US3740060A
Expired / Lapsed
US
⏱️ 0.0 years remaining
A shaft seal
Assignee: Avco Corp
•
Filing: 1971-11-03
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Granted: 1973-06-19
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Expires: 1991-11-03
Abstract
Abstract The invention relates to a shaft seal using a magnetic fluid to seal the clearance gap between a shaft and the housing. The magnetic fluid is held in place by a magnetic field. A modular structure is described which acts as a fluid reservoir, and a magnetic pole piece. The modular structure may also have inherent staging.
Inventors
- 👤 G Miskolczy
- 👤 R Kaiser
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 13:35
CPC Classifications
F; F16; F16J; F16J15/00; F16J15/16; F16J15/40; F16J15/43; Y; Y10; Y10S; Y10S277/00; Y10S277/928
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
79 words
A magnetic fluid shaft seal for sealing the clearance gap between a housing and a shaft, said seal comprising: a magnet having pole pieces having pores defined therein spaced from a shaft and defining with the shaft a clearance gap and a magnetic field bridging the gap, said porous pole pieces being in fluid communication with said clearance gap; and a ferrofluid disposed in the pores of said pole pieces and in said magnetic field in the clearance gap.
Claim 2
Dependent Claim
79 words
A magnetic fluid shaft seal for sealing the clearance gap between a housing and a shaft, said seal comprising: a magnet having pole pieces having pores defined therein spaced from a shaft and defining with the shaft a clearance gap and a magnetic field bridging the gap, said porous pole pieces being in fluid communication with said clearance gap; and a ferrofluid disposed in the pores of said pole pieces and in said magnetic field in the clearance gap.
Claim 3
Dependent Claim
17 words
A magnetic fluid shaft seal as described in claim 1 wherein the pole pieces are wire structures.
Claim 4
Dependent Claim
18 words
A magnetic fluid shaft seal as described in claim 2 wherein said wire structure is a non-woven structure.
Claim 5
Dependent Claim
21 words
A magnetic fluid shaft seal as described in claim 2 wherein said wire structure comprises a plurality of adjacent wire screens.
Claim 6
Dependent Claim
26 words
A magnetic fluid shaft seal as described in claim 1 wherein the magnet has a pair of spaced pole pieces separated by a porous non-magnetic member.
Claim 7
Dependent Claim
86 words
A magnetic fluid shaft seal for sealing the clearance gap between a housing and a shaft, said seal comprising: a magnet having pole pieces spaced remotely from a shaft; a porous bushing disposed between a pole piece and said shaft, said bushing defining a clearance gap with said shaft and a magnetic field across the clearance gap, said bushing being in fluid communication with said clearance gap; and a ferrofluid disposed in the pores of said bushing and in said magnetic field in the clearance gap.
Claim 8
Dependent Claim
86 words
A magnetic fluid shaft seal for sealing the clearance gap between a housing and a shaft, said seal comprising: a magnet having pole pieces spaced remotely from a shaft; a porous bushing disposed between a pole piece and said shaft, said bushing defining a clearance gap with said shaft and a magnetic field across the clearance gap, said bushing being in fluid communication with said clearance gap; and a ferrofluid disposed in the pores of said bushing and in said magnetic field in the clearance gap.
Claim 9
Dependent Claim
22 words
A magnetic fluid shaft seal as described in claim 6 wherein the porous bushings comprise alternately side-by-side spaced magnetic and non-magnetic members.
Claim 10
Dependent Claim
30 words
A magnetic fluid shaft seal as defined in claim 1 where the strength of the magnet is adjusted to cause the ferrofluid to be punctured by a predetermined pressure differential.
References Cited (Backward Citations)
US2557140A
Cited
US2834618A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-18 | 1976-12-18 | 1977-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-18 | 1980-12-18 | 1981-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-18 | 1984-12-18 | 1985-06-19 | $7700.00 | Window Closed / Lapsed |