Radial air bearing filled with special-shaped foil

Abstract

The invention belongs to the field of foil gas dynamic pressure bearings, and relates to a radial air bearing filled with special-shaped foils. Comprising a top-layer flat foil, a bump foil, a middle bottom foil, a middle flat foil, a rectangular bottom foil and a bearing seat, the etching grooves in the inner surface of the top-layer flat foil can reduce the contact area of the rotor and the bearing during starting, the floating moment or the floating rotating speed of a product can be reduced, and the narrow pieces on the outer surface can reduce the axial end leakage of gas, so that the bearing performance of the bearing is enhanced; the bump foil provides multi-stage structural rigidity, the large wave arch arches main support in light load, the large wave arch deforms in heavy load, and the small wave arch also provides certain support; the triangular or trapezoidal bump foil can avoid bearing failure caused by permanent plastic deformation of the wave arch under the condition of larger vibration impact; the mounting clearance of the radial air bearing can be adjusted by changing the number of the middle flat foils of the shutter structure; the staggered raised rectangular bottom foil ensures that the bearing has certain elastic support when the bearing is subjected to large vibration impact, so that the ultimate bearing performance of the bearing is improved.

Description

Technical Field

[0001] The invention belongs to the field of foil gas dynamic pressure bearings and relates to a radial air bearing filled with special-shaped foils. Background Art

[0002] With the development of the national economy, turbomachinery, which is widely used in industries such as industry and national defense, is developing towards high speed, high power and high energy density, which puts higher and higher requirements on the stable and reliable operation of supporting components. At the same time, bearing performance also restricts my country's progress in the fields of aviation, aerospace, and new energy. For example, the speed of a micro turboshaft generator is usually as high as 150-200krpm, and the operating temperature is 400-500℃, which puts forward stringent design and use requirements for bearings. Traditional rolling bearings are difficult to adapt to such working conditions, and the accompanying lubrication and cooling system is not conducive to the weight and reliability of the whole machine. As a type of flexible gas bearing, foil dynamic pressure bearings have great application value in equipment such as aviation airborne air compressors, small gas power stations, micro ultra-high-speed fans, and aviation turbine coolers.

[0003] Compared with ordinary rigid bearings, the introduction of elastic foil makes it have many characteristics such as simple structure, good stability, high limit speed, high temperature resistance, impact resistance, long life, excellent start-stop performance, etc., and the installation accuracy requirements are relatively low, and the tolerance to rotor thermal / centrifugal expansion is also greatly improved. In addition, the friction damping between the foils consumes part of the energy of the bearing-rotor system, which can effectively suppress its high and low frequency vortex, and increase the reliability and stability of the system. For decades, foil bearings have received extensive attention and research, and are an ideal choice for future medium / low power, high speed / ultra-high speed turbomachinery supports.

[0004] The structure of the conventional radial foil gas dynamic bearing is as follows: Figure 1 As shown, it mainly includes bearing sleeves, corrugated foils, flat foils, etc., and has the following shortcomings:

[0005] 1. The rigidity of a single-layer wave foil is limited. When the rotor is subjected to a sudden large radial impact, the wave arch is easily crushed and deformed and cannot rebound, resulting in increased bearing clearance and scratches on the rotor impeller;

[0006] 2. The structure of a single-layer flat foil plus a single-layer corrugated foil has poor Coulomb friction damping of the bearing and cannot effectively absorb environmental vibrations in the fields of aviation, new energy vehicles, etc.

[0007] 3. The radial bearing has poor adaptability to the load-bearing capacity and completely relies on changing the thickness or hardness of the foil to match the load-bearing capacity, resulting in a single radial bearing lacking the ability to autonomously adjust the load-bearing requirements in different usage scenarios;

[0008] 4. Rely on the gradient change of the wave arch height to achieve a local convergent wedge to improve the bearing capacity. This method has high processing accuracy for the mold, and the arch height changes after the wave foil is deformed by force, causing the shape of the prefabricated air film wedge to gradually deviate from the optimal design value.

[0009] 5. The gas leakage on both sides of the radial bearing is serious, which is not conducive to the internal pressure maintenance and stable bearing capacity improvement of the bearing;

[0010] 6. Lack of multi-layer preload structure to solve the installation deflection problem between radial bearing and rotor;

[0011] 7. Lack of clear cooling pore structure to solve the heating problem during the use of radial bearings;

[0012] 8. The overlapped radial bearing lacks an adjustable installation preload structure, the clamping torque of the foil on the shaft is generally not adjustable, and the adjustment and optimization of the start-stop performance is limited;

[0013] 9. There is no gap adjustment shim structure, and the installation clearance of the bearing can only be adjusted by repairing the bearing sleeve;

[0014] 10. There is surface contact between the flat foil surface and the rotor, resulting in a large starting torque for the product. Summary of the invention

[0015] Purpose of the Invention

[0016] Provided is a radial air bearing structure filled with special-shaped foils. The invention has the advantages of large structural damping, strong vibration and impact resistance, good self-adaptation, small starting torque, and adjustable preload and clearance.

[0017] Technical Solution

[0018] A radial air bearing filled with special-shaped foils comprises a top flat foil, a corrugated foil, an intermediate bottom foil, an intermediate flat foil, a rectangular bottom foil and a bearing seat; the top flat foil is an arc surface structure provided with a fixed end and a free end, a pre-tightening gasket is welded on the fixed end of the top flat foil, an etching groove is provided on the inner surface of the free end of the top flat foil, a narrow sheet is provided on the outer surface of the free end of the top flat foil, the corrugated foil is an arc surface structure provided with a fixed end and a free end, the free end of the corrugated foil is a large arc double-arch structure, and a cooling air hole is provided on the free end of the corrugated foil; the free end of the intermediate bottom foil is an arc surface structure, and the arc surface structure of the free end of the intermediate bottom foil is specifically composed of a plurality of triangles or trapezoids, and a depression is provided in the connecting area between two triangles or trapezoids, and the direction of the depression is the same as that of the triangle or trapezoid. The forming angles are in opposite directions; the intermediate flat foil is divided into a first intermediate flat foil and a second intermediate flat foil, both of which are provided with louver structures, and the directions of the louver structures on the first intermediate flat foil and the second intermediate flat foil are opposite, and the first intermediate flat foil and the second intermediate flat foil are nested as a whole through the louver structure; the inner and outer surfaces of the free end of the rectangular bottom foil are provided with crossed protrusions, and the protrusions on the upper surface of the free end of the rectangular bottom foil are provided with grooves and cooling air holes; the rectangular bottom foil, the intermediate flat foil, the corrugated foil, the intermediate bottom foil, and the top flat foil are sequentially assembled at the V-groove on the bearing seat through various fixed ends, and ensure that the nesting area on the intermediate flat foil corresponds to the protrusion on the lower surface of the rectangular bottom foil.

[0019] Furthermore, multiple layers of intermediate flat foils may be provided on the radial air bearing.

[0020] Furthermore, multiple layers of intermediate flat foils are stacked and assembled, and the installation clearance of the radial air bearing can be adjusted by changing the number of intermediate flat foils.

[0021] Furthermore, the top flat foil has an angle of 80 degrees and a thickness of 0.1 mm.

[0022] Furthermore, the depth of the etching groove is 0.015 mm.

[0023] Furthermore, the thickness of the preload gasket ranges from 0.05 mm to 0.15 mm.

[0024] Furthermore, the narrow sheet has a width of 2 mm and a thickness of 0.02 mm.

[0025] Furthermore, the corrugated foil has an angle of 58° and a thickness of 0.1 mm.

[0026] Furthermore, the thickness of the middle bottom foil is 0.08 mm, and the number and distribution of the triangles or trapezoids are consistent with the double arches on the corrugated foil.

[0027] Furthermore, the thickness of the protrusions on the rectangular bottom foil is 0.02 mm.

[0028] Furthermore, the protrusion is in the shape of a long strip and runs through the entire rectangular bottom foil in the thickness direction.

[0029] Furthermore, the materials of the top flat foil, corrugated foil, middle bottom foil, middle flat foil and rectangular bottom foil are all GH4169, and the material of the bearing seat is 7A02.

[0030] The beneficial effects of this application are:

[0031] The etched grooves 11 on the inner surface of the top flat foil 1 can reduce the contact area between the rotor and the bearing during startup, which is beneficial to reducing the buoyancy torque or buoyancy speed of the product. The narrow slices 13 on the outer surface can reduce the axial end leakage of the gas, thereby enhancing the bearing performance of the bearing; the wave foil 2 provides multi-level structural stiffness. When the load is light, the large wave arch is the main support. When the load is heavy, the large wave arch is deformed, and the small wave arch also provides certain support; the triangular or trapezoidal wave foil 3 can avoid the permanent plastic deformation of the wave arch under the condition of large vibration impact, resulting in bearing failure; changing the number of the middle flat foils 4 of the louver structure can adjust the installation clearance of the radial air bearing; the rectangular bottom foil 5 with staggered protrusions can ensure that the bearing has a certain elastic support when the bearing is subjected to a large vibration impact, thereby improving the ultimate bearing performance of the bearing; the multi-layer stacked foil can ensure that the bearing has good friction damping and can effectively absorb the vibration impact in the use environment. At the same time, each foil is provided with cooling air holes, which can effectively reduce the heating of the bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a traditional radial foil air bearing structure;

[0033] Figure 2 The overall assembly structure of the radial air bearing of the present invention;

[0034] Figure 3A Schematic diagram of the groove structure on the inner surface of the top flat foil

[0035] Figure 3B Schematic diagram of the outer surface structure of the top flat foil;

[0036] Figure 4A Schematic diagram of the corrugated foil structure;

[0037] Figure 4B Schematic diagram of the deformation of the corrugated foil structure;

[0038] Figure 5A Schematic diagram of the filled triangle bottom foil structure;

[0039] Figure 5B Schematic diagram of deformation of the filled triangle bottom foil;

[0040] Figure 5C Schematic diagram of the structure of the filled trapezoidal bottom foil;

[0041] Figure 5DSchematic diagram of deformation of filled trapezoidal bottom foil;

[0042] Fig. 6A A schematic diagram of the structure of the first intermediate flat foil;

[0043] Figure 6B A schematic diagram of the structure of the second intermediate flat foil;

[0044] Figure 7 Schematic diagram of the multi-layer intermediate flat foil combination structure.

[0045] Fig. 8A Schematic diagram of the filled rectangular bottom foil structure;

[0046] Figure 8B Schematic diagram of deformation of filled rectangular bottom foil;

[0047] Fig. 9 Schematic diagram of the bearing sleeve structure.

[0048] Fig.10 It is a working schematic diagram of the radial air bearing of the present invention;

[0049] Reference numerals: 1 - top flat foil, 2 - corrugated foil, 3 - filled triangular or trapezoidal bottom foil, 4 - middle flat foil, 5 - filled rectangular bottom foil, 6 - bearing sleeve, 7 - shaft. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical scheme and advantages of the implementation of the present invention clearer, the technical scheme in the embodiment of the present invention will be described in more detail in combination with the embodiment of the present invention. In the example, the same or similar reference numerals throughout represent the same or similar originals or elements with the same or similar functions. The described embodiments are part of the embodiments of the present invention, not all of them. The embodiments described below by reference are exemplary and intended to be used to explain the present invention, and should not be construed as limitations on the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present invention. The following is a detailed description in combination with the embodiments of the present invention.

[0051] A radial air bearing filled with special-shaped foils comprises a top flat foil 1, a corrugated foil 2, an intermediate bottom foil 3, an intermediate flat foil 4, a rectangular bottom foil 5 and a bearing seat 6; the top flat foil 1 is an arc surface structure provided with a fixed end and a free end, a pre-tightening gasket 12 is welded on the fixed end of the top flat foil 1, an etching groove 11 is provided on the inner surface of the free end of the top flat foil 1, a narrow sheet 13 is provided on the outer surface of the free end of the top flat foil 1, the corrugated foil 2 is an arc surface structure provided with a fixed end and a free end, the free end of the corrugated foil 2 is a large arc double-arch structure, and a cooling air hole is provided on the free end of the corrugated foil 2; the free end of the intermediate bottom foil 3 is an arc surface structure, and the arc surface structure of the free end of the intermediate bottom foil 3 is specifically composed of a plurality of triangles or trapezoids, and a depression is provided in the connecting area between two triangles or trapezoids, and the direction of the depression is the same as that of the three triangles or trapezoids. The angles of the angled or trapezoidal forming are in opposite directions; the intermediate flat foil 4 is divided into a first intermediate flat foil and a second intermediate flat foil, both of which are provided with a louver structure, and the directions of the louver structures on the first intermediate flat foil and the second intermediate flat foil are opposite, and the first intermediate flat foil and the second intermediate flat foil are nested as a whole through the louver structure; the inner and outer surfaces of the free end of the rectangular bottom foil 5 are provided with cross-staggered protrusions, and the protrusions on the upper surface of the free end of the rectangular bottom foil 5 are provided with grooves and cooling air holes; the rectangular bottom foil 5, the intermediate flat foil 4, the corrugated foil 2, the intermediate bottom foil 3, and the top flat foil 1 are sequentially assembled at the V-groove on the bearing seat 6 through various fixed ends, and ensure that the nesting area on the intermediate flat foil 4 corresponds to the protrusion on the lower surface of the rectangular bottom foil 5.

[0052] In a certain embodiment of the present invention, multiple layers of intermediate flat foils 4 may be provided on the radial air bearing.

[0053] In a certain implementation case of the present invention, multiple layers of intermediate flat foils 4 are stacked and assembled, and the installation clearance of the radial air bearing can be adjusted by changing the number of intermediate flat foils.

[0054] In one embodiment of the present invention, the top flat foil 1 has an angle of 80 degrees and a thickness of 0.1 mm. In one embodiment of the present invention, the depth of the etched groove 11 is 0.015 mm.

[0055] In a certain embodiment of the present invention, the thickness of the preload gasket 12 is in the range of 0.05 mm to 0.15 mm.

[0056] In one embodiment of the present invention, the narrow sheet 13 has a width of 2 mm and a thickness of 0.02 mm.

[0057] In a certain embodiment of the present invention, the corrugated foil 2 has an extension angle of 58° and a thickness of 0.1 mm.

[0058] In a certain embodiment of the present invention, the thickness of the middle bottom foil 3 is 0.08 mm, and the number and distribution of the triangles or trapezoids are consistent with the double arches on the corrugated foil 2 .

[0059] In one embodiment of the present invention, the thickness of the protrusion on the rectangular bottom foil 5 is 0.02 mm.

[0060] In a certain embodiment of the present invention, the protrusion is in the shape of a long strip, which runs through the entire rectangular bottom foil 5 in the thickness direction;

[0061] In a certain implementation case of the present invention, the top flat foil 1, the corrugated foil 2, the middle bottom foil 3, the middle flat foil 4, and the rectangular bottom foil 5 are all made of GH4169, and the bearing seat material is 7A02.

[0062] 1. The surface of the flat foil is etched with a special shape of etching groove 11 to reduce the contact area between the flat foil and the rotor during startup. No coating is sprayed on the micro-groove part.

[0063] 2. Rectangular narrow gaskets are welded on the bottom of both axial sides of the flat foil to reduce gas end leakage and improve the bearing capacity of the bearing.

[0064] 3. There are adjacent "multi-arch" structures on the wave foil, that is, there are no less than two small wave arches on each large wave arch. The combination of large and small wave arches can provide multi-level structural stiffness.

[0065] 4. Cooling holes are opened on the wave foil to increase adaptability and enhance cooling effect.

[0066] 5. The bottom of the corrugated foil is filled with a special-shaped bottom foil. The triangular or trapezoidal special-shaped arch is located at the bottom of the corrugated arch. The multi-arch structure is consistent with the corrugated foil and plays a role in supporting the corrugated foil.

[0067] 6. A layer of middle flat foil is arranged below the triangular or trapezoidal foil, and the surface of the middle flat foil is processed with evenly distributed warping holes to provide installation preload, enhance cooling and correct rotor deflection.

[0068] 7. The bottom of the middle flat foil is filled with a rectangular bottom foil, and the surface of the bottom foil has protrusions distributed at intervals up and down. It deforms under pressure and provides elastic support with a larger stiffness level. At the same time, the grooves of the rectangular foil adjust its stiffness.

[0069] 8. A preload gasket is welded at the fixed end of the top flat foil. By adjusting the thickness of the preload gasket and coordinating with the V-notch of the bearing sleeve, the installation preload force of the lap-jointed radial bearing can be changed to coordinate the load-bearing capacity and starting torque.

[0070] 9. The surfaces of rectangular foil, intermediate foil, filled special-shaped foil, corrugated foil, flat foil, etc. are processed with different forms of cooling holes to improve the heat dissipation of radial air bearings.

[0071] 10. Multiple layers of intermediate flat foils can be stacked and assembled, and the installation clearance of the radial air bearing can be adjusted by changing the number of intermediate flat foils.

[0072] Example 1

[0073] A radial air bearing filled with shaped foil, see Figure 2 to Figure 10 , including top flat foil, corrugated foil, filled triangle or trapezoidal bottom foil, middle flat foil, filled rectangular bottom foil, bearing sleeve, etc.

[0074] The bearing sleeve has 6 foil installation V-grooves evenly distributed along the circumferential direction. Each interface is a "V"-shaped groove. The narrowest width of the groove is 0.5mm, which is slightly larger than the total thickness of the 6 layers of foil.

[0075] Each top flat foil has an extension angle of 80 degrees and a thickness of 0.1 mm. On the side of the top flat foil in contact with the rotor, a herringbone groove is etched on the surface with a depth of 0.015 mm, and no coating is sprayed on the grooved portion.

[0076] At the bottom of the top flat foil, two gaskets are arranged on both sides of the axial direction by welding. The width of the gasket is 2mm and the thickness is 0.02mm. The welding process should be carried out before spraying and etching.

[0077] A gap adjustment gasket is welded to the fixed end of the top foil. The thickness of the gasket can be selected according to the required installation preload force, and the thickness range is between 0.05mm and 0.15mm.

[0078] The corrugated foil is located at the bottom of the top flat foil. Each corrugated foil has an extension angle of 58° and a thickness of 0.1 mm. There are two large wave arches, and each large wave arch is arranged with two small wave arches. The overall large curvature of the corrugated foil is consistent with the top flat foil.

[0079] The triangular or trapezoidal bottom foil is located below the corrugated foil and has a thickness of 0.08 mm. The number and distribution of the large and small special-shaped arches are consistent with the corrugated foil.

[0080] The thickness of the middle flat foil is 0.06mm, and it is partially processed with evenly distributed "louvers" that are raised up and down.

[0081] The filling rectangular foil is installed below the middle flat foil. The 0.12 mm thick foil has protrusions spaced above and below, and the thickness of each protrusion is 0.02 mm.

[0082] The material of all foils and gaskets is GH4169, the bearing seat material is 7A02, the welding is resistance welding, and the surface coating material of the top flat foil is Teflon.

[0083] Example 2

[0084] In some embodiments, a radial air bearing filled with a shaped foil has the following features compared to Embodiment 1:

[0085] Two sets of spiral grooves are etched on both sides of the top flat foil, with a groove depth of 0.02 mm.

[0086] A plurality of connected arches are evenly distributed on the wave foil, and the number of small wave arches in each connected arch is greater than 3. Under the action of pressure, the connected arches will deform into a large wave arch, so that the thrust bearing has adaptability.

[0087] The corrugated foil is processed with no less than 3 cooling air holes along the circumferential direction, so that the sliding deformation of each corrugated arch is more flexible and the cooling air flow inside the bearing is smoother.

[0088] The number of V-shaped grooves of the bearing sleeve is greater than 6, the corresponding multi-layer elastic foil has an extension angle less than 55 degrees, and the extension angle of the top flat foil is less than 80 degrees.

[0089] For the multi-arch structures of corrugated foil and filled triangular / trapezoidal foil, the number of large and small corrugated arches is greater than 3.

[0090] The number of the intermediate flat foils is not less than 2. When multiple layers of intermediate flat foils are stacked in reverse, the positions of the raised claws on one of the flat foils and the grooves on another flat foil are the same.

[0091] The materials of the multi-layer foil and the gasket are GH4145 or Inconcel X-750 or Inconcel X-718, and the thickness can be selected between 0.08 and 0.2 according to the use requirements.

[0092] The foil and the gasket are fixed by laser welding.

[0093] The top flat foil surface is coated with molybdenum disulfide or other composite wear-resistant and friction-reducing coatings.

[0094] The bearing sleeve material is 4Cr13 and other alloy steel.

[0095] It is understood by those skilled in the art that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as the general understanding of ordinary technicians in the field to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and unless defined as here, will not be interpreted with idealized or overly formal meanings. The specific implementation methods described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the present invention. Within the spirit and principle of the present invention, any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment of equivalent changes for application in other fields, but any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the technical solution content of the present invention, any modification, equivalent replacement, improvement, etc., made according to the technical essence of the present invention, should be included in the protection scope of the present invention.

Claims

1. A radial air bearing filled with a special-shaped foil, characterized in that: It comprises a top flat foil, a corrugated foil, an intermediate bottom foil, an intermediate flat foil, a rectangular bottom foil and a bearing seat; the top flat foil is an arc surface structure provided with a fixed end and a free end, a pre-tightening gasket is welded on the fixed end of the top flat foil, an etching groove is provided on the inner surface of the free end of the top flat foil, a narrow sheet is provided on the outer surface of the free end of the top flat foil, the corrugated foil is an arc surface structure provided with a fixed end and a free end, the free end of the corrugated foil is a large arc double-arch structure, and a cooling air hole is provided on the free end of the corrugated foil; the free end of the intermediate bottom foil is an arc surface structure, and the arc surface structure of the free end of the intermediate bottom foil is specifically composed of a plurality of triangles or trapezoids, and a depression is provided in the connecting area between two triangles or trapezoids, and the direction of the depression is opposite to the direction of the forming angle of the triangle or trapezoid The middle flat foil is divided into a first middle flat foil and a second middle flat foil, both of which are provided with a louver structure, and the directions of the louver structures on the first middle flat foil and the second middle flat foil are opposite, and the first middle flat foil and the second middle flat foil are nested as a whole through the louver structure; the inner and outer surfaces of the free end of the rectangular bottom foil are provided with crossed protrusions, and the protrusions on the upper surface of the free end of the rectangular bottom foil are provided with grooves and cooling air holes; the rectangular bottom foil, the middle flat foil, the corrugated foil, the middle bottom foil, and the top flat foil are sequentially assembled at the V-groove on the bearing seat through various fixed ends, and ensure that the nesting area on the middle flat foil corresponds to the protrusion on the lower surface of the rectangular bottom foil.

2. The bearing according to claim 1, characterized in that Multiple layers of intermediate flat foils may be provided on the radial air bearing.

3. The bearing according to claim 2, characterized in that Multiple layers of intermediate flat foils are stacked and assembled, and the installation clearance of the radial air bearing can be adjusted by changing the number of intermediate flat foils.

4. The bearing according to claim 3, characterized in that The top flat foil has a spread angle of 80 degrees and a thickness of 0.1 mm.

5. The bearing according to claim 4, characterized in that The depth of the etched groove is 0.015 mm.

6. The bearing according to claim 5, characterized in that The thickness of the preload gasket ranges from 0.05mm to 0.15mm.

7. The bearing according to claim 6, characterized in that The narrow sheet has a width of 2 mm and a thickness of 0.02 mm. The corrugated foil has an angle of 58° and a thickness of 0.1 mm. The thickness of the middle bottom foil is 0.08 mm. The number and distribution of triangles or trapezoids are consistent with the double arches on the corrugated foil.

8. The bearing according to claim 7, characterized in that The thickness of the protrusions on the rectangular bottom foil is 0.02 mm.

9. The bearing according to claim 8, characterized in that The protrusion is in the shape of a long strip and runs through the entire rectangular bottom foil in the thickness direction.

10. The bearing according to claim 9, characterized in that The materials of top flat foil, corrugated foil, middle bottom foil, middle flat foil and rectangular bottom foil are all GH4169, and the bearing seat material is 7A02.

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