US3559669A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic control system for brakes, clutches and the like
Assignee: ZF Friedrichshafen AG
•
Filing: 1968-12-20
•
Granted: 1971-02-02
•
Expires: 1988-12-20
Abstract
Abstract A pair of hydraulic loads in the form of clutches and/or brakes are controlled by a common valve having separate inlet ports for high-pressure fluid and associated outlet ports respectively connected to these loads, each inlet port communicating with its associated outlet port in an initial position of a slider which, in response to pressure buildup in the first outlet port, shifts into an alternate position in which the fluid supply to the first load is reduced and the supply to the second load is substantially cutoff, this shift occurring against a biasing force of a spring bearing upon a piston which is displaceable by hydraulic fluid from the first outlet port, delivered through a constricted passage, to augment the biasing force so as to reestablish the initial position after a further pressure rise at the first load, thereby admitting fluid to both loads at substantially the pressure prevailing at the two inlet ports.
Inventors
- 👤 Hansjorg Dach
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 04:36
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/04; F16H61/06; F16H61/065; F16H61/067; F16D; F16D67/00; F16D67/02; F16D67/04; Y; Y10; Y10T; Y10T137/00; Y10T137/2496; Y10T137/2544
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
213 words
In a fluid-operated load-control system, in combination: a first and a second fluid-actuatable load; valve means comprising a housing with a first and a second inlet port separately connectable to a supply of high-pressure operating fluid, a first outlet port connected to said first load, and a second outlet port connected to said second load, said valve means having a normal position connecting said first inlet port with said first outlet port and said second inlet port with said second outlet port, said valve means being provided with a land facing said first inlet port for displacement by the supply pressure thereof into an off-normal position wherein said valve means restricts the flow of fluid to said first outlet port and substantially cuts off said second outlet port from said second inlet port, with establishment of a gradually rising operating pressure lower than said supply pressure at said first outlet port; biasing means opposing such displacement of said valve means by said supply pressure; and throttled conduit means extending from said first outlet port to said biasing means for exerting thereon a force-increasing action in response to a predetermined rise in said operating pressure, thereby restoring said valve means to said normal position and reestablishing communication between said second inlet and outlet ports.
Claim 2
Dependent Claim
213 words
In a fluid-operated load-control system, in combination: a first and a second fluid-actuatable load; valve means comprising a housing with a first and a second inlet port separately connectable to a supply of high-pressure operating fluid, a first outlet port connected to said first load, and a second outlet port connected to said second load, said valve means having a normal position connecting said first inlet port with said first outlet port and said second inlet port with said second outlet port, said valve means being provided with a land facing said first inlet port for displacement by the supply pressure thereof into an off-normal position wherein said valve means restricts the flow of fluid to said first outlet port and substantially cuts off said second outlet port from said second inlet port, with establishment of a gradually rising operating pressure lower than said supply pressure at said first outlet port; biasing means opposing such displacement of said valve means by said supply pressure; and throttled conduit means extending from said first outlet port to said biasing means for exerting thereon a force-increasing action in response to a predetermined rise in said operating pressure, thereby restoring said valve means to said normal position and reestablishing communication between said second inlet and outlet ports.
Claim 3
Dependent Claim
59 words
The combination defined in claim 1 wherein said biasing means comprises a piston with a face larger than said land and a compression spring interposed between said valve means and said piston, said housing forming a cylinder for said piston with a fluid space remote from said spring adjacent said face, said conduit means opening into said fluid space.
Claim 4
Dependent Claim
54 words
The combination defined in claim 2 wherein said cylinder is provided with an additional port communicating with a source of variable fluid pressure less than said supply pressure bearing upon said piston to modify the magnitude of said predetermined rise in said operating pressure, said piston separating said additional port from said conduit means.
Claim 5
Dependent Claim
46 words
The combination defined in claim 2 wherein said valve means comprises a slider coaxial with said piston, said slider and said piston being provided with cooperating formations interengageable in a position of maximum compression of said spring for positively restoring said slider to its normal position.
Claim 6
Dependent Claim
80 words
The combination defined in claim 4 wherein said slider is provided with three spaced-apart heads defining a first recess cooperating with said first inlet and outlet ports and a second recess cooperating with said second inlet and outlet ports, said housing further having a discharge port normally obstructed by one of said heads and positioned to be at least partly unblocked thereby for communication with said first recess in said off-normal position to control the magnitude of said operating pressure.
Claim 7
Dependent Claim
34 words
The combination defined in claim 5 wherein said housing forms a bore for said slider with a restricted pressure-equalizing connection from said first outlet to a location confronting the head farthest from said position.
Claim 8
Dependent Claim
34 words
The combination defined in claim 2 wherein said cylinder is provided with unidirectionally effective venting means extending to said first outlet port from a location obstructed by said position in a retracted position thereof.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-02-01 | 1974-08-03 | 1975-02-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-01 | 1978-08-03 | 1979-02-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-01 | 1982-08-03 | 1983-02-02 | $7700.00 | Window Closed / Lapsed |