Centrifugal compressor

Abstract

The invention relates to the technical field of compressors, and provides a centrifugal compressor which comprises a shell, a motor stator, a rotor, a first air inlet, a first air outlet, a second air inlet and a second air outlet, the motor stator is fixedly arranged in the shell, and the rotor comprises a rotating shaft, a first impeller and a second impeller, the rotating shaft is rotatably arranged in the shell, at least part of the rotating shaft penetrates through the motor stator, the first air inlet and the first air outlet are both communicated with the first impeller, the first impeller is used for compressing air flowing in from the first air inlet and discharging the compressed air through the first air outlet, and the second air inlet and the second air outlet are both communicated with the second impeller; the second impeller is used for compressing gas flowing in from the second gas inlet and discharging the gas through the second gas outlet. According to the scheme, the problems that in a centrifugal compressor in the prior art, a two-stage compressor is not suitable for the low-pressure-ratio working condition, and a single-stage compressor is suitable for the low-pressure-ratio working condition but not suitable for the working condition with the high-capacity refrigeration requirement can be solved.

Description

Technical Field

[0001] The present application relates to the technical field of compressors, and in particular to a centrifugal compressor. Background Art

[0002] With the rapid development of the refrigeration and air-conditioning industry, the application of refrigerant compressors is becoming more and more extensive. The refrigerant compressors in the prior art usually adopt oil-free centrifugal refrigerant compressors, which use air suspension bearings that do not require oil lubrication to prevent oil lubrication from contaminating the refrigerant. Existing oil-free centrifugal refrigerant compressors are divided into two-stage compressors and single-stage compressors.

[0003] For some refrigeration system usage scenarios with a low condensing and evaporating pressure difference (i.e., low pressure ratio conditions), if a two-stage compressor is used, under low pressure ratio operating conditions, the energy loss inside the two-stage compressor will increase, and the flow resistance will also increase, resulting in lower efficiency of the two-stage compressor. In other words, the two-stage compressor is not suitable for low pressure ratio conditions; single-stage compressors are suitable for low pressure ratio conditions, but when dealing with large-capacity refrigeration needs, due to the increase in refrigerant flow, it is difficult to meet the needs of efficient compression under high-speed operating conditions. If a lower speed is used, it may cause other problems to the stability and reliability of the air suspension bearing. In other words, single-stage compressors are not suitable for conditions with large-capacity refrigeration needs. Summary of the invention

[0004] In view of this, the present application provides a centrifugal compressor to solve the problem that in the centrifugal compressor of the prior art, the two-stage compressor is not suitable for low pressure ratio conditions, the single-stage compressor is suitable for low pressure ratio conditions, but under low pressure ratio conditions, the single-stage compressor is not suitable for handling conditions with large capacity refrigeration requirements.

[0005] In order to achieve the above objectives, this application provides the following technical solutions:

[0006] A centrifugal compressor, comprising:

[0007] case;

[0008] A motor stator is fixedly arranged in the housing;

[0009] A rotor, comprising a rotating shaft, a first impeller and a second impeller respectively disposed at two ends of the rotating shaft, wherein the rotating shaft is rotatably disposed on the housing and at least partially penetrates the motor stator;

[0010] A first air inlet and a first air outlet are both connected to the first impeller, and the first impeller is used to compress the gas flowing in from the first air inlet and discharge it through the first air outlet;

[0011] The second air inlet and the second air outlet are both connected to the second impeller, and the second impeller is used for compressing the gas flowing in from the second air inlet and discharging it through the second air outlet.

[0012] Optionally, the rotating shaft is rotatably disposed on the housing via a first air-floating radial bearing and a second air-floating radial bearing;

[0013] The centrifugal compressor has a first cooling channel and a second cooling channel, and the gas leaked from the wheel back of the first impeller can flow to the first air flow channel between the first air-floating radial bearing and the rotating shaft through the first cooling channel, and the gas leaked from the wheel back of the second impeller can flow to the second air flow channel between the second air-floating radial bearing and the rotating shaft through the second cooling channel;

[0014] The shell is provided with a cooling return air outlet, and the first air flow channel and the second air flow channel are both communicated with the cooling return air outlet.

[0015] Optionally, the rotating shaft includes a first impeller shaft, an intermediate shaft, and a second impeller shaft sequentially distributed along the axial direction, the first impeller and the second impeller are respectively arranged on the first impeller shaft and the second impeller shaft, one end of the shell is fixedly provided with a bearing seat, one end of the intermediate shaft is rotatably arranged on the bearing seat through the first air-floating radial bearing, and the other end is rotatably arranged on the shell through the second air-floating radial bearing;

[0016] The centrifugal compressor also includes a first back plate seal and a second back plate seal. The first back plate seal is arranged between the bearing seat and the back of the first impeller, and can guide the gas leaked from the back of the first impeller into the first cooling channel. The second back plate is arranged between the casing and the back of the second impeller, and can guide the gas leaked from the back of the second impeller into the second cooling channel.

[0017] Optionally, the centrifugal compressor further includes a thrust adjustment block, which is axially positioned between the bearing seat and the first back plate seal, and the rotor further includes a thrust plate and a bushing which are axially distributed and sleeved outside the first impeller shaft, and a portion of the thrust plate extends between the bearing seat and the first back plate seal, and a thrust bearing is provided between the thrust plate and the first back plate seal and between the thrust plate and the bearing seat along the axial direction of the rotating shaft, wherein:

[0018] In the radial direction of the rotating shaft, there is a first gap between the first back plate seal and the bushing, in the axial direction of the rotating shaft, there is a second gap between the first back plate seal and the thrust bearing adjacent thereto, and / or, there is a second gap between the first side surface of the thrust plate and the thrust bearing adjacent thereto, in the radial direction of the rotating shaft, there is a third gap between the thrust plate and the thrust adjustment block, in the axial direction of the rotating shaft, there is a fourth gap between the bearing seat and the thrust bearing adjacent thereto, and / or, there is a fourth gap between the second side surface of the thrust plate and the thrust bearing adjacent thereto, and in the radial direction of the rotating shaft, there is a fifth gap between the intermediate shaft and the bearing seat;

[0019] The first cooling channel includes the first gap, the second gap, the third gap, the fourth gap, and the fifth gap which are connected in sequence, and the fifth gap is connected to the first air flow channel.

[0020] Optionally, the second back plate sealing sleeve is arranged outside the intermediate shaft, and has a sixth gap with the intermediate shaft in the radial direction and a seventh gap with the intermediate shaft in the axial direction, and the second cooling channel includes the sixth gap and the seventh gap that are connected, and the seventh gap is connected to the second air flow channel.

[0021] Optionally, the shell is provided with a cooling liquid inlet interface and a third circulation groove, the cooling liquid inlet interface is used to connect external coolant, the slot of the third circulation groove faces the motor stator, and forms a stator cooling channel with the motor stator, and the stator cooling channel is connected to the cooling return air outlet.

[0022] Optionally, the shell, the motor stator, the intermediate shaft, and the bearing seat form a first cavity, a first air flow channel between the first air-floating radial bearing and the rotating shaft is communicated with the first cavity, a portion of the shell away from the bearing seat, the intermediate shaft, and the motor stator form a second cavity, and a second air flow channel between the second air-floating radial bearing and the rotating shaft is communicated with the second cavity;

[0023] The first cavity and the second cavity are in communication with the cooling return air outlet.

[0024] Optionally, there is a gap between the motor stator and the rotating shaft to form a rotating shaft cooling channel, the stator cooling channel is connected to the second cavity, the second cavity is connected to the rotating shaft cooling channel, the rotating shaft cooling channel is connected to the first cavity, and the first cavity is connected to the cooling return air outlet.

[0025] Optionally, along the axial direction of the rotating shaft, both ends of the shell are open ends, and the centrifugal compressor further includes:

[0026] A first volute and a first air inlet seat, wherein the first volute is sealedly connected to one of the opening ends, the first impeller extends into the first volute through the corresponding opening end, the first air inlet seat is connected to the first volute, and the outlet of the first air inlet seat is aligned and communicated with the suction port of the first impeller, the inlet of the first air inlet seat forms the first air inlet, and the outlet of the first volute forms the first exhaust port;

[0027] A second volute and a second air inlet seat, the second volute is sealed and connected to the other open end, the second impeller extends into the second volute through the corresponding open end, the second air inlet seat is connected to the second volute, and the outlet of the second air inlet seat is aligned and connected with the suction port of the second impeller, the inlet of the second air inlet seat forms the second air inlet, and the outlet of the second volute forms the second exhaust port.

[0028] Optionally, at least a portion of the rotating shaft is a hollow structure.

[0029] In the centrifugal compressor provided in the embodiment of the present application, a set of motor stators and rotors are used to drive the first impeller and the second impeller to rotate simultaneously, so that air is sucked in at both ends of the centrifugal compressor at the same time. The first impeller and the second impeller located at both ends of the centrifugal compressor simultaneously compress the gas and then discharge it, so that the centrifugal compressor in the embodiment of the present application achieves single-stage compression and double-suction and double-discharge effects, meeting the high speed, large capacity and high efficiency use requirements of the centrifugal compressor.

[0030] Compared with the two-stage compressor in the prior art, the centrifugal compressor in the embodiment of the present application is a single-stage compression, which is suitable for low-pressure ratio conditions and can meet the high-efficiency use requirements under low-pressure ratio conditions. Compared with the single-stage compressor in the prior art, the embodiment of the present application has the function of double suction and double discharge, and therefore, it is not only suitable for low-pressure ratio conditions, but also suitable for processing conditions with large-capacity refrigeration requirements. It can be seen that the centrifugal compressor provided by the embodiment of the present application can solve the problem that in the centrifugal compressor of the prior art, the two-stage compressor is not suitable for low-pressure ratio conditions, and the single-stage compressor is suitable for low-pressure ratio conditions, but is not suitable for processing conditions with large-capacity refrigeration requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0032] Figure 1 A schematic diagram of the structure of a centrifugal compressor provided in an embodiment of the present application;

[0033] Figure 2 A schematic diagram of the structure of a rotor provided in an embodiment of the present application;

[0034] Figure 3 A cooling path diagram of a centrifugal compressor provided in an embodiment of the present application;

[0035] Figure 4 A positional relationship diagram of the first air inlet, the first exhaust port, the second air inlet, and the second exhaust port of the centrifugal compressor provided in an embodiment of the present application.

[0036] exist Figure 1-Figure 4 middle:

[0037] 1. Shell;

[0038] 2. Motor stator;

[0039] 3. rotor; 31. first impeller; 32. second impeller; 33. rotating shaft; 331. first impeller shaft; 332. second impeller shaft; 333. intermediate shaft; 34. thrust plate; 35. bushing; 36. first lock nut; 37. second lock nut;

[0040] 4. The first air-floating radial bearing;

[0041] 5. Second air-floating radial bearing;

[0042] 6. Bearing seat;

[0043] 7. First back plate sealing;

[0044] 8. Second back plate sealing;

[0045] 9. First round cover seal;

[0046] 10. First volute;

[0047] 11. Second volute;

[0048] 12. First air intake seat;

[0049] 13. Second air intake seat;

[0050] 14. First cavity;

[0051] 15. Second cavity;

[0052] 16. Thrust adjustment block;

[0053] 17. Second wheel cover seal;

[0054] 21. A first cooling channel;

[0055] 22. Stator cooling channel;

[0056] 23. Second cooling channel;

[0057] 24. Rotating shaft cooling channel;

[0058] 25. Cooling liquid inlet interface;

[0059] 26. Cooling return air outlet;

[0060] 27. First air inlet;

[0061] 28. Second air inlet;

[0062] 29. The first exhaust port;

[0063] 30. Second exhaust port. DETAILED DESCRIPTION

[0064] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0065] like Figure 1-Figure 4 As shown, the embodiment of the present application provides a centrifugal compressor, which can be used to compress refrigerant. The centrifugal compressor includes a housing 1, a motor stator 2, a rotor 3, a first air inlet 27 and a first air outlet 29, a second air inlet 28 and a second air outlet 30.

[0066] Among them, the motor stator 2 is fixed in the shell 1. Optionally, the motor stator 2 can be hot-installed in the shell 1. The lead wires of the motor stator 2 can be led out to the junction box through the opening on the shell 1 and connected to the sealed terminal board.

[0067] At least part of the rotor 3 is located in the housing 1. The rotor 3 includes a rotating shaft 33, a first impeller 31 and a second impeller 32. The first impeller 31 and the second impeller 32 are respectively fixed at two ends of the rotating shaft 33. The rotating shaft 33 is rotatably arranged on the housing 1. The rotation of the rotating shaft 33 can drive the first impeller 31 and the second impeller 32 to rotate. At least part of the rotating shaft 33 is penetrated in the motor stator 2 so that the rotating shaft 33 can rotate after the motor stator 2 is energized. The rotating shaft 33 can be concentrically arranged with the motor stator 2.

[0068] The first air inlet 27 and the first exhaust port 29 are both connected to a first impeller 31, and the first impeller 31 is used to compress the gas flowing in from the first air inlet 27 and discharge it through the first exhaust port 29. The second air inlet 28 and the second exhaust port 30 are both connected to a second impeller 32, and the second impeller 32 is used to compress the gas flowing in from the second air inlet 28 and discharge it through the second exhaust port 30.

[0069] The first air inlet 27, the first impeller 31, and the first exhaust port 29 constitute a compression stage, and the second air inlet 28, the second impeller 32, and the second exhaust port 30 constitute a compression stage. The two compression stages can be arranged symmetrically to form a double-suction and double-row structural arrangement. The double-suction and double-row structural arrangement meets the high speed, large capacity, and high efficiency requirements of the centrifugal compressor.

[0070] In the centrifugal compressor provided in the embodiment of the present application, a group of motor stators 2 and rotors 3 are used to drive the first impeller 31 and the second impeller 32 to rotate simultaneously, so that air is sucked in at both ends of the centrifugal compressor at the same time. The first impeller 31 and the second impeller 32 located at both ends of the centrifugal compressor simultaneously compress the gas and then discharge it, so that the centrifugal compressor in the embodiment of the present application achieves single-stage compression and double-suction and double-discharge effects, meeting the high speed, large capacity and high efficiency use requirements of the centrifugal compressor.

[0071] Compared with the two-stage compressor in the prior art, the centrifugal compressor in the embodiment of the present application is a single-stage compression, which is suitable for low-pressure ratio conditions and can meet the high-efficiency use requirements under low-pressure ratio conditions. Compared with the single-stage compressor in the prior art, the embodiment of the present application has the function of double suction and double discharge, and therefore, it is not only suitable for low-pressure ratio conditions, but also suitable for processing conditions with large-capacity refrigeration requirements. It can be seen that the centrifugal compressor provided by the embodiment of the present application can solve the problem that in the centrifugal compressor of the prior art, the two-stage compressor is not suitable for low-pressure ratio conditions, and the single-stage compressor is suitable for low-pressure ratio conditions, but is not suitable for processing conditions with large-capacity refrigeration requirements.

[0072] The rotating shaft 33 can be rotatably arranged on the housing 1 through the first air-floating radial bearing 4 and the second air-floating radial bearing 5, and the first air-floating radial bearing 4 and the second air-floating radial sleeve are arranged outside the rotating shaft 33. The first air-floating radial bearing 4 and the second air-floating radial bearing 5 are oil-free bearings, which have the characteristics of high speed, oil-free, high efficiency, low noise, and micro-vibration. When used in the centrifugal compressor for compressing refrigerant in the embodiment of the present application, it can prevent the contamination of the refrigerant by the lubricating oil when using bearings that require oil lubrication, thereby ensuring the efficiency and stability of the centrifugal compressor.

[0073] In a stationary state, the rotating shaft 33 is in contact with the first air-floating radial bearing 4 and the second air-floating radial bearing 5, so that the first air-floating radial bearing 4 and the second air-floating radial bearing 5 support the rotating shaft 33; when the rotating shaft 33 rotates, a first air flow channel is formed between the first air-floating radial bearing 4 and the rotating shaft 33, and a second air flow channel is formed between the second air-floating radial bearing and the rotating shaft 33.

[0074] Since the first air-floating radial bearing 4 and the second air-floating radial bearing 5 both use gas as lubricant, in some optional embodiments, a dedicated air supply system may be installed to supply air to the first air-floating radial bearing 4 and the second air-floating radial bearing 5 .

[0075] When the impeller rotates, since the working surface of the impeller is in the high-pressure area and the wheel back is in the low-pressure area, the pressure difference will drive the high-pressure gas to flow to the low-pressure area, causing gas leakage on the wheel back of the impeller. Therefore, in another optional embodiment, the centrifugal compressor can have a first cooling channel 21 and a second cooling channel 23, and the gas leaked from the wheel back of the first impeller 31 can flow to the first air flow channel through the first cooling channel 21 to cool the first air-floating radial bearing 4, and the gas leaked from the wheel back of the second impeller 32 can flow to the second air flow channel through the second cooling channel 23 to cool the second air-floating radial bearing 5.

[0076] In this case, the centrifugal compressor in the embodiment of the present application does not require an additional bearing air supply system. The application of the centrifugal compressor can simplify the system design and achieve maintenance-free product.

[0077] Of course, in order to avoid a large amount of gas accumulation inside the shell 1, the shell 1 can also be provided with a cooling return air outlet 26, and the first air flow channel and the second air flow channel can be connected to the cooling return air outlet 26, so that the gas after cooling the first air-floating radial bearing 4 and the second air-floating radial bearing 5 can be discharged outside the shell 1 through the cooling return air outlet 26.

[0078] The rotating shaft 33 may include a first impeller shaft 331, an intermediate shaft 333 and a second impeller shaft 332 distributed in sequence along the axial direction. The first impeller 31 and the second impeller 32 can be fixed on the first impeller shaft 331 and the second impeller shaft 332 respectively. The intermediate shaft 333 passes through the motor stator 2. A bearing seat 6 can be fixed on one end of the shell 1. One end of the intermediate shaft 333 can be rotatably disposed on the bearing seat 6 through a first air-floating radial bearing 4, and the other end can be rotatably disposed on the shell 1 through a second air-floating radial bearing 5.

[0079] In this case, the intermediate shaft 333 passes through the motor stator 2. After the motor stator 2 is energized, it can drive the intermediate shaft 333 to drive the entire rotor 3 to rotate, and the intermediate shaft 333 is supported by the first air-floating radial bearing 4 and the second air-floating radial bearing 5, so that the entire rotor 3 is supported by the first air-floating radial bearing 4 and the second air-floating radial bearing 5.

[0080] The centrifugal compressor also includes a first backplate seal 7 and a second backplate seal 8. The first backplate seal 7 is arranged between the bearing seat 6 and the back of the first impeller 31, and can be installed on the bearing seat 6 by screws, and is used to seal the gap between the back of the first impeller 31 and the first volute 10 (see below) so that the gas compressed by the first impeller 31 can enter the first volute 10. The first backplate seal 7 can also guide the gas leaked from the back of the first impeller 31 into the first cooling channel 21; the second backplate seal 8 is arranged between the casing 1 and the back of the second impeller 32, and can be installed on the casing 1 by screws, and is used to seal the gap between the back of the second impeller 32 and the second volute 11 (see below) so that the gas compressed by the second impeller 32 can enter the second volute 11. The second backplate seal 8 can also guide the gas leaked from the back of the second impeller 32 into the second cooling channel 23.

[0081] The backplate seal installed behind the impeller can not only prevent gas leakage, but also guide the gas leaking from the back of the wheel to ensure that the gas leaking from the back of the wheel can be safely discharged through a predetermined path. For example, the backplate seal design includes exhaust ports, pressure relief holes or other guiding structures to guide the leaking gas to a safe area.

[0082] In the embodiment of the present application, the exhaust port, pressure relief hole or other air outlet port of the first back plate seal 7 can be designed on the surface of the first back plate seal 7 facing the first cooling channel 21 (for example, the surface of the first back plate seal 7 facing the bushing 35 below, so that the exhaust port, pressure relief hole or other air outlet port of the guide structure is connected to the first gap), so as to be connected to the first cooling channel 21, thereby enabling the first back plate seal 7 to guide the gas leaked from the back of the first impeller 31 into the first cooling channel 21.

[0083] Similarly, the exhaust port, pressure relief hole or other air outlet port of the second back plate seal 8 can be designed on the surface of the second back plate seal 8 facing the second cooling channel 23 (for example, the surface of the first back plate seal 7 facing the intermediate shaft 333 below, so that the exhaust port, pressure relief hole or other air outlet port of the guide structure is connected to the sixth gap), so as to be connected to the second cooling channel 23, thereby enabling the second back plate seal 8 to guide the gas leaked from the back of the second impeller 32 into the second cooling channel 23.

[0084] In this case, the first back plate seal 7 and the second back plate seal 8 can not only guide the gas leaked from the back of the first impeller 31 and the back of the second impeller 32 to the first air-floating radial bearing 4 and the second air-floating radial bearing 5 respectively, but also because the first back plate seal 7 and the second back plate seal 8 can seal the gas leaked from the back of the first impeller 31 and the back of the second impeller 32, they can also control the air supply to the first air-floating radial bearing 4 and the second air-floating radial bearing 5, and prevent a large amount of gas from leaking into the interior of the casing 1 through the back of the impeller.

[0085] The centrifugal compressor may further include a thrust bearing and a thrust adjustment block 16. The thrust bearing and the thrust plate 34 are installed between the bearing seat 6 and the first back plate seal 7. The thrust bearings are distributed on both sides of the thrust plate 34 and are installed and positioned by pins on the circumference. The gap of the thrust bearing is controlled by the thickness of the thrust adjustment block 16 so that the thrust bearing can obtain sufficient cooling gas. Optionally, the thrust bearing may be a gas-lubricated thrust bearing that is lubricated by gas.

[0086] Specifically, the thrust adjustment block 16 is axially positioned (along the axial direction of the rotating shaft 33) between the bearing seat 6 and the first back plate seal 7, and can be installed on the bearing seat 6 and the first back plate seal 7 by connecting parts such as screws or pins. The rotor 3 also includes a thrust plate 34 and a bushing 35 that are axially distributed and sleeved outside the first impeller shaft 331. Part of the thrust plate 34 extends between the bearing seat 6 and the first back plate seal 7. The thrust adjustment block 16 can be an annular structure and is sleeved on the outer periphery of the thrust plate 34. Along the axial direction of the rotating shaft 33, thrust bearings are provided between the thrust plate 34 and the first back plate seal 7, and between the thrust plate 34 and the bearing seat 6. The thickness of the thrust adjustment block 16 is used to control the gap between one of the thrust bearings and the first back plate seal 7 and the gap between the other thrust bearing and the bearing seat 6.

[0087] In the radial direction of the rotating shaft 33, there is a first gap between the first back plate seal 7 and the bushing 35, in the axial direction of the rotating shaft 33, there is a second gap between the first back plate seal 7 and the thrust bearing adjacent thereto, and / or, there is a second gap between the first side surface of the thrust plate 34 (the side surface close to the first back plate seal 7) and the thrust bearing adjacent thereto, in the radial direction of the rotating shaft 33, there is a third gap between the thrust plate 34 and the thrust adjustment block 16, in the axial direction of the rotating shaft 33, there is a fourth gap between the bearing seat 6 and the thrust bearing adjacent thereto, and / or, there is a fourth gap between the second side surface of the thrust plate 34 (the side surface close to the bearing seat 6) and the thrust bearing adjacent thereto, and in the radial direction of the rotating shaft 33, there is a fifth gap between the intermediate shaft 333 and the bearing seat 6;

[0088] The first cooling channel 21 includes a first gap, a second gap, a third gap, a fourth gap and a fifth gap which are connected in sequence, and the fifth gap is connected to the first air flow channel.

[0089] After the bushing 35 and the first back plate seal 7 are installed, a first gap is formed for gas circulation, which reduces the wheel back leakage of the first impeller 31 on the one hand, and supplies air to the thrust bearing and the first air-floating radial bearing 4 on the other hand.

[0090] In this case, full utilization is made of the gap between the rotating parts (such as the rotor 3) and the non-rotating parts (such as the first back plate seal 7 and the bearing seat 6) during the operation of the centrifugal compressor in the embodiment of the present application to form the first cooling channel 21, so that the gap between the rotating parts and the non-rotating parts can not only ensure the smooth rotation of the rotating parts, but also form the first cooling channel 21, achieving the effect of serving two purposes in one and simplifying the structure of the centrifugal compressor.

[0091] The second back plate seal 8 is sleeved outside the intermediate shaft 333 and has a sixth gap with the intermediate shaft 333 in the radial direction and a seventh gap with the intermediate shaft 333 in the axial direction. The second cooling channel 23 includes the sixth gap and the seventh gap, and the seventh gap is connected to the second air flow channel.

[0092] The sixth gap for gas circulation formed after the intermediate shaft 333 and the second back plate seal 8 are installed reduces the wheel back leakage of the second impeller 32 on the one hand, and supplies air to the second air-floating radial bearing 5 on the other hand.

[0093] In this case, full utilization is made of the gap between the rotating parts (such as the rotor 3) and the non-rotating parts (such as the second back plate seal 8) during the operation of the centrifugal compressor in the embodiment of the present application to form the second cooling channel 23, so that the gap between the rotating parts and the non-rotating parts can not only ensure the smooth rotation of the rotating parts, but also form the second cooling channel 23, achieving the effect of serving two purposes in one and simplifying the structure of the centrifugal compressor.

[0094] In order to ensure the position stability of the first impeller 31 and the second impeller 32 after being installed on the rotating shaft 33, in the embodiment of the present application, the rotor 3 may also include a first lock nut 36 and a second lock nut 37, and the first impeller 31 and the second impeller 32 are axially positioned by the first lock nut 36 and the second lock nut 37. The first impeller 31, the second impeller 32, the thrust plate 34, and the bushing 35 are installed on the rotating shaft 33 through the center hole, and the end faces of the first impeller 31, the second impeller 32, the thrust plate 34, the bushing 35, the first lock nut 36, and the second lock nut 37 are perpendicular to the axis (axis) of the rotating shaft 33, and the inner hole is concentric with the axis.

[0095] Specifically, the thrust plate 34 is mounted on the first impeller shaft 331 and positioned by a shaft shoulder (formed by the different diameters of the first impeller shaft 331 and the intermediate shaft 333). The bushing 35 is mounted on the side of the thrust plate 34 facing away from the intermediate shaft 333. The two sides of the thrust plate 34 are in contact with the end face of the intermediate shaft 333 and the bushing 35 respectively (that is, one end of the thrust plate 34 is positioned by the shaft shoulder of the rotating shaft 33, and the other end is pressed by the bushing 35). The rear end face of the first impeller 31 is in contact with the bushing 35, and the front end face is in contact with the first impeller 31. The first lock nut 36 contacts the first impeller 31 axially through the thread on the first impeller shaft 331, and is fixed by the friction force generated by the locking torque; the rear end face of the second impeller 32 is positioned by the shaft end (formed by the different diameters of the second impeller shaft 332 and the intermediate shaft 333), and the front end face of the second impeller 32 contacts the second lock nut 37, and the second lock nut 37 locks the second impeller 32 axially through the thread on the second impeller shaft 332, and is fixed by the friction force generated by the locking torque.

[0096] In the embodiment of the present application, the rotating shaft 33 includes a first impeller shaft 331, a magnet, a magnetic steel sleeve, a second impeller shaft 332, and a magnetic steel baffle. The magnet and the magnetic steel sleeve are coaxially arranged. After the magnetic steel baffle is installed with the first impeller shaft 331 and the second impeller shaft 332, they are respectively mounted on both ends of the magnetic steel sleeve.

[0097] During the operation of the centrifugal compressor, the motor stator 2 will generate heat. In order to cool the motor stator 2, in the embodiment of the present application, the shell 1 may be provided with a cooling liquid inlet interface 25 and a third circulation groove. The cooling liquid inlet interface 25 is used to connect external cooling liquid. The slot of the third circulation groove faces the motor stator 2 and forms a stator cooling channel 22 with the motor stator 2. The stator cooling channel 22 is connected to the cooling return air outlet 26.

[0098] The coolant entering from the cooling liquid inlet interface 25 flows through the stator cooling channel 22 to undergo phase change to cool the motor stator 2, thereby preventing the motor stator 2 from overheating and affecting the normal operation of the centrifugal compressor. The gas after the phase change of the coolant can be discharged through the cooling return air outlet 26.

[0099] In the above, the first air flow passage and the second air flow passage are communicated with the cooling return air outlet 26 .

[0100] In an optional embodiment, the first air flow channel and the second air flow channel may be connected to the cooling return air outlet 26 through a connecting pipe.

[0101] In another optional embodiment, the shell 1, the motor stator 2, the intermediate shaft 333, and the bearing seat 6 form a first cavity 14, and the first air flow channel between the first air-floating radial bearing 4 and the rotating shaft 33 is connected to the first cavity 14. The part of the shell 1 away from the bearing seat 6, the intermediate shaft 333, and the motor stator 2 form a second cavity 15, and the second air flow channel between the second air-floating radial bearing 5 and the rotating shaft 33 is connected to the second cavity 15. The first cavity 14 and the second cavity 15 are connected to the cooling return air outlet 26, so that the first air flow channel and the second air flow channel are connected to the cooling return air outlet 26.

[0102] In this case, the remaining internal space of the housing 1 after the rotor 3 and other components are assembled is fully utilized to achieve the communication between the first air flow channel and the second air flow channel and the cooling return air outlet 26, thereby simplifying the structure of the centrifugal compressor.

[0103] During the operation of the centrifugal compressor, the rotating shaft 33 will generate heat when it rotates. In order to cool the rotating shaft 33, in the embodiment of the present application, a gap is provided between the motor stator 2 and the rotating shaft 33 to form a rotating shaft cooling channel 24. The stator cooling channel 22 is connected to the second cavity 15, the second cavity 15 is connected to the rotating shaft cooling channel 24, the rotating shaft cooling channel 24 is connected to the first cavity 14, and the first cavity 14 is connected to the cooling return air outlet 26.

[0104] In this case, during the operation of the centrifugal compressor in the embodiment of the present application, full use is made of the gap between the rotating component, the rotating shaft 33, and the non-rotating component, the motor stator 2, to form a rotating shaft cooling channel 24, so that the gap between the rotating shaft 33 and the motor stator 2 can not only ensure the smooth rotation of the rotating shaft 33, but also form a rotating shaft cooling channel 24, thereby achieving a dual-purpose effect and simplifying the structure of the centrifugal compressor.

[0105] During the operation of the centrifugal compressor, the liquid entering from the cooling liquid inlet interface 25 flows through the stator cooling channel 22 and undergoes a phase change to cool the motor stator 2 , and the gas after the phase change enters the second cavity 15 .

[0106] The leakage gas from the back of the second impeller 32 passes through the second cooling channel 23 to reach the second air-floating radial bearing 5 to cool the second air-floating radial bearing 5. The cooled gas reaches the second cavity 15 and mixes with the gas that enters the second cavity 15 through the stator cooling channel 22. After that, it passes through the rotating shaft cooling channel 24 to cool the magnetic steel part of the rotating shaft 33. The cooled gas reaches the first cavity 14.

[0107] The leaked gas from the wheel back of the first impeller 31 enters the first cooling channel 21 to cool the thrust bearing. The cooled gas reaches the first air-floating radial bearing 4 , and then cools the first air-floating radial bearing 4 . The cooled gas reaches the first cavity 14 .

[0108] The cooling air mixed in the first cavity 14 is discharged to the outside of the housing 1 through the cooling return air outlet 26 and returns to the system.

[0109] It should be noted that the entire cooling system is controlled by the pressure difference between the cooling liquid inlet interface 25 , the first cavity 14 and the second cavity 15 , and the cooling return air outlet 26 .

[0110] Along the axial direction of the rotating shaft 33 , both ends of the casing 1 are open ends. The centrifugal compressor further includes a first volute 10 and a first air inlet seat 12 , a second volute 11 and a second air inlet seat 13 .

[0111] The first volute 10 can be connected to the shell 1 by screws, and the first volute 10 is sealed with one of the opening ends. The first volute 10 is positioned by the end face and the step of the shell 1 to ensure the concentricity of the first volute 10 and the rotor 3. The first impeller 31 extends into the first volute 10 through the corresponding opening end. The first air inlet seat 12 is connected to the first volute 10, and the outlet of the first air inlet seat 12 is aligned and connected with the suction port of the first impeller 31. The inlet of the first air inlet seat 12 forms a first air inlet 27, and the outlet of the first volute 10 forms a first exhaust port 29.

[0112] During the operation of the centrifugal compressor, external air enters the first air intake seat 12 , the suction port of the first impeller 31 , the first impeller 31 , the first volute 10 in sequence through the first air intake port 27 , and is finally discharged through the first exhaust port 29 .

[0113] The second volute 11 can be connected to the shell 1 by screws, and the second volute 11 is sealed with the other open end. The second volute 11 can be positioned by the end face and the step of the shell 1 to ensure the concentricity of the second volute 11 and the rotor 3. The second impeller 32 extends into the second volute 11 through the corresponding open end. The second air inlet seat 13 is connected to the second volute 11, and the outlet of the second air inlet seat 13 is aligned and connected with the suction port of the second impeller 32. The inlet of the second air inlet seat 13 forms a second air inlet 28, and the outlet of the second volute 11 forms a second exhaust port 30.

[0114] During the operation of the centrifugal compressor, external air enters the second air intake seat 13 , the suction port of the second impeller 32 , the second impeller 32 , the second volute 11 in sequence through the second air intake port 28 , and is finally discharged through the second air exhaust port 30 .

[0115] Optionally, the first air intake seat 12 can be located in the first volute 10, and the first volute 10 can be provided with a first positioning step. The outer wall of the inlet end of the first air intake seat 12 is provided with a first radial protrusion, and the first radial protrusion abuts against the first positioning step to connect the first air intake seat 12 with the first volute 10. Furthermore, the centrifugal compressor can also be provided with a first end cover, the first end cover has an opening, and the opening is directly connected to the inlet of the first air intake seat 12. The first end cover is fixedly connected to the end of the first volute 10 facing away from the casing 1 by bolts, and the first air intake seat 12 is pressed against the first impeller 31 to prevent the first air intake seat 12 from falling off.

[0116] Optionally, the second air intake seat 13 can be located in the second volute 11, the second volute 11 can be provided with a second positioning step, the outer wall of the inlet end of the second air intake seat 13 is provided with a second radial protrusion, the second radial protrusion abuts against the second positioning step, so that the second air intake seat 13 is connected to the second volute 11. Furthermore, the centrifugal compressor can also be provided with a second end cover, the second end cover has an opening, and the opening is directly connected to the inlet of the first air intake seat 12, the second end cover is fixedly connected to the end of the second volute 11 facing away from the casing 1 by bolts, and the second air intake seat 13 is pressed against the second impeller 32 to prevent the second air intake seat 13 from falling off.

[0117] The centrifugal compressor further comprises a first wheel cover seal 9 and a second wheel cover seal 17 . The first wheel cover seal 9 can be mounted on the first volute 10 by screws, and the second wheel cover seal 17 can be mounted on the second volute 11 by screws.

[0118] In the embodiment of the present application, at least a portion of the rotating shaft 33 may be a hollow structure to provide a lightweight design for the rotor 3, thereby reducing the load on the air-floating radial bearing and improving the stability and reliability of the operation.

[0119] The wheel back seal design in the embodiment of the present application enables the axial force to be effectively controlled, thereby improving the reliability of the compressor.

[0120] The diameters of the first back plate seal 7 and the second back plate seal 8 can be different. For example, the diameter of the first back plate seal 7 can be larger than the diameter of the second back plate seal 8. In this way, the different diameters of the first back plate seal 7 and the second back plate seal 8 can control the axial force within the load-bearing range of the thrust bearing and ensure that there is sufficient string momentum to ensure air supply to the bearing.

[0121] The centrifugal compressor provided in the embodiment of the present application is a double-suction oil-free centrifugal refrigerant compressor using a dynamic pressure gas suspension bearing, which adopts a single-stage double-suction compression form to achieve the function of simultaneous suction and exhaust at both ends. This structure not only simplifies the design of the centrifugal compressor and improves the compression efficiency, but also enables the centrifugal compressor to have a considerable capacity and broaden the application range of the centrifugal compressor. In addition, such a structural design not only reduces maintenance costs, but also provides new solutions for certain special fields of the refrigeration and air-conditioning industry.

[0122] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0123] The block diagrams of the devices, apparatuses, equipment, and systems involved in this application are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagram. As will be appreciated by those skilled in the art, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, referring to "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "and / or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The words "such as" used here refer to the phrase "such as but not limited to", and can be used interchangeably with them.

[0124] It should also be noted that in the apparatus, device and method of the present application, each component or each step can be decomposed and / or recombined. Such decomposition and / or recombination should be regarded as equivalent solutions of the present application.

[0125] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0126] It should be understood that the qualifiers "first", "second", "third", "fourth", "fifth" and "sixth" used in the description of the embodiments of the present application are only used to more clearly explain the technical solutions and cannot be used to limit the scope of protection of the present application.

[0127] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A centrifugal compressor, characterized in that: include: Housing (1); A motor stator (2) is fixedly arranged in the housing (1); A rotor (3) comprising a rotating shaft (33), a first impeller (31) and a second impeller (32) respectively arranged at two ends of the rotating shaft (33); the rotating shaft (33) is rotatably arranged on the housing (1) and at least partially penetrates the motor stator (2); A first air inlet (27) and a first air outlet (29), both of which are in communication with the first impeller (31), and the first impeller (31) is used to compress the gas flowing in from the first air inlet (27) and discharge it through the first air outlet (29); The second air inlet (28) and the second air outlet (30) are both in communication with the second impeller (32), and the second impeller (32) is used to compress the gas flowing in from the second air inlet (28) and discharge it through the second air outlet (30).

2. The centrifugal compressor according to claim 1, characterized in that: The rotating shaft (33) is rotatably arranged on the housing (1) via a first air-floating radial bearing (4) and a second air-floating radial bearing (5); The centrifugal compressor comprises a first cooling channel (21) and a second cooling channel (23); gas leaking from the wheel back of the first impeller (31) can flow through the first cooling channel (21) to the first air flow channel between the first air-floating radial bearing (4) and the rotating shaft (33); and gas leaking from the wheel back of the second impeller (32) can flow through the second cooling channel (23) to the second air flow channel between the second air-floating radial bearing (5) and the rotating shaft (33); The housing (1) is provided with a cooling return air outlet (26), and the first air flow channel and the second air flow channel are both in communication with the cooling return air outlet (26).

3. The centrifugal compressor according to claim 2, characterized in that: The rotating shaft (33) comprises a first impeller shaft (331), an intermediate shaft (333) and a second impeller shaft (332) which are sequentially distributed along the axial direction; the first impeller (31) and the second impeller (32) are respectively arranged on the first impeller shaft (331) and the second impeller shaft (332); a bearing seat (6) is fixedly arranged at one end of the housing (1); one end of the intermediate shaft (333) is rotatably arranged on the bearing seat (6) via the first air-floating radial bearing (4); and the other end is rotatably arranged on the housing (1) via the second air-floating radial bearing (5); The centrifugal compressor further comprises a first back plate seal (7) and a second back plate seal (8), wherein the first back plate seal (7) is arranged between the bearing seat (6) and the wheel back of the first impeller (31), and can guide the gas leaking from the wheel back of the first impeller (31) into the first cooling channel (21), and the second back plate is arranged between the casing (1) and the wheel back of the second impeller (32), and can guide the gas leaking from the wheel back of the second impeller (32) into the second cooling channel (23).

4. The centrifugal compressor according to claim 3, characterized in that: The centrifugal compressor further comprises a thrust adjustment block (16), wherein the thrust adjustment block (16) is axially positioned between the bearing seat (6) and the first back plate seal (7), and the rotor (3) further comprises a thrust plate (34) and a bushing (35) which are axially distributed and sleeved outside the first impeller shaft (331), wherein a portion of the thrust plate (34) extends between the bearing seat (6) and the first back plate seal (7), and thrust bearings are arranged between the thrust plate (34) and the first back plate seal (7) and between the thrust plate (34) and the bearing seat (6) along the axial direction of the rotating shaft (33), wherein: Along the radial direction of the rotating shaft (33), there is a first gap between the first back plate seal (7) and the bushing (35); along the axial direction of the rotating shaft (33), there is a second gap between the first back plate seal (7) and the thrust bearing adjacent thereto; and / or, there is a second gap between the first side surface of the thrust plate (34) and the thrust bearing adjacent thereto; along the radial direction of the rotating shaft (33), there is a third gap between the thrust plate (34) and the thrust adjustment block (16); along the axial direction of the rotating shaft (33), there is a fourth gap between the bearing seat (6) and the thrust bearing adjacent thereto; and / or, there is a fourth gap between the second side surface of the thrust plate (34) and the thrust bearing adjacent thereto; and along the radial direction of the rotating shaft (33), there is a fifth gap between the intermediate shaft (333) and the bearing seat (6); The first cooling channel (21) comprises the first gap, the second gap, the third gap, the fourth gap and the fifth gap which are connected in sequence, and the fifth gap is connected to the first air flow channel.

5. The centrifugal compressor according to claim 4, characterized in that: The second back plate seal (8) is sleeved outside the intermediate shaft (333) and has a sixth gap between the second back plate seal (8) and the intermediate shaft (333) in the radial direction and a seventh gap between the second back plate seal (8) and the intermediate shaft (333) in the axial direction. The second cooling channel (23) includes the sixth gap and the seventh gap which are connected, and the seventh gap is connected to the second air flow channel.

6. The centrifugal compressor according to claim 5, characterized in that: The housing (1) is provided with a cooling liquid inlet interface (25) and a third circulation groove, wherein the cooling liquid inlet interface (25) is used to connect with external cooling liquid, the notch of the third circulation groove faces the motor stator (2) and forms a stator cooling channel (22) with the motor stator (2), and the stator cooling channel (22) is connected with the cooling return air outlet (26).

7. The centrifugal compressor according to claim 6, characterized in that: The housing (1), the motor stator (2), the intermediate shaft (333), and the bearing seat (6) form a first cavity (14); a first air flow channel between the first air-floating radial bearing (4) and the rotating shaft (33) is connected to the first cavity (14); a portion of the housing (1) away from the bearing seat (6), the intermediate shaft (333), and the motor stator (2) form a second cavity (15); a second air flow channel between the second air-floating radial bearing (5) and the rotating shaft (33) is connected to the second cavity (15); The first cavity (14) and the second cavity (15) are in communication with the cooling return air outlet (26).

8. The centrifugal compressor according to claim 7, characterized in that: A gap is provided between the motor stator (2) and the rotating shaft (33) to form a rotating shaft cooling channel (24); the stator cooling channel (22) is communicated with the second cavity (15); the second cavity (15) is communicated with the rotating shaft cooling channel (24); the rotating shaft cooling channel (24) is communicated with the first cavity (14); and the first cavity (14) is communicated with the cooling return air outlet (26).

9. The centrifugal compressor according to claim 1, characterized in that: Along the axial direction of the rotating shaft (33), both ends of the housing (1) are open ends, and the centrifugal compressor further comprises: A first volute (10) and a first air inlet seat (12), wherein the first volute (10) is sealedly connected to one of the opening ends, the first impeller (31) extends into the first volute (10) through the corresponding opening end, the first air inlet seat (12) is connected to the first volute (10), and the outlet of the first air inlet seat (12) is aligned and communicated with the suction port of the first impeller (31), the inlet of the first air inlet seat (12) forms the first air inlet port (27), and the outlet of the first volute (10) forms the first exhaust port (29); A second volute (11) and a second air inlet seat (13), wherein the second volute (11) is sealedly connected to the other of the opening ends, the second impeller (32) extends into the second volute (11) through the corresponding opening end, the second air inlet seat (13) is connected to the second volute (11), and the outlet of the second air inlet seat (13) is aligned and connected to the suction port of the second impeller (32), the inlet of the second air inlet seat (13) forms the second air inlet port (28), and the outlet of the second volute (11) forms the second exhaust port (30).

10. The centrifugal compressor according to claim 1, characterized in that At least a part of the rotating shaft (33) is a hollow structure.

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