Pneumatic booster and brake system

Patent metadata

Field	Value
Publication number	US-9656647-B2
Application number	US-201314388432-A
Country	US
Kind code	B2
Filing date	Mar 26, 2013
Priority date	Jul 6, 2012
Publication date	May 23, 2017
Grant date	May 23, 2017

Abstract

A pneumatic booster ( 40 ) disposed between a brake pedal ( 5 ) and a master cylinder ( 7 ) includes a cylindrical member ( 60 ) provided on an outer circumferential side of an output rod ( 58 ). A seal member ( 62 ) seals between an outer circumferential side of the cylindrical member and a cylindrical portion of a front shell, and an O-ring seals between the cylindrical member and the output rod. The cylindrical member causes a differential pressure between a negative pressure chamber (A) and an atmosphere chamber (C) to be applied to a valve body ( 46 ). One axial side of the cylindrical member is configured to cause an atmosphere pressure to be applied to the valve body by abutting against a cylindrical protruding portion of the valve body, thereby pushing the valve body with the aid of the differential pressure in the direction as a biasing direction of a return spring.

First claim

The invention claimed is:

1. A pneumatic booster comprising:
a valve body coupled to a power piston dividing an inside of a housing into a constant pressure chamber and a variable pressure chamber, and sealed from an atmosphere on a variable pressure chamber side in the housing;
a biasing member disposed in the housing and configured to bias the valve body toward the variable pressure chamber side; and
an output rod configured to output an axial displacement of the valve body out of the housing
wherein the valve body includes a portion configured to receive a differential pressure between the constant pressure chamber and the atmosphere, on a constant pressure chamber side in the housing,
wherein the portion includes a cylindrical member disposed on an outer circumferential side of the output rod and sealed on an outer circumferential side thereof between the cylindrical member and the housing to cause an atmospheric pressure to be applied to the valve body,
wherein a seal on the valve body from the atmosphere on the variable pressure chamber side in the housing is realized by a seal member fixed to the housing and disposed in such a manner that an outer circumferential surface of the valve body slidably moves on the seal member, and
wherein the cylindrical member causes the atmospheric pressure to be applied by abutting against the valve body.

2. The pneumatic booster according to claim 1 , wherein the cylindrical member causes the atmospheric pressure to be applied to the valve body by abutting against the output rod while being sealed on an inner circumferential side thereof between the cylindrical member and the output rod.

3. The pneumatic booster according to claim 1 , wherein an outer diameter dimension of the cylindrical member is generally equal to an outer diameter dimension of a portion of the valve body that is located on the variable pressure chamber side in the housing.

4. The pneumatic booster according to claim 1 , wherein an outer diameter dimension of the cylindrical member is equal to or larger than an outer diameter dimension of a portion of the valve body that is located on the variable pressure chamber side in the housing.

5. The pneumatic booster according to claim 1 , wherein a reaction disk is provided between the output rod and the valve body.

6. A pneumatic booster comprising:
a housing:
a power piston dividing an inside of the housing into a constant pressure chamber and a variable pressure chamber;
a valve body coupled to the power piston and sealed from an atmosphere on a variable pressure chamber side in the housing;
a plunger movably disposed in the valve body;
an input rod coupled to the plunger;
an output rod coupled to the valve body;
a biasing member configured to bias the valve body toward an input rod side;
a vacuum passage configured to establish communication between the constant pressure chamber and the variable pressure chamber; and
an atmosphere passage configured to open the variable pressure chamber to the atmosphere,
wherein a movement of the plunger relative to the valve body closes the vacuum passage to block the communication between the constant pressure chamber and the variable pressure chamber, and opens the atmosphere passage to introduce the atmosphere into the variable pressure chamber, whereby the power piston is thrust with the aid of a differential pressure generated between the constant pressure chamber and the variable pressure chamber,
wherein a cylindrical member connected to the valve body and sealed from the atmosphere on a constant pressure chamber side in the housing is disposed on an outer circumference of the output rod,
wherein a seal on the valve body from the atmosphere on the variable pressure chamber side in the housing is realized by a seal member fixed to the housing and disposed in such a manner that an outer circumferential surface of the valve body slidably moves on the seal member, and
wherein the cylindrical member causes the atmospheric pressure to be applied by abutting against the valve body.

7. The pneumatic booster according to claim 6 , wherein the cylindrical member causes the atmospheric pressure to be applied to the valve body by abutting against the output rod while being sealed on an inner circumferential side thereof between the cylindrical member and the output rod.

8. The pneumatic booster according to claim 6 , wherein an outer diameter dimension of the cylindrical member is generally equal to an outer diameter dimension of a portion of the valve body that is located on the variable pressure chamber side in the housing.

9. The pneumatic booster according to claim 6 , wherein an outer diameter dimension of the cylindrical member is equal to or larger than an outer diameter dimension of a portion of the valve body that is located on the variable pressure chamber side in the housing.

10. The pneumatic booster according to claim 6 , wherein a reaction disk is provided between the output rod and the valve body.

11. A brake system comprising:
a master cylinder configured to supply a hydraulic pressure to a wheel cylinder mounted on a wheel of a vehicle;
a pneumatic booster configured to thrust a piston disposed in the master cylinder according to an operation performed on a brake pedal; and
a hydraulic supply apparatus disposed between the master cylinder and the wheel cylinder and capable of supplying brake fluid in the master cylinder to the wheel cylinder, the hydraulic supply apparatus being configured to supply the brake fluid in the master cylinder to the wheel cylinder according to a pressure state in a constant pressure chamber to thereby adjust a hydraulic pressure in the wheel cylinder in such a manner that this hydraulic pressure reaches or exceeds a hydraulic pressure that the pneumatic booster can generate in the master cylinder,
wherein the pneumatic booster includes:
a valve body coupled to a power piston dividing an inside of a housing into the constant pressure chamber and a variable pressure chamber, and sealed from an atmosphere on a variable pressure chamber side in the housing;
a biasing member disposed in the housing and configured to bias the valve body toward the variable pressure chamber side; and
an output rod configured to output an axial displacement of the valve body out of the housing,

wherein the valve body is configured to receive a differential pressure between the constant pressure chamber and the atmosphere on a constant pressure chamber side in the housing due to a cylindrical member disposed on an outer circumferential side of the output rod and sealed on an outer circumferential side thereof between the cylindrical member and the housing to cause an atmospheric pressure to be applied to the valve body,
wherein a seal on the valve body from the atmosphere on the variable pressure chamber side in the housing is realized by a seal member fixed to the housing and disposed in such a manner that an outer circumferential surface of the valve body slidably moves on the seal member, and
wherein the cylindrical member causes the atmospheric pressure to be applied by abutting against the valve body.

12. The pneumatic booster according to claim 11 , wherein the cylindrical member causes the atmospheric pressure to be applied to the valve body by abutting against the output rod while being sealed on an inner circumferential side thereof between the cylindrical member and the output rod.

13. The pneumatic booster according to claim 11 , wherein an outer diameter dimension of the cylindrical member is generally equal to an outer diameter dimension of a portion of the valve body that is located on the variable pressur

Assignees

• Hitachi Automotive Systems Ltd

Inventors

• Endo Mitsuhiro
• Watanabe Shuzo

Classifications

• B60T13/241 Primary

  Differential pressure systems · CPC title

• B60T13/57

  characterised by constructional features of control valves · CPC title

• B60T13/52 Primary

  indirect, i.e. vacuum booster units · CPC title

• F15B13/021

  Valves for interconnecting the fluid chambers of an actuator · CPC title