Gas compression assembly for a centrifugal compressor and centrifugal compressor

Abstract

The application discloses a gas compression assembly for a centrifugal compressor and the centrifugal compressor, and relates to the technical field of compressors.The gas compression assembly comprises a motor, a primary compression wheel, a secondary compression wheel and a tertiary compression wheel.The motor has a rotor shaft, the primary compression wheel is fixed to the first end of the rotor shaft, the primary compression wheel nose is located on the side of the primary compression wheel back away from the motor, the secondary compression wheel is fixed to the second end of the rotor shaft, the secondary compression wheel back is located on the side of the secondary compression wheel nose away from the motor, the tertiary compression wheel is fixed to the second end of the rotor shaft and located on the side of the secondary compression wheel away from the motor, and the tertiary compression wheel nose is located on the side of the tertiary compression wheel back away from the motor.The gas compression assembly according to the application can realize self balance of the axial force of the gas compression assembly, is beneficial to improving the stability of the gas compression assembly during work, is beneficial to improving the reliability of the centrifugal compressor, can reduce gas leakage, and can improve the work efficiency of the gas compression assembly.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of compressors, in particular to a gas compression assembly for a centrifugal compressor and a centrifugal compressor with the same. BACKGROUND

[0002] In the related art, the gas compression assembly of the existing centrifugal compressor cannot achieve self-balance of the axial force, is subjected to high axial force, affects the reliability of the compressor, and the gas compression assembly is prone to gas leakage. SUMMARY

[0003] The present application aims to at least solve one of the technical problems in the prior art. To this end, one object of the present application is to provide a gas compression assembly for a centrifugal compressor, which can achieve self-balance of the axial force of the gas compression assembly, reduce the axial force, be conducive to improving the stability of the gas compression assembly during operation, be conducive to improving the reliability of the centrifugal compressor, can reduce gas leakage, and can improve the working efficiency of the gas compression assembly.

[0004] The present application further provides a centrifugal compressor using the above gas compression assembly.

[0005] According to the gas compression assembly for a centrifugal compressor of the first aspect of the present application, the gas compression assembly comprises a motor, a first-stage compression wheel, a second-stage compression wheel and a third-stage compression wheel, the motor has a rotor shaft, the first-stage compression wheel is fixed to a first end of the rotor shaft, the first-stage compression wheel has a first-stage compression wheel nose and a first-stage compression wheel back, the first-stage compression wheel nose is located on a side of the first-stage compression wheel back away from the motor, the second-stage compression wheel is fixed to a second end of the rotor shaft, the second-stage compression wheel has a second-stage compression wheel nose and a second-stage compression wheel back, the second-stage compression wheel back is located on a side of the second-stage compression wheel nose away from the motor, the second-stage compression wheel is used for compressing gas compressed by the first-stage compression wheel, the third-stage compression wheel is fixed to the second end of the rotor shaft and located on a side of the second-stage compression wheel back away from the motor, the third-stage compression wheel has a third-stage compression wheel nose and a third-stage compression wheel back, the third-stage compression wheel nose is located on a side of the third-stage compression wheel back away from the motor, and the third-stage compression wheel is used for compressing gas compressed by the second-stage compression wheel.

[0006] According to the gas compression assembly of the present application, the rotor shaft is subjected to a small stable axial force, the rotor shaft can stably rotate, the self-balance of the axial force of the gas compression assembly can be achieved, the axial force is reduced, the stability of the gas compression assembly during operation is improved, the reliability of the centrifugal compressor is improved, gas leakage is reduced, and the working efficiency of the gas compression assembly is improved.

[0007] According to some embodiments of the present application, the outer diameter of the back of the first compression wheel is D1, the outer diameter of the back of the second compression wheel is D2, and the outer diameter of the back of the third compression wheel is D3, and the following relationship is satisfied: D1:D2:D3=1:0.77:0.84.

[0008] According to some embodiments of the present application, the outer diameter of the nose of the first compression wheel is D4, and the following relationship is satisfied: 130mm≤D1≤134mm, 82mm≤D4≤86mm; the outer diameter of the nose of the second compression wheel is D5, and the following relationship is satisfied: 99mm≤D2≤102mm, 78mm≤D5≤82mm; the outer diameter of the nose of the third compression wheel is D6, and the following relationship is satisfied: 108mm≤D3≤112mm, 58mm≤D6≤62mm.

[0009] According to some embodiments of the present application, the first and second compression wheels are closed impellers, and the third compression wheel is an open impeller.

[0010] According to some embodiments of the present application, the gas pressure inside the motor is higher than the gas pressure at the back of the first compression wheel, and the gas pressure inside the motor is higher than the gas pressure at the nose of the second compression wheel.

[0011] According to some embodiments of the present application, the motor further comprises an outer housing and a stator, the outer housing defines a mounting cavity, the stator is arranged in the mounting cavity and fixed to a shell side wall of the outer housing, the rotor shaft is rotatably arranged in and penetrates through the outer housing, the shell side wall is formed with a wire outlet hole in communication with the mounting cavity, the wire outlet hole is located at an end of the shell side wall away from the first compression wheel, and an electric connection wire of the stator is arranged in the wire outlet hole.

[0012] According to some embodiments of the present application, the motor further comprises an outer housing, the outer housing has a mounting seat opposite to the second compression wheel, the rotor shaft penetrates through the mounting seat and is rotatable relative to the mounting seat, and a surface of the mounting seat facing the second compression wheel is formed with a flow guide structure configured to guide the gas compressed by the first compression wheel to the second compression wheel.

[0013] According to some embodiments of the present application, the motor further comprises an outer housing, and a cooling flow channel is formed in a shell side wall of the outer housing, and a heat dissipation structure is formed on an inner surface of the cooling flow channel.

[0014] According to some embodiments of the present application, the gas compression assembly for the centrifugal compressor further comprises a partition plate sleeved on the rotor shaft and located between the second compression wheel and the third compression wheel, so as to separate the second compression wheel and the third compression wheel.

[0015] The centrifugal compressor according to the second aspect of the embodiments of the present application comprises the gas compression assembly as described in the above embodiments.

[0016] Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and / or can be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0017] The foregoing and / or additional aspects and advantages of the present application are achieved by providing what is described below and / or claimed herein.

[0018] Figure 1 is a sectional view of a gas compression assembly according to embodiments of the present application;

[0019] Figure 2 is Figure 1 is a partial enlarged view of region A in FIG. 4;

[0020] Figure 3 is Figure 1 is a partial enlarged view of region B in FIG. 4.

[0021] REFERENCE NUMERALS:

[0022] a gas compression assembly 1,

[0023] a motor 10, a rotor shaft 11, a weight-reducing space 111, an outer housing 12, a mounting cavity 121, a shell side wall 122, a wire outlet hole 1221, a cooling flow channel 1222, an inner side wall 1223, an outer side wall 1224, a mounting seat 123, a flow guide structure 1231, a mounting through hole 1232, a sealing groove body 1233, a second abutting surface 1234, a stator 13, an electrical connection wire 131, a first air radial bearing 14, a second air radial bearing 15,

[0024] a primary compression wheel 20, a primary compression wheel nose 21, a primary compression wheel back 22, a first assembly hole 23, a first mounting hole 24,

[0025] a secondary compression wheel 30, a secondary compression wheel nose 31, a secondary compression wheel back 32, a first mounting groove 321, a second assembly hole 33,

[0026] a tertiary compression wheel 40, a tertiary compression wheel nose 41, a tertiary compression wheel back 42, a second mounting groove 421, a third assembly hole 43, a second mounting hole 44,

[0027] a shaft seal 50, a sealing boss 51, a first abutting surface 52,

[0028] a gas flow channel 60,

[0029] an air thrust bearing 70, a thrust disc 71,

[0030] The back plate 80, the third through hole 81,

[0031] The end wall 90, the second through hole 91. DETAILED DESCRIPTION

[0032] Embodiments of the present application are described below in detail, examples of which are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary, only for explaining the present application, and cannot be understood as a limitation of the present application.

[0033] The following description is made with reference to the accompanying drawings, Figures 1-3 A gas compression assembly 1 for a centrifugal compressor according to an embodiment of the present application is described below, which can be installed on a centrifugal compressor.

[0034] The gas compression assembly 1 for a centrifugal compressor according to an embodiment of the first aspect of the present application, as shown in Figure 1 and Figure 2 The gas compression assembly 1 can include a motor 10, a primary impeller 20, a secondary impeller 30 and a tertiary impeller 40, the motor 10 having a rotor shaft 11, the primary impeller 20 being fixed to a first end of the rotor shaft 11, the primary impeller 20 having a primary impeller nose 21 and a primary impeller back 22, the primary impeller nose 21 being located on a side of the primary impeller back 22 away from the motor 10, the secondary impeller 30 being fixed to a second end of the rotor shaft 11, the secondary impeller 30 having a secondary impeller nose 31 and a secondary impeller back 32, the secondary impeller back 32 being located on a side of the secondary impeller nose 31 away from the motor 10, the secondary impeller 30 being used to compress gas compressed by the primary impeller 20, the tertiary impeller 40 being fixed to the second end of the rotor shaft 11 and located on a side of the secondary impeller 30 away from the motor 10, the tertiary impeller 40 having a tertiary impeller nose 41 and a tertiary impeller back 42, the tertiary impeller nose 41 being located on a side of the tertiary impeller back 42 away from the motor 10, the tertiary impeller 40 being used to compress gas compressed by the secondary impeller 30.

[0035] It should be noted that in the related art, the gas compression assembly of the existing centrifugal compressor cannot achieve self-balance of the axial force, the axial force received is high, which affects the reliability of the compressor, and the gas compression assembly is prone to gas leakage.

[0036] Based on this, the embodiments of the present application propose a gas compression assembly 1 for a centrifugal compressor, the motor 10 has a rotor shaft 11, the rotor shaft 11 can extend in a first direction, when the gas compression assembly 1 is arranged as Figure 1 The first direction can be Figure 1The first direction can be parallel to the axial direction of the rotor shaft 11. The rotor shaft 11 can be made of a magnetic steel material. The rotor shaft 11 can be formed with a weight-reducing space 111. By arranging the rotor shaft 11 as a hollow shaft, the weight of the rotor shaft 11 can be reduced, the cost can be reduced, the modal frequency of the rotor shaft 11 can be improved, the risk of vibration of the rotor shaft 11 during rotation can be reduced, and the weight of the gas compression assembly 1 can be reduced.

[0037] The rotor shaft 11 can be connected with the first compression wheel 20, the second compression wheel 30, and the third compression wheel 40. The rotor shaft 11 can drive the first compression wheel 20, the second compression wheel 30, and the third compression wheel 40 to rotate together. When the first compression wheel 20 rotates, the first compression wheel 20 can compress the gas in the first compression wheel 20. When the second compression wheel 30 rotates, the second compression wheel 30 can compress the gas in the second compression wheel 30. When the third compression wheel 40 rotates, the third compression wheel 40 can compress the gas in the third compression wheel 40. The first compression wheel 20 can be fixed to the first end of the rotor shaft 11. The first compression wheel 20 can be fixedly connected with the rotor shaft 11 by clamping, bolt connection, or the like. The first compression wheel 20 has a first compression wheel nose 21 and a first compression wheel back 22. When the first compression wheel 20 is assembled with the rotor shaft 11, the first compression wheel nose 21 and the first compression wheel back 22 can be oppositely arranged and spaced apart along the first direction. The first compression wheel back 22 is located on the side of the first compression wheel 20 facing the motor 10. The first compression wheel nose 21 is located on the side of the first compression wheel back 22 away from the motor 10.

[0038] As an example, the first compression wheel 20 can be fixedly connected with the rotor shaft 11 by a bolt. The first compression wheel 20 can be formed with a first assembly hole 23 located on the side of the first compression wheel 20 facing the motor 10. The rotor shaft 11 can extend into the first assembly hole 23 and abut against the inner wall of the first assembly hole 23, so that the first compression wheel 20 can be sleeved on the rotor shaft 11. The first compression wheel 20 can be formed with a first mounting hole 24 penetrating the first compression wheel 20 along the first direction. The first mounting hole 24 and the first assembly hole 23 are oppositely arranged and communicated along the first direction. When the first compression wheel 20 is sleeved on the rotor shaft 11, a fixing bolt can be arranged in the first mounting hole 24, the first assembly hole 23, and assembled with the rotor shaft 11, so that the first compression wheel 20 and the rotor shaft 11 are fixedly connected, and the rotor shaft 11 can drive the first compression wheel 20 to rotate together.

[0039] The second-stage compression wheel 30 can be fixedly arranged at the second end of the rotor shaft 11, and can be fixedly connected with the rotor shaft 11 by clamping, bolt connection or the like. The second-stage compression wheel 30 has a second-stage compression wheel nose 31 and a second-stage compression wheel back 32. When the second-stage compression wheel 30 is assembled with the rotor shaft 11, the second-stage compression wheel nose 31 and the second-stage compression wheel back 32 can be oppositely arranged and spaced apart along the first direction. The second-stage compression wheel nose 31 is located at the side of the second-stage compression wheel 30 facing the motor 10, and the second-stage compression wheel back 32 is located at the side of the second-stage compression wheel nose 31 away from the motor 10. The gas compressed by the first-stage compression wheel 20 can flow to the second-stage compression wheel 30, and the second-stage compression wheel 30 can be used to compress the gas compressed by the first-stage compression wheel 20. The pressure value of the gas compressed by the second-stage compression wheel 30 is higher than that of the gas compressed by the first-stage compression wheel 20.

[0040] The third-stage compression wheel 40 can be fixedly arranged at the second end of the rotor shaft 11, and can be fixedly connected with the rotor shaft 11 by clamping, bolt connection or the like. The third-stage compression wheel 40 can be located at the side of the second-stage compression wheel 30 away from the motor 10. The third-stage compression wheel 40 has a third-stage compression wheel nose 41 and a third-stage compression wheel back 42. When the third-stage compression wheel 40 is assembled with the rotor shaft 11, the third-stage compression wheel nose 41 and the third-stage compression wheel back 42 can be oppositely arranged and spaced apart along the first direction. The third-stage compression wheel back 42 is located at the side of the third-stage compression wheel 40 facing the motor 10, and the third-stage compression wheel nose 41 is located at the side of the third-stage compression wheel back 42 away from the motor 10. The gas compressed by the second-stage compression wheel 30 can flow to the third-stage compression wheel 40, and the third-stage compression wheel 40 can be used to compress the gas compressed by the second-stage compression wheel 30. The pressure value of the gas compressed by the third-stage compression wheel 40 is higher than that of the gas compressed by the second-stage compression wheel 30.

[0041] As an example, as Figure 2As shown, the secondary compression roller 30 can be sleeved on the rotor shaft 11, and the tertiary compression roller 40 can be fixedly connected with the rotor shaft 11 through bolts. The secondary compression roller 30 can be clamped between the tertiary compression roller 40 and the motor 10. The secondary compression roller 30 can be formed with a second assembly hole 33 penetrating the secondary compression roller 30 in the first direction, and the rotor shaft 11 can be arranged in the second assembly hole 33 and abut against the inner wall of the second assembly hole 33, so that the secondary compression roller 30 can be sleeved on the rotor shaft 11. The tertiary compression roller 40 can be formed with a third assembly hole 43 located on the side of the tertiary compression roller 40 facing the motor 10, and the rotor shaft 11 can extend into the third assembly hole 43 and abut against the inner wall of the third assembly hole 43, so that the tertiary compression roller 40 can be sleeved on the rotor shaft 11. The tertiary compression roller 40 can be formed with a second mounting hole 44 penetrating the tertiary compression roller 40 in the first direction, and the second mounting hole 44 and the third assembly hole 43 can be oppositely arranged and communicated in the first direction. When the tertiary compression roller 40 is sleeved on the rotor shaft 11, the fixing bolts can be arranged in the second mounting hole 44 and assembled with the rotor shaft 11, so that the tertiary compression roller 40 and the rotor shaft 11 are fixedly connected, and the secondary compression roller 30 is clamped between the tertiary compression roller 40 and the motor 10, thereby realizing the effect that the rotor shaft 11 drives the secondary compression roller 30 and the tertiary compression roller 40 to rotate together.

[0042] When the gas enters the gas compression assembly 1, the gas can be compressed in the primary compression roller 20 first. The gas compressed by the primary compression roller 20 flows to the secondary compression roller 30, and the secondary compression roller 30 compresses the gas compressed by the primary compression roller 20 to increase the pressure of the gas. The gas compressed by the secondary compression roller 30 flows to the tertiary compression roller 40, and the tertiary compression roller 40 compresses the gas compressed by the secondary compression roller 30 to further increase the pressure of the gas. The gas compression assembly 1 can realize the step-by-step compression of the gas, so that the centrifugal compressor can realize a higher pressure ratio. Moreover, the rotor shaft 11 is formed with a weight-reducing space 111, which is beneficial to reducing the weight of the gas compression assembly 1.

[0043] The first-stage compression wheel back 22 is arranged towards the motor 10, the second-stage compression wheel nose 31 is arranged towards the motor 10, the second-stage compression wheel back 32 and the third-stage compression wheel back 42 are arranged adjacently, and the first-stage compression wheel 20, the second-stage compression wheel 30 and the third-stage compression wheel 40 are connected in series, so that multi-stage compression of the gas can be realized. The gas compressed by the first-stage compression wheel 10 can be further compressed by the second-stage compression wheel 30, and the gas flowing out of the first-stage compression wheel back 22 can flow into the second-stage compression wheel nose 31. The gas pressure at the first-stage compression wheel back 22 is less than the gas pressure at the third-stage compression wheel back 42, and the gas pressure at the second-stage compression wheel nose 31 is less than the gas pressure at the third-stage compression wheel back 42. The first-stage compression wheel back 22 and the second-stage compression wheel nose 31 are respectively located on two sides of the motor 10 along the first direction, so that the pressure on both sides of the motor 10 is relatively small, the pressure difference between the motor 10 and the first-stage compression wheel 20 can be reduced, the pressure difference between the motor 10 and the second-stage compression wheel 30 can be reduced, the probability of gas leakage between the motor 10 and the first-stage compression wheel 20 and the second-stage compression wheel 30 can be reduced, gas leakage can be reduced, and the working efficiency of the gas compression assembly 1 can be improved.

[0044] In the embodiments of the present application, the first-stage compression wheel 20 can be one of an open impeller and a closed impeller, the second-stage compression wheel 30 can be one of an open impeller and a closed impeller, and the third-stage compression wheel 40 can be one of an open impeller and a closed impeller. When designing the structure of the gas compression assembly 1, different types of impellers can be selected according to the orientations of the first-stage compression wheel 20, the second-stage compression wheel 30 and the third-stage compression wheel 40. As an example, the first-stage compression wheel 20 and the second-stage compression wheel 30 can be closed impellers, and the third-stage compression wheel 40 can be an open impeller. The first-stage compression wheel back 22 is arranged towards the motor 10, the second-stage compression wheel nose 31 is arranged towards the motor 10, and the second-stage compression wheel back 32 and the third-stage compression wheel back 42 are arranged adjacently, so that the rotor shaft 11 can be subjected to a relatively small stable axial force, the rotor shaft 11 can be stably rotated, the self-balance of the axial force of the gas compression assembly 1 can be realized, the axial force is reduced, the stability of the gas compression assembly 1 during operation is improved, and the reliability of the centrifugal compressor is improved.

[0045] As an example, the outer surface of the head of the fixing bolt is configured as an arc surface, which can be a semicircular structure. When the compressed gas flows through the fixing bolt, the probability that the fixing bolt hinders the flow of the gas can be reduced, and the working efficiency of the gas compression assembly 1 is improved.

[0046] In some embodiments of the present application, the outer diameter of the first-stage compression wheel back 22 is D1, the outer diameter of the second-stage compression wheel back 32 is D2, and the outer diameter of the third-stage compression wheel back 42 is D3, and the relationship D1:D2:D3 is 1:0.77:0.84.

[0047] Exemplarily, the outer diameter size of the primary compression wheel back 22 can be D1, the outer diameter size of the secondary compression wheel back 32 can be 0.77D1, and the outer diameter size of the tertiary compression wheel back 42 can be 0.84D1. The outer diameter sizes of the primary compression wheel back 22, the secondary compression wheel back 32, and the tertiary compression wheel back 42 are in the same proportion, and the outer diameter size of the secondary compression wheel back 32 is 0.77 times the outer diameter size of the primary compression wheel back 22, and the outer diameter size of the tertiary compression wheel back 42 is 0.84 times the outer diameter size of the primary compression wheel back 22. If D1:D2:D3 does not satisfy 1:0.77:0.84, the total axial force on the gas compression assembly 1 will be affected, the stable rotation of the rotor shaft 11 will be affected, the centrifugal compressor cannot realize self-balance of the axial force, the stability of the gas compression assembly 1 during operation will be affected, and the reliability of the centrifugal compressor will be affected.

[0048] In some embodiments of the present application, the outer diameter size of the primary compression wheel nose 21 is D4, which satisfies the relationship: 130mm≤D1≤134mm, 82mm≤D4≤86mm; the outer diameter size of the secondary compression wheel nose 31 is D5, which satisfies the relationship: 99mm≤D2≤102mm, 78mm≤D5≤82mm; and the outer diameter size of the tertiary compression wheel nose 41 is D6, which satisfies the relationship: 108mm≤D3≤112mm, 58mm≤D6≤62mm.

[0049] Exemplarily, the outer diameter size of the primary compression wheel back 22 can be 130mm, 132mm, 133.2mm, 134mm, etc., and the outer diameter size of the primary compression wheel back 22 can be in the range of 130mm to 134mm, including any value within the range, which is the outer diameter size of the primary compression wheel back 22 in the present application. If the outer diameter size of the primary compression wheel back 22 is less than 130mm, the axial force on the primary compression wheel back 22 will decrease, and if the outer diameter size of the primary compression wheel back 22 is greater than 134mm, the axial force on the primary compression wheel back 22 will increase. If the axial force on the primary compression wheel back 22 in the gas compression assembly 1 changes alone, the self-balance of the axial force of the gas compression assembly 1 will be affected, and the reliability of the centrifugal compressor will be affected.

[0050] Exemplarily, the outer diameter of the primary compression wheel nose 21 can be 82mm, 83mm, 84mm, 84.7mm, 86mm, etc. The outer diameter of the primary compression wheel nose 21 can be in the range of 82mm to 86mm, including any value between the endpoints, which are all optional outer diameters of the primary compression wheel nose 21. If the outer diameter of the primary compression wheel nose 21 is less than 82mm, the axial force on the primary compression wheel nose 21 will decrease, and if the outer diameter of the primary compression wheel nose 21 is greater than 86mm, the axial force on the primary compression wheel nose 21 will increase. If the axial force on the primary compression wheel nose 21 in the gas compression assembly 1 changes alone, it will affect the self-balance of the axial force of the gas compression assembly 1 and affect the reliability of the centrifugal compressor.

[0051] Exemplarily, the outer diameter of the secondary compression wheel back 32 can be 99mm, 100mm, 101.6mm, 102mm, etc. The outer diameter of the secondary compression wheel back 32 can be in the range of 99mm to 102mm, including any value between the endpoints, which are all optional outer diameters of the secondary compression wheel back 32. If the outer diameter of the secondary compression wheel back 32 is less than 99mm, the axial force on the secondary compression wheel back 32 will decrease, and if the outer diameter of the secondary compression wheel back 32 is greater than 102mm, the axial force on the secondary compression wheel back 32 will increase. If the axial force on the secondary compression wheel back 32 in the gas compression assembly 1 changes alone, it will affect the self-balance of the axial force of the gas compression assembly 1 and affect the reliability of the centrifugal compressor.

[0052] Exemplarily, the outer diameter of the secondary compression wheel nose 31 can be 78mm, 79mm, 80mm, 81.5mm, 82mm, etc. The outer diameter of the secondary compression wheel nose 31 can be in the range of 78mm to 82mm, including any value between the endpoints, which are all optional outer diameters of the secondary compression wheel nose 31. If the outer diameter of the secondary compression wheel nose 31 is less than 78mm, the axial force on the secondary compression wheel nose 31 will decrease, and if the outer diameter of the secondary compression wheel nose 31 is greater than 82mm, the axial force on the secondary compression wheel nose 31 will increase. If the axial force on the secondary compression wheel nose 31 in the gas compression assembly 1 changes alone, it will affect the self-balance of the axial force of the gas compression assembly 1 and affect the reliability of the centrifugal compressor.

[0053] Exemplarily, the outer diameter size of the tertiary pressure roller back 42 can be 108 mm, 109.5 mm, 110.8 mm, 112 mm, etc., and the outer diameter size of the tertiary pressure roller back 42 can be in the range of 108 mm to 112 mm, including any value at the endpoint, which is the outer diameter size of the optional tertiary pressure roller back 42 of the present application. If the outer diameter size of the tertiary pressure roller back 42 is less than 108 mm, the axial force on the tertiary pressure roller back 42 will decrease, and if the outer diameter size of the tertiary pressure roller back 42 is greater than 112 mm, the axial force on the tertiary pressure roller back 42 will increase. If the axial force on the tertiary pressure roller back 42 in the gas compression assembly 1 changes alone, it will affect the self-balance of the axial force of the gas compression assembly 1 and affect the reliability of the centrifugal compressor.

[0054] Exemplarily, the outer diameter size of the tertiary pressure roller back 42 can be 108 mm, 109.5 mm, 110.8 mm, 112 mm, etc., and the outer diameter size of the tertiary pressure roller back 42 can be in the range of 108 mm to 112 mm, including any value at the endpoint, which is the outer diameter size of the optional tertiary pressure roller back 42 of the present application. If the outer diameter size of the tertiary pressure roller back 42 is less than 108 mm, the axial force on the tertiary pressure roller back 42 will decrease, and if the outer diameter size of the tertiary pressure roller back 42 is greater than 112 mm, the axial force on the tertiary pressure roller back 42 will increase. If the axial force on the tertiary pressure roller back 42 in the gas compression assembly 1 changes alone, it will affect the self-balance of the axial force of the gas compression assembly 1 and affect the reliability of the centrifugal compressor.

[0055] Therefore, the outer diameter size of the primary pressure roller back 22 is between 130 mm and 134 mm, the outer diameter size of the primary pressure roller nose 21 is between 82 mm and 86 mm, the outer diameter size of the secondary pressure roller back 32 is between 99 mm and 102 mm, the outer diameter size of the secondary pressure roller nose 31 is between 78 mm and 82 mm, the outer diameter size of the tertiary pressure roller back 42 is between 108 mm and 112 mm, and the outer diameter size of the tertiary pressure roller nose 41 is between 58 mm and 62 mm, which can make the rotor shaft 11 receive stable and small axial force, and the gas compression assembly 1 can achieve self-balance of the axial force.

[0056] In practical applications, the outer diameter of the first-stage pressure roller nose 21, the outer diameter of the second-stage pressure roller nose 31, and the outer diameter of the third-stage pressure roller nose 41 are small in size, and the outer diameter of the first-stage pressure roller nose 21, the outer diameter of the second-stage pressure roller back 32, and the outer diameter of the third-stage pressure roller back 42 can be increased or decreased at the same time, so that the outer diameter of the first-stage pressure roller back 22, the outer diameter of the second-stage pressure roller back 32, and the outer diameter of the third-stage pressure roller back 42 always satisfy the relationship D1:D2:D3=1:0.77:0.84, thereby reducing the probability that the size of the first-stage pressure roller 20, the second-stage pressure roller 30, and the third-stage pressure roller 40 affects the axial force of the gas compression assembly 1.

[0057] In some embodiments of the present application, the first-stage pressure roller 20 and the second-stage pressure roller 30 are closed impellers, and the third-stage pressure roller 40 is an open impeller.

[0058] The open impeller and the closed impeller are two different types of impeller structures, the blades of the open impeller are open, and the blades of the closed impeller are closed, and the outer edge of the blades of the closed impeller is covered with a wheel cover. When the open impeller and the closed impeller are connected in series, the blade part axial forces received by the open impeller and the closed impeller are different, the blade part axial force received by the open impeller can be the average of the impeller inlet pressure and the impeller outlet pressure, and the blade part axial force received by the closed impeller can be 0.8-0.9 times the impeller outlet pressure, so the blade part axial force of the closed impeller is usually larger than the blade part axial force of the open impeller. The total axial force of a single closed impeller usually points to the back, and the total axial force of a single open impeller usually points to the nose.

[0059] By setting the first-stage pressure roller 20 and the second-stage pressure roller 30 as closed impellers, the third-stage pressure roller 40 as an open impeller, the first-stage pressure roller back 22 towards the motor 10, the second-stage pressure roller nose 31 towards the motor 10, and the third-stage pressure roller back 42 towards the motor 10, that is, the orientation of the first-stage pressure roller 20 is the same as the orientation of the second-stage pressure roller 30, the orientation of the third-stage pressure roller 40 is opposite to the orientation of the first-stage pressure roller 20 and the orientation of the second-stage pressure roller 30, and the outer diameter of the first-stage pressure roller back 22: the outer diameter of the second-stage pressure roller back 32: the outer diameter of the third-stage pressure roller back 42 is 1:0.77:0.84, the axial force of the gas compression assembly 1 can be balanced by itself, the rotor shaft 11 receives a smaller stable axial force, which is conducive to improving the stability of the gas compression assembly 1 during operation, and is conducive to improving the reliability of the centrifugal compressor.

[0060] As an example, the outer diameter of the first-stage impeller nose 21 can be 84 mm, the outer diameter of the first-stage impeller back 22 can be 132 mm, the outer diameter of the second-stage impeller nose 31 can be 80 mm, the outer diameter of the second-stage impeller back 32 can be 101.6 mm, the outer diameter of the third-stage impeller nose 41 can be 59.6 mm, and the outer diameter of the third-stage impeller back 42 can be 110.8 mm. The first-stage impeller 20 and the second-stage impeller 30 are closed impellers, while the third-stage impeller 40 is an open impeller. The axial force on the first-stage impeller nose 21 can be -590 N, the axial component force on the blade portion of the first-stage impeller 20 can be -2767 N, the axial force on the first-stage impeller back 22 can be 3894 N, and the total axial force on the first-stage impeller 20 can be 537 N. The axial force on the nose 31 of the second-stage pressure roller is -1761N, the axial component of the blade portion of the second-stage pressure roller 30 is -2578N, the axial force on the back 32 of the second-stage pressure roller is 5642N, and the total axial force on the second-stage pressure roller 30 is 1303N. The axial force on the nose 41 of the third-stage pressure roller is 2875N, the axial component of the blade portion of the third-stage pressure roller 40 is 9846N, the axial force on the back 42 of the third-stage pressure roller is -14604N, and the total axial force on the third-stage pressure roller 40 is -1883N. The total axial force on the gas compression assembly 1 is -43N, meaning the gas compression assembly 1 experiences a smaller axial force towards the second end of the rotor shaft 11.

[0061] It should be noted that the direction along the first direction, toward the first end of the rotor shaft 11, is the positive direction.

[0062] In some embodiments of the present invention, the gas pressure inside the motor 10 is higher than the gas pressure at the back 22 of the first-stage pressure roller, and the gas pressure inside the motor 10 is higher than the gas pressure at the nose 31 of the second-stage pressure roller.

[0063] The pressure difference between the inside of the motor 10 and the gas pressure at the back 22 of the first-stage pressure roller is small, and the pressure difference between the inside of the motor 10 and the gas pressure at the nose 31 of the second-stage pressure roller is also small. By setting the gas pressure inside the motor 10 to be higher than the gas pressure at the back 22 of the first-stage pressure roller and higher than the gas pressure at the nose 31 of the second-stage pressure roller, the probability of some gas leaking from the first-stage pressure roller 20 and the second-stage pressure roller 30 into the motor 10 can be reduced, thus reducing gas loss. If gas leaks from the inside of the motor 10 into the back 22 of the first-stage pressure roller and the nose 31 of the second-stage pressure roller, the leaked gas can be compressed within the first-stage pressure roller 20 and the second-stage pressure roller 30, enabling gas recovery and utilization, which is beneficial for reducing gas loss and improving the working efficiency of the gas compression assembly 1.

[0064] In some embodiments of the present invention, such as Figure 1As shown, the motor 10 also has a housing 12 and a stator 13. The housing 12 defines a mounting cavity 121. The stator 13 is disposed in the mounting cavity 121 and fixed to the housing side wall 122 of the housing 12. The rotor shaft 11 is rotatably disposed in the housing 12 and passes through the housing 12. The housing side wall 122 forms a wire outlet hole 1221 that communicates with the mounting cavity 121. The wire outlet hole 1221 is located at the end of the housing side wall 122 away from the first stage pressure roller 20. The electrical connection wire of the stator 13 is installed in the wire outlet hole 1221.

[0065] The outer casing 12 defines a mounting cavity 121. The stator 13 is located within the mounting cavity 121 and can be fixedly connected to the side wall 122 of the outer casing 12 by bolts, snap-fit, or other means. The stator 13 can be sleeved on the rotor shaft 11, allowing the rotor shaft 11 to rotate relative to the stator 13. At least a portion of the rotor shaft 11 is located within the mounting cavity 121 and passes through the outer casing 12, allowing it to rotate relative to the outer casing 12. The stator 13 can be constructed as a coil and can be connected to an electrical connection wire 131. When the stator 13 is energized, a rotating magnetic field is generated inside the motor 10. The rotor shaft 11 can be made of magnet steel, and a hollow magnetically conductive mandrel can be installed in the weight-reduction space 111 of the rotor shaft 11. When the stator 13 is energized, a magnetic field is generated within the mounting cavity 121, and the mandrel can drive the rotor shaft 11 to rotate according to the direction of the magnetic field, thereby achieving the effect of driving the rotor shaft 11 to rotate.

[0066] The housing sidewall 122 can have a cable outlet hole 1221, which can communicate with the mounting cavity 121. The electrical connection wire 131 of the stator 13 can be installed in the cable outlet hole 1221, and the electrical connection wire 131 can pass through the cable outlet hole 1221 and be connected to the power supply, thereby achieving the effect of energizing the stator 13. The housing sidewall 122 of the housing body 12 can have a gas flow channel 60. When the gas compressed by the first-stage pressure roller 20 flows out of the first-stage pressure roller 20, the gas compressed by the first-stage pressure roller 20 can flow through the gas flow channel 60 to the end of the motor 10 near the second-stage pressure roller 30, so that the gas compressed by the first-stage pressure roller 20 can flow into the second-stage pressure roller 30. The cable outlet hole 1221 can be located at the end of the housing sidewall 122 away from the first-stage pressure roller 20, which can reduce the probability that the cable outlet hole 1221 affects the flow rate of the gas compressed by the first-stage pressure roller 20, reduce energy loss, and help improve the working efficiency of the gas compression assembly 1. In other words, the gas that has just been compressed by the first-stage pressure roller 20 has a high flow rate. If the outlet hole 1221 is located at the end of the shell sidewall 122 near the first-stage pressure roller 20, the outlet hole 1221 will obstruct the flow of the gas that has just flowed out of the first-stage pressure roller 20, resulting in energy loss.

[0067] As an example, a flow guiding component can be provided within the gas flow channel 60. This component can be located on the inner wall of the gas flow channel 60. The flow guiding component can guide the gas compressed by the primary pressure roller 20 towards the end of the shell sidewall 122 near the secondary pressure roller 30, ensuring stable gas flow. When the gas flows through the outlet hole 1221, the gas flow rate is not affected, which helps reduce energy loss. The flow guiding component can be constructed as a guide boss protruding from the inner wall of the gas flow channel 60. Multiple guide bosses can be present, allowing the gas within the gas flow channel 60 to be diverted and guided to the end of the shell sidewall 122 near the secondary pressure roller 30.

[0068] In some embodiments of the present invention, such as Figure 1 As shown, the motor 10 also has a housing 12, which has a mounting base 123 opposite to the secondary pressure roller 30. The rotor shaft 11 passes through the mounting base 123 and is rotatable relative to the mounting base 123. A flow guiding structure 1231 is formed on the surface of the mounting base 123 facing the secondary pressure roller 30. The flow guiding structure 1231 is configured to guide the gas compressed by the primary pressure roller 20 to the secondary pressure roller 30.

[0069] Along the first direction, the outer casing 12 has a mounting seat 123 opposite to the secondary pressure roller 30. The mounting seat 123 can be assembled with the shell sidewall 122 of the outer casing 12. The mounting seat 123 can be fixedly connected to the shell sidewall 122 by means of snap-fit, bolt connection, etc. The mounting seat 123 and the shell sidewall 122 can jointly define the mounting cavity 121. The mounting seat 123 can be formed with a first through hole, which can penetrate the mounting seat 123 along the thickness direction. The rotor shaft 11 can pass through the first through hole and can rotate relative to the mounting seat 123. As an example, a first air radial bearing 14 can be sleeved on the shaft section of the rotor shaft 11 near the second end. The first air radial bearing 14 can be installed in the first through hole and can be fixedly connected to the mounting seat 123 by bolts, positioning pins, etc. When the rotor shaft 11 rotates, the rotor shaft 11 can rotate relative to the first air radial bearing 14, thereby allowing the rotor shaft 11 to rotate relative to the mounting seat 123.

[0070] The mounting base 123 can be arranged adjacent to the outlet of the gas flow channel 60. The gas compressed by the first-stage pressure roller 20 flowing in the gas flow channel 60 can flow to the surface of the mounting base 123 facing the second-stage pressure roller 30. A flow guiding structure 1231 can be formed on the surface of the mounting base 123 facing the second-stage pressure roller 30. The flow guiding structure 1231 can guide the gas compressed by the first-stage pressure roller 20 to the second-stage pressure roller 30. In other words, the flow guiding structure 1231 can guide the gas flowing out of the gas flow channel 60 to the second-stage pressure roller 30, so that the gas compressed by the first-stage pressure roller 20 can flow into the second-stage pressure roller 30, which is beneficial to improving the efficiency of the gas compressed by the first-stage pressure roller 20 flowing into the second-stage pressure roller 30, and making the gas compressed by the first-stage pressure roller 20 compressible in the second-stage pressure roller 30.

[0071] In some embodiments of the present invention, the flow guiding structure 1231 may include a plurality of flow guiding blades, which are arranged around the rotor shaft 11 along the circumference of the mounting base 123.

[0072] The flow guiding structure 1231 may include multiple flow guiding blades, which can be arranged circumferentially along the mounting base 123, and each flow guiding blade can extend radially along the mounting base 123. When the rotor shaft 11 passes through the mounting base 123, the multiple flow guiding blades can be arranged around the rotor shaft 11, and the secondary pressure roller 30 is sleeved on the rotor shaft 11. The multiple flow guiding blades can divert the gas compressed by the primary pressure roller 20 and guide the gas compressed by the primary pressure roller 20 to the secondary pressure roller 30, thereby improving the efficiency of the gas compressed by the primary pressure roller 20 flowing into the secondary pressure roller 30, which is beneficial to improving the working efficiency of the gas compression assembly 1.

[0073] In some embodiments of the present invention, the motor 10 further includes a housing 12, wherein a cooling channel 1222 is formed in the housing sidewall 122 of the housing 12, and a heat dissipation structure is formed on the inner surface of the cooling channel 1222.

[0074] The motor 10 also has a housing 12, and a cooling channel 1222 is formed within the housing sidewall 122 of the housing 12. The cooling channel 1222 can be arranged around the mounting cavity 121, and cooling gas can flow within the cooling channel 1222. The cooling gas can be used to cool the motor 10, and the cooling gas can exchange heat with the inner surface of the cooling channel 1222. A heat dissipation structure can be formed on the inner surface of the cooling channel 1222. The heat dissipation structure can be constructed as a serrated structure protruding from the inner surface of the cooling channel 1222. By setting the heat dissipation structure, the contact area between the cooling gas and the cooling channel 1222 can be increased, which is beneficial to improving the heat dissipation efficiency of the motor 10.

[0075] As an example, the cooling channel 1222 can be connected to the mounting cavity 121, and the cooling gas in the cooling channel 1222 can flow into the mounting cavity 121. The cooling gas can cool part of the stator 13 and rotor shaft 11 in the mounting cavity 121, thereby achieving the effect of further cooling the motor 10, which is beneficial to improving the heat dissipation performance of the gas compression assembly 1.

[0076] In some embodiments of the present invention, such as Figure 1 As shown, the shell sidewall 122 may include an inner sidewall 1223 and an outer sidewall 1224. The outer sidewall 1224 is sleeved on the outside of the inner sidewall 1223 and is detachably connected to the inner sidewall 1223. A first groove is formed on the surface of the outer sidewall 1224 facing the inner sidewall 1223, and a second groove is formed on the surface of the inner sidewall 1223 facing the outer sidewall 1224. The first groove and the second groove are opposite to each other to define a cooling channel 1222.

[0077] Along the radial direction of the outer casing 12, the outer sidewall 1224 can be fitted onto the outer sidewall 1223. The outer sidewall 1224 can be connected to the inner sidewall 1223 by means of snap-fit, bolt connection, etc., and the outer sidewall 1224 and the inner sidewall 1223 are detachably connected. A first groove is formed on the surface of the outer sidewall 1224 facing the inner sidewall 1223, and the first groove is recessed inward toward the outer sidewall 1224. A second groove is formed on the surface of the inner sidewall 1223 facing the outer sidewall 1224, and the second groove is recessed inward toward the inner sidewall 1223. The first groove and the second groove can be arranged opposite to each other, and the first groove and the second groove can together define a cooling channel 1222, in which cooling gas can flow. By setting the outer sidewall 1224 and the inner sidewall 1223 to be detachably connected, it is convenient to process the heat dissipation structure on the inner surface of the cooling channel 1222, which helps to reduce production costs.

[0078] In some embodiments of the present invention, such as Figure 1 and Figure 3As shown, the gas compression assembly 1 for the centrifugal compressor may further include: a shaft seal 50; the motor 10 also has a housing 12, the housing 12 having a mounting seat 123 opposite to the secondary pressure roller 30; the mounting seat 123 having a mounting through hole 1232; the rotor shaft 11 passing through the mounting through hole 1232 and rotatable relative to the mounting seat 123; the shaft seal 50 being sleeved on the rotor shaft 11 and mounted in the mounting through hole 1232; one of a sealing boss 51 and a sealing groove 1233 being formed on the outer side wall of the shaft seal 50; the other of a sealing boss 51 and a sealing groove 1233 being formed on the surface of the mounting through hole 1232 facing the outer side wall of the shaft seal 50; the sealing boss 51 being assembled into the sealing groove 1233 and having a clearance fit with the inner wall of the sealing groove 1233; there are multiple sealing bosses 51 and sealing grooves 1233; and the sealing bosses 51 and sealing grooves 1233 are arranged in a stepped manner along the axial direction of the rotor shaft 11.

[0079] Along the first direction, the outer casing 12 has a mounting seat 123 opposite to the secondary pressure roller 30. The mounting seat 123 can be fitted with the shell sidewall 122 of the outer casing 12. The mounting seat 123 can be fixedly connected to the shell sidewall 122 by means of snap-fit, bolt connection, etc. The mounting seat 123 and the shell sidewall 122 can jointly define the mounting cavity 121. The mounting seat 123 can be formed with a mounting through hole 1232 (i.e., the first through hole in the above embodiment). The mounting through hole 1232 can penetrate the mounting seat 123 along the thickness direction of the mounting seat 123. The rotor shaft 11 can pass through the mounting through hole 1232 and can rotate relative to the mounting seat 123. The shaft seal 50 can be made of aluminum alloy material and can be sleeved on the rotor shaft 11. The shaft seal 50 can be interference-fitted with the rotor shaft 11. When the rotor shaft 11 passes through the mounting through hole 1232, the shaft seal 50 can be located within the mounting through hole 1232, which can reduce the probability of gas leakage from the mounting cavity 121 to the secondary pressure roller 30. The outer wall of the shaft seal 50 has one of a sealing boss 51 and a sealing groove 1233 extending circumferentially along the shaft seal 50. The surface of the mounting through hole 1232 facing the outer wall of the shaft seal 50 has the other of the sealing boss 51 and the sealing groove 1233. This embodiment of the application uses the example of the outer wall of the shaft seal 50 having a sealing boss 51 and the surface of the mounting through hole 1232 facing the outer wall of the shaft seal 50 having a sealing groove 1233 for illustration.

[0080] The sealing boss 51 can be assembled into the sealing groove 1233. By setting the sealing boss 51 and the sealing groove 1233 to be assembled together, the probability of gas flowing from the mounting cavity 121 to the secondary pressure roller 30 can be reduced. When the rotor shaft 11 rotates, the rotor shaft 11 can drive the shaft seal 50 to rotate relative to the mounting base 123. There can be a gap between the sealing boss 51 and the inner wall of the sealing groove 1233. A small amount of gas in the mounting cavity 121 can flow into the gap between the sealing boss 51 and the inner wall of the sealing groove 1233. The gas can flow through the first air radial bearing 14, so that the first air radial bearing 14 can be cooled. If the gas flows to the secondary pressure roller 30, the gas can be compressed in the secondary pressure roller 30, realizing the effect of gas recycling and reducing gas loss.

[0081] There can be multiple sealing bosses 51 and multiple sealing grooves 1233. Each sealing boss 51 can be paired with a corresponding sealing groove 1233. The multiple sealing bosses 51 and sealing grooves 1233 can be arranged in a stepped manner along the axial direction of the rotor shaft 11. This stepped arrangement can extend the flow path of gas leaking from the mounting cavity 121 and reduce the gas flow rate to the secondary pressure roller 30.

[0082] In some embodiments of the present invention, the end face of the shaft seal 50 away from the first-stage pressure roller 20 is configured as a first abutting surface 52, and the inner surface of the mounting through hole 1232 is formed with a second abutting surface 1234. The first abutting surface 52 and the second abutting surface 1234 are opposite to each other along the axial direction of the rotor shaft 11, and the first abutting surface 52 and the second abutting surface 1234 abut against each other.

[0083] The first contact surface 52 and the second contact surface 1234 are arranged opposite each other along the first direction. The contact between the first contact surface 52 and the second contact surface 1234 can improve the sealing performance between the shaft seal 50 and the mounting base 123, which is beneficial to further reduce the gas flow to the secondary pressure roller 30 and improve the stability of the shaft seal 50 installation.

[0084] In some embodiments of the present invention, the gas compression assembly 1 for the centrifugal compressor may further include: a partition plate, which is sleeved on the rotor shaft 11 and located between the secondary pressure roller 30 and the tertiary pressure roller 40, so that the secondary pressure roller 30 and the tertiary pressure roller 40 are spaced apart.

[0085] A partition plate can be provided between the secondary pressure roller 30 and the tertiary pressure roller 40. The partition plate can separate the secondary pressure roller 30 and the tertiary pressure roller 40. The partition plate can be sleeved on the rotor shaft 11, thereby reducing the probability of gas flowing from the tertiary pressure roller 40 into the secondary pressure roller 30, which is beneficial to improving the safety of the gas compression assembly 1.

[0086] The partition plate can be assembled with the secondary pressure roller 30 and the tertiary pressure roller 40. As an example, the partition plate has a first side and a second side opposite to each other along a first direction. The first side can have one of a first mounting boss and a first mounting groove 321 formed therein. The surface of the secondary pressure roller back 32 facing the partition plate can have the other of a first mounting boss and a first mounting groove 321 formed therein. The first mounting boss can be assembled into the first mounting groove 321, and the first mounting boss can have a clearance fit with the first mounting groove 321. This embodiment of the application uses the example of a first mounting boss formed on the first side and a first mounting groove 321 formed on the surface of the secondary pressure roller back 32 facing the partition plate. The first mounting boss can be constructed as a ring structure, and the first mounting groove 321 can be constructed as a ring groove. There can be multiple first mounting bosses, which can be arranged sequentially along the radial direction of the partition plate. There can also be multiple first mounting grooves 321, which can be arranged sequentially along the radial direction of the secondary pressure roller back 32. Multiple first mounting bosses can be set one-to-one with multiple first mounting slots 321, and each first mounting boss has a corresponding first mounting slot 321 for assembly.

[0087] One of the second mounting boss and the second mounting groove 421 is formed on the second side surface. The other of the second mounting boss and the second mounting groove 421 is formed on the surface of the third-stage pressure roller back 42 facing the partition plate. The second mounting boss can be assembled into the second mounting groove 421, and the second mounting boss can be clearance-fitted with the second mounting groove 421. This embodiment of the application uses the formation of a second mounting boss on the second side surface and a second mounting groove 421 on the surface of the third-stage pressure roller back 42 facing the partition plate as an example. The second mounting boss can be constructed as a ring structure, and the second mounting groove 421 can be constructed as a ring groove. There can be multiple second mounting bosses, which can be arranged sequentially along the radial direction of the partition plate. There can also be multiple second mounting grooves 421, which can be arranged sequentially along the radial direction of the second-stage pressure roller back 32. Multiple second mounting bosses can be correspondingly arranged with multiple second mounting grooves 421, and each second mounting boss has a corresponding second mounting groove 421 for assembly.

[0088] The partition plate has one of a third mounting boss and a third mounting groove extending circumferentially along the rotor shaft 11 on its inner surface along the circumferential direction. The third mounting boss can be fitted into the third mounting groove, and the third mounting boss can be clearance-fitted into the third mounting groove. This embodiment of the application uses the example of a partition plate having a third mounting boss formed on its inner surface along the circumferential direction and a third mounting groove formed on the surface of the third mounting roller 40 facing the partition plate along the circumferential direction. There are multiple third mounting bosses and third mounting grooves, and each of the multiple third mounting bosses can be correspondingly set with a multiple third mounting groove. Both the third mounting bosses and third mounting grooves are arranged in a stepped manner along the axial direction of the rotor shaft 11.

[0089] By setting a clearance fit between the first mounting boss and the first mounting groove 321, and a clearance fit between the second mounting boss and the second mounting groove 421, the secondary pressure roller 30 and the tertiary pressure roller 40 can rotate smoothly relative to the partition plate. This helps to reduce the friction between the secondary pressure roller 30, the tertiary pressure roller 40 and the partition plate, and helps to extend the service life of the partition plate.

[0090] In some embodiments of the present invention, the motor 10 may include an air thrust bearing 70, a second air radial bearing 15, a back plate 80, and an end wall 90. The end wall 90 may be disposed opposite to and spaced apart from the mounting base 123 along a first direction. The mounting base 123, the end wall 90, and the housing side wall 122 together define a mounting cavity 121. The end wall 90 may be integrally formed with the inner side wall 1223. The end wall 90 may have a second through hole 91, through which the rotor shaft 11 may pass. The second air radial bearing 15 may be sleeved on the shaft section of the rotor shaft 11 near the first end, and the second air radial bearing 15 may be located within the second through hole 91. The second air radial bearing 15 may be fixedly connected to the end wall 90 by bolts, locating pins, etc. When the rotor shaft 11 rotates, the rotor shaft 11 may rotate relative to the second air radial bearing 15, thereby allowing the rotor shaft 11 to rotate relative to the end wall 90.

[0091] A back plate 80 can be disposed on the side of the end wall 90 opposite to the mounting base 123. The back plate 80 can be fixedly connected to the end wall 90 by bolts. The back plate 80 can form a third through hole 81. A first-stage pressure roller 20 can be disposed on the side of the back plate 80 opposite to the end wall 90. At least a portion of the first-stage pressure roller 20 can pass through the third through hole 81, and the back of the first-stage pressure roller 22 can abut against the back plate 80. At least a portion of the end wall 90 can be spaced apart from the back plate 80, and a gap is formed between the end wall 90 and the back plate 80. Along the first direction, an air thrust bearing 70 can be provided on the side of the second air radial bearing 15 opposite to the first air radial bearing 14. There can be two air thrust bearings 70, one of which can abut against the end wall 90, and the other can abut against the back plate 80. The two air thrust bearings 70 are located in the gap between the end wall 90 and the back plate 80. Two air thrust bearings 70 can be fixed to the end wall 90 and the back plate 80 respectively by locating pins. A thrust plate 71 can be provided between the two air thrust bearings 70. The two air thrust bearings 70 are spaced apart, and the air thrust bearings 70 can support the rotor shaft 11 and reduce the axial movement of the rotor shaft 11. By placing the two air thrust bearings 70 in the gap between the end wall 90 and the back plate 80, it is beneficial to reduce the length of the motor 10 along the first direction and reduce the space occupied by the motor 10.

[0092] As an example, the inner wall of the third through hole 81 has one of a fourth mounting boss and a fourth mounting groove extending circumferentially along the back plate 80. The surface of the first-stage pressure roller 20 opposite to the inner wall of the third through hole 81 along the circumferential direction has the other of a fourth mounting boss and a fourth mounting groove. The fourth mounting boss can be assembled into the fourth mounting groove, and the fourth mounting boss can be clearance-fitted with the fourth mounting groove. This application embodiment is described with the example of the fourth mounting groove being formed on the inner wall of the third through hole 81 and the fourth mounting boss being formed on the surface of the first-stage pressure roller 20 opposite to the inner wall of the third through hole 81 along the circumferential direction. There can be multiple fourth mounting bosses and fourth mounting grooves. Multiple fourth mounting bosses can be arranged one-to-one with multiple fourth mounting grooves. Both the fourth mounting bosses and fourth mounting grooves can be arranged sequentially along the first direction.

[0093] According to a second aspect of the present invention, a centrifugal compressor includes the gas compression assembly 1 described in the above embodiments.

[0094] According to the embodiments of this application, the centrifugal compressor using the gas compression assembly 1 in the above embodiments can reduce the axial force on the centrifugal compressor, which is beneficial to improving the reliability of the centrifugal compressor.

[0095] Other configurations and operations of the gas compression assembly 1 and the centrifugal compressor according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here.

[0096] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0097] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A gas compression assembly for a centrifugal compressor, characterized in that, include: An electric motor (10) having a rotor shaft (11); A primary pressure roller (20) is fixed to the first end of the rotor shaft (11). The primary pressure roller (20) has a primary pressure roller nose (21) and a primary pressure roller back (22). The primary pressure roller nose (21) is located on the side of the primary pressure roller back (22) away from the motor (10). A secondary pressure roller (30) is fixed to the second end of the rotor shaft (11). The secondary pressure roller (30) has a secondary pressure roller nose (31) and a secondary pressure roller back (32). The secondary pressure roller back (32) is located on the side of the secondary pressure roller nose (31) away from the motor (10). The secondary pressure roller (30) is used to compress the gas compressed by the primary pressure roller (20). A third-stage pressure roller (40) is fixed to the second end of the rotor shaft (11) and located on the side of the second-stage pressure roller (30) away from the motor (10). The third-stage pressure roller (40) has a third-stage pressure roller nose (41) and a third-stage pressure roller back (42). The third-stage pressure roller nose (41) is located on the side of the third-stage pressure roller back (42) away from the motor (10). The third-stage pressure roller (40) is used to compress the gas compressed by the second-stage pressure roller (30). The outer diameter of the first-stage pressure roller back (22) is D1, the outer diameter of the second-stage pressure roller back (32) is D2, and the outer diameter of the third-stage pressure roller back (42) is D3, satisfying the relationship: D1:D2:D3 = 1:0.77:0.84; The first-stage pressure impeller (20) and the second-stage pressure impeller (30) are closed impellers, and the third-stage pressure impeller (40) is an open impeller.

2. The gas compression assembly according to claim 1, characterized in that, The outer diameter of the first-stage pressure roller nose (21) is D4, which satisfies the following relationship: 130mm≤D1≤134mm, 82mm≤D4≤86mm; The outer diameter of the secondary pressure roller nose (31) is D5, which satisfies the following relationship: 99mm≤D2≤102mm, 78mm≤D5≤82mm; The outer diameter of the three-stage pressure roller nose (41) is D6, which satisfies the following relationship: 108mm≤D3≤112mm, 58mm≤D6≤62mm.

3. The gas compression assembly according to claim 1, characterized in that, The gas pressure inside the motor (10) is higher than the gas pressure at the back (22) of the first-stage pressure roller, and the gas pressure inside the motor (10) is higher than the gas pressure at the nose (31) of the second-stage pressure roller.

4. The gas compression assembly according to any one of claims 1-3, characterized in that, The motor (10) also has a housing (12) and a stator (13). The housing (12) defines a mounting cavity (121). The stator (13) is disposed in the mounting cavity (121) and fixed to the housing sidewall (122) of the housing (12). The rotor shaft (11) is rotatably disposed in the housing (12) and passes through the housing (12). The housing sidewall (122) has a wire outlet hole (1221) communicating with the mounting cavity (121). The wire outlet hole (1221) is located at the end of the housing sidewall (122) away from the first-stage pressure roller (20). The electrical connection wire of the stator (13) is installed in the wire outlet hole (1221).

5. The gas compression assembly according to any one of claims 1-3, characterized in that, The motor (10) also has a housing (12) with a mounting base (123) opposite to the secondary pressure roller (30). The rotor shaft (11) passes through the mounting base (123) and is rotatable relative to the mounting base (123). A flow guide structure (1231) is formed on the surface of the mounting base (123) facing the secondary pressure roller (30). The flow guide structure (1231) is configured to guide the gas compressed by the primary pressure roller (20) to the secondary pressure roller (30).

6. The gas compression assembly according to any one of claims 1-3, characterized in that, The motor (10) also has an outer casing (12), and a cooling channel (1222) is formed in the side wall (122) of the outer casing (12), and a heat dissipation structure is formed on the inner surface of the cooling channel (1222).

7. The gas compression assembly according to any one of claims 1-3, characterized in that, Also includes: A partition plate is sleeved on the rotor shaft (11) and located between the secondary pressure roller (30) and the tertiary pressure roller (40) to separate the secondary pressure roller (30) and the tertiary pressure roller (40).

8. A centrifugal compressor, characterized in that, Includes the gas compression assembly (1) according to any one of claims 1-7.

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