Patent US3877839A successfully refreshed from Google Patents.
US3877839A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Torque limiting means for variable displacement pumps
Assignee: Individual
•
Filing: 1973-10-03
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Granted: 1975-04-15
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Expires: 1993-10-03
Abstract
Abstract The loading of rotor support journals, of variable displacement pumps, which is proportional to the theoretical driving torque of the pump, is converted to a fluid pressure which is proportional to the theoretical pump driving torque. The fluid pressure is applied to a plunger in opposition to an adjustable load, to operate a servo valve to regulate the pump displacement. The loading may be varied to provide variations in the pump driving torques to correspond to the torques available from a prime mover under a variety of power settings.
Inventors
- 👤 Richard Joseph Ifield
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 23:56
CPC Classifications
F; F04; F04B; F04B49/00; F04B49/002; F04B1/00; F04B1/12; F04B1/20; F04B1/2014; F04B1/2064; F04B1/2071; F04B1/26; F04B1/30; F04B1/32; F04B1/324; F04B49/08; F02; F02B; F02B1/00; F02B1/02; F02B1/04
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
62 words
In a variable displacement piston pump including a driven rotor, torque limiting means, for limiting the driving torque of the pump, comprising, in combination, a hydrostatically balanced slipper bearing supporting the pump rotor, pressure responsive means operable to regulate a pump displacement, and means transmitting the hydrostatic bearing pressure to said pressure responsive means to effect operation of said pressure responsive means.
Claim 2
Dependent Claim
62 words
In a variable displacement piston pump including a driven rotor, torque limiting means, for limiting the driving torque of the pump, comprising, in combination, a hydrostatically balanced slipper bearing supporting the pump rotor, pressure responsive means operable to regulate a pump displacement, and means transmitting the hydrostatic bearing pressure to said pressure responsive means to effect operation of said pressure responsive means.
Claim 3
Dependent Claim
59 words
Torque limiting means according to claim 1, wherein said pressure responsive means comprise a pilot valve device including a moving element responsive to the bearing pressure in opposition to a resilient loading, a servo motor controlling the pump discharge and a servo control valve operated in consequence of the operation of said pilot valve and controlling said servo motor.
Claim 4
Dependent Claim
67 words
Torque limiting means according to claim 2, in which the pump is driven by a prime mover, and means controlling the torque as a function of the speed of the prime mover including means applying a fixed negative load to said moving element in combination with means applying, to said movable element, a load varying as a function of the prime mover speed and power control setting.
Claim 5
Dependent Claim
56 words
Torque limiting means according to claim 2, including a stabilising device comprising a piston in a cylinder device connected to the servo motor to produce a fluid pressure varying as a function of the rate of change of the pump displacement and acting on the pilot valve loading to enhance the stability of the control system.
Claim 6
Dependent Claim
49 words
Torque limiting means according to claim 2, wherein operation of said pilot valve overrides the effect of the other control means acting on the servo valve so as to limit the pump driving torque by variation of the pump displacement irrespective of the setting of said other control means.
Claim 7
Dependent Claim
90 words
Torque limiting means according to claim 5, wherein said servo valve is a direction control selector valve, having an axially moveable spool such that, at one limit of the spool axial travel, the servo valve controls the servo motor in response to the setting of said other control means whereas, at the other limit of the spool axial travel, the servo valve causes the servo motor to reduce pump capacity; the spool being moved to said other limit by a pressure change in consequence of operation of said pilot valve.
Claim 8
Dependent Claim
51 words
Torque limiting means according to claim 6, wherein said servo valve is a combined manual and automatic displacement and directional control selector valve, comprising a manually operated, ported sleeve and a rotary spool driven by the servo motor and subject to axial displacement in consequence of operation of said pilot valve.
Claim 9
Dependent Claim
34 words
Torque limiting means according to claim 5, wherein said pilot valve comprises a bearing pressure responsive plunger, bearing against a springloaded valve element, the springload being mechanically adjustable to regulate the maximum torque value.
References Cited (Backward Citations)
US3155047A
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US3407738A
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US3726609A
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US3733963A
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US3750532A
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US3803987A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-14 | 1978-10-14 | 1979-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-14 | 1982-10-14 | 1983-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-14 | 1986-10-14 | 1987-04-15 | $7700.00 | Window Closed / Lapsed |