Abstract: A clutch unit (47) comprises a wet friction clutch for controllable transmission of a torque from an input element (41) to an output element (45), housing that contains the friction clutch and oil for cooling the friction clutch, and an actuator (51) for actuating the friction clutch. The actuator is attached to the housing in a thermally conductive way and has a temperature sensor (108) for sensing a temperature of the actuator. In order to computationally determine the oil temperature (TÖl) in the clutch unit (47), a thermal input power to the clutch unit is determined as a function of at least a speed of the input element and/or of the output element. The difference between the thermal input power and the thermal output power is determined, and the oil temperature is determined as a function of the difference that was determined.

Abstract: Accordingly, a control system for controlling a viscous clutch of a fan is provided. The control system includes a delta speed module that determines one of an over speed condition, an under speed condition, and a steady state condition based on a desired fan speed and an actual fan speed. A mode module determines a mode of the clutch based on the one of the over-speed condition, the under-speed condition, and the steady state condition, wherein the mode is one of a pump in mode, a pump out mode, and a closed loop mode. A valve control module that controls an operational state of the clutch valve based on the mode.

Abstract: A viscous fluid coupling device includes a drive shaft, a housing rotatably supported by the drive shaft, a partition wall dividing an interior space of the housing into an operation chamber and a storage chamber having a circular arc portion, a rotor accommodated in the operation chamber and fixed to the drive shaft, a supply passage for supplying operating fluid from the storage chamber to the operation chamber, a return passage for returning the operating fluid in the operation chamber to the storage chamber, and a first valve disposed in the supply passage and the return passage respectively. The first valve is closed when the drive shaft rotates at a speed lower than a predetermined rotation speed and opened when the drive shaft rotates at the predetermined rotation speed. The viscous coupling device further includes an opening of the supply passage and a second valve for opening and closing the opening.

Abstract: A multiple coupling fan drive provides power to a fan in a cooling system. An input shaft drives a constant viscous coupling and a variable viscous coupling, both of which are operative to drive the fan.

Abstract: An electronically-controlled viscous fan drive having a one-piece accumulator and reservoir located on the top side of the clutch. The accumulator also has a low pressure and high pressure fill hole for allowing movement of viscous fluid from the reservoir to a anti-bleedback chamber and into the operating and working chamber of the coupling during normal operation. A radially balance valve disk having a step up feature coupled to a spring and an actuator electronically controls movement of viscous fluid from the reservoir to the anti-bleedback chamber through the fill holes by energizing or deenergizing the spring based on engine operating conditions. The valve disk may be a one-piece or two-piece design. The accumulator is designed to prevent morning sickness associated with the flow of viscous fluid from the reservoir to the operating chamber during engine off situations.

Abstract: A method is disclosed for controlling the slip power of a viscous fluid fan drive clutch, especially of a cooling fan drive for an automotive vehicle. Data is prepared correlating slip power generation with clutch input and output speeds for the clutch and fan design. A maximum slip power for the operation of the cooling fan is specified by considering, for one, fan drive durability requirements. During operation of a computer based, fan speed control module, a desired fan drive speed is continually determined for the cooling requirements of the vehicle and the desired fan speed is compared, and adjusted, if appropriate, to avoid excessive slip power.

Abstract: The present invention provides a method and apparatus for controlling the pressure of an actuating fluid flowing through an inching clutch. The invention includes the steps of determining an actual pressure of the actuating fluid, establishing an inching pressure threshold, comparing the actual pressure with the threshold, and controlling the actual pressure in response to the comparison. In one embodiment, the pressure is controlled using a first control algorithm in response to the fluid pressure being less than an inching threshold, and using a second control algorithm in response to the pressure being greater than or equal to the inching threshold.