US4645960A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ferro-fluid bearing
Assignee: Northrop Grumman Guidance and Electronics Co Inc
•
Filing: 1980-11-24
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Granted: 1987-02-24
•
Expires: 2000-11-24
Abstract
Abstract A bearing having a cylindrical bore and a shaft in the bore with ferrofluid between the shaft and the bore walls. The cylindrical bearing is made of ferromagnetic material, and it is magnetized with its internal magnetization radially directed relative to the axis of the bore. Also pertains to a method for making and magnetizing the bearing.
Inventors
- 👤 George J. Hoffman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 05:43
CPC Classifications
F; F16; F16C; F16C33/00; F16C33/72; F16C33/74; F16C33/02; F16C33/04; F16C33/06; F16C33/10; F16C33/1025; F16C33/103; F16C33/1035
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
125 words
A ferro-fluid bearing for supporting a circularly cylindrical shaft comprising: a circularly cylindrical shaft; a permanent magnet bearing structure forming a circular cylindrical bore for surrounding said circularly cylindrical shaft, the diameter of said circularly cylindrical bore being larger than the outer diameter of said shaft, said bearing structure having the same poled radially directed internal magnetization along the entire length of said bore and around the entire circumference of said bore so there exists at substantially all regions of the surface of said bore the same pole face producing radially directed magnetic flux at said pole face and thence into the region between said pole face and said shaft; a ferro-fluid between the surface of said bore of said bearing structure and said shaft.
Claim 2
Dependent Claim
125 words
A ferro-fluid bearing for supporting a circularly cylindrical shaft comprising: a circularly cylindrical shaft; a permanent magnet bearing structure forming a circular cylindrical bore for surrounding said circularly cylindrical shaft, the diameter of said circularly cylindrical bore being larger than the outer diameter of said shaft, said bearing structure having the same poled radially directed internal magnetization along the entire length of said bore and around the entire circumference of said bore so there exists at substantially all regions of the surface of said bore the same pole face producing radially directed magnetic flux at said pole face and thence into the region between said pole face and said shaft; a ferro-fluid between the surface of said bore of said bearing structure and said shaft.
Claim 3
Dependent Claim
52 words
Apparatus as recited in claim 1 in which said bearing structure is magnetized with a first one of the pole faces on the non-bore surface of said structure and the second pole face on substantially all regions along the entire length and around the entire circumference of the surface of said bore.
Claim 4
Dependent Claim
33 words
Apparatus as recited in claim 2 in which said bearing structure is fabricated of material comprising a platinum cobalt alloy, and said shaft is fabricated with at least its surface of ferromagnetic material.
Claim 5
Dependent Claim
34 words
Apparatus as recited in claim 2 in which said bearing structure is fabricated of a material comprising a rear earth alloy, and said shaft is fabricated with at least its surface of ferromagnetic material.
Claim 6
Dependent Claim
34 words
Apparatus as recited in claim 2 in which said bearing structure is fabricated of a material comprising a samarium cobalt alloy, and said shaft is fabricated with at least its surface of ferromagnetic material.
Claim 7
Dependent Claim
36 words
Apparatus as recited in claim 2 in which said bearing structure is divided into contacting attached axial slices from one end to the other by radial planes extending from and including the axis of said bore.
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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) | 1990-02-23 | 1990-08-25 | 1991-02-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-23 | 1994-08-25 | 1995-02-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-23 | 1998-08-25 | 1999-02-24 | $7700.00 | Window Closed / Lapsed |