Thrust foil air bearing with double waves and double tops

Abstract

The invention belongs to the field of foil aerodynamic bearings, and relates to a thrust foil air bearing with double waves and double tops. Comprising a thick top foil, a thin top foil, a middle plate, a bump foil and a bearing seat, the bearing seat and the middle plate are the same in appearance, the middle plate is of a disc structure, the disc structure is evenly divided into a plurality of fan-shaped tiles, thin top foils are welded to one sides of the upper ends of the fan-shaped tiles, thick top foils are welded to the other sides of the upper ends of the fan-shaped tiles, and bump foils are welded to one sides of the lower ends of the fan-shaped tiles. The welding spot position of the bump foil on the fan-shaped tile is coincident with the welding spot position of the thin top foil on the fan-shaped tile, a plurality of pawls are arranged on the lower surface of the middle plate and matched with a plurality of grooves correspondingly formed in the bearing seat, and the middle plate is installed on the bearing seat through the pawls; the bump foil is specifically an integral large arc, and the large arc is composed of a plurality of double-arch structures. The double-arch bump foil has the characteristics of small rigidity under small bearing capacity and large rigidity under large bearing capacity, and the adaptability is higher.

Description

Technical Field

[0001] The invention belongs to the field of foil gas dynamic pressure bearings and relates to a thrust foil air bearing with double waves and double tops. Background Art

[0002] Bearings are used to support the rotor system and are key components of rotating machinery. Their performance has a direct impact on the operating quality of rotating machinery. The foil dynamic pressure gas bearing uses ambient gas as the lubricating medium to form a dynamic pressure gas film between the rotor and the top flat foil, thereby generating bearing capacity. It has the advantages of oil-free, micro-vibration, low friction, high speed, good environmental adaptability and long life. It also has good impact resistance and strong adaptability, which can ensure the stability of the rotor at high speed. It has been widely used in high-speed rotating machinery such as turbine expanders, centrifugal fans and centrifugal compressors.

[0003] The hydrodynamic gas bearing is a passive sliding bearing. The foil gas bearing is an elastic support structure added to the rigid hydrodynamic bearing. It is usually composed of a top flat foil that forms a lubricating air film and a bottom elastic wave foil with certain stiffness and damping characteristics. On the one hand, the thickness of the corrugated foil and the top foil of the air foil bearing is extremely small. The top foil is supported by the corrugated foil, and the height of each corrugated arch on the corrugated foil is consistent. The top of the corrugated arch is in contact with the flat foil, resulting in more contact stress concentration points in the foil bearing, which affects the formation of the air film. On the other hand, the structural stiffness brought by a single corrugated foil is usually only applicable to a certain optimal load-bearing capacity range, and the axial load-bearing capacity varies greatly, and the thrust bearing has poor adaptability. In addition, a small amount of deflection will inevitably occur when the bearing and the thrust plate are installed, and a large amount of frictional heat will be generated when the thrust bearing is working. The current bearing structure does not take this phenomenon into consideration.

[0004] Therefore, how to reduce the stress concentration points of air foil bearings, accelerate the formation of air film and maintain the stability of air film, and provide multi-level structural stiffness under different load capacities are key issues that need to be addressed in the industry. Figure 1 As shown, it has the following shortcomings:

[0005] 1. The wedge-shaped structure of the air film depends on the wave height, which is difficult to achieve. The cost of processing and manufacturing the mold is high, and the stamping rebound makes it difficult to ensure the accuracy, which requires repeated debugging;

[0006] 2. The wedge shape of the wave foil after deformation will also be affected, gradually deviating from the optimal design value of the bearing;

[0007] 3. The thrust bearing has poor adaptability to strong and weak axial forces. The foil of the large-load thrust bearing is often designed to be harder, while the foil of the light-load thrust air bearing is softer and lacks automatic adjustment ability.

[0008] 4. During the startup process, the fan-shaped top foil of the thrust foil bearing and the thrust plate are in full surface contact, resulting in a large friction torque, which is not conducive to reducing the floating pressure or floating speed;

[0009] 5. The outer ring of the thrust bearing base plate is processed with a U-shaped notch and fixed with pins. This method will increase the outer diameter of the bearing and the end cover, which is not conducive to the lightweight of products such as turbines and air compressors;

[0010] 6. The impact resistance of a single corrugated foil is poor. Under the action of a large instantaneous axial load, the corrugated foil is easily crushed and deformed, and cannot recover its elasticity, causing bearing failure and rotor jamming.

[0011] 7. Inadequate measures were not taken to solve the installation deviation problem between the thrust plate and the thrust air bearing; 8. Inadequate measures were not taken to achieve bleed air cooling inside the thrust foil air bearing. Summary of the invention

[0012] Purpose of the Invention

[0013] A thrust foil air bearing structure with double waves and double tops is provided. The invention has the characteristics of simple structure, convenient manufacturing, strong adaptability, high impact resistance level, and saving installation space.

[0014] Technical Solution

[0015] A thrust foil air bearing with double waves and double tops, see Figure 2 to Figure 6 , including a thick top foil 1, a thin top foil 2, an intermediate plate 3, a corrugated foil 4, and a bearing seat 5; the bearing seat 5 has the same appearance as the intermediate plate 3, the intermediate plate 3 is a disc structure, the disc structure is divided into a plurality of fan-shaped tiles, the thin top foil 2 is welded on one side of the upper end of the fan-shaped tile, the thick top foil 1 is welded on the other side of the upper end of the fan-shaped tile, the corrugated foil 4 is welded on one side of the lower end of the fan-shaped tile, the welding point position of the corrugated foil 4 on the fan-shaped tile should coincide with the welding point position of the thin top foil 2 on the fan-shaped tile, a plurality of pawls are provided on the lower surface of the intermediate plate 3, which match the plurality of grooves correspondingly arranged on the bearing seat 5, and the intermediate plate 3 is installed on the bearing seat 5 through the pawls; the corrugated foil 4 is specifically an integral large arc, and the large arc is composed of a plurality of double-arch structures.

[0016] Furthermore, the number of the corrugated foils 4 provided at the lower end of the fan-shaped tile should be consistent with the number of the thick top foils 1 and the thin top foils 2 , and there should be a gap between any two corrugated foils 4 .

[0017] Furthermore, the bearing seat 5 is provided with ventilation grooves, and cooling air flows along the grooves from the outer side to the inner side of the thrust plate, and there is an acute angle between the flow direction and the rotation direction.

[0018] Furthermore, a sawtooth groove 21 is provided on the free end of the thin top foil 2, which can increase the heat dissipation of the top foil.

[0019] Furthermore, a ventilation slot 11 is provided on the fixed end of the thick top foil 1, which is conducive to the wind entering the thrust air bearing from the upper side of the top foil.

[0020] Furthermore, the number of the fan-shaped tiles is 6-12, and generally the number is an even number.

[0021] Furthermore, the corrugated foil 4 is provided with cutting grooves, which, on the one hand, enable each corrugated foil to adaptively slide and deform, and on the other hand, can improve the heat dissipation inside the bearing.

[0022] Furthermore, the thrust plate 7 rotates at a high speed and cooperates with the thrust foil air bearing to form an air film to provide an axial force.

[0023] Furthermore, the materials of the thick top foil, the thin top foil, the middle plate and the corrugated foil are all GH4169, and the thicknesses are 0.12 mm, 0.02 mm, 0.3 mm and 0.1 mm respectively.

[0024] The beneficial effects of this application are:

[0025] The double-arch wave foil has the characteristics of small stiffness under small load and large stiffness under large load. It has stronger adaptability and can effectively expand the application range of a single model of bearings. The wave foil has a large arc, which is used for pre-tightening during installation, which can effectively solve the problem of rotor installation deviation of turbines, air compressors, etc. The top foil has a small arc, which can reduce the contact area and friction torque with the thrust plate when the product starts, effectively reducing the floating pressure or floating speed. The thin top foil pad forms a wedge-shaped air film at the bottom of the thick top foil, and the wedge-shaped profile can be adjusted by the thickness of the thin top foil. Compared with the wedge-shaped method that relies on differential wave arch construction, it is simpler and more reliable. The double-layer top foil and the double-arch wave foil are welded on both sides of the middle plate respectively, with a simpler structure, convenient manufacturing and easy precision assurance. The four ratchets of the middle plate cooperate with the U-shaped groove of the bearing seat to realize the installation and positioning of the bearing. Compared with the pin fixing method, it occupies less space and is conducive to reducing the size and weight of the whole machine. The middle plate has multiple uses such as ratchet positioning, tongue pre-tightening, and cooling air flow. The thick top foil is provided with U-shaped grooves, the thin top foil is processed with small serrations, and the corrugated foil is arranged with separation grooves. Multiple measures are taken to ensure sufficient flow of cooling air inside the bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a traditional thrust foil air bearing structure;

[0027] Figure 2 The overall assembly structure of the thrust air bearing of the present invention;

[0028] Figure 3A Double-layer top foil structure;

[0029] Figure 3B Double-layer top foil welding installation structure;

[0030] Figure 4A Schematic diagram of the structure of thick top foil;

[0031] Figure 4B Schematic diagram of the structure of the thin top foil;

[0032] Figure 5 This is a schematic diagram of the double-arch corrugated foil structure and welding installation;

[0033] Figure 6 It is a schematic diagram of the deformation of the corrugated foil under the action of bearing force;

[0034] Figure 7 is a schematic diagram of the structure of the middle plate;

[0035] Figure 8 This is a schematic diagram of the bearing seat structure.

[0036] Fig. 9 Schematic diagram of the working of thrust foil air bearing;

[0037] Figure numerals: 1 - thick top foil, 2 - thin top foil, 3 - middle plate, 4 - corrugated foil, 5 - bearing seat, 6 - welding point, 7 - thrust plate. DETAILED DESCRIPTION

[0038] 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.

[0039] 1. A thrust foil air bearing with double waves and double tops, wherein the double top foil and the double arched wave foil are welded on both sides of the middle plate respectively. The welding direction of the thick top foil is the rotation direction of the thrust plate during operation, and the welding directions of the thin top foil and the wave foil are opposite to the thick top foil.

[0040] 2. The aforementioned thin top foil generally has a thickness of 0.01 to 0.05 mm and a smaller extension angle than the thick top foil, and is used to prop up the thick top foil to construct a wedge-shaped air film.

[0041] 3. The aforementioned thin top foil has a sawtooth groove processed on the free end edge, so that the cooling airflow can more easily enter the bottom of the thick top foil, which is used to improve the cooling of both sides of the thick top foil.

[0042] 4. The thickness of the aforementioned thick top foil is generally between 0.1 and 0.2 mm, and a wear-resistant and friction-reducing coating is sprayed on the surface to form a dynamic pressure air film with the thrust plate.

[0043] 5. The aforementioned thick top foil has an arc along the circumferential direction, so that the contact area and friction torque with the thrust plate are reduced during the starting process.

[0044] 6. The aforementioned thick top foil is processed with a U-shaped groove 11 near the welding area, which is used to further introduce the cooling airflow between the thrust plate and the thick top foil into the interior of the bearing to cool other foils.

[0045] 7. The thickness of the aforementioned corrugated foil is generally between 0.08 and 0.15 mm, and it has an integral large arc, which plays a role of elastic support and pre-tightening.

[0046] 8. On the aforementioned wave foil, two adjacent wave arches are equivalent to one large wave arch under light load, and will deform under high load. The bottom angle of the wave arch contacts the bearing seat and plays a supporting role together, that is, one large wave arch is transformed into two small wave arches, which improves the structural stiffness of the wave foil.

[0047] 9. The aforementioned corrugated foil is processed with a plurality of dividing grooves 41, which, on the one hand, enables each corrugated arch to slide and deform better, and on the other hand, enables the cooling airflow to flow more fully in the corrugated foil.

[0048] 10. The aforementioned bottom plate partially tilts up four ratchet claws 31, which cooperate with four U-shaped grooves on the bearing seat for installing the thrust bearing.

[0049] 11. The aforementioned bottom plate is partially processed with a raised small tongue 32, which is used for installation pre-tightening on the one hand, and for realizing the relative flow of cooling airflow on both sides of the bearing on the other hand.

[0050] 12. The aforementioned bearing seat has four U-shaped grooves 51, which cooperate with the pawls 31 of the bottom plate. Several cooling channels 52 are evenly processed along the circumferential direction. The cooling channels 52 form an angle with the direction of the corrugated foil, which will not interfere with the sliding deformation of the corrugated foil. It is used for air cooling on the back of the air bearing. The airflow of each air channel is directed radially from the outside of the bearing to the inside.

[0051] The middle plate is partially bent along the circumferential direction to form four ratchet claws. The bearing seat is arranged with four evenly distributed U-shaped grooves. The ratchet claws cooperate with the U-shaped grooves to be used for installation and fixation of the thrust air bearing.

[0052] The middle plate is evenly arranged with tongue pieces along the circumferential direction, which are used for pre-tightening the bearing during installation. The formed notches are conducive to the through-flow of cooling airflow on both sides of the bearing.

[0053] The bearing seat is processed with cooling channels evenly distributed along the circumferential direction for sufficient air cooling of the bearing, and the direction of the channel is consistent with the sliding direction of the corrugated foil.

[0054] The double-layer top foil is reversely welded and laid on one side of the middle plate, the thin top foil is padded on the bottom of the thick top foil to form a wedge shape, and the thick top foil contacts the thrust plate to form a dynamic pressure air film.

[0055] The upper surface of the thick top foil is coated with a polytetrafluoroethylene wear-resistant and friction-reducing coating, and a large arc is pre-processed so that the contact between the thick top foil and the thrust plate is line contact rather than surface contact.

[0056] The corrugated foil is welded to the other side of the middle plate. The corrugated foil has an integral large arc for installation pre-tightening, which can alleviate the installation deflection of the thrust bearing sleeve or the rotor.

[0057] The wave foil has two interconnected small wave arches, which will deform into one large wave arch under pressure, making the thrust bearing adaptive.

[0058] The corrugated foil is processed with two dividing grooves along the circumferential direction, which makes the sliding deformation of each corrugated arch more flexible and makes the cooling air flow inside the bearing flow more smoothly.

[0059] The welding side of the thick top foil is machined with a U-shaped groove, and the non-welding end of the thin top foil is machined with a serrated groove to improve the heat dissipation of the flat foil.

[0060] The materials of thick top foil, thin top foil, middle plate and corrugated foil are all GH4169, with thicknesses of 0.12mm, 0.02mm, 0.3mm and 0.1mm respectively.

[0061] The top foil and the wave foil are welded to both sides of the middle plate by resistance welding, and each piece has at least 5 welding points. The rotation direction of the thick top foil is opposite to that of the thin top foil, and the welding direction of the thick top foil is opposite to that of the wave foil.

[0062] Example 2

[0063] In some embodiments, a thrust foil air bearing with double waves and double tops has the following features compared to Example 1:

[0064] The middle plate is partially bent along the circumferential direction to form six or eight ratchet claws, and the bearing seat is arranged with the same number of evenly distributed U-shaped grooves, and the two are used in conjunction with each other to install and fix the thrust air bearing.

[0065] The bearing seat is processed with uniformly distributed cooling channels along the circumferential direction for air bleed cooling of the bearing, and the angle between the direction of the channel and the sliding direction of the corrugated foil is an acute angle not greater than 30°.

[0066] The surface of the thick top foil is coated with molybdenum disulfide or other composite wear-resistant and friction-reducing coatings.

[0067] 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 2. Under the action of pressure, the connected arches will deform into a large wave arch, so that the thrust bearing has adaptability.

[0068] The corrugated foil is processed with no less than 3 dividing grooves along the circumferential direction, so that the sliding deformation of each corrugated arch is more flexible and the cooling air flow inside the bearing flows more smoothly.

[0069] The materials of thick top foil, thin top foil, middle plate and corrugated foil are all GH4145 or Inconcel X-750 or InconcelX-718.

[0070] The top foil and the corrugated foil are respectively welded to the two sides of the middle plate by laser welding.

[0071] 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 thrust foil air bearing with double waves and double tops, characterized in that: It includes a thick top foil, a thin top foil, an intermediate plate, a corrugated foil and a bearing seat; the bearing seat and the intermediate plate have the same appearance, the intermediate plate is a disc structure, the disc structure is divided into a plurality of fan-shaped tiles, the thin top foil is welded on one side of the upper end of the fan-shaped tile, the thick top foil is welded on the other side of the upper end of the fan-shaped tile, the corrugated foil is welded on one side of the lower end of the fan-shaped tile, the welding point position of the corrugated foil on the fan-shaped tile should coincide with the welding point position of the thin top foil on the fan-shaped tile, a plurality of pawls are provided on the lower surface of the intermediate plate, which match a plurality of grooves correspondingly arranged on the bearing seat, and the intermediate plate is installed on the bearing seat through the pawls; the corrugated foil is specifically an integral large arc, and the large arc is composed of a plurality of double-arch structures.

2. The bearing according to claim 1, characterized in that The number of the corrugated foils arranged at the lower end of the fan-shaped tile should be consistent with the number of the thick top foil and the thin top foil, and there is a gap between the two corrugated foils.

3. The bearing according to claim 2, characterized in that The bearing seat is provided with ventilation grooves, and cooling air flows from the outer side to the inner side of the thrust plate along the ventilation grooves, and an acute angle is formed between the flow direction and the rotation direction.

4. The bearing according to claim 3, characterized in that A sawtooth groove is arranged on the free end of the thin top foil, so as to increase the heat dissipation of the top foil.

5. The bearing according to claim 4, characterized in that A ventilation slot is arranged on the fixed end of the thick top foil, which is conducive to the wind entering the thrust air bearing from the upper side of the top foil.

6. The bearing according to claim 5, characterized in that The number of the fan-shaped tiles is 6-12, and the number is an even number.

7. The bearing according to claim 6, characterized in that The corrugated foil is provided with cutting grooves, which, on the one hand, enable each corrugated foil to adaptively slide and deform, and on the other hand, can improve the heat dissipation inside the bearing.

8. The bearing according to claim 7, characterized in that The thrust plate rotates at high speed and cooperates with the thrust foil air bearing to form an air film to provide axial force.

9. The bearing according to claim 8, characterized in that The materials of thick top foil, thin top foil, middle plate and corrugated foil are all GH4169, with thicknesses of 0.12mm, 0.02mm, 0.3mm and 0.1mm respectively.

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