US3874677A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High speed, self-acting shaft seal
Assignee: National Aeronautics and Space Administration
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Filing: 1973-07-19
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Granted: 1975-04-01
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Expires: 1993-07-19
Abstract
Abstract A high-speed, self-acting circumferential type shaft seal for use in turbine engines is disclosed. One or more conventional circumferential ring seals having a central aperture are mounted in a housing. In three of the four embodiments of the invention, a helical groove and one or more dam seals are cut in the inner cylindrical surface of the one or more ring seals. In a fourth embodiment, two or more lift pads are disposed in surface contact with the inner cylindrical surface of the seal rings. To the outside of the lift pads, two dam seals are cut in the inner cylindrical surface of two of the ring seals. In each of the embodiments, a net outward radial force is produced during rotation of the turbine causing the ring seals to lift out of contact with the turbine shaft to minimize wear of the ring seals.
Inventors
- 👤 Lawrence P Ludwig
- 👤 William F Hady
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 02:14
CPC Classifications
F; F16; F16J; F16J15/00; F16J15/44; F16J15/441; F16J15/16; F16J15/26; F16J15/30
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
121 words
A high-speed, self-acting shaft seal for use in sealing a rotating shaft between high and low pressure areas, the combination comprising: a housing; at least one ring seal disposed in said housing, said at least one ring seal having an aperture therein forming an inner cylindrical surface adapted to Be disposed around said rotating shaft; a dam seal at one end of said inner cylindrical surface of said at least one ring seal, and means coupled to said cylindrical surface of said at least one ring seal adjacent to said dam seal for producing a net outward radial force only during rotation of said shaft whereby said inner cylindrical surface lifts out of surface contact with said shaft during rotation thereof.
Claim 2
Dependent Claim
121 words
A high-speed, self-acting shaft seal for use in sealing a rotating shaft between high and low pressure areas, the combination comprising: a housing; at least one ring seal disposed in said housing, said at least one ring seal having an aperture therein forming an inner cylindrical surface adapted to Be disposed around said rotating shaft; a dam seal at one end of said inner cylindrical surface of said at least one ring seal, and means coupled to said cylindrical surface of said at least one ring seal adjacent to said dam seal for producing a net outward radial force only during rotation of said shaft whereby said inner cylindrical surface lifts out of surface contact with said shaft during rotation thereof.
Claim 3
Dependent Claim
97 words
A high-speed, self-acting shaft seal as recited in claim 1 wherein said means coupled to said inner cylindrical surface comprises: a helical groove cut in said inner cylindrical surface of said at least one ring seal; said helical groove extending from said high pressure area to said dam seal said dam seal forming a portion of said inner cylindrical surface; said helical groove producing an increasing pressure gradient from said high pressure area to said dam seal during rotation of said shaft; and said dam seal being disposed between said low pressure area and said helical groove.
Claim 4
Dependent Claim
159 words
A high-speed, self-acting shaft seal as recited in claim 1 wherein at least two seal rings are disposed in said housing, said means coupled to said inner cylindrical surface comprising: a pair of said dam seals, each dam seal being at one end of said cylindrical surface of a different one of said seal rings; each of said dam seals forming a portion of said inner cylindrical surface; a slot coupled to said high pressure area and being disposed between two of said at least two ring seals; a helical groove cut into said ring seals and extending from said slot to said pair of dam seals, said helical groove producing an increasing pressure gradient from said slot to said dam seals during rotation of said shaft; and said dam seals being respectively disposed between said high pressure area and one end of said helical groove and said low pressure area in the other end of said helical groove.
Claim 5
Dependent Claim
172 words
A high-speed, self-acting shaft seal as recited in claim 1 wherein at least two ring seals are disposed in said housing, said means coupled to said inner cylindrical surface comprising: a pair of dam seals disposed in surface contact with each other; each dam seal being at one end of said cylindrical surface of a different one of said ring seals; each of said dam seals forming a portion of said inner cylindrical surface; a first helical groove extending from said high pressure area to one of said dam seals, said first helical groove producing an increasing pressure gradient from said high pressure area to said one of said dam seals during rotation of said shaft; a second helical groove extending from the other of said dam seals to said low pressure area, and said low pressure area being adapted to be immersed within a liquid such as oil, whereby said second helical groove forces said liquid from said other dam seal to said low pressure area during rotation of said shaft.
Claim 6
Dependent Claim
143 words
A high-speed, self-acting shaft seal as recited in claim 1 wherein at least two seal rings are disposed in said housing, said means coupled to said inner cylindrical surface comprising: a pair of dam seals; each dam seal being at one end of said cylindrical surface of a different one of said seal rings; each of said dam seals forming a portion of said inner cylindrical surface; a slot coupled to said high pressure area and being disposed between two of said at least two seal rings; a plurality of lift pads being respectively disposed between said slot and one of said dam seals and said slot and the other of said dam seals; and said dam seals being disposed respectively between said high pressure area and one of said lift pads and said low pressure area and the other said lift pads.
Claim 7
Dependent Claim
105 words
A high-speed, self-acting shaft seal as recited in claim 5 wherein the plurality of lift pads comprises a ring having a central aperture therein forming an inner cylindrical surface adapted to be disposed around said shaft, adjacent lift pads being separated by longitudinally extending channels, said lift pads having a recess disposed therein, the cross-sectional shape of the lift pad defined from a radial direction with respect to said aperture, comprising a rectangular cross-section with a smaller cut-out cross-section having one of its edges in common with longitudinally extending channels, said smaller cut-out cross-section not bordering on any of the corners of said rectangular section.
Claim 8
Dependent Claim
79 words
A high-speed, self-acting shaft seal as recited in claim 2 wherein said dam seal has disposed therein a channel of a cross-sectional shape defined from a radial direction with respect to said aperture comprising: a rectangle with a smaller cut-out cross-section having one of its edges in common with said axially extending channel; said smaller cut-out cross-section not bordering on any of the corners of said rectangle; and said channel being coupled to said helical groove by a port.
Claim 9
Dependent Claim
83 words
A high-speed, self-acting shaft seal as recited in claim 3 wherein said dam seal has disposed therein a channel of a cross-sectional shape defined from a radial direction with respect to said aperture comprising: a rectangle with a smaller cut-out cross-section having one of its edges in common with said inner cylindrical surface of said dam seal; said smaller cut-out cross-section not bordering on any of the corners of said rectangle; and said channel being coupled to said helical groove by a port.
Claim 10
Dependent Claim
82 words
A high-speed, self-acting shaft as recited in claim 5 wherein said dam seal has disposed therein a channel of a cross-sectional shape defined from a radial direction with respect to said aperture comprising: a rectangle with a smaller cut-out section having one of its edges in common with said inner cylindrical surface of said dam seal; said smaller cut-out cross-section not bordering on any of the corners of said rectangle; and said channel being coupled to said helical groove by a port.
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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) | 1978-03-31 | 1978-09-30 | 1979-04-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-31 | 1982-09-30 | 1983-04-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-31 | 1986-09-30 | 1987-04-01 | $7700.00 | Window Closed / Lapsed |