Continuosly variable fan drive clutch

• US 5,937,979 A
• Filed: 04/21/1997
• Issued: 08/17/1999
• Est. Priority Date: 09/18/1995
• Status: Expired due to Term

• Current Assignee: Rockford Powertrain, Inc. (Melrose Industries Plc)
• Original Assignee: Rockford Powertrain, Inc. (Melrose Industries Plc)
• Inventors: Cummings, Gordon F.
• Primary Examiner(s): Lorence, Richard M.
• Application Number:
  US08/840,483
• Time in Patent Office: 848 Days
• Field of Search: 192/18 A, 192/12 C, 192/58.42, 192/70.12, 192/85 CA, 192/82 T, 192/103 F, 192/113.34, 123/41.12, 416/169 A
• US Class Current: 192/18.00A
• CPC Class Codes: F01P 2025/04 Pressure
• CPC Class Codes: F01P 2025/08 Temperature
• CPC Class Codes: F01P 2025/13 Ambient temperature
• CPC Class Codes: F01P 2025/40 Oil temperature
• CPC Class Codes: F01P 7/04 by varying pump speed, e.g. by changing pump-drive gear ratio
• CPC Class Codes: F01P 7/046 using mechanical drives
• CPC Class Codes: F01P 7/088 actuated in response to driving speed, e.g. by centrifugal devices
• CPC Class Codes: F16D 2065/024 the braking surface being inclined with respect to the rotor's axis of rotation at an angle other than 90 degrees, e.g. comprising a conical rotor
• CPC Class Codes: F16D 25/082 the line of action of the fluid-actuated members co-inciding with the axis of rotation
• CPC Class Codes: F16D 43/284 controlled by angular speed
• CPC Class Codes: F16D 67/04 fluid actuated

Abstract

A clutch mechanism is provided for a cooling fan of a size capable of fitting into the limited envelope available in an over-the-road diesel tractor. A compact housing has a belt drive input and an output connected to the fan hub. The housing includes a pressure chamber in fluid communication with a pressurized air supply and a controllable valve in the air supply line for regulating the pressure in the pressure chamber when the clutch must be operated. The air pressure actuates an internal piston to translate the clutch in a continuously variable manner between engaged and disengaged conditions.

A small envelope clutch, having an outer diameter less than about 9.8 inches in diameter within the fan hub and less than about 6 inches under the belts and 7.3 inches overall so the housing may be positioned between the radiator and the engine, is capable of generating 150 foot-pounds of torque, running a 55 horsepower fan at 2100 rpm, and dissipating 10 horsepower of heat while in the slip mode. The clutch also has at least 130 inches in clutch area.

Fan speed is controlled utilizing a closed loop control system. The control system is capable of monitoring engine conditions and controlling fluid pressure actuating the clutch assembly to control the fan speed in response to the engine conditions.

Claims

1. A clutch assembly for a cooling fan in a vehicle, the clutch assembly comprising, in combination:

a compact housing having a drive belt input and a drive hub output for driving the fan;

a continuously variable clutch within the housing capable of operating between a fully engaged position in which the input and hub are rotated at the same speed, a declutched position in which the drive hub is stationary, and continuously variable positions therebetween in which the drive hub is rotated at continuously variable speeds the clutch including a plurality of juxtaposed driving and driven plates operated by a pressure plate;

the housing having a pressure chamber in fluid communication with a pressurized air supply;

a piston in the housing operatively connected to a translatable clutch hub which carries the pressure plate, the piston being arranged to exert a force on the clutch hub in proportion to a controlled level of air pressure in the pressure chamber, thereby to vary the force exerted by the pressure plate on the driving and driven plates so as to regulate the output speed of the fan hub at a continuously variably controllable rate as a function of the applied pressure between the fully engaged and declutched positions; and

an electrically operable valve disposed between the pressure chamber and air supply for controlling air pressure from the air supply to the pressure chamber and thereby controlling the pressure within the chamber and the position of the clutch between the fully engaged and declutched positions.

2. The clutch assembly of claim 1 wherein the housing further comprises a brake operatively configured to be engaged in the declutched position and physically lock the drive hub output when the clutch is in the declutched position.

3. The clutch assembly of claim 2 wherein the brake comprises a first inclined member non-rotationally mounted in the housing, and a cooperating second inclined member which is mounted so as to rotate at the same speed as the drive hub.

4. The clutch assembly of claim 3 comprising a spring means for biasing the second inclined member towards locking engagement with the first inclined member as the clutch is positioned from the fully engaged position towards the declutched position.

5. The clutch assembly of claim 1 further comprising a spring means for biasing the clutch towards its declutched position, and wherein the piston acts to controllably overcome the spring means for permitting the clutch to move toward the fully engaged position.

6. The clutch assembly of claim 1 further comprises electrical processor means for accepting a plurality of sensed signals from the vehicle and producing a single output signal for controlling the electrically operable valve and thereby the condition of the clutch.

7. The clutch assembly of claim 1 wherein the driving and driven plates are disposed between the pressure plate and a wall of the housing, and are positioned between the fully engaged and declutched positions in response to the pressure from the pressure plate exerted by the clutch hub.

8. The clutch assembly of claim 1 wherein the housing has means for coupling the housing to the drive hub independent of the position of the clutch so that the drive hub rotates at the same speed as the drive belt input.

9. The clutch assembly of claim 8 wherein the coupling means comprises cooperating bores in the a housing bore and a drive hub bore and a bolt for engaging both bores and thereby connecting the drive hub and housing together.

10. The clutch assembly of claim 1 further comprising a speed sensor mounted in the housing and adapted to produce a signal representative of the rotational speed of the drive hub, and circuit means connected to the speed sensor for controlling the electrically operable valve to determine the rotational speed of the drive hub.

11. The clutch assembly of claim 10 comprising a processor connected to sense a plurality of engine conditions, the processor having a fan speed sensor input connected to the speed sensor, the processor having an output for controlling the electrically operable valve.

12. The clutch assembly of claim 11 wherein the engine conditions which the processor is connected to sense are selected from the group consisting of engine coolant temperature, charge air temperature, freon pressure or temperature, and hydraulic temperature.

13. The clutch assembly of claim 12 further including a fan drive oil temperature input for signaling a condition of overheating in the housing, and the processor including means for locking the clutch in the fully engaged position when overheating is detected.

14. A clutch assembly for a cooling fan in a vehicle, the clutch assembly comprising in combination:

a compact housing having a drive belt input and a drive hub for driving the fan;

a continuously variable clutch within the housing capable of operating between a fully engaged position in which the input and hub are rotated at the same speed, a declutched position in which the drive hub is stationary, and continuously variable positions therebetween in which the drive hub is rotated at continuously variable speeds, the clutch including a plurality of juxtaposed driving and driven plates operated by a pressure plate;

the housing having a pressure chamber in fluid communication with a pressurized air supply;

a clutch hub in the housing carrying the pressure plate for exerting a controllable force on the driving and driven plates for releasing and engaging the clutch between the fully engaged and declutched positions in response to the pressure in the chamber, wherein the clutch hub is slidably mounted for movement along an output shaft which drives the drive hub and has a splined connection thereto so as to transmit torque from the driven plates to the drive hub, the clutch hub being arranged with respect to the splined connection and pressure plate such that translation along the splined connection occurs when the clutch is substantially declutched and variation of the hub speed is achieved with substantially no translation along the splined connection by modulating the pressure applied by the pressure plate to the driving and driven plates, such that controllable pressure applied to the pressure chamber is effective to continuously vary the speed of the drive hub primarily by modulating the pressure applied by the pressure plate to the driving and driven plates.

15. The assembly of claim 14 comprising an electrically operable valve disposed between the pressure chamber and air supply for controlling air flow from the air supply to the pressure chamber and thereby controlling the pressure within the chamber and on the clutch hub, thereby controlling the position of the clutch between the fully engaged and declutched positions.

16. The assembly of claim 14 wherein the driving and driven plates are disposed between the clutch hub and a wall of the housing and are positioned between the fully engaged and declutched positions in response to the pressure from the clutch hub.

17. The assembly of claim 14 comprising a spring means biasing the clutch hub in opposition to the pressure in the chamber.

18. The assembly of claim 17 wherein the spring means biases the clutch hub towards the declutched position in response to decreases in the pressure in the chamber.

19. A clutch assembly for a cooling fan in a vehicle, the clutch assembly comprising, in combination:

a compact housing having a drive belt input and a drive hub output for driving the fan;

a continuously variable clutch within the housing capable of moving between a fully engaged position in which the input and hub are rotated at the same speed, a declutched position in which the drive hub is stationary, and continuously variable positions therebetween in which the drive hub is rotated at continuously variable speeds;

the housing having a pressure chamber in fluid communication with a pressurized air supply;

a piston in the housing operatively connected to the clutch for releasing and engaging the continuously variable clutch between the fully engaged and declutched positions in response to the pressure in the chamber;

an electrically operable valve disposed between the pressure chamber and air supply for controlling air pressure from the air supply to the pressure chamber and thereby controlling the pressure within the chamber and the position of the clutch between the fully engaged and declutched positions; and

a speed sensor mounted in the housing and adapted to produce a signal representative of the rotational speed of the drive hub, and circuit means connected to the speed sensor for controlling the electrically operable valve to determine the rotational speed of the drive hub.

20. The clutch assembly of claim 19 comprising a processor connected to sense a plurality of engine conditions, the processor having a fan speed sensor input connected to the speed sensor, the processor having an output for controlling the electrically operable valve.

21. The clutch assembly of claim 20 wherein the engine conditions which the processor is connected to sense are selected from the group consisting of engine coolant temperature, charge air temperature, freon pressure or temperature, and hydraulic temperature.

22. The clutch assembly of claim 21 further including a fan drive oil temperature input for signaling a condition of overheating in the housing, and the processor including means for locking the clutch in the fully engaged position when overheating is detected.