the poppet valve, respectively, a movable seat member (29) movably guided by the valve body to bring a negative-pressure chamber A and the variable-pressure chamber B into and out of communication with each other, and a transmitting member (31) having one end abutting against the movable seat member and the other end disposed to surround a stepped piston of the plunger so as to be abuttable against a reaction disk (27).

主权项

1. A pneumatic booster comprising:
a power piston dividing an interior of a housing into a constant-pressure chamber and a variable-pressure chamber; a valve body connected to the power piston, the valve body being movable in the housing; a plunger disposed in the valve body, the plunger being movable in response to an operation of a brake pedal; a valve device introducing atmospheric air into the variable-pressure chamber in response to movement of the plunger to produce a differential pressure between the constant-pressure chamber and the variable-pressure chamber; and an output rod transmitting thrust of the valve body to a master cylinder through a reaction member when the power piston is activated to move together with the valve body in accordance with the differential pressure; wherein a part of reaction force acting on the output rod is transmitted to the brake pedal through the plunger having a distal end abutting against the reaction member, and wherein introduction of atmospheric air into the variable-pressure chamber by the valve device is stopped by advance of the valve body; the valve device comprising: a poppet valve movably attached to the valve body; a first seat part formed on the plunger to bring the variable-pressure chamber and atmosphere into and out of communication with each other by unseating from and seating on the poppet valve, respectively; a second seat part movably guided by the valve body to bring the variable-pressure chamber and the constant-pressure chamber into and out of communication with each other by unseating from and seating on the poppet valve, respectively; and a transmitting member having a proximal end abutting against the second seat part and a distal end disposed adjacent to the distal end of the plunger so as to be abuttable against the reaction member; wherein the transmitting member transmits a part of reaction force from the reaction member to the poppet valve through the second seat part to move the poppet valve, thereby unseating the first seat part and the poppet valve from each other, and thus allowing the variable-pressure chamber to communicate with the atmosphere.