Gas-lubricated centrifugal refrigerant compressor

Abstract

The application provides a compressor, belonging to the technical field of compressors, in particular to an air-floating centrifugal refrigerant compressor, which comprises a motor shell, a motor stator, a compressor rotor part, an air-floating bearing, a volute and a motor end cover; cooling air supply of the air-floating bearing at the gas inlet end of the main shaft comes from gas leaked into the motor shell from the back of the impeller; liquid coolant can enter the motor cooling channel on the motor shell and cool the motor stator and the main shaft, and the liquid coolant is vaporized after absorbing heat and enters the first cavity in the motor shell; cooling air supply of the air-floating bearing at the gas return end of the main shaft comes from gas input into the first cavity from the motor cooling channel and gas from the gas inlet end of the main shaft. The air-floating centrifugal refrigerant compressor solves the problems of air supply and heat dissipation of the air-floating bearing through special bearing air supply design and axial force balance design, realizes balance of the axial force of the compressor rotor part, and makes the structure of the compressor more simple and compact.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of impellers, in particular to a gas bearing centrifugal refrigerant compressor. BACKGROUND

[0002] The refrigeration and air conditioning industry, as an important part of modern industry and daily life, its technology development and innovation has always been concerned. As an important part of the refrigeration system, the performance and efficiency of centrifugal refrigerant compressor is directly related to the operation effect of the whole refrigeration system. In recent years, with the improvement of energy saving and environmental protection consciousness and the continuous progress of technology, oil-free two-stage compression magnetic suspension, gas suspension compressor gradually becomes the mainstream product in the market. However, in practical application, for different application scenarios, there are still some problems, such as operation stability, energy efficiency ratio, cost, etc. There is still room for improvement.

[0003] The conventional magnetic suspension or gas suspension usually adopts the form of two-stage compressor. When the compressor is applied, the economizer can be configured on the system to improve the operation efficiency of the refrigeration system, which is usually called the way of supplementing air and increasing enthalpy. However, the performance improvement brought by supplementing air and increasing enthalpy is mainly for the working condition with large compression ratio. For some specific industry applications, such as oxidation industry, data center cooling, etc., the equipment often runs at high evaporation temperature, and the compression ratio of the compressor is low. The configuration of economizer is often redundant, and when running at low pressure ratio, the unloading of two-stage compressor is more difficult. Due to the configuration of one more impeller and its parts, it not only becomes a disadvantage in cost, but also brings negative effects in performance. Under similar specific working conditions, the compressor still has room for improvement.

[0004] Another reason why the conventional magnetic suspension or gas suspension compressor adopts two-stage compression is that the impellers are arranged in a left-right back-to-back manner to balance the aerodynamic axial force of the impeller, so as to reduce the load of the thrust bearing of the compressor and ensure the normal operation of the compressor. SUMMARY

[0005] Therefore, the present application provides a gas bearing centrifugal refrigerant compressor, which solves the problems of gas supply and heat dissipation of gas bearing through special bearing gas supply design and axial force balance design, and realizes the balance of axial force of the compressor rotor part, so that the structure of the compressor is more simple and compact.

[0006] In order to achieve the above purpose, the present application provides the following technical scheme:

[0007] A gas bearing centrifugal refrigerant compressor, comprising:

[0008] A motor housing, a motor stator, a compressor rotor part, a first gas bearing radial bearing, a second gas bearing radial bearing, a gas bearing thrust bearing, a volute and a motor end cover.

[0009] The motor stator and the compressor rotor are respectively installed inside the motor housing. The remaining space after the motor stator and the compressor rotor are arranged in the inner cavity of the motor housing forms a first cavity. The volute and the motor end cover are respectively arranged at both ends of the motor housing in the axial direction.

[0010] The compressor rotor includes a main shaft and an impeller, and the main shaft is rotatably connected to the motor housing via a first air-bearing radial bearing and a second air-bearing radial bearing.

[0011] The main shaft includes an air inlet end disposed on one side of the first air-bearing radial bearing and the air-bearing thrust bearing, a middle section disposed of a magnet, and an air return end disposed on one side of the second air-bearing radial bearing. The air inlet end of the main shaft extends out of the axial end of the motor housing, and the impeller is disposed on the air inlet end of the main shaft and located between the axial end of the motor housing and the volute.

[0012] The cooling air supply at the air inlet end of the main shaft comes from the gas leaking into the motor housing from behind the impeller;

[0013] The motor housing is also provided with a motor cooling channel, which is connected to the first cavity. Liquid coolant can enter the motor cooling channel and cool the motor housing. After absorbing heat and vaporizing, the liquid coolant enters the first cavity.

[0014] The cooling air supply to the return air end of the spindle comes from the gas input into the first cavity from the motor cooling channel and the gas from the intake air end of the spindle.

[0015] Optional components also include bearing housings, backplate seals, and wheel cover seals;

[0016] The bearing housing is installed at one end of the motor housing, and the first air-floating radial bearing and the second air-floating radial bearing are respectively installed in the bearing housing and the motor housing;

[0017] The back plate is sealed at the back of the impeller and is mounted on the bearing housing by screws; the wheel cover is sealed at the wheel cover of the impeller and is mounted on the volute by screws.

[0018] Optionally, the compressor rotor section further includes a thrust disc, a bushing, and a lock nut;

[0019] The air inlet of the main shaft passes through the first air-bearing radial bearing, the middle section of the main shaft passes through the motor stator, and the exhaust end of the main shaft passes through the second air-bearing radial bearing.

[0020] The thrust plate is disposed at the air inlet end of the main shaft, and the air-bearing thrust bearing is installed between the bearing housing and the back plate seal and is located on both sides of the thrust plate in the axial direction.

[0021] The bushing is sleeved on the main shaft, with one axial end of the bushing abutting against the end face of the thrust disc; the other axial end of the bushing abutting against the back of the impeller; the impeller cover contacts the lock nut and is fixed by the frictional force generated by the stretching deformation of the pull rod and the locking torque of the lock nut.

[0022] The backplate seal is fitted onto the bushing, and the radial gap between the backplate seal and the bushing forms an airflow channel.

[0023] Optionally, the airflow channel formed by the radial gap between the bushing and the back plate seal is the air inlet cooling channel. The gas leaking from behind the impeller flows through the air inlet cooling channel to the thrust plate, the air-bearing thrust bearing and the first air-bearing radial bearing, and then flows to the first cavity in the motor housing.

[0024] Optionally, the motor housing is provided with a cooling liquid inlet, which is connected to the spiral motor cooling channel. The motor cooling channel is connected to the first cavity inside the motor housing. Coolant can enter from the cooling liquid inlet and vaporize when passing through the motor cooling channel and enter the first cavity.

[0025] Optionally, the radial gap between the motor stator and the compressor rotor forms a main shaft cooling channel. Cooling gas passing through the thrust plate, the air-bearing thrust bearing, and the first air-bearing radial bearing reaches the first cavity and mixes with cooling gas from the motor cooling channel to the first cavity. The mixture then passes through the main shaft cooling channel to cool the middle section of the main shaft where magnets are located.

[0026] Optionally, the airflow channel formed by the radial clearance between the second air-bearing radial bearing and the main shaft is the return air cooling channel. Cooling gas flows from the main shaft cooling channel to the return air cooling channel to supply air and cool the second air-bearing radial bearing.

[0027] Optionally, the cooling gas of the second air-bearing radial bearing flows to the second cavity formed by the motor housing and the motor end cover, and is discharged from the return gas outlet provided on the motor end cover.

[0028] Optionally, the air supply to the first air-bearing radial bearing, the air-bearing thrust bearing, and the thrust disk is controlled by the pressure difference between the impeller back outlet and the first cavity.

[0029] The air supply to the second air-bearing radial bearing is controlled by the pressure difference between the return air outlet on the motor end cover and the first cavity.

[0030] Optionally, it also includes an inlet guide vane adjustment mechanism, which is mounted on the volute by screws. The inlet guide vane adjustment mechanism includes an actuator and a drive shaft. The actuator can drive the drive shaft to open and close the guide vane blades at the air inlet of the air-float centrifugal refrigerant compressor and adjust the gas flow.

[0031] The air-floating centrifugal refrigerant compressor provided in this application adopts a single-stage compressor form, which reduces the number of parts, not only improving the operating efficiency of the compressor, but also reducing the cost of the compressor and achieving a better cost performance. Since there is only one end of the air intake, in order to ensure the air supply and cooling of the air-floating radial bearings and air-floating thrust bearings at both ends of the main shaft, a specific bearing air supply structure design is used to solve the heat dissipation problem of the air-floating bearings, making the compressor structure simpler and more compact. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0033] Figure 1 This is the general layout diagram of the air-float centrifugal refrigerant compressor of this application;

[0034] Figure 2 This is a schematic diagram of the compressor rotor section of this application;

[0035] Figure 3 This is a schematic diagram of the cooling system of this application.

[0036] exist Figures 1-3 middle:

[0037] 1. Motor housing; 2. Motor stator; 3. Compressor rotor; 4. First air-bearing radial bearing; 5. Second air-bearing radial bearing; 6. Bearing housing; 7. Back plate seal; 8. Wheel cover seal; 9. Volute; 10. Motor end cover; 11. Inlet guide vane adjustment mechanism; 12. Second cavity; 13. First cavity; 14. Actuator; 15. Drive shaft;

[0038] 16. Impeller; 17. Main shaft; 18. Thrust disc; 19. Bushing; 20. Lock nut;

[0039] 21. Inlet cooling channel; 22. Motor cooling channel; 23. Return air cooling channel; 24. Spindle cooling channel; 25. Coolant inlet; 26. Return air outlet. Detailed Implementation

[0040] This application provides an air-float centrifugal refrigerant compressor, which solves the air supply and heat dissipation problems of the air-float bearing through a special bearing air supply design and axial force balance design, and also achieves the balance of axial force in the compressor rotor, making the compressor structure simpler and more compact.

[0041] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] like Figure 1 As shown, the air-float centrifugal refrigerant compressor provided in this application includes:

[0043] Motor housing 1, motor stator 2, compressor rotor 3, first air-bearing radial bearing 4, second air-bearing radial bearing 5, air-bearing thrust bearing, volute 9, and motor end cover 10.

[0044] The motor stator 2 is heat-fitted into the motor housing 1, and the lead wires of the motor stator 2 are led out through the openings on the motor housing 1 to the junction box and connected to the sealed junction plate;

[0045] The compressor rotor 3 is rotatably connected to the motor housing 1. Specifically, the compressor rotor 3 includes a main shaft 17 and an impeller 16. The middle section of the main shaft 17 passes through the motor stator 2, and both ends are rotatably connected to the motor housing 1 through a first air-floating radial bearing 4 and a second air-floating radial bearing 5 installed in the motor housing 1.

[0046] The remaining space after the motor stator 2 and the compressor rotor 3 are installed in the inner cavity of the motor housing 1 forms the first cavity 13. The volute 9 and the motor end cover 10 are respectively installed at both ends of the motor housing 1 in the axial direction. The volute 9 is positioned and installed through the end face of the motor housing 1 to ensure concentricity with the compressor rotor 3.

[0047] The main shaft 17 includes an air inlet end disposed on one side of the first air-bearing radial bearing 4 and the air-bearing thrust bearing, a middle section disposed of a magnet, and an air return end disposed on one side of the second air-bearing radial bearing 5. The air inlet end of the main shaft 17 extends out of the axial end of the motor housing 1, and the impeller 16 is disposed at the air inlet end of the main shaft 17 and located between the axial end of the motor housing 1 and the volute 9.

[0048] The cooling air supply at the intake end of the main shaft 17 comes from the gas leaking into the motor housing 1 from behind the impeller 16;

[0049] The motor housing 1 is also provided with a motor cooling channel 22, which is connected to the first cavity 13. Liquid coolant can enter the motor cooling channel 22 and cool the motor housing 1. After absorbing heat and vaporizing, the liquid coolant enters the first cavity 13.

[0050] The cooling air supply to the return end of the spindle 17 comes from the gas input into the first cavity 13 from the motor cooling channel 22, and from the air inlet end of the spindle 17.

[0051] The air-floating centrifugal refrigerant compressor provided in this application adopts a single-stage compressor form, which reduces the number of parts, improves the operating efficiency of the compressor, reduces the cost of the compressor, and achieves a better cost performance. Since the main shaft 17 only has one end for air intake, in order to ensure that the air-floating radial bearings and air-floating thrust bearings at both ends of the main shaft 17 are supplied with air and cooled, this application uses the gas leaked behind the impeller 16 to supply air and cool the first air-floating radial bearing 4 and the air-floating thrust bearing at the air supply end. Then, liquid coolant is introduced through the motor cooling channel 22 on the motor housing 1, which on the one hand realizes heat dissipation of the motor housing 1, and on the other hand provides cooling gas to the first cavity 13. The cooling gas flowing out from the first air-floating radial bearing 4 and the air-floating thrust bearing mixes with the cooling gas in the first cavity 13, and together they cool and supply air to the magnet in the middle section of the main shaft 17 and the second air-floating radial bearing 5 at the return end. This air supply cooling method solves the air supply and heat dissipation problem of the air-floating bearings, and also realizes the balance of axial force of the compressor rotor 3, making the compressor structure simpler and more compact.

[0052] like Figure 1 As shown, in a preferred embodiment, it further includes a bearing housing 6, a back plate seal 7, and a wheel cover seal 8;

[0053] The bearing housing 6 is installed at one end of the motor housing 1. The first air-floating radial bearing 4 is installed in the bearing housing 6, and the second air-floating radial bearing 5 is installed in the bearing housing integrally formed with the other end of the motor housing 1. The main shaft 17 of the compressor rotor 3 passes through the motor stator 2 and is rotatably connected to the motor housing 1 by the support of the first air-floating radial bearing 4 and the second air-floating radial bearing 5.

[0054] In order to control the amount of gas leakage at the impeller back and the impeller cover of the impeller 16, a back plate seal 7 and an impeller cover seal 8 are also provided; the back plate seal 7 is located at the impeller back of the impeller 16 and is mounted on the bearing housing 6 by screws; the impeller cover seal 8 is located at the impeller cover of the impeller 16 and is mounted on the volute 9 by screws.

[0055] In a preferred embodiment, such asFigure 2 As shown, the compressor rotor section 3 also includes a thrust plate 18, a bushing 19, and a lock nut 20;

[0056] The air inlet end of the main shaft 17 passes through the first air-bearing radial bearing 4, the middle section of the main shaft 17 passes through the motor stator 2, and the exhaust end of the main shaft 17 passes through the second air-bearing radial bearing 5.

[0057] The thrust plate 18 is located at the air intake end of the main shaft 17, with one end positioned by the shoulder of the main shaft 17 and the other end pressed by the bushing 19.

[0058] The air-floating thrust bearing is installed between the bearing housing 6 and the back plate seal 7 and is located on both sides of the thrust plate 18 in the axial direction. The clearance of the air-floating thrust bearing is controlled by adjusting the thickness of the thrust adjusting block, so that the air-floating thrust bearing can get enough cooling gas.

[0059] Impeller 16, thrust disk 18, and bushing 19 are all mounted on main shaft 17 through a central hole. One axial end of bushing 19 abuts against the end face of thrust disk 18; the other axial end of bushing 19 abuts against the back of impeller 16; the cover of impeller 16 contacts lock nut 20 and is fixed by the friction generated by the stretching deformation of the tie rod and the locking torque of lock nut 20.

[0060] The backplate seal 7 is fitted onto the bushing 19, and the radial gap between the backplate seal 7 and the bushing 19 forms an airflow channel.

[0061] The leaked gas from the impeller 16 passes through the back plate seal 7 and then reaches the airflow channel formed by the radial gap between the back plate seal 7 and the bushing 19, thereby supplying air to the first air-bearing radial bearing 4.

[0062] In a preferred embodiment, such as Figure 3 As shown, the airflow channel formed by the radial gap between the bushing 19 and the back plate seal 7 is the air intake cooling channel 21. The gas leaking from the back of the impeller 16 flows through the air intake cooling channel 21 to the thrust plate 18, the air-bearing thrust bearing and the first air-bearing radial bearing 4, and then flows to the first cavity 13 in the motor housing 1. In this way, the air supply and cooling of the main shaft 17 air intake end are realized, that is, the air supply to the first air-bearing radial bearing 4 and the air-bearing thrust bearing is provided, and at the same time, the air intake end of the main shaft 17 and the thrust plate 18, the air-bearing thrust bearing and the first air-bearing radial bearing 4 are cooled.

[0063] In a preferred embodiment, such as Figure 3As shown, a cooling liquid inlet 25 is provided on the motor housing 1. The cooling liquid inlet 25 is connected to the spiral motor cooling channel 22. The motor cooling channel 22 is connected to the first cavity 13 inside the motor housing 1. The coolant can enter from the cooling liquid inlet 25 and vaporize when passing through the motor cooling channel 22 and enter the first cavity 13. In this way, when the coolant passes through the motor cooling channel 22, it carries away the heat of the motor housing 1 and cools down the motor housing 1 and the motor stator 2. At the same time, the coolant absorbs heat and vaporizes into the first cavity 13, which also replenishes the first cavity 13 with cooling gas.

[0064] In a preferred embodiment, such as Figure 3 As shown, the radial gap between the motor stator 2 and the compressor rotor 3 forms the main shaft cooling channel 24. The cooling gas passing through the thrust plate 18, the air-bearing thrust bearing and the first air-bearing radial bearing 4 reaches the first cavity 13 and mixes with the cooling gas reaching the first cavity 13 from the motor cooling channel 22. Then, it passes through the main shaft cooling channel 24 to cool the middle section of the main shaft 17 where the magnet is provided.

[0065] The cooling effect of the cooling gas passing through the thrust plate 18, the air-bearing thrust bearing and the first air-bearing radial bearing 4 becomes weaker. At this time, the cooling gas that enters the motor cooling channel 22 from the cooling liquid inlet 25 and then enters the first cavity 13 mixes with it, and the cooling effect of the cooling gas is enhanced again. It can then pass through the main shaft cooling channel 24 to cool the middle section of the main shaft 17 where the magnet is located.

[0066] In a preferred embodiment, such as Figure 3 As shown, the airflow channel formed by the radial gap between the second air-bearing radial bearing 5 and the main shaft 17 is the return air cooling channel 23. Cooling gas flows from the main shaft cooling channel 24 to the return air cooling channel 23, supplies air to the second air-bearing radial bearing 5 and cools it, and then flows to the second cavity 12 formed by the motor housing 1 and the motor end cover 10, and is discharged from the return air outlet 26 provided on the motor end cover 10.

[0067] After cooling gas cools the middle section of the main spindle 17 through the main spindle cooling channel 24, it supplies air to the second air-bearing radial bearing 5 and cools it through the return air cooling channel 23. The cooling gas flows through the gap of the motor housing 1 to the second cavity 12, is discharged from the return air outlet 26, and returns to the cooling system. After being cooled and liquefied by the cooling system, part of it is recirculated to the cooling liquid inlet 25.

[0068] In a preferred embodiment, the air supply to the first air-bearing radial bearing 4, the air-bearing thrust bearing, and the thrust disk 18 is controlled by the pressure difference between the impeller 16 back outlet and the first cavity 13.

[0069] The air supply of the second air-bearing radial bearing 5 is controlled by the pressure difference between the return air outlet 26 on the motor end cover 10 and the first cavity 13; thus, the gas flow rate at the air inlet and return air outlet of the main shaft 17 can be adjusted by the pressure difference control, thereby realizing the adjustment of the air supply and cooling degree of the first air-bearing radial bearing 4, the air-bearing thrust bearing and the thrust plate 18, and the second air-bearing radial bearing 5.

[0070] In a preferred embodiment, an inlet guide vane adjustment mechanism 11 is also included. The inlet guide vane adjustment mechanism 11 is mounted on the volute 9 by screws. The inlet guide vane adjustment mechanism 11 adjusts the inlet guide vane blades, actuator 14 and drive shaft 15. The actuator 14 can drive the drive shaft 15 to open and close the guide vane blades at the inlet of the air-float centrifugal refrigerant compressor, thereby adjusting the intake air volume at the inlet of the air-float centrifugal refrigerant compressor, and thus controlling the flow rate of the leaked gas behind the impeller 16.

[0071] The working process of the cooling system of the air-float centrifugal refrigerant compressor in this application is as follows: Figure 3 As shown: The cooling system includes an air inlet cooling channel 21, a motor cooling channel 22, an air return cooling channel 23, a spindle cooling channel 24, a second cavity 12, a first cavity 13, a coolant inlet 25, and an air return outlet 26.

[0072] The leaked gas behind the impeller 16 reaches the first air-bearing radial bearing 4 through the air intake cooling channel 21, cooling the components at the air intake end of the main shaft 17, such as the first air-bearing radial bearing 4, the thrust plate 18, and the air-bearing thrust bearing. The cooled gas reaches the first cavity 13 and mixes with the gas in the motor cooling channel 22. After passing through the main shaft cooling channel 24, it cools the magnet in the middle section of the main shaft 17. The cooled gas reaches the second cavity 12 through the exhaust hole on the motor housing 1 and the gap between the second air-bearing radial bearing 5.

[0073] The mixed gas in the second cavity 12 returns to the cooling system through the return gas outlet 26. After being liquefied by cooling, part of the coolant is recirculated to the cooling liquid inlet 25 to cool the motor housing 1 and to provide supplemental cooling gas for the first cavity 13.

[0074] The entire cooling system is controlled by the pressure difference between the impeller 16 outlet and the first cavity 13, and between the cooling liquid inlet 25 and the return gas outlet 26.

[0075] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0076] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the word “or” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0077] It should also be noted that in the apparatus, equipment, and methods of this application, the components or steps can be disassembled or recombined. These disassemblies or recombinations should be considered as equivalent solutions of this application.

[0078] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0079] It should be understood that the qualifiers “first,” “second,” “third,” “fourth,” “fifth,” and “sixth” used in the description of the embodiments of this application are only used to more clearly illustrate the technical solutions and are not intended to limit the scope of protection of this application.

[0080] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A centrifugal refrigerant compressor with air flotation, characterized in that, include: Motor housing (1), motor stator (2), compressor rotor (3), first air-bearing radial bearing (4), second air-bearing radial bearing (5), air-bearing thrust bearing, volute (9) and motor end cover (10); The motor stator (2) and the compressor rotor (3) are respectively installed inside the motor housing (1). The remaining space after the motor stator (2) and the compressor rotor (3) are installed in the inner cavity of the motor housing (1) forms a first cavity (13). The volute (9) and the motor end cover (10) are respectively located at both ends of the motor housing (1) in the axial direction. The compressor rotor (3) includes a main shaft (17) and an impeller (16). The main shaft (17) is rotatably connected to the motor housing (1) via the first air-bearing radial bearing (4) and the second air-bearing radial bearing (5). The main shaft (17) includes an air inlet end disposed on one side of the first air-bearing radial bearing (4) and the air-bearing thrust bearing, a middle section disposed with a magnet, and an air return end disposed on one side of the second air-bearing radial bearing (5). The air inlet end of the main shaft (17) extends out of the axial end of the motor housing (1). The impeller (16) is disposed on the air inlet end of the main shaft (17) and located between the end of the motor housing (1) and the volute (9). The cooling air supply at the air inlet end of the main shaft (17) comes from the gas leaking into the motor housing (1) from behind the impeller (16); The motor housing (1) is also provided with a motor cooling channel (22), which is connected to the first cavity (13). Liquid coolant can enter the motor cooling channel (22) and cool the motor housing (1). After absorbing heat and vaporizing, the liquid coolant enters the first cavity (13). The cooling air supply to the return end of the main shaft (17) comes from the gas input into the first cavity (13) from the motor cooling channel (22) and the gas from the inlet end of the main shaft (17); The radial gap between the motor stator (2) and the compressor rotor (3) forms a main shaft cooling channel (24). Cooling gas passing through the thrust plate (18) of the compressor rotor (3), the air-bearing thrust bearing and the first air-bearing radial bearing (4) reaches the first cavity (13) and mixes with the cooling gas reaching the first cavity (13) from the motor cooling channel (22). The mixture then passes through the main shaft cooling channel (24) to cool the middle section of the main shaft (17) where the magnet is located. The airflow channel formed by the radial gap between the second air-bearing radial bearing (5) and the main shaft (17) is the return air end cooling channel (23). Cooling gas flows from the main shaft cooling channel (24) to the return air end cooling channel (23) to supply air and cool the second air-bearing radial bearing (5). The cooling gas of the second air-bearing radial bearing (5) flows to the second cavity (12) formed by the motor housing (1) and the motor end cover (10), and is discharged from the return gas outlet (26) provided on the motor end cover (10).

2. The air-float centrifugal refrigerant compressor according to claim 1, characterized in that, It also includes a bearing housing (6), a back plate seal (7), and a wheel cover seal (8); the bearing housing (6) is installed at one end of the motor housing (1), and the first air-floating radial bearing (4) and the second air-floating radial bearing (5) are respectively installed in the bearing housing (6) and the motor housing (1); The back plate seal (7) is located on the back of the impeller (16) and is mounted on the bearing seat (6) by screws; the wheel cover seal (8) is located on the wheel cover of the impeller (16) and is mounted on the volute (9) by screws.

3. The air-float centrifugal refrigerant compressor according to claim 2, characterized in that, The compressor rotor section (3) also includes a bushing (19) and a lock nut (20); The air inlet of the main shaft (17) is inserted into the first air-bearing radial bearing (4), the middle section of the main shaft (17) is inserted into the motor stator (2), and the exhaust end of the main shaft (17) is inserted into the second air-bearing radial bearing (5). The thrust disk (18) is disposed at the air inlet end of the main shaft (17), and the air-floating thrust bearing is installed between the bearing seat (6) and the back plate seal (7) and is located on both sides of the axial direction of the thrust disk (18). The bushing (19) is sleeved on the main shaft (17), and one axial end of the bushing (19) abuts against the end face of the thrust disc (18); the other axial end of the bushing (19) abuts against the back of the impeller (16); the cover of the impeller (16) contacts the lock nut (20) and is fixed by the friction generated by the stretching deformation of the pull rod and the locking torque of the lock nut (20); The backplate seal (7) is fitted onto the bushing (19), and the radial gap between the backplate seal (7) and the bushing (19) forms an airflow channel.

4. The air-float centrifugal refrigerant compressor according to claim 3, characterized in that, The airflow channel formed by the radial gap between the bushing (19) and the back plate seal (7) is the air inlet cooling channel (21). The gas leaking from behind the impeller (16) flows through the air inlet cooling channel (21) to the thrust plate (18), the air-bearing thrust bearing and the first air-bearing radial bearing (4), and then flows to the first cavity (13) in the motor housing (1).

5. The air-float centrifugal refrigerant compressor according to claim 4, characterized in that, The motor housing (1) is provided with a cooling liquid inlet (25), which is connected to the spiral motor cooling channel (22). The motor cooling channel (22) is connected to the first cavity (13) inside the motor housing (1). Coolant can enter from the cooling liquid inlet (25) and vaporize when passing through the motor cooling channel (22) and enter the first cavity (13).

6. The air-float centrifugal refrigerant compressor according to claim 1, characterized in that, The air supply to the first air-bearing radial bearing (4), the air-bearing thrust bearing and the thrust disk (18) is controlled by the pressure difference between the impeller (16) back outlet and the first cavity (13); The air supply of the second air-bearing radial bearing (5) is controlled by the pressure difference between the return air outlet (26) on the motor end cover (10) and the first cavity (13).

7. The air-float centrifugal refrigerant compressor according to claim 1, characterized in that, It also includes an inlet guide vane adjustment mechanism (11), which is mounted on the volute (9) by screws. The inlet guide vane adjustment mechanism (11) includes an actuator (14) and a drive shaft (15). The actuator (14) can drive the drive shaft (15) to open and close the guide vane blades at the air inlet of the air-floating centrifugal refrigerant compressor and adjust the gas flow.

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