A dual wave foil nested gas gas foil bearing with textured top foil

Abstract

The application discloses a double-wave-foil nested radial gas wave foil bearing with a textured top foil, which comprises a bearing sleeve, a top foil, and an outer wave foil and an inner wave foil arranged in a nest, wherein the inner surface of the top foil is provided with circular micro-pits and axially communicating grooves which are uniformly distributed in the circumferential direction; the two layers of wave foils are one-to-one corresponding and coaxial; the top circular arc surface of the outer wave foil is in contact with the surface of the bearing sleeve; and the bottom pointed arch of the outer wave foil supports the inner wave foil. The bottom circular arc surface of the inner wave foil is in contact with the surface of the top foil; and the top pointed arch of the inner wave foil reversely supports the outer wave foil, so as to form a bidirectional limiting and supporting structure. The application disperses stress by surface contact, reduces abrasion, realizes graded rigidity by means of the height difference of the wave foils, strengthens the gas film dynamic pressure effect by the micro-texture of the top foil, improves the carrying capacity, and restrains the rotor vibration. The structure is simple in processing and assembly, stable in operation, long in service life, and suitable for various complex working conditions.

Description

Technical Field

[0001] This invention relates to the field of gas dynamic bearing technology, and in particular to an improved double-wave foil nested gas wave foil bearing support structure with a pit-groove composite microtexture. Background Technology

[0002] Gas foil bearings use gas as a lubricant and have advantages such as high speed, low friction and wear, oil-free lubrication, and simple structure. They have broad application prospects in high-speed rotating machinery such as aero engines, micro gas turbines, and high-speed centrifugal compressors.

[0003] A typical gas foil bearing consists of a bearing sleeve, a top foil, and corrugated foils. The corrugated foils, acting as elastic support elements, directly determine the bearing's stiffness, damping characteristics, load-bearing capacity, and stability. Currently, traditional corrugated foil bearings mostly have a single-layer corrugated foil structure, with the corrugation arches typically being a single wavy protrusion. In practical applications, the contact between the corrugated foil and the bearing sleeve / top foil is often line or point contact, leading to excessively high local contact stress. This can easily cause plastic deformation, wear, or even fatigue fracture in the contact area between the corrugated foil and the bearing sleeve, significantly reducing the bearing's service life. Furthermore, the frictional damping of a single-layer corrugated foil only comes from the contact friction between the corrugation arches and the bearing sleeve / top foil, resulting in a low damping value. Under high-speed conditions, this makes it difficult to effectively suppress vibration transmission in the rotor system.

[0004] Meanwhile, the top foil of existing gas wave foil bearings generally adopts a smooth inner surface structure. When running at high speed, the smooth surface makes it difficult to actively control the airflow distribution, resulting in poor uniformity of gas film pressure and insufficient gas film damping, which can easily induce gas film vortex and further affect the bearing's operational stability.

[0005] While there are some improved solutions for double-layer corrugated foil structures in the existing technology, most of them are simple overlapping of corrugated arches, without optimization in terms of contact form and support force transmission path, and still do not solve the problems of contact stress concentration and weak stiffness adjustment capability.

[0006] Currently, there are few modified designs for the top foil surface in the industry, which cannot simultaneously meet the comprehensive needs of gas storage and buffering, airflow guidance and pressure equalization and vibration reduction, resulting in limited application effects.

[0007] Therefore, optimizing the corrugated foil support structure and the surface morphology of the top foil simultaneously, and developing a gas corrugated foil bearing with excellent comprehensive performance, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0008] To address the aforementioned problems, the present invention aims to provide a double-wave foil nested support structure and a textured top foil structure for a radial gas foil bearing. Through the synergistic effect of the nested double-wave foils, it achieves optimized contact form, dispersed contact stress, graded adjustable stiffness characteristics, and improved damping characteristics. Simultaneously, the addition of a composite microtexture on the inner surface of the top foil further improves the gas film lubrication effect, enhances the gas film vibration reduction capability, improves the anti-instability capability of the wave foil, extends bearing service life, and enhances the stability of the high-speed rotor system.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A radial gas foil bearing with a double-wave foil nested support structure includes a bearing sleeve, a top foil, an outer wave foil, and an inner wave foil; the outer wave foil and the inner wave foil are both corrugated elastic metal sheets, which are arranged in a nested manner along the radial direction of the bearing, and the wave arches of the two correspond one-to-one along the circumference of the bearing.

[0011] The top of the outer corrugated foil is a circular arc surface contact section, which is in complete contact with the inner circumferential surface of the bearing sleeve to form a surface contact support; the top of the inner corrugated foil is a pointed arch support section, the apex of which abuts against the bottom of the inner circular arc surface of the outer corrugated foil, providing radial support for the circular arc surface contact section of the outer corrugated foil.

[0012] The bottom of the inner corrugated foil is a circular arc contact section, which is in complete contact with the outer circumferential surface of the top foil to form a surface contact support; the bottom of the outer corrugated foil is a pointed arch support section, the apex of which abuts against the top of the inner corrugated foil's inner circular arc surface, providing radial support for the inner corrugated foil's circular arc contact section.

[0013] The outer and inner wave foils maintain the same wave arch period, wave number, and wave amplitude, and their wave arch central axes coincide, forming a one-to-one nested support relationship. The radius of curvature of the arc-shaped contact section of the outer wave foil is the same as the radius of curvature of the inner circumference of the bearing sleeve, and the radius of curvature of the arc-shaped contact section of the inner wave foil is the same as the radius of curvature of the outer circumference of the top foil.

[0014] Furthermore, both the outer and inner wave foils are made of elastic alloy sheets with a thickness of 0.08 mm to 0.2 mm and an elastic modulus of 120 GPa to 220 GPa; the arc length of the arc-shaped contact section is 1 / 3 to 1 / 2 of the circumferential length of the wave arch, and the apex angle of the pointed arch support section is 90° to 150°.

[0015] Furthermore, the crown height of the outer corrugated foil is greater than that of the inner corrugated foil, and the difference in crown height between the two is 0.02mm~0.1mm, so as to achieve graded adjustment of the support stiffness.

[0016] Furthermore, the circumferential ends of the outer and inner wave foils are fixed to the inner circumferential surface of the bearing sleeve by spot welding or riveting to prevent the wave foils from slipping circumferentially.

[0017] Furthermore, the inner surface of the top foil is provided with a pit-groove composite microtexture. The composite microtexture includes multiple rows of circular micro-pits evenly distributed along the circumferential direction. The circular micro-pits in the same axial row are interconnected by axial micro-grooves. The aperture and depth of the circular micro-pits and the width and depth of the axial micro-grooves can be adaptively set according to the bearing specifications, speed, load and lubrication requirements. The arrangement spacing of the micro-pits and micro-grooves can also be flexibly arranged according to the actual working conditions.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] In this invention, the inner and outer corrugated foils achieve surface contact through arc-shaped contact sections, increasing the contact area compared to traditional line contact, effectively reducing contact stress, and significantly decreasing contact wear between the corrugated foil and the bearing sleeve and top foil, thus extending bearing service life. The nested double corrugated foil structure enables graded adjustment of stiffness; low stiffness and high damping during low-load start-up and shutdown effectively prevent rubbing damage, while stiffness rapidly increases during high-load and high-speed stages, significantly enhancing load-bearing capacity and stability. The nested corrugated arch structure provides mutual limiting support between the corrugated arches, preventing slippage and torsion under load, ensuring uniform bearing support stiffness distribution, and improving rotor rotation accuracy. The triple frictional damping interfaces between the inner and top foils, between the inner and outer corrugated foils, and between the outer corrugated foil and the bearing sleeve significantly improve bearing damping, effectively suppressing vibration transmission and eddy instability in the rotor system, and enhancing the stability of the high-speed rotor system.

[0020] In this invention, the pit-groove composite microtexture on the inner surface of the top foil can store gas to form a buffer cushion, which significantly reduces the direct friction and wear between the journal and the top foil during the high-speed operation of the bearing. The microgrooves can guide the airflow to flow evenly, optimize the circumferential air film pressure distribution, enhance the air film dynamic pressure effect and air film damping, further suppress air film eddy, and the increased heat dissipation area and axial cooling airflow can reduce the local temperature rise of the top foil, reduce the thermal deformation difference, and avoid air film instability caused by sudden gap changes, thereby significantly improving the reliability and overall performance of the bearing under complex operating conditions. Attached Figure Description

[0021] Figure 1 This is an exploded view of the radial gas foil bearing of the present invention;

[0022] Figure 2 This is a front view of the radial gas foil bearing of the present invention;

[0023] Figure 3This is a partial view of the assembly of the inner and outer wave foils of the radial gas foil bearing of the present invention;

[0024] Figure 4 This is a perspective view of the bearing sleeve of the present invention;

[0025] Figure 5 This is a perspective view of the external wave foil of the present invention;

[0026] Figure 6 This is a perspective view of the internal wave foil of the present invention;

[0027] Figure 7 This is a perspective view of the top foil of the present invention;

[0028] Figure 8 This is a front view of the top foil sheet of the present invention;

[0029] Figure 9 This is a partial view of the microtexture of the top foil sheet of the present invention.

[0030] In the diagram: 1 bearing sleeve, 2 outer corrugated foil, 3 inner corrugated foil, 4 top foil, 5 limiting groove, 6 micro-dimples, 7 micro-grooves. Detailed Implementation

[0031] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. The described embodiments are only preferred embodiments of the present invention and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without departing from the core innovative structure of the present invention and without creative effort are within the protection scope of the present invention.

[0032] Example 1: Combination Figure 1 and Figure 2 To illustrate this embodiment, this embodiment designs a double-wave foil nested gas wave foil bearing, including a bearing sleeve (1), an outer wave foil (2), an inner wave foil (3), and a top foil (4). The bearing sleeve (1), outer wave foil (2), inner wave foil (3), and top foil (4) are arranged sequentially from the outside to the inside. The outer wave foil (2) is fixed in the limiting groove (5) of the bearing sleeve (1). The inner wave foil (3) is nested inside the outer wave foil (2), and the top foil (4) is arranged inside the inner wave foil (3). The outer wave foil (2) and the inner wave foil (3) are both wavy elastic foils, and their wave arches are arranged one-to-one in the circumference of the bearing.

[0033] The outer wave foil (2) has a circular arc contact section at the top of the wave arch. The circular arc contact section has the same curvature as the inner circumferential surface of the bearing sleeve (1) to achieve surface contact and fit. The bottom of the outer wave foil (2) wave arch is a pointed arch support section, and the top of the pointed arch abuts against the top of the inner arc surface of the inner wave foil (3) wave arch.

[0034] The inner wave foil (3) has a circular arc contact section at the bottom of the wave arch. The circular arc contact section has the same curvature as the outer peripheral surface of the top foil (4) to achieve surface contact and fit. The top of the inner wave foil (3) wave arch is a pointed arch support section. The top of the pointed arch abuts against the bottom of the inner circular arc surface of the outer wave foil (2) wave arch, forming a bidirectional mutually supporting limiting structure.

[0035] The pointed arch structure where the inner and outer corrugated foils abut against each other forms a two-way limit, which can prevent the corrugated foils from slipping and twisting under load, ensuring uniform and stable support stiffness. Relying on the height difference of the corrugated arches of the two corrugated foils, only the inner corrugated foil (3) undergoes elastic deformation under low-speed start-stop and light-load conditions. The overall stiffness is low, and the friction damping generated by the multiple contact interfaces buffers vibration and avoids rigid rubbing. When entering high-speed heavy-load conditions, the deformation of the inner corrugated foil (3) tends to saturate, and the outer corrugated foil (2) deforms accordingly, and the overall support stiffness is increased synchronously. This resists air film vortex and rotor disturbance. The friction damping formed by the triple contact interfaces can also continuously dissipate vibration energy, further improving the stability and service life of the bearing under all operating conditions.

[0036] Preferably, as shown in the figure, the outer wave foil (2) and the inner wave foil (3) have the same number of wave arches and circumferential period, and the central axis of the wave arches coincides without any circumferential offset.

[0037] Optionally, the arc length of the contact section of the outer wave foil (2) is 1 / 3 to 1 / 2 of the circumferential length of the single wave arch, and the arc length of the contact section of the inner wave foil (3) is 1 / 3 to 1 / 2 of the circumferential length of the single wave arch.

[0038] Optionally, the apex angle of the pointed arch support section of the outer wave foil (2) and the inner wave foil (3) is 90°~150°, and the end of the pointed arch is treated with rounded corner transition.

[0039] In this embodiment, the inner surface of the top foil (4) is provided with a pit-groove composite microtexture. The composite microtexture includes multiple rows of circular micro-pits (6) evenly distributed along the circumference of the top foil. All circular micro-pits (4) on the same axial column are interconnected by axial micro-grooves (7) to form an integrally connected gas storage and flow guiding structure. The aperture and depth of the micro-pits (6) and the width, depth and spacing of the micro-grooves (7) can be adaptively matched according to the overall bearing specifications, operating speed, load requirements and lubrication stability requirements, and can be flexibly adapted to different working conditions.

[0040] During the bearing start-up and shutdown phase, the composite microtexture can store a small amount of gas medium using circular micro-dimples (6), forming a micro air cushion buffer layer between the journal and the surface of the top foil (4). During the high-speed operation phase of the bearing, the interconnected axial micro-grooves (7) can uniformly guide the airflow distribution, optimize the distribution of the gas film pressure field in the circumferential and axial directions of the bearing, and improve the uniformity and load-bearing capacity of the dynamic pressure gas film. At the same time, the airflow disturbance dissipation effect of the microtexture can increase the gas film damping, further suppressing the gas film eddy and rotor micro-vibration under high-speed conditions. Together with the double-wave foil nested damping structure, it forms a dual vibration reduction system of mechanical damping plus gas film damping, which greatly improves the high-speed operation stability and service life of the bearing.

[0041] The composite microtexture of the top foil sheet described in this invention can be prepared using existing mature precision processing methods, including laser etching, micro-milling, electrochemical etching, or imprinting. The processing methods are flexible, the processes are mature, and mass production is possible. Those skilled in the art can reasonably select the processing technology according to the processing accuracy requirements, production costs, and surface roughness requirements, without limiting to a single processing method, and without affecting the protection scope of the overall structure.

[0042] The assembly process in this example is as follows: Figure 1 , Figure 4 , Figure 5 , Figure 6 and Figure 7 As shown, first, the outer wave foil (2) is laid flat and attached to the inner wall of the bearing sleeve (1), aligned with the circumferential reference, and fixed by spot welding at both ends. Then, the inner wave foil (3) is nested inside the outer wave foil (2), the alignment accuracy of the wave arch is calibrated, and the central axes of the inner and outer wave arches are coincident and the pointed arches are accurately abutted. Then, the two ends of the inner wave foil (3) are spot welded and fixed. Finally, the top foil (4) is attached to the inner wall of the inner wave foil (3) to complete the overall assembly.

Claims

1. A double-wave foil nested support structure and textured top foil structure for a gas foil bearing, comprising a bearing sleeve (1), a cylindrical top foil sheet (4), and a cylindrical elastic wave foil assembly, wherein the elastic wave foil assembly is disposed between the bearing sleeve (1) and the top foil sheet (4), characterized in that: The elastic corrugated foil assembly is composed of an outer corrugated foil (2) and an inner corrugated foil (3) nested and stacked along the radial direction of the bearing, with their corrugations arranged one-to-one along the circumference of the bearing; the top of the corrugation of the outer corrugated foil (2) is provided with an arc-shaped contact section that matches the curvature of the inner circumferential surface of the bearing sleeve (1), and this arc-shaped contact section forms a surface contact support with the inner circumferential surface of the bearing sleeve (1); the top of the corrugation of the inner corrugated foil (3) is a pointed arch support section, the apex of which abuts against the bottom of the arc-shaped surface inside the corrugation of the outer corrugated foil (2), providing radial support for the arc-shaped contact section of the outer corrugated foil (2); the inner corrugated foil ( The bottom of the 3) wave arch is provided with an arc surface contact section that matches the curvature of the outer peripheral surface of the top foil (4). The arc surface contact section forms a surface contact support with the outer peripheral surface of the top foil (4). The bottom of the wave arch of the outer wave foil (2) is a pointed arch support section, the apex of which abuts against the top of the arc surface inside the wave arch of the inner wave foil (3), providing radial support for the arc surface contact section of the inner wave foil (3). The inner surface of the top foil (4) is evenly distributed with several circular pits (6) along the circumferential direction. The circular pits in the same row are connected by axial micro-grooves (7) to form a gas storage and flow guiding surface texture.

2. The double-wave foil nested support structure of the gas foil bearing according to claim 1, characterized in that: The outer wave foil (2) and the inner wave foil (3) have the same wave arch period, wave number and wave amplitude, and their wave arch center axes coincide, forming a one-to-one nested support relationship; the number n of the outer wave foil (2) and the inner wave foil (3) can be adapted to the actual working conditions of the bearing.

3. The double-wave foil nested support structure of the gas foil bearing according to claim 1, characterized in that: The arc length of the outer wave foil (2) is 1 / 3 to 1 / 2 of the circumferential length of the wave arch, and the arc length of the inner wave foil (3) is 1 / 3 to 1 / 2 of the circumferential length of the wave arch. The parameters of the arc length of the arc contact section can also be designed according to the actual working conditions.

4. The double-wave foil nested support structure of the gas foil bearing according to claim 1, characterized in that: The apex angle of the pointed arch support section of the outer wave foil (2) and the inner wave foil (3) is 90°~150°, and the parameters of the apex angle of the pointed arch support section can also be designed according to the actual working conditions.

5. The double-wave foil nested support structure of the gas foil bearing according to claim 1, characterized in that: The crown height of the outer wave foil (2) is greater than that of the inner wave foil (3), thereby achieving graded stiffness adjustment of the bearing support structure.

6. The double-wave foil nested support structure of the gas foil bearing according to claim 1, characterized in that: The outer wave foil (2) and the inner wave foil (3) are fixed to the inside of the limiting groove (5) of the bearing sleeve (1) by spot welding or riveting at both ends, which restricts the circumferential sliding of the wave foil and ensures the stability of the nested support structure.

7. The double-wave foil nested support structure of the gas foil bearing according to claim 1, characterized in that: The surface contact interface between the outer wave foil (2) and the bearing sleeve (1), the surface contact interface between the inner wave foil (3) and the top foil (4), and the contact interface between the outer wave foil (2) and the inner wave foil (3) together constitute a triple friction damping interface, which improves the vibration reduction and energy dissipation performance of the bearing.

8. The textured top foil structure of the gas wave foil bearing according to claim 1, characterized in that: The inner surface of the top foil (4) is provided with a pit-groove composite microtexture, which includes multiple rows of circular micro-pits (6) evenly distributed along the circumferential direction. The circular micro-pits (6) in the same axial row are interconnected by axial micro-grooves (7) to form a gas storage and flow guiding surface texture.

9. The textured top foil structure of the gas wave foil bearing according to claim 1, characterized in that: The diameter, depth, circumferential and axial spacing of the circular micro-pits (6) on the inner surface of the top foil (4), as well as the width and depth of the axial micro-grooves (7), can be adaptively matched and adjusted according to the bearing specifications, operating speed, load size and lubrication and vibration reduction requirements.

10. A gas-bearing foil bearing, characterized in that: It includes the double-wave foil nested support structure and the textured top foil structure as described in any one of claims 1-9.

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