Heat exchange – Movable heating or cooling surface – Rotary drum
Patent
1981-12-17
1984-12-11
Focarino, Margaret A.
Heat exchange
Movable heating or cooling surface
Rotary drum
236 35, 123 4112, 417213, 60445, F01P 702
Patent
active
044872550
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
Technical Field
This invention relates generally to a control for a fluid-driven fan and more particularly to a control arrangement for controlling the displacement of a variable displacement pump for controlling the speed of the fluid-driven fan in a vehicle.
Background Art
Fluid-driven fan systems make it possible to cool a heat exchanger on a vehicle remote from the engine. Most normally include a fan connected to a fluid motor with the fluid motor being driven by fluid from a variable displacement pump. Many of the systems use a signal representative of the temperature in the heat exchanger for changing the rate of flow to the motor. It is desirable to run the fan at a low speed when the temperature in the heat exchanger is below a predetermined level. The reduction of the flow from the pump when not needed reduces the horsepower consumed by the vehicle. For the protection of the operator and/or maintenance personnel, the fan should be turning when the engine is running. It would also be advantageous to reduce the pressure of the fluid from the pump during the low speed condition to further reduce horsepower consumption. The problem encountered, especially with larger motors, is the inability to start the motor turning when the engine is started with the pump at reduced flow and pressure.
The present invention is directed to overcoming one or more of the problems as set forth above.
Disclosure of the Invention
In one aspect of the present invention, a fan drive system has a fluid motor connected to a cooling fan with a variable displacement pump supplying fluid from a tank to drive the fluid motor. The variable displacement pump has a fluid control actuator to vary the pump's displacement. The cooling fan delivers air to a heat exchanger for cooling the heat exchanger. A means 32 is provided for changing the displacement of the pump 12 to operate at a first operative displacement position for a predetermined time period from initial start-up and automatically reducing the displacement of the pump to a second, standby displacement position at the expiration of the predetermined time period.
This invention solves the problem of the fan motor not starting when the engine is started in a system having a variable displacement pump which has low flow and pressure when the temperature of the heat exchanger is below the predetermined level. The control mechanism of this invention delivers a control signal to the control actuator of the variable displacement pump for initially adjusting the pump to deliver fluid to the motor at a pressure and flow sufficient for turning the motor and subsequently interrupting the control signal to reduce the pressure and flow of the pump. This results in a more energy efficient fan drive system while ensuring fan rotation at all times during engine operation.
Brief Description of the Drawings
The drawing is a schematic representation of an embodiment of the present invention.
Best Mode for Carrying Out the Invention
Referring now to the drawing, a fluid-driven fan drive system is generally indicated by reference numeral 10 and includes a variable displacement pump 12 connected to a tank or reservoir 14. A fluid control actuator 15 controls the flow and pressure of the pump 12. A fluid driven motor 16 is connected to the pump 12 by a conduit 18 and to the tank 14 by a conduit 20.
An output shaft 24 connects a cooling fan 22 to the motor 16 in a conventional manner. A heat exchanger 26 is mounted adjacent the cooling fan 22. A temperature sensor means 28 is located in the heat exchanger 26 for sensing the temperature in the heat exchanger and generating a signal 29 in response to the temperature exceeding a predetermined level. An oil cooler 30 and a by-pass relief valve 31 are connected to the conduit 20 in a conventional manner and located on a vehicle (not shown) adjacent the heat exchanger 26.
A means 32 is provided for changing the displacement of the pump 12 to operate at a first operative displacement position for a predetermined time period fro
REFERENCES:
patent: 3664129 (1972-05-01), Schwab
patent: 3797245 (1974-03-01), Hein
patent: 3942486 (1976-03-01), Kirchner
patent: 3995425 (1976-12-01), Wittren
patent: 4036432 (1977-07-01), George
patent: 4062329 (1977-12-01), Rio
patent: 4066047 (1978-01-01), Vidakovic et al.
patent: 4200146 (1980-04-01), Olson
patent: 4223646 (1980-09-01), Kinder
patent: 4373869 (1983-02-01), Martin et al.
Bianchetta Donald L.
White Robert W.
Burrows J. W.
Caterpillar Tractor Co.
Focarino Margaret A.
LandOfFree
Control for a fluid-driven fan does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Control for a fluid-driven fan, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control for a fluid-driven fan will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1458536