Magnetically actuated viscous fluid coupling

Abstract

A viscous fluid clutch employing a magnetic field selectively actuatable by a heat sensing device to operate a valve arm to seal an inlet passage fluidly communicating an operating chamber with a storage chamber. The clutch includes a clutch and a housing member rotatably disposed relative to one another. Each member has a shear surface. The surfaces define therebetween the operating chamber. The storage chamber is located in the housing member and is in fluid communication with the operating chamber via a discharge passage and the inlet passage. Pump means in the operating chamber displace fluid through the discharge passage from the operating chamber to the storage chamber. The inlet passage directs fluid from the storage to the operating chamber. A movable valve arm selectively seals the inlet passage. The valve arm is moved via a solenoid action in response to actuation of the magnetic field. Fluid is disposed within the clutch and is used, when located in the operating chamber, to rotate the housing members in response to rotation of the clutch member. When the fluid is displaced from the operating to the storage chamber, rotation of the housing member is reduced.

What is claimed is: 
     
       1. A viscous fluid clutch comprising a shaft made of magnetic material;   a first member secured to said shaft;   a second member rotatably disposed on said shaft relative to said first member;   shear surfaces disposed on said first and second members and forming an operating chamber therebetween;   a fluid storage chamber adjacent said operating chamber;   means for selectively inducing a magnetic field in said shaft;   valve means effecting selective communication between said storage chamber and said operating chamber and including a valve member, including an armature made of a magnetic material and located adjacent said shaft, movable in response to the induction of said magnetic field in said shaft from a first position to a second position, one of said positions providing communication between said storage chamber and said operating chamber and the other of said positions blocking such communication;   fluid means disposed within said storage chamber and being selectively displaced into said operating chamber when said valve member is in said one position to provide in said operating chamber a medium to transmit rotational movement from one of said members to the other of said members; and   pump means in said operating chamber to displace said fluid means from said operating chamber to said storage chamber.   
     
     
       2. A clutch according to claim 1 wherein said members are radially disposed and rotatable about a common axis; said chambers are axially disposed along said axis and are separated by a radially extending valve plate, said valve plate including an opening radially disposed from said axis of rotation;   said valve member is mounted for axial movement in said valve plate and includes a radially disposed valve arm that is movable from a position sealing said opening when said valve member is in said one position to a position spaced from said opening when said valve member is in said other position.   
     
     
       3. A clutch according to claim 2 further comprising means axially biasing said valve member away from said valve plate. 
     
     
       4. A clutch according to claim 2 wherein said valve plate and said members are made of a non-magnetic material. 
     
     
       5. A clutch according to claim 4 further comprising means biasing said armature axially away from said shaft; and means limiting the axial distance said armature is biased away from said shaft to a value which allows attraction of said armature to said shaft by said magnetic field.   
     
     
       6. A clutch according to claim 5 wherein said valve member is in one of said positions when said armature is spaced from said shaft and is in the other of said positions when said armature is drawn toward said shaft by said magnetic field. 
     
     
       7. A viscous fluid clutch according to claim 1 wherein said means for inducing a magnetic field includes a coil .[.spring.]. encircling said shaft. 
     
     
       8. A viscous fluid clutch comprising: a shaft rotatable about an axis and made of a magnetic material;   a first radially disposed member secured to said shaft and made of a nonmagnetic material;   a second radially disposed member mounted for rotation on said shaft and made of a nonmagnetic material;   shear surfaces disposed on said first and second members and forming an operating chamber therebetween;   a fluid storage chamber axially spaced from said operating chamber and separated therefrom by a radially extending valve plate, said valve plate including an opening radially disposed from said axis;   means positioned proximate said shaft for selectively inducing a magnetic field in said shaft;   valve means effecting selective communication between said storage chamber and said operating chamber and including a valve member mounted for axial movement in said valve plate, said valve member including a radially disposed valve arm having an armature that is located adjacent said shaft and is made of a magnetic material, said valve arm being movable with said valve member from a first position sealing said radially disposed opening to a second position spaced from said radially disposed opening, said valve member being movable in response to induction of said magnetic field in said shaft from said first position to said second position;   fluid means disposed within said storage chamber and being selectively displaced into said operating chamber when said valve member is in said second position to provide in said operating chamber a medium to transmit rotational movement from one of said members to the other of said members; and   pump means in said operating chamber to displace said fluid means from said operating chamber to said storage chamber.   
     
     
       9. A viscous fluid clutch according to claim 8 wherein said means for inducing a magnetic field includes a coil encircling said shaft. 
     
     
       10. A viscous fluid clutch according to claim 8 further comprising means biasing said armature axially away from said valve plate. 
     
     
       11. A viscous fluid clutch according to claim 10 wherein said armature is concentric with said axis. 
     
     
       12. A viscous fluid clutch according to claim 8 wherein said valve plate includes an opening concentric with said axis and said armature is slidably positioned within said concentric opening. 
     
     
       13. A viscous fluid clutch comprising: a shaft rotatable about an axis and made of a magnetic material;   a generally radially extending clutch member secured to said shaft for rotation therewith;   a generally radially extending housing member encircling said clutch member;   bearing means supporting said housing member on said shaft for rotation relative to said shaft;   shear surfaces disposed on said members;   a valve plate secured to said housing member and together with said housing member defining an operating chamber surrounding said clutch member;   a cover plate secured to said housing member and together with said valve plate defining a fluid storage chamber; a hole concentric with said axis in said valve plate; an armature located within said hole and axially movable therein, said armature having a position that is adjacent said shaft and is made of a magnetic material;   another hole located in said valve plate and disposed radially from said axis;   a valve arm secured to said armature for axial movement therewith and having an outer portion aligned with said other hole and being of a size to cover said other hole, said armature and, accordingly, said valve arm having a first position in which said outer portion covers said other hole and a second position in which said outer portion is spaced from said other hole, said armature being spaced from said shaft in at least one of said positions; means biasing said armature axially relative to said valve plate toward one of said positions;   fluid disposed within said fluid storage chamber and being selectively displaced into said operating chamber through said other hole when said armature is in said second position to provide in said operating chamber a medium to transmit rotational movement from said clutch member to said housing member;   pump means in said operating chamber to displace said fluid from said operating chamber to said fluid storage chamber; and   electrical coil means encircling said shaft for selectively inducing a magnetic field in said shaft to force said armature toward said other position.   
     
     
       14. A viscous fluid clutch according to claim 13 wherein said valve plate and said members are made of a nonmagnetic material. 
     
     
       15. A viscous fluid clutch according to claim 14 wherein said biasing means is a coil spring having one end contacting said valve plate and the other end contacting said valve arm. 
     
     
       16. A viscous fluid clutch according to claim 15 wherein said armature includes an enlarged shoulder portion encircling said concentric hole, said shoulder portion being in contact with said valve plate when said armature is in one of said positions. 
     
     
       17. A viscous fluid clutch according to claim 15 wherein said valve arm is located within said storage chamber. 
     
     
       18. A viscous fluid clutch comprising: a shaft rotatable about an axis and made of a magnetic material;   a generally radially extending clutch member secured to said shaft for rotation therewith and made of a nonmagnetic material;   a generally radially extending housing member encircling said clutch member and made of a nonmagnetic material; bearing means supporting said housing member on said shaft for rotation relative to said shaft;   shear surfaces disposed on said members;   a valve plate secured to said housing member and together with said housing member defining an operating chamber surrounding said clutch member, said valve plate being made of a nonmagnetic material;   a cover plate secured to said housing member and together with said valve plate defining a fluid storage chamber; a hole concentric with said axis in said valve plate; an armature located within said hole and axially movable therein, said armature having a shoulder portion that is adjacent said shaft and is made of a magnetic material, said shoulder portion being located in said operating chamber and being of a size to cover said concentric hole; another hole located in said valve plate and disposed radially from said axis;   a valve arm within said storage chamber secured to said armature for axial movement therewith and having an outer portion aligned with said other hole and being of a size to cover said other hole, said armature and, accordingly, said valve arm having a first position in which said outer portion covers said other hole and a second position in which said outer portion is spaced from said other hole and said shoulder portion contacts said valve plate and covers said concentric hole, said armature being spaced from said shaft in both of said positions;   means biasing said armature axially relative to said valve plate toward said second position;   fluid disposed within said fluid storage chamber and being selectively displaced into said operating chamber through said other hole when said armature is in said second position to provide in said operating chamber a medium to transmit rotational movement from said clutch member to said housing member;   pump means in said operating chamber to displace said fluid from said operating chamber to said fluid storage chamber; and   electrical coil means encircling said shaft for selectively inducing a magnetic field in said shaft to force said armature toward said first position. .Iadd. 19. A viscous fluid clutch comprising:   a first member rotatable about an axis;   a second member rotatably disposed on said axis relative to said first member;   shear surfaces disposed on said first and second members and forming an operating chamber therebetween;   a fluid storage chamber adjacent said operating chamber;   a shaft made of a magnetic material and mounted on one of said members for rotation about said axis;   means for selectively inducing a magnetic field in said shaft;   valve means effecting selective communication between said storage chamber and said operating chamber and including a valve member, including an armature made of a magnetic material and located adjacent said shaft, movable in response to the induction of said magnetic field in said shaft from a first position to a second position, one of said positions providing communication between said storage chamber and said operating chamber and the other of said positions blocking such communication;   fluid means disposed within said storage chamber and being selectively displaced into said operating chamber when said valve member is in said one position to provide in said operating chamber a medium to transmit rotational movement from one of said members to the other of said members; and   pump means in said operating chamber to displace said fluid means from said operating chamber to said storage chamber. .Iaddend. .Iadd. 20. A viscous fluid clutch comprising:   a generally radially extending clutch member mounted for rotation about an axis;   a generally radially extending housing member encircling said clutch member;   bearing means supporting said housing member for rotation relative to said clutch member about said axis;   shear surfaces disposed on said members;   a valve plate secured to said housing member and together with said housing member defining an operating chamber surrounding said clutch member;   a cover plate secured to said housing member and together with said valve plate defining a fluid storage chamber;   a shaft rotatable about said axis, mounted on one of said members, and made of a magnetic material;   a hole concentric with said axis in said valve plate;   an armature located within said hole and axially movable therein, said armature having a position that is adjacent said shaft and is made of a magnetic material;   another hole located in said valve plate and disposed radially from said axis;   a valve arm secured to said armature for axial movement therewith and having an outer portion aligned with said other hole and being of a size to cover said other hole, said armature and, accordingly, said valve arm having a first position in which said outer portion covers said other hole and a second portion in which said outer portion is spaced from said other hole, said armature being spaced from said shaft in at least one of said positions;   means biasing said armature axially relative to said valve plate toward one of said positions;   fluid disposed within said fluid storage chamber and being selectively displaced into said operating chamber through said other hole when said armature is in said second position to provide in said operating chamber a medium to transmit rotational movement from said clutch member to said housing member;   pump means in said operating chamber to displace said fluid from said operating chamber to said fluid storage chamber; and   electrical coil means encircling said shaft for selectively inducing a magnetic field in said shaft to force said armature toward said other position. .Iaddend..Iadd. 21. A viscous fluid clutch according to claim 20 wherein said valve plate and said members are made of a nonmagnetic material. .Iaddend..Iadd. 22. A viscous fluid clutch according to claim 21 wherein said biasing means is a coil spring having one end contacting said valve plate and the other end contacting said valve arm. .Iaddend..Iadd. 23. A viscous fluid clutch according to claim 22 wherein said armature includes an enlarged shoulder portion encircling said concentric hole, said shoulder portion being in contact with said valve plate when said armature is in one of said positions. .Iaddend..Iadd. 24. A viscous fluid clutch according to claim 23 wherein said valve arm is located within said storage chamber. .Iaddend. .Iadd. 25. A viscous fluid clutch comprising:   a first member rotatable about an axis;   a second member rotatably disposed on said axis relative to said first member;   shear surfaces disposed on said first and second members and forming an operating chamber therebetween;   a fluid storage chamber adjacent said operating chamber;   a shaft made of a magnetic material and situated on said axis;   a coil for selectively inducing a magnetic field in said shaft;   valve means effecting selective communication between said storage chamber and said operation chamber and including a valve member, including an armature made of a magnetic material, located at least in part adjacent said shaft, and movable in response to the induction of said magnetic field in said shaft from a first position to a second position, one of said positions providing fluid communication between said storage chamber and said operating chamber and the other of said positions blocking such fluid communication;   fluid means disposed within said storage chamber and being selectively displaced into said operating chamber when said valve member is in said one position to provide in said operating chamber a medium to transmit rotational movement from one of said members to the other of said members; and   pump means in said operating chamber to displace said fluid means from said operating chamber to said storage chamber. .Iaddend. .Iadd. 26. A viscous fluid clutch comprising:   a first member rotatable about an axis;   a second member rotatably disposed on said axis relative to said first member;   shear surfaces disposed on said first and second members and forming an operating chamber therebetween;   a fluid storage chamber adjacent said operating chamber;   an annular inductive coil defining a generally cylindrical cavity on said axis;   a member made of a magnetic material, situated on said axis, and located at least in part in said cavity;   electrical means for passing an electric current through said coil to selectively induce a magnetic field in said member made of a magnetic material;   valve means effecting selective communication between said storage chamber and said operating chamber and including a valve member associated with said member made of a magnetic material and movable in response to the induction of said magnetic field from a first position to a second position, one of said positions providing fluid communication between said storage chamber and said operating chamber and the other of said positions blocking such fluid communication;   fluid means disposed within said storage chamber and being selectively displaced into said operating chamber when said valve member is in said one position to provide in said operating chamber a medium to transmit rotational movement from one of said members to the other of said members; and   pump means in said operating chamber to displace said fluid means from said operating chamber to said storage chamber. .Iaddend. .Iadd. 27. A viscous fluid clutch comprising:   a generally radially extending clutch member mounted for rotation about an axis;   a generally radially extending housing member encircling said clutch member;   bearing means supporting said housing member for rotation relative to said clutch member about said axis;   shear surfaces disposed on said members;   a valve plate secured to said housing member and together with said housing member defining an operating chamber surrounding said clutch member;   a cover plate secured to said housing member and together with said valve plate defining a fluid storage chamber;   a member situated on said axis and made of a magnetic material;   a hole located in said valve plate and disposed radially from said axis;   a valve arm having an armature portion that is made of a magnetic material, and axially movable, and that has an outer portion aligned with said hole and being of a size to cover said hole, said valve arm and said armature portion having a first position in which said outer portion covers said hole and a second portion in which said outer portion is spaced from said hole, said armature portion being spaced from said magnetic member in at least one of said positions;   means biasing said valve arm axially relative to said valve plate toward one of said positions;   fluid disposed within said fluid storage chamber and being selectively displaced into said operating chamber through said hole when said valve arm is in said second position to provide in said operating chamber a medium to transmit rotational movement from said clutch member to said housing member;   pump means in said operating chamber to displace said fluid from said operating chamber; and   electrical coil means encircling said magnetic member for selectively inducing a magnetic field in said magnetic member to force said armature portion toward said other position. .Iaddend..Iadd. 28. A viscous fluid clutch according to claim 27 wherein said valve arm is located within said storage chamber. .Iaddend..Iadd. 29. A viscous fluid clutch according to claim 27 further comprising another hole in said valve plate and located proximate said axis to maintain said chambers in said open communication with one another. .Iaddend.