US3732041A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Power transmission
Assignee: Vickers Inc
•
Filing: 1971-06-10
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Granted: 1973-05-08
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Expires: 1991-06-10
Abstract
Abstract A pump for use in a hydraulic power transmission system has a servomotor for varying its displacement which is controlled by a valve responsive to delivery line pressure of the pump. The valve, in turn, is controlled both by a spring which determines a minimum level of delivery pressure and by a piston responsive to the pressure level in a bleed circuit. The bleed circuit includes a fixed restriction and an electrically modulated flapper valve so that the pressure level in the pump delivery line may be modulated by adjustment of the current flowing through the coil of the electrically modulated flapper valve.
Inventors
- 👤 T Beal
- 👤 J Curnow
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 11:26
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/42; F16H61/437; F04; F04B; F04B1/00; F04B1/12; F04B1/26; F04B1/30; F04B1/32; F04B1/324; F04B49/00; F04B49/06; F04B49/08; F15; F15B; F15B13/00; F15B13/02; F15B13/04; F15B13/042; F15B13/043; F16H61/46; F16H61/472
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
152 words
An electrically modulated hydraulic pump having a servomotor arranged to vary the pump displacement, a control valve connected to inject or withdraw pressure fluid into or out of the servomotor, means connected to operate the valve to modulate the delivery pressure of the pump comprising a sensing piston and cylinder connected to the delivery side of the pump, a spring opposing the sensing piston and cylinder, a second sensing piston and cylinder opposing the first one, and electrically operated means for supplying fluid to the second piston and cylinder at any selected pressure level below the delivery pressure of the pump, said electrically operated means comprising an electromagnet and a flapper valve responsive to the current supplied to the electromagnet, duct means for bleeding a small flow of pressure fluid from the pump delivery through the flapper valve and a fixed restriction in the duct means in series with the flapper valve.
Claim 2
Dependent Claim
152 words
An electrically modulated hydraulic pump having a servomotor arranged to vary the pump displacement, a control valve connected to inject or withdraw pressure fluid into or out of the servomotor, means connected to operate the valve to modulate the delivery pressure of the pump comprising a sensing piston and cylinder connected to the delivery side of the pump, a spring opposing the sensing piston and cylinder, a second sensing piston and cylinder opposing the first one, and electrically operated means for supplying fluid to the second piston and cylinder at any selected pressure level below the delivery pressure of the pump, said electrically operated means comprising an electromagnet and a flapper valve responsive to the current supplied to the electromagnet, duct means for bleeding a small flow of pressure fluid from the pump delivery through the flapper valve and a fixed restriction in the duct means in series with the flapper valve.
Claim 3
Dependent Claim
35 words
A pump as defined in claim 1 wherein the restriction is upstream of the flapper valve and a branch passage is connected from ahead of the flapper valve to the second sensing piston and cylinder.
References Cited (Backward Citations)
US3252419A
Cited
US3286601A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-05-07 | 1976-11-06 | 1977-05-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-07 | 1980-11-06 | 1981-05-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-07 | 1984-11-06 | 1985-05-08 | $7700.00 | Window Closed / Lapsed |