Compact ferrofluidic electrically conducting sealed bearing

Claim 2

A sealed rolling element bearing for supporting a shaft of magnetic or nonmagnetic material and for permitting rotation of the shaft relative to a housing, comprising: an inner race attachable to the shaft, said inner race having an annular outer surface; an outer race concentric with said inner race and attachable to the housing, said outer race having an annular inner surface; a plurality of rolling elements located in an annular region between said inner race and said outer race; a pair of shields attached to the outer surface of said inner race and extending outwardly from the outer surface of said inner race toward the inner surface of said outer race on opposite sides of said rolling elements so as to substantially enclose said annular region, each of said shields having a closely-spaced, noncontacting relationship with the inner surface of said outer race thereby defining a gap between each of said shields and the inner surface of said outer race, said inner race, said outer race, said rolling elements and said shields being of magnetically permeable material; magnetic means for producing a magnetic field in said gaps and in regions where said rolling elements contact said inner race and said outer race; and a ferrofluid retained by said magnetic field in the gaps between said shields and said outer race and in the regions where said rolling elements contact said races, said ferrofluid permitting relative rotary movement of said housing and said shaft while sealing opposite ends of said bearing and lubricating said rolling elements and creating a reservoir to replenish any fluid loss, wherein at least a portion of each of said shields is angled toward said rolling elements, and said inner and outer races have equal axial dimensions.

Claim 3

A sealed bearing as defined in claim 1 wherein said magnetic means comprises one or more of said inner race, said outer race, said rolling elements and said shields being magnetized such that residual magnetism produces said magnetic field.

Claim 4

A sealed bearing as defined in claim 1 wherein said ferrofluid is electrically conducting to permit electrical connection between said inner race and said outer race through said ferrofluid and said shields and through said ferrofluid and said rolling elements.

Claim 5

A sealed bearing as defined in claim 1 wherein the annular region between said outer race and said inner race is substantially enclosed by said shields and contains the ferrofluid reservoir which lubricates said bearing and which replenishes ferrofluid in said gaps.

Claim 6

A sealed bearing as defined in claim 1 wherein said magnetic means includes an axially magnetized permanent magnet mounted on one end of said outer race and said housing is nonmagnetic.

Claim 7

A sealed bearing as defined in claim 5 wherein said permanent magnet is an annular ring coaxial with said outer race.

Claim 8

A sealed bearing as defined in claim 1 wherein said magnetic means includes axially magnetized permanent magnets mounted on each end of said outer race and said housing is nonmagnetic.

Claim 9

A sealed bearing as defined in claim 7 wherein said permanent magnets are annular rings coaxial with said outer race.

Claim 10

Apparatus for rotation of a load about an axis, comprising: a shaft of magnetic or nonmagnetic material aligned with the axis and coupled to the load; a housing including means for rotating said shaft about the axis relative to said housing; and a pair of rolling element bearings of magnetically permeable material axially spaced along said shaft to permit rotation of said shaft relative to said housing, each rolling element bearing comprising an inner race attached to said shaft, said inner race having an annular outer surface; an outer race concentric with said inner race and attached to said housing, said outer race having an annular inner surface; a plurality of rolling elements located in an annular region between said inner race and said outer race, a pair of shields attached to the outer surface of said inner race and extending outwardly from the outer surface of said inner race toward the inner surface of said outer race on opposite sides of said rolling elements so as to substantially enclose said annular region, each of said shields having a closely-spaced, noncontacting relationship with the inner surface of said outer race, thereby defining a gap between each of said shields and the inner surface of said outer race, magnetic means for producing a magnetic field in said gaps and in regions where said rolling elements contact said inner race and said outer race, and a ferrofluid retained by said magnetic field in the gaps between said shields and said outer race and in the regions where said rolling elements contact said races, said ferrofluid permitting relative rotary movement of said housing and said shaft while sealing opposite ends of said bearing and lubricating said rolling elements, wherein at least a portion of each of said shields is angled toward said rolling elements, and said inner and outer races have equal axial dimensions.

Claim 11

Apparatus for rotation of a load about an axis, comprising: a shaft of magnetic or nonmagnetic material aligned with the axis and coupled to the load; a housing including means for rotating said shaft about the axis relative to said housing; and a pair of rolling element bearings of magnetically permeable material axially spaced along said shaft to permit rotation of said shaft relative to said housing, each rolling element bearing comprising an inner race attached to said shaft, said inner race having an annular outer surface; an outer race concentric with said inner race and attached to said housing, said outer race having an annular inner surface; a plurality of rolling elements located in an annular region between said inner race and said outer race, a pair of shields attached to the outer surface of said inner race and extending outwardly from the outer surface of said inner race toward the inner surface of said outer race on opposite sides of said rolling elements so as to substantially enclose said annular region, each of said shields having a closely-spaced, noncontacting relationship with the inner surface of said outer race, thereby defining a gap between each of said shields and the inner surface of said outer race, magnetic means for producing a magnetic field in said gaps and in regions where said rolling elements contact said inner race and said outer race, and a ferrofluid retained by said magnetic field in the gaps between said shields and said outer race and in the regions where said rolling elements contact said races, said ferrofluid permitting relative rotary movement of said housing and said shaft while sealing opposite ends of said bearing and lubricating said rolling elements, wherein at least a portion of each of said shields is angled toward said rolling elements, and said inner and outer races have equal axial dimensions.

Claim 12

A sealed rolling element bearing for supporting a shaft of magnetic or nonmagnetic material and for permitting rotation of the shaft relative to a housing comprising: an inner race attachable to the shaft; an outer race concentric with said inner race and attachable to the housing; a plurality of rolling elements located in an annular region between said inner race and said outer race; a pair of shields extending outwardly from said inner race toward said outer race on opposite sides of said rolling elements so as to substantially enclose said annular region, said shields having a closely-spaced, noncontacting relationship with said outer race thereby defining a gap between each of said shields and said outer race, said inner race, said outer race, said rolling elements and said shields being of magnetically permeable material; magnetic means for producing a magnetic field in said gaps and in regions where said rolling elements contact said inner race and said outer race; and a ferrofluid retained by said magnetic field in the gaps between said shields and said outer race and in the regions where said rolling elements contact said races, said ferrofluid permitting relative rotary movement of said housing and said shaft while sealing opposite ends of said bearing and lubricating said rolling elements, wherein at least a portion of each of said shields is angled toward said rolling elements, and said inner and outer races have equal axial dimensions.

Claim 13

A sealed rolling element bearing for supporting a shaft of magnetic or nonmagnetic material and for permitting rotation of the shaft relative to a housing comprising: an inner race attachable to the shaft; an outer race concentric with said inner race and attachable to the housing; a plurality of rolling elements located in an annular region between said inner race and said outer race; a pair of shields extending outwardly from said inner race toward said outer race on opposite sides of said rolling elements so as to substantially enclose said annular region, said shields having a closely-spaced, noncontacting relationship with said outer race thereby defining a gap between each of said shields and said outer race, said inner race, said outer race, said rolling elements and said shields being of magnetically permeable material; magnetic means for producing a magnetic field in said gaps and in regions where said rolling elements contact said inner race and said outer race; and a ferrofluid retained by said magnetic field in the gaps between said shields and said outer race and in the regions where said rolling elements contact said races, said ferrofluid permitting relative rotary movement of said housing and said shaft while sealing opposite ends of said bearing and lubricating said rolling elements, wherein at least a portion of each of said shields is angled toward said rolling elements, and said inner and outer races have equal axial dimensions.

Claim 14

A sealed bearing as defined in claim 10 wherein said magnetic means comprises one or more of said inner race, said outer race, said rolling elements and said shields being magnetized such that residual magnetism produces said magnetic field.

Claim 15

A sealed bearing as defined in claim 10 wherein said ferrofluid is electrically conducting to permit electrical connection between said inner race and said outer race through said ferrofluid and said shields and through said ferrofluid and said rolling elements.

Claim 16

A sealed bearing as defined in claim 10 wherein the annular region between said outer race and said inner race is substantially enclosed by said shields and contains a ferrofluid reservoir which lubricates said bearing and which replenishes ferrofluid in said gaps.

Claim 17

A sealed bearing as defined in claim 10 wherein said magnetic means includes an axially magnetized permanent magnet mounted on one end of said outer race, and said housing is nonmagnetic.

Claim 18

A sealed bearing as defined in claim 14 wherein said permanent magnet is an annular ring coaxial with said outer race.

Claim 19

A sealed bearing as defined in claim 10 wherein said magnetic means includes axially magnetized permanent magnets mounted on each end of said outer race, and said housing is nonmagnetic.

Claim 20

A sealed bearing as defined in claim 16 wherein said permanent magnets are annular rings coaxial with said outer race.

Claim 21

Apparatus for rotation of a load about an axis, comprising: a shaft of magnetic or nonmagnetic material aligned with the axis and coupled to the load; a housing including means for rotating said shaft about the axis relative to said housing; and a pair of rolling element bearings of magnetically permeable material axially spaced along said shaft to permit rotation of said shaft relative to said housing, each rolling element bearing comprising; an inner race attached to said shaft; an outer race concentric with said inner race and attached to said housing; a plurality of rolling elements located in an annular region between said inner race and said outer race, a pair of shields extending outwardly from said inner race toward said outer race on opposite sides of said rolling elements so as to substantially enclose said annular region, said shields having a closely-spaced, noncontacting relationship with said outer race, thereby defining a gap between each of shields and said outer race, magnetic means for producing a magnetic field in said gaps and in regions where said rolling elements contact said inner race and said outer race, and a ferrofluid retained by said magnetic field in the gaps between said shields and said outer race and in the regions where said rolling elements contact said races, said ferrofulid permitting relative rotary movement of said housing and said shaft while sealing opposite ends of said bearing and lubricating said rolling elements, and creating a reservoir for continuous replenishment, and wherein at least a portion of each of said shields is angled toward said rolling elements, and said inner and outer races have equal axial dimensions.

Claim 22

Apparatus for rotation of a load about an axis, comprising: a shaft of magnetic or nonmagnetic material aligned with the axis and coupled to the load; a housing including means for rotating said shaft about the axis relative to said housing; and a pair of rolling element bearings of magnetically permeable material axially spaced along said shaft to permit rotation of said shaft relative to said housing, each rolling element bearing comprising; an inner race attached to said shaft; an outer race concentric with said inner race and attached to said housing; a plurality of rolling elements located in an annular region between said inner race and said outer race, a pair of shields extending outwardly from said inner race toward said outer race on opposite sides of said rolling elements so as to substantially enclose said annular region, said shields having a closely-spaced, noncontacting relationship with said outer race, thereby defining a gap between each of shields and said outer race, magnetic means for producing a magnetic field in said gaps and in regions where said rolling elements contact said inner race and said outer race, and a ferrofluid retained by said magnetic field in the gaps between said shields and said outer race and in the regions where said rolling elements contact said races, said ferrofulid permitting relative rotary movement of said housing and said shaft while sealing opposite ends of said bearing and lubricating said rolling elements, and creating a reservoir for continuous replenishment, and wherein at least a portion of each of said shields is angled toward said rolling elements, and said inner and outer races have equal axial dimensions.