Gm Global Technolgoy Operations, Inc.

Harvard Industries, Inc.

Mahle Behr USA Inc.

Lawrence C Kennedy

Harvey J Lambert

James O Strader

David Bernard Drennen

Anthony L Smith

Carl A Nilson

Ronald G Huth

David M Hudson

Joseph Kowalis

A viscous fluid clutch for use as a clutch for a cooling fan for a vehicle, the clutch includes an input shaft, a rotor assembly, a first housing portion, a second housing portion, a coil assembly, and a brush box. The rotor assembly is coupled to the input shaft. The first housing portion is coupled to the second housing portion and the second housing portion is rotatably disposed on the input shaft. The first and second housing portions define a fluid reservoir for receiving the rotor assembly and a viscous fluid, preferably of the magnetorheological type. The coil assembly is coupled to the first housing portion. The brush box is operably coupled to the coil assembly. When the coil assembly is energized by the brush box, a magnetic field is created that acts upon the magnetorheological fluid to vary the torque transfer of the input shaft to the housing and the fan connected thereto.

Clutch assembly

An improved magnetorheological (MR) fluid fan drive design is disclosed. A critical area in the design of such fan drives is the gap for MR fluid between the rotor ring and the corresponding structure of the stator. The stator member must confine the MR fluid in the gap and the applied magnetic field for the fluid and the field coil close to it. In this disclosure a ferrous alloy stator insert is made as one piece and cast within a larger aluminum alloy stator body. A slot for the rotor ring is cut through stator insert separating it into two pieces that remain supported by the aluminum body. The magnetically permeable insert pieces confine the fluid and the magnetic field at the fluid gap around the rotor, and one of the stator insert pieces supports the field coil next to the gap.

Magnetorheological fluid fan drive design for manufacturability

An internal combustion engine coolant fan assembly including a self contained thermally controlled clutch or externally controlled clutch having a housing and a fan blade assembly which is attached to the housing by a circular hub utilizing an interference fit or threaded connection. Preferably, the housing includes cooling fins, and the blade assembly circular hub is mounted on the outer edges of the cooling fins.

Plastic fan and thermal clutch drive

A clutch includes an input element with an engaged input shaft and clutch plate rotatable in concert. The clutch plate has an annular portion with a clutch plate set of lands and grooves mating with a housing set of lands and grooves to define a shear zone space. A cover is included as part of the housing and engages the body and includes a reservoir. A pump plate is captured between the cover and the body separating out a working chamber generally within the body and includes a pump port. The pump port includes an outer extreme edge that is substantially in line with the outer surface of the clutch plate. A valve port in the pump plate is positioned near the radial outside of the reservoir. A control arm normally closes the valve port and is movable to open the valve port. When the valve port is closed, fluid carried in the working chamber moves radially outward under centrifugal force and is forced through the pump port under operation of a wiper due to relative rotation between the clutch plate and the pump plate so that substantially all of the fluid is pumped out of the working chamber and a high slip speed is established between the housing and the clutch plate. A rotating peripheral accumulator is defined between the depleted surface of the clutch plate and the annular step of the body that accommodates fluid inertia and provides volumetric compensation for fluid pressurization and compression caused by an externally applied torque change.

Low disengage speed fan clutch

A clutch includes an input shaft with a clutch plate engaged with the input shaft to rotate in concert therewith. The clutch plate has an annular disk portion with a clutch plate set of lands and grooves. A housing includes a body supported on the input shaft by a bearing with a body set of lands and grooves mating with the clutch plate set of lands and grooves. A cover is included as part of the housing and engages with the body. A pump plate is captured between the cover and the body separating out a working chamber. The pump plate includes an engage port and a pump-out port positioned further radially outward in the pump plate than the engage port. A control arm normally closes the engage port and is rotatable to open the engage port. A slide-block is carried in a pocket of the cover with a spring biasing the slide-block toward engagement with the control arm. The slide-block locks the control arm against rotation when the clutch is inactive.

Viscous fan clutch with engage port lock

A fan clutch includes a housing and a cover cooperating to contain a viscous fluid. A pump plate divides an interior of the fan clutch into a working chamber and a reservoir. A driven clutch plate, disposed in the working chamber, includes hub and disk portions. A wiper is mounted on the pump plate adjacent a discharge orifice so that a first clearance is provided between the wiper and a front surface of the disk portion. An annular blocking wall is formed on the front surface of the disk portion radially inbound of the wiper. The height of the blocking wall is such that a second clearance formed between the blocking wall and the pump plate is less than or substantially equal to the first clearance, thereby forming a dynamic seal.

Clutch plate with blocking wall for a viscous fluid clutch

A viscous fluid clutch includes a clutch plate rotatably driven by an input shaft. The clutch plate includes a plurality of concentric, annular lands and grooves in a rear face which are mated with complementary lands and grooves of a clutch body to form a shear zone. A plurality of passages are provided in the clutch plate lands and grooves for directing fluid from a reservoir to the shear zone. A first system of arcuate ramps are provided in a front surface of the clutch plate facing a pump plate of the clutch. The arcuate ramps are radially aligned with pump plate orifices and enhance the pump-out of fluid through the orifices. If desired, a second system of circumferential ramps can be provided about the periphery of the clutch plate to enhance the pump-out of fluid.

Ramped clutch plate for a viscous fluid clutch

A viscous fluid clutch having a bimetallic coil includes an insulating retainer. A body of the retainer is mounted between the coil and an outer surface of the clutch housing. A flexible tab on the retainer is placed between a first end of the coil and a slot on the clutch housing to provide an interference fit and eliminate the need for adhesives. The body inhibits the transfer of radiant heat emanating from fluid inside the clutch to the coil. Preferably, the body and tab are integrally formed.

Insulating retainer for a viscous fluid clutch

A viscous fluid fan clutch assembly for a vehicle includes an internally-mounted pump plate for separating a working chamber from a reservoir. A plurality of discharge orifices are provided in the pump plate to permit the return of fluid from a pumping chamber to the reservoir. A fluid discharge channel is provided for each discharge orifice to receive fluid exiting the pumping chamber and to direct the fluid to an inner portion of the reservoir. A check valve is provided at the discharge channel to prevent the flowback of fluid from the reservoir to the discharge channel, particularly when the clutch assembly is not in operation.

Anti-flowback check valve for a viscous fluid clutch

A viscous fluid fan clutch assembly for a vehicle includes an internally-mounted pump plate for separating a working chamber from a reservoir. A plurality of pressure-sensitive fluid check valves are provided in the pump plate to permit only one-way fluid flow from a pumping chamber to the reservoir. Each check valve includes an interior chamber having a pair of angled side walls which terminate at a normally-closed outlet. When a predetermined fluid pressure is achieved in the pumping chamber, the side walls are forced apart to open the outlet. The closing of the outlet is not dependent upon fluid pressure in the reservoir.

Pressure-responsive fluid check valve and method for viscous fluid clutch

A fan clutch assembly for a vehicle includes a flexible, ferromagnetic valve plate for controlling fluid flow through a pump plate into a shear zone. When an electromagnetic coil is energized, the resulting flux deflects the valve plate away from the pump plate to open fluid gates in the pump plate. When the coil is de-energized, the valve plate returns to its original engagement position against the pump plate to close the fluid gates.

Electromagnetically actuated valve plate for a viscous fluid fan clutch

A viscous fluid fan clutch assembly for a vehicle includes an internally-mounted pump plate for separating a working chamber from a reservoir. At least one fluid gate is provided in the pump plate to permit fluid flow from the reservoir to the working chamber. Only one discharge orifice is provided in the pump plate for permitting the return of fluid from the working chamber to the reservoir. Air vents are provided inbound of the discharge orifice to permit the passage of air between the reservoir and the working chamber. A check valve is mounted at the vent means to provide selective control of air through the air vents.

Internal airflow check valve and method for a viscous fluid clutch

A preload control arm for controlling fluid flow through a viscous fluid clutch includes a rotatable control shaft mounted in the clutch. The control arm is secured to the control shaft so that flexible end portions of the control arm cover pump plate orifices in the clutch. A spring secured to the control shaft provides a force adajcent the end portions opposite the pump plate orifices to maintain the seal when the control arm is in the closed position.

Preloaded control arm for a viscous fluid clutch

A fan clutch assembly for a vehicle includes a rotatable pump plate for separating a collecting chamber and a pumping chamber from a reservoir. The pump plate includes at least one wiper integrally formed with the pump plate and projecting from a pump plate surface into the pumping chamber. An aperture oriented in the direction of oncoming fluid in the pumping chamber is provided through the wiper to form an orifice for fluid to pass from the pumping chamber to the reservoir. A damming surface oriented toward the orifice is provided on the wiper for creating a pressure rise and enhancing the pump-out of fluid from the pumping chamber.

Integrally formed wiper and orifice for a pump plate of a viscous fluid

A floating wiper assembly mounted on a pump plate of a viscous fluid clutch includes a spring secured at its first end to a pump plate. A wiper formed from a low-friction material is secured to a second end of the spring and received in an opening in the pump plate. During assembly of the clutch, the wiper is urged by the spring into the pumping chamber and accommodates variances in machining and assembly variances. The wiper projects into a pumping chamber to create a fluid pressure rise to enhance the pump-out through an orifice of fluid in the pumping chamber to the reservoir.

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Kettering, OH, United States of America

Lawrence C Kennedy