Centrifugal compressor and heat pump systems

Abstract

The present application discloses a centrifugal compressor and a heat pump system. The centrifugal compressor includes a motor and a compression part, and the motor includes a motor housing and a motor shaft arranged in the motor housing. The compression part is arranged at the axial end of the motor, and the compression part includes an impeller, a driven shaft and a coupling, the driven shaft is connected to the impeller, and the coupling connects the motor shaft and the driven shaft so that the motor drives the impeller to rotate. The centrifugal compressor of the present application increases the axial distance between the motor and the impeller by adding a driven shaft connected to the impeller, and uses a coupling to coaxially connect the motor shaft and the driven shaft, thereby increasing the heat transfer distance of the airflow heat, thereby reducing the heat transferred to the motor, so that the main bearing of the motor operates within a normal temperature range, so as to improve the reliability of the compressor operation.

Description

Technical Field

[0001] The present application relates to a centrifugal compressor and a heat pump system. Background Art

[0002] A heat pump is an energy-saving device that uses high-level energy to make heat flow from a low-level heat source to a high-level heat source. It not only has the ability to improve energy quality, but also has the advantages of mature technology, safety, reliability and simple implementation. Therefore, it is widely used in the civil field.

[0003] At present, air source heat pump technology with water outlet temperature of 55℃ or below is very mature and occupies a dominant position in the market. This type of heat pump can basically meet the needs of domestic hot water and a small number of industrial hot water in conventional residential and commercial buildings; in the field of industrial applications, the requirements for heating temperature are mostly higher than those for civil use, so traditional civil heat pumps cannot meet the needs of the industrial field. If the upper limit of the heat pump output temperature can be increased, it means that the heating needs of more fields can be met, replacing existing coal-fired, oil-fired and gas-fired boiler equipment, which can not only reduce energy consumption, but also improve energy utilization. High-temperature heat pump technology can provide high-quality heat, and the heating temperature can meet the needs of many industrial application fields, so it has broad application prospects.

[0004] Compared with screw compressors and scroll compressors, centrifugal compressors can provide a gas source with a higher pressure ratio. Its working principle is to increase the speed of the refrigerant gas through the centrifugal force generated by the high-speed rotation of the impeller driven by the motor, and complete the conversion of kinetic energy into pressure energy through the expansion chamber. However, a high-pressure gas source means that the exhaust temperature of the compressor is higher, and the pressure is higher, so the heat received by the bearings used to support the motor shaft will also increase, which will cause the bearing to fail due to excessive temperature protection, causing the motor shaft to bend and deform, damaging the performance of the compressor, and reducing the reliability of the unit operation. Summary of the invention

[0005] The present application provides a centrifugal compressor and heat pump system to improve the above-mentioned problem of protection failure caused by excessively high motor bearing temperature, thereby improving the reliability of compressor operation.

[0006] A first aspect of the present application provides a centrifugal compressor, comprising:

[0007] A motor, comprising a motor housing and a motor shaft disposed in the motor housing; and

[0008] The compression part is arranged at the axial end of the motor, and the compression part includes an impeller, a driven shaft and a coupling. The driven shaft is connected to the impeller, and the coupling connects the motor shaft and the driven shaft so that the motor drives the impeller to rotate.

[0009] In some embodiments, the compression part further includes a heat insulating sleeve sleeved on the outside of the coupling.

[0010] In some embodiments, the compression part also includes a sealing baffle arranged on the side of the impeller close to the motor, the sealing baffle has a connecting hole, the driven shaft passes through the connecting hole and is connected to the motor shaft, and the end of the insulation sleeve is connected to the sealing baffle.

[0011] In some embodiments, both ends of the sealing baffle are connected to the motor housing to cover a cross section of the motor housing.

[0012] In some embodiments, a through hole is provided on the wall of the thermal insulation sleeve, and the through hole is used for cooling fluid to flow in.

[0013] In some embodiments, the thermal sleeve is made of copper.

[0014] In some embodiments, the compression part further includes a sealing baffle, which is arranged on a side of the impeller close to the motor and has a connecting hole, and the driven shaft passes through the connecting hole and is connected to the motor shaft.

[0015] In some embodiments, the motor also includes a bearing support and a main bearing fixedly arranged on the motor housing, and the motor shaft is supported on the bearing support through the main bearing. The compression part also includes a diffuser and an auxiliary bearing. The diffuser is fixedly arranged relative to the motor housing, and the auxiliary bearing is arranged between the driven shaft and the diffuser.

[0016] In some embodiments, the auxiliary bearing comprises an air bearing.

[0017] In some embodiments, the centrifugal compressor includes two compression parts respectively arranged at the axial ends of the motor, the two compression parts include a primary compression part and a secondary compression part, and the gas output by the primary compression part enters the secondary compression part for further pressurization.

[0018] A second aspect of the present application provides a heat pump system, comprising the above-mentioned centrifugal compressor.

[0019] Based on the technical solution provided by the present application, a centrifugal compressor includes a motor and a compression part, and the motor includes a motor housing and a motor shaft arranged in the motor housing. The compression part is arranged at the axial end of the motor, and the compression part includes an impeller, a driven shaft and a coupling, the driven shaft is connected to the impeller, and the coupling connects the motor shaft and the driven shaft so that the motor drives the impeller to rotate. The centrifugal compressor of the present application increases the axial distance between the motor and the impeller by adding a driven shaft connected to the impeller, and uses a coupling to coaxially connect the motor shaft and the driven shaft, so as to increase the heat transfer distance of the airflow heat, thereby reducing the heat transferred to the motor, so that the main bearing of the motor operates within a normal temperature range, so as to improve the reliability of the compressor operation.

[0020] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments of the present application with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0022] Figure 1 This is a schematic cross-sectional structure diagram of a centrifugal compressor according to an embodiment of the present application.

[0023] Figure 2 for Figure 1 Schematic diagram of the enlarged structure of the coupling and insulation sleeve of the middle-stage compression section. DETAILED DESCRIPTION

[0024] 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, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its application or use. 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.

[0025] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the application. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0026] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" may include both "above" and "below". The device may also be positioned in other different ways, and the spatially relative descriptions used here are interpreted accordingly.

[0027] The pressure head that a centrifugal compressor can provide is determined by the speed of the impeller. However, due to the strength of the impeller material and the diameter of the impeller, the speed of the impeller cannot be very high. Therefore, for some high-temperature heat pumps that need to provide a higher pressure ratio gas source, two-stage or multi-stage compression is required to ensure that the centrifugal compressor provides sufficient pressure head. However, after using two-stage compression, the exhaust temperature and pressure of the compressor are higher, so the heat received by the motor bearing increases accordingly. Since the babbitt alloy on the inner surface of the motor bearing may fall off when the temperature is too high, the protection of the motor bearing to the motor shaft will fail. This increases the vibration of the motor shaft when it rotates at high speed, causing the shaft to bend and deform, damaging the performance of the compressor, and reducing the reliability of the unit operation.

[0028] In order to solve the above problems, the inventors of the present application have conducted in-depth research and proposed that the heat transfer distance of the airflow heat can be increased by increasing the distance between the compression part and the motor. This can reduce the heat transferred to the motor, allowing the motor bearings to operate within the normal temperature range, thereby improving the reliability of the compressor operation.

[0029] refer to Figure 1 The embodiment of the present application provides a centrifugal compressor, including a motor 1 and a compression part. The motor 1 includes a motor housing 11 and a motor shaft 15 disposed in the motor housing 11. The compression part is disposed at the axial end of the motor 1. The compression part includes an impeller, a driven shaft and a coupling, the driven shaft is connected to the impeller, and the coupling connects the motor shaft 15 and the driven shaft, so that the motor 1 drives the impeller to rotate.

[0030] like Figure 1 As shown, the motor 1 includes a motor housing 11 , a first bearing support 12 , a first main bearing 13 , a motor stator 14 , a motor shaft 15 , a second main bearing 16 and a second bearing support 17 .

[0031] The motor housing 11 is irregular in shape, specifically, the middle main body is a cylindrical cavity, and the two ends are flared. The motor housing 11 is generally formed by casting, and is mainly used to protect the motor components. A spiral cooling channel is arranged inside the motor housing 11, and the refrigerant used for cooling can enter the compressor from bottom to top, take away the heat of the motor along the cooling channel, and reduce the working temperature of the motor.

[0032] The first bearing support 12 and the second bearing support 17 are rotary parts, which provide support for the first main bearing 13 and the second main bearing 16 respectively.

[0033] The first main bearing 13 and the second main bearing 16 are rotating parts, and the inner surface of the parts is coated with babbitt metal to protect the shaft from rotating stably at high speed. Specifically, the first main bearing 13 and the second main bearing 16 are oil bearings, that is, bearings lubricated with lubricating oil.

[0034] The motor stator 14 is a rotating part, mainly composed of a stator core and a stator winding.

[0035] like Figure 1 As shown, the centrifugal compressor of this embodiment includes two compression parts respectively arranged at both ends of the motor 1. The two compression parts include a primary compression part 2 and a secondary compression part 3. The gas output by the primary compression part enters the secondary compression part for further pressurization. The structures of the primary compression part 2 and the secondary compression part 3 are basically the same. The structure of the primary compression part 2 is mainly used as an example for explanation below, and the differences between the secondary compression part 3 and the primary compression part 2 will also be pointed out.

[0036] The first-stage compressor 2 includes a housing 21, a first-stage volute 22, a first locking nut 23, a first-stage impeller 24, a first auxiliary bearing 25, a first-stage diffuser 26, a first sealing baffle 27, a first driven shaft 28, a coupling 29 and a heat-insulating sleeve 20. The housing 21 and the first-stage volute 22 are irregularly shaped and are generally formed by casting. The first-stage impeller 24 is connected to the first driven shaft 28 through the first locking nut 23, and the first driven shaft 28 is coaxially connected to the motor shaft 15 through the coupling 29, so that the rotation of the motor shaft 15 can simultaneously drive the first-stage impeller 24 to rotate. The gas enters the compressor axially from the inlet of the housing 21, changes to radial direction when flowing through the first-stage impeller 24, and then enters the first-stage diffuser 26, and the gas is discharged from the first-stage volute 22.

[0037] The secondary compressor 3 includes a secondary volute 32, a second locking nut 33, a secondary impeller 34, a second auxiliary bearing 35, a secondary diffuser 36, a second sealing baffle 37 and a second driven shaft 38. The secondary volute 32 is an irregular shape and is generally formed by casting. The primary impeller 24 and the secondary impeller 34 are closed impellers and are the core parts of the centrifugal compressor. Figure 1As shown, the axial ends of the motor shaft 15 are connected to the primary impeller 24 and the secondary impeller 34 through the first driven shaft 28 and the second driven shaft 38 respectively, so that when the motor 1 is running, it can drive the primary impeller 24 and the secondary impeller 34 to rotate at high speed. The primary impeller 24 first works on the compressor inlet airflow to speed it up and increase its pressure. The airflow comes out from the outlet of the primary volute 22, enters the secondary impeller 34 through the pipeline, and then works on the secondary impeller 34 to increase its speed and pressure, becoming a high-pressure airflow that meets the operation of the high-temperature heat pump.

[0038] In some other embodiments not shown in the drawings, the centrifugal compressor may also include only one compression part. The compression part is arranged at one axial end of the motor 1 .

[0039] In the technical solution of the embodiment of the present application, a driven shaft connected to the impeller is added, and the motor shaft 15 and the driven shaft are coaxially connected using a coupling. The axial distance between the motor 1 and the impeller is increased to increase the heat transfer distance of the air flow heat. This can reduce the heat transferred to the motor, so that the main bearing of the motor operates within the normal temperature range, thereby improving the reliability of the compressor operation.

[0040] In order to further reduce the transfer of heat from the compression part to the motor, in some embodiments, the compression part also includes a sealing baffle, which is arranged on the side of the impeller close to the motor 1 and has a connecting hole, and the driven shaft passes through the connecting hole and is connected to the motor shaft 15.

[0041] like Figure 1 As shown, the first compression part 2 includes a first sealing baffle 27. The first sealing baffle 27 is connected to the end of the motor housing 11 and covers the end surface of the motor housing 11. In this way, the first sealing baffle 27 forms an effective heat transfer barrier for the first main bearing 13, greatly reducing the heat of the airflow.

[0042] Similarly, the secondary compression section 3 includes a second sealing baffle 37. The second sealing baffle 37 is connected to the end surface of the other end of the motor housing 22 and covers the end surface of the motor housing 11, so that the second sealing baffle 37 forms an effective heat transfer barrier for the second main bearing 16, greatly reducing the heat of the airflow.

[0043] refer to Figure 1 and Figure 2 In order to further reduce the heating temperature of the main bearing, in some embodiments, the compression part also includes a heat insulation sleeve 20 sleeved on the outside of the coupling 29.

[0044] In some embodiments, the compression part also includes a sealing baffle arranged on the side of the impeller close to the motor 1, the sealing baffle has a connecting hole, the driven shaft passes through the connecting hole and is connected to the motor shaft 15, and the end of the insulation sleeve 20 is connected to the sealing baffle.

[0045] like Figure 1As shown, the axial end of the heat insulating sleeve 20 is fixedly disposed on the first sealing baffle 27, thereby achieving fixation.

[0046] In some embodiments, a through hole is provided on the wall of the heat insulating sleeve 20, and the through hole is used to allow the cooling fluid to flow in. For example, a small hole can be opened on the heat insulating sleeve 20 to facilitate the introduction of refrigerant spray cooling, which can not only take away part of the heat of the airflow, but also reduce the heat generated when the shaft rotates at high speed. Moreover, the entire coupling structure can not only play a role in heat insulation and cooling, but also reduce the vibration effect of the shaft when it rotates at high speed, avoid causing bending deformation of the shaft, and comprehensively improve the overall high temperature resistance and operation reliability of the heat pump system.

[0047] In some embodiments, the heat insulating sleeve 20 is made of copper. Preferably, a heat insulating layer may be provided on the outer side of the heat insulating sleeve 20 .

[0048] Furthermore, a fan may be added on the outside of the heat insulating sleeve 20 to further improve the cooling effect.

[0049] The centrifugal compressor of the embodiment of the present application increases the distance between the impeller and the main bearing by adding a driven shaft and a coupling, which makes the cantilever at both ends of the motor shaft too long, and one end of the driven shaft is also installed with impellers, volutes and other parts, which will aggravate the bending strain of the driven shaft. In order to improve the bending of the driven shaft, in some embodiments, the motor 1 also includes a bearing support and a main bearing fixedly arranged on the motor housing 11, and the motor shaft 15 is supported on the bearing support through the main bearing. The compression part also includes a diffuser and an auxiliary bearing, the diffuser is fixedly arranged relative to the motor housing 11, and the auxiliary bearing is arranged between the driven shaft and the diffuser. The setting of the auxiliary bearing provides a support for the driven shaft, thereby preventing the driven shaft from bending.

[0050] Specifically, Figure 1 As shown, a first auxiliary bearing 25 is arranged between the first driven shaft 28 and the first diffuser 26. A second auxiliary bearing 35 is arranged between the second driven shaft 38 and the second diffuser 36. Compared with the main bearing, which needs to bear a larger load, the load carried by the first auxiliary bearing 25 and the second auxiliary bearing 35 is smaller, so the first auxiliary bearing 25 and the second auxiliary bearing 35 can adopt air bearings or other bearings lubricated by refrigerant. In addition, since the first auxiliary bearing 25 and the second auxiliary bearing 35 are close to the impeller, the use of air bearings or other bearings lubricated by refrigerant can also avoid the failure of the protective function of the bearings at high temperatures.

[0051] In some embodiments, the auxiliary bearing comprises an air bearing.

[0052] The embodiment of the present application adopts the above-mentioned structure of arranging the two-stage compression parts at both ends of the motor shaft respectively, so that the direction of the first-stage air intake is opposite to that of the second-stage air intake, so that the axial force exerted on the first driven shaft 28 is opposite to the axial force exerted on the second driven shaft 38. By offsetting the mutual force of the two axial forces, the overall axial force of the compressor can be reduced, the load on the bearings is reduced, and the vibration noise generated during the operation of the compressor is effectively reduced.

[0053] like Figure 1 As shown, the end surface of the first-stage diffuser 26 close to the first sealing baffle 27 includes a protrusion in contact with the first sealing baffle 27 and an intermediate end surface with a gap B between the first sealing baffle 27. Correspondingly, the end surface of the first auxiliary bearing 25 close to the first sealing baffle 27 is tilted inward. The end surface of the second-stage diffuser 36 close to the second sealing baffle 37 is in contact with the second sealing baffle 37. Correspondingly, the second auxiliary bearing 35 has a convex edge protruding radially outward and stuck on the end surface of the second-stage diffuser 36. Since the structures of the first-stage diffuser 26 and the second-stage diffuser 36 are different, the structure of the first auxiliary bearing 25 is also different from that of the second auxiliary bearing 35. The first auxiliary bearing 25 and the second auxiliary bearing 35 play the role of supporting and preventing the diffuser from jumping left and right.

[0054] An embodiment of the present application also provides a heat pump system, comprising the above-mentioned centrifugal compressor.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application rather than to limit it. Although the present application has been described in detail with reference to the preferred embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present application can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present application, which should be included in the scope of the technical solution for protection in the present application.

Claims

1. A centrifugal compressor, characterized in that: include: A motor (1) comprising a motor housing (11) and a motor shaft (15) arranged in the motor housing (11); and a compression part, arranged at an axial end of the motor (1), and comprising an impeller, a driven shaft, a coupling, a heat-insulating sleeve sleeved on the outside of the coupling, and a sealing baffle arranged on a side of the impeller close to the motor (1), the driven shaft being connected to the impeller, the coupling connecting the motor shaft (15) and the driven shaft so that the motor (1) drives the impeller to rotate, the sealing baffle having a connecting hole, the driven shaft passing through the connecting hole and connected to the motor shaft (15), the end of the heat-insulating sleeve being connected to the sealing baffle, and the two ends of the sealing baffle being connected to the motor housing (11) so as to cover the cross section of the motor housing (11); The motor further comprises a bearing support (12) and a main bearing (13) fixedly arranged on the motor housing (11); the motor shaft (15) is supported on the bearing support (12) via the main bearing (13); the compression section further comprises a diffuser and an auxiliary bearing; the diffuser is fixedly arranged relative to the motor housing (11); and the auxiliary bearing is arranged between the driven shaft and the diffuser.

2. The centrifugal compressor according to claim 1, characterized in that: A through hole is arranged on the wall of the heat insulating sleeve, and the through hole is used for cooling fluid to flow in.

3. The centrifugal compressor according to claim 1, characterized in that: The heat insulating sleeve is made of copper.

4. The centrifugal compressor according to claim 1, characterized in that: The auxiliary bearing comprises an air bearing.

5. The centrifugal compressor according to any one of claims 1 to 4, characterized in that: The centrifugal compressor comprises two compression parts respectively arranged at two axial ends of the motor (1), the two compression parts comprising a primary compression part and a secondary compression part, and the gas output by the primary compression part enters the secondary compression part for further pressurization.

6. A heat pump system, characterized in that: Comprising the centrifugal compressor according to any one of claims 1 to 5.

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