Air bearing assembly

Abstract

An air bearing assembly comprises a main shaft, the periphery of the main shaft is sleeved with a thrust plate and a shaft sleeve, a thrust piece is arranged between the thrust plate and a bearing shell, the bearing shell is arranged on the periphery of the shaft sleeve, a bearing seat is arranged on the periphery of the bearing shell, and a first air channel for providing radial loads is arranged between the shaft sleeve and the main shaft. A second air channel for providing axial load is arranged between the thrust plate and the side face of the bearing shell, and a displacement sensor for sensing the position of the thrust plate is arranged on the side face of the bearing shell. According to the air bearing assembly, the gap between the thrust plate and the thrust piece is detected through the displacement sensor, so that the air pressure of the first air channel and the air pressure of the second air channel are adjusted, and the high-speed and stable rotating performance of the air bearing assembly is improved.

Description

Technical Field

[0001] The utility model relates to the field of air floating bearings, in particular to an air floating bearing used in a centrifugal compressor. Background Art

[0002] Air bearings form an air film between the air bearing and the main shaft through gas. The gas enters the gap between the bearing and the rotor through the micropores on the bearing surface, forming air film pressure on the supporting parts of the rotor, thereby supporting the rotor to float. Compared with conventional oil-lubricated bearings, air bearings have more favorable characteristics, such as high speed, high precision, low power consumption, low vibration and noise, no pollution and long life. They are widely used in fluid machinery, machine tools, medical and other industries, especially in the fields of ultra-high-speed rotating machinery and ultra-precision machinery manufacturing. They have obvious advantages and can also work under extremely high or low temperature conditions.

[0003] At present, according to the lubrication form of air bearings, they are mainly divided into static pressure air bearings and dynamic pressure air bearings. Compared with dynamic pressure air bearings, the load-bearing capacity of static pressure air bearings is 5-9 times that of dynamic pressure air bearings, and it is independent of any relative movement between the bearing surfaces. It mainly relies on an external high-pressure air source to supply air to the bearing. The gas enters the bearing gap from the air source through a throttle, and then is continuously discharged from the outer edge of the bearing, so that the air film in the bearing gap obtains the load-bearing capacity (reference: JWPOWELL, Ding Weigang, Lin Xiangqun, etc., translated, "Air Static Pressure Bearing Design", National Defense Industry Press). The characteristics of air bearings are simple structure and easy maintenance, but the disadvantages are also very obvious. There are problems such as low load-bearing capacity, weak rigidity, micro-vibration and weak resistance to external interference. Due to the limitation of load-bearing capacity, the weight of the supported rotor cannot be too high. When the rotor starts and stops instantly, there may be a short-term contact, which is very likely to cause friction or wear of the moving and static parts, and high requirements are placed on the wear resistance of the contact surface of the air bearing.

[0004] According to patent CN210371677U, a three-way supported small-hole throttling air-floating bearing is disclosed. The bearing is composed of a radial bearing and a thrust bearing arranged on two thrust surfaces to form a composite bearing. Two thrust plates are arranged on the main shaft, and the composite bearing is arranged between the two thrust plates, and bears radial and axial loads at the same time. The static pressure air-floating bearing structures disclosed in patents CN204003975U and CN102494025A have similar characteristics. Two thrust surfaces and radial surfaces are processed on the main shaft. The two thrust surfaces and radial surfaces of the bearing are wrapped around the outside of the main shaft, and bear radial and axial loads at the same time. The air-floating bearing structures disclosed in the three patents have the common point that a radial bearing surface and two thrust bearing surfaces are used to form a composite bearing. Since the two thrust bearing surfaces are located on both sides of the radial bearing surface in an "H" shape, they are also called H-type air-floating bearings. As shown in patent CN113738661A, when the H-type air bearing is used in the centrifugal compressor shaft system, its supporting end must be equipped with an independent radial air bearing at the same time. The H-type air bearing and the radial air bearing are arranged on both sides of the motor rotor respectively, one end bears radial and axial loads, and the other end bears radial loads.

[0005] According to patent CN216343373U, a thrust air bearing assembly is disclosed, which has a structure of arranging a single thrust plate and double thrust surfaces on the main shaft. The two thrust surfaces of the thrust air bearing are arranged on both sides of the thrust plate. Since the thrust plate is thin, the distance between the two thrust surfaces is close, and the thrust air bearing is combined with the thrust air bearing to form an "I" shape, which is also called an I-type thrust bearing. As described in patents CN112628281A and CN106015032B, when an I-type thrust air bearing is used in a centrifugal compressor shaft system, its supporting end must be equipped with two independent radial air bearings at the same time. The shaft system supports both ends, and a thrust bearing and a radial bearing are arranged at one end to bear radial and axial loads, and a radial bearing is arranged at the other end to bear radial loads.

[0006] The structural features and shaft system layout of the H-type bearing and I-type bearing described above will cause two problems: the first problem is the problem of the bearing structure itself. The exhaust direction of the H-type bearing structure and the I-type bearing structure is the outer circle side of the thrust gap, and the air film pressure distribution in the thrust gap is correlated with the exhaust direction of the air film, which causes the pressure at the inner circle of the thrust bearing to be significantly higher than the pressure at the outer circle, and the pressure gradient is large. In addition, the thrust surface side of the H-type air-floating bearing also takes into account the exhaust of the radial gap gas. The gas in the thrust gap and the radial gap is closed. Since the gas exhaust direction is 90°, it is easy to form turbulence on the inner circle of the thrust surface, which will not only cause frictional heat to cause thermal deformation of the bearing body, but also easily destroy the laminar air film in the thrust gap, thereby causing thrust surface unbalanced load. In severe cases, the thrust plate and the thrust surface will rub against each other. When the friction temperature rises instantly, the thrust plate will fall off and the bearing will fail. The second problem is caused by the asymmetry of the rotor's structural layout. A thrust bearing and a radial bearing are arranged at one end of the main shaft, and a radial bearing is arranged alone at the other end. The loads borne by the two ends of the bearing support are quite different. For the rotor supported by the air bearing, since the gas viscosity is about 1 / 1000 of the oil viscosity, the thickness of the air film is very small. Even a slight disturbance from the outside can easily cause the rotor to become unstable. In severe cases, the main shaft and the bearing may come into contact, causing scratches or seizure. Therefore, extremely high requirements are placed on dynamic balancing, and the asymmetry of the rotor's structural layout is not conducive to the implementation of high-precision dynamic balancing technology.

[0007] The rotor structure of the centrifugal compressor adopts the static pressure air bearing. Since the weight of the rotor is usually constant, the load borne by the air bearing during operation is very stable, and the bearing is rarely damaged due to radial load. Since the centrifugal compressor has abnormal working conditions such as instantaneous start, instantaneous stop, sudden acceleration and sudden load change during operation, the axial load of the centrifugal compressor varies greatly and is very unstable. Therefore, in the design of the shaft system of the centrifugal compressor, the impellers are arranged back to back at both ends of the rotor to offset most of the axial thrust. However, a small part of the axial thrust is still borne by the thrust bearing. When the centrifugal compressor has abnormal working conditions, the bearing capacity, stiffness and damping of the bearing are not adjusted in time according to the abnormal situation, which leads to increased axial vibration of the centrifugal compressor. In severe cases, the thrust plate and the thrust bearing will collide and scratch, and even the thrust plate will fail due to heat and friction.

[0008] Patent CN203035757U also discloses an air bearing assembly for a high-speed electric spindle, which adopts a combination of a single thrust bearing and a radial bearing. The bearing shape is similar to the air bearing of the utility model. Two O-rings are arranged on the outer circle of the radial bearing to provide additional damping. Under high-speed rotation, the vibration of the rotor cannot be completely eliminated, and the throttle adopts a perforated plate type. Under small clearance conditions, it may be accompanied by an "air hammer" phenomenon. When the clearance is reduced to a certain extent, the bearing stiffness will collapse and the rotor operation will be extremely unstable.

[0009] Regarding the above-mentioned prior art, the object of research by those skilled in the art is to form an air-floating bearing assembly with stable air film and strong load-bearing capacity. Utility Model Content

[0010] The purpose of the utility model is to provide an air bearing assembly to address the defects and shortcomings of the prior art, so that the bearing has the function of automatically measuring the thrust clearance and controls the thrust clearance by actively adjusting the air supply pressure. For the bearing body, the reliability of the operation of the air bearing assembly is further improved through the reasonable design of the air duct and the optimization of its overall structure.

[0011] In order to achieve the above-mentioned purpose, the utility model provides an air-floating bearing assembly, including a main shaft, a thrust plate and a sleeve are respectively sleeved on the outer periphery of the main shaft, a bearing shell is arranged on the outer periphery of the sleeve, a thrust plate is arranged between the thrust plate and the bearing shell, a bearing seat is arranged on the outer periphery of the bearing shell, a first air passage for providing radial load is arranged between the sleeve and the main shaft, a second air passage for providing axial load is arranged between the thrust plate and the side of the bearing shell, a displacement sensor for sensing the position of the thrust plate is arranged on the side of the bearing shell, and the first air passage and the second air passage are connected to each other. This air-floating bearing assembly detects the gap between the thrust plate and the thrust plate through the displacement sensor, and adjusts the air pressure of the intake pipeline accordingly, so as to realize the pressure control of the first air passage and the second air passage of the air-floating bearing assembly, and avoid the accidental wear caused by the change of the gap between the main shaft, the thrust plate and the sleeve caused by the pressure change of the first air passage and the second air passage.

[0012] The first air channel includes an air inlet hole provided in the bearing seat, the air inlet hole is connected to a first groove located on the inner side of the bearing seat, the first groove is connected to a radial air inlet hole and an axial air inlet hole in the bearing shell, the radial air inlet hole is connected to an air groove inlet port of the sleeve, a radial gap is formed between the sleeve and the main shaft, the sleeve is a porous gas-permeable medium, and the gas in the air groove inlet port is connected to the radial gap. Under the action of gravity load, the main shaft is eccentric relative to the sleeve, the radial gap around the outer cylindrical surface of the main shaft is not uniform, forming an upper gap and a lower gap, the two are connected to each other and the average value of the upper gap is greater than the average value of the lower gap, and an air film with a certain bearing capacity is formed in the gap to envelop the circumference of the main shaft, so that the floating operation of the main shaft in the sleeve is realized.

[0013] The sleeve includes a first annular surface and a second annular surface at both ends. A transverse air groove and a longitudinal annular air groove connected to the air groove inlet are arranged between the first annular surface and the second annular surface. The transverse air groove and the longitudinal annular air groove are evenly distributed on the outer circumference of the sleeve so that the gas at the air groove inlet can pass through the sleeve into the radial gap. A certain number of air grooves are arranged on the sleeve, which is conducive to better distribution of gas on the outer cylindrical surface of the sleeve. The porous gas-permeable medium has very uniform air permeability, which is conducive to forming a uniform gas mold in the radial gap and providing a stable gas film pressure. The sleeve adopts a fully porous medium as a throttle, and is also suitable for partially porous medium throttles. In addition, other forms of throttles such as small hole or micropore throttles, slit throttles, etc. are also applicable.

[0014] The bearing shell includes a first radial annular surface located on the inner side of the bearing shell and a second groove located on the outer periphery of the bearing shell. Radial glue storage grooves are provided on both sides of the first radial annular surface. The radial glue storage grooves are connected to the glue injection holes. Adhesive is injected into the radial glue storage grooves through the glue injection holes. The adhesive fills the glue storage grooves to firmly bond the sleeve and the bearing shell together.

[0015] The second air passage includes an axial annular air groove located on the side of the bearing shell, the axial annular air groove is connected to the axial air inlet hole, the gas in the axial annular air groove passes through the thrust plate and enters the axial gap between the thrust plate and the thrust plate, and the axial gap is connected to the second exhaust hole of the bearing seat. The air film with a certain bearing capacity formed by the axial gap has an effective thickness that avoids contact or wear between the thrust plate and the thrust plate, thereby extending the service life of the air bearing assembly.

[0016] The first annular glue storage groove and the second annular glue storage groove are respectively provided on both sides of the axial annular gas groove, the first radial gas groove is connected between the axial annular gas groove and the first annular glue storage groove, and the second radial gas groove is connected between the axial annular gas groove and the second annular glue storage groove. The first annular glue storage groove and the second annular glue storage groove are coated with adhesive to firmly bond the thrust plate and the bearing shell together to prevent the thrust plate from falling off under a certain intake pressure. The first radial gas groove and the second radial gas groove are distributed in a scattered manner, which is conducive to the uniform permeation of the gas through the thrust plate, forming an air film with uniform pressure distribution in the axial gap, and ensuring that sufficient axial bearing capacity is provided.

[0017] The main shaft, thrust plate, sleeve and bearing shell surround each other to form a first cavity, the outer periphery of the thrust plate is installed with a sealing end cover, the sealing end cover, bearing shell and bearing seat surround each other to form a second cavity, the first cavity and the second cavity are connected through the axial gap and the first exhaust hole in the bearing shell, that is, the first air channel and the second air channel are connected to each other, ensuring that the air bearing assembly has stable and interconnected air intake and exhaust channels. The arrangement of the first exhaust hole is conducive to the timely discharge of gas in the axial gap and the radial gap, and can take away the heat generated by gas friction in the gap in time, thereby reducing the working temperature of the air film in the gap, eliminating a series of problems caused by thermal stress or thermal expansion, especially for the thrust plate, it helps to improve the overturning stiffness, the bearing capacity will be more stable, and can effectively reduce the risks brought about by abnormal working conditions of the compressor.

[0018] A sealing gap is provided between the sealing end cover and the thrust plate.

[0019] By adopting the above technical solution, the air bearing assembly detects the gap between the thrust plate and the thrust piece through the displacement sensor, and adjusts the air pressure of the intake pipeline accordingly, thereby realizing pressure control of the first air channel and the second air channel of the air bearing assembly, and improving the high-speed and stable rotation performance of the air bearing assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 This is a structural schematic diagram of an air bearing assembly of the utility model;

[0022] Figure 2 This is a schematic diagram of an air bearing assembly of the utility model;

[0023] Figure 3 for Figure 1 A partial enlarged view of the middle part;

[0024] Figure 4 This is a three-dimensional cross-sectional schematic diagram of the bearing shell in the utility model;

[0025] Figure 5 This is a schematic diagram of the three-dimensional structure of the central shaft sleeve of the utility model;

[0026] Figure 6 This is a schematic diagram of the thrust piece and the shaft sleeve installation structure in the utility model;

[0027] Figure 7 This is a schematic diagram of the arrangement of the symmetrical rotor air bearings in the utility model;

[0028] Figure 8 This is the schematic diagram of radial bearing principle of the middle shaft sleeve of the utility model;

[0029] Fig. 9 for Figure 8 Middle BB section view;

[0030] Fig.10 This is a schematic diagram of the axial bearing principle of the thrust piece in the utility model. DETAILED DESCRIPTION

[0031] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0032] like Figure 1-10 As shown, an air bearing assembly includes a main shaft 1, a thrust plate 9 and a sleeve 2 are respectively sleeved on the outer periphery of the main shaft 1, a bearing shell 3 is arranged on the outer periphery of the sleeve 2, a thrust plate 7 is arranged between the thrust plate 9 and the bearing shell 3, a bearing seat 5 is arranged on the outer periphery of the bearing shell 3, a first air passage for providing radial load is arranged between the sleeve 2 and the main shaft 1, a second air passage for providing axial load is arranged between the thrust plate and the side 3p of the bearing shell, a displacement sensor 6 for sensing the position of the thrust plate is arranged on the side 3p of the bearing shell, and the displacement sensor 6 is installed in the mounting hole 3k of the side 3p of the bearing shell, and the first air passage and the second air passage are connected to each other. The thrust plate 7 and the sleeve 2 are arranged vertically in a "T" shape, and bear the axial load and radial load respectively. T-type air bearings are used in pairs, and the two bearings have the same size specifications, which can achieve interchangeability, and the main shaft characteristics require symmetrical arrangement. Bearing shells 3, thrust plates 9 and impellers 54 are arranged on both sides of the main shaft 1. The thrust plate 7 is annular, and the sleeve 2 is cylindrical, and both have a certain thickness.

[0033] As a preferred air-floating bearing assembly, it is connected to a bearing air supply system, which includes an intake pipeline for providing an intake pressure Po for the first air duct and a controller 13. The controller 13 adjusts the intake pressure Po to control the air duct pressures of the first air duct and the second air duct respectively according to the sensed displacement sensor data and the exhaust pressure Pa of the first air duct.

[0034] The air intake pipeline includes a pressure pump 14 , a storage tank 15 , a regulating valve 17 , a flow meter 18 , and a second pressure sensor 19 connected by the pipeline; a heater 20 and a liquid level meter 21 are arranged inside the storage tank 15 , and a first pressure sensor 16 is connected to the outside of the storage tank 15 .

[0035] The first air passage includes an air inlet hole 5b provided on the bearing seat 5, the air inlet hole 5b is connected to the first groove 5a located inside the bearing seat 5, the first groove 5a is connected to the radial air inlet hole 3b and the axial air inlet hole 3c in the bearing shell 3, the radial air inlet hole 3b is connected to the air groove air inlet 2c of the shaft sleeve 2, a radial gap q2 is formed between the shaft sleeve 2 and the main shaft 1, the shaft sleeve 2 is a porous gas-permeable medium, and the gas in the air groove air inlet 2c is connected to the radial gap q2. A second groove 5d is provided on the side of the bearing seat 5, the second groove 5d is annular and the second O-ring 12 is arranged axially, and the exhaust notch of the first groove 5a is chamfered to form an inclined surface 5e, so as to improve the connectivity between the first groove 5a and the radial air inlet hole 3b. Because the main shaft 1 is eccentric relative to the sleeve 2 under the action of the gravity load (G), the radial clearance (q2) around the outer cylindrical surface of the main shaft (1) is not uniform, forming an upper clearance (q2a) and a lower clearance (q2b), which are interconnected and the average value of the upper clearance (q2a) is greater than the average value of the lower clearance (q2b). The main function of the inclined surface 5e is to facilitate the first O-ring to pass through the first groove smoothly during the assembly of the bearing shell, and to prevent the first O-ring from being scratched when it is installed.

[0036] The thrust plate 9 is sleeved on the main shaft 1 and arranged on the outside of the thrust plate 7 to form an axial gap q1. The bearing must ensure the minimum gap range of the axial gap q1 and the radial gap q2 during operation to prevent the sleeve 2 from contacting the main shaft 1 and the thrust plate 7 from contacting the thrust plate 9.

[0037] The second air duct includes an axial annular air groove 3d located on the side 3p of the bearing shell. The axial annular air groove 3d is connected to the axial air inlet hole 3c. The gas in the axial annular air groove 3d passes through the thrust plate 7 and enters the axial gap q1 between the thrust plate 9 and the thrust plate 7. The axial gap q1 is connected to the second exhaust hole 5c of the bearing seat 5.

[0038] The sleeve 2 comprises a first annular surface 2a and a second annular surface 2e at both ends, and a transverse air groove 2b and a longitudinal annular air groove 2d connected to an air groove air inlet 2c are arranged between the first annular surface 2a and the second annular surface 2e. The sleeve 2 is cylindrical and has a long length.

[0039] The bearing shell 3 includes a first radial annular surface 3r located on the inner side of the bearing shell 3 and a second groove 3a located on the outer periphery of the bearing shell 3. The second groove 3a cooperates to install the first O-ring 4. Radial glue storage grooves 3o are provided on both sides of the first radial annular surface 3r, and the radial glue storage grooves 3o are connected to the glue injection holes 3n.

[0040] The second air duct includes an axial annular air groove 3d located on the side surface 3p of the bearing shell. The axial annular air groove 3d is connected to the axial air inlet hole 3c. The gas in the axial annular air groove 3d passes through the thrust plate 7 and enters the axial air gap q1 between the thrust plate 9 and the thrust plate 7. The axial air gap q1 is connected to the second exhaust hole 5c of the bearing seat 5.

[0041] A first annular glue storage groove 3i and a second annular glue storage groove 3j are respectively provided on both sides of the axial annular gas groove 3d, a first radial gas groove 3e is connected between the axial annular gas groove 3d and the first annular glue storage groove 3i, and a second radial gas groove 3f is connected between the axial annular gas groove 3d and the second annular glue storage groove 3j. A certain number of the second radial gas grooves 3f and the first radial gas grooves 3e are arranged crosswise in a radial scattering manner, which is conducive to the uniform permeation of the gas through the thrust plate 7, forming a gas film with uniform pressure distribution in the axial gap q1, and ensuring that sufficient axial bearing capacity is provided. The thrust plate 7 is arranged on the outer side of the first radial gas groove 3e and the second radial gas groove 3f, and a sufficient amount of adhesive is applied to the first annular glue storage groove 3i and the second annular glue storage groove 3j in a "V" shape, so as to bond the thrust plate 7 and the bearing shell 3 together, and ensure that the side surface 3p of the bearing shell is slightly lower than the thrust plate 7.

[0042] As a preferred structure, the main shaft 1, the thrust plate 9, the sleeve 2 and the bearing shell 3 surround each other to form a first cavity 10, the outer periphery of the thrust plate 9 is provided with a sealing end cover 8, the sealing end cover 8, the bearing shell 3 and the bearing seat 5 surround each other to form a second cavity 11, and the first cavity 10 and the second cavity 11 are connected through the axial gap q1 and the first exhaust hole 3g in the bearing shell 3. A certain number of the first exhaust holes 3g are arranged in a radially scattered manner along the bearing shell 3. A sealing gap q3 is provided between the sealing end cover 8 and the thrust plate 9.

[0043] The utility model is an air-floating bearing assembly: the gas of the bearing air supply system enters the bearing shell through the air inlet hole 5b and the first groove 5a, wherein the first airway gas enters the transverse air groove 2b and the longitudinal annular air groove 2d of the shaft sleeve 2 in sequence through the radial air inlet hole 3b, and the gas is discharged from the radial gap q2 after penetrating and throttling through the shaft sleeve 2, and the second airway gas enters the axial annular air groove 3d in sequence through the axial air inlet hole 3c, passes through the first radial air groove 3e and the second radial air groove 3f, and finally passes through the thrust plate 7 and penetrating and throttling and is discharged from the axial gap q1, a part of the gas discharged from the axial gap q1 enters the first cavity 10, and the other part is divided into two paths, one path is discharged through the sealing gap q3, and the other path directly enters the second cavity 11 and mixes with the gas of the first exhaust hole 3g, and then is discharged through the second exhaust hole 5c. The first airway gas is discharged along the two sides of the shaft sleeve 2 through the radial gap q2, and one side is directly discharged through the first cavity 10, the first exhaust hole 3g, the second cavity 11 and the second exhaust hole 5c.

[0044] As a control method of the controller 13, the intake pressure Po passes through the sleeve 2 and the thrust plate 7 to generate penetration pressure at the radial gap q2 and the axial gap q1, wherein the penetration pressure Ps at the upper gap q2a, the penetration pressure Pn at the lower gap q2b, and the penetration pressure Pz at the average radius of the axial gap q1, the pressures Ps, Pn and Pz are adjusted by the pressure difference between the intake pressure Po and the exhaust pressure Pa.

[0045] The gap of the air bearing is in a cubic relationship with the flow rate. The larger the gap, the greater the exhaust flow rate and the smaller the exhaust resistance. Since the gap q2a>q2b, the pressure Ps<Pn is caused, and the corresponding bearing capacity acting on the upper and lower parts of the main shaft 1 is L×D×(Ps-Pa)<L×D×(Pn-Pa). The main shaft 1 is floated under the action of the upper and lower bearing capacity difference. The larger the intake pressure Po, the larger the pressure Ps and Pn, the smaller the upper and lower bearing capacity difference of the main shaft 1, the stronger the bearing capacity of the sleeve 2, and the closer the center line of the main shaft 1 is to the center line of the sleeve 2. For safety reasons, the radial clearance q2 must be guaranteed to be greater than a certain minimum value. L is the length of the sleeve 2, D is the diameter of the main shaft 1, and the corresponding functional relationship between the radial load and the radial clearance q2 is established through experiments.

[0046] The bearing capacity acting on the thrust piece 7 is π×(Pz-Pa)×(Ro2-Ri2). The greater the intake pressure Po, the greater the pressure Pz, and the greater the corresponding bearing capacity. The axial thrust load of the centrifugal compressor varies greatly, so the minimum safety distance of the axial gap q1 must be guaranteed. The axial gap q1 is detected by a certain number of displacement sensors 6, and the intake pressure Po is adjusted according to the detected value. Ro is the outer diameter of the thrust piece 7, and Ri is the inner diameter of the thrust piece 7. The corresponding functional relationship between the axial load and the axial gap q1 is established through experiments.

[0047] The controller 13 receives signals from the displacement sensor 6, the intake pressure Po, the exhaust pressure Pa, and the pressure Pc of the storage tank 15. After receiving the signal from the displacement sensor 6, the controller 13 determines whether it is within a reasonable range. If the axial clearance q1 is too small, the controller 13 issues an adjustment command to control the opening of the regulating valve 17 to increase the Po value. The larger the intake and exhaust pressure difference Po-Pa, the larger the axial clearance q1, the closer the value of the upper clearance q2a and the lower clearance q2b of the radial clearance q2, and the stronger the bearing capacity of the air bearing. On the contrary, the intake and exhaust pressure difference Po-Pa is not the larger the better. Although the larger the clearance of the air bearing, the greater its bearing capacity, the stiffness of the bearing will be weakened accordingly, and the ability to resist external disturbances will be weakened. Therefore, according to the actual operation of the bearing, the controller 13 will control the intake and exhaust pressure difference Po-Pa to fluctuate within a certain range.

[0048] The first pressure sensor 16 detects the pressure in the storage tank 15. If the pressure Pc is too low, in order to ensure that Pc>Po, the controller 13 needs to issue an instruction to start the heater 20 to heat the gas to increase its pressure. The liquid level meter 21 is used to detect the liquid level of the liquid in the storage tank 15. If the liquid level is too low, the controller 13 issues an instruction to start the pressure pump 14 to supply liquid until a certain liquid level is reached. In addition, the liquid level meter also has a temperature measurement function and can timely reflect the temperature of the fluid in the storage tank.

[0049] Since the thrust plate and the shaft sleeve share a common air supply system, when the axial air gap q1 is adjusted, the air supply pressure difference (Po-Pa) of the two is the same. Since the bearing capacity of the shaft sleeve has fully considered the change of the axial load at the beginning of the selection and design, when the axial load is adjusted, although the radial load is also adjusted synchronously, the bearing capacity of the shaft sleeve supports the radial load of the entire rotor relative to the axial load, leaving enough margin.

[0050] The utility model adopts a sleeve and a thrust piece to form an air bearing assembly capable of bearing radial load and axial load. The thrust piece is arranged perpendicular to the center line of the sleeve and is in a "T" shape. The structural form of the T-type air bearing is more conducive to the use of a symmetrical shaft system layout. The two supporting points of the rotor can be respectively arranged with air bearings of the same specification and size. The loads borne by each air bearing are similar, and the two can be interchanged, which is conducive to arranging production and reducing the manufacturing cost of the air bearing.

[0051] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art can change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An air bearing assembly, comprising a main shaft (1), characterized in that: The outer circumference of the main shaft (1) is respectively sleeved with a thrust plate (9) and a shaft sleeve (2); the outer circumference of the shaft sleeve (2) is provided with a bearing shell (3); a thrust plate (7) is provided between the thrust plate (9) and the bearing shell (3); the outer circumference of the bearing shell (3) is provided with a bearing seat (5); a first air passage for providing a radial load is provided between the shaft sleeve (2) and the main shaft (1); a second air passage for providing an axial load is provided between the thrust plate and the side surface (3p) of the bearing shell; a displacement sensor (6) for sensing the position of the thrust plate is provided on the side surface (3p) of the bearing shell; and the first air passage and the second air passage are communicated with each other.

2. An air bearing assembly according to claim 1, characterized in that: The first air passage comprises an air inlet hole (5b) provided on the bearing seat (5), the air inlet hole (5b) being connected to a first groove (5a) located on the inner side of the bearing seat (5), the first groove (5a) being connected to a radial air inlet hole (3b) and an axial air inlet hole (3c) in the bearing shell (3), the radial air inlet hole (3b) being connected to an air groove air inlet port (2c) of the shaft sleeve (2), a radial gap (q2) being formed between the shaft sleeve (2) and the main shaft (1), the shaft sleeve (2) being a porous air-permeable medium, and the gas in the air groove air inlet port (2c) being connected to the radial gap (q2).

3. An air bearing assembly according to claim 2, characterized in that: Under the action of the gravity load (G), the main shaft (1) is eccentric relative to the shaft sleeve (2), and the radial clearance (q2) around the outer cylindrical surface of the main shaft (1) is uneven, forming an upper clearance (q2a) and a lower clearance (q2b), and the average value of the upper clearance (q2a) is greater than the average value of the lower clearance (q2b).

4. The air bearing assembly according to claim 3, characterized in that: The shaft sleeve (2) comprises a first annular surface (2a) and a second annular surface (2e) located at two ends, and a transverse air groove (2b) and a longitudinal annular air groove (2d) connected to an air groove air inlet (2c) are provided between the first annular surface (2a) and the second annular surface (2e).

5. The air bearing assembly according to claim 1, characterized in that: The bearing shell (3) comprises a first radial annular surface (3r) located on the inner side of the bearing shell (3) and a second groove (3a) located on the outer periphery of the bearing shell (3), radial rubber storage grooves (3o) are provided on both sides of the first radial annular surface (3r), and the radial rubber storage grooves (3o) are connected to the rubber injection holes (3n).

6. The air bearing assembly according to claim 1, characterized in that: The second air passage comprises an axial annular air groove (3d) located on the side surface (3p) of the bearing shell, the axial annular air groove (3d) being connected to the axial air inlet hole (3c), the gas in the axial annular air groove (3d) passing through the thrust plate (7) and entering the axial gap (q1) between the thrust plate (9) and the thrust plate (7), and the axial gap (q1) being connected to the second air exhaust hole (5c) of the bearing seat (5).

7. An air bearing assembly according to claim 6, characterized in that: A first annular glue storage groove (3i) and a second annular glue storage groove (3j) are respectively provided on both sides of the axial annular gas groove (3d); a first radial gas groove (3e) is connected between the axial annular gas groove (3d) and the first annular glue storage groove (3i); and a second radial gas groove (3f) is connected between the axial annular gas groove (3d) and the second annular glue storage groove (3j).

8. The air bearing assembly according to claim 1, characterized in that: The main shaft (1), thrust plate (9), shaft sleeve (2) and bearing shell (3) surround each other to form a first cavity (10); a sealing end cover (8) is installed on the outer periphery of the thrust plate (9); the sealing end cover (8), bearing shell (3) and bearing seat (5) surround each other to form a second cavity (11); the first cavity (10) and the second cavity (11) are connected via an axial gap (q1) and a first exhaust hole (3g) in the bearing shell (3).

9. An air bearing assembly according to claim 8, characterized in that: A sealing gap (q3) is provided between the sealing end cover (8) and the thrust plate (9).

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