A fluid friction clutch, especially for driving the cooling fan of an internal combustion engine. The rotating clutch housing has a separating wall defining a fluid reservoir chamber and a drive chamber and the separating wall has a passage which is opened and closed by a valve. The valve is actuated by an electromagnet disposed substantially coaxially with the clutch. A permanent magnet is attached to the valve assembly coaxially with the electromagnet and of opposite polarity to the magnetic field polarity which occurs when the electromagnet is energized. Upon energization, the opposing magnetic fields repel the two magnets and cause the valve to close, thereby disengaging the clutch. When the electromagnetic is deenergized, a spring reopens the valve and permits full engagement of the clutch.
An electronically controlled hydraulic clutch includes a driveshaft and drive disc which is mounted thereon and rotates in a working chamber of a housing which is rotatably mounted on the driveshaft. The housing has in addition a reservoir chamber which is divided off from the working chamber by a dividing wall and which is connected in terms of flow to the working chamber via a valve opening and a return channel. The valve opening is controlled via a valve lever which is actuated by an electromagnet which is mounted in a fixed manner so as to be capable of rotating on the housing, and the electromagnet is arranged within the reservoir chamber.
Disclosed is a fluid friction clutch assembly, comprising a drive shaft; a primary disk mounted for rotation on the drive shaft; a driven clutch housing surrounding the primary disk and being rotatably supported with respect to the drive shaft, the clutch housing containing a partition therein defining a work chamber and a reservoir separated by the partition, wherein the partition includes in its radially outer area at least one overflow opening closeable by means of a valve lever comprised of a magnetic material and a return flow orifice associated with pump means for pumping a viscous torque-transmitting medium from the work chamber to the reservoir; a pulley member mounted on the drive shaft for driving the shaft and means, associated with the pulley member, for selectively magnetically actuating the valve lever, in order to selectively open and close the overflow opening.
An actuator which, by a movement of a component which is generated by means of an electric current, can effect control of another component in a mechanical environment having rotating parts which are housed in a very small space. A rotating element, for example a clutch shaft (1; 21), is hollow, and an electromagnetic coil arrangement (7; 24) is housed in this cavity in such a way that the excitation of the coil is converted into a mechanical displacement of a component arranged outside the clutch shaft, for example of a sleeve sliding axially on the clutch shaft. For this purpose, parts of the clutch shaft are made ferromagnetic and are integrated in the magnetic loop of the coil (7; 24). The actuator according to the invention can be used, for example, in a viscous clutch for controlling the throughput of shear medium.
A fluid coupling device is provided of the type including an input coupling (11) and an output coupling assembly (13) including a case cover member (17) including a chimney portion (39) and chimney extension (81). The coupling includes a valve plate (31) defining a fluid port (45), and operation of the coupling is controlled in response to the rotational position of the valve arm (43), by means of a valve shaft (41). The position of the valve shaft (41) is controlled, in response to an electrical input signal by means of an actuator assembly (61), which includes an annular steel housing member (63). The housing member is stationary, and is mounted relative to the chimney extension (81) by means of a set of ball bearings (77) which comprise the only bearing support between the actuator assembly (61) and the rotating coupling. As a result of this design, there is no high speed interface between the rotating coupling and the stationary actuator assembly to result in excessive wear, heat generation, and degradation of performance.
A viscous fan clutch (10) is typically employed in a fan drive mechanism within a truck or automobile. A shaft (12) driven by the engine, rotates a clutch member (24) within the fan drive. The clutch member is arranged for fluid engagement with a body member (42) for the transmission of torque thereto when the fluid is disposed in an operating chamber (70) defined by complimentary shear surfaces (30 and 56) in the clutch and body members. During relative rotation between the two members, fluid is pumped from the operating chamber to a storage chamber (76). Fluid is returned to the operating chamber via bleed ports (94) which are selectively restricted by an electromagnetically controlled valve (88). A control system (110) senses vehicle coolant temperature and actuates the valve as a function thereof.
