CN111365261A

CN111365261A - Multi-split air conditioning system

Info

Publication number: CN111365261A
Application number: CN201811595299.4A
Authority: CN
Inventors: 刘华; 张治平; 李宏波; 陈玉辉; 钟瑞兴; 叶文腾; 亓静利
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2018-12-25
Filing date: 2018-12-25
Publication date: 2020-07-03

Abstract

The invention provides a multi-split air conditioning system which comprises a centrifugal compressor (100), wherein the centrifugal compressor (100) comprises a rotor, a main shaft (101) of the rotor is provided with a multi-stage impeller, an axial bearing and a radial bearing, and at least one of the axial bearing and the radial bearing is a gas bearing. The multi-stage impeller improves the problem of low compression ratio of a multi-split air conditioning system, and improves the problems of temperature rise and large friction loss of an oil lubrication bearing at high rotor rotation speed by using a gas bearing.

Description

Multi-split air conditioning system

Technical Field

The invention relates to the technical field of heating and ventilation equipment, in particular to a multi-split air conditioning system.

Background

The multi-split air conditioning system is widely applied to various building places such as household central air conditioners, markets, factories, hospitals and the like due to wide refrigerating capacity coverage range. At present, a compressor is generally adopted as a scroll compressor in a multi-split air conditioning system. Scroll compressors are less efficient than centrifugal compressors. If the centrifugal compressor is applied to the multi-split air-conditioning system, the energy efficiency of the multi-split air-conditioning system is obviously improved. The working range of the multi-split air conditioning system is wide and ranges from minus 30 ℃ to 50 ℃. Conventional two-stage refrigeration centrifugal compressors typically have pressure ratios within 5. To apply the centrifugal compressor to the multi-split air conditioning system, the working pressure ratio of the centrifugal compressor needs to reach 10, which is a challenge to the design of the centrifugal compressor. The centrifugal compressor applied to the multi-split air conditioning system has small cooling capacity and high rotating speed, and if a common oil lubrication bearing is adopted, the temperature rise and the friction loss of the bearing are large, so that the running reliability of the compressor is influenced.

Disclosure of Invention

In order to improve the technical defects, the invention provides a multi-split air conditioning system which comprises a centrifugal compressor, wherein the centrifugal compressor comprises a rotor, a main shaft of the rotor is provided with a multi-stage impeller, an axial bearing and a radial bearing, and at least one of the axial bearing and the radial bearing is a gas bearing.

In some embodiments, the centrifugal compressor includes a motor disposed at a middle portion of the main shaft, and the multi-stage impellers are sequentially disposed on the main shaft in an air intake direction of the compressor and are symmetrically disposed with respect to the motor of the compressor.

In some embodiments, the gas bearing is selected from at least one of: a hydrodynamic gas bearing; a hydrostatic gas bearing; hybrid bearing of dynamic and static pressure.

In some embodiments, the multi-stage impeller includes a plurality of low pressure stage impellers arranged adjacent to an intake of the compressor and a plurality of high pressure stage impellers arranged adjacent to an exhaust of the compressor.

In some embodiments, the number of impellers in each of the plurality of high pressure stage impellers and the plurality of low pressure stage impellers is two.

In some embodiments, a first radial air bearing is disposed between the motor and the high pressure stage impeller, a second radial gas bearing is disposed between the motor and the low pressure stage impeller, and an axial thrust disk and an axial gas bearing are disposed between the first radial air bearing and the high pressure stage impeller.

In some embodiments, an air supplement port is provided between at least one set of two adjacent impellers in the multistage impeller.

In some embodiments, an air supplement port is provided between any two adjacent impellers in the multistage impellers.

In some embodiments, a cooling flow passage is provided between the stator of the motor and the housing of the compressor for introducing the refrigerant from the refrigerant supply portion of the compressor.

In some embodiments, the cooling flow passage is provided on at least one of a stator of the motor and a housing of the compressor.

In some embodiments, the cooling flow path is helical.

In some embodiments, the refrigerant supply part includes a condenser of the multi-split air conditioning system.

In some embodiments, the gap between the rotor and the stator of the electric machine and the gap between the bearing and the main shaft are both in fluid communication with the cooling flow path.

The invention provides a multi-split air conditioning system with a centrifugal compressor. The air suspension bearing technology is adopted, and the problems of temperature rise and large friction loss of the oil lubrication bearing at a high rotating speed are solved. By adopting the multi-stage impeller for compression, the problem of low pressure ratio of the common two-stage refrigeration compressor is improved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:

FIG. 1 is a schematic structural diagram of an embodiment of the present invention;

FIG. 2 is a schematic structural view of the compressor rotor of FIG. 1;

fig. 3 is a schematic structural diagram of the refrigerant cooling channel in fig. 1.

Detailed Description

Embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

As shown in fig. 1, the present invention discloses a multi-split air conditioning system with a centrifugal compressor 100, only the centrifugal compressor 100 is shown for simplicity, and other parts of the multi-split air conditioning system are not shown.

The centrifugal compressor 100 comprises a multi-stage impeller mounted on the main shaft 101 of the rotor, an axial bearing, a radial bearing, and a permanent magnet motor 102, wherein the axial bearing is a gas bearing, or the radial bearing is a gas bearing, or both the axial bearing and the radial bearing are gas bearings. The gas bearing may be selected from at least one of: a hydrodynamic gas bearing; a hydrostatic gas bearing; hybrid bearing of dynamic and static pressure.

Compared with a common refrigeration compressor, the centrifugal compressor adopts multi-stage compression and has multi-stage impellers, for example, four impellers, and four-stage compression. The compressor can reach a higher pressure ratio and meet the requirement that a unit works in an environment of-30-50 ℃. The compressor adopts the gas bearing, compared with an oil-lubricated bearing, the gas bearing allows the compressor to have higher rotating speed, the bearing has small heat productivity, the temperature rise and the bearing friction loss, and compared with the oil-lubricated bearing, the gas bearing has small friction and low temperature rise and is more suitable for a rotor under the work of high rotating speed.

In some embodiments, as shown in fig. 2, the centrifugal compressor 100 includes a motor 102, the motor 102 is disposed at a middle portion of a main shaft 101, and the multi-stage impellers are sequentially disposed on the main shaft 101 along an air intake direction of the compressor 100 and are symmetrically disposed with respect to the motor 102 of the compressor 100.

The high-pressure stage impeller and the low-pressure stage impeller are respectively disposed at both ends of the main shaft 101, a plurality of low-pressure stage impellers are disposed adjacent to the air inlet 118 of the compressor 100, and a plurality of high-pressure stage impellers are disposed adjacent to the air outlet 119 of the compressor 100, for example, the number of the high-pressure stage impellers is two, but may be other numbers. The motor 102 is located at the middle position of the main shaft 101, a first radial air bearing 111 is arranged between the motor 102 and the high-

pressure stage impellers

105 and 106, a second radial air bearing 112 is arranged between the motor 102 and the low-

pressure stage impellers

103 and 104, and an axial thrust disc 113 and an axial air bearing 114 are arranged between the first radial air bearing 111 and the high-

pressure stage impellers

105 and 106.

The low-pressure-

stage impellers

103 and 104 and the high-pressure-

stage impellers

105 and 106 are symmetrically arranged at two ends of the motor 102, so that the stress of the bearing is more uniform, the deformation state of the rotor in the operation process is more uniform, and meanwhile, the arrangement mode can reduce the length of the cantilever end of the rotor spindle to the maximum extent, and is favorable for improving the critical rotating speed of the rotor. Because the rigidity of the gas bearing is lower than that of the oil lubrication bearing, the critical rotating speed of the rotor is difficult to promote, and the structure can promote the reliability of the rotor in the working process.

The motor 102 is arranged in the middle of the rotor, so that the distance between the end of the rotor and the motor can be reduced to the maximum extent, and the motor is a driving part and applies torque to the rotor.

In some embodiments, the compressor 100 employs four-stage compression and multi-stage air supplement, and the compressor air supplement can improve the refrigeration cycle efficiency of the compressor 100, thereby improving the unit energy efficiency of the compressor. The number of air supply can be one, two or three. As shown in fig. 3, the first air supplement port 201 is located between the primary impeller 103 and the secondary impeller 104. A communication conduit 109 fluidly connects secondary impeller 104 and tertiary impeller 105, and a second air supplement port 202 is located on communication conduit 109 between secondary impeller 104 and tertiary impeller 105. The third air supplement port 203 is located between the third stage impeller 105 and the fourth stage impeller 106. The air supply is not necessarily required between every two impellers, and the air supply can be omitted between the two impellers.

The motor 102 and the bearing generate heat during operation, and in order to ensure the operational reliability of the motor 102 and the bearing, the motor 102 and the bearing need to be cooled, and compared with ordinary air cooling or water cooling, the cooling effect of a cooling medium is better.

As shown in fig. 3, in some embodiments, a cooling flow channel 108 is provided between the stator 1021 of the motor 102 and the casing 107 of the compressor 100 for introducing a refrigerant from the refrigerant supply part of the compressor 100.

In some embodiments, the cooling flow channel 108 is disposed on at least one of the stator 1021 of the motor 102 and the casing 107 of the compressor 100. For example, the cooling channels 108 are helical.

In some embodiments, the gap between the rotor and the stator of the electric machine 102 and the gap between the bearing and the main shaft 101 are both in fluid communication with the cooling flow channel 108.

Therefore, the motor 102 and the bearing can be cooled by the refrigerant, the refrigerant for cooling the motor 102 comes from a condenser or other high-pressure liquid refrigerants and enters the spiral flow channel of the motor after passing through the throttling device, and the spiral flow channel is arranged on the outer surface of the motor stator, so that the sufficient cooling of the motor stator is ensured. The fluid for cooling the bearing comes from the fluid compressed by the impeller, and the fluid flows through the bearing after passing through the back of the impeller and the gap of the gas structure, so that the heat generated by the work of the bearing is taken away, and the temperature of the bearing is reduced. And a part of fluid passes through a gap between the motor stator and the motor rotor to cool the motor rotor, and all the fluid flows out after being collected at the outlet of the motor 102, so that the cooling circulation of the motor 102 and the bearing is completed.

The above-described embodiments are described in detail with reference to examples, but the present invention is not limited to the described embodiments. It will be apparent to those skilled in the art that various changes, modifications, equivalents and variations can be made in these embodiments without departing from the spirit and scope of the invention.

Claims

1. The multi-split air conditioning system comprises a centrifugal compressor (100), wherein the centrifugal compressor (100) comprises a rotor, a main shaft (101) of the rotor is provided with a multi-stage impeller, an axial bearing and a radial bearing, and at least one of the axial bearing and the radial bearing is a gas bearing.

2. A multi-split air conditioning system as claimed in claim 1, wherein the centrifugal compressor (100) comprises a motor (102), the motor (102) is disposed at a middle portion of the main shaft (101), the multi-stage impellers are sequentially provided on the main shaft (101) along an air intake direction of the compressor (100), and are symmetrically disposed with respect to the motor (102) of the compressor (100).

3. A multi-split air conditioning system as claimed in claim 1, wherein the gas bearing is selected from at least one of: a hydrodynamic gas bearing; a hydrostatic gas bearing; hybrid bearing of dynamic and static pressure.

4. A multi-split air conditioning system as claimed in claim 2, wherein the multi-stage impeller includes a plurality of low pressure stage impellers arranged adjacent to an air inlet (118) of the compressor (100) and a plurality of high pressure stage impellers arranged adjacent to an air outlet (119) of the compressor (100).

5. The multi-split air conditioning system as claimed in claim 4, wherein the number of the plurality of high pressure stage impellers (105; 106) and the number of the plurality of low pressure stage impellers (103; 104) are both two.

6. The multi-split air conditioning system as claimed in claim 4, wherein a first radial air bearing (111) is provided between the motor (102) and the high pressure stage impeller, a second radial air bearing (112) is provided between the motor (102) and the low pressure stage impeller, and an axial thrust disc (113) and an axial air bearing (114) are provided between the first radial air bearing (111) and the high pressure stage impeller.

7. A multi-split air conditioning system as claimed in any one of claims 1 to 6, wherein an air supplement port is provided between at least one set of two adjacent impellers among the multistage impellers.

8. A multi-split air conditioning system as claimed in claim 7, wherein an air supplement port (201; 202; 203) is provided between any two adjacent impellers of the multi-stage impellers.

9. A multi-split air conditioning system as claimed in claim 2, wherein a cooling flow passage (108) for introducing a refrigerant from a refrigerant supply part of the compressor (100) is provided between the stator (1021) of the motor (102) and the casing (107) of the compressor (100).

10. A multi-split air conditioning system as claimed in claim 9, wherein the cooling flow passage (108) is provided on at least one of the stator (1021) of the motor (102) and the casing (107) of the compressor (100).

11. A multi-split air conditioning system as claimed in claim 9, wherein the cooling flow passage (108) is spiral.

12. A multi-split air conditioning system as claimed in claim 9, wherein the refrigerant supply part includes a condenser of the multi-split air conditioning system.

13. A multi-split air conditioning system as claimed in claim 9, wherein a gap between a rotor and a stator of the motor (102) and a gap between the bearing and the main shaft (101) are both in fluid communication with the cooling flow passage (108).