LIGHTWEIGHT TIE ROD FOR A GAS TURBINE

Description

FIELD OF THE INVENTION

[0001] The present invention relates to assembly systems and methods, and more particularly, to assembly systems and methods in gas turbine engines.BACKGROUND OF THE DISCLOSURE

[0002] Gas turbine engines typically comprise tierods to provide structural support for various components of the gas turbine engine. In aircraft having smaller sized engines, the loss of volume can negatively impact the engine design and performance. For example, the loss of volume can result in less volume available for other cooling fluid to circulate.

[0003] US 8511969 B2 relates to a gas turbine engine with a mid turbine frame disposed between turbine rotor assemblies. The mid turbine frame includes hollow airfoils radially extending through an annular gas path duct. The airfoils each include a double-walled leading edge structure to define a front chamber separated from a rear chamber defined in the remaining space within the airfoil. US 2015 / 345337 A1 relates to a turbine housing section including a radially inner case centered on a first axis, and a radially outer case spaced radially outwardly of the inner case, and centered on a second axis. The first and second axes are offset relative to each other. A plurality of tie rods include a threaded nut received on a tie rod, with the plurality of tie rods connecting the inner and outer cases. The plurality of tie rods are spaced circumferentially about both of the first and second axes, and extend for distinct lengths between the inner and outer cases such that the inner and outer cases are held at a position wherein the first and second axes are offset.SUMMARY OF THE INVENTION

[0004] According to a first aspect, there is provided an assembly for a gas turbine engine according to claim 1.

[0005] The tierod may comprise a base comprising the base flange, a rod extending from the base, and a head opposite the base and extending from the rod. The bearing mounting ring may comprise at least one aperture for receiving the tierod. The joint may be configured to increase a volume of a bearing compartment on an inner surface of the bearing mounting ring. The joint may couple an outer surface of the base flange to the inner surface of the bearing mounting ring. The rod may extend through an aerodynamic fairing. The head may be configured to be mechanically coupled to an annular outer structure. A coefficient of thermal expansion of the bearing mounting ring may be substantially the same as the coefficient of thermal expansion of the tierod. The joint may be configured to decrease a thickness of the base flange. The tierod may comprise a cast nickel alloy.

[0006] From a further aspect of the invention, a gas turbine engine as claimed in claim 8 may be provided.

[0007] The tierod may comprise a base comprising the flange, a rod extending from the base, and a head opposite the base and extending from the rod. The tierod may extend radially from the bearing mounting ring, through the fairing structure, to the annular outer structure. The head of the tierod may be configured to be mechanically coupled to the annular outer structure. A coefficient of thermal expansion of the tierod may be the same as a coefficient of thermal expansion of the bearing mounting ring. Brazing the tierod to the bearing mounting ring may be configured to increase a volume of a bearing compartment.

[0008] According to a further aspect of the disclosure there is provided a method as claimed in claim 11 of assembling an assembly of a gas turbine engine.

[0009] The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in, and constitute a part of, this specification, illustrate various embodiments, and together with the description, serve to explain the principles of the disclosure. FIG. 1 illustrates a cross-sectional view of a gas turbine engine in accordance with various embodiments; FIGS. 2a, 2b, and 2c illustrate a perspective, cross-sectional, and axial view, respectively, of the assembly in accordance with various embodiments; FIG. 3 illustrates an expanded cross-sectional view of the assembly in accordance with various embodiments; FIG. 4 illustrates an expanded cross-sectional view the assembly of FIG. 3 in accordance with various embodiments; and FIG. 5 depicts a flowchart illustrating a method of assembling an assembly of a gas turbine engine in accordance with various embodiments. DETAILED DESCRIPTION

[0011] The detailed description of various embodiments herein makes reference to the accompanying drawings, which show various embodiments by way of illustration. While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that logical, chemical, electrical, and mechanical changes may be made without departing from the scope of the disclosure. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation.

[0012] For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected, or the like may include permanent, removable, temporary, partial, full, and / or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact.

[0013] For example, in the context of the present disclosure, methods, systems, and articles may find particular use in connection with gas turbine engines. However, various aspects of the disclosed embodiments may be adapted for optimized performance in a variety of engines or other systems. As such, numerous applications of the present disclosure may be realized.

[0014] Referring to FIG. 1, a gas turbine engine 100 (such as a turbofan gas turbine engine) is illustrated according to various embodiments. Gas turbine engine 100 is disposed about axial centerline axis 120, which may also be referred to as axis of rotation 120. Gas turbine engine 100 may comprise a fan 140, compressor sections 150 and 160, a combustion section 180, and turbine sections 190, 191. The fan 140 may drive air into compressor sections 150, 160, which further drive air along a core flow path for compression and communication into the combustion section 180. Air compressed in the compressor sections 150, 160 may be mixed with fuel and burned in combustion section 180 and expanded across the turbine sections 190, 191. The turbine sections 190, 191 may include high pressure rotors 192 and low pressure rotors 194, which rotate in response to the expansion. The turbine sections 190, 191 may comprise alternating rows of rotary airfoils or blades 196 and static airfoils or vanes 198. Cooling air may be supplied to the turbine sections 190, 191 from the compressor sections 150, 160. A plurality of bearings 115 may support spools in the gas turbine engine 100. FIG. 1 provides a general understanding of the sections in a gas turbine engine, and is not intended to limit the disclosure. The present disclosure may extend to all types of applications and to all types of turbine engines, including turbofan gas turbine engines and turbojet engines.

[0015] Referring to FIGs. 2a-2c, according to various embodiments, a schematic diagram of an assembly 200 for gas turbine engine 100 is depicted. Assembly 200 may be situated in a midturbine frame situated between turbine sections 190 and 191 of gas turbine engine 100. With reference to FIG. 2a, assembly 200 may be disposed about axial centerline axis 120 of gas turbine engine 100.

[0016] Referring now to FIGs. 2b and 2c, FIG. 2b depicts a cross-sectional view of assembly 200 along section line 3-3. FIG. 2c depicts an axial view of assembly 200. Assembly 200 may comprise tierod 210, fairing structure 230, bearing mounting ring 250, and annular outer structure 270. Fairing structure 230 may comprise a plurality of aerodynamic fairings 231 extending radially within fairing structure 230. The aerodynamic fairings 231 of fairing structure 230 may comprise an aperture 232 configured to receive tierod 210. Tierod 210 may extend radially from bearing mounting ring 250 to annular outer structure 270. As will be discussed in further detail with reference to FIG. 3 and FIG. 4, tierod 210 is brazed to bearing mounting ring 250 and mechanically coupled to annular outer structure 270. Bearing mounting ring 250 comprises bearing compartment 252 on its inner surface.

[0017] With reference now to FIG. 3, assembly 200 is depicted in greater detail. Tierod 210 may comprise a base 211 comprising a base flange 212. Base flange 212 may extend around an outer portion of base 211, comprising a relatively wider surface area than base 211. The base flange 212 may be integral with base 211. In various embodiments, base flange 212 may be coupled to base 211 by other methods, including but not limited to welding, brazing, and / or sintering. Base flange 212 comprises an outer surface 213 configured to be brazed to an inner surface 251 of the bearing mounting ring 250. Tierod 210 may further comprise a rod 214 extending from the base 211 and a head 215 extending from the rod 214 and opposite the base 211. In various embodiments, base 211, rod 214, and head 215 may be integral with each other. In various embodiments, base 211, rod 214, and head 215 may be separate components coupled together.

[0018] Tierod 210 extends through fairing structure 230 and may be coupled to the bearing mounting ring 250 and annular outer structure 270. For example, tierod 210 may extend through fairing structure 230 and coupled to annular outer structure 270 utilizing a mechanical coupling. Outer surface 213 of the flange 212 is brazed to inner surface 251 of bearing mounting ring 250. Outer surface 213 and inner surface 251 may be brazed throughout an entirety of their mating surfaces or a portion of their mating surfaces.

[0019] Tierod 210 and bearing mounting ring 250 may be the same or similar materials. For example, tierod 210 and bearing mounting ring 250 may be a cast nickel alloy, a nickel chromium alloy (such as that sold under the mark INCONEL, e.g., INCONEL 600, 617, 625, 718, X-70, and the like) and / or the like. Tierod 210 and bearing mounting ring 250 may have a substantially similar coefficient of thermal expansion (CTE). For example, a CTE of tierod 210 may be within + / - 10% of a CTE of bearing mounting ring 250. Tierod 210 and bearing mounting ring 250 comprising materials with substantially similar CTEs allows tierod 210 and bearing mounting ring 250 to expand at similar rates in response to changes in temperature, thereby making structural failure of joints 290 and assembly 200 less likely.

[0020] With reference now to FIG. 4, joints 290 are shown connecting outer surface 213 of flange 212 and inner surface 251 of bearing mounting ring 250. Joints 290 may result from various brazing processes, including but limited to torch brazing, furnace brazing, silver brazing, braze welding, cast iron welding brazing, vacuum brazing, dip brazing, or other brazing techniques. Various materials may be used for brazing of joints 290, including but not limited to nickelboron pastes, nickel-silicon pastes, nickel-phosphorus pastes, gold pastes or other any other material capable of withstanding high temperatures in the gas turbine engine 100. While joints 290 are shown only between a portion of outer surface 213 and inner surface 251 on flange 212 in FIG. 4, joints 290 are not limited in this regard. Alternative embodiments of assembly 200 may comprise one joint 290 extending an entire length of a mating surface between outer surface 213 and inner surface 251, for example. In this regard, base 211 may be a separate component from rod 214 and joint 290 may couple base 211 to rod 214 and bearing mounting ring 250. Further embodiments may comprise multiple joints 290 along the entire length of the mating surface between outer surface 213 and inner surface 251.

[0021] Brazing tierod 210 to bearing mounting ring 250 results in numerous advantages. In this regard, assembly 200 utilizing joints 290 between tierod 210 and bearing mounting ring 250 can limit additional weight to gas turbine engine 100 and limit the occupied space in bearing compartment 252 by reducing a thickness of the flange 212. This allows bearing compartment 252 to better accommodate oil routing components and cooling applications such as oil scavenging, for example. Additional space in bearing compartment 252 can be seen in FIG. 3 and FIG 4. as indicated by shaded region 254.

[0022] A block diagram illustrating a method 500 for assembling a assembly, such as assembly 200, is depicted in FIG. 5, in accordance with various embodiments. Method 500 comprises positioning a fairing structure within an annular outer structure. Method 500 further comprises inserting a tierod through a bearing mounting ring. The method further comprises inserting the tierod through the fairing structure. The method further comprises coupling the tierod to the annular outer structure and brazing the tierod to the bearing mounting ring. Method 500 is not intended to be limited in this regard. For example, in various embodiments, method 500 may comprise brazing the tierod to the bearing mounting ring prior to coupling the tierod to the annular outer structure.

[0023] Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and / or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure. The scope of the disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more." Moreover, where a phrase similar to "at least one of A, B, or C" is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Different crosshatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials.

[0024] Methods, systems, and computer-readable media are provided herein. In the detailed description herein, references to "one embodiment", "an embodiment", "various embodiments", etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.

[0025] As used herein, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Claims

1. An assembly (200) for a gas turbine engine (100), comprising: a tierod (210); wherein the tierod (210) comprises a base flange (212), the assembly further comprising: a brazed joint (290), a fairing structure (230) positioned within an annular outer structure (270); and a bearing mounting ring (250) defining a bearing compartment (252) on its inner surface, wherein the brazed joint is located between mating surfaces of the tierod base flange (212) and the bearing mounting ring (250), wherein the tierod extends through the bearing mounting ring and the fairing structure, wherein the brazed joint (290) is between an outer surface (213) of the base flange (212) and an inner surface (251) of the bearing mounting ring (250) that defines a boundary of the bearing compartment (252).

2. The assembly (200) of claim 1, wherein the tierod (210) comprises a base (211) comprising the base flange (212), a rod (214) extending from the base (211), and a head (215) opposite the base (211) and extending from the rod (214).

3. The assembly (200) of claim 1 or 2, wherein the bearing mounting ring (250) comprises at least one aperture for receiving the tierod (210).

4. The assembly (200) of claim 3, wherein the joint (290) couples an outer surface (213) of the base flange (212) to the inner surface (251) of the bearing mounting ring (250).

5. The assembly (200) of any of claims 3 to 4, wherein the rod (214) extends through an aerodynamic fairing (230).

6. The assembly (200) of any of claims 3 to 5, wherein the head (215) is configured to be mechanically coupled to an annular outer structure (270).

7. The assembly (200) of any preceding claim, wherein the tierod (210) comprises a cast nickel alloy.

8. A gas turbine engine (100), comprising: the assembly (200) according to any preceding claim, wherein the fairing structure (230) comprises a plurality of aerodynamic fairings (231).

9. The gas turbine engine (100) of claim 8, wherein the tierod (210) extends radially from the bearing mounting ring (250), through the fairing structure (230), to the annular outer structure (270).

10. The assembly of any of claims 1 to 7 or the gas turbine engine (100) of any of claims 8 to 9, wherein a coefficient of thermal expansion of the bearing mounting ring (250) is substantially the same as a coefficient of thermal expansion of the tierod (210).

11. A method of assembling an assembly (200) of a gas turbine engine (100), comprising: positioning a fairing structure (230) within an annular outer structure (270); inserting a tierod (210) through a bearing mounting ring (250), the tierod comprising a base flange comprising an outer surface (213) and the bearing mounting ring comprising an inner surface (251) defining a bearing compartment (252); inserting the tierod (210) through the fairing structure (230); coupling the tierod (210) to the annular outer structure (270); and coupling the outer surface of the base flange of the tierod (210) to the inner surface of the bearing mounting ring (250), wherein the step of coupling the tierod (210) to the bearing mounting ring (250) utilizes a brazing joint (290) that is located between the outer surface of the base flange and the inner surface of the bearing mounting ring.