Pneumatic booster

Patent metadata

Field	Value
Publication number	US-10005440-B2
Application number	US-201414554474-A
Country	US
Kind code	B2
Filing date	Nov 26, 2014
Priority date	Nov 29, 2013
Publication date	Jun 26, 2018
Grant date	Jun 26, 2018

Abstract

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 ).

First claim

What is claimed is:

1. A pneumatic booster comprising:
a power piston configured to divide 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 configured to introduce 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 configured to transmit 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,
wherein the transmitting member includes a cylindrical portion having an abutment surface that is abuttable against the reaction member, and a plurality of rod portions extending from the cylindrical portion,
wherein the distal end of the transmitting member forms the abutment surface of the cylindrical portion,
wherein the cylindrical portion is disposed so as to be adjacent to the circumference of the distal end of the plunger and surround the distal end of the plunger,
the proximal end of each of the rod portions forms the proximal end abutting against the second seat part, and
the distal end surface of the distal end of the plunger being abuttable against the reaction member.

2. The pneumatic booster of claim 1 , wherein the valve body has a bore at an inner peripheral side of an abutment surface abutting against the reaction member, the bore having the plunger and the transmitting member disposed therein.

3. A pneumatic booster comprising:
a valve body connected to a power piston dividing an interior of a housing into a constant-pressure chamber and a variable-pressure chamber, 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 configured to introduce 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 configured to transmit 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 movable seat member movably guided by the valve body to selectively unseat from and seat on the poppet valve; and
a transmitting member having a proximal end abutting against the movable seat member 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 controls communication and non-communication between the variable-pressure chamber and atmosphere by selectively unseating from and seating on the poppet valve according to movement of the plunger;
the transmitting member moving the poppet valve with a part of reaction force from the reaction member through the movable seat member, thereby unseating the plunger and the poppet valve from each other, and thus allowing the variable-pressure chamber to communicate with the atmosphere, and
wherein the transmitting member includes a cylindrical portion having an abutment surface that is abuttable against the reaction member, and a plurality of rod portions extending from the cylindrical portion,
wherein the distal end of the transmitting member forms the abutment surface of the cylindrical portion,
wherein the cylindrical portion is disposed so as to be adjacent to the circumference of the distal end of the plunger and surround the distal end of the plunger,
the proximal end of each of the rod portions forms the proximal end abutting against the movable seat member, and
the distal end surface of the distal end of the plunger being abuttable against the reaction member.

4. The pneumatic booster of claim 3 , wherein the valve body has a bore at an inner peripheral side of an abutment surface abutting against the reaction member, the bore having the plunger and the transmitting member disposed therein.

5. A pneumatic booster comprising:
a valve body movable in a housing having a constant-pressure chamber and a variable-pressure chamber defined therein, the valve body having a bore therein;
a plunger disposed in the bore of the valve body, the plunger being movable in response to an operation of a brake pedal;
a valve device configured to introduce atmospheric air into the variable-pressure chamber in response to relative movement between the valve device and the plunger to produce a differential pressure between the constant-pressure chamber and the variable-pressure chamber; and
a reaction member disposed to close the bore of the valve body, the reaction member distributing hydraulic reaction force from a master cylinder between the valve body and the plunger when the valve body is moved by the differential pressure;
the valve device comprising:
a poppet valve movably attached to the valve body; and
a transmitting member having a distal end disposed to be abuttable against the reaction member and a proximal end extending toward the poppet valve so as to be capable of moving the poppet valve,
the transmitting member having a distal end surface disposed so as to face the reaction member at an outer peripheral side of a distal end surface of the plunger in the bore of the valve body,
wherein the distal end surface of the transmitting member is disposed so as to surround the distal end surface of the plunger,
wherein the transmitting member includes a cylindrical portion having an abutment surface that is abuttable against the reaction member, and a plurality of rod portions extending from the cylindrical portion,
wherein the distal end of the transmitting member forms the abutment surface of

Assignees

• Hitachi Automotive Systems Ltd

Inventors

• Watanabe Shuzo

Classifications

• B60T10/00 Primary

  Control or regulation for continuous braking making use of fluid or powdered medium, e.g. for use when descending a long slope · CPC title

• B60T13/57 Primary

  characterised by constructional features of control valves · CPC title

• B60T13/575

  using resilient discs or pads · CPC title