A magnetic levitation flywheel

Abstract

This invention discloses a magnetically levitated flywheel, belonging to the technical field of actuators for spacecraft attitude control systems. It includes a sealed housing with an internal vacuum chamber. Inside the vacuum chamber, a flywheel body, a motor, a mounting shaft, and a magnetic levitation bearing assembly. The magnetic levitation bearing assembly includes radial and axial magnetic levitation bearings. The mounting shaft has a stator portion of the radial magnetic levitation bearing, and a rotor portion of the radial magnetic levitation bearing is mounted on a radial rotor mounting seat on the flywheel. The flywheel rim includes a magnetic levitation section and a motor drive section. The top / bottom surfaces of the magnetic levitation section have the rotor portion of the axial magnetic levitation bearing, and the upper / lower surfaces of the magnetic levitation section have the stator portion of the axial magnetic levitation bearing. The bottom surface of the motor drive section has an outer rotor portion and an inner rotor portion of the motor, with the stator portion of the motor located between them. The axial magnetic levitation bearing is positioned at the flywheel rim, ensuring stability at the rim, reducing the axial length of the mounting shaft, and increasing the upper speed limit.

Description

Technical Field

[0001] This invention relates to the field of spacecraft attitude control system actuators, and in particular to a magnetically levitated flywheel. Background Technology

[0002] Attitude control actuators for spacecraft such as satellites, Earth observation platforms, spacecraft, and space telescopes require small size, light weight, long lifespan, low power consumption, and high reliability. Currently, flywheels, which serve as actuators in spacecraft attitude control systems, are generally still supported by mechanical bearings. This fundamentally limits the increase in flywheel speed, and mechanical bearings suffer from problems such as mechanical wear, uncontrollable unbalanced vibration, and large zero-crossing friction torque, seriously affecting the lifespan of the flywheel and the accuracy and stability of spacecraft attitude control. Therefore, magnetic levitation flywheels supported by magnetic bearings have gradually been proposed in the market to increase the upper limit of speed while reducing the wear of mechanical bearing supports. Current magnetic levitation flywheels typically have two radial magnetic levitation bearings on the vertical shaft to provide radial translation and radial deflection motion, and two axial magnetic levitation bearings in the middle of the flywheel body to provide axial translational motion, such as the "five-degree-of-freedom magnetic levitation flywheel" disclosed in patent number "201811414823.3". When it is necessary to increase the rotational momentum output of a flywheel, the following methods are usually used: 1. Increase the radial length of the flywheel body or the weight ratio of the rim to increase the rotational momentum of the rim. However, this method will reduce the stability of the flywheel body rim. 2. Increase the span of the two radial magnetic bearings to output sufficient torque and increase the rotational momentum. However, this will make the axial length of the mounting vertical shaft longer, reduce the mode, limit the speed increase, and aggravate vibration. Summary of the Invention

[0003] The purpose of this invention is to solve the above-mentioned technical problems and provide a magnetic levitation flywheel. By setting the axial magnetic levitation bearing at the rim, not only can the stability at the rim be guaranteed, but the radial length of the flywheel body or the weight ratio of the rim can be increased. At the same time, the axial length of the mounting vertical shaft can be reduced, the mode is improved, the upper limit of the rotational speed is increased, and the vibration of the flywheel body during rotation is reduced.

[0004] To achieve the above objectives, the present invention provides the following solution: The present invention discloses a magnetic levitation flywheel, comprising a sealed housing with an internal vacuum chamber, wherein the vacuum chamber contains a flywheel body, a motor, a fixedly mounted vertical shaft, and a magnetic levitation bearing assembly for levitizing the flywheel body. The magnetic levitation bearing assembly includes a radial magnetic levitation bearing and an axial magnetic levitation bearing. The mounting vertical shaft has a radial stator mounting area for mounting the stator portion of the radial magnetic levitation bearing. The flywheel body's disc has a central hole for fitting onto the mounting vertical shaft, and the central hole coaxially fixes a rotor portion for mounting the radial magnetic levitation bearing. The radial rotor mounting base includes a flywheel body rim comprising a magnetic levitation section and a motor drive section. The top and bottom surfaces of the magnetic levitation section are provided with an upper axial rotor mounting area and a lower axial rotor mounting area for mounting the rotor portion of the axial magnetic levitation bearing. The stator portion of the axial magnetic levitation bearing is provided above the upper axial rotor mounting area and below the lower axial rotor mounting area. The bottom surface of the motor drive section is provided with a motor rotor mounting groove. The outer rotor portion and the inner rotor portion of the motor are mounted in the motor rotor mounting groove. A drive distance is reserved between the outer rotor portion and the inner rotor portion for the stator portion of the motor to extend into.

[0005] Preferably, an upper protective bearing and a lower protective bearing are respectively installed above and below the radial stator mounting area on the mounting vertical shaft.

[0006] The radial rotor mounting base is provided with an inverted L-shaped protective sleeve and a regular L-shaped lower protective sleeve at its top and bottom, respectively. There is a radial protective gap between the inner wall of the vertical section of the inverted L-shaped protective sleeve and the side wall of the upper protective bearing, and between the inner wall of the vertical section of the regular L-shaped lower protective sleeve and the side wall of the lower protective bearing. There is an axial protective gap between the bottom surface of the horizontal section of the inverted L-shaped protective sleeve and the top surface of the upper protective bearing, and between the bottom surface of the horizontal section of the regular L-shaped lower protective sleeve and the top surface of the lower protective bearing.

[0007] Preferably, the axial protection gap is 0.8 to 1.0 mm, and the radial protection gap is 0.1 to 0.3 mm.

[0008] Preferably, a T-shaped positioning sleeve is fixed to the bottom of the flywheel body's disc. The T-shaped positioning sleeve includes a vertical sleeve and an annular edge located at the top of the vertical sleeve. Several displacement sensors are arranged circumferentially around the vertical sleeve. The displacement sensors include an axial probe facing the annular edge and a radial probe facing the vertical sleeve. The axial probe is located below the annular edge.

[0009] Preferably, the motor drive section is located between the magnetic levitation section and the wheel, and the thickness of the motor drive section is greater than the thickness of the magnetic levitation section, which in turn is greater than the thickness of the wheel.

[0010] Preferably, the end of the magnetic levitation section away from the motor drive section is provided with a specific gravity increasing section.

[0011] Preferably, the flywheel body is made of high-strength short fiber reinforced resin material.

[0012] Preferably, the sealing housing includes a base and a sealing cover, the mounting vertical shaft is fixed on the base, and the inner wall of the top of the sealing cover is provided with a positioning groove for the top of the mounting vertical shaft to be inserted into, and the sealing cover is mounted on the base.

[0013] Preferably, the base is provided with an axial stator mounting seat for mounting the stator portion of the axial magnetic levitation bearing, the axial stator mounting seat is fixed on the base, and the top of the axial stator mounting seat is in contact with the inner wall of the top of the sealing cover.

[0014] Preferably, the sidewall of the sealing cover and the sidewall of the axial stator mounting base are fitted together.

[0015] The present invention achieves the following technical effects compared to the prior art:

[0016] 1. Compared to traditional magnetic levitation flywheels where the axial magnetic levitation bearing is located at the center of the flywheel disc, this invention moves the axial magnetic levitation bearing to the rim of the flywheel. This ensures more stable rotation of the flywheel as a whole, reduces vibration, and allows for a more appropriate increase in the flywheel disc diameter compared to traditional magnetic levitation flywheels. This increases rotational momentum output, or increases the rim thickness while reducing the axial dimension of the disc, concentrating more rotor mass at the rim. This effectively increases the rotor's polar moment of inertia / mass ratio and reduces flywheel weight. Furthermore, moving the axial magnetic levitation bearing to the rim also reduces the axial length of the mounting vertical shaft, increases the modal capacity, and raises the upper limit of rotational speed. The component layout is also more rational and compact.

[0017] 2. In this invention, the thickness of the motor drive section is greater than the thickness of the magnetic levitation section, and the thickness of the magnetic levitation section is greater than the thickness of the wheel disk. This concentrates more of the flywheel's mass at the rim, effectively increasing the rotor's polar moment of inertia / mass ratio and reducing the flywheel's weight.

[0018] 3. In this invention, a specific gravity enhancement section is added to the end of the magnetic levitation section away from the motor drive section 2, which further concentrates the mass at the rim and adjusts the center of gravity towards the rim, maximizing the utilization rate of the stability brought about by the arrangement of the axial magnetic levitation bearings at the rim.

[0019] 4. In this invention, the flywheel body is made of high-strength fiber short filament reinforced resin material. The specific gravity of high-strength fiber short filament reinforced resin material is much smaller than that of steel, but its tensile strength is much greater than that of steel.

[0020] 5. The magnetic levitation bearing assembly in this invention includes only one radial magnetic levitation bearing. Since only one radial magnetic levitation bearing is needed to control the rotor's translation, the axial dimension of the mounting vertical shaft 4 is effectively reduced, its first-order natural mode frequency is significantly increased, the vibration introduced by the first-order natural mode of the stator shaft is mitigated, the flywheel vibration level is reduced, and the impact load resistance and reliability of the launching section flywheel are improved. The reduction in axial dimension allows more of the rotor's mass to be concentrated at the rim, effectively increasing the rotor's polar moment of inertia / mass ratio, reducing the flywheel weight, and resulting in a more rational and compact assembly layout. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A simplified side-view cross-sectional diagram of a magnetic levitation flywheel;

[0023] Figure 2 This is a magnified view of a portion of the radial magnetic levitation bearing.

[0024] Figure 3 This is a magnified view of a portion of the axial magnetic levitation bearing.

[0025] Figure 4 A simplified side cross-sectional view of the magnetic levitation flywheel with an added specific gravity section;

[0026] Figure 5 This is a simplified top-view cross-sectional diagram of an axial magnetic levitation bearing.

[0027] Explanation of reference numerals in the attached drawings: 1. Base; 2. Sealing cover; 3. Flywheel body; 4. Mounting vertical shaft; 5. Stator part of radial magnetic levitation bearing; 6. Rotor part of radial magnetic levitation bearing; 7. Radial rotor mounting seat; 8. Axial stator mounting seat; 9. Rotor part of upper axial magnetic levitation bearing; 10. Stator part of upper axial magnetic levitation bearing; 11. Rotor part of lower axial magnetic levitation bearing; 12. Stator part of lower axial magnetic levitation bearing; 13. Outer rotor part of motor; 14. Inner rotor part of motor; 15. Stator part of motor; 16. Upper protective bearing; 17. Lower protective bearing; 18. T-shaped positioning sleeve; 19. Displacement sensor; 20. Axial probe; 21. Radial probe; 22. Magnetic levitation section; 23. Motor drive section; 24. Specific gravity enhancement section; 25. Radial protection gap; 26. Axial protection gap; 27. Axial magnetic levitation stator core; 28. Axial magnetic levitation bearing excitation coil; 29. ​​Permanent magnet; 30. Outer magnetic ring; 31. Radial magnetic levitation bearing rotor core; 32. Magnetic isolation ring; 33. Air gap; 34. Radial magnetic levitation bearing excitation coil; 35. Radial magnetic levitation bearing stator core; 36. Radial magnetic levitation bearing mounting base; 37. Motor cup-shaped stator; 38. Motor outer rotor pressure plate; 39. Outer rotor stack; 40. Magnet; 41. Inner rotor stack; 42. Inner rotor pressure plate; 43. Magnetic gap. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] This embodiment provides a magnetically levitated flywheel, such as Figures 1 to 4As shown, the device includes a sealed housing, within which a vacuum chamber is provided. Within the vacuum chamber, a flywheel body 3, a motor, a fixed mounting shaft 4, and a magnetic levitation bearing assembly for suspending the flywheel body 3 are housed. The magnetic levitation bearing assembly includes radial magnetic levitation bearings and axial magnetic levitation bearings; the axial magnetic levitation bearings include an upper axial magnetic levitation bearing and a lower axial magnetic levitation bearing. The flywheel body 3 has a central hole on its disc for fitting onto the mounting shaft 4. A radial rotor mounting seat 7 is coaxially fixed to the central hole. The rotor portion 6 of the radial magnetic levitation bearing is mounted on the radial rotor mounting seat 7. The mounting shaft 4 has a radial stator mounting area, and the stator portion 5 of the radial magnetic levitation bearing is mounted in the radial stator mounting area. The rotor portion 6 and the stator portion 5 of the radial magnetic levitation bearing correspond to each other. The flywheel body 3 has a rim comprising a magnetic levitation section 22 and a motor drive section 23. The top and bottom surfaces of the magnetic levitation section 22 are respectively provided with an upper axial rotor mounting area and a lower axial rotor mounting area. The rotor portion 9 of the upper axial magnetic levitation bearing is mounted on the upper axial rotor mounting area. The stator portion 10 of the upper axial magnetic levitation bearing is located above the upper axial rotor mounting area and corresponds to the rotor portion 9. The rotor portion 11 of the lower axial magnetic levitation bearing is mounted on the lower axial rotor mounting area. The stator portion 12 of the lower axial magnetic levitation bearing is located below the lower axial rotor mounting area and corresponds to the rotor portion 11. The bottom surface of the motor drive section 23 is provided with a motor rotor mounting groove. The outer rotor portion 13 and the inner rotor portion 14 of the motor are mounted in the motor rotor mounting groove. A drive gap is reserved between the outer rotor portion 13 and the inner rotor portion 14 of the motor. The stator portion 15 of the motor extends into the drive gap and is located between the outer rotor portion 13 and the inner rotor portion 14 of the motor.

[0030] Working principle: When the motor is energized, the magnetic force generated by the stator 15, outer rotor 13, and inner rotor 14 of the motor drives the drive section 23 of the drive motor to rotate, which in turn drives the entire rim to rotate, thus driving the entire flywheel body 3. Under the action of radial and axial magnetic levitation bearings, the flywheel body 3 can rotate stably. Decreasing or increasing the speed of the flywheel body 3 can be used to adjust the attitude of the spacecraft. Compared with traditional magnetic levitation flywheels that place the axial magnetic levitation bearing in the center of the flywheel body 3, this magnetic levitation flywheel moves the axial magnetic levitation bearing to the rim of the flywheel body 3, which can ensure more stable rotation of the flywheel body 3 and reduce the degree of vibration. Therefore, compared with traditional magnetic levitation flywheels, the diameter of the flywheel body 3 can be relatively increased, improving the rotational momentum output. At the same time, moving the axial magnetic levitation bearing to the rim of the flywheel body 3 also reduces the axial length of the mounting vertical shaft 4, increasing the mode and raising the upper limit of the speed.

[0031] Preferably, the magnetic levitation bearing assembly includes only one radial magnetic levitation bearing. Since only one radial magnetic levitation bearing is needed to control the rotor's translation, the axial dimension of the mounting vertical shaft 4 is effectively reduced, its first-order natural mode frequency is significantly increased, the vibration introduced by the first-order natural mode of the stator shaft is mitigated, the flywheel vibration level is reduced, and the impact load resistance and reliability of the launching section flywheel are improved. The reduction in axial dimension allows more of the rotor's mass to be concentrated at the rim, effectively increasing the rotor's polar moment of inertia / mass ratio, reducing the flywheel weight, and resulting in a more rational and compact assembly layout.

[0032] In this embodiment, as Figures 1 to 5 As shown, an upper protective bearing 16 and a lower protective bearing 17 are mounted on the vertical shaft 4. The upper protective bearing 16 is located above the radial stator mounting area, and the lower protective bearing 17 is located below the radial stator mounting area. The top and bottom of the radial rotor mounting base 7 are respectively provided with an inverted L-shaped protective sleeve and a regular L-shaped lower protective sleeve. A radial protective gap 25 is provided between the inner wall of the vertical section of the inverted L-shaped protective sleeve and the side wall of the upper protective bearing 16, and an axial protective gap 26 is provided between the bottom surface of the horizontal section of the inverted L-shaped protective sleeve and the top surface of the upper protective bearing 16. Similarly, a radial protective gap 25 is provided between the inner wall of the vertical section of the regular L-shaped lower protective sleeve and the side wall of the lower protective bearing 17, and an axial protective gap 26 is provided between the bottom surface of the horizontal section of the regular L-shaped lower protective sleeve and the top surface of the lower protective bearing 17. The upper protective bearing 16 and the lower protective bearing 17 are mechanical bearings.

[0033] Furthermore, in this embodiment, as Figures 1 to 5 As shown, the axial protection gap 26 is 0.8 to 1.0 mm, and the radial protection gap 25 is 0.1 to 0.3 mm.

[0034] In this embodiment, as Figures 1 to 5 As shown, a T-shaped positioning sleeve 18 is fixed to the bottom of the flywheel body 3's disc. The T-shaped positioning sleeve 18 includes a vertical sleeve and an annular edge located at the top of the vertical sleeve. Several displacement sensors 19 are arranged circumferentially around the vertical sleeve. The displacement sensors 19 include axial probes 20 and radial probes 21. The axial probes 20 are located below the annular edge and face the annular edge, while the radial probes 21 face the vertical sleeve. The axial probes 20 detect three generalized displacements: axial translation and two radial rotations. The radial probes 21 detect two radial translational displacements. The housing of the displacement sensors 19 can shield electromagnetic interference, and the internal circuitry extracts the displacement information of the flywheel body 3. The number of displacement sensors 19 is not limited, but at least four are provided, with four arranged in a cross shape around the T-shaped positioning sleeve 18.

[0035] In this embodiment, as Figures 1 to 5As shown, the motor drive section 23 is located between the magnetic levitation section 22 and the wheel disk of the flywheel body 3. The thickness of the motor drive section 23 is greater than the thickness of the magnetic levitation section 22, and the thickness of the magnetic levitation section 22 is greater than the thickness of the wheel disk. This concentrates more of the mass of the flywheel body 3 at the rim, effectively increasing the polar moment of inertia / mass ratio of the rotor and reducing the weight of the flywheel body 3.

[0036] Furthermore, in this embodiment, as Figures 1 to 5 As shown, the magnetic levitation section 22 is provided with a specific gravity enhancement section 24 at the end away from the motor drive section 23, which further concentrates the mass at the rim and adjusts the center of gravity towards the rim, maximizing the utilization of the stability brought by the arrangement of the axial magnetic levitation bearings at the rim.

[0037] In this embodiment, as Figures 1 to 5 As shown, the flywheel body 3 is made of high-strength fiber short-filament reinforced resin material. The flywheel body 3 made of this material has a much lower specific gravity than steel, but a much higher tensile strength. Of course, the flywheel body 3 can still be made of steel; it is not limited to using high-strength fiber short-filament reinforced resin material. That is, the flywheel body 3 can also be made of other materials with high tensile strength as needed.

[0038] In this embodiment, as Figures 1 to 5 As shown, the sealing housing includes a base 1 and a sealing cover 2. A mounting shaft 4 is fixed to the base 1, which can be achieved by welding or bolting. A positioning groove is provided on the inner wall of the top of the sealing cover 2. The sealing cover 2 is inserted into the top of the mounting shaft 4 through the positioning groove to achieve positioning. The sealing cover 2 is mounted on the base 1. Preferably, the sealing cover 2 is welded to the base 1 and sealed to ensure that a vacuum chamber can be formed between the sealing cover 2 and the base 1. The displacement sensor 19 can be fixed to the base 1 via a bracket.

[0039] Furthermore, in this embodiment, as Figures 1 to 5 As shown, an axial stator mounting seat 8 is provided on the base 1. The axial stator mounting seat 8 is fixed to the base 1 by bolt connection or welding. The stator part 10 of the upper axial magnetic levitation bearing and the stator part 12 of the lower axial magnetic levitation bearing are both mounted on the axial stator mounting seat 8. The top of the axial stator mounting seat 8 is in contact with the inner wall of the top of the sealing cover 2, which can provide a certain degree of support to the sealing cover 2 and reduce the vibration that may be generated by the sealing cover 2.

[0040] Furthermore, in this embodiment, as Figures 1 to 5 As shown, the side wall of the sealing cover 2 and the side wall of the axial stator mounting seat 8 are also in contact.

[0041] In this embodiment, as Figures 1 to 5As shown, the axial magnetic levitation bearing is a purely electrically excited magnetic levitation bearing, mainly consisting of the rotor part of the axial magnetic levitation bearing, four identical non-magnetically coupled axial magnetic levitation stator cores 27, and axial magnetic levitation bearing excitation coils 28. The rotor part of the axial magnetic levitation bearing is connected to the magnetic levitation section 22 of the wheel rim and is the rotating part, while the axial magnetic levitation stator cores 27 and axial magnetic levitation bearing excitation coils 28 are mounted on the axial stator mounting base 8 and are the stationary parts.

[0042] In this embodiment, as Figures 1 to 5 As shown, the radial magnetic levitation bearing is a permanent magnet biased, electromagnetically controlled active magnetic levitation bearing, mainly composed of a permanent magnet 29, an outer magnetic ring 30, a radial magnetic levitation bearing rotor core 31, a magnetic isolation ring 32, a radial magnetic levitation bearing excitation coil 34, a radial magnetic levitation bearing stator core 35, and a radial magnetic levitation bearing mounting base 36. The permanent magnet 29, outer magnetic ring 30, radial magnetic levitation bearing rotor core 31, and magnetic isolation ring 32 are the rotating parts, while the radial magnetic levitation bearing excitation coil 34, radial magnetic levitation bearing stator core 35, and radial magnetic levitation bearing mounting base 36 are the stationary parts. An air gap 33 exists between the radial magnetic levitation bearing rotor core 31 and the radial magnetic levitation bearing stator core 35.

[0043] In this embodiment, as Figures 1 to 5 As shown, the motor consists of a cup-shaped stator 37, an outer rotor pressure plate 38, an outer rotor stack 39, magnets 40, an inner rotor stack 41, and an inner rotor pressure plate 42. The cup-shaped stator 37 is the stationary part of the motor, while the rest are rotating parts. A magnetic gap 43 exists between the inner rotor stack 41 and the inner rotor pressure plate 42. The motor is generally a highly reliable and efficient brushless DC motor, but a permanent magnet synchronous motor can also be used.

[0044] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A magnetically levitated flywheel, characterized in that, The device includes a sealed housing with an internal vacuum chamber. Inside the vacuum chamber are a flywheel, a motor, a fixed mounting shaft, and a magnetic levitation bearing assembly for suspending the flywheel. The magnetic levitation bearing assembly includes a radial magnetic levitation bearing and an axial magnetic levitation bearing. The mounting shaft has a radial stator mounting area for mounting the stator portion of the radial magnetic levitation bearing. The flywheel disc has a central hole for fitting onto the mounting shaft. A radial rotor mounting seat for mounting the rotor portion of the radial magnetic levitation bearing is coaxially fixed to the central hole. The flywheel rim includes a magnetic levitation section and a motor drive section. The top and bottom surfaces of the magnetic levitation section have mounting surfaces for... The rotor portion of the axial magnetic levitation bearing has an upper axial rotor mounting area and a lower axial rotor mounting area. The stator portion of the axial magnetic levitation bearing is located above the upper axial rotor mounting area and below the lower axial rotor mounting area. The bottom surface of the motor drive section has a motor rotor mounting groove. The outer rotor portion and the inner rotor portion of the motor are installed in the motor rotor mounting groove. A drive gap is reserved between the outer rotor portion and the inner rotor portion for the stator portion of the motor to extend into. The motor drive section is located between the magnetic levitation section and the wheel. The thickness of the motor drive section is greater than the thickness of the magnetic levitation section, and the thickness of the magnetic levitation section is greater than the thickness of the wheel.

2. The magnetic levitation flywheel according to claim 1, characterized in that, An upper protective bearing and a lower protective bearing are respectively installed on the vertical mounting shaft above and below the radial stator mounting area. The top and bottom of the radial rotor mounting base are respectively provided with an inverted L-shaped protective sleeve and a regular L-shaped lower protective sleeve. There is a radial protective gap between the inner wall of the vertical section of the inverted L-shaped protective sleeve and the side wall of the upper protective bearing, and between the inner wall of the vertical section of the regular L-shaped lower protective sleeve and the side wall of the lower protective bearing. There is an axial protective gap between the bottom surface of the horizontal section of the inverted L-shaped protective sleeve and the top surface of the upper protective bearing, and between the bottom surface of the horizontal section of the regular L-shaped lower protective sleeve and the top surface of the lower protective bearing.

3. A magnetic levitation flywheel according to claim 2, characterized in that, The axial protection gap is 0.8–1.0 mm, and the radial protection gap is 0.1–0.3 mm.

4. A magnetic levitation flywheel according to claim 1, characterized in that, The bottom of the flywheel body's disc is fixed with a T-shaped positioning sleeve. The T-shaped positioning sleeve includes a vertical sleeve and an annular edge located at the top of the vertical sleeve. Several displacement sensors are arranged circumferentially around the vertical sleeve. The displacement sensors include an axial probe facing the annular edge and a radial probe facing the vertical sleeve. The axial probe is located below the annular edge.

5. A magnetic levitation flywheel according to claim 1, characterized in that, The magnetic levitation section is provided with a specific gravity increasing section at the end away from the motor drive section.

6. A magnetic levitation flywheel according to claim 5, characterized in that, The flywheel body is made of high-strength short fiber reinforced resin material.

7. A magnetic levitation flywheel according to any one of claims 1-6, characterized in that, The sealing housing includes a base and a sealing cover. The mounting vertical shaft is fixed on the base. The inner wall of the top of the sealing cover is provided with a positioning groove for the top of the mounting vertical shaft to be inserted. The sealing cover is mounted on the base.

8. A magnetic levitation flywheel according to claim 7, characterized in that, The base is provided with an axial stator mounting seat for mounting the stator portion of the axial magnetic levitation bearing. The axial stator mounting seat is fixed on the base, and the top of the axial stator mounting seat is in contact with the inner wall of the top of the sealing cover.

9. A magnetic levitation flywheel according to claim 8, characterized in that, The sidewall of the sealing cover is in contact with the sidewall of the axial stator mounting seat.

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