compressor

Abstract

The utility model relates to centrifugal compressor technical field, concretely relates to a compressor. The compressor includes first volute, pivot, coaxial first impeller and second impeller and sealing plate that set up, the back of first impeller and the back of second impeller are opposite and set up, along the axial direction of first impeller, define the sealing space between the back of first impeller and the back of second impeller, the sealing plate is located in sealing space and is used for connecting the first volute of compressor, is equipped with first sealing structure between the back of sealing plate and first impeller, is equipped with second sealing structure between the back of sealing plate and second impeller. According to the compressor of this embodiment, by sharing a sealing plate between two oppositely arranged impeller back portions, and providing a sealing structure passage between the sealing plate and each of the two impellers, simultaneous sealing of the back portions of the two impellers is achieved, thereby significantly shortening the axial installation length required for the motor shaft.

Description

Technical Field

[0001] This utility model relates to the field of centrifugal compressor technology, specifically to a compressor. Background Technology

[0002] Currently, multistage compressors (such as magnetic levitation compressors and industrial compressors) typically employ multiple impellers in cascade arrangement to achieve high-pressure compression. To prevent high-pressure gas from leaking from the back of the impeller to the low-pressure area during compression, the industry practice is to install a separate back seal structure on the back of each impeller, such as a radial seal structure or a gas seal structure.

[0003] While this method achieves effective sealing, the need for each sealing structure to occupy installation space inevitably increases the total axial length of the shaft. This not only leads to increased overall machine size and manufacturing costs, but also complicates bearing arrangement, rotor stiffness, and moment of inertia calculations, hindering the achievement of high-speed operation stability and the goal of a compact overall design. Utility Model Content

[0004] The purpose of this invention is to at least solve the problem in the prior art where the axial length of the motor shaft increases due to the impeller seal. This purpose is achieved through the following technical solution:

[0005] This utility model proposes a compressor, comprising:

[0006] A first volute, wherein a first inner cavity and a second inner cavity are mutually isolated from each other;

[0007] A first impeller and a second impeller are coaxially arranged, with the first impeller disposed in the first inner cavity and the second impeller disposed in the second inner cavity. The backs of the first impeller and the backs of the second impeller are arranged opposite to each other, and a sealing space is defined between the backs of the first impeller and the backs of the second impeller along the axial direction of the first impeller.

[0008] A sealing plate is disposed within the sealed space and connected to the first volute of the compressor. The sealing plate separates the first inner cavity and the second inner cavity. A first sealing structure is provided between the sealing plate and the back of the first impeller, and a second sealing structure is provided between the sealing plate and the back of the second impeller.

[0009] A rotating shaft, the first end of which is located in the first inner cavity, and both the first impeller and the second impeller are connected to the first end of the rotating shaft.

[0010] According to the compressor of this utility model, by sharing a sealing plate between the backs of two oppositely arranged impellers and setting sealing structures on the sealing plate and the two impellers respectively, the backs of the two impellers are sealed simultaneously. This avoids the structural redundancy caused by setting a separate seal for each impeller in the traditional structure, thereby significantly shortening the axial installation length required for the shaft, making the overall structure of the compressor more compact, and facilitating the miniaturization, modular design and installation layout of the equipment.

[0011] In addition, the compressor according to this utility model may also have the following additional technical features:

[0012] In some embodiments of this utility model, the first sealing structure includes:

[0013] Multiple first protrusion structures are formed in a ring shape on the back of the first impeller and are coaxially arranged with the first impeller. The multiple first protrusion structures are arranged at intervals along the radial direction of the first impeller.

[0014] Multiple second protrusion structures are formed in a ring shape at one end of the sealing plate facing the first impeller and are coaxially arranged with the first impeller. The multiple second protrusion structures are arranged at intervals along the radial direction of the first impeller.

[0015] The plurality of first protrusion structures and the plurality of second protrusion structures are alternately arranged along the radial direction, and define a first sealing gap that meanders along the radial direction between the back of the first impeller and the sealing plate.

[0016] In some embodiments of this utility model, along the axial direction, the end face of the first protrusion structure facing the sealing plate is provided with at least two coaxially arranged first annular grooves, all of the first annular grooves are arranged sequentially at intervals along the radial direction and the first protrusion structure is divided into a plurality of first comb tooth structures, the first comb tooth structures extending obliquely outward relative to the axial direction toward the radial direction.

[0017] And / or, along the axial direction, the end face of the second protrusion structure facing the first impeller is provided with at least two coaxially arranged second annular grooves, all of the second annular grooves are arranged sequentially at intervals along the radial direction and the second protrusion structure is divided into a plurality of second comb tooth structures; the second comb tooth structure extends obliquely outward relative to the axial direction toward the radial direction.

[0018] In some embodiments of this utility model, the second sealing structure includes:

[0019] Multiple third protrusion structures are formed in a ring shape on the back of the second impeller and are coaxially arranged with the second impeller. The multiple third protrusion structures are arranged at intervals along the radial direction of the second impeller.

[0020] Multiple fourth protrusion structures are formed in a ring shape at one end of the sealing plate facing the second impeller and are coaxially arranged with the second impeller. The multiple fourth protrusion structures are arranged at intervals along the radial direction of the second impeller.

[0021] The plurality of third protrusions and the plurality of fourth protrusions are arranged alternately along the radial direction, and define a second sealing gap that meanders along the radial direction between the back of the second impeller and the sealing plate.

[0022] In some embodiments of this utility model, along the axial direction, the end face of the third protrusion structure facing the sealing plate is provided with at least two coaxially arranged third annular grooves, all of the third annular grooves are arranged sequentially at intervals along the radial direction and the third protrusion structure is divided into multiple third comb tooth structures, and the third comb tooth structure extends obliquely outward relative to the axial direction toward the radial direction.

[0023] And / or, along the axial direction, the end face of the fourth protrusion structure facing the second impeller is provided with at least two coaxially arranged fourth annular grooves, all of the fourth annular grooves are arranged sequentially at intervals along the radial direction and the fourth protrusion structure is divided into a plurality of fourth comb tooth structures; the fourth comb tooth structure extends obliquely outward relative to the axial direction toward the radial direction.

[0024] In some embodiments of this utility model, the first impeller includes an impeller body and a boss connected to each other. The back of the first impeller is located on the impeller body. Along the axial direction, one end of the boss away from the impeller body abuts against the back of the second impeller. The sealing plate is sleeved on the outside of the boss. A third sealing structure is formed between the circumferential outer wall of the boss and the circumferential inner wall of the sealing plate.

[0025] In some embodiments of this utility model, the circumferential inner wall of the sealing plate is provided with a plurality of fifth comb tooth structures, and the plurality of fifth comb tooth structures form the third sealing structure.

[0026] In some embodiments of this utility model, the sealing plate is a graphite sealing plate.

[0027] In some embodiments of this utility model, the compressor further includes:

[0028] The second volute has a third inner cavity, and the second end of the rotating shaft is located in the third inner cavity;

[0029] The third impeller is disposed in the third inner cavity and connected to the second end of the rotating shaft;

[0030] A wheel back seal is provided, which is connected to the housing of the compressor and is disposed opposite to the back of the third impeller. A fourth sealing structure is provided between the wheel back seal and the back of the third impeller.

[0031] In some embodiments of this invention, the sealing plate is detachably connected to the first volute. Attached Figure Description

[0032] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0033] Figure 1 A schematic diagram of the compressor according to an embodiment of the present invention is shown.

[0034] Figure 2 for Figure 1 A magnified view of a section at point A in the middle;

[0035] Figure 3 for Figure 2 A magnified view of a section at point B in the middle.

[0036] The attached figures are labeled as follows:

[0037] 51. Compressor;

[0038] 511. First volute; 512. Rotating shaft; 513. Impeller sealing assembly;

[0039] 5131, First impeller; 51311, Impeller body; 51312, Boss;

[0040] 5132, Sealing plate; 5133, Second impeller; 5134, First sealing structure; 51341, First protrusion structure; 513411, First annular groove; 51342, Second protrusion structure; 513421, Second annular groove; 5135, Second sealing structure; 51351, Third protrusion structure; 513511, Third annular groove; 51352, Fourth protrusion structure; 513521, Fourth annular groove; 5136, Third sealing structure; 51361, Fifth comb tooth structure; 514, Second volute; 515, Third impeller; 5151, Fourth sealing structure. Detailed Implementation

[0041] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0042] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0043] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0044] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "over," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure is flipped, an element described as "below other elements or features" or "below other elements or features" would subsequently be oriented "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations.

[0045] like Figures 1 to 3As shown, the compressor 51 according to an embodiment of the present invention includes a first volute 511, a rotating shaft 512, and an impeller sealing assembly 513. The first volute 511 has a first inner cavity and a second inner cavity that are isolated from each other. The impeller sealing assembly 513 includes a first impeller 5131 and a second impeller 5133 that are coaxially arranged. The backs of the first impeller 5131 and the backs of the second impeller 5133 are arranged opposite to each other. A sealing space is defined between the backs of the first impeller 5131 and the backs of the second impeller 5133 along the axial direction of the first impeller 5131. The impeller sealing assembly 513 also includes a sealing plate 5132. The sealing plate 5132 is disposed in the sealing space and connected to the first volute 511. The sealing plate 5132 separates the first inner cavity and the second inner cavity. A first sealing structure 5134 is provided between the sealing plate 5132 and the back of the first impeller 5131, and a second sealing structure 5135 is provided between the sealing plate 5132 and the back of the second impeller 5133.

[0046] The first impeller 5131 is disposed in the first inner cavity, the second impeller 5133 is disposed in the second inner cavity, and the sealing plate 5132 is disposed between the first impeller 5131 and the second impeller 5132 for sealing and isolating adjacent impellers. The first impeller 5131 and the second impeller 5133 are arranged back to back, with their back areas facing the two sides of the sealing plate 5132 respectively.

[0047] The compressor 51 also includes a rotating shaft 512, which passes through a sealing plate 5132 and is used to transmit power from the outside to the two impellers. The first end of the rotating shaft 512 is located in the first inner cavity and the second inner cavity, and connects the first impeller 5131 and the second impeller 5133, thereby realizing the coaxial linkage drive of the two-stage impellers. During operation, the rotating shaft 512 drives the first impeller 5131 and the second impeller 5133 to rotate synchronously, compressing the gas in the first inner cavity and the second inner cavity respectively. Since the sealing plate 5132 effectively isolates the two inner cavities, and a first sealing structure 5134 and a second sealing structure 5135 are respectively provided between the two impellers and the sealing plate 5132, it can effectively prevent gas from flowing from one side of the compression area to the other side of the compression area, improving compression efficiency and system stability.

[0048] According to the compressor 51 of this embodiment, by sharing a sealing plate 5132 between the backs of two oppositely arranged impellers, and by setting sealing structures on the sealing plate 5132 and the two impellers (hereinafter collectively referred to as impellers) respectively, the backs of the two impellers are simultaneously sealed, avoiding the structural redundancy caused by setting a separate seal for each impeller in the traditional structure. This significantly shortens the axial installation length required for the motor shaft 512, making the overall structure of the compressor 51 more compact, which is conducive to the miniaturization, modular design and installation layout of the equipment.

[0049] In some embodiments, the first sealing structure 5134 includes a plurality of first protrusions and a plurality of second protrusions 51342. The plurality of first protrusions 51341 are annular and formed on the back of the first impeller 5131, and are coaxially arranged with the first impeller 5131. The plurality of first protrusions 51341 are arranged sequentially at intervals along the radial direction of the first impeller 5131. The plurality of second protrusions 51342 are annular and formed at one end of the sealing plate 5132 facing the impeller, and are coaxially arranged with the first impeller 5131. The protruding structures 51342 are arranged sequentially at intervals along the radial direction of the first impeller 5131. The multiple first protruding structures 51341 and the multiple second protruding structures 51342 are arranged alternately along the radial direction of the first impeller 5131. That is, each first protruding structure 51341 is located between two adjacent second protruding structures 51342 in the radial direction, and vice versa. This defines a first sealing gap that extends in a zigzag pattern along the radial direction of the first impeller 5131 between the back of the first impeller 5131 and the sealing plate 5132.

[0050] By employing a complex arrangement of multiple radially interlocking annular protrusions, a complex reversal path is formed within the sealing area. This forces the gas to undergo multiple directional changes and throttling resistances before leakage, significantly increasing sealing resistance and reducing the leakage rate. Simultaneously, the compact radial distribution of the annular protrusions provides a cumulative sealing effect while occupying minimal space. This allows for the placement of more sealing stages within a limited structural cavity, enhancing the overall sealing level. This is particularly suitable for compressors 51, which require high sealing efficiency but are structurally constrained.

[0051] Specifically, along the axial direction of the first impeller 5131, at least two coaxially arranged first annular grooves 513411 are provided on the end face of the first protrusion facing the sealing plate 5132. All the first annular grooves 513411 are arranged sequentially at intervals along the radial direction of the first impeller 5131, dividing the first protrusion structure 51341 into multiple first comb-tooth structures. In this embodiment, the first annular grooves 513411 are used to divide the original first protrusion structure 51341 into multiple axially outward-extending first comb-tooth structures, effectively increasing the number of "tooth levels" of the sealing structure, giving the first sealing gap more throttling points and energy dissipation parts, thereby significantly improving leakage resistance and sealing efficiency. The more comb teeth there are, the more times the fluid veers through the path, the stronger the eddy current disturbance and expansion / contraction effect, effectively reducing the gas leakage rate. At the same time, the first comb-tooth structure is formed by processing the coaxial first annular grooves 513411, which has good rotational symmetry, helping to improve the machining accuracy of parts and the overall dynamic balance quality, and is particularly suitable for high-speed rotating equipment such as magnetic levitation compressors.

[0052] Furthermore, the first comb tooth structure extends radially outward relative to the axial direction. That is, the extension direction of each first comb tooth structure is not perpendicular to the rotation axis of the first impeller 5131, but is arranged radially outward at a preset angle, forming an oblique distribution structure. Because the first comb tooth structure is arranged obliquely, compared to a traditional vertical tooth structure, its leakage path is no longer a straight axial or radial channel, but forms a three-dimensional tortuous path of "oblique bends and twists," effectively extending the gas flow distance, significantly increasing aerodynamic resistance, and reducing the leakage rate. Simultaneously, during the high-speed rotation of the first impeller 5131, the oblique teeth can guide the airflow outward, deviating from the axial direction, strengthening the consistency of the discharge direction, reducing backflow and turbulent airflow accumulation, and improving sealing stability.

[0053] Preferably, the tilt angle is 5° to 30°, more preferably 10° to 20°, and the radial spacing between the multiple first comb tooth structures is uniform, forming an annular sealing structure with oblique tooth arrangement.

[0054] Specifically, along the axial direction of the first impeller 5131, the second protruding structure 51342 facing the first impeller 5131 has at least two coaxially arranged second annular grooves 513421. All the second annular grooves 513421 are arranged radially at intervals and divide the second protruding structure 51342 into multiple second comb-tooth structures. The function of the second comb-tooth structure is the same as that of the first comb-tooth structure, and will not be repeated here.

[0055] Furthermore, the second comb tooth structure extends outward at an angle relative to the axial direction towards the radial direction. The angled extension of the second comb tooth structure serves the same purpose as the outward angled extension of the first comb tooth structure, and will not be repeated here.

[0056] In some embodiments, the second sealing structure 5135 includes a plurality of third protrusions 51351 and a plurality of fourth protrusions 51352. The plurality of third protrusions 51351 are annular and formed on the back of the second impeller 5133 and are coaxially arranged with the second impeller 5133. The plurality of third protrusions 51351 are arranged in a radially spaced manner along the second impeller 5133. The plurality of fourth protrusions 51352 are annular and formed on one end of the sealing plate 5132 facing the second impeller 5133 and are coaxially arranged with the sealing plate 5132. The plurality of fourth protrusions 51352 are arranged in a radially spaced manner along the second impeller 5133. The plurality of third protrusions 51351 and the plurality of fourth protrusions 51352 are arranged radially alternately and define a second sealing gap extending radially outward between the back of the second impeller 5133 and the sealing plate 5132.

[0057] Specifically, along the axial direction of the second impeller 5133, the end face of the third protrusion structure 51351 facing the sealing plate 5132 is provided with at least two coaxially arranged third annular grooves 513511. All the third annular grooves 513511 are arranged radially at intervals and the third protrusion structure 51351 is divided into multiple third comb tooth structures.

[0058] Furthermore, the third comb tooth structure is arranged to extend outward in a radial direction relative to the axial direction.

[0059] Specifically, along the axial direction of the second impeller 5133, the end face of the fourth protrusion structure 51352 facing the second impeller 5133 is provided with at least two coaxially arranged fourth annular grooves 513521. All the fourth annular grooves 513521 are arranged radially at intervals and divide the fourth protrusion structure 51352 into multiple fourth comb tooth structures.

[0060] Furthermore, the fourth comb tooth structure is arranged to extend outward in a radial direction relative to the axial direction.

[0061] In some embodiments, the first impeller 5131 includes an impeller body 51311 and a boss 51312 connected to each other. The boss 51312 extends along the axial direction and is formed away from the impeller body 51311. The boss 51312 abuts against the back of the second impeller 5133. A sealing plate 5132 is sleeved on the outside of the boss 51312, and a third sealing structure 5136 is provided between the circumferential outer wall of the boss 51312 and the circumferential inner wall of the sealing plate 5132. In this embodiment, by providing a third sealing structure 5136 between the boss 51312 of the first impeller 5131 and the sealing plate 5132, the leaking gas must pass through multiple deflection paths in the axial region, significantly increasing the length of the leakage channel, forming strong aerodynamic resistance, and effectively limiting axial leakage.

[0062] Specifically, the outer circumferential wall of the boss 51312 is smooth, and the inner circumferential wall of the sealing plate 5132 is provided with multiple fifth comb-tooth structures 51361. The fifth comb-tooth structures 51361 and the smooth inner wall form a tortuous and complex axial labyrinthine sealing channel, thereby constituting the third sealing structure 5136. This third sealing structure 5136 is used to seal the axial leakage gap formed between the first impeller 5131 and the sealing plate 5132 due to the structural arrangement. The fifth comb-tooth structures 51361 are provided on the sealing plate 5132, and their rack shape can be rectangular, sawtooth, stepped, or other airflow disturbance structures to further improve the return rate and resistance characteristics of the sealing path.

[0063] Preferably, the fifth comb tooth structure 51361 includes a plurality of comb teeth spaced apart along the axial direction, each comb tooth being convex in the radial direction, forming a radially projecting annular toothed strip. An axially recessed region of equal width is defined between the plurality of comb teeth, the depth of which is approximately equal to the height of the comb teeth.

[0064] Furthermore, the sealing plate 5132 is a graphite sealing plate 5132. The graphite sealing plate 5132 used in this embodiment has excellent wear resistance and can maintain the integrity of the sealing surface structure for a long time under high-speed impeller rotation conditions. Since the sealing plate 5132 and the impeller back have a non-contact or micro-contact fit, the comb-like structure on the impeller back inevitably experiences minor interference, aerodynamic disturbances, or slight scratches during its circumferential movement. If the sealing material's wear resistance is insufficient, the sealing performance will rapidly decline. Using a graphite sealing plate 5132 can significantly improve the wear resistance of the sealing structure while ensuring sealing fit accuracy, adapting to long-term operation under high-speed rotation conditions, and extending the service life of the sealing plate 5132.

[0065] It is understood that the compressor 51 is a three-stage compression compressor 51. The compressor 51 also includes a second volute 514 and a third impeller 515. The second volute 514 has a third inner cavity, and the second end of the rotating shaft 512 is located in the third inner cavity. The third impeller 515 is located in the third inner cavity and connected to the second end of the rotating shaft 512. The third impeller 515 is sealed by a wheel back seal provided on the housing. The wheel back seal is arranged opposite to the back of the third impeller 515, and a fourth sealing structure 5151 is provided between the wheel back seal and the back of the third impeller 515. That is, it is formed by the protruding structure on the back of the third impeller 515 and the corresponding protruding structure on the wheel back seal in a non-contact staggered arrangement, which is used to effectively suppress the leakage of compressed gas from the third-stage exhaust zone to the rear.

[0066] In this embodiment, a common sealing plate 5132 is provided between the first impeller 5131 and the second impeller 5133, and first and second sealing structures 5135 are formed on both sides of it, so that the two impellers share a single sealing element. This eliminates the need for a back seal and its installation space, significantly shortens the length of the shaft 512, and improves the overall structural compactness. However, the third stage still uses a conventional back sealing structure for independent sealing, which is compatible with mature manufacturing processes and reliable sealing performance.

[0067] Understandably, the sealing plate 5132 is detachably connected to the first volute 511, facilitating the installation, disassembly, and maintenance of the impeller sealing assembly 513. Furthermore, after the compressor 51 has been running for a period of time, the sealing plate 5132 may require repair or replacement due to wear, carbon buildup, or failure. The detachable design allows for easy removal of the sealing plate 5132 and its sealing structure without dismantling the entire first volute 511, significantly reducing maintenance costs and downtime.

[0068] The above description is merely a preferred embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A compressor, characterized in that, include: A first volute, wherein a first inner cavity and a second inner cavity are mutually isolated from each other; A first impeller and a second impeller are coaxially arranged, with the first impeller disposed in the first inner cavity and the second impeller disposed in the second inner cavity. The backs of the first impeller and the backs of the second impeller are arranged opposite to each other, and a sealing space is defined between the backs of the first impeller and the backs of the second impeller along the axial direction of the first impeller. A sealing plate is disposed within the sealed space and connected to the first volute. The sealing plate separates the first inner cavity and the second inner cavity. A first sealing structure is provided between the sealing plate and the back of the first impeller, and a second sealing structure is provided between the sealing plate and the back of the second impeller. A rotating shaft, the first end of which is located in the first inner cavity, and both the first impeller and the second impeller are connected to the first end of the rotating shaft.

2. The compressor according to claim 1, characterized in that, The first sealing structure includes: Multiple first protrusion structures are formed in a ring shape on the back of the first impeller and are coaxially arranged with the first impeller. The multiple first protrusion structures are arranged at intervals along the radial direction of the first impeller. Multiple second protrusion structures are formed in a ring shape at one end of the sealing plate facing the first impeller and are coaxially arranged with the first impeller. The multiple second protrusion structures are arranged at intervals along the radial direction of the first impeller. The plurality of first protrusion structures and the plurality of second protrusion structures are alternately arranged along the radial direction, and define a first sealing gap that meanders along the radial direction between the back of the first impeller and the sealing plate.

3. The compressor according to claim 2, characterized in that, Along the axial direction, the end face of the first protrusion structure facing the sealing plate is provided with at least two coaxially arranged first annular grooves. All the first annular grooves are arranged sequentially at intervals along the radial direction and divide the first protrusion structure into a plurality of first comb tooth structures. The first comb tooth structures extend obliquely outward relative to the axial direction toward the radial direction. And / or, along the axial direction, the end face of the second protrusion structure facing the first impeller is provided with at least two coaxially arranged second annular grooves, all of the second annular grooves are arranged sequentially at intervals along the radial direction and the second protrusion structure is divided into a plurality of second comb tooth structures; the second comb tooth structure extends obliquely outward relative to the axial direction toward the radial direction.

4. The compressor according to claim 1, characterized in that, The second sealing structure includes: Multiple third protrusion structures are formed in a ring shape on the back of the second impeller and are coaxially arranged with the second impeller. The multiple third protrusion structures are arranged at intervals along the radial direction of the second impeller. Multiple fourth protrusion structures are formed in a ring shape at one end of the sealing plate facing the second impeller and are coaxially arranged with the second impeller. The multiple fourth protrusion structures are arranged at intervals along the radial direction of the second impeller. The plurality of third protrusions and the plurality of fourth protrusions are arranged alternately along the radial direction, and define a second sealing gap that meanders along the radial direction between the back of the second impeller and the sealing plate.

5. The compressor according to claim 4, characterized in that, Along the axial direction, the end face of the third protrusion structure facing the sealing plate is provided with at least two coaxially arranged third annular grooves. All the third annular grooves are arranged sequentially at intervals along the radial direction and divide the third protrusion structure into multiple third comb tooth structures. The third comb tooth structures extend outward in the radial direction relative to the axial direction. And / or, along the axial direction, the end face of the fourth protrusion structure facing the second impeller is provided with at least two coaxially arranged fourth annular grooves, all of the fourth annular grooves are arranged sequentially at intervals along the radial direction and the fourth protrusion structure is divided into a plurality of fourth comb tooth structures, the fourth comb tooth structures extending obliquely outward relative to the axial direction toward the radial direction.

6. The compressor according to claim 1, characterized in that, The first impeller includes an impeller body and a boss connected to each other. The back of the first impeller is located on the impeller body. Along the axial direction, one end of the boss away from the impeller body abuts against the back of the second impeller. The sealing plate is sleeved on the outside of the boss. A third sealing structure is formed between the circumferential outer wall of the boss and the circumferential inner wall of the sealing plate.

7. The compressor according to claim 6, characterized in that, The circumferential inner wall of the sealing plate is provided with a plurality of fifth comb tooth structures, which form the third sealing structure.

8. The compressor according to any one of claims 1 to 7, characterized in that, The sealing plate is a graphite sealing plate.

9. The compressor according to any one of claims 1 to 7, characterized in that, The compressor also includes: The second volute has a third inner cavity, and the second end of the rotating shaft is located in the third inner cavity; The third impeller is disposed in the third inner cavity and connected to the second end of the rotating shaft; A wheel back seal is provided, which is connected to the housing of the compressor and is disposed opposite to the back of the third impeller. A fourth sealing structure is provided between the wheel back seal and the back of the third impeller.

10. The compressor according to any one of claims 1 to 7, characterized in that, The sealing plate is detachably connected to the first volute.

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