Patent Application
20130113168
This disclosure generally relates to a gasket seal, and more particularly to a gasket air seal for sealing gaps between multiple relative moving parts.
A turbine engine includes multiple gaskets of varying sizes and shapes to control leakage and gas flow. Many of the gaskets seal gaps are defined between multiple independently moving parts. Accordingly, any gasket is required to seal against undesired leakage, but also accommodate relative movement between parts. Moreover, each gasket must provide a level of durability capable of withstanding wear encountered as a result of relative movement.
A disclosed example gasket assembly for a gas turbine engine according to an exemplary embodiment includes a seal portion defining outer surfaces for providing sealing contact and a bias portion defining inner structures that are spaced apart from the seal portion for biasing the outer surfaces into sealing contact. The gasket further includes end portions disposed at ends of the seal portion that include a material thickness greater than a thickness of the bias portion.
In a further embodiment of the gasket assembly, the gasket assembly comprises a single continuous structure and the end portions define distal ends of the continuous structure.
In a further embodiment of the foregoing gasket assembly, the bias portion includes inner legs spaced apart inward of the outer surfaces.
In a further embodiment of the foregoing gasket assembly, the end portions include a thickness greater than a thickness of the outer legs.
In a further embodiment of the foregoing gasket assembly the end portions are disposed substantially transverse to the outer surfaces.
In a further embodiment of the foregoing gasket assembly the end portions define an end surface for providing sealing contact against a surface different than a surface contacted by the outer surface of the sealing portion.
In a further embodiment of the foregoing gasket assembly, the gasket assembly includes a substantially W-shape cross-section.
In a further embodiment of the foregoing gasket assembly, the bias portion includes an inner W-shaped cross-section.
A gasket assembly for a gas turbine engine according to another exemplary embodiment of the present disclosure includes a cavity defined about an axis of the gas turbine engine between a first surface and a second surface movable relative to each other and a gasket disposed within the cavity. The gasket including a seal portion including outer surfaces in sealing contact with each of the first and second surfaces, a bias portion biasing the outer surfaces into sealing contact with each of the first and second surfaces, and end portions disposed at ends of the outer surfaces including a first thickness greater than a second thickness of the bias portion.
In a further embodiment of the foregoing gasket assembly embodiment, the first and second surfaces are substantially parallel to each other and the cavity includes a third surface transverse to the first and second surfaces.
In a further embodiment of the foregoing gasket assembly embodiment, the cavity is annular about the axis and the first and second surfaces are disposed transverse to the axis.
In a further embodiment of the foregoing gasket assembly embodiment, the gasket comprises a W-shaped cross-section including an inner W-shaped portion spaced apart from the outer surfaces.
In a further embodiment of the foregoing gasket assembly embodiment, the inner W-shaped portion comprises the bias portion.
In a further embodiment of the foregoing gasket assembly embodiment, the end portions are disposed at terminal ends of the seal portion.
In a further embodiment of the foregoing gasket assembly embodiment, the second thickness of the bias portion defines a biasing force for biasing the seal portions into sealing contact with the first and second surfaces.
A method of forming a gasket assembly according to another exemplary embodiment of this disclosure includes forming a substantially planar metal strip to include a first thickness at end portions greater than a second thickness at a midpoint between the end portions, and forming the planar metal strip into a substantially W-shaped cross-section including outer sealing surfaces and an inner W-shaped portion defining a biasing portion with the end portions disposed at distal ends of the outer sealing surfaces.
In a further embodiment of the foregoing method of forming a seal assembly the method includes the step of forming the end portions to extend substantially transverse to the outer surfaces.
In a further embodiment of the foregoing method of forming a gasket assembly the method includes the step of extending the cross-section of the gasket assembly a length transverse to the W-shaped cross-section.
In a further embodiment of the foregoing method of forming a gasket assembly the method includes spacing the inner W-spaced portion inward of the outer surfaces for separating the sealing portion from the biasing portion.
Although different examples have the specific components shown in the illustrations, embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components of another of the examples.
These and other features disclosed herein can be best understood from the following specification and drawings, the following of which is a brief description.
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Air drawn in through the compressor section 14 is compressed and fed into the combustor 20. In the combustor 20, the compressed air is mixed with fuel and ignited to generate a high speed gas stream. This gas stream is exhausted from the combustor 20 to drive the turbine section 24. The fan section 12 is driven through a gearbox 32 by the low spool 28.
The engine 10 in the disclosed embodiment is a high-bypass geared architecture aircraft engine. In one disclosed embodiment, the engine 10 bypass ratio is greater than ten (10:1), the turbofan diameter is significantly larger than that of the low pressure compressor 16, and the low pressure turbine 24 has a pressure ratio that is greater than 5:1. The gear train 32 may be an epicycle gear train such as a planetary gear system or other gear system with a gear reduction ratio of greater than 2.5:1. It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present application is applicable to other gas turbine engines including direct drive turbofans.
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Biasing force is a function of a second thickness 60 within the biasing portion 54. The thicker the material in the biasing portion 54, the greater the biasing force exerted on the outer surfaces 62 of the corresponding seal portions 52. The example gasket 50 includes a first thickness of the end portions 56 that is greater than the second thickness 60 in the biasing portion 54. The biasing force is defined to provide a desired contact pressure of the outer surfaces 62 against the corresponding first and second surfaces 36, 38 while not exerting a force that could restrict desired operation.
The sealing portions 52, biasing portion 54 and end portions 56 are part of a single continuous structure that defines a generally W-shaped cross-sectional shape of the gasket 50. The biasing portion 54 includes a substantially inner W-shaped portion 66 that is spaced apart from outer surfaces 62. The inner W-shaped portion 66 includes inner legs 64 that extend from a curved portion 70. The inner legs 64 are spaced apart inward of the sealing portions 52 that include the outer surface 62. The central curved portion 70 provides for an outward bias against the sealing portions 52.
The end portions 56 include the first material thickness 58 that is greater than other portions of the gasket 50 including the second thickness 60 of the biasing portion 54. The increased thickness 58 disposed within the end portions 56 prevent premature wear through of the end portions 56 at the contact points 47.
The seal portion 52 is separated and spaced apart from the biasing portion 54 such that the sealing and biasing functions are separated. The spacing apart or separation of the biasing function from the sealing function extends the duration for which the gasket is operable and prevents premature wear through during operation of the gasket 50.
The first thickness 58 provided by the end portions 56 is not compatible with the desired biasing force provided by the biasing portion 54. Accordingly, the second thickness 60 within the biasing portion 54 is less than the first thickness 58. The thickness 60 is determined to be that thickness which provides the desired biasing force to seal the sealing portions 52 without adversely affecting operation or constraining movement of the relative moving parts. Accordingly, the end portions 56 include the thickness 58 that is greater than all other portions of the gasket 50.
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Once the material has been formed to include the desired first and second thicknesses, 78, 80, the material is formed to provide the desired generally W-shaped cross-section. In a first forming step indicated at 88, a beginning shape of the gasket 50 is formed. In this example, the formation steps are accomplished through a series of pressing dies that transform the material into the desired cross-sectional shape. However, other processes that are known in the art can be utilized to provide the desired shape of the gasket 50.
A first intermediate bend illustrated at 90 includes a further definition of the biasing portion 54 along with the outer sealing surfaces 62. A third intermediate forming operation indicated at 92, further bends and defines the biasing portion 54 and extends the sealing surfaces 62 of the sealing portion outwardly.
Forming step indicated at 94 provides a substantially complete cross-sectional shape of the gasket 50. The final bending operation 94 forms the biasing portion 54 and wraps the sealing portions 52 around and spaced part from the biasing portion 54. The example completed gasket 50 includes the inner W-shaped portion 66 that is spaced inwardly apart from the outer sealing surfaces 62. The end portions are wrapped around and substantially underneath the biasing portion 54 to contact surfaces transverse to the surfaces contacted by the outer surfaces 62. It should be understood, that although a certain number and sequence of forming steps are described by way of example, other steps and sequences of bending and forming operations could also be utilized to generate the substantially W-shaped gasket 50.
The completed gasket 50 may be coated with an anti-wear coating as is schematically shown at 96. The anti-wear coating is shown applied to the entire gasket 50, but may also be applied to only the contact surfaces. The coating may be utilized to further improve the wear properties of the gasket 50. Accordingly, the example gasket 50 provides increased durability while maintaining the desired sealing capacity without performance of the gasket part 50.
Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. For that reason, the following claims should be studied to determine the scope and content of this invention.
