US4797013A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Compact ferrofluidic electrically conducting sealed bearing
Assignee: Ferrofluidics Corp
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Filing: 1987-02-09
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Granted: 1989-01-10
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Expires: 2007-02-09
Abstract
Abstract A sealed, rolling element bearing includes an inner race attached to a shaft, an outer race attached to a housing, a plurality of rolling elements in an annular region and a pair of shields extending inwardly from the outer race toward the inner race so as to substantially enclose the annular region. The shields have a closely-spaced, noncontacting relationship with the inner race thereby defining gaps. The elements of the bearing are of magnetically permeable material, and the sealed bearing includes means for producing a magnetic field in the gaps and in the regions where the rolling elements contact the races. A ferrofluid is retained by the magnetic field in the gaps for sealing and in the regions of contact between the rolling elements and the races for lubrication. A reservoir of ferrofluid in the regions between the two seals replenishes ferrofluid lost at the sealing and lubrication areas. The magnetic field can be produced by permanent magnetization of the bearing assembly or by axially polarized permanent magnets located on either or both ends of the outer race. Such a bearing may be used with a magnetic or nonmagnetic shaft and permits relative motion between the shaft and the housing. The housing material is of nonmagnetic type when external magnets are used.
Inventors
- 👤 Kuldip Raj
- 👤 Hanumaiah L. Gowda
- 👤 Ronald Moskowitz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 01:56
CPC Classifications
G; G11; G11B; G11B19/00; G11B19/20; G11B19/2009; F; F16; F16C; F16C33/00; F16C33/30; F16C33/66; F16C33/6637; F16C33/664; F16C33/6644; F16C33/6688; F16C33/72; F16C33/76; F16C33/762; F16C33/763; F16C33/765; F16C41/00; F16C41/002; F16J; F16J15/00; F16J15/16; F16J15/40; F16J15/43; F16C2370/00; F16C2370/12
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
239 words
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 inwardly from said outer race toward said inner 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 inner race thereby defining a gap between each of said shields and said inner 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 inner 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 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 2
Dependent Claim
239 words
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 inwardly from said outer race toward said inner 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 inner race thereby defining a gap between each of said shields and said inner 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 inner 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 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
Dependent Claim
39 words
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
Dependent Claim
40 words
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
Dependent Claim
42 words
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 a ferrofluid reservoir which lubricates said bearing and which replenishes ferrofluid in said gaps.
Claim 6
Dependent Claim
31 words
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
Dependent Claim
21 words
A sealed bearing as defined in claim 5 wherein said permanent magnet is an annular ring coaxial with said outer race.
Claim 8
Dependent Claim
30 words
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
Dependent Claim
20 words
A sealed bearing as defined in claim 7 wherein said permanent magnets are annular rings coaxial with said outer race.
Claim 10
Dependent Claim
275 words
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 inwardly from said outer race toward said inner 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 inner race, thereby defining a gap between each of said shields and said inner 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 inner 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 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 11
Dependent Claim
275 words
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 inwardly from said outer race toward said inner 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 inner race, thereby defining a gap between each of said shields and said inner 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 inner 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 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.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-01-10 | 1992-07-11 | 1993-01-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-01-10 | 1996-07-11 | 1997-01-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-01-10 | 2000-07-11 | 2001-01-10 | $7700.00 | Window Closed / Lapsed |