Dynamic pressure gas thrust bearing, rotor assembly and compressor

Abstract

The application provides a dynamic pressure gas thrust bearing, a rotor assembly and a compressor. The dynamic pressure gas thrust bearing comprises a bearing shell (25), a top foil (21) fixed at one end on the bearing shell (25) and movable at the other end relative to the bearing shell (25), a wave foil mounting space formed between the top foil (21) and the bearing shell (25), a first wave foil (22), a second wave foil (23) and a third wave foil (24), the first wave foil (22), the second wave foil (23) and the third wave foil (24) are sequentially and spacedly arranged in the wave foil mounting space along the airflow direction, and the rigidity of the first wave foil (22) and the third wave foil (24) is greater than that of the second wave foil (23). According to the dynamic pressure gas thrust bearing, a secondary wedge structure can be formed on the surface of the top foil at high speed, and the carrying capacity and adaptive capacity of the bearing in a high-speed environment can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bearings, in particular to a dynamic pressure gas thrust bearing, a rotor assembly and a compressor. BACKGROUND

[0002] A centrifugal compressor is a kind of high-speed rotating machinery, and bearings commonly used include rolling bearings, sliding bearings, magnetic suspension bearings and the like. However, with the development of the industry of miniaturization, high-speed and oil-free of the centrifugal compressor, higher requirements are put forward for the high-temperature resistance of the bearing under high-speed state, and the gas suspension bearing emerges as the times require.

[0003] According to the different lubricating gas film generation mechanisms, the gas bearing is divided into a static pressure gas bearing and a dynamic pressure gas bearing. In the dynamic pressure gas bearing, the wave foil type dynamic pressure gas bearing has the most research results in the existing literature.

[0004] The wave foil type dynamic pressure gas thrust bearing is a kind of wave foil type dynamic pressure gas bearing, and provides axial stiffness and damping for a rotor system. The typical structure mainly includes a bearing shell, a wave foil and a top foil, and the working environment is generally air or refrigerant. Similar to the pad of the oil lubricated thrust bearing, the top foil of the wave foil type dynamic pressure gas thrust bearing is generally designed in a fan shape, and acts as a pad. In order to be uniformly stressed, the top foils are uniformly distributed in the circumferential direction. The wave foils under the top foils have a special corrugated structure, and act as elastic supports, and are the main source of the stiffness and damping of the thrust bearing. One end of the wave foil and the top foil is fixed on a bearing seat, and the other end is free. There is a convergent included angle between the front end of the top foil and the thrust disc of the rotor, forming a wedge-shaped area, and the size of the convergent included angle is generally called the wedge degree. The rear end of the top foil is parallel to the thrust disc, forming a load bearing area. When the rotor rotates at high speed, the gas is quickly converged and the pressure is increased in the wedge-shaped area under the action of the convergent included angle through the dynamic pressure effect, so that a high-pressure gas film is formed in the load bearing area to support the rotor.

[0005] As can be seen from the above description, the key to the work of the dynamic pressure gas thrust bearing is to form a high-pressure gas film. The dynamic pressure gas thrust bearing of the existing structure realizes the dynamic pressure effect through the convergent included angle structure. For the existing bearing structure, once the bearing is assembled, the convergent included angle size is fixed, and it is the only structure that can quickly increase the gas pressure. However, the actual working speed of the machine is not constant, especially for machines using variable frequency motors, which need to run at variable speed frequently. The required load stiffness of the rotor system changes with the speed, and the existing bearing structure is difficult to adapt to the high-speed environment and provide higher load capacity due to the fixed size of the convergent included angle. SUMMARY

[0006] The main purpose of the present application is to provide a dynamic pressure gas thrust bearing, a rotor assembly and a compressor, which can form a secondary wedge structure on the top foil surface at high speed, and can improve the bearing capacity and adaptive capacity of the bearing in a high-speed environment.

[0007] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a dynamic pressure gas thrust bearing is provided, comprising:

[0008] A bearing housing;

[0009] A top foil, one end of which is fixed on the bearing housing, and the other end of which is movable relative to the bearing housing, and a wave foil mounting space is formed between the top foil and the bearing housing;

[0010] A first wave foil;

[0011] A second wave foil;

[0012] A third wave foil, the first wave foil, the second wave foil and the third wave foil are sequentially and spacedly arranged in the wave foil mounting space along the airflow direction, and the stiffness of the first wave foil and the third wave foil is greater than the stiffness of the second wave foil.

[0013] Further, the stiffness of the first wave foil is less than the stiffness of the third wave foil.

[0014] Further, the first wave foil, the second wave foil and the third wave foil each comprise a fixed end and a free end, the fixed end is fixedly arranged on the bearing housing, and the free end is movable relative to the bearing housing, and the free end of the same wave foil is located on the downstream side of the fixed end in the airflow direction.

[0015] Further, the top foil comprises a wedge-shaped area and a flat area, part of the first wave foil is located in the wedge-shaped area, and part of the first wave foil is located in the flat area, and the second wave foil and the third wave foil are located in the flat area.

[0016] Further, the flat area comprises a medium stiffness bearing area, the first wave foil comprises a first straight edge area, a variable height area and a medium stiffness wave foil bearing area which are sequentially arranged along the airflow direction, the first straight edge area is fixedly connected with the bearing housing, the variable height area is arranged corresponding to the wedge-shaped area, and the medium stiffness wave foil bearing area is arranged corresponding to the medium stiffness bearing area of the flat area.

[0017] Further, the flat area further comprises a low stiffness suspended bearing area and a low stiffness bearing area, the second wave foil comprises a second straight edge area, a low stiffness wave foil suspended area and a low stiffness wave foil bearing area which are sequentially arranged along the airflow direction, the second straight edge area is fixedly connected with the bearing housing, a top portion of the low stiffness wave foil suspended area and the top foil form a preset interval, the low stiffness wave foil suspended area is arranged corresponding to the low stiffness suspended bearing area of the flat area, and the low stiffness wave foil bearing area is arranged corresponding to the low stiffness bearing area of the flat area.

[0018] Further, the number of arch-shaped protrusions of the second wave foil is two.

[0019] Further, the planar area further comprises a high-rigidity bearing area, the third wave foil comprises a third straight edge area and a high-rigidity wave foil bearing area, the third straight edge area is fixedly connected with the bearing shell, and the high-rigidity wave foil bearing area is arranged corresponding to the high-rigidity bearing area.

[0020] Further, the materials of the first wave foil, the second wave foil and the third wave foil are the same, the thickness of the first wave foil is T1, the thickness of the second wave foil is T2, and the thickness of the third wave foil is T3, T2 < T1 < T3.

[0021] Further, the materials of the first wave foil, the second wave foil and the third wave foil are different, and the thicknesses are the same, the material rigidity of the second wave foil is smaller than that of the first wave foil, and the material rigidity of the first wave foil is smaller than that of the third wave foil.

[0022] Further, the free end of the third wave foil is located inside the movable end of the top foil, and has a preset distance from the movable end.

[0023] Further, the area of the first wave foil is larger than that of the third wave foil, and the area of the third wave foil is larger than that of the second wave foil.

[0024] Further, the bearing shell is a ring-shaped flat plate, the top foil is a plurality of and arranged along the circumference of the bearing shell in sequence, and the first wave foil, the second wave foil and the third wave foil are arranged corresponding to the top foil.

[0025] Further, the number of the top foil is even.

[0026] According to another aspect of the present application, a rotor assembly is provided, comprising a rotating shaft, a thrust disc and a dynamic pressure gas thrust bearing, the dynamic pressure gas thrust bearing is fixedly arranged on the rotating shaft and corresponding to the thrust disc, and the top surface of the top foil faces the thrust disc.

[0027] According to another aspect of the present application, a compressor is provided, comprising the dynamic pressure gas thrust bearing or the rotor assembly.

[0028] The technical scheme of the application is applied to the dynamic pressure gas thrust bearing, which comprises a bearing shell, a top foil fixed at one end of the bearing shell and movable relative to the bearing shell at the other end, a first wave foil, a second wave foil and a third wave foil, the first wave foil, the second wave foil and the third wave foil are sequentially and spacedly arranged in the wave foil mounting space along the airflow direction, and the rigidity of the first wave foil and the third wave foil is greater than that of the second wave foil. The dynamic pressure gas thrust bearing is reformed in the wave foil structure, the wave foil structure is divided into three parts, the rigidity of the second wave foil in the middle region is the smallest, the characteristics that the gas film pressure changes with the rotating speed can be utilized, a primary wedge structure is formed on the surface of the top foil at the air inlet position when the rotor is at a low rotating speed, at this time, the gas pressure on the second wave foil is small, and no obvious concave phenomenon is formed, when the rotor rotates at a high speed, the gas pressure is large, the gas pressure on the top foil is also large, and because the rigidity of the second wave foil is smaller than that of the first wave foil and the third wave foil, the top foil in the corresponding region of the second wave foil is deeply concave under the action of the gas pressure, a secondary wedge structure is formed in the region of the second wave foil, so that the gas film has a second dynamic pressure effect, the gas film pressure can be effectively improved, and higher bearing capacity is provided for the rotor, because the concave depth of the second wave foil can change with the rotating speed, the wedge angle formed can also change with the rotating speed, so that suitable gas film pressure can be provided for the rotor at different rotating speeds, the vibration caused by the dynamic pressure gas film fluctuation when the rotating speed changes is reduced, and the bearing capacity and adaptive capacity of the bearing in the high-speed environment are improved. BRIEF DESCRIPTION OF DRAWINGS

[0029] The drawings constituting a part of the specification of the application are used to provide further understanding of the application, the illustrative embodiments of the application and the description thereof are used to explain the application, and do not constitute improper limitation on the application. In the drawings:

[0030] Figure 1 A perspective sectional structure schematic view of a rotor assembly of an embodiment of the application is shown;

[0031] Figure 2 A structure schematic view of a rotor assembly of an embodiment of the application is shown;

[0032] Figure 3 A sectional structure schematic view of A-A of Figure 1 is shown;

[0033] Figure 4 An enlarged structure schematic view of A of Figure 3 is shown;

[0034] Figure 5 An enlarged structure schematic view of B of Figure 4 is shown;

[0035] Figure 6 It shows Figure 4 A magnified structural diagram at point C;

[0036] Figure 7 It shows Figure 4 A magnified structural diagram at point D;

[0037] Figure 8 A schematic diagram of the top foil of the hydrodynamic gas thrust bearing according to an embodiment of the present invention is shown;

[0038] Figure 9 A three-dimensional structural schematic diagram of the top foil of the hydrodynamic gas thrust bearing according to an embodiment of the present invention is shown;

[0039] Figure 10 A schematic diagram of the corrugated foil of the hydrodynamic gas thrust bearing according to an embodiment of the present invention is shown; and

[0040] Figure 11 A three-dimensional structural schematic diagram of the corrugated foil of the dynamic pressure gas thrust bearing according to an embodiment of the present invention is shown.

[0041] The above figures include the following reference numerals:

[0042] 11. Shaft; 12. Thrust disc; 2. Hydrodynamic gas thrust bearing; 21. Top foil; 211. Wedge-shaped area; 212. Medium stiffness load-bearing area; 213. Low stiffness suspended load-bearing area; 214. Low stiffness load-bearing area; 215. High stiffness load-bearing area; 22. First corrugated foil; 221. First straight edge area; 222. Variable height area; 223. Medium stiffness corrugated foil load-bearing area; 23. Second corrugated foil; 231. Second straight edge area; 232. Low stiffness corrugated foil suspended area; 233. Low stiffness corrugated foil load-bearing area; 24. Third corrugated foil; 241. Third straight edge area; 242. High stiffness corrugated foil load-bearing area; 25. Bearing housing. Detailed Implementation

[0043] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0044] See also Figures 1 to 11 As shown, according to an embodiment of the present invention, the hydrodynamic gas thrust bearing includes: a bearing housing 25; a top foil 21, one end of which is fixed to the bearing housing 25 and the other end of which is movable relative to the bearing housing 25, forming a corrugated foil mounting space between the top foil 21 and the bearing housing 25; a first corrugated foil 22; a second corrugated foil 23; and a third corrugated foil 24. The first corrugated foil 22, the second corrugated foil 23, and the third corrugated foil 24 are arranged sequentially at intervals in the corrugated foil mounting space along the airflow direction, and the stiffness of the first corrugated foil 22 and the third corrugated foil 24 is greater than the stiffness of the second corrugated foil 23.

[0045] The dynamic pressure gas thrust bearing reforms the wave foil structure, divides the wave foil structure into three parts, and makes the rigidity of the second wave foil 23 in the middle region minimum. The characteristics of the gas film pressure changing with the rotating speed can be used to form a primary wedge structure on the surface of the top foil 21 at the inlet position when the rotor is at a low rotating speed. At this time, the second wave foil 23 is subjected to a smaller gas pressure, and no obvious concave phenomenon is formed. When the rotor rotates at a high speed, the gas pressure is larger, and the top foil 21 is subjected to a larger gas pressure. Since the rigidity of the second wave foil 23 is smaller than that of the first wave foil 22 and the third wave foil 24, the top foil 21 in the corresponding region of the second wave foil 23 is subjected to a larger concave depth under the action of the gas pressure, and a secondary wedge structure can be formed in the region of the second wave foil 23, so that the gas film can perform a second dynamic pressure effect, and the gas film pressure can be effectively improved to provide higher carrying capacity for the rotor. Since the concave depth of the second wave foil 23 can change with the rotating speed, the wedge angle formed can also change with the rotating speed, so that suitable gas film pressure can be provided for rotors at different rotating speeds, the vibration of the rotor caused by the fluctuation of the dynamic pressure gas film when the rotating speed changes is reduced, and the carrying capacity and adaptive ability of the bearing in a high-speed environment are improved.

[0046] In one embodiment, the rigidity of the first wave foil 22 is smaller than the rigidity of the third wave foil 24. In this embodiment, the rigidity of the second wave foil 23 located in the middle position is the smallest, the rigidity of the first wave foil 22 located on the gas inlet side is the second smallest, and the rigidity of the third wave foil 24 located on the gas outlet side is the largest. This structure can form a primary wedge structure by using the first wave foil 22. When the gas flow reaches the second wave foil 23, a concave region is formed due to the low rigidity of the second wave foil 23, and the gas flow is collected in the concave region and then forms a gas film again by using the dynamic pressure effect along the secondary wedge structure formed by the concave of the second wave foil 23. Under the same gas pressure, the gas film thickness formed by the top foil 21 corresponding to the first wave foil 22 is smaller than the gas film thickness formed by the top foil 21 corresponding to the second wave foil 23, and larger than the gas film thickness formed by the top foil corresponding to the third wave foil 24. Therefore, during the gas flow, the gas film thickness generally presents a form of becoming larger from smaller and then becoming smaller again. This form is more conducive to forming a secondary wedge structure on the surface of the top foil when the rotor rotates at a high speed, so that the gas film is more likely to perform a second dynamic pressure effect, and the gas film pressure formed is larger, which is more conducive to improving the gas film pressure and can more effectively improve the carrying capacity of the dynamic pressure gas thrust bearing.

[0047] In one embodiment, the first wave foil 22, the second wave foil 23 and the third wave foil 24 each include a fixed end and a free end. The fixed end is fixedly arranged on the bearing housing 25, and the free end is movable relative to the bearing housing 25. The free end of the same wave foil is located on the downstream side of the fixed end in the gas flow direction.

[0048] In the embodiment, the first wave foil 22 comprises a free end and a fixed end, the second wave foil 23 comprises a free end and a fixed end, and the third wave foil 24 comprises a free end and a fixed end, wherein the fixed end of the second wave foil 23 is adjacent to the free end of the first wave foil 22, the fixed end of the third wave foil 24 is adjacent to the free end of the second wave foil 23, and the fixed end of the first wave foil 22 is located at the gas flow inlet, and the free end of the third wave foil 24 is located at the gas flow outlet, so that the flow of the gas flow matches the structural arrangement of each wave foil, each wave foil can play a good dynamic pressure support effect, and it is more conducive to forming the gas film.

[0049] The fixed end of each wave foil is fixedly connected to the bearing shell 25, and the free end can be stretched relative to the bearing shell 25, so that each wave foil can form adaptive support for the top foil 21 under the action of the dynamic pressure of the gas, and the gas film thickness at the top of the top foil 21 is adjusted according to the dynamic pressure of the gas.

[0050] In one embodiment, the top foil 21 comprises a wedge-shaped area 211 and a flat area, part of the first wave foil 22 is located in the wedge-shaped area 211, and part is located in the flat area, and the second wave foil 23 and the third wave foil 24 are located in the flat area. In the embodiment, the wedge-shaped area 211 of the top foil 21 is used to cooperate with the thrust disc 12 to form a convergence angle θ1, and when the rotor rotates at a high speed under the action of the electromagnetic field of the motor stator, the gas film can be formed by the dynamic pressure under the action of the convergence angle θ1 when the rotor reaches the designed rotating speed, so as to support the rotation of the rotor.

[0051] In one embodiment, the flat area comprises a medium-rigidity bearing area 212, the first wave foil 22 comprises a first straight edge area 221, a variable height area 222 and a medium-rigidity wave foil bearing area 223 arranged in sequence along the flow direction of the gas flow, the first straight edge area 221 is fixedly connected to the bearing shell 25, the variable height area 222 is arranged corresponding to the wedge-shaped area 211, and the medium-rigidity wave foil bearing area 223 is arranged corresponding to the medium-rigidity bearing area 212 of the flat area.

[0052] In one embodiment, the flat area further comprises a low-rigidity suspended bearing area 213 and a low-rigidity bearing area 214, the second wave foil 23 comprises a second straight edge area 231, a low-rigidity wave foil suspended area 232 and a low-rigidity wave foil bearing area 233 arranged in sequence along the flow direction of the gas flow, the second straight edge area 231 is fixedly connected to the bearing shell 25, a preset interval is formed between the top of the low-rigidity wave foil suspended area 232 and the top foil 21, the low-rigidity wave foil suspended area 232 is arranged corresponding to the low-rigidity suspended bearing area 213 of the flat area, and the low-rigidity wave foil bearing area 233 is arranged corresponding to the low-rigidity bearing area 214 of the flat area.

[0053] In one embodiment, the planar area further comprises a high-rigidity bearing area 215, the third wave foil 24 comprises a third straight edge area 241 and a high-rigidity wave foil bearing area 242, the third straight edge area 241 is fixedly connected with the bearing shell 25, and the high-rigidity wave foil bearing area 242 is arranged corresponding to the high-rigidity bearing area 215.

[0054] In one embodiment, the bearing shell 25 is a ring-shaped flat plate, the top foil 21 is a plurality of and arranged along the circumference of the bearing shell 25 in sequence, and the first wave foil 22, the second wave foil 23 and the third wave foil 24 are arranged corresponding to the top foil 21.

[0055] In one embodiment, the materials of the first wave foil 22, the second wave foil 23 and the third wave foil 24 are the same, the thickness of the first wave foil 22 is T1, the thickness of the second wave foil 23 is T2, and the thickness of the third wave foil 24 is T3, T2 < T1 < T3.

[0056] In one embodiment, the materials of the first wave foil 22, the second wave foil 23 and the third wave foil 24 are different, and the thicknesses are the same, the material rigidity of the second wave foil 23 is less than that of the first wave foil 22, and the material rigidity of the first wave foil 22 is less than that of the third wave foil 24.

[0057] For reference Figures 8 to 11 As shown, according to different bearing areas, the single top foil 21 of the embodiment of the present application is subdivided into a wedge-shaped area, a medium-rigidity bearing area 212, a low-rigidity suspended bearing area 213, a low-rigidity bearing area 214 and a high-rigidity bearing area 215. Similarly, according to different bearing areas, the wave foil structure of the embodiment of the present application is divided into three types of the first wave foil 22 of medium rigidity, the second wave foil 23 of low rigidity and the third wave foil 24 of high rigidity, wherein the first wave foil 22 is divided into a first straight edge area 221, a variable height area 222 and a medium-rigidity wave foil bearing area 223.

[0058] The wedge-shaped area 211 of the top foil 21 is a slanted plane and forms a convergence angle θ1 with the thrust disc 12, thereby quickly forming a high-pressure gas film. As shown, Figure 5 As shown, the structure corresponding to the wedge-shaped area 211 of the top foil 21 is the variable height area 222 of the first wave foil 22, the sizes of which are matched with each other, and the variable height area 222 provides support for the wedge-shaped area 211 of the top foil 21 to avoid deformation of the wedge-shaped area 211 of the top foil 21 itself.

[0059] The medium-stiffness bearing area 212 of the top foil 21 is a straight plane, forming a medium-stiffness bearing area with the thrust disk 12. During operation, the high-pressure gas film formed at the convergence angle θ1 enters this bearing area to support the thrust disk 12. The structure corresponding to the medium-stiffness bearing area 212 of the top foil 21 is the medium-stiffness corrugated foil bearing area 223. The two are matched in size. The medium-stiffness corrugated foil bearing area 223 provides support for the medium-stiffness bearing area 212 of the top foil 21, so that the medium-stiffness bearing area 212 of the top foil 21 undergoes a moderate deformation under the action of the high-pressure gas film.

[0060] like Figure 6 As shown, both the low-stiffness suspended bearing area 213 and the low-stiffness bearing area 214 of the top foil 21 are flat planes, forming a low-stiffness bearing area with the thrust plate 12. During operation, a high-pressure gas film from the medium-stiffness bearing area 212 of the top foil 21 enters this bearing area to support the thrust plate 12. The structure corresponding to the low-stiffness suspended bearing area 213 of the top foil 21 is the low-stiffness corrugated foil suspended area 232. The two have different dimensions, with the height of the low-stiffness corrugated foil suspended area 232 being smaller than the height of the low-stiffness suspended bearing area 213 of the top foil 21. There is a deformation space between them, allowing the low-stiffness suspended bearing area 213 of the top foil 21 to undergo the maximum deformation under the action of the high-pressure gas film. The structure corresponding to the low stiffness bearing area 214 of the top foil 21 is the low stiffness corrugated foil bearing area 233. The two are matched in size. The low stiffness corrugated foil bearing area 233 provides support for the low stiffness bearing area 214 of the top foil 21, so that the low stiffness bearing area 214 of the top foil 21 undergoes a large deformation under the action of high pressure gas film.

[0061] like Figure 7 As shown, the high-rigidity bearing area 215 of the top foil 21 is a straight plane, forming a high-rigidity bearing area with the thrust disk 12. During operation, high-pressure air films from the low-rigidity suspended bearing areas 213 and 214 of the top foil 21 enter this bearing area to support the thrust disk 12. The structure corresponding to the high-rigidity bearing area 215 of the top foil 21 is the high-rigidity corrugated foil bearing area 242. The two are matched in size, and the high-rigidity corrugated foil bearing area 242 provides support for the high-rigidity bearing area 215 of the top foil 21, so that the high-rigidity bearing area 215 of the top foil 21 only undergoes small deformation.

[0062] like Figure 5 As shown, the waveform height of the medium-stiffness corrugated foil bearing area 223 is H1, and the component thickness is T1; as Figure 6 As shown, the waveform height of the low-stiffness corrugated foil suspension area 232 is H2, and the component thickness is T2; the waveform height of the low-stiffness corrugated foil bearing area 233 is H3, and the component thickness is T2; as Figure 7As shown, the waveform height of the high-rigidity corrugated foil bearing area 242 is H4, and the component thickness is T3. For corrugated foil type hydrodynamic gas thrust bearings, the smaller the waveform height and the larger the material thickness, the greater the stiffness of the corrugated foil; conversely, the larger the corrugated foil height and the smaller the material thickness, the smaller the stiffness of the corrugated foil.

[0063] In the embodiments of this application, the structural dimensions of the three corrugated foils are as follows: T2 < T1 < T3, H3 = H1 = H4 > H2. The advantage of this thickness design scheme is that the corrugated foil structure is designed with three successively increasing stiffnesses—the second corrugated foil 23, the first corrugated foil 22, and the third corrugated foil 24—mainly by increasing the material thickness. Figure 10 As shown, along the rotation direction of the thrust disk, the first wave foil 22, the second wave foil 23, and the third wave foil 24 are distributed sequentially. The second wave foil 23 is mainly used to generate a secondary wedge effect. Therefore, overall, the high-pressure gas film flow direction is from the first wave foil 22 to the third wave foil 24. Since the structural stiffness of the first wave foil 22 is smaller than that of the third wave foil 24, under the same gas film pressure, the deformation of the first wave foil 22 is greater than that of the third wave foil 24, which further improves the wedge shape, enhances the dynamic pressure effect, and increases the bearing load capacity. The second foil 23 has the smallest component thickness, so under the same film pressure, it deforms the most, causing the low-stiffness bearing area 214 of the corresponding top foil 21 to "concave". The third foil 24, due to its highest stiffness, deforms very little, and the high-stiffness bearing area 215 of the corresponding top foil 21 also shows a small concavity. Therefore, along the rotation direction, the concavity of the low-stiffness bearing area 214 of the top foil 21 generates a secondary wedge effect, further enhancing the dynamic pressure effect of the film and strengthening the bearing capacity. Moreover, the higher the rotational speed, the greater the film pressure, and the greater the concavity of the low-stiffness bearing area 214 of the top foil 21, resulting in a stronger secondary wedge effect and a greater bearing capacity output. Thus, the secondary wedge effect in this embodiment adapts to changes in rotational speed, providing suitable film pressure for rotor systems at different speeds and reducing vibrations caused by dynamic pressure film fluctuations during rotational speed changes. Furthermore, the circumferential distance between adjacent foils matches the foil stiffness.

[0064] In this embodiment of the invention, the effect of the planar region of the top foil 21 corresponding to the second wave foil 23 being "concave" is defined as a regional secondary wedge effect.

[0065] like Figure 5 As shown, along the airflow direction, the circumferential safety distance L1 between the free end of the medium-stiffness corrugated foil bearing region 223 of the first corrugated foil 22 and the fixed end of the second straight edge region 231 of the second corrugated foil 23; as Figure 6As shown, along the airflow flowing direction, the free end of the low stiffness wave foil bearing area 233 is away from the fixed end of the third straight side area 241 by a circumferential safety distance L2, and since the structural stiffness of the second wave foil 23 is less than that of the first wave foil 22, the second wave foil 23 deforms more under the same gas film pressure, and the second wave foil 23 extends more along the free end circumferentially, thus L1 < L2 is required, and the specific value is determined according to the maximum load force borne by the bearing, and the circumferential safety distance should be greater than the circumferential extension of the wave foil after being compressed.

[0066] In one embodiment, the free end of the third wave foil 24 is located inside the active end of the top foil 21 and has a preset distance from the active end.

[0067] As shown, along the airflow flowing direction, the free end of the low stiffness wave foil bearing area 233 is away from the fixed end of the third straight side area 241 by a circumferential safety distance L2, and since the structural stiffness of the second wave foil 23 is less than that of the first wave foil 22, the second wave foil 23 deforms more under the same gas film pressure, and the second wave foil 23 extends more along the free end circumferentially, thus L1 < L2 is required, and the specific value is determined according to the maximum load force borne by the bearing, and the circumferential safety distance should be greater than the circumferential extension of the wave foil after being compressed. Figure 7 As shown, along the airflow flowing direction, the free end of the low stiffness wave foil bearing area 233 is away from the fixed end of the third straight side area 241 by a circumferential safety distance L2, and since the structural stiffness of the second wave foil 23 is less than that of the first wave foil 22, the second wave foil 23 deforms more under the same gas film pressure, and the second wave foil 23 extends more along the free end circumferentially, thus L1 < L2 is required, and the specific value is determined according to the maximum load force borne by the bearing, and the circumferential safety distance should be greater than the circumferential extension of the wave foil after being compressed.

[0068] The design of the height dimension H3 = H1 = H4 > H2 has the advantage that the initial heights of the medium stiffness bearing area 212 of the top foil 21, the low stiffness bearing area 214 of the top foil 21, and the high stiffness bearing area 215 of the top foil 21 are the same, and the bearing area formed by the thrust disc 12 is the sum of the three, especially in the low-speed case, since the rotational speed is not high, the gas film pressure is also not high, and the above three top foil height deformations are similar, at this time the bearing area is the sum of the three, and the bearing capacity of the bearing under the condition of low speed due to the low gas film pressure is compensated by increasing the bearing area. In addition, H2 < H3, so that the low stiffness suspended bearing area 213 of the top foil 21 is in an initial suspended state, and thus when the rotational speed is increased, the gas film pressure is also gradually increased, and under the action of the high-pressure gas film, the low stiffness suspended bearing area 213 of the top foil 21 will deform first by "sagging", at this time along the rotation direction, the low stiffness suspended bearing area 213 of the top foil 21 and the low stiffness bearing area 214 of the top foil 21 form a local secondary wedge-shaped structure, which can further increase the gas film pressure entering the high stiffness bearing area 215 of the top foil 21, thereby increasing the bearing capacity.

[0069] In one embodiment, the number of arched protrusions of the second wave foil 23 is two.

[0070] In the present embodiment, the number of arched protrusions of the second wave foil 23 is set to two, which can control the depth of the concave region formed by the second wave foil 23, and avoid the situation that the concave region is too deep to form effective dynamic pressure effect, and also make it more convenient to form the secondary wedge-shaped structure.

[0071] In one embodiment, the area of the first wave foil 22 is larger than that of the third wave foil 24, and the area of the third wave foil 24 is larger than that of the second wave foil 23.

[0072] In one embodiment, in order to be stressed evenly, the number of top foils 21 is even and evenly distributed circumferentially. In the present embodiment, the number of top foils 21 is four.

[0073] According to the embodiment of the present application, the rotor assembly comprises a rotating shaft 11, a thrust disc 12 and a dynamic pressure gas thrust bearing 2, the dynamic pressure gas thrust bearing 2 is any one of the dynamic pressure gas thrust bearings according to claims 1 to 14, the thrust disc 12 is fixedly arranged on the rotating shaft 11, the dynamic pressure gas thrust bearing 2 is arranged corresponding to the thrust disc 12, and the top surface of the top foil 21 faces the thrust disc 12.

[0074] In the present patent, the thrust disc 12 and the top foil 21 of the dynamic pressure gas thrust bearing form a matching surface with each other, the wedge-shaped area 211 of the thrust disc 12 and the top foil 21 form a convergence angle θ1. Figure 5 When working, the rotor 1 rotates at high speed under the action of the electromagnetic field of the motor stator, and when reaching the designed rotating speed, the gas film is formed by the dynamic pressure effect under the action of the convergence angle θ1, supporting the rotation of the rotor.

[0075] According to the embodiment of the present application, the compressor comprises the dynamic pressure gas thrust bearing or the rotor assembly described above.

[0076] It is to be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form, unless the context clearly indicates otherwise, and it should also be understood that, when the terms "comprise" and / or "include" are used in the specification, there is a presence of the features, steps, operations, devices, components and / or combinations thereof.

[0077] It should be noted that the terms "first", "second", and the like, used in the description and in the claims of the present application as well as above-mentioned figures are used to distinguish between similar objects and not necessarily for describing a specific sequential or chronological order. It is to be understood that the use of data so designated is not meant to limit a given item described by such data to the same category as other data designated by the same designations, but instead is so designated only for convenience as a means of discriminating between the two series of items that refer to a same data.

[0078] The preferred embodiments of the application described herein are examples of the present application and are not intended to limit the scope of the application. Various modifications and changes can be made thereto by those skilled in the art which freely adapt to the idea and principles of the application, without departing from the spirit and scope thereof, and it is to be understood that such modifications and changes are to be included within the scope of the application as defined by the appended claims.

Claims

1. A dynamic gas thrust bearing characterized by, Comprising: A bearing housing (25); A top foil (21) fixed at one end on the bearing housing (25) and movable at the other end relative to the bearing housing (25), forming a wave foil mounting space between the top foil (21) and the bearing housing (25); A first wave foil (22); A second wave foil (23); A third wave foil (24), the first wave foil (22), the second wave foil (23) and the third wave foil (24) are sequentially and spaced apart in the wave foil mounting space along the airflow direction, the rigidity of the first wave foil (22) and the third wave foil (24) is greater than the rigidity of the second wave foil (23); The rigidity of the first wave foil (22) is less than the rigidity of the third wave foil (24); The top foil (21) comprises a wedge-shaped area (211) and a flat area, part of the first wave foil (22) is located in the wedge-shaped area (211), and part of the first wave foil (22) is located in the flat area, the second wave foil (23) and the third wave foil (24) are located in the flat area.

2. The dynamic gas thrust bearing of claim 1, wherein, The first wave foil (22), the second wave foil (23) and the third wave foil (24) each comprise a fixed end and a free end, the fixed end is fixedly arranged on the bearing housing (25), and the free end is movable relative to the bearing housing (25), and the free end of the same wave foil is located on the downstream side of the fixed end in the airflow direction.

3. The dynamic gas thrust bearing of claim 1, wherein, The flat area comprises a medium rigidity bearing area (212), the first wave foil (22) comprises a first straight edge area (221), a variable height area (222) and a medium rigidity wave foil bearing area (223) arranged in sequence along the airflow direction, the first straight edge area (221) is fixedly connected with the bearing housing (25), the variable height area (222) is arranged corresponding to the wedge-shaped area (211), and the medium rigidity wave foil bearing area (223) is arranged corresponding to the medium rigidity bearing area (212) of the flat area.

4. The dynamic gas thrust bearing of claim 3, wherein, The flat area further comprises a low rigidity suspended bearing area (213) and a low rigidity bearing area (214), the second wave foil (23) comprises a second straight edge area (231), a low rigidity wave foil suspended area (232) and a low rigidity wave foil bearing area (233) arranged in sequence along the airflow direction, the second straight edge area (231) is fixedly connected with the bearing housing (25), a top portion of the low rigidity wave foil suspended area (232) and the top foil (21) form a predetermined interval, the low rigidity wave foil suspended area (232) is arranged corresponding to the low rigidity suspended bearing area (213) of the flat area, and the low rigidity wave foil bearing area (233) is arranged corresponding to the low rigidity bearing area (214) of the flat area.

5. The dynamic gas thrust bearing of claim 4, wherein, The second wave foil (23) has two arched protrusions.

6. A dynamic pressure gas thrust bearing according to any one of claims 3 to 5, wherein, The flat area further comprises a high rigidity bearing area (215), the third wave foil (24) comprises a third straight edge area (241) and a high rigidity wave foil bearing area (242), the third straight edge area (241) is fixedly connected with the bearing housing (25), and the high rigidity wave foil bearing area (242) is arranged corresponding to the high rigidity bearing area (215).

7. The dynamic gas thrust bearing of claim 1 wherein, The first wave foil (22), the second wave foil (23) and the third wave foil (24) are made of the same material, the first wave foil (22) has a thickness of T1, the second wave foil (23) has a thickness of T2, and the third wave foil (24) has a thickness of T3, T2 < T1 < T3.

8. The dynamic gas thrust bearing of claim 1, wherein, The first wave foil (22), the second wave foil (23) and the third wave foil (24) are made of different materials and have the same thickness, the material rigidity of the second wave foil (23) is less than that of the first wave foil (22), and the material rigidity of the first wave foil (22) is less than that of the third wave foil (24).

9. The dynamic gas thrust bearing of claim 2, wherein, The free end of the third wave foil (24) is located inside the movable end of the top foil (21) and has a preset distance from the movable end.

10. The dynamic gas thrust bearing of claim 1, wherein, The area of the first wave foil (22) is greater than that of the third wave foil (24), and the area of the third wave foil (24) is greater than that of the second wave foil (23).

11. The dynamic gas thrust bearing of claim 1, wherein, The bearing shell (25) is a ring-shaped flat plate, the top foil (21) is a plurality of and arranged in sequence along the circumference of the bearing shell (25), and the first wave foil (22), the second wave foil (23) and the third wave foil (24) are arranged correspondingly to the top foil (21).

12. The dynamic gas thrust bearing of claim 11, wherein, The number of the top foil (21) is even.

13. A rotor assembly comprising a rotor shaft (11), a thrust disc (12) and a hydrodynamic gas thrust bearing (2), characterized in that The dynamic pressure gas thrust bearing (2) is the dynamic pressure gas thrust bearing according to any one of claims 1 to 12, the thrust disc (12) is fixedly arranged on the rotating shaft (11), the dynamic pressure gas thrust bearing (2) is arranged correspondingly to the thrust disc (12), and the top surface of the top foil (21) faces the thrust disc (12).

14. A compressor characterized by, The dynamic pressure gas thrust bearing according to any one of claims 1 to 12 or the rotor assembly according to claim 13.

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