US4062329A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fan drive system
Assignee: United States Department of the Army
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Filing: 1976-07-29
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Granted: 1977-12-13
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Expires: 1996-07-29
Abstract
Abstract A variable speed fan drive mechanism for an engine coolant system control by temperature and fan speed signals. The mechanism includes a hydrostatic pump-motor unit (hydrostatic transmission) powered by the engine, for transmitting power to the fan. Mechanical signals related to coolant temperature and fan speed are supplied to a comparator mechanism that delivers a mechanical output control signal. The output control signal is magnified and applied as a control force to vary the displacement of the pump in the hydrostatic unit. The comparator mechanism has the effect of negating engine speed as a control force. Thus, high engine speeds (that would tend to produce unduly large hydraulic flows through the pump-motor circuit) are reflected in high fan speed signals fed into the comparator mechanism, which produces a "corrected" output signal that appropriately reduces pump dislacement to thus reduce the fan speed to low energy consumption levels.
Inventors
- 👤 Russell L. Rio
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 04:38
CPC Classifications
F; F01; F01P; F01P7/00; F01P7/02; F01P7/04; F01P7/044
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
238 words
In an engine cooling system that includes a fan for cooling the engine coolant: means for driving the fan at variable speed, comprising a hydrostatic transmission that includes a variable displacement pump (10) driven by the engine to produce a hydraulic output 13, a fixed displacement fan motor (12) receiving the pump output (13), and a hydraulic return line (at 19,21) interconnecting the motor and pump; control means for the aforementioned driving means, comprising first thermostatic means (17) responsive to engine temperature for developing a first positive control signal (at 39), a flow-responsive element (23) arranged in the aforementioned hydraulic return line for developing a second negative control signal (at 40), comparator means (37) receiving the first and second signals, said comparator means producing an output signal (at 36) representing the differential between the first and second signals, and means for applying said output signal to the aforementioned pump (10) to vary its displacement, whereby said motor (12) drives the fan at varying speeds sufficient to maintain a substantially uniform engine temperature under a range of operating conditions; a second engine-driven make-up pump (41) having a relatively small output that is directly related to engine speed, and conduit means (43) directing the pump (41) output to the aforementioned return line at a point upstream from the aforementioned flow-responsive element (23), whereby said element (23) produces a signal that is related both to fan motor speed and engine speed.
Claim 2
Dependent Claim
238 words
In an engine cooling system that includes a fan for cooling the engine coolant: means for driving the fan at variable speed, comprising a hydrostatic transmission that includes a variable displacement pump (10) driven by the engine to produce a hydraulic output 13, a fixed displacement fan motor (12) receiving the pump output (13), and a hydraulic return line (at 19,21) interconnecting the motor and pump; control means for the aforementioned driving means, comprising first thermostatic means (17) responsive to engine temperature for developing a first positive control signal (at 39), a flow-responsive element (23) arranged in the aforementioned hydraulic return line for developing a second negative control signal (at 40), comparator means (37) receiving the first and second signals, said comparator means producing an output signal (at 36) representing the differential between the first and second signals, and means for applying said output signal to the aforementioned pump (10) to vary its displacement, whereby said motor (12) drives the fan at varying speeds sufficient to maintain a substantially uniform engine temperature under a range of operating conditions; a second engine-driven make-up pump (41) having a relatively small output that is directly related to engine speed, and conduit means (43) directing the pump (41) output to the aforementioned return line at a point upstream from the aforementioned flow-responsive element (23), whereby said element (23) produces a signal that is related both to fan motor speed and engine speed.
Claim 3
Dependent Claim
50 words
The system of claim 1: said comparator means comprising a balancing arm structure (37) located to receive the first control signal at one of its ends and the second control signal at its other end; the balancing arm structure producing the aforementioned output signal at a point intermediate its ends.
Claim 4
Dependent Claim
27 words
The system of claim 1: and further comprising force-multiplication means (at 30,26) for increasing the magnitude of the output signal before application thereof to the pump (10).
Claim 5
Dependent Claim
68 words
The system of claim 3: said force-multiplication means comprising a flow-apportioning valve (30) mechanically connected to the balancing arm structure, and a hydraulic piston (26) connected to the aforementioned pump (10); said apportioning valve being hydraulically connected to the aforementioned return line to selectively direct pressure liquid against opposite faces of the hydraulic piston in accordance with small mechanical forces applied to the valve by the arm structure.
References Cited (Backward Citations)
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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) | 1980-12-12 | 1981-06-13 | 1981-12-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-12-12 | 1985-06-13 | 1985-12-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-12-12 | 1989-06-13 | 1989-12-13 | $7700.00 | Window Closed / Lapsed |