US3861145A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multiple hydraulic control circuits with pressure compensated flow control and a single variable delivery pump
Assignee: Caterpillar Inc
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Filing: 1973-10-01
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Granted: 1975-01-21
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Expires: 1993-10-01
Abstract
Abstract A fluid delivery system is provided having multiple hydraulic control circuits and a variable displacement pump controlled by a pressure compensated servo control which is responsive to circuit pressure for regulating pump displacement and thus provide pump output commensurate with demand from the load circuits. A control mechanism including a control valve has a pair of variable orifices in series which are created by the main control valve spool and a pressure compensated flow control spool in serial arrangement therewith precisely controls the fluid volume flow to a load system in proportion to the opening of the variable orifices. A pressure compensated servo control is adapted to move the swash plate of the pump to a minimum displacement position when all of the closed center control valves are in neutral position thereby minimizing engine horsepower loss while maintaining sufficient system pressure to provide immediate response when one of the control valves is opened.
Inventors
- 👤 Gerald D Hall
- 👤 Allyn J Hein
- 👤 Howard L Johnson
- 👤 John A Junck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 05:21
CPC Classifications
F; F15; F15B; F15B13/00; F15B13/02; F15B13/04; F15B13/0416; F15B13/0417
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
209 words
A fluid delivery system including, a variable displacement pump having an inlet and an outlet for delivering fluid under pressure, a pair of load circuits connected to said outlet, a servo control means connected to said pump which is responsive to load circuit pressure for regulating the displacement of said pump and thereby provide pump output commensurate with the demand of the load circuits, and wherein each load circuit comprises, a load, and control valve means comprising a body, flow control spool means in said body for modulating communication between said outlet and main control spool means including a main control spool slidably located within a second bore in said body and a second spring means biasing said main control spool to a neutral position closing off communication between said flow control spool means and said load, said main control spool having means thereon which are operable to provide a variable orifice intermediate said flow control spool means and said load, and wherein said control valve means is actuable from a neutral position to direct fluid under pressure from said outlet to said load, said control valve means providing pressure compensated flow control whereby immediate response is provided when said control valve means is moved from the neutral position.
Claim 2
Dependent Claim
209 words
A fluid delivery system including, a variable displacement pump having an inlet and an outlet for delivering fluid under pressure, a pair of load circuits connected to said outlet, a servo control means connected to said pump which is responsive to load circuit pressure for regulating the displacement of said pump and thereby provide pump output commensurate with the demand of the load circuits, and wherein each load circuit comprises, a load, and control valve means comprising a body, flow control spool means in said body for modulating communication between said outlet and main control spool means including a main control spool slidably located within a second bore in said body and a second spring means biasing said main control spool to a neutral position closing off communication between said flow control spool means and said load, said main control spool having means thereon which are operable to provide a variable orifice intermediate said flow control spool means and said load, and wherein said control valve means is actuable from a neutral position to direct fluid under pressure from said outlet to said load, said control valve means providing pressure compensated flow control whereby immediate response is provided when said control valve means is moved from the neutral position.
Claim 3
Dependent Claim
41 words
The system of claim 1 wherein said flow control spool means comprises a flow control spool slidably located within a first bore in said body and a first spring means biasing said flow control spool to a position providing said communication.
Claim 4
Dependent Claim
157 words
A fluid delivery system including, a variable displacement pump including a pump housing, and having an inlet and an outlet for delivering fluid under pressure, a pair of load circuits connected to said outlet, a servo control means connected to said pump which is responsive to load circuit pressure for regulating the displacement of said pump and thereby provide pump output commensurate with the demand of the load circuits, wherein said servo control means comprise first and second servo control cartridges at least partially within said housing for moving a swash plate pivotally mounted within said pump housing so as to control pump displacement, and wherein each load circuit comprises, a load, and control valve means actuable from a neutral position to direct fluid under pressure from said outlet to said load, said control valve means providing pressure compensated flow control whereby immediate response is provided when said valve control means is moved from the neutral position.
Claim 5
Dependent Claim
157 words
A fluid delivery system including, a variable displacement pump including a pump housing, and having an inlet and an outlet for delivering fluid under pressure, a pair of load circuits connected to said outlet, a servo control means connected to said pump which is responsive to load circuit pressure for regulating the displacement of said pump and thereby provide pump output commensurate with the demand of the load circuits, wherein said servo control means comprise first and second servo control cartridges at least partially within said housing for moving a swash plate pivotally mounted within said pump housing so as to control pump displacement, and wherein each load circuit comprises, a load, and control valve means actuable from a neutral position to direct fluid under pressure from said outlet to said load, said control valve means providing pressure compensated flow control whereby immediate response is provided when said valve control means is moved from the neutral position.
Claim 6
Dependent Claim
39 words
The system of claim 3 wherein said first servo control cartridge includes a piston housed within a bore therein, said piston extending from an end of said first cartridge in contacting relation with said swash plate for movement thereof.
Claim 7
Dependent Claim
45 words
The system of claim 4 wherein said second control cartridge includes a second piston housed within a bore therein and extending from an inner end of said second cartridge in contacting relation with said swash plate for movement thereof in opposition to said first cartridge.
Claim 8
Dependent Claim
44 words
The system of claim 5 wherein said second cartridge further comprises a first longitudinal bore and a coaxial, enlarged inner bore adjacent said inner end, a slidable sleeve disposed in said first bore, and a stop plate in the inner end of said sleeve.
Claim 9
Dependent Claim
28 words
The system of claim 6 wherein said second cartridge further comprises a follow up plunger connected to said second piston and slidably mounted in said enlarged, inner bore.
Claim 10
Dependent Claim
51 words
The system of claim 7 wherein said second cartridge further comprises a sleeve spool within said sleeve, and spring means biasing said sleeve spool into engagement with said stop plate, said sleeve spool including a plurality of metering slots thereon communicating with a plurality of radiallly directed ports in said sleeve.
Claim 11
Dependent Claim
32 words
The system of claim 1 further including relief valve means for relieving over pressure from said outlet to a reservoir thereby limiting maximum working pressure in the system to a desired value.
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) | 1978-01-20 | 1978-07-22 | 1979-01-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-20 | 1982-07-22 | 1983-01-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-20 | 1986-07-22 | 1987-01-21 | $7700.00 | Window Closed / Lapsed |