US3758235A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Power transmission
Assignee: Vickers Inc
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Filing: 1971-09-22
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Granted: 1973-09-11
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Expires: 1991-09-22
Abstract
Abstract A displacement adjusting system for a variable displacement pump utilizes a pair of bleed circuits connected as a hydraulic bridge to control the servomotor of the pump so as to maintain a balance between the pressure levels generated in the command bleed circuit and in the feedback bleed circuit. The adjustable restriction in the feedback circuit is of the laminar flow type, its length being adjusted with changes in pump displacement. Input torque is limited by a relief valve acting on the control pressure in the command circuit. Pump outlet pressure is limited by a valve which disables the bleed circuits. The system is applicable to both one-way and reversible displacement pumps.
Inventors
- 👤 R Breeden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:28
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/42; F16H61/433; F04; F04B; F04B49/00; F04B49/002; F04B49/08
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
128 words
A displacement adjusting system for a variable displacement pump or motor unit comprising a member shiftable to change the unit displacement, hydraulic servomotor means to shift the member, a source of control pressure fluid, oppositely acting means for controlling the servomotor including a pair of bleed circuits extending from the fluid pressure source, one bleed circuit constituting the command circuit and having restricting means for generating a controlling pressure at any commanded level, the other bleed circuit constituting the feedback circuit and having laminar flow restrictions of variable length connected to the shiftable member for generating an opposing controlling pressure at a level responsive to the position of the shiftable member, whereby the unit displacement may be adjusted by changing the degree of restriction in the command circuit.
Claim 2
Dependent Claim
128 words
A displacement adjusting system for a variable displacement pump or motor unit comprising a member shiftable to change the unit displacement, hydraulic servomotor means to shift the member, a source of control pressure fluid, oppositely acting means for controlling the servomotor including a pair of bleed circuits extending from the fluid pressure source, one bleed circuit constituting the command circuit and having restricting means for generating a controlling pressure at any commanded level, the other bleed circuit constituting the feedback circuit and having laminar flow restrictions of variable length connected to the shiftable member for generating an opposing controlling pressure at a level responsive to the position of the shiftable member, whereby the unit displacement may be adjusted by changing the degree of restriction in the command circuit.
Claim 3
Dependent Claim
28 words
A system as defined in claim 1 wherein the means for controlling the servomotor includes a pilot valve responsive to the opposing pressures generated in the bleed circuits.
Claim 4
Dependent Claim
21 words
A system as defined in claim 1 wherein the bleed circuits are supplied from the high pressure side of the unit.
Claim 5
Dependent Claim
55 words
A system as defined in claim 3 wherein a pressure responsive valve is connected to limit the pressure level in the command circuit whereby the maximum torque input to the pump may be limited by the combined variations in pump outlet pressure and pump displacement as reflected in the pressure level in the feedback circuit.
Claim 6
Dependent Claim
31 words
A system as defined in claim 4 including means for adjusting the action of the pressure responsive valve whereby to change the input torque level to which the pump is limited.
Claim 7
Dependent Claim
44 words
A system as defined in claim 1 having means responsive to the achieving of a selected maximum pressure at the pump outlet for delivering fluid from the pump outlet to the servomotor directly and independently of the control pressure levels in the bleed circuit.
Claim 8
Dependent Claim
44 words
A system as defined in claim 3 having means responsive to the achieving of a selected maximum pressure at the pump outlet for delivering fluid from the pump outlet to the servomotor directly and independently of the control pressure levels in the bleed circuits.
Claim 9
Dependent Claim
40 words
A system as defined in claim 1 wherein the pump displacement is both variable and reversible across a neutral setting and a second pair of similar bleed circuits are provided to control the servomotor on the opposite side of neutral.
Claim 10
Dependent Claim
25 words
A system as defined in claim 8 including a pair of shuttle valves for controlling the action of the respective bleed circuits upon the servomotor.
Claim 11
Dependent Claim
27 words
A system as defined in claim 1 wherein the laminar flow restrictions are mutually variable, an increase in one resulting in a corresponding decrease in the other.
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) | 1976-09-10 | 1977-03-12 | 1977-09-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-10 | 1981-03-12 | 1981-09-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-10 | 1985-03-12 | 1985-09-11 | $7700.00 | Window Closed / Lapsed |