SEAL ASSEMBLY
A seal assembly comprising a first movable stator member movable between a sealing position and a non-sealing position, a second fixed stator member, the first stator member being movable relative to the second stator member, the seal assembly further comprising at least one flexure member coupled to the second stator member, and at least one biasing member coupled between the at least one flexure and the movable stator for biasing the movable stator to a non-sealing position.
This application is a continuation-in-part of U.S. patent application Ser. No. 11/830,236 filed Jul. 30, 2007.
FIELD OF THE INVENTIONThe invention generally relates to gas turbine engines and more specifically to seal assemblies used with gas turbine engines.
BACKGROUND OF THE INVENTIONGas turbine engines displace large volumes of pressurized fluid, such as air through the engine fluid flowpath, during operation. Seal assemblies prevent the fluid from leaking undesirably by restricting fluid flow from areas of higher pressure to areas of lower pressure. The seal assemblies may be positioned between engine stationary and rotating members. The seals compensate for transient variations in the gaps between adjacent engine component parts.
Because of the working environment of the seal assemblies, and/or the operating environment, at least some known seal assemblies may deteriorate over time. If the seals do not provide the required seal, fluid will leak past the seal detrimentally affecting the operation of the engine. Fluid leakage through gas turbine engine seal assemblies may significantly increase fuel consumption and adversely affect engine efficiency. Additionally, fluid leakage may cause damage to other engine components and increase overall engine maintenance costs.
To facilitate sealing gaps defined between regions of high and low pressure at least some known seal assemblies, such as the seal assembly described in U.S. Pat. No. 5,284,347, for example, use aspirating air to control leakage. The aspirating air prevents the rotating member from contacting the stationary member to facilitate accommodating transient variations in the gap defined between the rotating and stationary members with little or no deterioration of the seal over the life of the seal assembly. However, because of the number of discrete components comprising such a seal assembly, such seal assemblies may be complex to install in the engine, and the weight of such assemblies will increase engine weight which has a direct negative impact on engine performance. Moreover, because of the number of seal assembly components, the operating efficiency of such seal assemblies may be contingent on the tolerances between the rotating and stationary members.
There is a need to develop a seal assembly that has relatively few parts, effectively prevents leakage of fluid within a turbine engine and does not deteriorate over time.
BRIEF DESCRIPTION OF THE INVENTIONA seal assembly comprising a first movable stator member movable between a sealing position and a non-sealing position, a second fixed stator member, the first stator member being movable relative to the second stator member, the seal assembly further comprising at least one flexure member coupled to the second stator member, and at least one biasing member coupled between the at least one flexure and the movable stator for biasing the movable stator to a non-sealing position.
While the specification concludes with claims particularly pointing out and distinctly claiming the invention, it is believed that the embodiments set forth herein will be better understood from the following description in conjunction with the accompanying figures, in which like reference numerals identify like elements, and in which:
Although the invention is herein described and illustrated in association with a compressor to turbine interface for a gas turbine engine, it should be understood that the present invention may be used to facilitate controlling leakage of any fluid between any region of generally high pressure and any region of lower pressure.
Herein, the present invention seal assembly provides a simplified seal with a reduced part count relative to prior art seals thereby simplifying the seal assembly, and reducing the weight of the seal assembly. For example, spring assemblies used in related seal assemblies have been replaced by one or more flexure members. As will be described herein the flexure member is attached between a non-contact seal slide and a stator. Also, secondary seal assemblies of prior art sealing devices have been replaced with a single piston ring seal. The single ring seal may be retained within either a fixed or sliding stators. The design may incorporate one or more flexure members, the number thereof depending upon the design requirement.
During operation, air flows axially through fan assembly 12, in a direction that is substantially parallel to a central axis 34 extending through engine 10, and compressed air is supplied to high pressure compressor 14. The highly compressed air is delivered to combustor 16. Airflow (not shown in
Stationary stator member 102 of seal assembly 100 is a stationary member that extends circumferentially around the axis of rotation 34 of gas turbine engine 10. The stator is comprised of a base 112 and a flange member 109. The base includes a base sealing surface 90 and a stop surface 113. The flange and base are perpendicular. As shown in
Seal assembly 100 also is comprised of moveable stator member 110 includes a sealing face 124 and a plurality of sealing teeth 127, 128 that extend outward from a portion of the sealing face 124. The stator 110 is movable axially, in direction generally represented by direction arrow 200 in
Moveable stator member 110 also includes an opening 135 defined therein. The opening extends in the axial direction 200 when the movable stator is correctly coupled with flange 108. As shown in
In the exemplary embodiment, openings 135 are oriented substantially perpendicular to rotating member surface 125. As described below in more detail, openings 135 help to prevent contact between the movable member 110, and specifically the plurality of teeth 127, 128; and rotating member 104. The movable stator may include any number of openings 135 but for purposes of disclosing the exemplary embodiment, one or more openings 135 may be included in movable stator 110. Moveable stator member 110 further includes at least one radially extending opening 134. For purposes of disclosing the exemplary embodiment, a plurality of openings 134 are illustrated. However, any suitable number of radial openings 134 may be provided in stator 110. The opening 134 extends through surfaces 119 and 121 of the moveable stator member 110. In the exemplary embodiment, each opening 135 is located adjacent openings 134.
Moveable stator member 110 also includes yoke 130. The yoke extends radially and defines an opening 131 that receives a seal member 132. The seal member may be made from any suitable sealing material. As shown in
Seal assembly 100 also comprises at least one flexure member 150. The flexure member is substantially flat. As assembled, one end of flexure member is located proximate the flange member 109. This end is identified as 157 in
The flexure member 150 comprises a weak spring which flexes out of plane to allow axial translation of the moveable stator member 110 relative to the stationary stator member 102. The connection of the flexure member 150 to the moveable stator member 110 is shown in these figures for simplicity as being bolted to the frame 103, but integral with the moveable stator 110. It could alternatively be a separate piece, but such a configuration may increase weight, complexity, and part count.
The flexure member 150 serves as a biasing mechanism for moving the moveable stator member 110. The member 150 biases the movable stator member toward the first position of
As shown in
The seams 160 are openings within each flexure member 150 that have been cut therein into a pattern determined beforehand as suitable to enable the flexure member 150 to flex and therefore bias as required. A suitable method for cutting the seams 160 into the flexure member 150 is by electro discharge machining which process is well known by persons of skill in the art. It is noted herein, though, that the methodology for cutting the seams 160 into the flexure member 150 forms no part of the invention herein. In another embodiment herein, a flexure member 150 may be cast such that the seams 160 are a by-product of the casting process; i.e., cast such that the openings are part of the process. Additionally, stress relief holes 161 may be added at the ends of the cut-out portions of the seams 160, for example, as shown in
The flexure members 150 always act to open the seal (moving the movable stator member 110 to the position shown in
As shown in
During operation, cooling air and/or fluids flow through gas turbine engine 10. When engine 10 is in operation, high pressure air flows toward the aft engine end 29. A portion of the highly compressed air discharged from high pressure compressor 14 is directed towards seal assembly 100 for use as cooling fluid. Seal assembly 100 facilitates substantially controlling fluid flow from a region of higher pressure 137 to a region of lower pressure 140 within gas turbine engine 10. The pressure differential between higher pressure region 137 and lower pressure region 140 initiates flow through seal assembly 100. The pressures acting on the moveable stator member 110 are such that the pressure forces overcome the spring force of the flexure member 151, and the moveable stator member 110 will translate from the first position (shown in
Additionally, during operation, a portion of the high pressure air flows through openings 135. In the exemplary embodiment, opening 135 is a plurality of feed openings. Openings 135 form a high pressure film or air bearing between surfaces 124 and rotating member surface 125. The air bearing prevents moveable stator member 110 from contacting rotating member 104.
After air flows through opening 135, the air exits to the region of lower pressure 140. Also, a portion of air may leak past seal teeth 126, 127, 128. Air that leaks past seal teeth 126, 127, 128 and that portion of the air that has exited opening 135 and flows radially outward, flows through radial openings 134 to the region of lower pressure 140.
While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.
Claims
1. A seal assembly comprising:
- a first movable stator member movable between a sealing position and a non-sealing position, a second fixed stator member, the first stator member being movable relative to the second stator member, the seal assembly further comprising at least one flexure member coupled to the second stator member, and at least one biasing member coupled between the at least one flexure member and the movable stator for biasing the movable stator to a non-sealing position.
2. The seal assembly of claim 1 having at least two flexure members and two biasing members, each biasing member coupled to a flexure member.
3. The seal assembly as claimed in claim 1, the second stator comprising a base and a surface along the base, the first stator comprising a sealing member that sealingly engages the contact surface of said base.
4. The seal assembly of claim 3 wherein the first stator comprises a yoke, said member being located in said yoke.
5. The seal assembly as claimed in claim 1 wherein the flexure member is supported on a fastener member.
6. The seal assembly of claim 1, wherein said flexure member includes at least one seam which permits said flexure member to flex out of plane.
7. The seal assembly of claim 6, wherein said seam comprises an opening through said flexure member.
8. The seal assembly of claim 7, wherein said flexure member includes a plurality of seams, said seams defining at least one beam therebetween, said beam being connected to another beam at their proximate ends.
9. The seal assembly of claim 8, wherein said flexure member includes at least one stress relief hole at the end of a seam.
10. A seal assembly comprising:
- a first movable stator member movable between a sealing position and a non-sealing position, a second fixed stator member, the first stator member being movable relative to the second stator member, the seal assembly further comprising at least one flexure member coupled to the second stator member, and at least one biasing member coupled between the at least one flexure member and the movable stator for biasing the movable stator to a non-sealing position, said flexure member including at least one seam which permits said flexure member to flex out of plane, said flexure member includes a plurality of seams, said seams comprising openings through said flexure member and defining at least one beam therebetween, said beam being connected to another beam at their proximate ends, and said flexure member including at least one stress relief hole at the end of a seam.
Type: Application
Filed: Jul 11, 2008
Publication Date: Sep 22, 2011
Inventors: Kripa Varanasi (Lexington, MA), Joseph Albers (Wright, NY), William Lee Herron (Cincinnati, OH), Peter Crudgington (Freshford Bath), Mahesh Khandeparker (Karnataka), Sai Raju Ippili (Karnataka), Prathap Anga (Karnataka), Cheryl Herron (Cincinnati, OH)
Application Number: 12/171,418
International Classification: F01D 25/16 (20060101);