US4254961A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Seal for fluid bearings
Assignee: Northrop Grumman Guidance and Electronics Co Inc
•
Filing: 1979-04-30
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Granted: 1981-03-10
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Expires: 1999-04-30
Abstract
Abstract Apparatus for containing a ferro-fluid within a reservoir of ferro-fluid using a pair of ferro-magnetic members adjacent each other and having opposing surfaces shaped as segments of surfaces of revolution, including magnetic apparatus for producing magnetic flux across the gap between the opposing surfaces. The surfaces diverge, and the greater magnetic flux density at the closely spaced edges of the pocket formed by the surfaces hold the ferro-magnetic particles of the ferro-fluid in that region. The volume between the two opposing surfaces is adequate to accommodate the thermal and pressure expansion and contraction of the fluid. The spacing between opposing members at the edge of farthest advance of the fluid is sufficiently small to allow the surface tension of the fluid to hold the fluid.
Inventors
- 👤 Rena S. Fersht
- 👤 Winston L. Skinner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 01:45
CPC Classifications
F; F16; F16C; F16C33/00; F16C33/02; F16C33/04; F16C33/06; F16C33/10; F16C33/1025; F16C33/103; F16C33/1035; F16C33/72; F16C33/74; F16C33/741; F16C33/743; F16C33/746; F16J; F16J15/00; F16J15/16; F16J15/40; F16J15/43; F16C2370/00
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
92 words
Apparatus for confining a ferro-fluid containing ferro-magnetic particles comprising: two ferro-magnetic members positioned adjacent each other to form a pocket therebetween for receiving a ferro-fluid, opposing surfaces of said two members having the shape of segments of surface of revolution, the opposing faces of said segments diverging from a close spacing adjacent said pocket toward a wider spacing away from said pocket on radii from the axis of revolution to cause a magnetic gradient between said ferro-magnetic members in a radial direction to force ferro-fluid toward and hold ferro-fluid in said pocket.
Claim 2
Dependent Claim
92 words
Apparatus for confining a ferro-fluid containing ferro-magnetic particles comprising: two ferro-magnetic members positioned adjacent each other to form a pocket therebetween for receiving a ferro-fluid, opposing surfaces of said two members having the shape of segments of surface of revolution, the opposing faces of said segments diverging from a close spacing adjacent said pocket toward a wider spacing away from said pocket on radii from the axis of revolution to cause a magnetic gradient between said ferro-magnetic members in a radial direction to force ferro-fluid toward and hold ferro-fluid in said pocket.
Claim 3
Dependent Claim
62 words
Apparatus for confining a ferro-fluid containing ferro-magnetic particles comprising: two ferro-magnetic members positioned adjacent each other to form a pocket therebetween for receiving a ferro-fluid, opposing surfaces of said two members having the shape of segments of surfaces of revolution, said two surfaces diverging from a close spacing on their radially outward edge toward a wider spacing on their radially inward edge.
Claim 4
Dependent Claim
62 words
Apparatus for confining a ferro-fluid containing ferro-magnetic particles comprising: two ferro-magnetic members positioned adjacent each other to form a pocket therebetween for receiving a ferro-fluid, opposing surfaces of said two members having the shape of segments of surfaces of revolution, said two surfaces diverging from a close spacing on their radially outward edge toward a wider spacing on their radially inward edge.
Claim 5
Dependent Claim
17 words
Apparatus as claimed in claim 1 in which at least one of said surfaces is conically shaped.
Claim 6
Dependent Claim
74 words
Apparatus for confining a ferro-fluid containing ferro-magnetic particles comprising: two ferro-magnetic members positioned adjacent each other to form a pocket therebetween for receiving a ferro-fluid, opposing surfaces of said two members having the shape of segments of surfaces of revolution, at least one of said surfaces being planar and perpendicular to the axis of revolution, said opposing surfaces diverging from a close spacing toward a wider spacing along radii from the axis of revolution.
Claim 7
Dependent Claim
74 words
Apparatus for confining a ferro-fluid containing ferro-magnetic particles comprising: two ferro-magnetic members positioned adjacent each other to form a pocket therebetween for receiving a ferro-fluid, opposing surfaces of said two members having the shape of segments of surfaces of revolution, at least one of said surfaces being planar and perpendicular to the axis of revolution, said opposing surfaces diverging from a close spacing toward a wider spacing along radii from the axis of revolution.
Claim 8
Dependent Claim
55 words
Apparatus for confining a ferro-fluid containing ferro-magnetic particles comprising: two ferro-magnetic members positioned adjacent each other to form a pocket therebetween for receiving a ferro-fluid, opposing surfaces being conical surfaces of revolution with different apex angles, said opposing surfaces diverging from a close spacing toward a wider spacing along radii from the axis of revolution.
Claim 9
Dependent Claim
55 words
Apparatus for confining a ferro-fluid containing ferro-magnetic particles comprising: two ferro-magnetic members positioned adjacent each other to form a pocket therebetween for receiving a ferro-fluid, opposing surfaces being conical surfaces of revolution with different apex angles, said opposing surfaces diverging from a close spacing toward a wider spacing along radii from the axis of revolution.
Claim 10
Dependent Claim
106 words
Apparatus for confining a ferro-fluid containing ferro-magnetic particles comprising: two ferro-magnetic members positioned adjacent each other to form a pocket therebetween for receiving a ferro-fluid, opposing surfaces of said two members having the shape of segments of surfaces of revolution, the shape of said segments diverging from a close spacing adjacent said pocket toward a wider spacing away from said pocket on radii from the axis of revolution, and a source of magnetism attached to said ferro-magnetic members to produce magnetic flux having a gradient in a radial direction across the gap between said opposing surfaces to force ferro-fluid toward and hold ferro-fluid in said pocket.
Claim 11
Dependent Claim
106 words
Apparatus for confining a ferro-fluid containing ferro-magnetic particles comprising: two ferro-magnetic members positioned adjacent each other to form a pocket therebetween for receiving a ferro-fluid, opposing surfaces of said two members having the shape of segments of surfaces of revolution, the shape of said segments diverging from a close spacing adjacent said pocket toward a wider spacing away from said pocket on radii from the axis of revolution, and a source of magnetism attached to said ferro-magnetic members to produce magnetic flux having a gradient in a radial direction across the gap between said opposing surfaces to force ferro-fluid toward and hold ferro-fluid in said pocket.
Claim 12
Dependent Claim
17 words
Apparatus as claimed in claim 2 in which at least one of said surfaces is conically shaped.
Claim 13
Dependent Claim
29 words
Apparatus as claimed in claim 7 and further comprising a source of magnetism attached to said ferro-magnetic members to produce magnetic flux across the gap between said opposing surfaces.
Claim 14
Dependent Claim
23 words
Apparatus as claimed in claim 2 in which at least one of said surfaces is planar and perpendicular to the axis of revolution.
Claim 15
Dependent Claim
29 words
Apparatus as claimed in claim 9 and further comprising a source of magnetism attached to said ferro-magnetic members to produce magnetic flux across the gap between said opposing surfaces.
Claim 16
Dependent Claim
18 words
Apparatus as claimed in claim 2 in which both said surfaces are conical but with different apex angles.
Claim 17
Dependent Claim
29 words
Apparatus as claimed in claim 11 and further comprising a source of magnetism attached to said ferro-magnetic members to produce magnetic flux across the gap between said opposing surfaces.
Claim 18
Dependent Claim
38 words
Apparatus as claimed in claim 8, 10 or 12, in which said source of magnetism is a permanent magnet together with ferro-magnetic flux conduits connecting opposing poles of said magnet to opposing surfaces of said ferro magnetic members.
Claim 19
Dependent Claim
28 words
Apparatus as recited in claim 8, 10 or 12, and further comprising reservoir means containing a ferro-fluid attached to the edges of said surfaces which are closest together.
Claim 20
Dependent Claim
136 words
Apparatus as recited in claim 8, 10 or 12, in which the flux density at the edge of narrowest spacing between said opposing surfaces is of sufficient magnitude to hold ferro-magnetic particles which are suspended in the ferro-fluid, the liquid portion of said ferro-fluid has a surface tension adequate to attach such fluid to the ferro-magnetic particles, the minimum spacing between said surfaces is small enough to produce said flux density, the volume between said surfaces in said pocket is adequate to allow for changes in volume of the ferro-fluid, and the spacing between said surfaces at the edge of the ferro-fluid during maximum expansion of such fluid is narrow enough to allow the surface tension of said fluid to hold the fluid in a force balance generated by the steady magnetic field and surface tension.
Claim 21
Dependent Claim
34 words
Apparatus as claimed in claim 6 in which said source of magnetism is a permanent magnet together with ferro-magnetic flux conduits connecting opposing poles of said magnet to opposing surfaces of said ferro-magnetic members.
Claim 22
Dependent Claim
25 words
Apparatus as recited in claim 6, and further comprising reservoir means containing a ferro-fluid attached to the edges of said surfaces which are closest together.
Claim 23
Dependent Claim
133 words
Apparatus as recited in claim 6 in which the flux density at the edge of narrowest spacing between said opposing surfaces is of sufficient magnitude to hold ferro-magnetic particles which are suspended in the ferro-fluid, the liquid portion of said ferro-fluid has a surface tension adequate to attach such fluid to the ferro-magnetic particles, the minimum spacing between said surfaces is small enough to produce said flux density, the volume between said surfaces in said pocket is adequate to allow for changes in volume of the ferro-fluid, and the spacing between said surfaces at the edge of the ferro-fluid during maximum expansion of such fluid is narrow enough to allow the surface tension of said fluid to hold the fluid in a force balance generated by the steady magnetic field and surface tension.
References Cited (Backward Citations)
US2557140A
Cited
GB680233A
Cited
GB783881A
Cited
US2996162A
Cited
US3475975A
Cited
US3483969A
Cited
US3612630A
Cited
US3620584A
Cited
US3726574A
Cited
US3746407A
Cited
US3780593A
Cited
SU494553A1
Cited
US3891282A
Cited
US3918773A
Cited
SU550499A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-03-09 | 1984-09-08 | 1985-03-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-09 | 1988-09-08 | 1989-03-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-09 | 1992-09-08 | 1993-03-10 | $7700.00 | Window Closed / Lapsed |