A gas foil thrust bearing

Abstract

The application discloses a gas foil thrust bearing, which comprises a bearing seat and a gas foil thrust bearing assembly arranged on the bearing seat; the gas foil thrust bearing assembly comprises a top foil, a middle foil and a bottom foil; the middle foil and the bottom foil are in surface contact; the bottom foil is arranged on the bearing seat, and the initial contact state of the bottom foil and the bearing seat is linear contact, and the loading state is surface contact; the top foil comprises wedge-shaped foil elements and a starting end welding position hole and a terminal which are separately arranged on both sides of the wedge-shaped foil elements; the starting end welding position hole is fixed on a middle foil upper surface, and the terminal is suspended relative to the middle foil upper surface; a plurality of wedge-shaped foil elements are uniformly distributed in a ring shape on the middle foil upper surface; the bottom foil comprises a bottom foil matching ring and elastic elements arranged on a bottom foil matching ring lower surface and having a certain inclination angle with the bottom foil matching ring. In the application, the middle foil and the bottom foil are in complete surface contact, which is beneficial to the uniform distribution of the foil structure temperature field when the aerodynamic heat is transmitted, and prevents the foil from being subjected to uneven thermal deformation.

Description

Technical Field

[0001] This invention relates to the field of rotating machinery, and more particularly to a gas foil thrust bearing. Background Technology

[0002] Currently, due to the excellent characteristics of hydrodynamic gas foil bearings, such as high operating speed, high temperature, low frictional resistance, low operating cost and small mass, after years of development and iteration, they have been widely used in high-speed rotating machinery such as aerospace, high-speed motors, turbine compressors, turbopumps, gas turbines and turbine generators.

[0003] Existing gas foil thrust bearing designs typically employ a series of separate plates, sometimes using a non-planar construction to provide a resilient effect.

[0004] Such existing designs not only make manufacturing overly complex, but also result in poor performance due to excessive friction, especially at low speeds per minute.

[0005] Specifically, hydrodynamic gas foil thrust bearings typically employ an elastic bottom foil axially supported by a bearing housing, a top foil, and a force-transmitting middle foil. After the rotating thrust disk begins to rotate, a thin layer of fluid is formed between the top foil and the rotating thrust disk. This fluid provides axial support to the thrust disk, thereby forming a low-friction hydrodynamic air bearing; furthermore, the fluid transfer facilitates heat transfer.

[0006] The thrust disk is usually flat, while the foil elements are usually wedge-shaped and convergent along the circumference. This circumferential surface inclination leads to the formation of a fluid film and gives the thrust disk an axial lifting effect.

[0007] In this way, the axial load applied by the rotating thrust disk can be transmitted to the bearing housing through the fluid film, top foil, middle foil and bottom foil. The bearing housing provides an axial reaction force of equal magnitude and opposite direction to match the axial load applied to the bearing.

[0008] The presence of a fluid film in this force transmission chain makes it possible to significantly reduce frictional losses that may occur due to relative rotation between surfaces.

[0009] Therefore, hydrodynamic gas foil thrust bearings can be used in micro gas turbines to overcome the impracticality of other traditional types of bearings under high speed and high operating temperature conditions.

[0010] However, the top foil, middle foil and bottom foil are usually in line contact or partial surface contact, which can easily lead to uneven temperature distribution of the foil, causing uneven thermal deformation of the top foil and damage to the lubricating gas film. In addition, this traditional contact method is prone to stress concentration after the gas film pressure is generated, which can also cause uneven deformation of the foil, causing the top foil to come into contact with the rotor and wear. Summary of the Invention

[0011] The purpose of this invention is to overcome the shortcomings of the prior art and provide a gas foil thrust bearing that can solve the above-mentioned problems.

[0012] To solve the above-mentioned technical problems, the technical method adopted by the present invention is as follows: The present invention discloses a gas foil thrust bearing, including a bearing housing and a gas foil thrust bearing assembly disposed on the bearing housing; characterized in that: the gas foil thrust bearing assembly includes a top foil, a middle foil and a bottom foil; the middle foil and the bottom foil are in surface contact; the bottom foil is disposed on the bearing housing, and the initial contact state between the bottom foil and the bearing housing is line contact, and the loading state is surface contact; The top foil includes a wedge-shaped foil element and starting end solder holes and an end point respectively disposed on both sides of the wedge-shaped foil element; The starting end welding hole is fixed on the upper plane of the middle foil, and the terminal is suspended relative to the upper plane of the middle foil; a plurality of the wedge-shaped foil elements are evenly distributed in a ring on the upper plane of the middle foil; The bottom foil includes a bottom foil mating ring and an elastic element disposed on the lower plane of the bottom foil mating ring at a certain angle to the bottom foil mating ring.

[0013] Furthermore, the bottom foil mating ring is provided with a matrix of several circumferentially equidistant through holes; the elastic element is provided on one side of the through holes; the elastic element is arranged along the circumferential direction of the bottom foil mating ring in the length direction.

[0014] Furthermore, the through-hole matrix includes through-holes radially distributed along the bottom foil mating ring and through-holes circumferentially distributed along the bottom foil mating ring.

[0015] Furthermore, along the circumferential direction of the bottom foil mating ring, two adjacent elastic elements are arranged symmetrically.

[0016] Furthermore, along the radial direction of the bottom foil mating ring, two adjacent elastic elements are arranged symmetrically at the center.

[0017] Furthermore, the annular mating surface of the bearing housing is flat but rough.

[0018] Furthermore, the middle foil, the bottom foil, and the bearing seat are sequentially provided with coaxial positioning through holes for the middle foil, positioning through holes for the bottom foil, and positioning through holes for the bearing seat, all having the same diameter. Beneficial effects

[0019] 1. Compared with the prior art, in this invention, the middle foil and the bottom foil are in complete surface contact, which is beneficial to the uniform distribution of the temperature field of the foil structure when transferring aerodynamic heat and prevents uneven thermal deformation of the foil; the elastic elements of the bottom foil are evenly distributed, which can solve the problem of uneven deformation of the foil caused by air film pressure.

[0020] 2. The angle between the elastic element and the bottom foil mating ring in this invention enables the foil assembly to have a large deformation capacity, reducing bearing wear caused by insufficient foil deformation capacity during operation. Simultaneously, pre-tightening assembly during rotor assembly allows the elastic element to undergo a certain pre-deformation, improving bearing stiffness and thus increasing bearing load-bearing capacity. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the gas foil thrust bearing in this invention; Figure 2 This is a schematic diagram of the explosion of the gas foil thrust bearing in this invention; Figure 3 This is a schematic diagram of the specific structure of the top foil in this invention; Figure 4 This is a schematic diagram of the specific structure of the foil in this invention; Figure 5 A schematic diagram of the specific structure of the bottom foil in this invention; Figure 6 A schematic diagram of the upper surface of the bottom foil in this invention; Figure 7 A schematic diagram of the lower surface of the bottom foil in this invention; Figure 8 A schematic diagram of the specific structure of the bearing housing in this invention. Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0023] Figure 1-7 The specific structure of the gas foil thrust bearing is described. The gas foil thrust bearing includes a gas foil thrust bearing assembly 100 and a bearing housing 200. The gas foil thrust bearing assembly 100 includes a top foil 110, a middle foil 120, and a bottom foil 130.

[0024] like Figure 1As shown, the wedge-shaped foil element 114, the middle foil annular mating ring 122, the bottom foil annular mating ring 132, and the bearing housing annular mating surface 242 are stacked sequentially. Before the bearing operates, the load is transferred from the wedge-shaped foil element 114 to the bottom foil annular mating ring 132 via the middle foil mating ring 122. The bottom foil mating ring then transfers the load to the elastic element 134. After the elastic element is subjected to force, the angle between it and the bottom foil annular mating ring 132 decreases.

[0025] The middle foil 120 has a flat surface, and the bottom foil 130 has a flat bottom foil mating ring 132. The top foil 110 has a non-planar structure, while the middle foil 120 and the bottom foil 130 are planar.

[0026] The top foil 110, middle foil 120, bottom foil 130, and bearing seat 200 are provided with the same through hole at their center positions.

[0027] The wedge-shaped foil elements 114 can be evenly distributed on the circumference of the annular mating ring 122 of the middle foil. The wedge-shaped foil elements 114 are arranged circumferentially along the circumferential direction of the annular mating ring 122 of the middle foil, such as... Figure 3 As shown. This periodic distribution, especially when combined with the correspondingly distributed force transmission elements, foil mating ring 122 and bottom foil mating ring 132, is conducive to forming a uniform circumferential load distribution and helps to prevent any local stress concentration that may increase losses and wear.

[0028] like Figure 3 As shown, the top foil 110 suitable for receiving a rotating thrust disk includes a wedge-shaped foil element 114 and starting end welding holes 113 and an end 115 respectively disposed on both sides of the wedge-shaped foil element 114.

[0029] The starting end welding hole 113 is fixed to the annular mating ring 122 of the middle foil, but the end 115 needs to remain free to release the deformation caused by gas film pressure or thermal stress.

[0030] The top foil 110 includes a plurality of radially inwardly arranged wedge-shaped foil elements 114. The wedge-shaped foil elements 114 are configured to provide an axially converging wedge in the circumferential direction. This circumferential undulation generates a fluid film as the adjacent thrust disk rotates, which serves to provide axial support to the rotating thrust disk.

[0031] During startup and normal operation, the axial force exerted by the rotating thrust disk on the top of the top foil 110 is not constant. This load variation is accommodated in the thrust bearing by providing compliance (i.e., elasticity) in the form of a lower spring mechanism consisting of elastic elements 134 coupled to the lower bottom foil 130 of the top foil.

[0032] like Figure 4 The shown foil 120 includes a foil annular mating ring 122 and four positioning holes 126.

[0033] The annular mating ring 122 of the middle foil can be planar and contact the bottom of the top foil 114. As shown in the figure, the middle foil 120 may include a through hole 126 for positioning the middle foil disposed on its radial outer edge.

[0034] like Figure 5-7 The bottom foil 130 shown includes a bottom foil annular mating ring 132 and elastic elements 134 arranged clockwise and counterclockwise along the circumference of the bottom foil annular mating ring 132. The elastic elements 134 can extend circumferentially from the bottom foil annular mating ring 132.

[0035] The middle foil 120 and bottom foil 130 of the thrust bearing assembly 100 facilitate the axial transfer of the axial load generated by the wedge-shaped foil elements 114 of the top foil 110. In particular, each circumferentially spaced wedge-shaped foil element 114 can be supported by a corresponding pair of axially overlapping annular mating rings 122 of the middle foil and annular mating rings 132 of the bottom foil.

[0036] The overlapping pairs of force transmission elements and elastic elements may include circumferential and / or radial offset portions, that is, the circumferential and / or radial offset portions of the force transmission elements are offset from or do not overlap with the circumferential and / or radial offset portions of the elastic elements.

[0037] like Figure 6-7 As shown, the bottom foil 130 has an annular mating ring 132 and an elastic element 134. The elastic element 134 is inclined to the bottom foil annular mating ring 132, forming a certain angle. This angle can be controlled to form a fixed angle during processing.

[0038] Each elastic element 134 may include a circumferentially extending support in clockwise and counterclockwise directions, and the elastic element 134 has a certain included angle with the bottom foil annular mating ring 132. θ In order to fully utilize the elastic properties of elastic elements.

[0039] The bottom foil 130 includes a bottom foil positioning through hole 246 disposed on its radial outer edge for receiving an upper or lower plate.

[0040] The bottom foil positioning through hole 246 corresponds to the positioning holes of the upper middle foil 120 and the top foil 110, securely fixing the plates of the thrust bearing assembly 100 together.

[0041] like Figure 8 The bearing housing 200 shown includes a bearing housing annular mating surface 242 and a bearing housing positioning through hole 246. The bearing housing annular mating surface 242 is a flat plane, but the surface needs to be roughened. When the mating elastic element 134 deforms, it slides on the surface of the bearing housing annular mating surface 242. The roughness is expressed as the coefficient of friction to control the degree of slippage of the elastic element 134.

[0042] The axial elasticity of the elastic element 134 promotes the conformability of the bottom foil. Thus, the elastic element 134 can be regarded as a cantilever extending circumferentially.

[0043] Each wedge-shaped foil element 114 can be supported by a lower force-transmitting element. The force-transmitting element includes the wedge-shaped foil element 114, the middle foil annular fitting ring 122, the bottom foil annular fitting ring 132, and the elastic element 134.

[0044] Therefore, the load applied by the rotating thrust disk through the fluid film can be transmitted through the wedge foil element 114, through the corresponding force transmission element, to the corresponding elastic element 134; this can cause the elastic element 134 to slide radially on the surface of the bearing housing annular mating surface 242 and generate axial deformation to adapt to the gas film pressure.

[0045] The bearing housing annular mating surface 242 can be used to limit the elasticity of the elastic element 134 by contacting the elastic element 134 after the elastic element 134 has developed sufficient elasticity.

[0046] The downward axial load on the force transmission element can be transmitted to the elastic element 134 through the mating ring 122. The elastic element 134 is in line contact with the annular mating surface 242 of the bearing housing, and the line contact is converted to the surface contact when preload and load are applied to increase the friction.

[0047] The layers of foil in the gas foil thrust bearing assembly 100 can be stacked so that each wedge foil element 114 is axially supported by a pair of corresponding, axially overlapping force transmission elements and elastic elements 134.

[0048] like Figure 1 As shown, the top foil 110 covers the middle foil 120, and the middle foil 120 covers the bottom foil 130. If the assembly 100 and the bearing housing 200 are combined, the bottom foil 130 covers the bearing housing 200.

[0049] The specific stacking order is as follows: the bottom foil 130 is positioned on the bearing seat 200, the middle foil 120 is positioned on the bottom foil 130, and finally the top foil 110 is positioned on the middle foil 120.

[0050] During or after stacking, the plates can be oriented so that the wedge foil elements 114 are axially supported by corresponding pairs of overlapping force-transmitting elements and elastic elements 134.

[0051] Each foil is oriented such that each wedge-shaped foil unit 114 covers the corresponding force-transmitting element, and the force-transmitting element covers the corresponding elastic element 134. Thus, the force transmitted from each wedge-shaped foil element 114 can be transmitted to the corresponding elastic element 134 through the corresponding force-transmitting element. The force applied to the elastic element 134 can cause the elastic element 134 to undergo axial displacement relative to the bottom foil mating ring 132. The direction of displacement is axially away from the top foil 110.

[0052] The presence of the included angle between the elastic element 134 and the bottom foil mating ring 132 enables the foil assembly 100 to have a large deformation capability, allowing for pre-tight assembly during rotor assembly. This allows the elastic element 134 to undergo a certain degree of pre-deformation, improving bearing stiffness and thus enhancing bearing load capacity.

[0053] In some existing technologies, corrugated foils are provided to facilitate compliance, which tends to cause plastic deformation during use; according to an example of the present invention, the body foil thrust bearing assembly 100 disclosed in the present invention improves the possibility of preventing such plastic deformation.

[0054] In the example disclosed in this invention, a gas foil thrust bearing assembly 100 for direct positioning on the bearing housing 200 is provided, which has a minimum number of plates, thus reducing manufacturing complexity and performance variation compared to using a larger number of plates.

[0055] Compared to existing technologies, in this application, the middle foil 120 and the bottom foil 130 are in complete surface contact. This facilitates a uniform temperature field distribution within the foil structure during aerodynamic heat transfer, preventing uneven thermal deformation of the foil. The uniform distribution of the elastic elements 134 on the bottom foil 130 effectively addresses the problem of uneven foil deformation caused by film pressure. The angle between the elastic elements 134 and the mating ring 132 of the bottom foil allows the foil assembly 100 to exhibit large deformation capabilities, reducing bearing wear caused by insufficient foil deformation during operation. Furthermore, pre-tightening during rotor assembly allows for a certain degree of pre-deformation of the elastic elements 134, improving bearing stiffness and ultimately enhancing bearing load capacity.

[0056] Although the embodiments provided by the present invention give specific geometric structures of force transmission elements and elastic elements 134, the general principles of the present invention are applicable to a wide variety of geometric structures.

[0057] The thickness of the middle foil 120 can be greater than that of the bottom foil 130, or it can be greater than that of the top foil 110. For example, providing a middle foil that is thicker than the bottom foil prevents performance degradation associated with middle foil deformation. The increased thickness of the middle foil helps to distribute the force to be transmitted evenly over a larger working area of ​​the top foil.

[0058] The thickness of the top foil 110 can be between 0.075 and 0.175 mm.

[0059] The thickness of the medium foil 120 can be between 0.1 and 0.2 mm or between 0.15 and 0.25 mm.

[0060] The thickness of the base foil 130 can be between 0.075 and 0.15 mm.

[0061] Each example disclosed in this invention can be incorporated into high-speed rotating machinery including a gas foil thrust bearing according to any example. The use of such a gas foil thrust bearing in high-speed rotating machinery improves the performance characteristics of the machinery due to improved management of frictional losses and heat, and simplifies manufacturing. It should be understood that the examples disclosed in this invention are not limiting and numerous modifications and substitutions are possible.

Claims

1. A gas foil thrust bearing comprising a bearing housing (200) and a gas foil thrust bearing assembly (100) disposed on the bearing housing (200); characterized by: The gas foil thrust bearing assembly (100) includes a top foil (110), a middle foil (120), and a bottom foil (130); the middle foil (120) and the bottom foil (130) are in surface contact; the bottom foil (130) is disposed on the bearing seat (200), and the bottom foil (130) and the bearing seat (200) are initially in line contact and in surface contact under load. The top foil (110) includes a wedge-shaped foil element (114) and starting end solder holes (113) and an end (115) respectively disposed on both sides of the wedge-shaped foil element (114). The starting end welding hole (113) is fixed on the upper plane of the middle foil (120), and the terminal (115) is suspended relative to the upper plane of the middle foil (120); a plurality of the wedge-shaped foil elements (114) are evenly distributed in a ring on the upper plane of the middle foil (120); The bottom foil (130) includes a bottom foil mating ring (132) and an elastic element (134) disposed on the lower plane of the bottom foil mating ring (132) and at a certain angle to the bottom foil mating ring (132). The bottom foil mating ring (132) is provided with a matrix of through holes distributed equidistantly around the circumference; the elastic element (134) is provided on one side of the through holes; the elastic element (134) is arranged along the circumference of the bottom foil mating ring (132) in the length direction; The through-hole matrix includes through holes radially distributed along the bottom foil mating ring (132) and through holes circumferentially distributed along the bottom foil mating ring (132); Along the circumferential direction of the bottom foil mating ring (132), two adjacent elastic elements (134) are arranged symmetrically. Along the radial direction of the bottom foil mating ring (132), two adjacent elastic elements (134) are arranged symmetrically at the center.

2. The gas foil thrust bearing of claim 1, wherein: The bearing housing (200) has a flat but rough annular mating surface (242).

3. The gas foil thrust bearing according to claim 1, characterized in that: The middle foil (120), bottom foil (130), and bearing seat (200) are sequentially provided with coaxial and identical positioning through holes (126), positioning through holes (136), and positioning through holes (246) for the middle foil, bottom foil, and bearing seat.

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