US3918768A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic braking systems
Assignee: Girling Ltd
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Filing: 1974-06-17
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Granted: 1975-11-11
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Expires: 1994-06-17
Abstract
Abstract A vehicle hydraulic braking system incorporates a power valve assembly and means for relieving pressure in the event of a skid. A piston is advanced on application of the brake pedal to open a first valve controlling a connection to a fluid pressure source and to close a second valve controlling a connection to a reservoir. The piston can be retracted by supply of pressure fluid to the assembly in the event of a skid.
Inventors
- 👤 Glyn Phillip Reginald Farr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 11:15
CPC Classifications
B; B60; B60T; B60T13/00; B60T13/10; B60T13/12; B60T13/14; B60T8/00; B60T8/18; B60T8/1812; B60T8/1831; B60T8/32; B60T8/34; B60T8/44; B60T8/445
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
259 words
A vehicle hydraulic braking system of the kind incorporating a power valve assembly for applying the brakes and means for relieving the braking pressure in the event of a skid condition, wherein said power valve assembly comprises a cylinder, a piston working in said cylinder and responsive to actuation of a brake pedal, a normally-closed first valve comprising a first valve member controlling fluid communication through a first valve seat of which opposite sides respectively communicate with a connection to a first fluid pressure source and with a connection to a brake actuator, a normally-open second valve comprising a second valve member controlling fluid communication through a second valve seat of which opposite sides respectively communicate with a connection to a reservoir and with a connection to said brake actuator, said piston cooperating with said valve members so that upon axial movement of said piston in response to actuation of said brake pedal said first valve is opened and said second valve is closed, said piston and said cylinder defining between them a pressure space so arranged that on pressurisation of said pressure space said piston is retracted to close said first valve and open second valve to relieve the braking pressure, and wherein said means for relieving the braking pressure comprises a second fluid pressure source, a fluid connection between said second fluid pressure source and said pressure space of said power valve assembly, and a normallyclosed valve means incorporated in said fluid connection and responsive to a skid condition to supply said pressure space with pressure fluid.
Claim 2
Dependent Claim
259 words
A vehicle hydraulic braking system of the kind incorporating a power valve assembly for applying the brakes and means for relieving the braking pressure in the event of a skid condition, wherein said power valve assembly comprises a cylinder, a piston working in said cylinder and responsive to actuation of a brake pedal, a normally-closed first valve comprising a first valve member controlling fluid communication through a first valve seat of which opposite sides respectively communicate with a connection to a first fluid pressure source and with a connection to a brake actuator, a normally-open second valve comprising a second valve member controlling fluid communication through a second valve seat of which opposite sides respectively communicate with a connection to a reservoir and with a connection to said brake actuator, said piston cooperating with said valve members so that upon axial movement of said piston in response to actuation of said brake pedal said first valve is opened and said second valve is closed, said piston and said cylinder defining between them a pressure space so arranged that on pressurisation of said pressure space said piston is retracted to close said first valve and open second valve to relieve the braking pressure, and wherein said means for relieving the braking pressure comprises a second fluid pressure source, a fluid connection between said second fluid pressure source and said pressure space of said power valve assembly, and a normallyclosed valve means incorporated in said fluid connection and responsive to a skid condition to supply said pressure space with pressure fluid.
Claim 3
Dependent Claim
30 words
An hydraulic braking system as claimed in clain 1 in which said connections to said brake actuator comprise a common fluid line leading directly to a brake incorporating said actuator.
Claim 4
Dependent Claim
22 words
An hydraulic braking system as claimed in claim 1 in which said first and second fluid pressure sources comprise a single source.
Claim 5
Dependent Claim
42 words
An hydraulic braking system as claimed in claim 1 in which the normally-closed valve means in the fluid connection from said second pressure source to said pressure space comprises an electrically operated control valve actuated in response to an electrical skid signal.
Claim 6
Dependent Claim
35 words
An hydraulic braking system as claimed in claim 1 in which the cylinder and piston are stepped and said pressure space is defined between the step in the piston and the step in the bore.
Claim 7
Dependent Claim
39 words
An hydraulic braking system as claimed in claim 1 in which the piston is formed with the valve seat for one of the valves and with a passage terminating in that seat and controlled by the corresponding valve member.
Claim 8
Dependent Claim
45 words
An hydraulic braking system as claimed in claim 1 in which a second pressure space is defined between the piston and the cylinder and the arrangement is such that on actuation of the brake pedal the second pressure space is pressurised to advance the piston.
Claim 9
Dependent Claim
79 words
An hydraulic braking system as claimed in claim 7 in which the first valve seat communicates with the brake actuator through a normally open third valve of the power valve assembly, and a normally closed fourth valve of the power valve assembly is arranged to control a connection between said second Pressure space and the outlet of said third valve, the third valve being adapted to close and the fourth valve to open on failure of the pressure source.
Claim 10
Dependent Claim
45 words
An hydraulic braking system as claimed in claim 4 incorporating at least two brake circuits in which each brake circuit is controlled by a respective power valve assembly, respective control valves being provided for supplying pressure fluid to retract the respective piston of each assembly.
Claim 11
Dependent Claim
79 words
An hydraulic braking system as claimed in claim 9 in which there are two brake circuits and each circuit is connected to a respective pair of actuators of a pair of front wheel brakes on opposite sides of the vehicle and to an actuator of a respective rear wheel brake, each rear wheel being provided with a skid sensing means adapted to send a skid signal to the control valve of the brake circuit associated with that rear wheel.
Claim 12
Dependent Claim
136 words
A power valve assembly for an hydraulic braking system of the kind set forth comprising a housing defining a stepped bore, a stepped piston working in said bore, a first inlet connection for connection to a fluid pressure source, a first valve controlling fluid flow through the first inlet, an outlet for connection to a reservoir, a second valve controlling fluid flow through the outlet, and a second inlet leading into a chamber formed between the step in the housing and the step in the piston and adapted for connection to a control valve controlling fluid under pressure, the arrangement being such that movement of the piston in the forward direction closes the second valve and opens the first valve and pressure fluid admitted to said chamber tends to move the piston in the opposite direction.
Claim 13
Dependent Claim
136 words
A power valve assembly for an hydraulic braking system of the kind set forth comprising a housing defining a stepped bore, a stepped piston working in said bore, a first inlet connection for connection to a fluid pressure source, a first valve controlling fluid flow through the first inlet, an outlet for connection to a reservoir, a second valve controlling fluid flow through the outlet, and a second inlet leading into a chamber formed between the step in the housing and the step in the piston and adapted for connection to a control valve controlling fluid under pressure, the arrangement being such that movement of the piston in the forward direction closes the second valve and opens the first valve and pressure fluid admitted to said chamber tends to move the piston in the opposite direction.
Claim 14
Dependent Claim
68 words
A power valve assembly as claimed in claim 11 incorporating a normally open third valve controlling the outlet from said first valve, and a normally closed fourth valve connected between the outlet of said third valve and a pressure space behind the larger diameter portion of the stepped piston, the third valve being adapted to close and the fourth valve to open on failure of the pressure source.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-11-10 | 1979-05-12 | 1979-11-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-10 | 1983-05-12 | 1983-11-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-10 | 1987-05-12 | 1987-11-11 | $7700.00 | Window Closed / Lapsed |