Fluid pressure boosting device and brake system employing the same

• US 6,467,267 B2
• Filed: 06/15/2001
• Issued: 10/22/2002
• Est. Priority Date: 07/14/1999
• Status: Expired due to Term

• Current Assignee: DENSO Corporation, Oracle Corporation, Bosch Corporation (Robert Bosch GmbH)
• Original Assignee: DENSO Corporation, Bosch Braking Systems Co Ltd (Robert Bosch GmbH)
• Inventors: Kanazawa, Osamu, Ohsaki, Hiroshi, Yamaga, Hiroyuki, Kakuda, Mitsuru, Sawada, Mamoru, Niino, Hiroaki, Maki, Kazuya, Kobayashi, Michio, Oka, Hiroyuki, Takasaki, Yoshiyasu
• Primary Examiner(s): Look, Edward K.
• Assistant Examiner(s): LESLIE, MICHAEL S
• Application Number:
  US09/881,201
• Publication Number:
  US 20020023437A1
• Time in Patent Office: 494 Days
• Field of Search: 605/52, 605/471, 913/72, 913/73, 913/70, 303/138
• US Class Current: 60/552
• CPC Class Codes: B60T 11/20 Tandem, side-by-side, or other multiple master cylinder units
• CPC Class Codes: B60T 13/161 Systems with master cylinder

Abstract

In a brake fluid pressure boosting device 1 of the present invention, by operation, an input shaft 4 is moves forward to rotate a lever 27 to actuate a control valve 8 so that the control valve 8 produce working fluid pressure corresponding to the input. The working fluid pressure is introduced into the power chamber 6. By this working fluid pressure, the primary piston 37 is actuated to develop master cylinder pressure. On the other hand, the fluid pressure of the power chamber 6 is introduced into the first annular groove 25 of the valve spool 10. By the difference between pressure receiving areas of the first annular groove 25, the valve spool 10 is subjected to rightward force. The position of the pivot of the lever 27 is fixed and the valve spool 10 is controlled in such a manner that the force applied to the valve spool 10 and the spring force of the spool return spring 32 balances with the input, thereby exhibiting the function as a stroke simulator. Because of this function as a stroke simulator, the stroke characteristic on the input side can be changed without affecting the output side.

Claims

1. A fluid pressure boosting device comprising:

a housing,

an input member which is slidably moved in the housing by input applied at a time of an operation,

a control valve which is provided in the housing and operated by the input member for controlling fluid pressure of a fluid pressure source according to a travel of said input member to develop working fluid pressure for operating a working unit so that said working fluid pressure acts on a surface of said control valve in an inoperative direction, and

an elastic member disposed between said control valve and said input member for developing a force according to the travel of the input member relative to the housing so that the force by the elastic member acts on said control valve in an operative direction, said control valve being controlled according to said travel such that a force generated by said working fluid pressure balances with the force generated by said elastic member.

2. A fluid pressure boosting device as claimed in claim 1, wherein in case of a fluid pressure source failure, said working unit is operated by the travel of said input member.

3. A fluid pressure boosting device as claimed in claim 1 or 2, wherein said control valve is composed of a spool valve, said spool valve has a valve spool of which operation is controlled by the force of said elastic member acting in the operative direction and by said working fluid pressure acting in the inoperative direction, and the operation of said valve spool is controlled according to the input of said input member in such a manner that the force by said working fluid pressure acting on the valve spool balances with the force of said elastic member.

4. A fluid pressure boosting device as claimed in claim 3, wherein said spool valve comprises a first throttle valve and a second throttle valve, flow of hydraulic fluid is first throttled by said first throttle valve and then throttled by said second throttle valve to be throttled at two stages.

5. A fluid pressure boosting device as claimed in claim 1 or 2, wherein during an operation when said fluid pressure source is in a normal state, a position of said control valve is fixed regardless of the travel of said input member, and further comprising fluid pressure control means for controlling said working fluid pressure regardless of the input of said input member.

6. A fluid pressure boosting device as claimed in claim 5, further comprising a power chamber into which the working fluid pressure is introduced to produce an output for actuating said working unit, and a reaction chamber into which said working fluid pressure is introduced to apply reaction force to said input member, wherein

said fluid pressure control means is a pressure control valve for controlling the working fluid pressure of at least one of said power chamber and said reaction chamber.

7. A fluid pressure boosting device as claimed in claim 6, wherein said pressure control valve controls said working fluid pressure or the fluid pressure of said fluid pressure source and supplies it into at least one of said power chamber and said reaction chamber.

8. A fluid pressure boosting device as claimed in claim 5, further comprising a power chamber into which the working fluid pressure is introduced to produce an output for actuating said working unit, and a pressure control chamber into which said working fluid pressure is introduced to control said output, wherein

said fluid pressure control means is a pressure control valve for controlling the working fluid pressure of at least one of said power chamber and said pressure control chamber.

9. A fluid pressure boosting device as claimed in claim 8, wherein said pressure control valve controls said working fluid pressure or the fluid pressure of said fluid pressure source and supplies it into at least one of said power chamber and said pressure control chamber.

10. A fluid pressure boosting device as claimed in claim 5, wherein said fluid pressure control means is an electromagnetic solenoid which generates biasing force biasing said control valve in at least one of the operative direction and the inoperative direction.

11. A fluid pressure boosting device as claimed in claim 5, wherein said control valve comprises a valve spool of which operation is controlled by the force of said elastic member acting in the operative direction and by said working fluid pressure acting in the inoperative direction and a valve sleeve fixed to the housing of said fluid pressure boosting device, and wherein said valve spool is moved relative to said valve sleeve according to the input of said input member in such a manner that force by said working fluid pressure acting on the valve spool balances with the force of said elastic member.

12. A fluid pressure boosting device as claimed in claim 11, wherein said valve spool is formed with an annular groove into which said working fluid pressure is introduced during its operation, wherein a pressure receiving area of a pressure receiving surface of said annular groove which receives said working fluid pressure in the inoperative direction of said valve spool is set larger than a pressure receiving area of a pressure receiving surface of said annular groove which receives said working fluid pressure in the operative direction of said valve spool.

13. A fluid pressure boosting device as claimed in claim 5, further comprising a lever disposed between said elastic member and said control valve, wherein said lever is rotated by the force of said elastic member corresponding to the travel of said input member to act on said control valve in the operative direction, a position of a pivotal point of said lever is fixed regardless of the travel of said input member, and the operation of said control valve is controlled according to the input of said input member in such a manner that the force generated by said working fluid pressure balances with a force generated by rotation of said lever.

14. A fluid pressure boosting device as claimed in claim 1, wherein said elastic member is disposed coaxially with said input member, said control valve is disposed to have a predetermined space relative to said input shaft, and further comprising a lever disposed between said elastic member and said control valve wherein said lever is rotated by operation force of said elastic member to act on said control valve in the operative direction, a position of a pivotal point of said lever is fixed regardless of the travel of said input member, and the operation of said control valve is controlled according to the input of said input member in such a manner that the force generated by said working fluid pressure balances with the force generated by the rotation of said lever.

15. A fluid pressure boosting device as claimed in claim 14, wherein said input member is slidable relative to said lever and a slide lubricating member is provided at a sliding portion between said input member and said lever.

16. A fluid pressure boosting device as claimed in claim 15, wherein said slide lubricating member is a bush or a linear bearing.

17. A fluid pressure boosting device as claimed in claim 14, wherein the pivot point of said lever is positioned on an input member side or a control valve side.

18. A fluid pressure boosting device as claimed in claim 1, wherein said elastic member is formed of a plurality of springs or a non-linear spring.

19. A brake system comprising a brake fluid pressure boosting device to intensify an input, a master cylinder which is operated with an output of said brake fluid pressure boosting device to develop master cylinder pressure, and brakes which are operated with braking force generated by the master cylinder pressure, wherein said brake fluid pressure boosting device is the fluid pressure boosting device according to claim 1;

and operation of working fluid pressure control means of the brake fluid pressure boosting device is controlled by a controller and that said controller controls an output of said brake fluid pressure boosting device to obtain a requested increase or decrease in the braking force by controlling the operation of said working fluid pressure control means, wherein said requested increase or decrease in the braking force is requested by one of other controllers other than said controller.

20. A brake system as claimed in claim 19, wherein said working fluid pressure control means has an electromagnetic solenoid for its operation, and said controller for controlling the operation of said working fluid pressure control means supplies electric current to said electromagnetic solenoid wherein said electric current corresponds to an amount of said requested increase or decrease in the braking force requested by said one of the other controllers.

21. A fluid pressure boosting device comprising:

a housing,

an input member which is slidably moved in the housing by input applied at a time of an operation,

a control valve which is provided in the housing and operated by the input member for controlling fluid pressure of a fluid pressure source according to a travel of said input member to develop working fluid pressure for operating a working unit so that said working fluid pressure acts on said control valve in an inoperative direction, and

an elastic member dispersed between said control valve and said input member for developing a force according to a travel of the input member relative to the housing so that the force of the elastic member corresponding to the travel of said input member acts on said control valve in an operative direction, said control valve being controlled according to said travel such that a force generated by said working fluid pressure balances with the force generated by said elastic member, wherein said control valve is a ball valve or cone valve, the force of said elastic member acts on said ball valve or cone valve in the operative direction and said working fluid pressure acts on said ball valve or cone valve in the inoperative direction, and an operation of said ball valve or cone valve is controlled according to the input of said input member in such a manner that the force generated by said working fluid pressure balances with the force generated by said elastic member.