Patent US3987626A successfully refreshed from Google Patents.
US3987626A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Controls for multiple variable displacement pumps
Assignee: Caterpillar Inc
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Filing: 1976-01-23
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Granted: 1976-10-26
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Expires: 1996-01-23
Abstract
Abstract Fluid is selectively, controllably delivered at substantially common rates from separate respective variable displacement pumps in response to a load pressure signal acting on a single pump control valve serving said pumps.
Inventors
- 👤 Donald L. Bianchetta
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 07:07
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/42
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
124 words
Controls for controllably maintaining substantially common discharge rates from at least first and second variable displacement pumps, comprising: means for sensing the discharge pressure of each pump and delivering a first control signal responsive to the larger of said sensed discharge pressures; means for sensing the load pressure of each work element and delivering a second control signal responsive to the larger of said sensed load pressures; control means for altering the first control signal and delivering a resultant third control signal, said first control signal being altered in response to a preselected biasing force and the second control signal acting in opposition to the first control signal; and means for controlling the displacement of each pump in response to said third control signal.
Claim 2
Dependent Claim
124 words
Controls for controllably maintaining substantially common discharge rates from at least first and second variable displacement pumps, comprising: means for sensing the discharge pressure of each pump and delivering a first control signal responsive to the larger of said sensed discharge pressures; means for sensing the load pressure of each work element and delivering a second control signal responsive to the larger of said sensed load pressures; control means for altering the first control signal and delivering a resultant third control signal, said first control signal being altered in response to a preselected biasing force and the second control signal acting in opposition to the first control signal; and means for controlling the displacement of each pump in response to said third control signal.
Claim 3
Dependent Claim
66 words
Apparatus, as set forth in claim 1, wherein the discharge pressure sensing signaling means comprises: first and second conduits each being in communication with fluid discharging from respective first and second pumps; first and second discharge check valves positioned in respective first and second conduits and being commonly oriented; and means communicating said first and second conduits at a location downstream of the discharge check valves.
Claim 4
Dependent Claim
126 words
Apparatus, as set forth in claim 1, wherein the load pressure sensing signaling means comprises: first and second work elements; a pair of first and second hydraulic fluid conduits each connected to a separate pump and to a respective work element for selective passage of fluid from each pump to its respective work element; first and second resolver valves each in fluid communication with respective said first and second conduits; first and second signal conduits each connected at one end to a respective resolver valve; first and second load pressure check valves each positioned in a respective first and second signal conduit and being commonly oriented; and means for communicating said first and second signal conduits at a location downstream of the load pressure check valves.
Claim 5
Dependent Claim
50 words
Apparatus, as set forth in claim 1, wherein the signal altering control means comprises: a spool valve having a first end in communication with the first control signal and the second end in communication with the second control signal and being biased toward the first end by a biasing means.
Claim 6
Dependent Claim
70 words
Apparatus, as set forth in claim 1, wherein each pump has a swash plate and the displacement control means of each pump comprises: a servo motor having a spool valve and biasing means for biasing the spool valve in a first direction; and means for communicating the third control signal with the spool valve and urging the spool valve in a preselected direction in response to said third control signal.
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) | 1979-10-26 | 1980-04-26 | 1980-10-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-10-26 | 1984-04-26 | 1984-10-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-10-26 | 1988-04-26 | 1988-10-26 | $7700.00 | Window Closed / Lapsed |