US3694038A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Actuator assemblies for hydraulic braking systems
Assignee: Girling Ltd
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Filing: 1970-09-17
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Granted: 1972-09-26
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Expires: 1990-09-17
Abstract
Abstract In an actuator assembly for an hydraulic braking system the effective volume of a chamber through which hydraulic fluid under pressure is supplied to a wheel brake is adapted to be varied between a minimum and a maximum value by movement of a piston assembly working in a bore in communication with the chamber. An actuator piston having first and second different faces of different areas normally holds the piston assembly in a position in which the effective volume of the chamber is at a minimum until equal hydraulic pressures are applied to the areas of the actuator piston to cause the actuator piston to retract and permit the piston assembly to be withdrawn whereby the effective volume of the chamber is increased.
Inventors
- 👤 Brian Ingram
- 👤 David Anthony Harries
- 👤 Lancelot Phoenix
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 02:28
CPC Classifications
B; B60; B60T; B60T8/00; B60T8/32; B60T8/34; B60T8/42; B60T8/4208; B60T8/4225; B60T8/4233; B60T13/00; B60T13/10; B60T13/12; B60T13/14; B60T13/141; B60T8/343; B60T8/344; B60T8/345; B60T8/40
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
345 words
An actuator assembly for a vehicle hydraulic braking system comprising a housing, means defining at least one first chamber in said housing having a first inlet for connection to a fluid pressure source and an outlet for connection to a slave cylinder of a wheel brake, a piston assembly working in a first cylinder bore in said housing in communication with said chamber and movable between a first advanced position and a second retracted position, an actuator piston working in a second cylinder bore in said housing and normally acting on said piston assembly to urge said piston assembly into said first advanced position in which the effective volume of said first chamber is at a minimum value and said inlet and outlet connections are open, said actuator piston having a first area at an end of said actuator piston remote from said piston assembly and a second area opposed to said first area, a movable member in said second cylinder bore adjacent said first area of said actuator piston, a compression spring urging said movable member towards said actuator piston, means for applying hydraulic fluid under pressure between said movable member and said first area of said actuator piston to urge said piston assembly into said first advanced position, and a second inlet connection in communication with said second cylinder bore through which hydraulic fluid under pressure is adapted to be admitted into said second bore when the deceleration of a braked wheel controlled by a supply of hydraulic fluid from said outlet exceeds a predetermined value, said supply of hydraulic fluid under pressure admitted to said second bore acting over said second area of said actuator piston to apply to said actuator piston a force to move said actuator piston in a direction away from said piston assembly and permit said piston assembly to be moved towards said second retracted position in which said first inlet connection is closed and the effective volume of said first chamber is increased to reduce pressure in a line between said outlet connection and said slave cylinder.
Claim 2
Dependent Claim
345 words
An actuator assembly for a vehicle hydraulic braking system comprising a housing, means defining at least one first chamber in said housing having a first inlet for connection to a fluid pressure source and an outlet for connection to a slave cylinder of a wheel brake, a piston assembly working in a first cylinder bore in said housing in communication with said chamber and movable between a first advanced position and a second retracted position, an actuator piston working in a second cylinder bore in said housing and normally acting on said piston assembly to urge said piston assembly into said first advanced position in which the effective volume of said first chamber is at a minimum value and said inlet and outlet connections are open, said actuator piston having a first area at an end of said actuator piston remote from said piston assembly and a second area opposed to said first area, a movable member in said second cylinder bore adjacent said first area of said actuator piston, a compression spring urging said movable member towards said actuator piston, means for applying hydraulic fluid under pressure between said movable member and said first area of said actuator piston to urge said piston assembly into said first advanced position, and a second inlet connection in communication with said second cylinder bore through which hydraulic fluid under pressure is adapted to be admitted into said second bore when the deceleration of a braked wheel controlled by a supply of hydraulic fluid from said outlet exceeds a predetermined value, said supply of hydraulic fluid under pressure admitted to said second bore acting over said second area of said actuator piston to apply to said actuator piston a force to move said actuator piston in a direction away from said piston assembly and permit said piston assembly to be moved towards said second retracted position in which said first inlet connection is closed and the effective volume of said first chamber is increased to reduce pressure in a line between said outlet connection and said slave cylinder.
Claim 3
Dependent Claim
35 words
An actuator assembly as claimed in claim 1, incorporating a valve for cutting off communication between said first inlet connection and said chamber upon initial movement of said piston away form said first advanced position.
Claim 4
Dependent Claim
76 words
An actuator assembly as claimed in claim 1, wherein said actuator piston is of differential outline working in a stepped bore and engages at its end of smaller diameter with said piston assembly, said first area being located at the base of a recess in the end of said piston of greater diameter, and said second area being defined by a shoulder at a step in diameter between portions of said stepped piston of different diameters.
Claim 5
Dependent Claim
84 words
An actuator assembly as claimed in claim 3 wherein said shoulder on said actuator piston is spaced from a complementary shoulder at a step at the change in diameter of said stepped bore when said effective volume of the chamber is at said minimum value, and an annular space between the shoulders and surrounding a portion of said actuator piston of lesser diameter defines a second chamber into which hydraulic fluid under pressure is adapted to be admitted though through said second inlet connection.
Claim 6
Dependent Claim
36 words
An actuator assembly as claimed in claim 4, incorporating a metering device for delaying the release of fluid pressure from said second chamber when the supply of hydraulic fluid under pressure to that chamber is terminated.
Claim 7
Dependent Claim
104 words
An actuator assembly as claimed in claim 5, wherein said metering device comprising a cup-shaped piston located in said second chamber and having an axially extending skirt, and a spring for urging said skirt into sealingengagement with said shoulder at said step at the change in diameter in said stepped bore and wherein said cup-shaped piston incorporates in a wall thereof at least one oRifice providing a restricted return path to said second inlet connection for fluid actuator said second chamber after said actuator piston has moved towards said first chamber by a distance sufficient to enable said skirt to seat against said shoulder.
Claim 8
Dependent Claim
64 words
An actuator assembly as claimed in claim 6, wherein said cup-shaped piston is slidable guided in a portion of said differential piston of smaller diameter which projects into the portion of said stepped bore of greater diameter, and there is a clearance between an outer peripheral edge of said cup-shaped piston and the wall of said portion of said stepped bore of greater diameter.
Claim 9
Dependent Claim
194 words
An actuator assembly as claimed in claim 4, including a third inlet connection in said housing leading to said second chamber, wherein a one-way valve assembly is housed in each of said second and third connections, each one-way valve assembly incorporating a valve member, a seating surrounding an orifice and adapted to be engaged by said valve member and spring means for urging said valve member into engagement with said seating, said one-way valve assemblies being constructed and arranged to operate in opposite directions whereby high pressure fluid is adapted to be supplied to both connections but is applied to said actuator piston only through said one-way valve which opens in that direction, fluid from said actuator piston being returned from said second chamber upon re-application of a wheel brake through said other one-way valve and said connection in which that one-way valve is located, whereby the delay in the re-application of a wheel brake after the deceleration of the wheel has been restored to a predetermined value is controlled by the return of fluid from said actuator piston to the control valve through said orifice in said one-way valve in the return connection.
Claim 10
Dependent Claim
49 words
An actuator assembly as claimed in claim 8 wherein each orifice is provided in a plate which is interchangeable with a series of similar plates having orifices of different diameters whereby the rate of flow fluid in each connection can be varied in accordance with a desired braking characteristic.
Claim 11
Dependent Claim
73 words
An actuator assembly as claimed in claim 3, wherein the movable member is a third piston working in said recess in said end of said actuator piston of greater diameter and having an inner end, wherein said inner end of said third piston defines with said base of said recess forming the first area a third chamber into which hydraulic fluid under pressure is admitted through an axial bore in said third piston.
Claim 12
Dependent Claim
34 words
An actuator assembly as claimed in claim 1 incorporating means for delaying re-application of a wheel brake following cut-off and relief of the supply of fluid to a slave cylinder from said outlet connection.
Claim 13
Dependent Claim
31 words
An actuator assembly as claimed in claim 1, wherein said piston assembly comprises a single expander piston working in a bore in said housing and controlled by a single actuator piston.
Claim 14
Dependent Claim
85 words
An actuator assembly as claimed in claim 1, wherein said piston assembly comprises at least two expander pistons working in separate parallel bores in said housing, said expander pistons being controlled by single actuator piston, and each expander piston being adapted to control the effective volume of a chamber provided with separate inlet and outlet connections and operation of a spring loaded valve means for controlling communication between said inlet connection and said chamber of which the effective volume is variable by that expander piston.
Claim 15
Dependent Claim
42 words
An actuator assembly as claimed in claim 1, wherein said piston assembly comprises a two part axially separable assembly adapted to regulate the effective volume of a first and second axially spaced chamber, each provided with an inlet and an outlet connection.
Claim 16
Dependent Claim
100 words
An actuator assembly as claimed in claim 14, wherein said first axially spaced chamber is located at the end of said bore in which works said expander piston and into which a free end portion of a first part of said separable assembly eXtends, and adjacent to the opposite end of said first part is formed an axially extending annular recess with which an adjacent end of a second part of said separable assembly defines said second axially spaced chamber of which the effective volume is variable upon relative axial movement between said first and second parts of separable assembly.
Claim 17
Dependent Claim
102 words
An actuator assembly as claimed in claim 15 wherein communication between said inlet and outlet connections with said first axially spaced chamber is controlled by a valve operable by a push-rod carried by the free end of said first part of said separable assembly, and communication between said inlet and outlet connections with said second axially spaced chamber is controlled by a spring loaded tipping valve which is normally held in an open position by the engagement of a stem of the tipping valve with a shoulder at the end of said recess adjacent to said second part of the separable assembly.
References Cited (Backward Citations)
US3544171A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-09-26 | 1976-03-27 | 1976-09-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-26 | 1980-03-27 | 1980-09-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-26 | 1984-03-27 | 1984-09-26 | $7700.00 | Window Closed / Lapsed |