Viscous fluid clutch

Claim 2

A viscous clutch comprising first and second relatively rotatable drive means, said first drive means having an annular operating chamber and a reservoir chamber, fluid shear drive means on said first and second drive means located in said operating chamber operable with a fluid medium to provide a shear-type fluid drive between said first and second drive means, said operating chamber having outlet opening means at an outer portion thereof and inlet opening means at an inner portion thereof, pump means on one of said drive means to pump said fluid medium from said operating chamber out of said outlet opening means into said reservoir chamber, and speed-responsive valve means operatively connected to said inlet opening means for permitting the flow of said fluid medium therethrough from said reservoir chamber to said operating chamber at an intermediate range of speeds of said second drive means and for preventing flow therethrough at all lower and higher speeds of said second drive means.

Claim 3

A viscous clutch comprising first and second relatively rotatable drive members, said first drive member including a first wall, a second wall and a divider wall sealed between said first and second walls providing a working chamber between said divider and second walls and a second chamber between said first and divider walls, said second drive member being rotatably mounted in said working chamber, fluid shear drive means on said first and second drive members in said working chamber operable with a fluid medium to provide a shear-type fluid drive therebetween, first opening means in said divider wall for providing communication from said working chamber to said second chamber, pump means on one of said drive members for causing said fluid medium to flow from said working chamber through said first opening means to said second chamber, second opening means formed in said divider wall for communicating said fluid medium from said second chamber to said working chamber, centrifugally responsive valve means slidably mounted in said second chamber for controlling the flow of said fluid medium from said second chamber through said second opening means into said working chamber by opening said second opening means only during a first predetermined intermediate range of speeds of said second drive member so as to maintain the speed of said first drive member at substantially a second predetermined speed range regardless of any change in speed of said second drive member above the upper limit of said first predetermined speed range.

Claim 4

A viscous clutch comprising first and second relatively rotatable drive members, said first drive member including a first wall, a second wall and a divider wall sealed between said first and second walls providing a working chamber between said divider and second walls and a second chamber between said first and divider walls, said second drive member being rotatably mounted in said working chamber, fluid shear drive means on said first and second drive members in said working chamber operable with a fluid medium to provide a shear-type fluid drive therebetween, first opening means in said divider wall for providing communication from said working chamber to said second chamber, pump means on one of said drive members for causing said fluid medium to flow from said working chamber through said first opening means to said second chamber, second opening means formed in said divider wall for communicating said fluid medium from said second chamber to said working chamber, centrifugally responsive valve means slidably mounted in said second chamber for controlling the flow of said fluid medium from said second chamber through said second opening means into said working chamber by opening said second opening means only during a first predetermined intermediate range of speeds of said second drive member so as to maintain the speed of said first drive member at substantially a second predetermined speed range regardless of any change in speed of said second drive member above the upper limit of said first predetermined speed range.

Claim 5

A viscous fluid clutch comprising an input shaft, a clutch plate secured to said shaft, a fluid clutch housing rotatably mounted on said input shaft, a cover member sealed to said housing, a divider wall secured for rotation with said cover member and said housing and mounted between said cover member and said clutch plate so as to form an annular reservoir with said cover member and a working chamber with said housing, an outlet port formed in said divider wall between said working chamber and said annular reservoir, pump means operatively connected to said divider wall for pumping a fluid medium from said working chamber through said outlet port to said annular reservoir, an inlet port formed in said divider wall for at times communicating said fluid medium from said annular reservoir to said working chamber, speed-responsive valve means operatively connected to said divider wall for controlling the flow of said fluid medium through said inlet port from said annular reservoir to said working chamber, and resilient means operatively connected to said valve means for preventing said valve means from opening said inlet port below a first predetermined clutch housing speed and for reclosing said inlet port above a second higher predetermined clutch housing speed.

Claim 6

A viscous fluid clutch comprising an input shaft, a clutch plate secured to said shaft, a fluid clutch housing rotatably mounted on said input shaft, a cover member sealed to said housing, a divider wall secured for rotation with said cover member and said housing and mounted between said cover member and said clutch plate so as to form an annular reservoir with said cover member and a working chamber with said housing, an outlet port formed in said divider wall between said working chamber and said annular reservoir, pump means operatively connected to said divider wall for pumping a fluid medium from said working chamber through said outlet port to said annular reservoir, an inlet port formed in said divider wall for at times communicating said fluid medium from said annular reservoir to said working chamber, speed-responsive valve means operatively connected to said divider wall for controlling the flow of said fluid medium through said inlet port from said annular reservoir to said working chamber, and resilient means operatively connected to said valve means for preventing said valve means from opening said inlet port below a first predetermined clutch housing speed and for reclosing said inlet port above a second higher predetermined clutch housing speed.

Claim 7

A viscous fluid clutch comprising first and second relatively rotatable drivE members, said first drive member including front and rear walls and defining a fluid cavity therebetween, a divider wall sealed between said front and rear walls in said fluid cavity and dividing said fluid cavity into first and second chambers, said second drive member being rotatable in said first chamber, said second drive member and said rear wall having opposed spaced parallel surfaces defining a fluid shear space therebetween and cooperable with a fluid medium in said shear space to provide a shear-type fluid drive therebetween, a first opening formed in said divider wall for providing communication between said first chamber and said second chamber, a dam element formed on said divider wall in said first chamber adjacent said first opening for causing said fluid medium to flow through said first opening for varying the volume of said fluid medium in said shear space to vary the torque transmitted between said first and second drive members, a second opening formed in said divider wall for at times communicating said fluid medium from said second chamber to said first chamber, speed-responsive valve means for controlling the opening and closing of said second opening, first resilient means for preventing said valve means from opening said second opening below a first predetermined speed of said first drive member, and second resilient means for preventing said valve means from closing said second opening below a second higher predetermined speed of said first drive member.

Claim 8

A viscous fluid clutch comprising first and second relatively rotatable drivE members, said first drive member including front and rear walls and defining a fluid cavity therebetween, a divider wall sealed between said front and rear walls in said fluid cavity and dividing said fluid cavity into first and second chambers, said second drive member being rotatable in said first chamber, said second drive member and said rear wall having opposed spaced parallel surfaces defining a fluid shear space therebetween and cooperable with a fluid medium in said shear space to provide a shear-type fluid drive therebetween, a first opening formed in said divider wall for providing communication between said first chamber and said second chamber, a dam element formed on said divider wall in said first chamber adjacent said first opening for causing said fluid medium to flow through said first opening for varying the volume of said fluid medium in said shear space to vary the torque transmitted between said first and second drive members, a second opening formed in said divider wall for at times communicating said fluid medium from said second chamber to said first chamber, speed-responsive valve means for controlling the opening and closing of said second opening, first resilient means for preventing said valve means from opening said second opening below a first predetermined speed of said first drive member, and second resilient means for preventing said valve means from closing said second opening below a second higher predetermined speed of said first drive member.

Claim 9

A viscous clutch comprising first and second relatively rotatable drive members, said first drive member including a first wall, a second wall and a divider wall sealed between said first and second walls providing a working chamber between said divider and second walls and a reservoir chamber between said first and divider walls, said second drive member being rotatably mounted in said working chamber, fluid shear drive means on said first and second drive members in said working chamber operable with a fluid medium to provide a shear-type fluid drive therebetween, an outlet opening in said divider wall for providing communication from said working chamber to said reservoir chamber, pump means on one of said drive members for causing said fluid medium to flow from said working chamber through said outlet opening to said reservoir chamber, an inlet opening formed in said divider wall for communicating said fluid medium from said reservoir chamber to said working chamber, shaft means connected between said first and divider walls, centrifugally responsive valve means slidably mounted in said reservoir chamber with opening means around said shaft means, first spring means mounted in an opening formed in said valve means and having one end thereof movable at all times with said valve means and the other end thereof abutting against said shaft means, second spring means surrounding said first spring means in said opening and having one end thereof movable at all times with said valve means and the other end thereof movable at times with a shoulder formed on said valve means and at all other times abutting against said shaft means and caused to leave said shoulder, said first spring means compressing under the action of centrifugal force to permit said valve means to rapidly open said inlet opening at a first predetermined speed of said first drive member at which time said second spring means abuts against said shaft means to prevent said valve means from closing off said inlet opening until a second higher predetermined speed of said first drive member is attained.

Claim 10

A viscous clutch comprising first and second relatively rotatable drive members, said first drive member including a first wall, a second wall and a divider wall sealed between said first and second walls providing a working chamber between said divider and second walls and a reservoir chamber between said first and divider walls, said second drive member being rotatably mounted in said working chamber, fluid shear drive means on said first and second drive members in said working chamber operable with a fluid medium to provide a shear-type fluid drive therebetween, an outlet opening in said divider wall for providing communication from said working chamber to said reservoir chamber, pump means on one of said drive members for causing said fluid medium to flow from said working chamber through said outlet opening to said reservoir chamber, an inlet opening formed in said divider wall for communicating said fluid medium from said reservoir chamber to said working chamber, shaft means connected between said first and divider walls, centrifugally responsive valve means slidably mounted in said reservoir chamber with opening means around said shaft means, first spring means mounted in an opening formed in said valve means and having one end thereof movable at all times with said valve means and the other end thereof abutting against said shaft means, second spring means surrounding said first spring means in said opening and having one end thereof movable at all times with said valve means and the other end thereof movable at times with a shoulder formed on said valve means and at all other times abutting against said shaft means and caused to leave said shoulder, said first spring means compressing under the action of centrifugal force to permit said valve means to rapidly open said inlet opening at a first predetermined speed of said first drive member at which time said second spring means abuts against said shaft means to prevent said valve means from closing off said inlet opening until a second higher predetermined speed of said first drive member is attained.