Rotor shaft, rotor assembly and air circulator

Abstract

The application provides a rotor shaft, a rotor assembly and an air circulating machine. The rotor shaft comprises a reference shaft section (1), a first shaft section (2), a second shaft section (3) and a third shaft section (4), the first shaft section (2) is configured to assemble an expansion impeller (8), the second shaft section (3) is configured to assemble a compression impeller (9), the third shaft section (4) is configured to assemble a fan impeller (10), the first shaft section (2) and the second shaft section (3) are arranged at two ends of the reference shaft section (1), end faces of the two ends of the reference shaft section (1) form axial positioning faces (17), the reference shaft section (1) has a diameter D1, the first shaft section (2) has a diameter D2, the second shaft section (3) has a diameter D3, the third shaft section (4) has a diameter D4, D1>D2, D1>D3>=D4. According to the rotor shaft, the positioning precision during the installation of the compression impeller, the expansion impeller and the fan impeller can be improved.

Description

Technical Field

[0001] This application relates to the field of aircraft air conditioning technology, specifically to a rotor shaft, rotor assembly, and air circulator. Background Technology

[0002] A compressed air circulation refrigeration system using air as the working fluid employs a turbine compressor for compression and an expander for expansion. The system also requires a fan to drive airflow and remove heat from the heat exchanger. The expander, compressor, and fan are combined into an air circulator, which includes a rotor assembly and stationary components. The rotor assembly, supported by a bearing system, rotates at high speed.

[0003] To assemble a rotor assembly comprising a compressor impeller, an expansion impeller, and a fan impeller into a single rotor assembly and ensure its reliable high-speed rotation, a journal shaft is disclosed in the related art. The journal shaft connects the impellers, a cylindrical tie rod passes through the journal shaft and all the impellers, and clamping members apply loads to fix the compressor rotor, turbine rotor, and fan impeller relative to the tie rod. In this journal shaft, the compressor impeller, expansion impeller, and fan impeller are positioned relative to each other using the clamping members, but the positioning references are inconsistent, resulting in low positioning accuracy. Summary of the Invention

[0004] Therefore, the technical problem to be solved by this application is to provide a rotor shaft, rotor assembly and air circulator that can improve the positioning accuracy of the compressor impeller, expansion impeller and fan impeller during installation.

[0005] To address the aforementioned problems, this application provides a rotor shaft comprising a reference shaft section, a first shaft section, a second shaft section, and a third shaft section. The first shaft section is configured to assemble an expansion impeller, the second shaft section is configured to assemble a compression impeller, and the third shaft section is configured to assemble a fan impeller. The first and second shaft sections are disposed at both ends of the reference shaft section, and the end faces of the two ends of the reference shaft section form axial positioning surfaces. The diameter of the reference shaft section is D1, the diameter of the first shaft section is D2, the diameter of the second shaft section is D3, and the diameter of the third shaft section is D4, where D1 > D2 and D1 > D3 ≥ D4.

[0006] Preferably, a fourth shaft segment is provided between the first shaft segment and the reference shaft segment. The fourth shaft segment is configured to install a thrust plate, and the diameter of the fourth shaft segment is D5, where D1 > D5 ≥ D2.

[0007] Preferably, the length of the reference shaft segment is L1, and L1 / D1 = 1.1 to 2.0.

[0008] Preferably, L1 / D1 = 1.69.

[0009] Preferably, the length of the second shaft segment is L3, and L3 / D3 = 1 to 7.4.

[0010] Preferably, L3 / D3 = 1.53 to 5.4.

[0011] Preferably, the length of the fourth shaft segment is L5, and L5 / D5 = 0.3 to 2.5.

[0012] Preferably, L5 / D5 = 0.5.

[0013] Preferably, a fifth shaft segment is provided between the second shaft segment and the third shaft segment. The fifth shaft segment is configured to install an axial positioning component, and the diameter of the fifth shaft segment is D6, where D3 ≥ D6.

[0014] Preferably, a sixth shaft segment is provided between the second shaft segment and the third shaft segment. The sixth shaft segment is configured to install a radial journal, and the diameter of the sixth shaft segment is D7, where D3 ≥ D7.

[0015] Preferably, locking bolt holes are provided at both ends of the rotor shaft, and locking bolt assemblies are installed in the locking bolt holes.

[0016] Preferably, a fourth shaft segment is provided between the first shaft segment and the reference shaft segment, and a fifth and a sixth shaft segment are provided between the second and third shaft segments. The fifth and second shaft segments are arranged sequentially along the direction away from the reference shaft segment. The diameter of the fourth shaft segment is D5, the diameter of the fifth shaft segment is D6, the diameter of the sixth shaft segment is D7, D1 > D5 > D2, and / or, D1 > D3 > D6 > D7 > D4.

[0017] According to another aspect of this application, a rotor assembly is provided, including a rotor shaft, which is the rotor shaft described above.

[0018] Preferably, when the rotor shaft includes a reference shaft section, a first shaft section, a second shaft section, a third shaft section, a fourth shaft section, a fifth shaft section, and a sixth shaft section, the rotor assembly further includes an expansion impeller, a compression impeller, a fan impeller, a thrust disc, an axial positioning component, a radial journal, and an axial balancing component. The expansion impeller is mounted on the first shaft section, the compression impeller is mounted on the second shaft section, the axial balancing component and the fan impeller are mounted on the third shaft section, the thrust disc is mounted on the fourth shaft section, the axial positioning component is mounted on the fifth shaft section, and the radial journal is mounted on the sixth shaft section.

[0019] According to another aspect of this application, an air circulator is provided, including a rotor assembly, which is the rotor assembly described above.

[0020] The rotor shaft provided in this application includes a reference shaft section, a first shaft section, a second shaft section, and a third shaft section. The first shaft section is configured to assemble an expansion impeller, the second shaft section is configured to assemble a compression impeller, and the third shaft section is configured to assemble a fan impeller. The first and second shaft sections are located at both ends of the reference shaft section, and the end faces of the reference shaft section form axial positioning surfaces. The diameter of the reference shaft section is D1, the diameter of the first shaft section is D2, the diameter of the third shaft section is D3, and the diameter of the fourth shaft section is D4, where D1 > D2 and D1 > D3 ≥ D4. This rotor shaft uses the reference shaft section as a positioning reference to achieve axial positioning of the expansion impeller, compression impeller, and fan impeller during installation. This enables a unified positioning reference, reduces positioning errors, improves positioning accuracy, and enhances the assembly accuracy of the rotor assembly. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of an air circulator according to an embodiment of this application;

[0022] Figure 2 This is a schematic diagram of the gas flow in the air circulator according to an embodiment of this application;

[0023] Figure 3 This is a three-dimensional structural diagram of the rotor shaft according to an embodiment of this application;

[0024] Figure 4 This is a cross-sectional structural schematic diagram of the rotor shaft according to an embodiment of this application;

[0025] Figure 5 This is a cross-sectional view of the rotor assembly according to an embodiment of this application;

[0026] Figure 6 This is a cross-sectional view of the rotor assembly according to an embodiment of this application;

[0027] Figure 7 This is an exploded view of the rotor assembly according to an embodiment of this application;

[0028] Figure 8 This is a sensor arrangement diagram of the rotor assembly according to an embodiment of this application;

[0029] Figure 9 This is a diagram showing the rotor trajectory of the air circulator according to an embodiment of this application at a rotational speed of n.

[0030] The reference numerals in the attached figures are as follows:

[0031] 1. Reference shaft section; 2. First shaft section; 3. Second shaft section; 4. Third shaft section; 5. Fourth shaft section; 6. Fifth shaft section; 7. Sixth shaft section; 8. Expansion impeller; 9. Compression impeller; 10. Fan impeller; 11. Thrust plate; 12. Radial journal; 13. Locking bolt hole; 14. Locking bolt assembly; 15. Axial positioning component; 16. Axial balancing component; 17. Axial positioning surface; 18. Expansion shell; 19. Compression shell; 20. Fan base; 21. Bearing. Detailed Implementation

[0032] See also Figures 1 to 9 As shown, according to an embodiment of this application, the rotor shaft includes a reference shaft segment 1, a first shaft segment 2, a second shaft segment 3, and a third shaft segment 4. The first shaft segment 2 is configured to assemble an expansion impeller 8, the second shaft segment 3 is configured to assemble a compression impeller 9, and the third shaft segment 4 is configured to assemble a fan impeller 10. The first shaft segment 2 and the second shaft segment 3 are disposed at both ends of the reference shaft segment 1. The end faces of the two ends of the reference shaft segment 1 form axial positioning surfaces 17. The diameter of the reference shaft segment 1 is D1, the diameter of the first shaft segment 2 is D2, the diameter of the second shaft segment 3 is D3, and the diameter of the third shaft segment 4 is D4, where D1 > D2 and D1 > D3 ≥ D4.

[0033] The rotor shaft uses the reference shaft section 1 as the positioning reference to achieve axial positioning of the expansion impeller 8, compression impeller 9 and wind impeller 10 during the installation process. This enables the positioning reference to be unified, reduces positioning errors, improves positioning accuracy, and improves the assembly accuracy of the rotor assembly.

[0034] In this embodiment, each shaft segment is coaxially arranged with the reference shaft segment 1, and each shaft segment is a cylindrical segment, which realizes the installation and positioning of other components of the rotor assembly. Since each shaft segment uses the reference shaft segment 1 as the machining and installation reference, the machining and installation reference is unified, which can reduce the number of components required for positioning, while improving the installation and positioning accuracy and the assembly accuracy of the rotor assembly.

[0035] In one embodiment, a fourth shaft segment 5 is provided between the first shaft segment 2 and the reference shaft segment 1. The fourth shaft segment 5 is configured to mount the thrust plate 11, and the diameter of the fourth shaft segment 5 is D5, where D1 > D5 ≥ D2. The fourth shaft segment 5 is positioned between the first shaft segment 2 and the reference shaft segment 1, such that the thrust plate 11 is positioned between the reference shaft segment 1 and the expansion impeller 8. The reference shaft segment 1 can be used to determine the axial installation accuracy of the thrust plate 11, and the thrust plate 11 can be used to determine the axial installation progress of the expansion impeller 8. In a preferred embodiment, D5 > D2, ensuring a clearance fit between the thrust plate 11 and the first shaft segment 2 when the thrust plate 11 passes through it. This reduces the installation and disassembly resistance of the thrust plate 11, lowers the difficulty of installation and disassembly, and improves the assembly efficiency of the thrust plate 11, without compromising the installation accuracy between the thrust plate 11 and the expansion impeller 8.

[0036] In one embodiment, the length of the reference shaft segment 1 is L1, and L1 / D1 = 1.1 to 2.0.

[0037] Preferably, L1 / D1 = 1.69.

[0038] If the ratio is too small, it will be difficult to arrange the bearing 21 on the reference shaft segment 1; if the ratio is too large, it will increase the axial dimension of the rotor shaft, reduce the stiffness of the rotor shaft, and make it difficult to achieve high-speed operation of the rotor assembly.

[0039] In one embodiment, the length of the second shaft segment 3 is L3, and L3 / D3 = 1 to 7.4.

[0040] Preferably, L3 / D3 = 1.53 to 5.4.

[0041] If the ratio is too small, the axial length of the second shaft section 3 used to install the compressor impeller 9 will be too small, making it difficult to assemble the compressor impeller 9 with the rotor shaft. If the ratio is too large, the axial dimension of the rotor shaft will be lengthened, the rigidity of the rotor shaft will be reduced, and it will be difficult to achieve high-speed operation of the rotor assembly.

[0042] When the ratio is between 1.53 and 5.4, the diameter of the shaft segments between the second shaft segment 3 and the third shaft segment 4 can be the same, eliminating the steps between these shaft segments and reducing the machining difficulty of the rotor shaft.

[0043] In one embodiment, the length of the fourth shaft segment 5 is L5, and L5 / D5 = 0.3 to 2.5.

[0044] Preferably, L5 / D5 = 0.5.

[0045] If the ratio is too small, the axial length of the fourth shaft segment 5 will be too short, which is not conducive to the fastening assembly between the thrust plate 11 and the fourth shaft segment 5 of the rotor shaft. If the ratio is too large, the axial dimension of the rotor shaft will be lengthened, the rigidity of the rotor shaft will be reduced, which is not conducive to the high-speed operation of the rotor assembly.

[0046] In one embodiment, a fifth shaft segment 6 is provided between the second shaft segment 3 and the third shaft segment 4. The fifth shaft segment 6 is configured to install the axial positioning element 15. The diameter of the fifth shaft segment 6 is D6, and D3 ≥ D6.

[0047] In one embodiment, a sixth shaft segment 7 is provided between the second shaft segment 3 and the third shaft segment 4. The sixth shaft segment 7 is configured to mount a radial journal 12. The diameter of the sixth shaft segment 7 is D7, and D3 ≥ D7.

[0048] In one embodiment, locking bolt holes 13 are provided at both ends of the rotor shaft, and locking bolt assemblies 14 are installed in the locking bolt holes 13.

[0049] In one embodiment, a fourth shaft segment 5 is provided between the first shaft segment 2 and the reference shaft segment 1, and a fifth shaft segment 6 and a sixth shaft segment 7 are provided between the second shaft segment 3 and the third shaft segment 4. The fifth shaft segment 6 and the second shaft segment 3 are arranged sequentially in a direction away from the reference shaft segment 1. The diameter of the fourth shaft segment 5 is D5, the diameter of the fifth shaft segment 6 is D6, the diameter of the sixth shaft segment 7 is D7, D1 > D5 > D2, and / or, D1 > D3 > D6 > D7 > D4.

[0050] When D1 > D3 > D6 > D7 > D4, the diameters of each shaft segment decrease sequentially along the direction away from the reference shaft segment 1. During the installation of the compression impeller 10, this facilitates the inner cylindrical surface of the compression impeller 10 to successively pass over the outer cylindrical surfaces of the third shaft segment 4, the sixth shaft segment 7, and the fifth shaft segment 6, and then make an interference fit with the outer cylindrical surface of the second shaft segment 3, achieving precise radial positioning of the compression impeller 10. The compression impeller 10 is in contact with the axial positioning surface 17 of the reference shaft segment 1 at its end face, achieving precise axial positioning of the compression impeller 10. Referring to the cylindrical surface of the reference shaft segment 1, the coaxiality of the cylindrical surface of the second shaft segment 3 can be controlled. The coaxiality is preferably 0.005 to 0.02 mm, which is beneficial for controlling the gap J02 between the compression impeller 10 and the compression housing 19.

[0051] When D6 > D7 > D4, the inner cylindrical surface of the axial positioning component 15 successively passes through the outer cylindrical surfaces of the third shaft segment 4 and the sixth shaft segment 7, and then is interference-fitted with the outer cylindrical surface of the fifth shaft segment 6. The end face of the axial positioning component 15 is in contact with the end face of the compression impeller 10, which on the one hand restricts the axial displacement of the compression impeller 10, and on the other hand realizes the axial positioning of the axial positioning component 15. Referring to the cylindrical surface of the reference shaft segment 1, the coaxiality of the cylindrical surface of the fifth shaft segment 6 can be controlled. The coaxiality is preferably 0.005~0.02mm, thereby ensuring that the rotor shaft can achieve high-precision dynamic balance requirements.

[0052] When D7 > D4, the inner cylindrical surface of the radial journal 12 passes through the outer cylindrical surface of the third shaft segment 4 and is interference-fitted with the outer cylindrical surface of the sixth shaft segment 7. The end face of the radial journal 12 is fitted with the end face of the axial positioning component 15. Referring to the cylindrical surface of the reference shaft segment 1, the coaxiality of the outer cylindrical surfaces of the fifth shaft segment 6 and the sixth shaft segment 7 is controlled, preferably between 0.005 and 0.02 mm. The radial journal 12 is supported by bearing 21, and the reference shaft segment 1 is supported by another bearing 21. Controlling the coaxiality of the outer cylindrical surfaces of the fifth shaft segment 6 and the sixth shaft segment 7 with reference to the cylindrical surface of the reference shaft segment 1 helps to achieve the high-precision coaxiality requirements of the bearing support portion of the rotor shaft.

[0053] The cylindrical surface of the axial balancing component 16 is interference-fitted with the outer cylindrical surface of the fourth shaft segment 5. The end face of the axial balancing component 16 is fitted with the end face of the radial journal 12. The inner cylindrical surface of the impeller 10 is interference-fitted with the outer cylindrical surface of the fourth shaft segment 5, and the end face of the impeller 10 is fitted with the end face of the axial balancing component 16, thus achieving the assembly of the impeller 10. Referring to the cylindrical surface of the reference shaft segment 1, the coaxiality of the outer cylindrical surface of the fourth shaft segment 5 can be controlled, preferably between 0.005 and 0.02 mm, which facilitates the control of the clearance J03 between the impeller 10 and the fan base 20.

[0054] The order D1 > D5 > D2 facilitates the inner cylindrical surface of the thrust plate 11 to pass through the outer cylindrical surface of the first shaft segment 2 and then be assembled with the outer cylindrical surface of the fourth shaft segment 5 via an interference fit. Simultaneously, the end face of the thrust plate 11 is fitted with the axial positioning surface 17 of the reference shaft segment 1, achieving the positioning and assembly of the thrust plate 11. Referring to the cylindrical surface of the reference shaft segment 1, the coaxiality of the cylindrical surface of the first shaft segment 2 can be controlled, preferably between 0.005 and 0.02 mm, thereby ensuring that the rotor shaft meets the high-precision dynamic balance requirements.

[0055] The inner cylindrical surface of the expansion impeller 8 is interference-fitted with the outer cylindrical surface of the first shaft section 2. The end face of the expansion impeller 8 is in contact with the end face of the thrust plate 11, achieving positioning and assembly of the expansion impeller 8. By referring to the cylindrical surface of the reference shaft section 1, the coaxiality of the outer cylindrical surface of the first shaft section 2 can be controlled, preferably 0.005 to 0.02 mm, which is beneficial for controlling the clearance J01 between the expansion impeller 8 and the expansion housing 18.

[0056] The optical shaft portion of the locking bolt assembly 14 used to lock the expansion impeller 8 is precisely guided and positioned by the positioning shaft hole section of the locking bolt hole 13 on the first shaft section 2, and screwed into the shaft thread to achieve locking on the expansion impeller side. The optical shaft portion of the locking bolt assembly 14 used to lock the fan blade is precisely guided and positioned by the positioning shaft hole section of the locking bolt hole 13 on the third shaft section 4, and screwed into the shaft thread to achieve locking on the fan blade side. Referring to the cylindrical surface of the reference shaft section 1, the coaxiality of the positioning shaft hole sections of the locking bolt hole 13 on the first shaft section 2 and the third shaft section 4 is controlled respectively. The coaxiality is preferably 0.005~0.02mm, thereby controlling the thread fit accuracy and ensuring that the rotor shaft can achieve high-precision dynamic balance requirements.

[0057] According to an embodiment of this application, the rotor assembly includes a rotor shaft, which is the rotor shaft described above.

[0058] When the rotor shaft includes a reference shaft section 1, a first shaft section 2, a second shaft section 3, a third shaft section 4, a fourth shaft section 5, a fifth shaft section 6, and a sixth shaft section 7, the rotor assembly also includes an expansion impeller 8, a compression impeller 9, a fan impeller 10, a thrust plate 11, an axial positioning component 15, a radial journal 12, and an axial balancing component 16. The expansion impeller 8 is mounted on the first shaft section 2, the compression impeller 9 is mounted on the second shaft section 3, the axial balancing component 16 and the fan impeller 10 are mounted on the third shaft section 4, the thrust plate 11 is mounted on the fourth shaft section 5, the axial positioning component 15 is mounted on the fifth shaft section 6, and the radial journal 12 is mounted on the sixth shaft section 7.

[0059] According to an embodiment of this application, the air circulator includes a rotor assembly, which is the rotor assembly described above.

[0060] In this embodiment, the air circulator is used to compress air. The air circulator includes a rotor assembly, a housing assembly, a bearing system, a dynamic and static sealing system, and fasteners. The fasteners assemble the bearing system, the dynamic and static sealing system, and the housing assembly into a stationary assembly, and the bearing system supports the rotor assembly to rotate at high speed.

[0061] The rotational power of the rotor assembly comes from the expansion work of the gas. After the gas flows into T01, it expands and does work through the expansion impeller 8. The temperature of the gas decreases after the work is done, and the low-temperature gas flows out from T02 and is transported to the area that needs cooling. The expansion work drives the rotor assembly to rotate. The rotating compression impeller 9 draws in the gas from CO1, compresses it, and discharges it from CO2. At the same time, the rotating fan impeller 10 draws in air from F01 and discharges it at F02, driving the airflow.

[0062] A cross-section A01 is perpendicular to the central axis of the rotor shaft. A pair of mutually perpendicular eddy current displacement sensors C1 and C2 are arranged on cross-section A01. The displacement of the surface of the axial positioning component 15 is measured to monitor the rotational motion state of the rotor assembly. The signal of C1 is used as the abscissa and C2 as the ordinate to obtain the rotor motion trajectory diagram under rotational conditions.

[0063] See Figure 9 The figure shows the rotor trajectory when rotating at a high speed of 52444 RPM. As can be seen from the figure, the rotor trajectory is smooth; therefore, the rotor assembly of the above embodiment of this application has good operational stability.

[0064] It will be readily understood by those skilled in the art that the aforementioned advantageous methods can be freely combined and superimposed without conflict.

[0065] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A rotor shaft, characterized in that, The shaft includes a reference shaft section (1), a first shaft section (2), a second shaft section (3), and a third shaft section (4). The first shaft section (2) is configured to assemble an expansion impeller (8), the second shaft section (3) is configured to assemble a compression impeller (9), and the third shaft section (4) is configured to assemble a wind impeller (10). The first shaft section (2) and the second shaft section (3) are located at both ends of the reference shaft section (1). The end faces of the two ends of the reference shaft section (1) form an axial positioning surface (17). The diameter of the reference shaft section (1) is D1, the diameter of the first shaft section (2) is D2, the diameter of the second shaft section (3) is D3, and the diameter of the third shaft section (4) is D4. D1 > D2. A fifth shaft segment (6) and a sixth shaft segment (7) are provided between the second shaft segment (3) and the third shaft segment (4). The fifth shaft segment (6) and the second shaft segment (3) are arranged sequentially along the direction away from the reference shaft segment (1). The diameter of the fifth shaft segment (6) is D6, and the diameter of the sixth shaft segment (7) is D7, D1>D3>D6>D7>D4, so as to achieve precise radial and axial positioning of the compression impeller (9). Among them, the coaxiality of the cylindrical surface of the second shaft segment (3) is 0.005 to 0.02 mm, with reference to the cylindrical surface of the reference shaft segment (1). The length of the reference shaft segment (1) is L1, and L1 / D1 = 1.1 to 2.

0.

2. The rotor shaft according to claim 1, characterized in that, A fourth shaft segment (5) is provided between the first shaft segment (2) and the reference shaft segment (1). The fourth shaft segment (5) is configured to install a thrust plate (11). The diameter of the fourth shaft segment (5) is D5, where D1 > D5 ≥ D2.

3. The rotor shaft according to claim 1, characterized in that, L1 / D1 = 1.

69.

4. The rotor shaft according to claim 1, characterized in that, The length of the second shaft segment (3) is L3, and L3 / D3 = 1 to 7.

4.

5. The rotor shaft according to claim 4, characterized in that, L3 / D3 = 1.53 to 5.

4.

6. The rotor shaft according to claim 2, characterized in that, The length of the fourth shaft segment (5) is L5, and L5 / D5 = 0.3 to 2.

5.

7. The rotor shaft according to claim 6, characterized in that, L5 / D5 = 0.

5.

8. The rotor shaft according to claim 1, characterized in that, A fifth shaft segment (6) is provided between the second shaft segment (3) and the third shaft segment (4). The fifth shaft segment (6) is configured to install an axial positioning component (15). The diameter of the fifth shaft segment (6) is D6, and D3 ≥ D6.

9. The rotor shaft according to claim 1, characterized in that, A sixth shaft segment (7) is provided between the second shaft segment (3) and the third shaft segment (4). The sixth shaft segment (7) is configured to mount a radial journal (12). The diameter of the sixth shaft segment (7) is D7, and D3 ≥ D7.

10. The rotor shaft according to claim 1, characterized in that, Locking bolt holes (13) are provided at both ends of the rotor shaft, and locking bolt assemblies (14) are installed in the locking bolt holes (13).

11. The rotor shaft according to claim 1, characterized in that, A fourth shaft segment (5) is provided between the first shaft segment (2) and the reference shaft segment (1), and the diameter of the fourth shaft segment (5) is D5, where D1 > D5 > D2.

12. A rotor assembly, characterized in that, Includes a rotor shaft, wherein the rotor shaft is the rotor shaft according to any one of claims 1 to 11.

13. The rotor assembly according to claim 12, characterized in that, When the rotor shaft includes a reference shaft section (1), a first shaft section (2), a second shaft section (3), a third shaft section (4), a fourth shaft section (5), a fifth shaft section (6), and a sixth shaft section (7), the rotor assembly also includes an expansion impeller (8), a compression impeller (9), a fan impeller (10), a thrust plate (11), an axial positioning component (15), a radial journal (12), and an axial balancing component (16). The expansion impeller (8) is mounted on the first shaft section (2), the compression impeller (9) is mounted on the second shaft section (3), the axial balancing component (16) and the fan impeller (10) are mounted on the third shaft section (4), the thrust plate (11) is mounted on the fourth shaft section (5), the axial positioning component (15) is mounted on the fifth shaft section (6), and the radial journal (12) is mounted on the sixth shaft section (7).

14. An air circulator, comprising a rotor assembly, characterized in that, The rotor assembly is the rotor assembly as described in claim 12 or 13.

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