Centrifugal compressor and refrigeration device

Abstract

A centrifugal compressor and a refrigeration device are provided. The centrifugal compressor includes a housing having a fluid inlet and a fluid outlet at a top of the housing, a motor assembly disposed in the housing and including a stator and a rotor, the rotor including a vertically disposed rotor shaft, a centrifugal compression mechanism having an impeller coupled to the rotor shaft for being driven by the motor assembly, the centrifugal compression mechanism being disposed downstream of the fluid inlet to receive fluid, compress and pressurize the fluid, and output the pressurized fluid in a direction away from the motor assembly, and a guide receiving the pressurized fluid from the centrifugal compression mechanism and defining, alone or with portions of the housing, a flow passage configured to pass the pressurized fluid from the centrifugal compression mechanism over and cool the motor assembly. The centrifugal compression mechanism structure according to embodiments is compact.

Description

Technical Field

[0001] The present invention relates to the field of compressors, and more particularly, to a centrifugal compressor and a refrigeration device having the same. Background Art

[0002] Centrifugal compressors, commonly used in large refrigeration units, often utilize bearings that require no lubrication (oilless bearings). However, when high-speed, small centrifugal compressors are desired, the cost of high-speed, oilless bearings is prohibitive. Therefore, it is desirable to provide bearings that require lubrication and design simplified lubrication oil pathways. Furthermore, it is desirable to simplify the centrifugal compressor structure, thereby enabling the development of compact, small centrifugal compressors. Summary of the Invention

[0003] The purpose of the present invention is to solve or at least alleviate the problems existing in the prior art.

[0004] In one aspect, a centrifugal compressor is provided, in particular a vertical centrifugal compressor suitable for vertical arrangement, comprising:

[0005] a housing, the housing having a fluid inlet and a fluid outlet, the fluid inlet being located at a top of the housing;

[0006] a motor assembly disposed in the housing and comprising a stator and a rotor, the rotor comprising a vertically disposed rotor shaft, the rotor shaft comprising a lower end and an upper end;

[0007] a centrifugal compression mechanism, wherein an impeller of the centrifugal compression mechanism is connected to the rotor shaft to be driven by the motor assembly, the centrifugal compression mechanism being arranged downstream of the fluid inlet to receive the fluid, compress and pressurize the fluid, and output the pressurized fluid in a direction away from the motor assembly;

[0008] A guide receives pressurized fluid from the centrifugal compression mechanism and defines, alone or in conjunction with a portion of the housing, a flow channel configured to allow the pressurized fluid from the centrifugal compression mechanism to pass through and cool the motor assembly and be discharged from the fluid outlet.

[0009] Optionally, in an embodiment of the centrifugal compressor, the guide member is a pipe.

[0010] Optionally, in an embodiment of the centrifugal compressor, the guide is partially or completely located outside the casing.

[0011] Optionally, in an embodiment of the centrifugal compressor, the guide member has a first end connected to the output port of the centrifugal compression mechanism, a second end connected to the side wall of the casing, such as the lower portion of the side wall of the casing, and a pipe body connected between the first end and the second end and including a curved portion.

[0012] Optionally, in an embodiment of the centrifugal compressor, the rotor shaft is supported by a first bearing located at a lower portion and a second bearing located at an upper portion, the bottom portion of the housing has an oil groove, the lower end of the rotor shaft is located in the oil groove, the rotor shaft defines an axial or inclined oil channel therein, and has radial through-holes at positions corresponding to the first bearing and the second bearing.

[0013] Optionally, in an embodiment of the centrifugal compressor, the motor assembly comprises:

[0014] Motor housing;

[0015] a stator fixed inside the motor housing;

[0016] a rotor radially inwardly of the stator, the rotor being capable of rotating relative to the stator when the motor assembly is energized;

[0017] A first bearing seat and a first bearing therein at the bottom of the motor housing;

[0018] The oil cup on the top of the motor housing; and

[0019] A second bearing support above the oil cup and a second bearing therein.

[0020] Optionally, in an embodiment of the centrifugal compressor, the bottom of the motor housing is connected to the outer shell through a support bracket, the top of the motor housing is connected to the second bearing bracket, the second bearing bracket is supported by the outer shell, and the oil cup includes an oil guide pipe, which is arranged at an angle to guide the oil in the oil cup to the inner wall of the outer shell and back to the oil tank.

[0021] Optionally, in an embodiment of the centrifugal compressor, the centrifugal compression mechanism comprises one or more compression stages.

[0022] Optionally, in an embodiment of the centrifugal compressor, the centrifugal compression mechanism includes a first-stage impeller, a partition, a volute and a second-stage impeller, the outlet of the volute is connected to the fluid outlet of the outer casing, the fluid is compressed by the first-stage impeller, passes between the upper surface of the volute and the partition, and then is compressed by the second-stage impeller and leaves through the output port of the volute.

[0023] In another aspect, a refrigeration device is provided, comprising the centrifugal compressor according to various embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The disclosure of the present invention will be more easily understood with reference to the accompanying drawings. Those skilled in the art will readily appreciate that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Furthermore, similar numbers in the drawings represent similar components, wherein:

[0025] Figure 1 A cross-sectional view showing a centrifugal compressor according to an embodiment of the present invention; and

[0026] Figure 2 An exploded view of a centrifugal compressor according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0027] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solution of the present invention and should not be regarded as the entire invention or as a limitation or restriction of the technical solution of the present invention.

[0028] The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly mentioned in this specification are defined relative to the structure shown in the drawings. They are relative concepts and may vary depending on the location and usage of the device. Therefore, these or other directional terms should not be interpreted as restrictive.

[0029] refer to Figure 1 and Figure 2 , shows a centrifugal compressor, including a casing 1, the casing having a fluid inlet 15 and a fluid outlet 17, the fluid inlet 15 being located at the top of the casing; a motor assembly 2, the motor assembly 2 being arranged in the casing 1 and including a stator 23 and a rotor, the rotor including a rotor shaft 24, the rotor shaft 24 including a lower end 242 and an upper end 243; a centrifugal compression mechanism 4, the impellers 41, 44 of the centrifugal compression mechanism 4 being connected to the rotor shaft 24 (such as its upper end 243) to be driven by the motor assembly 2, the centrifugal compression mechanism being arranged downstream of the fluid inlet 15 (such as directly below it) to receive the fluid, compress and pressurize the fluid and output the pressurized fluid in a direction away from the motor assembly 2; a guide 5, the guide 5 receiving the pressurized fluid from the centrifugal compression mechanism 4 and defining a flow channel alone or together with part of the casing, the flow channel being configured so that the pressurized fluid from the centrifugal compression mechanism 4 passes through the motor assembly 2 and is discharged from the fluid outlet 17, roughly as marked by the hollow arrow.

[0030] In a centrifugal compressor according to an embodiment of the present invention, after the fluid enters the casing through the suction chamber, it can immediately enter the centrifugal compression mechanism 4 and be compressed and pressurized by the centrifugal compression mechanism 4. For example, after two-stage compression and pressurization, it is then guided by the guide 5 and turned back into the casing 1, thereby cooling the motor assembly 2, including passing through the gap G2 between the rotor and the stator and the outside of the motor housing 21, and then discharged from the fluid outlet 17. A feature of the centrifugal compressor according to an embodiment of the present invention is that the compressed gas after compression is guided through the motor assembly, thereby cooling the motor assembly. Because the fluid according to the embodiment of the present invention passes through the centrifugal compression mechanism 4 from top to bottom, when the centrifugal compression mechanism 4 is working, its impeller will apply an upward force to the rotor shaft 24, which partially offsets the weight of the rotor shaft 24 itself, thereby reducing the axial stress of the bearings 31 and 32 supporting the rotor shaft 24. In addition, the device according to this embodiment provides a centrifugal compressor with a compact design for application in low-power conditions.

[0031] In some embodiments, the guide 5 may be as follows Figure 1 As shown, the guide member 5 is formed into a pipe. In an alternative embodiment, the guide member 5 can form a guide channel together with the outer wall of the housing 1 or the guide member 5 can separate the inner part of the housing 1 into compartments to guide the fluid. In an alternative embodiment, the guide member 5 can be a one-piece or a combination of multiple parts. Figure 1 In the illustrated embodiment, the guide 5 is partially or completely located outside the housing 1, in other words, it has a portion extending outside the housing 1. In the illustrated embodiment, the guide 5 has a first end 51 connected to the output port 443 of the centrifugal compression mechanism, a second end 52 connected to the side wall of the housing, such as the lower portion of the side wall of the housing 1, and a pipe body 53 connected between the first end 51 and the second end 52 and including curved portions 531, 532. In some embodiments, the guide 5 causes the fluid flowing out of the centrifugal compression mechanism 4 to turn, for example, about 180 degrees, for example, 150 to 210 degrees, for example, basically in a direction away from the motor assembly 2 to a direction close to the motor assembly 4, thereby returning to the interior of the housing 1 and cooling the motor assembly 2. Figure 1As shown, in some embodiments, the second end 52 of the guide member 5 can extend into the housing 1 and align with the opening 211 at the bottom of the motor housing 21, with a gap G1 therebetween. This allows airflow from the guide member 5 to partially pass through the gap G2 between the motor stator and rotor, and partially pass through the space between the motor assembly and the housing 1. The top of the motor housing 21 can also have an opening 212 to allow airflow through the gap G2 to exit, and the oil guide tube 251 can extend from this opening 212. In some embodiments, the fluid outlet 17 of the housing 1 can be aligned with or adjacent to the opening 212, allowing airflow to be easily discharged. In some embodiments, the fluid outlet 17 can be located elsewhere, for example, above the connection 18 between the second end 52 of the guide member 5 and the housing 1, such as flush with the higher-positioned opening 212 of the motor housing 21.

[0032] In the illustrated embodiment, the rotor shaft 24 is supported by a first bearing 31 at the bottom and a second bearing 32 at the top. The first bearing 31 is mounted in a first bearing seat 27 at the bottom of the motor assembly 2, while the second bearing 32 is mounted in a second bearing support 26 at the top of the motor assembly. The housing 1 generally comprises a bottom portion 11, a middle portion 12, and a top portion 13, and may be generally cylindrical in shape. The fluid inlet 15 may be formed as a conduit extending axially or vertically and aligned with the inlet of the centrifugal compression mechanism 4. The bottom portion 11 of the housing 1 includes an oil trough. Oil for the first and second bearings 31, 32, and optional other components may be contained in the oil trough. The lower end 242 of the rotor shaft 24 may be positioned in the oil trough, specifically, inserted into a retainer 111 within the oil trough. The rotor shaft 242 defines an axial or slightly inclined oil passage 241 therein. For example, as shown in the figure, the rotor shaft may be hollow, with the oil passage 241 therein defined. The oil passage 241 may be straight (along the axial direction of the rotor shaft 242) or inclined. The rotor shaft 242 has radial through-holes 246 and 247 at positions corresponding to the first and second bearings 31 and 32, respectively. During operation of the centrifugal compressor, the rotation of the rotor shaft 242 generates negative pressure in the oil passage 241, drawing oil from the oil sump through the oil passage 241 in the direction of the arrow. Centrifugal force causes the oil to flow out of the radial through-holes 246 and 247, thereby lubricating the first and second bearings 31 and 32. The oil that passes through and lubricates the first bearing 31 returns directly to the oil sump due to gravity. An oil cup 25 is located below the second bearing 32. The oil that passes through and lubricates the second bearing 32 falls into the oil cup 25 and is then guided by an inclined oil guide pipe 251 to the inside of the housing sidewall, along which it returns to the oil sump. The arrangement of the oil cup 25 and oil guide pipe 251 prevents lubricating oil from entering the interior of the motor assembly. In some embodiments, the diameter of the through-hole 246 corresponding to the first bearing 31 may be smaller than the diameter of the through-hole 247 corresponding to the second bearing 32 to prevent excessive oil from flowing out of the through-hole 246 and failing to reach the through-hole 247 .

[0033] refer to Figure 1 and Figure 2 In the illustrated embodiment, the motor assembly may include: a motor housing 21; a stator 22 secured to the inside of the motor housing 21; and a rotor radially inward of the stator. In some embodiments, the rotor may include a rotor shaft 24 and permanent magnets 23; the stator 22 may include windings, and when the stator 22 is energized, the rotor may rotate relative to the stator 22. The motor assembly may also include a first bearing block 27 at the bottom of the motor housing 21 and a first bearing 31 therein; an oil cup 25 at the top of the motor housing 21; and a second bearing support 26 above the oil cup 25 and a second bearing 32 therein. In alternative embodiments, the motor assembly may have other suitable structures and components. In the illustrated embodiment, the bottom of the motor housing 21 is connected to the housing 1 via several support brackets 16, for example, to the inside of the sidewall of the housing 1. The top of the motor housing 21 is connected to the second bearing support 26, which is mounted to the housing 1, such as directly supported on the central portion 12 of the housing 1 or attached to the inner wall of the housing 1.

[0034] The centrifugal compression mechanism 4 is arranged on the second bearing support 26. For example, in some embodiments, the volute 43 of the centrifugal compression mechanism can be arranged directly on the second bearing support 26. Although the centrifugal compression mechanism 4 is shown in the figure as including two stages consisting of a first-stage impeller 41 and a second-stage impeller 44, in alternative embodiments, the centrifugal compression mechanism 4 may include only one stage or more stages. In the illustrated embodiment, the centrifugal compression mechanism 4 includes a first-stage impeller 41, a partition 42, a volute 43 and a second-stage impeller 44 passed through by the rotor shaft 24. The first-stage impeller 41 and the second-stage impeller 44 are connected to the rotor shaft 24 and rotate with the rotor shaft, while the partition 42 and the volute 43 are relatively fixed. The first sleeve 61 is arranged between the first-stage impeller 41 and the second-stage impeller 44 and the second sleeve 62 is arranged between the second-stage impeller 44 and the second bearing 32. In the illustrated embodiment, the output port 443 of the volute 43 communicates with the first end 51 of the guide member 5. Fluid entering the centrifugal compression mechanism 4 through the fluid inlet 15 is compressed by the first-stage impeller 41, passes between the upper surface of the volute 43 and the partition plate 42, and then is compressed by the second-stage impeller 44 before exiting through the output port 443 of the volute and entering the flow channel defined by the guide member 5. In alternative embodiments, the volute 43 may include a second fluid inlet for connection to an economizer.

[0035] In another aspect, a refrigeration device is provided, comprising the centrifugal compressor according to various embodiments.

[0036] The specific embodiments described above are intended only to more clearly illustrate the principles of the present invention. The various components are clearly shown or described to facilitate understanding of the principles of the present invention. Those skilled in the art may readily make various modifications or variations to the present invention without departing from the scope of the present invention. It should be understood that such modifications or variations are intended to be encompassed within the scope of the present invention.

Claims

1. A centrifugal compressor, characterized in that: include: a housing, the housing having a fluid inlet and a fluid outlet, the fluid inlet being located at a top of the housing; a motor assembly disposed in the housing and comprising a stator and a rotor, the rotor comprising a vertically disposed rotor shaft, the rotor shaft comprising a lower end and an upper end; a centrifugal compression mechanism, wherein an impeller of the centrifugal compression mechanism is connected to the rotor shaft to be driven by the motor assembly, the centrifugal compression mechanism being arranged downstream of the fluid inlet to receive the fluid, compress and pressurize the fluid, and output the pressurized fluid in a direction away from the motor assembly; a guide member that receives pressurized fluid from the centrifugal compression mechanism and, alone or in conjunction with a portion of the housing, defines a flow passage configured to allow the pressurized fluid from the centrifugal compression mechanism to pass through and cool the motor assembly and be discharged from the fluid outlet; wherein the guide member has a first end connected to the output port of the centrifugal compression mechanism, a second end connected to the side wall of the housing, and a pipe body connected between the first end and the second end; wherein the second end extends into the housing and is aligned with an opening in the bottom of the motor housing of the motor assembly such that a first gap (G1) is defined between the second end and the opening; a first portion of the pressurized fluid flows from the second end into the opening and passes through a second gap (G2) between the stator and the rotor; and A second portion of the pressurized fluid flows from the second end through the first gap and through the space between the motor housing and the outer shell.

2. The centrifugal compressor according to claim 1, characterized in that The guide member is a pipe.

3. The centrifugal compressor according to claim 2, characterized in that The guide is partially or completely located outside the housing.

4. The centrifugal compressor according to claim 2, characterized in that The second end of the guide is connected to a lower portion of a side wall of the housing, and the duct body includes a bent portion.

5. The centrifugal compressor according to claim 1, wherein: The rotor shaft is supported by a first bearing located at a lower portion and a second bearing located at an upper portion. The bottom portion of the housing has an oil groove, and the lower end of the rotor shaft is located in the oil groove. The rotor shaft defines an axially or obliquely extending oil passage therein and has radially extending through holes at positions corresponding to the first bearing and the second bearing.

6. The centrifugal compressor according to claim 1, characterized in that The motor assembly comprises: Motor housing; a stator fixed inside the motor housing; a rotor radially inwardly of the stator, the rotor being capable of rotating relative to the stator when the motor assembly is energized; A first bearing seat and a first bearing therein at the bottom of the motor housing; The oil cup on the top of the motor housing; and A second bearing support above the oil cup and a second bearing therein.

7. The centrifugal compressor according to claim 6, characterized in that The bottom of the motor housing is connected to the outer shell through a support bracket, the top of the motor housing is connected to the second bearing bracket, the second bearing bracket is supported by the outer shell, and the oil cup includes an oil guide pipe, which is arranged at an angle to guide the oil in the oil cup to the inner wall of the outer shell and return to the oil tank in the bottom part of the outer shell.

8. The centrifugal compressor according to claim 1, wherein: The centrifugal compression mechanism includes one or more compression stages.

9. The centrifugal compressor according to claim 8, characterized in that The centrifugal compression mechanism includes a first-stage impeller, a partition, a volute and a second-stage impeller. The outlet of the volute is connected to the fluid outlet of the outer shell. After being compressed by the first-stage impeller, the fluid passes between the upper surface of the volute and the partition, and then is compressed by the second-stage impeller and leaves through the output port of the volute.

10. A refrigeration device, characterized in that: The refrigeration device comprises the centrifugal compressor according to any one of claims 1 to 9.

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