Seal for a joint or juncture – Seal between fixed parts or static contact against... – Contact seal between parts of internal combustion engine
Reexamination Certificate
1999-04-08
2001-09-04
Knight, Anthony (Department: 3628)
Seal for a joint or juncture
Seal between fixed parts or static contact against...
Contact seal between parts of internal combustion engine
C277S592000, C277S650000
Reexamination Certificate
active
06283479
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to a gas turbine engine and more particularly to a low leakage non-metallic seal interposed a high pressure fluid and a low pressure fluid being positioned about a rotating shaft.
BACKGROUND ART
Gas turbine engine performance is very dependent on maintaining a tight seal between a high pressure region and a low pressure region. These regions are present throughout the gas turbine engine including regions between the turbine stages, compressor stages, and other locations.
To add to the complexity of sealing the high pressure region from the low pressure region, many of the seals in the gas turbine engine are established between moving parts. In one particular application, a shaft seal prevents a hot, high pressure gas from moving between a housing and a rotating shaft into a low pressure gas. Current sealing arrangements such as C-seals, E-seals, bellows seals, and Garlock seals tend to wear quickly. The wear of these seals is further exacerbated by leakage through these seals.
Some manufacturers use a plurality of non-metallic seals in a piston ring fashion. These seals may work well in a low temperature environment. However, the non-metallic seals tend to have reduced mechanical strength at higher temperatures. The reduced mechanical strength allows the seals to lose their shape or fail to return to their original shape. Leaking increases as the seals loose their mechanical strength. At higher temperatures, the leakage rates will oxidize the seal and further increase leakage. In some instances leakage may create problems controlling the gas turbine engine.
The present invention is directed to overcome one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of the invention, a seal is formed between a shaft and a housing. The seal has a first plate disposed about a circumference of the shaft and an inner periphery of the housing. The first plate has a first side and a second side. The first side of the first plate is exposed to a low pressure fluid. The first plate has high temperature mechanical strength and is adapted to provide structural support. A non-metallic plate is disposed about the circumference of the shaft and the inner periphery of the housing. The non-metallic plate has a first side and a second side. The first side of the non-metallic plate is adjacent to the second side of the first plate. The second side of the non-metallic plate is adjacent to a high pressure fluid. The non-metallic plate has a glass transition temperature above a predetermined temperature.
In another aspect of the invention, a method is defined for sealing a high pressure fluid on a first side of a shaft from a low pressure fluid on a second side. The high pressure fluid is separated from the low pressure fluid with a non-metallic material having a glass transition temperature above an operating temperature of the high pressure fluid. The non-metallic material is supported structurally to maintain a predetermined shape.
In a further aspect of the invention, a control system for a gas turbine engine has a sealing arrangement. The sealing arrangement has a housing with a first portion and a second portion. The second portion is spaced from the first portion. The first portion is proximate a low pressure fluid. The second portion is proximate a high pressure fluid. A shaft is disposed in the housing. The first seal is disposed proximate the first portion. The first seal is intermediate the shaft and the housing. The first seal has high temperature mechanical strength. A non-metallic seal is disposed intermediate the first seal and the second portion. The non-metallic seal is intermediate the shaft and the housing. The non-metallic seal has a glass transition temperature above an operating temperature of the high pressure fluid.
REFERENCES:
patent: 3907311 (1975-09-01), Rao
patent: 4486002 (1984-12-01), Riess et al.
patent: 4704332 (1987-11-01), Brennan et al.
patent: 5014999 (1991-05-01), Makhobey
patent: 5217232 (1993-06-01), Makhobey
patent: 5221096 (1993-06-01), Heldreth et al.
patent: 5292138 (1994-03-01), Glynn et al.
patent: 5305609 (1994-04-01), Guinan et al.
patent: 5346136 (1994-09-01), Bassett
patent: 6003792 (1999-12-01), Munezane et al.
Hewitt James M.
Knight Anthony
Roberson Keith P.
Solar Turbines Incorporated
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