Motor shaft and magnetic levitation motor

Abstract

The present application provides a motor shaft and a magnetic suspension motor. The motor shaft includes a front short shaft, a rear short shaft, a core shaft, a front magnetic suspension bearing, a rear magnetic suspension bearing, a magnetic steel ring, a first magnetic isolation ring and a second magnetic isolation ring. The core shaft is arranged between the front short shaft and the rear short shaft, the front magnetic suspension bearing is sleeved on the front short shaft, the rear magnetic suspension bearing is sleeved on the rear short shaft, the magnetic steel ring is sleeved outside the core shaft, the first magnetic isolation ring and the second magnetic isolation ring are sleeved outside the core shaft, the magnetic steel ring is located between the first magnetic isolation ring and the second magnetic isolation ring, the front short shaft and / or the rear short shaft are made of magnetic conductive material, the outer diameter of the first magnetic isolation ring and the second magnetic isolation ring is the same as the outer diameter of the magnetic steel ring, and the inner diameter of the first magnetic isolation ring and / or the second magnetic isolation ring is smaller than the inner diameter of the magnetic steel ring. According to the motor shaft of the present application, the output of the magnetic suspension bearing can be increased while effectively avoiding the interference of the magnetic field of the magnetic steel ring with the magnetic field of the magnetic suspension bearing.

Description

Technical Field

[0001] The present application relates to the technical field of motors, and in particular to a motor shaft and a magnetic levitation motor. Background Art

[0002] High-speed permanent magnet synchronous motor has many advantages such as high power density, good dynamic response and simple structure, and has become one of the research hotspots in the international electrical engineering field. However, the permanent magnets in its rotor are generally made of sintered NdFeB permanent magnet materials. Since this permanent magnet material is resistant to compression but not to tension, in order to ensure that the permanent magnet has sufficient strength at high speed, a high-strength rotor sheath is generally wrapped outside the permanent magnet. The rotor sheath and the permanent magnet adopt an interference fit to ensure that the permanent magnet still bears a certain compressive stress during operation, thereby ensuring the safe operation of the high-speed motor.

[0003] The prior art provides a surface-mounted high-speed permanent magnet motor rotor structure, which adopts a three-section annular magnetic steel ring structural design, in which the magnetic core is made of magnetic conductive material, while the shaft end pieces and the shaft end pieces at both ends are made of non-magnetic conductive material, in order to block the axial magnetic circuit and reduce axial leakage magnetic flux.

[0004] The disadvantage of this type of three-section shaft design is that only non-magnetic materials can be used for its front and rear short shafts. This is because if magnetic materials are used, annular magnetic steel rings will form a leakage magnetic circuit in the axial direction, causing interference with the magnetic field of the magnetic bearings at both ends of the rotating shaft, increasing the difficulty of controlling the magnetic bearings and reducing the control accuracy of the magnetic bearings. Using non-magnetic materials for the front and rear short shafts will limit the magnetic circuit of the magnetic bearings, making it easier for the magnetic circuit of the magnetic bearing rotor to reach saturation, thereby reducing the bearing output. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present application is to provide a motor shaft and a magnetic levitation motor, which can increase the output of the magnetic levitation bearing while effectively avoiding the interference of the magnetic field of the magnetic steel ring on the magnetic field of the magnetic levitation bearing.

[0006] In order to solve the above problems, the present application provides a motor shaft, including a front short shaft, a rear short shaft, a core shaft, a front magnetic suspension bearing, a rear magnetic suspension bearing, a magnetic steel ring, a first magnetic isolation ring and a second magnetic isolation ring, the core shaft is arranged between the front short shaft and the rear short shaft, the front magnetic suspension bearing is sleeved on the front short shaft, the rear magnetic suspension bearing is sleeved on the rear short shaft, the magnetic steel ring is sleeved outside the core shaft, the first magnetic isolation ring and the second magnetic isolation ring are sleeved outside the core shaft, the magnetic steel ring is located between the first magnetic isolation ring and the second magnetic isolation ring, the front short shaft and / or the rear short shaft are made of magnetic conductive material, the outer diameters of the first magnetic isolation ring and the second magnetic isolation ring are the same as the outer diameter of the magnetic steel ring, and the inner diameter of the first magnetic isolation ring and / or the second magnetic isolation ring is smaller than the inner diameter of the magnetic steel ring.

[0007] Preferably, the core shaft is integrally formed with the front short shaft or the rear short shaft.

[0008] Preferably, the core shaft and the rear short shaft are integrally formed, the inner diameter of the second magnetic isolation ring is smaller than the inner diameter of the magnetic steel ring, an annular groove is provided at the connection position between the core shaft and the rear short shaft, and the second magnetic isolation ring is provided in the annular groove.

[0009] Preferably, the second magnetic isolation ring comprises at least two ring segments, and the at least two ring segments are combined to form the second magnetic isolation ring.

[0010] Preferably, the inner diameter of the first magnetic isolation ring is smaller than or equal to the inner diameter of the magnetic steel ring.

[0011] Preferably, the first magnetic isolation ring is integrally formed, or the first magnetic isolation ring includes at least two ring segments, and the at least two ring segments are combined to form the first magnetic isolation ring.

[0012] Preferably, the radial thickness of the second magnetic isolation ring is H1, and the radial thickness of the magnetic steel ring is H2, wherein 1.1≤H1 / H2≤1.4.

[0013] Preferably, the core shaft and the front short shaft are integrally formed, the inner diameter of the first magnetic isolation ring is smaller than the inner diameter of the magnetic steel ring, an annular groove is provided at the connection position between the core shaft and the front short shaft, and the first magnetic isolation ring is provided in the annular groove.

[0014] Preferably, the core shaft and the rear short shaft are integrally formed, the inner diameter of the second magnetic isolation ring is equal to the inner diameter of the magnetic steel ring, and the inner diameter of the first magnetic isolation ring is smaller than the inner diameter of the magnetic steel ring.

[0015] Preferably, the core shaft and the rear short shaft are integrally formed, a protrusion is provided at one end of the core shaft facing the front short shaft, and a groove is provided at one end of the front short shaft facing the core shaft, the protrusion is inserted into the groove, and an axial gap is formed between the top surface of the protrusion and the bottom surface of the groove.

[0016] Preferably, the bottom surface of the groove is provided with a magnetic isolation groove which is recessed in a direction away from the protrusion.

[0017] Preferably, the motor shaft further comprises a protective sleeve, which is arranged outside the magnetic steel ring and the magnetic isolation ring, and both the front short shaft and the rear short shaft partially extend into the protective sleeve.

[0018] According to another aspect of the present application, a magnetic levitation motor is provided, comprising a motor shaft, which is the above-mentioned motor shaft.

[0019] The motor shaft provided in the present application includes a front short shaft, a rear short shaft, a core shaft, a front magnetic suspension bearing, a rear magnetic suspension bearing, a magnetic steel ring, a first magnetic isolation ring and a second magnetic isolation ring. The core shaft is arranged between the front short shaft and the rear short shaft, the front magnetic suspension bearing is sleeved on the front short shaft, the rear magnetic suspension bearing is sleeved on the rear short shaft, the magnetic steel ring is sleeved outside the core shaft, the first magnetic isolation ring and the second magnetic isolation ring are sleeved outside the core shaft, the magnetic steel ring is located between the first magnetic isolation ring and the second magnetic isolation ring, the front short shaft and / or the rear short shaft are made of magnetic conductive material, the outer diameters of the first magnetic isolation ring and the second magnetic isolation ring are the same as the outer diameter of the magnetic steel ring, and the inner diameter of the first magnetic isolation ring and / or the second magnetic isolation ring is smaller than the inner diameter of the magnetic steel ring. The motor shaft is provided with magnetic isolation rings at both ends of the magnetic steel ring, thereby blocking the axial magnetic circuit of the magnetic steel ring, reducing the axial magnetic leakage of the annular magnetic steel, and effectively preventing the magnetic steel ring from forming a leakage magnetic circuit in the axial direction. At the same time, since the use of the magnetic isolation ring can effectively limit the axial magnetic leakage of the magnetic steel ring, it is possible to use magnetic conductive materials for the front short shaft and the rear short shaft, and a large number of magnetic lines of force of the magnetic steel ring will not reach the magnetic suspension bearing through the front short shaft and the rear short shaft to cause significant interference to the magnetic field of the magnetic suspension bearing, thereby reducing the control accuracy and control difficulty of the magnetic suspension bearing. The use of magnetic conductive materials for the front short shaft and the rear short shaft can increase the magnetic circuit area of ​​the magnetic suspension bearing, making it difficult for the magnetic circuit of the magnetic suspension bearing rotor to be saturated, thereby effectively improving the bearing output and improving the working performance of the magnetic suspension bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the exploded structure of the motor shaft of an embodiment of the present application;

[0021] Figure 2 It is a cross-sectional structural diagram of the motor shaft of the first embodiment of the present application;

[0022] Figure 3 A cross-sectional structural diagram of a motor shaft according to a second embodiment of the present application;

[0023] Figure 4 Schematic diagram of the magnetic circuit of the magnetic bearing of the motor shaft according to an embodiment of the present application.

[0024] The reference numerals are:

[0025] 1. Front short shaft; 2. Rear short shaft; 3. Core shaft; 4. Front magnetic bearing; 5. Rear magnetic bearing; 6. Magnetic steel ring; 7. First magnetic isolation ring; 8. Second magnetic isolation ring; 9. Annular groove; 10. Ring segment; 11. Groove; 12. Protrusion; 13. Magnetic isolation groove; 14. Sleeve. DETAILED DESCRIPTION

[0026] See also Figures 1 to 4As shown, according to an embodiment of the present application, the motor shaft includes a front short shaft 1, a rear short shaft 2, a core shaft 3, a front magnetic suspension bearing 4, a rear magnetic suspension bearing 5, a magnetic steel ring 6, a first magnetic isolation ring 7 and a second magnetic isolation ring 8, the core shaft 3 is arranged between the front short shaft 1 and the rear short shaft 2, the front magnetic suspension bearing 4 is sleeved on the front short shaft 1, the rear magnetic suspension bearing 5 is sleeved on the rear short shaft 2, the magnetic steel ring 6 is sleeved outside the core shaft 3, the first magnetic isolation ring 7 and the second magnetic isolation ring 8 are sleeved outside the core shaft 3, the magnetic steel ring 6 is located between the first magnetic isolation ring 7 and the second magnetic isolation ring 8, the front short shaft 1 and / or the rear short shaft 2 are made of magnetic conductive material, the outer diameters of the first magnetic isolation ring 7 and the second magnetic isolation ring 8 are the same as the outer diameter of the magnetic steel ring 6, and the inner diameters of the first magnetic isolation ring 7 and / or the second magnetic isolation ring 8 are smaller than the inner diameter of the magnetic steel ring 6.

[0027] The motor shaft is provided with magnetic isolation rings at both ends of the magnetic steel ring 6, thereby blocking the axial magnetic circuit of the magnetic steel ring 6, reducing the axial magnetic leakage of the annular magnetic steel, and effectively preventing the magnetic steel ring 6 from forming a leakage magnetic circuit in the axial direction. At the same time, since the use of the magnetic isolation ring can effectively limit the axial magnetic leakage of the magnetic steel ring 6, it is possible to use magnetic conductive materials for the front short shaft 1 and the rear short shaft 2, and a large number of magnetic lines of force of the magnetic steel ring 6 will not reach the magnetic bearing through the front short shaft 1 and the rear short shaft 2 to cause significant interference to the magnetic field of the magnetic bearing, thereby reducing the control accuracy and control difficulty of the magnetic bearing. The use of magnetic conductive materials for the front short shaft 1 and the rear short shaft 2 can increase the magnetic circuit area of ​​the magnetic bearing, making it difficult for the magnetic circuit of the magnetic bearing rotor to be saturated, thereby effectively improving the bearing output and improving the working performance of the magnetic bearing.

[0028] The core shaft 3 is integrally formed with the front short shaft 1 or the rear short shaft 2, which can ensure the coaxiality of the core shaft 3 and the front short shaft 1 or the rear short shaft 2, reduce the number of parts, reduce processing steps, improve processing efficiency, and reduce processing costs.

[0029] No matter the core shaft 3 and the front short shaft 1 are integrally formed, or the core shaft 3 and the rear short shaft 2 are integrally formed, a split structure can be formed between the front short shaft 1 and the rear short shaft 2, thereby reducing the difficulty of installing the magnetic steel ring 6 and making it more convenient to install the first magnetic isolation ring 7 and the second magnetic isolation ring 8.

[0030] In one embodiment, the core shaft 3 and the rear short shaft 2 are integrally formed, the inner diameter of the second magnetic isolation ring 8 is smaller than the inner diameter of the magnetic steel ring 6, an annular groove 9 is provided at the connection position between the core shaft 3 and the rear short shaft 2, and the second magnetic isolation ring 8 is arranged in the annular groove 9. The second magnetic isolation ring 8 is arranged in the annular groove 9, which can form an axial limit for the second magnetic isolation ring 8, and then the second magnetic isolation ring 8 is used to form an axial limit for the magnetic steel ring 6. Since the outer diameter of the second magnetic isolation ring 8 is equal to the outer diameter of the magnetic steel ring 6, and the inner diameter of the second magnetic isolation ring 8 is smaller than the inner diameter of the magnetic steel ring 6, the radial thickness of the second magnetic isolation ring 8 is greater than the radial thickness of the magnetic steel ring 6. It can not only completely block the magnetic steel ring 6 from the end face, but also block the magnetic lines of force of the magnetic steel ring 6 from the inner circumference of the magnetic steel ring 6, and more effectively prevent the magnetic lines of force of the magnetic steel ring 6 from reaching the rear magnetic suspension bearing 5 through the core shaft 3 and the rear short shaft 2, thereby interfering with the magnetic field of the rear magnetic suspension bearing 5. The axial leakage magnetic isolation effect of the magnetic steel ring 6 is better, making the working performance of the rear magnetic suspension bearing 5 more stable and reliable.

[0031] Since the inner diameter of the second magnetic isolation ring 8 is smaller than the outer diameter of the core shaft 3, in order to facilitate the installation of the second magnetic isolation ring 8 in the annular groove 9, the second magnetic isolation ring 8 includes at least two ring segments 10, and at least two ring segments 10 are combined to form the second magnetic isolation ring 8. Since the second magnetic isolation ring 8 adopts a split structure, it is not affected by the outer diameter of the core shaft 3 and can be directly installed in the annular groove 9. After the installation is completed, the various ring segments 10 can be fixedly connected together. The specific connection method can be bonding, welding or other methods. In addition, since the outer sheath 14 is generally sleeved outside the magnetic steel ring 6, the sleeve 14 can also be used to install and position the second magnetic isolation ring 8. After the various ring segments 10 of the second magnetic isolation ring 8 are installed in the annular groove 9, the sleeve 14 can be sleeved outside the second magnetic isolation ring 8, so that the various ring segments 10 can be tightly combined together to form an annular magnetic isolation structure, which can not only form an effective axial magnetic isolation effect, but also facilitate the installation and fixation of the second magnetic isolation ring 8 in the annular groove 9.

[0032] The ring segments 10 of the second magnetic isolation ring 8 can be two semicircular ring structures or multiple segmented structures. After these segmented structures are combined together, they can form a complete second magnetic isolation ring 8. The ring segments 10 of the second magnetic isolation ring 8 can adopt an equally divided structure. In this way, the structures of the ring segments 10 can be the same, thereby reducing the processing difficulty of the ring segments 10, realizing large-scale batch production, improving production efficiency, and reducing production costs.

[0033] In this embodiment, the inner diameter of the second magnetic isolation ring 8 is the same as the inner diameter of the annular groove 9, thereby effectively ensuring that the inner ring surface of the second magnetic isolation ring 8 fits the bottom wall of the annular groove 9, further improving the stability and reliability of the installation structure of the second magnetic isolation ring 8 on the annular groove 9.

[0034] Preferably, the inner diameter of the first magnetic isolation ring 7 is smaller than or equal to the inner diameter of the magnetic steel ring 6 .

[0035] When the inner diameter of the first magnetic isolation ring 7 is smaller than the inner diameter of the magnetic steel ring 6, the radial thickness of the first magnetic isolation ring 7 is greater than the radial thickness of the magnetic steel ring 6, and the first magnetic isolation ring 7 can play the same effect as the second magnetic isolation ring 8, more effectively avoiding the magnetic steel ring 6 from interfering with the magnetic field of the front magnetic suspension bearing 4, further reducing the control difficulty of the magnetic suspension bearing, and improving the control accuracy of the magnetic suspension bearing. Figure 1 shown.

[0036] When the inner diameter of the first magnetic isolation ring 7 is equal to the inner diameter of the magnetic steel ring 6, the first magnetic isolation ring 7 is integrally formed. At this time, since the inner diameter of the first magnetic isolation ring 7 is equal to the outer diameter of the core shaft 3, it can be directly installed on the core shaft 3 without segmenting the first magnetic isolation ring 7. Figure 2 shown.

[0037] When the inner diameter of the first magnetic isolation ring 7 is smaller than the inner diameter of the magnetic steel ring 6, the first magnetic isolation ring 7 is integrally formed. This is because the first magnetic isolation ring 7 is arranged at one end of the core shaft 3 close to the front short shaft 1. Therefore, at the installation end of the magnetic steel ring 6, the diameter of a section of the core shaft 3 that matches the first magnetic isolation ring 7 can be processed to be smaller to meet the installation requirements of the first magnetic isolation ring 7. Since the core shaft 3 will not hinder the installation of the first magnetic isolation ring 7, the first magnetic isolation ring 7 can be designed as an integral structure to reduce the difficulty of processing and installation of the first magnetic isolation ring 7.

[0038] In other embodiments, the first magnetic isolation ring 7 may also include at least two ring segments 10 , and at least two ring segments 10 are combined to form the first magnetic isolation ring 7 .

[0039] In this embodiment, the magnetic steel ring 6 can be made of neodymium iron boron material and magnetized in parallel radial direction. The first magnetic isolation ring 7 and the second magnetic isolation ring 8 are both tightly fitted to the end surface of the magnetic steel ring 6.

[0040] Preferably, the radial thickness of the second magnetic isolation ring 8 is H1, and the radial thickness of the magnetic steel ring 6 is H2, wherein 1.1≤H1 / H2≤1.4, thereby ensuring that the radial thickness of the second magnetic isolation ring 8 is within a reasonable range, which can ensure that the second magnetic isolation ring 8 has sufficient radial thickness to more effectively block the axial magnetic leakage of the magnetic steel ring 6 and prevent the magnetic lines of force on the magnetic steel ring 6 from reaching the rear magnetic suspension bearing 5 through the core shaft 3; and can also prevent the radial thickness of the second magnetic isolation ring 8 from being too large, resulting in insufficient connection strength between the core shaft 3 and the rear short shaft 2.

[0041] In another embodiment, the core shaft 3 and the front short shaft 1 are integrally formed, the inner diameter of the first magnetic isolation ring 7 is smaller than the inner diameter of the magnetic steel ring 6, an annular groove 9 is provided at the connection position between the core shaft 3 and the front short shaft 1, and the first magnetic isolation ring 7 is provided in the annular groove 9. In this embodiment, the inner diameter of the second magnetic isolation ring 8 can be equal to the inner diameter of the magnetic steel ring 6, or can be smaller than the inner diameter of the magnetic steel ring 6.

[0042] In another embodiment, the core shaft 3 and the rear short shaft 2 are integrally formed, the inner diameter of the second magnetic isolation ring 8 is equal to the inner diameter of the magnetic steel ring 6, and the inner diameter of the first magnetic isolation ring 7 is smaller than the inner diameter of the magnetic steel ring 6. In this embodiment, since the inner diameter of the second magnetic isolation ring 8 is equal to the inner diameter of the magnetic steel ring 6 and is also the same as the outer diameter of the core shaft 3, an integrated structure can be adopted.

[0043] The core shaft 3 is integrally formed with the rear short shaft 2. A protrusion 12 is provided on one end of the core shaft 3 facing the front short shaft 1, and a groove 11 is provided on one end of the front short shaft 1 facing the core shaft 3. The protrusion 12 is inserted into the groove 11, and an axial gap is formed between the top surface of the protrusion 12 and the bottom surface of the groove 11.

[0044] When the inner diameter of the first magnetic isolation ring 7 is equal to the inner diameter of the magnetic steel ring 6, the first magnetic isolation ring 7 located between the magnetic steel ring 6 and the front short axis 1 has a first end face facing the front short axis 1, and the core shaft 3 includes a positioning end face with a protrusion 12, and the first end face is flush with the positioning end face.

[0045] Preferably, the bottom surface of the groove 11 is provided with a magnetic isolation groove 13 which is recessed in a direction away from the protrusion 12. Since the magnetic lines of force of the magnetic steel ring 6 in the axial direction are blocked by the first magnetic isolation ring 7, and the magnetic lines of force located at the center of the core shaft 3 are blocked by the magnetic isolation groove 13, the magnetic lines of force of the magnetic steel ring 6 can be blocked from both the inside and outside of the core shaft 3, which can more effectively prevent the magnetic lines of force of the magnetic steel ring 6 from reaching the front magnetic bearing 4 in the axial direction and causing interference to the magnetic field of the front magnetic bearing 4, further reduce the control difficulty of the front magnetic bearing 4, reduce the influencing factors in the control process of the front magnetic bearing 4, and improve the control accuracy of the front magnetic bearing 4.

[0046] Preferably, the motor shaft further comprises a sheath 14, which is sleeved outside the magnetic steel ring 6 and the magnetic isolation ring, and the front short shaft 1 and the rear short shaft 2 both partially extend into the sheath 14. The above-mentioned sheath 14 is, for example, an alloy sheath.

[0047] The alloy sheath can be made of nickel-based alloy, titanium alloy and other materials, and has an interference fit with the front and rear short shafts, the magnetic steel ring 6 and the magnetic isolation ring. This connection method enables the alloy sheath to transmit mechanical torque between different components of the shaft; when rotating at high speed, the alloy sheath also plays a protective role to ensure the safe operation of the motor shaft. The positioning of the alloy sheath on the shaft is achieved through the corresponding positioning bosses of the front and rear short shafts. The front end face of the alloy sheath should be tightly fitted with the rear end face of the front short shaft boss, and the rear end face of the alloy sheath should be tightly fitted with the front end face of the rear short shaft boss.

[0048] Preferably, there is interference fit between the sleeve and the front short shaft, the rear short shaft, the magnetic isolation ring, and the magnetic steel ring.

[0049] During assembly, first, put the magnetic steel ring 6 and the magnetic isolation ring onto the core shaft 3 in order, and magnetic steel glue can be coated on the inner wall of the magnetic steel ring 6 and the magnetic isolation ring or the outer cylindrical surface of the core shaft 3 to fix the magnetic steel ring 6 and the magnetic isolation ring firmly; then, heat the alloy sheath, and when the sheath 14 expands to a suitable degree, quickly heat-sleeve it onto the rear short shaft 2 to which the magnetic steel ring 6 and the magnetic isolation ring have been fixed, and at the same time, quickly install the front short shaft 1 from the other end of the sheath 14, and quickly fix them coaxially through the centering effect of the concave-convex matching structure formed by the groove 11 of the front short shaft 1 and the protrusion 12 of the rear short shaft 2.

[0050] According to an embodiment of the present application, the magnetic levitation motor includes a motor shaft, which is the above-mentioned motor shaft.

[0051] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0052] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application. The above are only preferred implementations of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present application, and these improvements and variations should also be regarded as the protection scope of the present application.

Claims

1. A motor shaft, characterized in that: The invention comprises a front short shaft (1), a rear short shaft (2), a core shaft (3), a front magnetic suspension bearing (4), a rear magnetic suspension bearing (5), a magnetic steel ring (6), a first magnetic isolation ring (7) and a second magnetic isolation ring (8), wherein the core shaft (3) is arranged between the front short shaft (1) and the rear short shaft (2), the front magnetic suspension bearing (4) is sleeved on the front short shaft (1), the rear magnetic suspension bearing (5) is sleeved on the rear short shaft (2), the magnetic steel ring (6) is sleeved outside the core shaft (3), and the first magnetic isolation ring (7) and the second magnetic isolation ring (8) are arranged between the core shaft (3) and the rear short shaft (2). A magnetic isolation ring (7) and a second magnetic isolation ring (8) are sleeved outside the core shaft (3); the magnetic steel ring (6) is located between the first magnetic isolation ring (7) and the second magnetic isolation ring (8); the front short shaft (1) and / or the rear short shaft (2) are made of magnetic conductive material; the outer diameters of the first magnetic isolation ring (7) and the second magnetic isolation ring (8) are the same as the outer diameter of the magnetic steel ring (6); and the inner diameters of the first magnetic isolation ring (7) and / or the second magnetic isolation ring (8) are smaller than the inner diameter of the magnetic steel ring (6); The core shaft (3) is integrally formed with the front short shaft (1) or the rear short shaft (2); when the core shaft (3) is integrally formed with the rear short shaft (2), the inner diameter of the second magnetic isolation ring (8) is smaller than the inner diameter of the magnetic steel ring (6); an annular groove (9) is provided at the connection position between the core shaft (3) and the rear short shaft (2), and the second magnetic isolation ring (8) is provided in the annular groove (9); The core shaft (3) and the rear short shaft (2) are integrally formed, and a protrusion (12) is provided on one end of the core shaft (3) facing the front short shaft (1), and a groove (11) is provided on one end of the front short shaft (1) facing the core shaft (3). The protrusion (12) is inserted into the groove (11), and an axial gap is formed between the top surface of the protrusion (12) and the bottom surface of the groove (11); the bottom surface of the groove (11) is provided with a magnetic isolation groove (13) which is recessed in a direction away from the protrusion (12), and the magnetic lines of force on the inner circumference of the second magnetic isolation ring (8) are blocked by the second magnetic isolation ring (8), and the magnetic lines of force located at the center of the core shaft (3) are blocked by the magnetic isolation groove (13).

2. The motor shaft according to claim 1, characterized in that: The second magnetic isolation ring (8) comprises at least two ring segments (10), and the at least two ring segments (10) are combined to form the second magnetic isolation ring (8).

3. The motor shaft according to claim 1, characterized in that: The inner diameter of the first magnetic isolation ring (7) is smaller than or equal to the inner diameter of the magnetic steel ring (6).

4. The motor shaft according to claim 3, characterized in that: The first magnetic isolation ring (7) is integrally formed, or the first magnetic isolation ring (7) comprises at least two ring segments (10), and the at least two ring segments (10) are combined to form the first magnetic isolation ring (7).

5. The motor shaft according to claim 1, characterized in that: The radial thickness of the second magnetic isolation ring (8) is H1, and the radial thickness of the magnetic steel ring (6) is H2, wherein 1.1≤H1 / H2≤1.

4.

6. The motor shaft according to claim 1, characterized in that: The core shaft (3) and the front short shaft (1) are integrally formed, the inner diameter of the first magnetic isolation ring (7) is smaller than the inner diameter of the magnetic steel ring (6), an annular groove (9) is provided at the connection position between the core shaft (3) and the front short shaft (1), and the first magnetic isolation ring (7) is arranged in the annular groove (9).

7. The motor shaft according to claim 1, characterized in that: The core shaft (3) and the rear short shaft (2) are integrally formed, the inner diameter of the second magnetic isolation ring (8) is equal to the inner diameter of the magnetic steel ring (6), and the inner diameter of the first magnetic isolation ring (7) is smaller than the inner diameter of the magnetic steel ring (6).

8. The motor shaft according to claim 1, characterized in that: The motor shaft further comprises a protective sleeve (14), wherein the protective sleeve (14) is sleeved outside the magnetic steel ring (6) and the magnetic isolation ring, and the front short shaft (1) and the rear short shaft (2) both partially extend into the protective sleeve (14).

9. A magnetic levitation motor, comprising a motor shaft, characterized in that: The motor shaft is the motor shaft according to any one of claims 1 to 8.

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