Magnetically actuated viscous fluid coupling

Claim 2

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.

Claim 3

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.

Claim 4

A clutch according to claim 2 further comprising means axially biasing said valve member away from said valve plate.

Claim 5

A clutch according to claim 2 wherein said valve plate and said members are made of a non-magnetic material.

Claim 6

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.

Claim 7

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.

Claim 8

A viscous fluid clutch according to claim 1 wherein said means for inducing a magnetic field includes a coil spring encircling said shaft.

Claim 9

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 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.

Claim 10

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 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.

Claim 11

A viscous fluid clutch according to claim 8 wherein said means for inducing a magnetic field includes a coil encircling said shaft.

Claim 12

A viscous fluid clutch according to claim 8 further comprising means biasing said armature axially away from said valve plate.

Claim 13

A viscous fluid clutch according to claim 10 wherein said armature is concentric with said axis.

Claim 14

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.

Claim 15

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.

Claim 16

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.

Claim 17

A viscous fluid clutch according to claim 13 wherein said valve plate and said members are made of a nonmagnetic material.

Claim 18

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.

Claim 19

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.

Claim 20

A viscous fluid clutch according to claim 15 wherein said valve arm is located within said storage chamber.

Claim 21

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.

Claim 22

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.