Patent US4976501A successfully refreshed from Google Patents.
US4976501A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fluid accumulator for use in a vehicle anti-lock brake system
Assignee: ZF Active Safety US Inc
•
Filing: 1989-07-31
•
Granted: 1990-12-11
•
Expires: 2009-07-31
Abstract
Abstract An accumulator assembly for a vehicle anti-lock brake system receives and temporarily stores fluid during pressure reduction phases of the anti-lock operation, and maintains fluid stored therein substantially at or near zero pressure during anti-lock operation. The accumulator enables the fluid pressure to the controlled brakes to be reduced to substantially near zero pressure. The accumulator is further operative, after braking of the vehicle, to apply a predetermined pressure above zero pressure to the brake fluid stored therein to enable the fluid to be returned to the brake system. The accumulator is advantageously used in a pumpless anti-lock system which is operative to control the rear disc brakes of a light pick-up truck.
Inventors
- 👤 Gerald M. Sivulka
- 👤 Peter Every
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 14:41
CPC Classifications
B; B60; B60T; B60T13/00; B60T13/10; B60T13/12; B60T13/14; B60T8/00; B60T8/17; B60T8/176; B60T8/1761; B60T8/17616; B60T11/00; B60T11/10; B60T11/28; B60T11/34; B60T8/1763; B60T8/17636; B60T8/32; B60T8/34; B60T8/341; B60T8/343; B60T8/344; B60T8/36; B60T8/3615; B60T8/363; B60T8/3635; B60T8/3675; B60T8/40; B60T8/404; B60T8/4054; B60T8/42; B60T8/4275; B60T8/4291; B60T8/50; B60T8/5018; B60T8/5025; B60T8/58; Y; Y10; Y10S; Y10S303/00; Y10S303/02; Y10S303/03; Y10S303/04; Y10S303/11
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
167 words
In a vehicle anti-lock brake system adapted to control the fluid pressure in a brake circuit to at least one selected wheel brake to correct an impending lock-up condition of an associated wheel, the brake system including a valve means connected between the selected wheel brake and a fluid accumulator, the valve means being selectively controlled during anti-lock operation of the brake system to supply brake fluid to the fluid accumulator for reducing fluid pressure to the selected wheel brake, the fluid accumulator comprising: a reservoir having an opening for receiving and retaining brake fluid during anti-lock operation; means for maintaining fluid pressure of said brake fluid within said reservoir at a first predetermined pressure during anti-lock operation; and means operative only when the brake system is not under anti-lock operation for applying a second predetermined pressure greater than said first predetermined pressure to said brake fluid within said reservoir to enable said brake fluid to flow through said opening and be returned to the brake circuit.
Claim 2
Dependent Claim
167 words
In a vehicle anti-lock brake system adapted to control the fluid pressure in a brake circuit to at least one selected wheel brake to correct an impending lock-up condition of an associated wheel, the brake system including a valve means connected between the selected wheel brake and a fluid accumulator, the valve means being selectively controlled during anti-lock operation of the brake system to supply brake fluid to the fluid accumulator for reducing fluid pressure to the selected wheel brake, the fluid accumulator comprising: a reservoir having an opening for receiving and retaining brake fluid during anti-lock operation; means for maintaining fluid pressure of said brake fluid within said reservoir at a first predetermined pressure during anti-lock operation; and means operative only when the brake system is not under anti-lock operation for applying a second predetermined pressure greater than said first predetermined pressure to said brake fluid within said reservoir to enable said brake fluid to flow through said opening and be returned to the brake circuit.
Claim 3
Dependent Claim
17 words
The anti-lock brake system according to claim 1 wherein said first predetermined pressure is substantially zero pressure.
Claim 4
Dependent Claim
100 words
The anti-lock brake system according to claim 1 wherein the valve means includes a normally open isolation valve connected between a vehicle master cylinder and the selected wheel brake, and a normally closed dump valve connected between the selected wheel brake and said reservoir, and a control means operable to detect an impending lock-up condition of an associated wheel and to operate said isolation valve and said dump valve to correct the impending lock-up condition, the dump valve being selectively opened during anti-lock operation to supply brake fluid to said reservoir for reducing fluid pressure to the selected wheel brake.
Claim 5
Dependent Claim
29 words
The anti-lock brake system according to claim 1 wherein said means for maintaining is operative to maintain said first predetermined pressure only during anti-lock operation of the brake system.
Claim 6
Dependent Claim
25 words
The anti-lock brake system according to claim 1 wherein said means for applying applies said second predetermined pressure after anti-lock operation of the brake system.
Claim 7
Dependent Claim
120 words
An accumulator assembly for use in a vehicle anti-lock brake system comprising: a housing defining a cavity; a piston slidably mounted within said cavity and cooperating with said cavity for defining a reservoir for receiving and temporarily storing brake fluid during operation of the anti-lock brake system; spring means coupled to said piston for biasing said piston in a direction which exerts a predetermined force on said piston to maintain fluid stored in said reservoir at a predetermined pressure; and means connected to said spring means and operative to reduce said force exerted on said piston to reduce the pressure of the fluid stored in said reservoir during at least a portion of the operation of the anti-lock brake system.
Claim 8
Dependent Claim
120 words
An accumulator assembly for use in a vehicle anti-lock brake system comprising: a housing defining a cavity; a piston slidably mounted within said cavity and cooperating with said cavity for defining a reservoir for receiving and temporarily storing brake fluid during operation of the anti-lock brake system; spring means coupled to said piston for biasing said piston in a direction which exerts a predetermined force on said piston to maintain fluid stored in said reservoir at a predetermined pressure; and means connected to said spring means and operative to reduce said force exerted on said piston to reduce the pressure of the fluid stored in said reservoir during at least a portion of the operation of the anti-lock brake system.
Claim 9
Dependent Claim
23 words
The anti-lock brake system according to claim 6 wherein said means connected to said spring means reduces the pressure to substantially zero pressure.
Claim 10
Dependent Claim
100 words
The brake system according to claim 6 wherein the vehicle anti-lock brake system includes a normally open isolation valve connected between a vehicle master cylinder and the selected wheel brake, and a normally closed dump valve connected between the selected wheel brake and said reservoir, and a control means operable to detect an impending lock-up condition of an associated wheel and to operate said isolation valve and said dump valve to correct the impending lock-up condition, said dump valve being selectively opened during anti-lock operation to supply brake fluid to said reservoir for reducing pressure to the selected wheel brake.
Claim 11
Dependent Claim
23 words
The anti-lock brake system according to claim 6 wherein said spring means exerts said predetermined force after anti-lock operation of the brake system.
Claim 12
Dependent Claim
114 words
An accumulator assembly for use in a vehicle anti-lock brake system comprising; a housing defining a cavity; a piston slidably mounted within said cavity and cooperating with said cavity for defining a reservoir for receiving and temporarily storing brake fluid during operation of the anti-lock system; spring means coupled to said piston for biasing said piston in a direction which exerts a predetermined force on said piston to maintain fluid stored in said reservoir at a predetermined pressure; plunger means connected to said spring means and operative to compress said spring means such that said spring means exerts no force on said piston; and means for moving said plunger to compress said spring means.
Claim 13
Dependent Claim
114 words
An accumulator assembly for use in a vehicle anti-lock brake system comprising; a housing defining a cavity; a piston slidably mounted within said cavity and cooperating with said cavity for defining a reservoir for receiving and temporarily storing brake fluid during operation of the anti-lock system; spring means coupled to said piston for biasing said piston in a direction which exerts a predetermined force on said piston to maintain fluid stored in said reservoir at a predetermined pressure; plunger means connected to said spring means and operative to compress said spring means such that said spring means exerts no force on said piston; and means for moving said plunger to compress said spring means.
Claim 14
Dependent Claim
106 words
The accumulator assembly according to claim 10 wherein the vehicle anti-lock brake system includes a normally open isolation valve connected between a vehicle master cylinder and a selected wheel brake, and a normally closed dump valve connected between the selected wheel brake and said reservoir, and a control means operable to detect an impending lock-up condition of an associated wheel and to operate said isolation valve and said dump valve to control the fluid pressure to correct the impending lock-up condition, said dump valve being selectively opened during anti-lock operation to supply brake fluid to said reservoir for reducing fluid pressure to the selected wheel brake.
Claim 15
Dependent Claim
45 words
The accumulator assembly according to claim 11 wherein said plunger means is shiftable between an unactuated position wherein said spring means exerts said predetermined force on said piston and an actuated position wherein said spring means is compressed to exert no force on said piston.
Claim 16
Dependent Claim
18 words
The accumulator assembly according to claim 12 wherein said plunger means is hydraulically shifted to said actuated position.
Claim 17
Dependent Claim
19 words
The accumulator assembly according to claim 13 wherein said plunger means is shifted by means of pressurized brake fluid.
Claim 18
Dependent Claim
34 words
The accumulator assembly according to claim 14 wherein said housing includes a passageway for supplying brake fluid to shift said plunger means, said passageway including a restriction for limiting fluid flow through said passageway.
Claim 19
Dependent Claim
21 words
The accumulator assembly according to claim 13 wherein said plunger means is shifted to said unactuated position by said spring means.
Claim 20
Dependent Claim
21 words
The accumulator assembly according to claim 12 wherein said plunger means is shifted to said actuated position only during anti-lock operation.
Claim 21
Dependent Claim
30 words
The accumulator assembly according to claim 17 wherein said plunger means is shifted to said actuated position after said dump valve has been opened to supply fluid to said reservoir.
References Cited (Backward Citations)
US3521934A
Cited
US3414336A
Cited
US3532391A
Cited
US3574416A
Cited
US3524684A
Cited
US3645584A
Cited
US3639009A
Cited
US3677608A
Cited
US3690736A
Cited
US3756666A
Cited
US3715145A
Cited
US4453782A
Cited
US4418966A
Cited
US4480877A
Cited
US4509802A
Cited
US4597611A
Cited
US4799048A
Cited
US4673226A
Cited
US4790607A
Cited
US4668023A
Cited
US4828335A
Cited
US4865399A
Cited
US4765691A
Cited
US4844558A
Cited
US4779936A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-12-10 | 1994-06-11 | 1994-12-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-12-10 | 1998-06-11 | 1998-12-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-12-10 | 2002-06-11 | 2002-12-11 | $7700.00 | Window Closed / Lapsed |