Rotary kinetic fluid motors or pumps – With lubricating – sealing – packing or bearing means having... – For shaft sealing – packing – lubricating or bearing means
Reexamination Certificate
1998-12-17
2001-03-06
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
With lubricating, sealing, packing or bearing means having...
For shaft sealing, packing, lubricating or bearing means
C415S174200, C415S231000
Reexamination Certificate
active
06196790
ABSTRACT:
DESCRIPTION
1. Technical Field
This invention relates to a seal assembly for a gas turbine engine and more particularly to a seal assembly for an intershaft seal that seals between coaxial rotor shafts in a multiple spool gas turbine engine.
2. Background Art
A front bearing compartment in a multiple spool gas turbine engine is filled with an oil mist to lubricate bearings that support an inner rotor shaft and an outer rotor shaft. The inner and the outer rotor shafts are separated by a gap filled with working medium gas. The working medium gas provides cooling for the rotor shafts, but is warmer than the temperature inside the bearing compartment. An intershaft seal prevents the working medium gas from leaking into the oil compartment and prevents the oil mist from leaking oil out of the compartment into the gap. The intershaft seal traditionally employs two face seals, to seal to the shafts, and a ring seal therebetween, to limit leakage between the face seals.
In order to maximize performance and efficiency, many advanced gas turbine engines operate at very demanding engine conditions, e.g., temperatures, pressures, and rotational speeds. In some of these engines, such conditions sometimes cause the traditional intershaft seals to wear at a rate that is higher than desired. Prior efforts to improve the durability of the seals include using more durable materials and reducing clearances in the seal. These solutions have not eliminated the higher wear rates.
Scientists and engineers working under the direction of Applicants' assignee have been working to provide other solutions to further improve the durability of intershaft seals.
DISCLOSURE OF THE INVENTION
An object of the present invention is to improve the durability of intershaft seals.
The present invention is predicated, in part, on the recognition that flex in the ring seal of the traditional intershaft seal makes the ring seal a primary limiting factor in the durability of the traditional intershaft seal, and that such flex can be eliminated by replacing the traditional ring seal with an intermediate seal supported by the stator assembly to seal between the two face seals.
According to the present invention a seal assembly for use in an intershaft seal includes a first seal that seals to an inner rotor shaft, a second seal that seals to an outer rotor shaft, and an intermediate seal supported by the stator assembly for sealing between the first seal and the second seal.
The seal assembly of the present invention employs an intermediate seal that is supported by the stator assembly to seal between the face seals. Consequently, an intershaft seal employing the seal assembly of the present invention has less flex than the traditional intershaft seal, which results in greater durability and less seal wear than that of the traditional intershaft seal. In a detailed embodiment, the present invention provides these improvements without adding unreasonable complexity or taking up much more room than the traditional intershaft seal, and has a symmetry that facilitates part commonality.
These and other objects, features and advantages of the present invention will become more apparent in the light of the following detailed description, accompanying drawings, and claims.
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Shaffer Harold K.
Sheridan William G.
Look Edward K.
Nguyen Ninh
Steinberg Mark
United Technologies Corporation
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