Magnetic levitation bearing structure, motor

Abstract

The present invention provides a magnetic levitation bearing structure and a motor. The magnetic levitation bearing structure includes: a bearing housing sleeved on a rotating shaft assembly; a radial position adjustment assembly for controlling and adjusting the radial displacement of the rotating shaft assembly; an axial position adjustment assembly for controlling and adjusting the axial displacement of the rotating shaft assembly. The radial position adjustment assembly and the axial position adjustment assembly are sleeved on the rotating shaft assembly along the axial direction of the rotating shaft assembly. An axial working air gap is formed between one side of the axial position adjustment assembly facing away from the radial position adjustment assembly and a thrust disk of the rotating shaft assembly. A magnetic steel has an N pole and an S pole, and is clamped between the radial position adjustment assembly and the axial position adjustment assembly with the N pole facing the axial working air gap side. According to the present invention, the magnetic force lines emitted by the N pole of the magnetic steel can pass through the axial working air gap along a shorter path, thereby greatly reducing the magnetic leakage phenomenon caused by the magnetic force line passing path process.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic levitation bearing design, and particularly relates to a magnetic levitation bearing structure and a motor. Background Art

[0002] A magnetic levitation bearing (hereinafter referred to as a magnetic bearing) uses electromagnetic force to suspend a rotor in the air, so that there is no mechanical contact between the rotor and the stator, reducing wear and tear and improving efficiency. A hybrid radial bearing is a common magnetic levitation bearing, which uses magnetic steel (such as a permanent magnet) to generate a bias magnetic field, and the magnetic field generated by energizing the coil only provides a dynamic magnetic field to balance the load or external interference, which can greatly reduce the power loss generated by the bias magnetic current of the system, save energy, and reduce the volume of the power amplifier radiator. The number of ampere-turns required for the electromagnet (i.e., the coil) of the hybrid magnetic levitation bearing is only half of that of the active magnetic levitation bearing, reducing the volume of the magnetic bearing and the weight of the magnetic bearing. This magnetic bearing has broad application prospects in magnetic levitation motors, high-speed flywheel energy storage devices, etc.

[0003] Figure 8 A hybrid radial bearing in the related art is shown, which mainly consists of an iron core a, a radial ring b, a magnetic conduction ring c, a magnetic steel d, a coil e, a housing f, etc. This product can achieve radial control of the bearing rotor, but at the same time has the following disadvantages: only the iron core in the radial component plays a radial control effect, and the magnetic conduction ring does not play a control role, resulting in low utilization rate of the magnetic steel.

[0004] In order to overcome Figure 8 the deficiencies of the hybrid radial bearing shown in Summary of the Invention

[0005] Therefore, the present invention provides a magnetic levitation bearing structure and a motor to overcome the deficiencies that the magnetic leakage phenomenon caused by the too long magnetic conduction path between the N pole of the magnetic steel and the axial working air gap in the prior art increases the volume of the magnetic bearing or raises the cost.

[0006] To solve the above problems, the present invention provides a magnetic levitation bearing structure, including:

[0007] A bearing housing, sleeved on a rotating shaft assembly;

[0008] A radial position adjustment assembly, installed inside the bearing housing, for controlling and adjusting the radial displacement of the rotating shaft assembly;

[0009] An axial position adjustment assembly, installed inside the bearing housing, for controlling and adjusting the axial displacement of the rotating shaft assembly. The radial position adjustment assembly and the axial position adjustment assembly are sleeved on the rotating shaft assembly along the axial direction of the rotating shaft assembly. An axial working air gap is formed between one side of the axial position adjustment assembly facing away from the radial position adjustment assembly and a thrust disc of the rotating shaft assembly;

[0010] A permanent magnet, having an N pole and an S pole, is clamped between the radial position adjustment assembly and the axial position adjustment assembly, and the N pole faces the side of the axial working air gap.

[0011] In some embodiments,

[0012] The axial position adjustment assembly includes an axial stator core. A first annular air gap is formed between a first axial hole of the axial stator core and the rotating shaft assembly. The radial position adjustment assembly includes a radial stator core. A radial working air gap is formed between a second axial hole of the radial stator core and the rotating shaft assembly. The radial width of the first annular air gap is smaller than the radial width of the radial working air gap.

[0013] In some embodiments,

[0014] The radial position adjustment assembly further includes a radial magnetic conductive ring. A bearing chamber is formed on the bearing housing. The radial stator core is clamped between the axial bottom wall of the bearing chamber and the radial magnetic conductive ring.

[0015] In some embodiments,

[0016] The radial magnetic conductive ring is threadedly connected to the peripheral wall of the bearing chamber.

[0017] In some embodiments,

[0018] The rotating shaft assembly further includes a rotating shaft. A radial rotor core is sleeved on the outer peripheral wall of the rotating shaft corresponding to the radial stator core. The radial working air gap is formed between the radial rotor core and the radial stator core.

[0019] In some embodiments,

[0020] The thrust disc is sleeved on the rotating shaft and can axially position the radial rotor core.

[0021] In some embodiments,

[0022] A magnetic conduction transition collar is further clamped between the thrust disc and the radial rotor iron core, and a first annular air gap is formed between the magnetic conduction transition collar and the axial stator iron core.

[0023] In some embodiments,

[0024] The axial position regulation component further includes an axial control coil, and the axial control coil is arranged on one side of the axial stator iron core facing the thrust disc through a coil skeleton.

[0025] In some embodiments,

[0026] The coil skeleton has an annular groove and a connecting protrusion that is cooperatively connected with a groove on the axial stator iron core, and the annular groove is used for installing the axial control coil.

[0027] The present invention also provides a motor, including the above magnetic suspension bearing structure.

[0028] For a magnetic suspension bearing structure and a motor provided by the present invention, when the N pole of the permanent magnet faces the side of the axial working air gap, the magnetic force lines emitted by the N pole of the permanent magnet can pass through the axial working air gap along a shorter path, so that the magnetic leakage phenomenon caused by the magnetic force line passing path can be greatly reduced. Therefore, it is beneficial to select a smaller volume or a lower grade of permanent magnet to achieve the same axial biasing purpose, and further make the structure of the magnetic suspension bearing more compact and the manufacturing cost reduced. Description of the Drawings

[0029] Figure 1 is a schematic internal structure diagram (cross-section) of the magnetic suspension bearing structure according to an embodiment of the present invention;

[0030] Figure 2 is Figure 1 a schematic structural diagram of the radial position regulation component in

[0031] Figure 3 is Figure 1 a schematic structural diagram of the axial position regulation component in

[0032] Figure 4 is Figure 1 the path of the magnetic force lines of the axial biasing magnetic field (the dotted line path in the figure) and the axial control magnetic field (the solid line path in the figure) when a current in a first direction is passed through the axial control coil in

[0033] Figure 5 is Figure 1 the path of the magnetic force lines of the axial biasing magnetic field (the dotted line path in the figure) and the axial control magnetic field (the solid line path in the figure) when a current in a second direction (opposite to the first direction) is passed through the axial control coil in

[0034] Figure 6 For Figure 1 the paths of the magnetic force lines of the radially offset magnetic field (the dashed-line path in the figure) and the radially control magnetic field (the solid-line path in the figure);

[0035] Figure 7 is a schematic diagram of the internal structure of the motor according to an embodiment of the present invention;

[0036] Figure 8 is a schematic diagram of the internal structure of a magnetic suspension bearing in the prior art.

[0037] The reference numerals are shown as:

[0038] 1, bearing housing; 11, assembly positioning hole; 2, radial position regulation component; 21, radial stator core; 22, radial magnetic conduction ring; 23, radial control coil; 3, axial position regulation component; 31, axial stator core; 32, axial control coil; 33, coil skeleton; 331, connecting protrusion; 332, annular groove; 4, permanent magnet; 101, thrust plate; 102, rotating shaft; 103, radial rotor core; 104, magnetic conduction transition sleeve ring; 201, axial working air gap; 202, first annular air gap; 203, radial working air gap; 301, motor housing; 302, motor stator; 303, motor rotor core. Specific embodiments

[0039] Refer to in combination Figures 1 to 8As shown, according to an embodiment of the present invention, a magnetic levitation bearing structure, especially a hybrid magnetic levitation bearing structure, is provided, including: a bearing housing 1, sleeved on a rotating shaft assembly; a radial position adjustment component 2, installed in the bearing housing 1, used to control and adjust the radial displacement of the rotating shaft assembly. Specifically, the radial position adjustment component 2 includes a radial stator core 21 and radial control coils 23 wound around a plurality of stator teeth of the radial stator core 21 (by means of wire embedding); an axial position adjustment component 3, installed in the bearing housing 1, used to control and adjust the axial displacement of the rotating shaft assembly. The axial position adjustment component 3 includes an axial stator core 31 and an axially wound control coil 32 concentric with it; the radial position adjustment component 2 and the axial position adjustment component 3 are axially sleeved on the rotating shaft assembly along the axis of the rotating shaft assembly. An axial working air gap 201 is formed between one side of the axial position adjustment component 3 facing away from the radial position adjustment component 2 and a thrust disc 101 of the rotating shaft assembly; a permanent magnet 4, having an N pole and an S pole, is clamped between the radial position adjustment component 2 and the axial position adjustment component 3, and the N pole faces the side of the axial working air gap 201; it can be understood that the thrust disc 101 is generally assembled integrally with a rotating shaft 102 of the rotating shaft assembly. Of course, in some cases, the thrust disc 101 can also be an integral part of the rotating shaft 102, that is, the thrust disc 101 and the rotating shaft 102 are integrally formed. In either case, at least the material of the thrust disc 101 is a magnetic conductive material (such as 45# magnetic conductive material).

[0040] In this technical solution, by orienting the N pole of the permanent magnet 4 towards the side of the axial working air gap 201, the magnetic force lines emitted by the N pole of the permanent magnet 4 can pass through the axial working air gap 201 along a shorter path, thereby greatly reducing the magnetic leakage phenomenon caused by the path of the magnetic force lines during the passing process, which is beneficial to selecting a smaller volume or a lower grade of permanent magnet to achieve the same axial offset purpose, and further making the structure of the magnetic levitation bearing more compact and reducing the manufacturing cost.

[0041] In addition, in this technical solution, the radial position adjustment component 2 and the axial position adjustment component 3 can control the axial and radial flow directions of the magnetic flux through the coils respectively provided therein, achieving the effect of simultaneous radial-axial control by a single magnetic levitation bearing, with the characteristics of small volume, light weight, high efficiency, etc., and can reduce the axial length of the rotating shaft 102, thereby increasing the critical speed of the motor rotor.

[0042] In some embodiments, a first axial hole of the axial stator core 31 forms a first annular air gap 202 with the rotating shaft assembly. The first annular air gap 202 is not the working air gap for axial or radial position adjustment. A second axial hole of the radial stator core 21 forms a radial working air gap 203 with the rotating shaft assembly. The radial working air gap 203 is the working air gap for adjusting the radial position of the rotating shaft assembly. Together with the axial working air gap 201, it realizes the adjustment of three degrees of freedom of the magnetic suspension bearing, that is, the adjustment control of the axial position and the radial position of the rotating shaft assembly. The radial width of the first annular air gap 202 is smaller than the radial width of the radial working air gap 203. In this technical solution, by designing the radial width of the first annular air gap 202, which is a non-working air gap, to be smaller than the radial width of the radial working air gap 203, which is a radial control working air gap, it can effectively prevent damage to the radial stator core 21 when the rotating shaft assembly deviates from its rotation axis during operation (that is, the circumferential fluctuation of the rotating shaft assembly is large).

[0043] In some embodiments, the radial position control assembly 2 further includes a radial magnetic conduction ring 22. A bearing chamber (not labeled in the figure) is formed on the bearing housing 1. The radial stator core 21 is clamped between the axial bottom wall of the bearing chamber and the radial magnetic conduction ring 22. In the related art, the radial stator core 21 is mostly connected to the bearing housing 1 by an interference fit. The radial stator core 21 is formed by stacking multiple punched sheets. When the radial stator core 21 is assembled into the bearing chamber, it lacks axial press-fitting and positioning, which poses a risk of sheet separation during operation. In the present invention, by clamping the radial magnetic conduction ring 22 (the specific material of which can be, for example, 45# magnetic conduction material) with the axial bottom wall of the bearing chamber, the stacking strength of the radial stator core 21 is improved, effectively preventing the occurrence of sheet separation. In addition, this technical solution can also facilitate the assembly process of the radial stator core 21 in the bearing chamber. Specifically, during the specific assembly of the magnetic suspension bearing, the radial stator core 21 of the present invention can first form an effective connection with the radial magnetic conduction ring 22, and then when the two are assembled as a whole into the bearing, due to the clamping and positioning method of the bearing chamber and the radial magnetic conduction ring 22, there is no need to adopt the relatively cumbersome interference fit method. Preferably, the radial magnetic conduction ring 22 is threadedly connected to the peripheral wall of the bearing chamber.

[0044] In some embodiments, a radial rotor core 103 is sleeved on the outer peripheral wall of the rotating shaft 102 of the rotating shaft assembly corresponding to the radial stator core 21. A radial working air gap 203 is formed between the radial rotor core 103 and the radial stator core 21. The radial rotor core 103 can be sleeved on the rotating shaft 102 in an interference fit manner. Of course, in some cases, the radial rotor core 103 can also be reliably positioned on the rotating shaft 102 by other means.

[0045] In some embodiments, the thrust disc 101 is sleeved on the rotating shaft 102 and can axially position the radial rotor core 103. Further, a magnetic conduction transition collar 104 (the specific material of which can be, for example, 45# magnetic conduction material) is clamped between the thrust disc 101 and the radial rotor core 103. A first annular air gap 202 is formed between the magnetic conduction transition collar 104 and the axial stator core 31. While the thrust disc 101 and the magnetic conduction transition collar 104 form an axial magnetic path conduction medium, they can also effectively fix the radial rotor core 103 axially. Further, the setting of the magnetic conduction transition collar 104 can make the axial width of the axial working air gap 201 between the corresponding axial ends of the thrust disc 101 and the axial stator core 31 within a reasonable range, and can also reduce the sleeved mating surface between the thrust disc 101 and the rotating shaft 102. Especially when the thrust disc 101 and the rotating shaft 102 are in an interference fit, the reduction of the axial length of the sleeved mating surface can significantly reduce the assembly difficulty. The magnetic conduction transition collar 104 and the rotating shaft 102 can be sleeved in an interference or clearance fit manner.

[0046] In some embodiments, the axial position adjustment assembly 3 further includes an axial control coil 32. The axial control coil 32 is disposed on one side of the axial stator core 31 facing the thrust disc 101 through a coil skeleton 33. The coil skeleton 33 serves as a winding carrier for the axial control coil 32, which can facilitate the winding of the axial control coil 32 and can effectively prevent insulation between the axial control coil 32 and the axial stator core 31 when the axial control coil 32 is damaged.

[0047] The coil skeleton 33 has an annular groove 332 and a connecting protrusion 331 that is matched and connected with the groove on the axial stator core 31. The annular groove 332 is used to install the axial control coil 32. The specific structural type of the connecting protrusion 331 can be various, for example, it can be a plurality of convex columns spaced along the circumferential direction, or it can be a continuous annular wall. Its specific setting type should match the groove structural type of the axial end of the axial stator core 31. The axial control coil 32 is bonded to the matching surface of the annular groove 332, for example, by using AB glue to ensure the reliable fixation of the axial control coil 32.

[0048] Any of the radial stator core 21 , the axial stator core 31 , and the radial rotor core 103 may be formed by laminating a plurality of silicon steel sheets.

[0049] The following is combined with Figures 4 to 6 The magnetic force line path and corresponding control of the magnetic bearing structure of the present invention are described as follows:

[0050] like Figure 4 As shown, in order to pass a first direction (in Figure 4 The dotted line is the path of the magnetic field lines when the current flows in the direction shown, from the outside of the paper to the inside), and is specifically the path of the bias magnetic field provided by the magnetic steel 4, which is: magnetic steel 4-axial stator core 31-first annular air gap 202 (or axial working air gap 201-thrust plate 101)-magnetic transition ring 104-radial rotor core 103-radial working air gap 203-radial stator core 21-magnetic steel 4. At this time, it can be seen that the magnetic field lines emitted by the magnetic steel 4 can reach the axial working air gap 201 through the shortest path, thereby improving the magnetic utilization rate; the solid line is the control magnetic field path provided by the axial control coil 32, which is specifically: axial stator core 31-first annular air gap 202-magnetic transition ring 104-thrust plate 101-axial working air gap 201, and the control magnetic field does not pass through the magnetic steel 4. It can be understood that, as Figure 5 As shown, the direction of the current in the axial control coil 32 is exactly opposite to the first direction (the second direction, i.e., from the inside of the paper to the outside). At this time, the bias magnetic circuit direction of the magnet 4 remains unchanged, but the control magnetic circuit direction is exactly opposite.

[0051] The principle of axial control operation is: Figure 4 As shown, the current is energized in the first direction. Due to the difference in direction between the bias magnetic circuit of the magnetic steel 4 and the control magnetic circuit of the axial control coil 32, the magnetic flux density at the axial working air gap 201 is reduced, and the magnetic flux density at the first annular air gap 202 is increased. When the current is appropriate, the magnetic flux density at the axial working air gap 201 is zero, that is, the axial output of the bearing assembly is zero. On the contrary, Figure 5As shown, the current is energized in the second direction. Since there are similarities and differences in the directions of the bias magnetic circuit of the permanent magnet 4 and the control magnetic circuit of the axial control coil 32, the magnetic density at the axial working air gap 201 increases, and the magnetic density at the first annular air gap 202 decreases. When the current is appropriate, the magnetic density at the axial working air gap 201 reaches the maximum, that is, the axial output force of the bearing assembly is the maximum value. It should be noted that according to the aforementioned principle, only the direction of one axis can be controlled. Therefore, a corresponding magnetic suspension bearing should also be required at the other end of the rotating shaft to jointly achieve the axial two-direction control.

[0052] As Figure 6 shown, where the dashed line is the bias magnetic circuit provided by the permanent magnet 4, specifically: permanent magnet 4 - axial stator core 31 - first annular air gap 202 (or axial working air gap 201 - thrust disk 101) - magnetic conduction transition collar 104 - radial rotor core 103 - radial working air gap 203 - radial stator core 21 - permanent magnet 4, that is, it is consistent with the bias magnetic field path provided by the permanent magnet in the axial direction; the solid line is the control magnetic field path provided by the radial control coil 23, specifically: radial rotor core 103 - radial stator core 21 - radial rotor core 103, and the control magnetic field does not pass through the permanent magnet 4.

[0053] The principle of radial control operation is: as Figure 5 shown, the bias magnetic field provided by the permanent magnet 4 is all outward from the circle. When the coil is not energized, the magnetic density in the radial working gap is equal in the circumferential direction (the N pole orientation of the permanent magnet 4 has no obvious influence on the radial bias magnetic density), so the resultant electromagnetic force is zero; the magnitude and direction of the current of the adjustable radial control coil 23 can be adjusted so that the magnetic density at one end of the radial working gap (that is, the radial working air gap 203) increases and the corresponding other end decreases, so that the bearing assembly has a force on the bearing rotor in a certain direction to achieve radial control. It must be mentioned that radial control must be formed at both ends of the rotor (rotating shaft 102) to achieve the radial control of the rotor. Therefore, a bearing assembly (that is, the aforementioned magnetic suspension bearing structure) should also be required at the other end of the rotor (rotating shaft 102) to jointly achieve the radial control effect.

[0054] According to an embodiment of the present invention, there is also provided a motor, including the above-mentioned magnetic levitation bearing structure. The motor has a motor housing 301, and the above-mentioned magnetic levitation bearing structures are respectively provided at both axial ends thereof. A motor rotor core 303 is sleeved in the middle of the rotating shaft 102, and a motor stator 302 is sleeved on the radial outer side of the motor rotor core 303 to form a motor stator-rotor air gap therebetween. The motor stator 302 can be press-fitted into the annular wall of the motor housing 301. Specifically, the magnetic levitation bearing structures are respectively located at both axial ends of the rotating shaft 102, and are respectively fixedly connected in an assembled manner to the corresponding positions at both ends of the motor housing 301 through the assembly positioning holes 11 provided on the corresponding bearing housings 1, so as to realize the support of both ends of the rotating shaft 102 and the motor rotor core 303 on the rotating shaft 102.

[0055] The magnetic levitation bearing structure is assembled in the following manner:

[0056] Assembly of the bearing stator assembly: The radial magnetic conduction ring 22 and the radial stator core 21 are press-fitted by hot sleeve, and then the radial control coil 23 is wound around the corresponding position of the radial stator core 2 to form a radial assembly (i.e., Figure 2 the radial position adjustment assembly shown); the radial assembly, the magnetic steel 4, and the axial stator core 31 after the coil skeleton 33 is assembled are assembled into the bearing housing 1 by hot sleeve, and after cooling, the assembly of the bearing stator assembly is completed.

[0057] Assembly of the bearing rotor assembly: First, the hot sleeve of the radial bearing rotor core 103 (laminated) is sleeved on the rotating shaft 102, then the magnetic conduction transition sleeve ring 104 is sleeved to press the radial bearing rotor core 103, and then the assembly and fixation of the bearing stator assembly are carried out. Specifically, they are respectively fixedly connected in an assembled manner to the corresponding positions at both ends of the motor housing 301 through the assembly positioning holes 11 provided on the corresponding bearing housings 1, and finally the hot sleeve of the thrust disc 101 is carried out.

[0058] It is easy for those skilled in the art to understand that, on the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0059] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention. The above is only the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A magnetic levitation bearing structure, characterized in that, Comprising: A bearing housing (1) sleeved on a rotating shaft assembly; A radial position control assembly (2) installed inside the bearing housing (1) for controlling and adjusting the radial displacement of the rotating shaft assembly; An axial position control assembly (3) installed inside the bearing housing (1) for controlling and adjusting the axial displacement of the rotating shaft assembly. The radial position control assembly (2) and the axial position control assembly (3) are axially sleeved on the rotating shaft assembly. An axial working air gap (201) is formed between one side of the axial position control assembly (3) facing away from the radial position control assembly (2) and a thrust disk (101) of the rotating shaft assembly; A permanent magnet (4) having an N pole and an S pole, clamped between the radial position control assembly (2) and the axial position control assembly (3) with the N pole facing one side of the axial working air gap (201); The axial position control assembly (3) includes an axial stator core (31), and the radial position control assembly (2) includes a radial stator core (21); The rotating shaft assembly further includes a rotating shaft (102). A radial rotor core (103) is sleeved on the outer peripheral wall of the rotating shaft (102) corresponding to the radial stator core (21). A radial working air gap (203) is formed between the radial rotor core (103) and the radial stator core (21). The thrust disk (101) is sleeved on the rotating shaft (102) and can axially position the radial rotor core (103). A magnetic conduction transition collar (104) is further clamped between the thrust disk (101) and the radial rotor core (103). A first annular air gap (202) is formed between the magnetic conduction transition collar (104) and the axial stator core (31). The radial width of the first annular air gap (202) is smaller than the radial width of the radial working air gap (203). The magnetic conduction transition collar (104) is in clearance fit with the rotating shaft (102), and the thrust disk (101) is in interference fit with the rotating shaft (102). A bearing chamber is constructed on the bearing housing (1), and the axial stator core (31) is located at the opening side of the bearing chamber.

2. The magnetic suspension bearing structure according to claim 1, wherein The radial position control assembly (2) further includes a radial magnetic conduction ring (22), and the radial stator core (21) is clamped between the axial bottom wall of the bearing chamber and the radial magnetic conduction ring (22).

3. The magnetic suspension bearing structure according to claim 2, wherein The radial magnetic conduction ring (22) is threadedly connected to the peripheral wall of the bearing chamber.

4. The magnetic suspension bearing structure according to claim 1, wherein The axial position control assembly (3) further includes an axial control coil (32), and the axial control coil (32) is arranged on one side of the axial stator core (31) facing the thrust disk (101) through a coil skeleton (33).

5. The magnetic suspension bearing structure according to claim 4, wherein The coil bobbin (33) has an annular groove (332) and a connecting projection (331) that is cooperatively connected with the groove on the axial stator core (31), and the annular groove (332) is used for mounting the axial control coil (32).

6. A motor, comprising a magnetic suspension bearing structure, characterized in that, The magnetic suspension bearing structure is the magnetic suspension bearing structure according to any one of claims 1 to 5.

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