US5050891A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sealing member for ferrofluid seal
Assignee: Nippon Ferrofluidics Corp
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Filing: 1989-03-31
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Granted: 1991-09-24
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Expires: 2009-03-31
Abstract
Abstract A sealing member for a ferrofluid seal according to the present invention is a sealing member (1) arranged so as to surround a periphery of a working member (5) such as a shaft. The sealing member (1) comprises an annular magnet (2) and an annular pole piece (3), an electrically conductive ferrofluid (6) being provided between the sealing member (1) and the working member (5) to construct an electrically conductive magnetic fluid-sealing member. An inner circumferential surface of the annular magnet (2) is coated with an electrically conductive non-magnetic film (4 ) continuing to the annular pole piece (3) to reduce size of the sealing member (1) and reduce electrical resistance.
Inventors
- 👤 Ryuhei Ishikawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:59
CPC Classifications
F; F16; F16J; F16J15/00; F16J15/16; F16J15/40; F16J15/43; Y; Y10; Y10S; Y10S277/00; Y10S277/919
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
87 words
A sealing member for a ferrofluid seal to be disposed so as to surround an external circumference of a working member such as a shaft, said sealing member comprising: an annular magnet and annular pole pieces arranged at each side thereof and forming an electrically conductive ferrofluid seal by interposing an electrically conductive ferrofluid between the sealing member and the working member; and an electrically conductive nonmagnetic coating on internal circumferential surfaces of said magnet and pole pieces, wherein said coating extends over said annular pole pieces.
Claim 2
Dependent Claim
87 words
A sealing member for a ferrofluid seal to be disposed so as to surround an external circumference of a working member such as a shaft, said sealing member comprising: an annular magnet and annular pole pieces arranged at each side thereof and forming an electrically conductive ferrofluid seal by interposing an electrically conductive ferrofluid between the sealing member and the working member; and an electrically conductive nonmagnetic coating on internal circumferential surfaces of said magnet and pole pieces, wherein said coating extends over said annular pole pieces.
Claim 3
Dependent Claim
24 words
A sealing member for a ferrofluid seal according to claim 1, wherein the nonmagnetic coating extends over all external surfaces of the sealing member.
References Cited (Backward Citations)
GB1292338A
Cited
SU889988A1
Cited
SU694710A1
Cited
US4357022A
Cited
US4592557A
Cited
JPS63152773A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-09-23 | 1995-03-25 | 1995-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-23 | 1999-03-25 | 1999-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-23 | 2003-03-25 | 2003-09-24 | $7700.00 | Window Closed / Lapsed |