Additive manufacturing bearing cover for temperature reduction on bearing cover wet

Abstract

In conventional bearing caps, the temperature of an oil-wetted surface defining an oil sump may be subjected to high temperatures, which may lead to oil degradation, paint film and coking. Thus, a bearing cap (300) is disclosed that reduces the temperature experienced by the oil-wetted surface (420). In particular, the bearing cap (300) may include one or more air-insulated cavities (430) between a surface (410) exposed to heated air and an oil-wetted surface (420) defining an oil sump (425) to provide a thermal barrier between the two surfaces.

Description

TECHNICAL FIELD

[0001] The embodiments described herein relate generally to gas turbine engines, and more particularly, to an additively manufactured bearing cover in a gas turbine engine that reduces temperature on an oil wetted wall. BACKGROUND

[0002] Gas turbine engines include a series of bearings along their length to minimize friction and ensure smooth rotation of the shaft. These bearings are typically housed within a bearing cover. The bearing cover typically forms a boundary that encloses oil, which forms an oil sump that serves as a reservoir for lubricating oil from downstream bearings and provides lubrication to reduce friction and cooling to prevent overheating. Thus, each bearing cover can include an oil wetted wall surface on one side of the bearing cover.

[0003] The oil wetted wall surface can be subjected to temperatures in excess of 400 degrees Fahrenheit. Such high temperatures can cause oil degradation, paint film, and coking. This in turn can cause oil drain port plugging. In extreme cases, oil degradation can cause a fire.

[0004] The present disclosure is directed to overcoming this and other issues discovered by the inventors. SUMMARY

[0005] In an embodiment, a bearing cover for a gas turbine engine, the bearing cover comprising: a first surface on a first side, wherein the first surface is annular about a longitudinal axis; a second surface on a second side opposite the first side and downstream of the first side, wherein the second surface is annular about the longitudinal axis; and one or more air isolation cavities between the first surface and the second surface, wherein each of the one or more air isolation cavities is annular about the longitudinal axis.

[0006] In an embodiment, a method of manufacturing a bearing cap, the method comprising: printing the bearing cap using additive manufacturing in layers such that the bearing cap comprises: a first surface on a first side, wherein the first surface is annular about a longitudinal axis; a second surface on a second side opposite the first side and downstream of the first side, wherein the second surface is annular about the longitudinal axis; at least one air insulation cavity between the first surface and the second surface, wherein the at least one air insulation cavity is annular about the longitudinal axis; and one or more powder removal holes extending from one or both of a radially innermost end of the at least one air insulation cavity or a radially outermost end of the at least one air insulation cavity to an external environment of the bearing cap, wherein, in a cross-sectional plane comprising the longitudinal axis, a radially outer first portion of the at least one air insulation cavity extends away from the longitudinal axis and towards the second side at a first angle relative to the longitudinal axis, a radially inner second portion of the at least one air insulation cavity extends away from the longitudinal axis and towards the first side at a second angle relative to the longitudinal axis, and one or both of the radially innermost end of the at least one air insulation cavity or the radially outermost end of the at least one air insulation cavity has a teardrop shape; and sealing the one or more powder removal holes.

[0007] In an embodiment, a bearing cap for a gas turbine engine, the bearing cap comprising: a first surface on a first side, wherein the first surface is annular about a longitudinal axis; a second surface on a second side opposite the first side and downstream of the first side, wherein the second surface is annular about the longitudinal axis and defines an oil sump on the second side; and a plurality of air insulation cavities between the first surface and the second surface, wherein each of the plurality of air insulation cavities is annular about the longitudinal axis, and wherein the plurality of air insulation cavities comprises: a first air insulation cavity comprising, in a cross-sectional plane comprising the longitudinal axis, a radially outer first portion extending away from the longitudinal axis and towards the second side at a first non-zero angle relative to the longitudinal axis, and a radially inner second portion extending away from the longitudinal axis and towards the first side at a second non-zero angle relative to the longitudinal axis, wherein a profile of the first air insulation cavity matches a profile of the oil sump; and a second air insulation cavity downstream of a radially innermost end of the first air insulation cavity. BRIEF DESCRIPTION OF DRAWINGS

[0008] The details of an embodiment of the present disclosure, both as to its structure and operation, can be gleaned in part by studying the accompanying drawings, in which like reference numerals refer to like parts, and in which:

[0009] Figure 1 A schematic diagram of a gas turbine engine according to an embodiment is shown;

[0010] Figure 2 A cross-sectional view of a bearing cover assembly according to an embodiment is shown;

[0011] Figure 3 A perspective view of the bearing cover according to an embodiment is shown;

[0012] Figure 4A and 4B Cross-sectional views of the bearing cap according to an embodiment in two different cross-sectional planes are shown;

[0013] Figures 5A-5C A perspective cross-sectional view of a portion of the bearing cover according to an alternative embodiment is shown;

[0014] Figure 6A and 6B The placement of the powder removal hole according to an alternative embodiment is shown in a perspective cross-sectional view of the bearing cap section; and

[0015] Figure 7 An air-insulating cavity within a bearing cover according to an embodiment is shown.

[0016] Figure 8 An additive manufacturing process for manufacturing a bearing cap according to an embodiment is shown. Detailed Implementation

[0017] The detailed description set forth below with reference to the accompanying drawings is intended to describe various embodiments and is not intended to represent the only embodiments that can be practiced with respect to this disclosure. The detailed description includes specific details in order to provide a thorough understanding of the embodiments. However, it will be apparent to those skilled in the art that embodiments of the invention can be practiced without these specific details. In some instances, well-known structures and components are shown in simplified form for the purpose of brevity. Furthermore, it should be understood that the various components shown herein are not necessarily drawn to scale. In other words, features disclosed in the various embodiments may be implemented using relative dimensions within and between components that differ from those shown in the accompanying drawings.

[0018] Figure 1 A schematic diagram of a gas turbine engine 100 according to an embodiment is shown. The gas turbine engine 100 includes a shaft 102 having a central longitudinal axis L. A number of other components of the gas turbine engine 100 are concentric with the longitudinal axis L and may be arranged in a ring around the longitudinal axis L. The radial axis may refer to any axis or direction radiating outward from the longitudinal axis L at an angle substantially orthogonal to the longitudinal axis L, for example... Figure 1The term "radially outward" shall be understood to mean further away or away from the longitudinal axis L, and the term "radially inward" shall be understood to mean closer to or toward the longitudinal axis L. As used herein, the term "radial" will refer to any axis or direction that is generally perpendicular to the longitudinal axis L, and the term "axial" will refer to any axis or direction that is generally parallel to the longitudinal axis L.

[0019] In embodiments, the gas turbine engine 100 includes, from an upstream end to a downstream end, an inlet 110, a compressor 120, a combustor 130, a turbine 140, and an exhaust outlet 150. Additionally, the downstream end of the gas turbine engine 100 can include a power take-off coupling 104. One or more of these components of the gas turbine engine 100, including potentially all of these components, can be made of stainless steel and / or a durable high-temperature material known as a "superalloy." A superalloy is an alloy that, at high temperatures, exhibits excellent mechanical strength and creep resistance, good surface stability, and resistance to corrosion and oxidation. Examples of superalloys include, but are not limited to, Hastelloy, Inconel, Waspaloy, Rene alloys, Haynes alloys, Incoloy, MP98T, TMS alloys, and CMSX single crystal alloys.

[0020] The inlet 110 can collect the working fluid F into an annular flow path 112 about the longitudinal axis L. The working fluid F flows into the compressor 120 through the inlet 110. While the working fluid F is shown flowing into the inlet 110 from a particular direction at an angle that is substantially normal to the longitudinal axis L, it shall be understood that the inlet 110 can be configured to receive the working fluid F from any direction at any angle that is suitable for the particular application of the gas turbine engine 100. While the working fluid F will be primarily described herein as air, it shall be understood that the working fluid F can include other fluids, including other gases.

[0021] The compressor 120 can include a series of compressor rotor assemblies 122 and stator assemblies 124. Each compressor rotor assembly 122 can include a rotor disk that is circumferentially populated with a plurality of rotor blades. The rotor blades in a rotor disk are separated from the rotor blades in an adjacent disk along an axial axis by a stator assembly 124. The compressor 120 compresses the working fluid F through a series of stages corresponding to each compressor rotor assembly 122. The compressed working fluid F then flows from the compressor 120 into the combustor 130.

[0022] The combustor 130 can include a combustor shell 132 that houses one or more, typically a plurality, of fuel injectors 134. In embodiments having a plurality of fuel injectors 134, the fuel injectors 134 can be arranged circumferentially within the combustor shell 132 about the longitudinal axis L at equal intervals. The combustor shell 132 diffuses the working fluid F, and the fuel injector(s) 134 injects fuel into the working fluid F. This injected fuel is ignited to produce a combustion reaction in one or more combustion chambers 136. The products of the combustion reaction drive the turbine 140.

[0023] The turbine 140 can include one or more turbine rotor assemblies 142 and stator assemblies 144 (e.g., nozzles). Each turbine rotor assembly 142 can correspond to one of a plurality or series of stages. The turbine 140 extracts energy from the combusted fuel-gas mixture as it passes through each stage. The energy extracted by the turbine 140 can be transferred (e.g., to an external system) via the power output coupling 104, and to the compressor 120 via the shaft 102.

[0024] Exhaust E from the turbine 140 can flow into an exhaust outlet 150. The exhaust outlet 150 can include an exhaust diffuser 152 that diffuses the exhaust E, and an exhaust collector 154 that collects, redirects, and outputs the exhaust E. It should be understood that the exhaust E output by the exhaust collector 154 can be further processed, for example, to reduce harmful emissions, recover heat, etc. Additionally, while the exhaust E is shown flowing out of the exhaust outlet 150 in a particular direction at an angle that is substantially orthogonal to the longitudinal axis L, it should be understood that the exhaust outlet 150 can be configured to output the exhaust E toward any direction and at any angle suitable for the particular application of the gas turbine engine 100.

[0025] Figure 2 A cross-sectional view of a bearing assembly 200 according to an embodiment is shown. The bearing assembly 200 can be positioned between the compressor 120 and the combustor 130. The bearing assembly 200 can include a bearing cover shroud 210, a bearing cover 300 downstream of and secured to the bearing cover shroud 210, and a bearing system 220 downstream of and secured to the bearing cover 300. The bearing system 220 includes a bearing 225 that provides radial support for the shaft 102. The bearing cover shroud 210, the bearing cover 300, and the bearing system 220 all encircle the longitudinal axis L of the gas turbine engine 100 so as to encircle the shaft 102 at a downstream end of the compressor 120. It should be understood that the bearing assembly 200 is shown separately, and in practice, the bearing assembly 200 will interface with other components of the gas turbine engine 100.

[0026] The bearing cap shroud 210 protects the bearing cap 300. In particular, the bearing cap shroud 210 provides physical protection for the bearing cap 300 and the bearing system 220. The bearing cap shroud 210 acts as a barrier to prevent foreign matter, such as dust, dirt, or debris, from entering the bearing system 220. By excluding these contaminants, the bearing cap shroud 210 helps to maintain the integrity and performance of the bearing system 220. Additionally, the bearing cap shroud 210 can provide thermal insulation for the bearings 225. The gas turbine engine 100 can operate at high temperatures, and the bearings 225 can be subjected to heat generated by surrounding components. The bearing cap shroud 210 can help to minimize the transfer of heat to the bearings 225, thereby protecting them from excessive thermal stress and ensuring their longevity. Furthermore, the bearing cap shroud 210 can act as a barrier to reduce the transmission of noise and vibration from the compressor 120 to downstream components, thereby helping to create a quieter environment.

[0027] The bearing assembly 200 can include an air seal 230 between the bearing cap shroud 210 and the shaft 102. In particular, the air seal 230 can extend annularly around the shaft 102 between an outer diameter of the shaft 102 and an inner diameter of the bearing cap shroud 210. The air seal 230 prevents air from the compressor 120 from leaking downstream through the bearing cap shroud 210.

[0028] The bearing cap assembly 200 can include an oil seal 240 between the bearing cap 300 and the shaft 102. In particular, the oil seal 240 can extend annularly around the shaft 102 between an outer diameter of the shaft 102 and an inner diameter of the bearing cap 300. The oil seal 240 prevents lubricating oil from the bearings 225 from leaking upstream through the bearing cap 300. In other words, the oil seal 240 ensures that oil remains within a chamber surrounding the bearings 225. This oil helps to reduce friction, minimize wear, and dissipate heat generated during operation.

[0029] More generally, the bearing cap assembly 200 can include one or more seal rings, including one or more of the air seal 230 and / or the oil seal 240. Each seal ring can encircle a central passage through the bearing cap 300, through which the shaft 102 extends. These seal rings prevent fluid (e.g., air, oil, etc.) from leaking from one side of the bearing cap 300 to the other side of the bearing cap 300.

[0030] The bearing cap 300 can prevent unwanted particles from entering the bearing system 220, thereby ensuring proper alignment and smooth operation of the bearing 225. In particular, the bearing cap 300 provides a shell that protects the bearing 225 from external elements such as dust, dirt, and debris that can be harmful to the performance and longevity of the bearing. Additionally, the bearing cap 300 can generally form a boundary that encloses oil, which forms an oil pool 425 that serves as a reservoir for lubricating oil, thereby allowing for a controlled supply of lubricating oil to the bearing 225, reducing friction, and minimizing wear due to high temperatures. The bearing cap 300 can be made of a nickel alloy, such as Alloy-X, Alloy-718, 17-4PH stainless steel, or the like.

[0031] Figure 3 A perspective view of a bearing cap 300 according to an embodiment is shown. Each bearing cap 300 can include, in order from an upstream end to a downstream end, a main body 310, a tapered portion 320, and a flange 330. Each of these components is annular about a longitudinal axis L. Additionally, the bearing cap 300 can include one or more, and preferably a plurality, of stiffeners 315 arranged at equidistant intervals about the longitudinal axis L.

[0032] The main body 310 is generally cylindrical. In the illustrated embodiment, the air seal 230 and the oil seal 240 are positioned on a radially inward-facing surface of the main body 310, with the oil seal 240 downstream of the air seal 230.

[0033] The tapered portion 320 is generally conical. The tapered portion 320 extends downstream and tapers radially outward from the downstream end of the main body 310.

[0034] Each stiffener 315 can extend from a radially outward-facing surface of the main body 310 to a radially outward-facing surface of the tapered portion 320 to stiffen the interface between the two components. In particular, the stiffeners 315 provide stiffening to enhance the stiffness and strength of the bearing cap 300. The stiffeners 315 can be secondary plates or segments that stiffen the tapered portion 320 against out-of-plane deformation. The stiffeners 315 can be connected to the main body 310 and the tapered portion 320 by welding or other means, or can be additively manufactured with the other components of the bearing cap 300.

[0035] The flange 330 is generally disc-shaped. The flange 330 extends radially outward from the downstream end of the tapered portion 320. The flange 330 can include a plurality of axial apertures arranged at equidistant intervals about the longitudinal axis L. Each aperture can be configured to enable a bolt or other fastener to be inserted therethrough. The flange 330 enables the bearing cap 300 to be bolted to another component of the gas turbine engine 100 that is downstream of the bearing cap 300.

[0036] Figure 4AA cross-sectional view of the bearing cover 300 in a first cross-sectional plane is shown, according to an embodiment. It should be appreciated that this cross-sectional plane includes the longitudinal axis L. The bearing cover 300 includes a first surface 410 on a first side, and a second surface 420 on a second side opposite the first side. It is contemplated that the first side is an upstream side of the bearing cover 300, such that the first surface 410 is exposed to working fluid F (e.g., air) output by the compressor 120, while the second side is a downstream side of the bearing cover 300, such that the second surface 420 is wetted by lubricating oil used for the bearing 225. The first surface 410 is heated by the working fluid F. This heat will typically be transferred via conduction through the body 310 and / or the tapered portion 320 toward the second surface 420.

[0037] In embodiments, the second surface 420 defines an oil sump 425. The oil sump 425 is a cavity or recess that serves as a reservoir for lubricating oil from the downstream bearing 225 to cool before exiting through the drain. In practice, the oil sump 425 will contain lubricating oil from the downstream bearing 225. Thus, the second surface 420 will be wetted by oil, and can help to cool the bearing cover 300 during operation of the gas turbine engine 100.

[0038] The bearing cover 300 can include one or more air isolation cavities 430, shown as a first air isolation cavity 430A and a second air isolation cavity 430B. In alternative embodiments, the bearing cover 300 can consist of only a single air isolation cavity 430 (e.g., 430A or 430B) or three or more air isolation cavities 430. The number of air isolation cavities 430 can depend on the manufacturing process of the bearing cover 300, the shape and / or size of the bearing cover 300, and / or other design considerations. For example, the first air isolation cavity 430A and the second air isolation cavity 430B can alternatively be joined into a single air isolation cavity 430. However, this can create too much stress in the single air isolation cavity 430. Thus, in the illustrated embodiment, the air isolation cavities 430 have been split into the first air isolation cavity 430A and the second air isolation cavity 430B to reduce the total stress from the air isolation feature.

[0039] Each air-insulating cavity 430 provides a thermal barrier that reduces heat transfer from one side of the bearing cap 300 to the opposite side of the bearing cap 300 (including from the first surface 410 to the second surface 420). Specifically, heat transfer to the oil sump 425 is reduced. Additionally, each air-insulating cavity 430 reduces the mass and weight of the bearing cap 300. One or more air-insulating cavities 430 may be formed to substantially match the contours of the first surface 410 and / or the second surface 420. The thickness of each air-insulating cavity 430 can be selected such that the reduction in heat transfer provided by a thicker air-insulating cavity 430 (e.g., at least 0.05 inches thick) is balanced with the structural integrity of the walls between the first surface 410 and the air-insulating cavity 430, and between the second surface 420 and the air-insulating cavity 430, such that these walls remain structurally intact (e.g., at least 0.2 inches thick). In embodiments where additive manufacturing is used to construct the bearing cap 300, the thickness of each air-insulating cavity 430 should also be sufficient to allow powder removal from the air-insulating cavity 430. The thickness of the first wall between the first surface 410 and the air-insulating cavity 430 and the thickness of the second wall between the second surface 420 can be the same. Alternatively, the thicknesses of the first wall and the second wall can be different. For example, the first wall can be thicker to reinforce the first surface 410 and reduce volumetric stress on the first surface 410.

[0040] The bearing cap 300 may include a mixing air chamber 440 that captures the pressure compressor discharge (PCD) from the compressor 120. The mixing air chamber 440, which may be upstream of one or more air-insulating chambers 430, may be annular about a longitudinal axis L. The mixing air chamber 440 is in fluid communication with a mixing air passage 450. The working fluid F in the mixing air chamber 440 flows through the mixing air passage 450 to a system that buffers the working fluid F for the turbine 140. For example, the working fluid F may be used to cool components of the turbine 140, for example, by creating a barrier of cooler air around hot components such as turbine blades or combustor bushings.

[0041] Figure 4B A cross-sectional view of the bearing cap 300 according to an embodiment is shown in a second cross-sectional plane. Specifically, Figure 4B The cross-sectional plane shown is relative to Figure 4A The cross-sectional plane shown is rotated 90 degrees about the longitudinal axis L. As shown in this view, the bearing cap 300 may include a buffer air passage 460. The buffer air passage 460 may be in fluid communication with other components of the gas turbine engine 100, such as the oil seal 240, that buffer the cooled working fluid F from the compressor 120 to other components of the gas turbine engine 100.

[0042] Figure 5AA cross-sectional view showing a portion of bearing cover 300A according to the first embodiment is shown. Bearing cover 300A includes a first air-insulated cavity 430A and a second air-insulated cavity 430B. The primary heat flux direction 500 is from the first surface 410 to the second surface 420 and through the first air-insulated cavity 430A. Experiments by computer simulation for one particular implementation of this first embodiment indicate that the thermal mass / cold mass ratio, which represents the quality ratio used to determine the structural integrity, is approximately 1.23. The higher the ratio, the more thermal mass and the greater the stress experienced by the cold side.

[0043] The first air-insulated cavity 430A includes a first portion 432 extending from a first end 433 to an apex 434 and a second portion 436 extending from the apex 434 to a second end 437. In a cross-sectional plane including the longitudinal axis L, the first portion 432 radially outward from the second portion 436 extends away from the longitudinal axis L and toward the side of the bearing cover 300A on which the second surface 420 lies at a first angle relative to the longitudinal axis L. In this same cross-sectional plane, the second portion 436 radially inward from the first portion 432 extends away from the longitudinal axis L and toward the side of the bearing cover 300A on which the first surface 410 lies at a second angle relative to the longitudinal axis L. The first and second angles can be different. For example, the first angle can be between 40 and 55 degrees (e.g., 45-50 degrees) and the second angle can be between 130 and 145 degrees (e.g., 135-140 degrees). More generally, one or both of the first portion 432 or the second portion 436 can extend away from the longitudinal axis L at a non-zero and / or non-perpendicular angle relative to the longitudinal axis L.

[0044] The first air-insulated cavity 430A is shaped to generally follow the contours of the first surface 410 and the second surface 420, and preferably, the contours of the oil sump 425, but uses a generally right angle at the apex 434 to facilitate the additive manufacturing process. For example, the angle between the first portion 432 and the second portion 436 can be between 40 and 55 degrees, and preferably, between about 45 and 50 degrees.

[0045] The second air-insulated cavity 430B downstream of the first air-insulated cavity 430A is substantially parallel to the longitudinal axis L and is shorter in overall length than the first air-insulated cavity 430A. Essentially, the second air-insulated cavity 430B forms a radially inner boundary along the oil sump 425 to reduce heat flux from the radially inward facing portion of the first surface 410 toward the second surface 420. In alternative embodiments, the second air-insulated cavity 430B can extend axially upstream to join the second end 437 of the first air-insulated cavity 430A, thereby forming a single continuous air-insulated cavity 430. However, this can not be practical for additive manufacturing processes. Thus, in the illustrated embodiment, the air-insulated cavity 430 is divided into the first air-insulated cavity 430A and the second air-insulated cavity 430B. More generally, the air-insulated cavity(s) 430, whether a single continuous air-insulated cavity 430 or multiple discrete air-insulated cavities 430, has a profile that matches the profile of the oil sump 425 but uses two or more linear segments.

[0046] In embodiments, one or both of the first end 433, which is the radially outermost end of the first air-insulated cavity 430A, or the second end 437, which is the radially innermost end of the first air-insulated cavity 430A, can have a teardrop shape. Similarly, the ends of the second air-insulated cavity 430B can have a teardrop shape (as shown in FIGS. 4B and 4C). Figure 6A and 6B More generally, the ends of any air-insulated cavity 430 can have a teardrop shape. This teardrop shape reduces stress at these filleted points.

[0047] Figure 5B A cross-sectional view of a portion of a bearing cover 300B according to a second embodiment is shown. As in the first embodiment of the bearing cover 300A, the bearing cover 300B includes a first air-insulated cavity 430A. However, the bearing cover 300B does not include a second air-insulated cavity 430B. Additionally, the bearing cover 300B includes a closed hybrid air cavity 440. In all other respects, the bearing cover 300B can be the same as or similar to the bearing cover 300A. Thus, it should be understood that any description of a component with respect to the bearing cover 300A that also exists in the bearing cover 300B can equally apply to that component in the bearing cover 300B. Computer simulated experiments for one particular implementation of this second embodiment indicate a thermal mass / cold mass ratio of about 1.29.

[0048] Since the mixing air cavity 440 is enclosed, the bearing cap 300B can include one or more mixing air inlets 445 in fluid communication with the mixing air cavity 440. Thus, air can flow from the radial interior environment of the bearing cap 300B into the mixing air cavity 440 through the mixing air inlet(s) 445 (e.g., in the mixing air cavity, the air can flow into the mixing air passage 450 - see Figure 4A , 4B ). In embodiments, the bearing cap 300B can include a plurality of mixing air inlets 445 that are radially oriented and positioned at equidistant intervals around the inner circumference of the bearing cap 300B, for example, between the air seal 230 and the oil seal 240. Further, additive manufacturing can be designed to have the mixing air inlets 445 serve as powder removal outlets to allow for faster powder removal.

[0049] Figure 5C A cross-sectional view of a portion of a bearing cap 300C according to a third embodiment is shown. The bearing cap 300C is similar to the bearing cap 300B in the second embodiment, but includes a smaller mixing air cavity 440 than in the bearing cap 300B. In all other respects, the bearing cap 300C can be the same or similar to the bearing cap 300B. Thus, it should be understood that any description of a component with respect to the bearing cap 300B that is also present in the bearing cap 300C can apply equally to that component in the bearing cap 300C. Computer simulated experiments for one particular implementation of this third embodiment indicate that the hot mass / cold mass ratio is approximately 2.61. Additionally, the third embodiment has a much larger hot side mass than the second embodiment.

[0050] Figure 6A The placement of the powder removal holes 600 according to the first embodiment is shown in a perspective cross-sectional view of a section of the bearing cap 300. In this first embodiment, a first powder removal hole 600X is radially oriented and positioned at a first end 433 of the first air insulation cavity 430A, a second powder removal hole 600Y is axially oriented and positioned at an apex 434 of the first air insulation cavity 430A, and a third powder removal hole 600Z is axially oriented and positioned at a downstream end of the second air insulation cavity 430B.

[0051] Figure 6B The placement of the powder removal holes 600 according to the second embodiment is shown in a perspective cross-sectional view of a section of the bearing cap 300. In this second embodiment, the first powder removal hole 600X and the third powder removal hole 600Z are the same as in the first embodiment. However, in the second embodiment, the second powder removal hole 600Y is positioned at a second end 437 of the first air insulation cavity 430A. Additionally, the second powder removal hole 600Y is oriented perpendicular to the portion of the second surface 420 proximate the second end 437.

[0052] Each powder removal hole 600 includes a passageway from the air-insulated cavity 430 to an external environment of the bearing cover 300. The powder removal holes 600 enable powder produced during the additive manufacturing process to be flushed out of the air-insulated cavity(s) 430 using, for example, a fluid (e.g., air, liquid, etc.) and / or gravity. It should be appreciated that each powder removal hole 600 can be printed during the additive manufacturing process.

[0053] Figure 7 An air-insulated cavity 430 within a bearing cover 300 is shown as viewed downwardly along the longitudinal axis L in accordance with an embodiment. The air-insulated cavity 430A is shown in both a transparent view (top) as well as a solid view (bottom). The bearing cover 300 can be printed with a plurality of powder removal holes 600 during the additive manufacturing process. For illustrative purposes, four strategically placed powder removal holes 600A, 600B, 600C, and 600D are labeled. The strategic placement of these powder removal holes 600A-600D is targeted to minimize the number of powder removal holes 600 required for powder removal in order to minimize stress concentration locations and reduce post-manufacturing handling. Although a certain number of powder removal holes 600 are shown, it should be appreciated that embodiments can include fewer or more powder removal holes 600 than shown.

[0054] As a first example, the bearing cover 300 can be rotated 90 degrees from the orientation shown such that powder removal holes 600A and 600B are at the top and powder removal holes 600C and 600D are at the bottom, and then air or other fluid can be supplied through powder removal holes 600A and 600B as inlets to flush out powder through powder removal holes 600C and 600D as outlets. As a second example, the bearing cover 300 can be rotated 67.5 degrees such that powder removal holes 600A and 600C are straight in the vertical, and then air or other fluid can be supplied through powder removal hole 600A as an inlet to flush out powder through powder removal hole 600C as an outlet. Similarly, as a third example, the bearing cover 300 can be rotated 112.5 degrees such that powder removal holes 600B and 600D are straight in the vertical, and then air or other fluid can be supplied through powder removal hole 600B as an inlet to flush out powder through powder removal hole 600D as an outlet. It should be appreciated that the bearing cover 300 can be rotated to various other orientations that use at least one powder removal hole 600 as an inlet and at least one powder removal hole 600 as an outlet that enable gravity to assist with powder removal.

[0055] Figure 8An additive manufacturing process 800 for manufacturing a bearing cover 300 according to an embodiment is shown. Initially, in sub-process 810, the bearing cover 300 can be printed layer-by-layer using additive manufacturing and a suitable material (e.g., a nickel alloy such as IN718). The bearing cover 300 can be printed to include: a first surface 410 on a first side, where the first surface 410 is annular about the longitudinal axis L; a second surface 420 on a second side opposite and downstream from the first side (“opposite and downstream from” means that, with respect to an area on the first surface 420, there is a corresponding area on the second surface 420 that is separated from the area on the first surface 410 in a direction parallel to the longitudinal axis L and further away from the compressor 120), where the second surface 420 is annular about the longitudinal axis L; at least one air-insulated cavity 430 (e.g., 430A) between the first surface 410 and the second surface 420, where the at least one air-insulated cavity 430 is annular about the longitudinal axis L; and one or more powder removal holes 600 extending from one or both of a radially innermost end (e.g., 437) of the at least one air-insulated cavity 430 or a radially outermost end (e.g., 433) of the at least one air-insulated cavity 430 to an external environment of the bearing cover 300. In a cross-sectional plane including the longitudinal axis L, a radially outer first portion 432 of the at least one air-insulated cavity 430 can extend away from the longitudinal axis L and toward the second side at a first angle relative to the longitudinal axis L, a radially inner second portion 436 of the at least one air-insulated cavity 430 can extend away from the longitudinal axis L and toward the first side at a second angle relative to the longitudinal axis L, and / or the radially innermost end (e.g., 437) of the at least one air-insulated cavity 430 or the radially outermost end (e.g., 433) of the at least one air-insulated cavity 430 can have a teardrop shape.

[0056] In sub-process 820, powder can be flushed from the at least one air-insulated cavity 430 via the one or more powder removal holes 600. For example, as described above, the printed bearing cover 300 can be rotated to provide at least one powder removal hole 600 at a top to serve as an inlet and at least one powder removal hole 600 at a bottom to serve as an outlet. The bearing cover 300 can then be mounted on a fixture to use gravity and vibration to remove powder to allow the powder to be drained. Additionally, a fluid such as air or liquid can be pumped through the inlet to flush the powder out of the at least one air-insulated cavity 430 through the outlet. This flushing can be performed in multiple steps. For example, a first flushing can be performed while the bearing cover 300 is still fixed to a build plate on which the bearing cover 300 was printed, and a second flushing can be performed after the bearing cover 300 has been removed from the build plate (e.g., by an electrical discharge machining (EDM) wire cut).

[0057] Alternatively, the printed bearing cap 300 can undergo heat treatment to relieve residual stresses in the printed bearing cap 300. Heat treatment can relieve stresses by subjecting the printed bearing cap 300 to high temperatures and then controlled cooling. This reduces the risk of distortion, warping, or cracking and improves dimensional stability.

[0058] In sub-process 830, after flushing powder from the at least one air-insulated cavity 430, one or more powder removal holes 600 can be plugged. For example, a pin can be welded or otherwise secured into each powder removal hole 600, thereby sealing the at least one air-insulated cavity 430.

[0059] Industrial applicability

[0060] Bearing caps protect bearings in a gas turbine engine 100 and generally include an oil sump that provides lubricating oil to the bearings. However, in conventional bearing caps, the oil-wetted surfaces that define the oil sump can be subjected to temperatures in excess of 400 degrees Fahrenheit. Such high temperatures can cause oil degradation, oil paint film, and coking, which can cause oil drain blockage and, in extreme cases, can cause a fire.

[0061] Accordingly, a bearing cap 300 is disclosed that reduces the temperature to which the oil-wetted second surface 420 is subjected. In particular, the bearing cap 300 can include one or more air-insulated cavities 430 that provide a thermal barrier to the heat flux 500 through the bearing cap 300. The air-insulated cavity(s) 430 can collectively form a profile that matches the profile of the oil sump 425 to provide a thermal barrier around a majority or all of the oil sump 425. As a result, the thermal mass / cold mass ratio between the first surface 410 and the second surface 420 can be significantly reduced.

[0062] It will be understood that the benefits and advantages described above can relate to one embodiment or can relate to several embodiments. Aspects described in connection with one embodiment can be applicable to other embodiments. Any

[0063] As used herein, the term "annular" encompasses objects shaped to completely surround an axis of rotation (e.g., the object is disposed 360 degrees around the axis of rotation), as well as objects shaped to only partially surround an axis of rotation (e.g., the object is disposed 180 degrees around the axis of rotation).

[0064] The foregoing detailed description has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise form disclosed. The described embodiments were described with an industrial context in mind but are not intended to be limited to use in conjunction with a particular type of industrial background or a particular type of machine. Thus, although the embodiments have been depicted and described as being implemented with a gas turbine engine for ease of explanation, it will be appreciated that it can be implemented in connection with various other types of machines having bearing covers and in various other environments. Moreover, it is not intended to be bound by any theory presented in any preceding section. It is also to be understood that the illustrations can include exaggerated dimensions and graphic representations to better illustrate the referenced items shown and are not to be considered limiting unless specifically stated.

Claims

1. A bearing cap (300) for a gas turbine engine (100), the bearing cap (300) comprising: A first surface (410) on a first side, wherein the first surface (410) is annular about a longitudinal axis (L); A second surface (420) on a second side opposite to and downstream of the first side, wherein the second surface (420) is annular about the longitudinal axis (L); and One or more air-insulating cavities (430) between the first surface (410) and the second surface (420), wherein each of the one or more air-insulating cavities (430) is annular about the longitudinal axis (L).

2. The bearing cap (300) according to claim 1, wherein, In a cross-sectional plane including the longitudinal axis (L), at least a portion of at least one of the one or more air-insulating cavities (430) extends away from the longitudinal axis (L) at a non-zero angle relative to the longitudinal axis (L).

3. The bearing cap (300) according to claim 1, wherein, In a cross-sectional plane including the longitudinal axis (L), at least a portion of at least one of the air-insulating cavities (430) extends away from the longitudinal axis (L) at a non-zero, non-perpendicular angle relative to the longitudinal axis (L).

4. The bearing cap (300) according to claim 1, wherein, In a cross-sectional plane including the longitudinal axis (L), a first portion (432) of at least one of the air-insulating cavities (430) extends away from the longitudinal axis (L) at a non-zero first angle, and a second portion (436) of at least one air-insulating cavity (430) extends away from the longitudinal axis (L) at a second angle, wherein the second angle is different from the first angle.

5. The bearing cap (300) according to claim 1, wherein, In a cross-sectional plane including the longitudinal axis (L), at least a radially outer first portion (432) of the first air insulating cavity (430) of the one or more air insulating cavities (430) extends away from the longitudinal axis (L) and toward the second side at a first angle relative to the longitudinal axis (L), and a radially inner second portion (436) of the first air insulating cavity (430A) extends away from the longitudinal axis (L) and toward the first side at a second angle relative to the longitudinal axis (L).

6. The bearing cap (300) according to claim 5, wherein, In the cross-sectional plane, one or both of the innermost radial end (437) or the outermost radial end (433) of the first air insulation cavity (430A) have a teardrop shape.

7. The bearing cap (300) according to claim 5, further comprising one or more powder removal holes (600) extending from one or both of the radial innermost end (437) or the radial outermost end (433) of the first air insulation cavity (430A) to the external environment of the bearing cap (300).

8. The bearing cap (300) according to claim 5, further comprising one or more powder removal holes (600) extending from a vertex (434), the vertex being formed at the point where the first portion (432) and the second portion (436) of the first air insulation cavity (430A) meet.

9. The bearing cover (300) according to claim 5, wherein the one or more air insulation cavities (430) are a plurality of air insulation cavities (430A, 430B), and wherein, In the cross-sectional plane, the second air insulation cavity (430B) of the plurality of air insulation cavities is shorter in total length than the first air insulation cavity (430A).

10. The bearing cap (300) according to claim 9, wherein, In the cross-sectional plane, the second air-insulating cavity (430B) is parallel to the longitudinal axis (L).

11. The bearing cap (300) according to claim 10, wherein the second air insulation cavity (430B) is downstream of the radially innermost end of the first air insulation cavity (430A).

12. The bearing cap (300) according to claim 9, further comprising one or more powder removal holes (600) extending from at least one end of the second air insulation cavity (430B) to the external environment of the bearing cap (300).

13. The bearing cap (300) according to claim 1, wherein the second surface (420) defines an oil reservoir (425) on the second side; and in, In the cross-sectional plane, the contours of the one or more air-insulating cavities (430) match the contours of the oil sump (425).

14. The bearing cap (300) according to claim 1, further comprising an annular mixing air cavity (440) upstream of the one or more air insulating cavities (430).

15. The bearing cap (300) according to claim 1, further comprising one or more sealing rings (230, 240) on a radially inwardly facing surface of the bearing cap (300), the one or more sealing rings surrounding a central channel through the bearing cap (300).

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