Floating ring aerodynamic gas radial bearing

Abstract

The application discloses a floating ring gas dynamic pressure radial bearing, which comprises a bearing seat, a wave foil, a floating ring, a limiting ring and a shaft. The shaft is installed in the floating ring and can rotate freely, and the inner circular surface of the floating ring and the shaft form a friction pair. The wave foil is fixed between the bearing seat and the floating ring, and the floating ring is uniformly provided with floating ring openings. The flexible top foil of the conventional gas dynamic pressure bearing is replaced by the rigid floating ring, and the bearing seat, the wave foil, the floating ring and the limiting ring form a composite structure. The new overall structure of the floating ring bearing determines that the floating ring bearing has greater bearing capacity than the flexible top foil bearing, the material and coating of the floating ring determine the temperature resistance level, and through structure improvement and material adaptation, the gas wave foil bearing with high bearing capacity and high temperature resistance can be developed under the current technology and material development level, so that the gas dynamic pressure bearing is facilitated to be popularized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bearings, in particular to a floating ring gas dynamic pressure radial bearing. BACKGROUND

[0002] Turbomachinery is widely used in the energy, aviation, transportation, metallurgy, water treatment and refrigeration and low temperature industries. The power density and efficiency of turbomachinery increase significantly with the increase of rotational speed, and the volume and weight decrease significantly, which promotes the development of turbomachinery towards high rotational speed. With the increase of rotational speed of turbomachinery, the linear speed of the rotor and the DN value of the bearing also increase. The DN value refers to the product of the inner diameter of the bearing and the rotational speed of the shaft. If the DN value is too high, the existing rolling bearings and ordinary sliding bearings are difficult to meet the requirements. In order to solve this problem, gas foil bearings based on fluid dynamic pressure principle have emerged, which can meet the requirements of higher DN value. The gas foil bearing uses air or other gas as lubricating medium, and has the advantages of light structure, oil-free lubrication, smooth rotation and long service life compared with traditional sliding bearings and rolling bearings. However, due to the low viscosity of gas, the carrying capacity and system damping of gas dynamic pressure bearing are much lower than those of liquid dynamic pressure bearing, and there are gas film vortex and oscillation.

[0003] The radial foil dynamic pressure air bearing with thick top layer foil structure of application No. CN207906295U greatly increases the stiffness of the flat foil by increasing the thickness of the top foil from the conventional 0.1-0.2mm to 0.5-3mm, reduces the gas leakage at the end, and helps to solve the problem of top foil depression under heavy load and impact load, and can improve the carrying capacity to a certain extent. However, this patent still has some deficiencies, for example, the opening in the thick top layer destroys the integrity in the circumferential direction, the carrying capacity in the opening direction is greatly reduced due to gas leakage, and the coating cannot withstand a temperature higher than 300℃, which cannot adapt to high temperature and heavy load application occasions. Therefore, it is necessary to design and develop a floating ring gas dynamic pressure radial bearing to solve the above-mentioned problems and better meet the use requirements. SUMMARY

[0004] The present application aims to provide a floating ring gas dynamic pressure radial bearing to solve the problems of difficult to meet high DN value, low carrying capacity and insufficient temperature resistance level in the background art.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a floating ring gas dynamic pressure radial bearing, comprising a bearing seat, a wave foil, a floating ring and a shaft, the shaft is fixed inside the bearing seat, the floating ring is arranged outside the shaft, and the floating ring is uniformly provided with a floating ring opening, the wave foil is arranged outside the floating ring, and the bearing seat is provided with a limiting ring matched with the wave foil and the floating ring.

[0006] Preferably, the edge of the bearing seat is uniformly provided with threaded reserved holes, facilitating the user to assemble the bearing seat.

[0007] Preferably, the wave foil is in a wave shape, and the wave foil is in a pressed forming structure, so that the wave foil is convenient to process.

[0008] Preferably, the floating ring apertures are arranged at equal angles on the floating ring, so that the performance of the floating ring is improved.

[0009] Preferably, the two ends of the two sides of the floating ring extend out of the bearing seat by a certain length, the inner diameter of the limiting ring is equal to or slightly larger than the inner diameter of the bearing seat, and the outer diameter of the main body of the limiting ring is smaller than the outer diameter of the bearing seat, so that the axial movement of the floating ring and the wave foil can be limited.

[0010] Preferably, the shaft is made of high-strength alloy material, so as to ensure the structural strength and rigidity of the shaft.

[0011] Preferably, the neck part of the shaft is provided with a high-hardness and high-wear-resistance coating, so as to obtain a surface with high hardness, high wear resistance and low friction coefficient.

[0012] Preferably, fastening screws or rivets are uniformly arranged between the limiting ring and the bearing seat, so that the assembly of the limiting ring is facilitated.

[0013] Compared with the prior art, the present application has the following beneficial effects:

[0014] (1) The present application replaces the flexible top foil of the conventional gas dynamic pressure bearing with a rigid floating ring, and the bearing seat, the wave foil, the floating ring and the limiting ring are combined into a composite structure. The new overall structure of the floating ring bearing determines that it naturally has greater carrying capacity than the flexible top foil bearing, and the material and coating of the floating ring determine the level of temperature resistance. Furthermore, through structural improvement and material adaptation, a gas wave foil bearing with high carrying capacity and high temperature resistance is developed under the current technical and material development level, which facilitates the popularization of the gas dynamic pressure bearing.

[0015] (2) The floating ring gas dynamic pressure radial bearing is installed with a floating ring, a bearing seat and a wave foil. When in use, since the floating ring is a whole ring, it is easy to rotate during start and stop. In order to limit the axial movement of the floating ring and the wave foil, a limiting mechanism, i.e. a limiting ring, is needed in cooperation with the structure design of the floating ring. The floating ring extends out of the bearing seat by a length of 1 / 10-1 / 20 of the outer diameter of the floating ring, generally 2-6 mm, and 2-6 semicircular floating ring apertures with a diameter of 2-6 mm are uniformly arranged at the position close to the outer diameter of the end surface of the floating ring. The depth of the floating ring apertures is consistent with the length of the floating ring extending out. The limiting ring can be a whole ring with protrusions, and the shape and number of the protrusions correspond to the floating ring apertures. The limiting ring can also be formed by fastening a plurality of separate limiting blocks with the bearing seat, and the shape and number of the limiting blocks correspond to the floating ring apertures.

[0016] (3), the floating ring gas dynamic pressure radial bearing is installed with the floating ring and the high hardness high wear resistant coating, so that in specific operation, on the one hand, due to the top foil structure of the conventional gas foil bearing being innovatively arranged as a rigid floating ring, the circumferential stress is basically the same, therefore, the shape distribution of the wave foil does not have to be processed in the radial and axial zones to form different positions corresponding to different stiffness, and the wave foil can be directly formed according to the uniform wave shape, which is convenient for processing. And the wave foil still uses conventional materials and heat treatment methods, such as beryllium bronze and high-temperature nickel-based alloy. On the other hand, the shaft is made of high-strength alloy material, which can be solid and hollow, and meets the structural strength, and the surface is provided with a high hardness high wear resistant coating, that is, carburizing, nitriding, boronizing, permeation and other treatments or chrome plating and chrome oxide treatment, which can obtain a high hardness high wear resistant surface and a low friction coefficient, and form a wear resistant and wear reducing friction pair with the floating ring, thereby enhancing the practicability. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a front view of the partial cross-sectional structure of the present application;

[0018] Figure 2 It is a side view of the structure of the present application;

[0019] Figure 3 It is a schematic diagram of the three-dimensional half-section structure of the present application;

[0020] Figure 4 It is a front view of the cross-sectional structure of the floating ring of the present application;

[0021] Figure 5 It is a schematic diagram of the cross-sectional structure of the side wall of the shaft of the present application.

[0022] In the figure: 1, fastening screw or rivet; 2, bearing seat; 3, wave foil; 4, floating ring aperture; 5, floating ring; 6, shaft; 7, limiting ring; 8, threaded reserved hole; 9, high hardness high wear resistant coating; 10, high-strength alloy material. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0024] Please refer to Figures 1-5 , the present application provides an embodiment: a floating ring gas dynamic pressure radial bearing, comprising a bearing seat 2, a wave foil 3, a floating ring 5 and a shaft 6, the shaft 6 is fixed in the inside of the bearing seat 2;

[0025] The floating ring 5 is arranged outside the shaft 6, and the floating ring 5 is uniformly provided with floating ring apertures 4;

[0026] The wave foil 3 is arranged between the floating ring 5 and the bearing seat 2, and the bearing seat 2 is provided with a limiting ring 7 matched with the wave foil 3 and the floating ring 5;

[0027] The edge of the bearing seat 2 is uniformly provided with threaded reserved holes 8, so that the bearing seat 2 is assembled by the threaded reserved holes 8;

[0028] The wave foil 3 is in a wave shape, and the wave foil 3 is in a pressed forming structure;

[0029] In use, the top foil structure of the conventional gas foil bearing is innovatively arranged as the rigid floating ring 5, and the circumferential stress is basically the same, so the shape distribution of the wave foil 3 does not need to be processed in different positions in the radial and axial directions to form different rigidities, and the wave foil 3 can be directly pressed and formed in a uniform wave shape, which is convenient for processing, and the wave foil 3 also uses the conventional materials and heat treatment methods, such as beryllium bronze and high-temperature nickel-based alloy;

[0030] The floating ring openings 4 are arranged in 2-6, and adjacent floating ring openings 4 are symmetrically distributed about the center line of the floating ring 5;

[0031] In use, the material of the floating ring 20 mainly includes the following two types: first, a metal or ceramic surface is coated, and the coating includes modified PTFE, MoS2, WS2, graphite, chromium plating, chromium oxide, titanium carbide, titanium nitride, titanium aluminum nitride, titanium silicon carbide, diamond-like film DLC and diamond film, and composite coatings such as CaF2 / Ag, Ti / Ni, Pb-Ag-Cu-Re, WC-Co-Cu-BaF2-CaF2 and other solid lubricating materials. Second, low-friction coefficient materials such as hard alloy, various metal, babbitt alloy, glass and resin impregnated carbon graphite, glass carbon, siliconized graphite, fluorinated graphite, silicon carbide and silicon nitride and their composite materials, carbon / carbon composite materials, titanium silicon carbide or its composite materials. Among them, hard alloy, titanium silicon carbide, silicon carbide and silicon nitride and their composite ceramics can withstand high temperatures of more than 1000℃, and after surface treatment, a lower friction coefficient can be obtained, and the surface can be processed to a high surface finish, so it can be applied to 600-800℃. Considering the difference in thermal expansion coefficient, a transition coating needs to be made on the metal matrix, and silver impregnated carbon graphite has a low wear coefficient and can also work normally at 900℃, so it can also be applied at 600-800℃. Of course, copper impregnated carbon graphite, carbon / carbon composite materials and carbon / silicon carbide composite materials can also work at 600-800℃ after surface oxidation prevention treatment;

[0032] The two sides of the floating ring 5 extend out of the bearing seat 2 by a certain length, the inner diameter of the limiting ring 7 is equal to or slightly larger than the inner diameter of the bearing seat 2, and the outer diameter of the limiting ring 7 is smaller than the outer diameter of the bearing seat 2;

[0033] In use, the floating ring 5 extends out of the bearing seat 2 on both sides, with a length of 1 / 10-1 / 20 of the outer diameter of the floating ring 5, generally 2-6 mm, and 2-6 semicircular floating ring openings 4 are evenly distributed near the outer diameter at the end surface of the floating ring 5, with a diameter of 2-6 mm and a depth consistent with the length of the floating ring 5 extending out. Since the floating ring 5 is a whole ring, it is easy to rotate when starting and stopping. In order to limit the axial movement of the floating ring 5 and the wave foil 3, a limiting mechanism, i.e. a limiting ring 7, is needed. The structure of the limiting ring 7 can be a whole ring with protrusions or a structure formed by evenly arranging multiple separate limiting blocks, so that the limiting structure has high flexibility.

[0034] The shaft 6 is made of high-strength alloy material 10.

[0035] The shaft neck part of the shaft 6 is provided with a high-hardness and high-wear-resistant coating 9.

[0036] In use, the shaft 6 is made of high-strength alloy material, which can be solid or hollow, and meets the structural strength requirements. The surface is provided with a high-hardness and high-wear-resistant coating 9, i.e. carburizing, nitriding, boronizing, chromium plating, and oxidation chromium treatment, etc. This can obtain a high-hardness and high-wear-resistant shaft neck surface with a low friction coefficient, which forms a wear-resistant and wear-reducing friction pair with the floating ring 5.

[0037] Fastening screws or rivets 1 are evenly installed between the limiting ring 7 and the bearing seat 2.

[0038] In use, the limiting ring 7 is fixed on the bearing seat 2 by the fastening rivets or screws 1 for limiting the floating ring 5 and the wave foil 3.

[0039] In use, the composite structure composed of the bearing seat 2, the wave foil 3, the floating ring 5, and the limiting ring 7 optimizes the performance of the bearing. The new overall structure of the floating ring bearing determines that it naturally has greater carrying capacity than the flexible top foil bearing. The material and coating of the floating ring 5 determine the level of temperature resistance. The specific processing scheme is as follows:

[0040] I. The shaft 6 is made of high-temperature nickel-based alloy. The shaft neck surface is first processed with a hard alloy transition coating and then coated with silicon carbide. The surface is finely ground to Ra≤0.1. The floating ring 5 is silver-immersed carbon graphite. The wave foil 3 is pre-tightened and installed. The friction coefficient can be lower than 0.15, and the temperature resistance can be ≥900℃.

[0041] II. The shaft 6 is made of high-temperature nickel-based alloy. The shaft neck surface is first processed with a hard alloy transition coating and then coated with silicon carbide. The surface is finely ground to Ra≤0.1. The floating ring 5 is glass-immersed carbon graphite with an anti-oxidation coating. The wave foil 3 is pre-tightened and installed. The friction coefficient can be lower than 0.15, and the temperature resistance can be ≥900℃.

[0042] Three, the shaft 6 uses high temperature nickel base alloy, the shaft neck surface first processes hard alloy transition coating and then does silicon carbide coating, the surface is precisely ground to Ra≤0.1, the floating ring 5 is glass carbon, the wave foil 3 is pre-tightened and installed, the friction coefficient can be less than 0.15, and the temperature resistance can be ≥700 DEG C.

[0043] Four, the shaft 6 uses high temperature nickel base alloy, the shaft neck surface first processes hard alloy transition coating and then does silicon carbide coating, the surface is precisely ground to Ra≤0.1, the floating ring 5 is carbon / silicon carbide composite material, the wave foil 3 is pre-tightened and installed, the friction coefficient is less than 0.2, and the temperature resistance can be ≥900 DEG C.

[0044] Five, the shaft 6 uses high temperature nickel base alloy, the shaft neck surface first processes hard alloy transition coating and then does silicon carbide coating, the surface is precisely ground to Ra≤0.1, the floating ring 5 is carbon / carbon composite material, the inner surface is coated with SiC, the wave foil 3 is pre-tightened and installed, the friction coefficient is less than 0.2, and the temperature resistance can be ≥900 DEG C.

[0045] Six, the shaft 6 uses high temperature nickel base alloy, the shaft neck surface first processes hard alloy transition coating and then does silicon carbide coating, the surface is precisely ground to Ra≤0.1, the floating ring 5 is high temperature nickel base alloy after nitriding, carburizing, boronizing and sulfurizing treatment and then coated with titanium nitride silicon, the friction coefficient is less than 0.3, and the temperature resistance can be ≥900 DEG C.

[0046] Seven, the shaft 6 uses high temperature nickel base alloy, the shaft neck surface first processes hard alloy transition coating and then does silicon carbide coating, the surface is precisely ground to Ra≤0.1, the floating ring 5 is heat-resistant stainless steel after nitriding, carburizing, boronizing and sulfurizing treatment and then plated with chromium or chromium oxide, the friction coefficient is less than 0.3, and the temperature resistance can be ≥900 DEG C.

[0047] Eight, the shaft 6 uses high temperature nickel base alloy, the shaft neck surface first processes hard alloy transition coating and then does silicon carbide coating, the surface is precisely ground to Ra≤0.1, the floating ring is titanium silicon carbide Ti3SiC2 or its composite material, and the wave foil is pre-tightened and installed, the friction coefficient can be less than 0.2, and the temperature resistance can be ≥900 DEG C.

[0048] The processing scheme is selected according to actual requirements, and since the top foil structure of the conventional gas foil bearing is innovatively arranged as the rigid floating ring 5, the circumferential stress is basically the same, therefore the shape distribution of the wave foil 3 does not have to be processed in the radial and axial zones to form different positions corresponding to different stiffnesses as in the second and third generation gas wave foil bearings, and the wave foil 3 can be directly pressed into shape according to the uniform wave shape, which is convenient for processing, and the wave foil 3 still uses conventional materials and heat treatment methods, such as beryllium bronze and high temperature nickel base alloy.

[0049] Furthermore, since the floating ring is a whole ring, it is easy to rotate at start and stop, and in order to limit the axial movement of the floating ring and the wave foil, a limiting mechanism, i.e. a limiting ring, needs to be matched with the structure design of the floating ring. The bearing seat is extended on both sides of the floating ring, the length is 1 / 10-1 / 20 of the outer diameter of the floating ring, generally 2-6mm, and 2-6 semicircular floating ring openings are uniformly distributed near the outer diameter of the end surface of the floating ring, with a diameter of 2-6mm and a depth consistent with the length of the floating ring extension. The limiting ring can be a whole ring with protrusions, and the shape and number of the protrusions correspond to the floating ring openings. The limiting ring can also be formed by fastening a plurality of separate limiting blocks with the bearing seat, and the shape and number of the limiting blocks correspond to the floating ring openings.

Claims

1. A floating ring aerodynamic gas radial bearing, characterized in that, Including bearing seat (2), wave foil (3), floating ring (5) and shaft (6), the shaft (6) is located in the inside of floating ring (5), floating ring (5) thickness is 2-6mm and the whole is rigid circular ring structure, and the floating ring (5) is uniformly provided with floating ring aperture (4), the wave foil (3) is arranged between bearing seat (2) and floating ring (5), the bearing seat (2) is installed with the limiting ring (7) matched with wave foil (3) and floating ring (5); The both sides of bearing seat (2) are uniformly provided with threaded reserved hole (8), the wave foil (3) is wave-shaped, the wave foil (3) is a pressed forming structure, the floating ring aperture (4) is arranged at equal angles on floating ring (5), the both sides of floating ring (5) are extended out of bearing seat (2) by a certain length and are provided with apertures, the inner diameter of limiting ring (7) body is equal to or slightly larger than the inner diameter of bearing seat (2), the outer diameter of limiting ring (7) is smaller than the outer diameter of bearing seat (2), the shaft (6) is high-strength alloy material (10), solid or hollow structure, the shaft neck part of shaft (6) is provided with high-hardness high-wear-resistant coating (9), the limiting ring (7) and bearing seat (2) are uniformly provided with fastening screws or rivets (1) between them; The shaft (6) cooperates with floating ring (5) to form a wear-resistant and friction-reducing friction pair, the friction coefficient of the friction pair is less than 0.3, the material treatment method of floating ring (5) is to use low-friction coefficient material impregnated composite material, the low-friction coefficient material impregnated composite material is selected from any one of the following materials: silver-impregnated carbon graphite, glass-impregnated carbon graphite, the outer surface of the glass-impregnated carbon graphite is provided with an oxidation-resistant coating, glass carbon, carbon / silicon carbide composite material, carbon / carbon composite material, the inner surface of the carbon / carbon composite material is provided with a SiC coating, high-temperature nickel-based alloy, the high-temperature nickel-based alloy is first treated by nitriding, carburizing, boronizing and sulfurizing, and then a titanium silicon nitride coating is processed, heat-resistant stainless steel, the heat-resistant stainless steel is first treated by nitriding, carburizing, boronizing and sulfurizing, and then chromium plating or chromium oxide plating is carried out, titanium silicon carbide or its composite material; The material of shaft (6) is high-strength alloy material, the high-strength alloy material is high-temperature nickel-based alloy, the high-hardness high-wear-resistant coating (9) treatment method is to process a hard alloy transition coating on the surface of shaft neck first and then process a silicon carbide coating.

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