Compact ferrofluidic electrically conducting sealed bearing

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.

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.

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.