Centrifugal compressors and refrigeration units

Abstract

An embodiment of the present invention provides a centrifugal compressor and a refrigeration device. The compressor includes: a housing having a fluid inlet at a first position of the housing and a fluid outlet at a second position of the housing; a motor assembly, the motor assembly being arranged in the housing and including a stator and a rotor, the rotor including a vertically arranged rotor shaft, the rotor shaft including a lower end and an upper end; a centrifugal compression mechanism, the impeller of the centrifugal compression mechanism being connected to the rotor shaft to be driven by the motor assembly; and a guide member, the guide member being located above the centrifugal compression mechanism and defining a flow channel alone or together with the top portion of the housing; the fluid from the fluid inlet flows from the periphery of the centrifugal compression mechanism into the flow channel from bottom to top after passing through the motor assembly, and turns in the flow channel, thereby entering the centrifugal compression mechanism from top to bottom. According to the embodiment of the present invention, the device has a compact structure.

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 considering the use of high-speed, small centrifugal compressors, the cost of high-speed, oilless bearings is prohibitive. Therefore, it is desirable to provide bearings that require lubrication and design simplified oil circuits. Furthermore, it is desirable to simplify the structure of centrifugal compressors, 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 arranged vertically, comprising:

[0005] a housing having a fluid inlet at a first position of the housing and a fluid outlet at a second position of the housing higher than the first position;

[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 having an impeller connected to the rotor shaft to be driven by the motor assembly; and

[0008] a guide member located above the centrifugal compression mechanism and defining a flow channel solely together with the top portion of the housing;

[0009] Wherein, when the centrifugal compressor is working, the fluid from the fluid inlet passes through the motor assembly and flows from the periphery of the centrifugal compression mechanism into the flow channel from bottom to top, and turns in the flow channel, thereby entering the centrifugal compression mechanism from top to bottom and leaving from the fluid outlet.

[0010] In some embodiments 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 axially or inclined oil channel therein, and has radially through-holes at positions corresponding to the first bearing and the second bearing.

[0011] In some embodiments of the centrifugal compressor, the motor assembly comprises:

[0012] Motor housing;

[0013] a stator fixed inside the motor housing;

[0014] a rotor located radially inward of the stator, the rotor being capable of rotating relative to the stator under excitation;

[0015] A first bearing seat and a first bearing therein at the bottom of the motor housing;

[0016] The oil cup on the top of the motor housing; and

[0017] A second bearing support above the oil cup and a second bearing therein.

[0018] In some embodiments of the centrifugal compressor, the bottom of the motor housing is connected to the outer shell via 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 in the bottom part of the outer shell.

[0019] In some embodiments of the centrifugal compressor, the outer periphery of the second bearing support has a fluid channel allowing fluid to pass from bottom to top.

[0020] In some embodiments of the centrifugal compressor, the centrifugal compression mechanism includes one or more compression stages.

[0021] In some embodiments 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. 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 the fluid outlet through the outlet of the volute.

[0022] In some embodiments of the centrifugal compressor, outer circumferences of the volute and the second bearing support have corresponding fluid channels to allow fluid to pass from bottom to top.

[0023] In some embodiments of the centrifugal compressor, the guide is hemispherical, and the top portion of the housing has an inward protrusion.

[0024] In another aspect, a refrigeration device is provided, comprising the centrifugal compressor according to various embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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:

[0026] Figure 1 A cross-sectional view showing a centrifugal compressor according to an embodiment of the present invention; and

[0027] Figure 2 An exploded view of a centrifugal compressor according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0028] 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.

[0029] 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.

[0030] refer to Figure 1 and Figure 2 , shows a centrifugal compressor, including a casing 1, having a fluid inlet 15 at a first position of the casing, and a fluid outlet 17 at a second position of the casing higher than the first position; a motor assembly 2, the motor assembly is arranged in the casing 1 and includes a stator and a rotor, the rotor includes a vertically arranged rotor shaft 24, the rotor shaft 24 includes a lower end 242 and an upper end 243; a centrifugal compression mechanism 4, the impeller of the centrifugal compression mechanism 4 is connected to the rotor shaft (such as its upper end 243) to be driven by the motor assembly 2; and a guide 3, the guide 3 is located above the centrifugal compression mechanism and defines a flow channel 5 alone or together with the top part 13 of the casing 1; wherein, when the centrifugal compressor is working, the fluid from the fluid inlet 15 passes through the motor assembly 2 and flows from the periphery of the centrifugal compression mechanism 4 from bottom to top into the flow channel 5, and turns in the flow channel 5, thereby entering the centrifugal compression mechanism 4 from top to bottom, and the fluid compressed and pressurized by the centrifugal compression mechanism 4 leaves from the fluid outlet 17, roughly as marked by the hollow arrow.

[0031] In a centrifugal compressor according to an embodiment of the present invention, fluid first passes through and cools the motor assembly 2, including through the gap G1 between the rotor and stator and the outside of the motor housing 21. It then flows from a radially outer channel of the centrifugal compression mechanism 4 to the flow channel 5 defined between the guide member 3 and the top portion 13 of the housing. The fluid then turns and enters the centrifugal compression mechanism 4 from top to bottom for compression and pressurization. After undergoing two stages of compression and pressurization, the fluid is ultimately discharged from the fluid outlet 17. A feature of the centrifugal compressor according to an embodiment of the present invention is that it uses intake air to cool the motor assembly. For example, intake air from the evaporator is directed directly to the motor assembly 2 to cool it. Because the fluid according to an embodiment of the present invention passes through the centrifugal compression mechanism 4 from top to bottom, when the centrifugal compression mechanism 4 is operating, its impeller exerts an upward force on the rotor shaft 24, which partially offsets the weight of the rotor shaft 24 itself, thereby reducing the axial stress on the bearings 31 and 32 supporting the rotor shaft 24. Furthermore, the device according to this embodiment provides a compact centrifugal compressor suitable for low-power applications.

[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 positioned in a first bearing seat 27 at the bottom of the motor assembly 2, while the second bearing 32 is positioned 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. The fluid inlet 15 may be formed as a conduit that extends radially and is flush with the bottom of the motor housing 21. In some embodiments, the fluid inlet 15 may extend into the interior of the housing 1 and align with an opening 211 at the bottom of the motor housing 21, with a gap G2 therebetween. This allows airflow from the fluid inlet 15 to partially pass through the gap G1 between the stator and rotor of the motor and partially pass through the outside of the motor assembly 2. The top of the motor housing 21 may also have an opening 212 to allow airflow through the gap G1 to exit, and an oil conduit 251 may extend from this opening 212. The bottom portion 11 of the housing 1 includes an oil sump. Lubricating oil for the first and second bearings 31, 32, and optionally other components, may be contained in this sump. The lower end 242 of the rotor shaft 24 can be located in the oil groove, specifically, can be inserted into the stopper 111 in the oil groove. The rotor shaft 24 defines an oil channel 241 along the axial direction, for example, Figure 1The rotor shaft shown may be hollow and have an oil passage 241 therein. This oil passage 241 may be straight (along the axial direction of the rotor shaft 242) or inclined. The rotor shaft 24 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 24 generates negative pressure in the oil passage 241, thereby drawing oil from the oil sump through the oil passage 241 in the direction of the arrow. Due to centrifugal force, the oil flows out of the radial through-holes 246 and 247, thereby lubricating the first and second bearings 31 and 32. The oil that has passed through and lubricated 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 has passed through and lubricated the second bearing 32 falls into the oil cup 25 and is guided to the inside of the housing sidewall via an inclined oil guide pipe 251, where it returns to the oil sump along the inside of the housing sidewall. The arrangement of the oil cup 25 and the oil guide tube 251 prevents lubricating oil from entering the interior of the motor assembly 2. In some embodiments, the aperture of the through-hole 246 corresponding to the first bearing 31 may be smaller than the aperture 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 2 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 2 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 2 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 directly arranged on the second bearing support 26, and the outer periphery of the second bearing support 26 and the volute 43 includes fluid channels 71, 442 that allow fluid to pass from bottom to top, which can be formed as holes or channels distributed at corresponding positions along the outer periphery of the second bearing support 26 and the volute 43. 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 52 is disposed between the first-stage impeller 41 and the second-stage impeller 44, while the second sleeve 33 is disposed between the second-stage impeller 44 and the second bearing 32. In the illustrated embodiment, the outlet 443 of the volute 43 communicates with the fluid outlet 17 of the casing. The fluid entering the centrifugal compression mechanism through the flow passage 5 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 the fluid outlet 17 through the outlet 443 of the volute, thereby being supplied to equipment downstream of the compressor.

[0035] like Figure 2 As shown in , a guide member 3 is arranged above the centrifugal compression mechanism 4, for example, it can be directly supported by the volute 43. In the embodiment shown, the guide member 3 and the top portion 13 of the outer casing 1 together define a flow channel 5, which guides the fluid to be circuitous or turn, thereby passing through the centrifugal compression mechanism 4 from top to bottom. In alternative embodiments, the guide member 3 may define the flow channel 5 by itself, for example, the guide member 3 may be formed to have a flow channel 5 or the guide member 3 may be assembled by multiple components to define the flow channel 5 together. In some embodiments, the guide member 3 has a hemispherical shape, and the inner side of the top portion 13 of the outer casing may also be dome-shaped. In addition, in order to guide the fluid, adjust the angle of the gas entering the impeller, and reduce airflow losses, in some embodiments, the top portion 13 of the outer casing has an inward protrusion 14. In alternative embodiments, the guide member 3 and the top portion 13 of the outer casing may have any other suitable shape.

[0036] In another aspect, a refrigeration device is provided, comprising the centrifugal compressor according to various embodiments.

[0037] 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 having a fluid inlet at a first position of the housing and a fluid outlet at a second position of the housing higher than the first position; 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 having an impeller connected to the rotor shaft to be driven by the motor assembly; and a guide member located above the centrifugal compression mechanism and defining a flow channel alone or together with the top portion of the housing; When the centrifugal compressor is in operation, the fluid from the fluid inlet passes through the motor assembly and then flows from the periphery of the centrifugal compression mechanism into the flow channel from bottom to top, and turns in the flow channel, thereby entering the centrifugal compression mechanism from top to bottom and leaving from the fluid outlet. When the fluid passes through the centrifugal compression mechanism from top to bottom, the impeller applies an upward force to the rotor shaft. The motor assembly comprises: Motor housing; a stator fixed inside the motor housing; a rotor located radially inward of the stator, the rotor being capable of rotating relative to the stator under excitation; 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 The second bearing support above the oil cup and the second bearing therein, The oil cup includes an oil guide pipe, which is arranged obliquely to guide the oil in the oil cup to the inner wall of the shell, so that the oil returns to the oil groove in the bottom part of the shell along the inner wall.

2. The centrifugal compressor according to claim 1, characterized in that The rotor shaft is supported by a first bearing located at a lower portion and a second bearing located at an upper portion. The lower end of the rotor shaft is located in the oil groove. The rotor shaft defines an axial or inclined oil passage therein and has radial through holes at positions corresponding to the first bearing and the second bearing.

3. The centrifugal compressor according to claim 1, characterized in that The motor housing further includes a side wall, the side wall including: a first opening at the bottom of the side wall and a second opening at the top of the side wall, wherein the fluid inlet extends to the interior of the housing and is aligned with the first opening with a first gap therebetween, so that a first portion of the airflow from the fluid inlet passes through a second gap between the stator and the rotor and exits the motor assembly from the second opening, while a second portion of the airflow passes from the outside of the motor assembly.

4. The centrifugal compressor according to claim 3, characterized in that The bottom of the motor housing is connected to the outer shell through a supporting bracket, and the top of the motor housing is connected to the second bearing bracket, which is supported by the outer shell.

5. The centrifugal compressor according to claim 3, characterized in that The outer periphery of the second bearing support has a fluid passage located radially outside the motor housing and allowing fluid to pass from bottom to top.

6. The centrifugal compressor according to claim 3, characterized in that The centrifugal compression mechanism includes one or more compression stages.

7. The centrifugal compressor according to claim 6, 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 casing. 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 the fluid outlet through the outlet of the volute.

8. The centrifugal compressor according to claim 7, characterized in that The outer peripheries of the volute and the second bearing support have corresponding fluid passages to allow fluid to pass from bottom to top.

9. The centrifugal compressor according to claim 1, characterized in that The guide is hemispherical, and the top portion of the housing has an inward protrusion.

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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