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US3913984A Expired / Lapsed US ⏱️ 0.0 years remaining

Skid control system embodying automatic cycling and fail safe device

Assignee: ZF Active Safety US Inc
•
Filing: 1973-08-24
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Granted: 1975-10-21
•
Expires: 1993-08-24
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Abstract

Abstract Two embodiments of vehicular skid control systems for relieving the brake pressure when an incipient skid condition is sensed. Each system includes a combined check and bleed valve that controls the flow of hydraulic actuating fluid from a master cylinder to the wheel brakes. An expansion chamber is positioned in the fluid circuit between the check and bleed valve and the wheel brakes. An ancillary source of fluid pressure, such as a power steering pump, normally holds the expansion chamber at a minimum volume condition and holds the check and bleed valve open for normal brake operation. When an incipient skid condition is sensed, the expansion chamber is permitted to increase in volume and the combination check and bleed valve is closed. Closure of the check and bleed valve isolates the master cylinder from the wheel brakes and prevents the application of further pressure to the wheel brakes. Expansion of the expansion chamber relieves the existing pressure in the wheel brakes to prevent skidding. A regulator is provided in the circuit connecting the source of ancillary fluid with the expansion chamber for maintaining at least a predetermined pressure in the circuit. The pressure maintained by the regulator is dependent upon the pressure in the brake circuit. Each embodiment includes fail safe device for providing normal brake operation in the event of failure of the source of ancillary fluid. In one embodiment a fail safe device is provided that bypasses the expansion chamber and the check and bleed valve in the event of failure of the ancillary pressure source to provide sufficient pressure. An indicator provides a visual indication to the vehicle operator when the fail safe device is operative so that the source of failure can be investigated and rectified. In the other embodiment a blocking member is provided for retaining the expansion chamber in a minimum volume position and the check and bleed valve in its opened position in the event of failure of the ancillary fluid pressure source. In each embodiment, certain of the elements are spring biased in opposition to the bias exerted by the source of ancillary fluid pressure so that these elements may be automatically cycled each time the vehicle engine is started and stopped.

Inventors

  • 👤 Peter Every
  • 👤 Leonard T Tribe

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-04 23:41
CPC Classifications
B; B60; B60T; B60T8/00; B60T8/32; B60T8/88; B60T8/90

Claims Analysis

Total Claims: 12
Claim 1
Independent Claim 172 words
A skid control system for a self-propelled vehicle having at least one hydraulically operated wheel brake comprising a brake actuating device including a hydraulic circuit for selectively actuating the one wheel brake, skid control means including a valve for controlling the flow through said hydraulic circuit for modifying the actuation of the one wheel brake in response to a predetermined signal to prevent a skid condition, said valve being movable between an opened position and a closed position, a member movable between a normal braking position and a skid control position, said member being operatively connected with said valve and being effective when in its normal braking position for holding said valve in its opened position, said valve being movable to its closed position when said member moves from its normal braking position toward its skid control position but before said member reaches its skid control position, and means for moving said member between said positions in response to the stopping and restarting of the vehicle engine for automatically cycling said member.
Claim 2
Dependent Claim 172 words
A skid control system for a self-propelled vehicle having at least one hydraulically operated wheel brake comprising a brake actuating device including a hydraulic circuit for selectively actuating the one wheel brake, skid control means including a valve for controlling the flow through said hydraulic circuit for modifying the actuation of the one wheel brake in response to a predetermined signal to prevent a skid condition, said valve being movable between an opened position and a closed position, a member movable between a normal braking position and a skid control position, said member being operatively connected with said valve and being effective when in its normal braking position for holding said valve in its opened position, said valve being movable to its closed position when said member moves from its normal braking position toward its skid control position but before said member reaches its skid control position, and means for moving said member between said positions in response to the stopping and restarting of the vehicle engine for automatically cycling said member.
Claim 3
Dependent Claim 65 words
A skid control system as set forth in claim 1 wherein the brake actuating device includes a hydraulic circuit for actuating the one wheel brake and the movable member is operatively connected to a wall of a variable volume chamber, said wall being movable to increase the volume of said chamber under the predetermined signal to relieve the hydraulic pressure on the one wheel brake.
Claim 4
Dependent Claim 40 words
A skid control system as set forth in claim 2 further including fail safe means for delivering actuating fluid to the one wheel brake in tHe event of a failure of said skid control means for providing a brake operation.
Claim 5
Dependent Claim 50 words
A skid control system as set forth in claim 3 wherein the fail safe means includes a bypass circuit and normally closed bypass valve means for controlling the flow through said bypass circuit for delivering fail safe actuating fluid to the one wheel brake independently of the variable volume chamber.
Claim 6
Dependent Claim 29 words
A skid control system as set forth in claim 3 wherein the fail safe means includes blocking means for precluding movement of the wall in the event of failure.
Claim 7
Dependent Claim 52 words
A skid control system as set forth in claim 5 wherein the skid control means further includes a source of ancillary fluid under pressure for operating the means for increasing the volume in the variable volume chamber, said blocking means being responsive to the pressure generated by the source of ancillary fluid.
Claim 8
Dependent Claim 48 words
A skid control system as set forth in claim 6 wherein the ancillary fluid normally holds the means for increasing the volume in the variable volume chamber in a minimum volume condition and the blocking means in a released position in which the wall is free to move.
Claim 9
Dependent Claim 36 words
A skid control system as set forth in claim 1 wherein the last named means includes means driven by the engine for moving the member from one of its positions to the other of its positions.
Claim 10
Dependent Claim 25 words
A skid control system as set forth in claim 8 wherein the means driven by the engine moves the member to its normal braking position.
Claim 11
Dependent Claim 22 words
A skid control system as set forth in claim 8 further including spring means for urging the member to its other position.
Claim 12
Dependent Claim 25 words
A skid control system as set forth in claim 10 wherein the means driven by the engine moves the member to its normal braking position.

References Cited (Backward Citations)

US3515440A Cited
US3602554A Cited
US3610701A Cited
US3747990A Cited
US3672731A Cited
US3813130A Cited
US3810680A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1978-10-20 1979-04-21 1979-10-21 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1982-10-20 1983-04-21 1983-10-21 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1986-10-20 1987-04-21 1987-10-21 $7700.00 Window Closed / Lapsed

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