Magnetic bearing and bearing-less motor

Abstract

A stator of a magnetic bearing according to a first embodiment has a magnetic support unit (4) that is disposed facing in the radial direction of a rotor and that causes a magnetic support force to be generated in the rotor. The magnetic support unit (4) has first teeth (12) and second teeth (13) of a magnetic body, a magnet (7) that causes a bias magnetic flux to be generated in the first teeth (12) and the second teeth (13), and a coil (10) having a conductor part (19) disposed between the first teeth (12) and the second teeth (13). The first teeth (12) and the second teeth (13) have different positions in the axial direction (A1).

Description

Magnetic bearings and bearingless motors

[0001] The present disclosure relates to a magnetic bearing and a bearingless motor, and more particularly to a magnetic bearing and a bearingless motor that support a rotor in a thrust direction.

[0002] Patent Document 1 discloses a magnetic bearing and a rotating machine (bearingless motor) using the same. Generally, a bearingless motor is a rotating electric machine in which a motor winding and a radial support winding are provided on a stator, thereby integrating the motor and magnetic bearing and giving the motor itself a magnetic bearing function.

[0003] The magnetic bearing described in Patent Document 1 is a three-axis magnetic bearing that generates support forces in three axial directions: two radial directions and one thrust direction. Radial support forces are generated by utilizing the imbalance in magnetic flux density obtained by superimposing a bias magnetic flux generated from a permanent magnet and passing through a thrust yoke on the radial magnetic flux of the radial winding. Thrust support forces are generated by utilizing the imbalance in magnetic flux density obtained by superimposing a bias magnetic flux from the permanent magnet on the thrust magnetic flux of the thrust winding.

[0004] JP 2011-85223 A

[0005] In Patent Document 1, a radial control stator is disposed adjacent to the permanent magnet in the thrust direction as a magnetic path for the bias magnetic flux that has passed through the thrust yoke to return to the permanent magnet, which increases the size of the entire magnetic bearing in the thrust direction. Also, a thrust control stator yoke is disposed in the thrust direction of the permanent magnet that generates the bias magnetic flux, which increases the size of the entire magnetic bearing in the thrust direction.

[0006] The present disclosure provides miniaturized magnetic bearings and bearingless motors.

[0007] A magnetic bearing according to one aspect of the present disclosure includes a rotor and a stator. The rotor has a magnetic disk that can rotate in a rotational direction around an axis. The stator has a magnetic support unit that is arranged radially opposite the rotor and generates a magnetic support force on the rotor. The magnetic support unit has first and second teeth that are magnetic, magnets that generate bias magnetic flux in the first and second teeth, and a coil with a conductor portion arranged between the first and second teeth. The first and second teeth are positioned differently in the axial direction.

[0008] A bearingless motor according to one aspect of the present disclosure includes a magnetic bearing and a rotary drive mechanism that rotates a rotor.

[0009] The magnetic bearings and bearingless motors of the present disclosure are miniaturized.

[0010] FIG. 1 is a plan view of a magnetic bearing according to a first embodiment of the present disclosure. FIG. 2 is a schematic perspective view of a magnetic circuit member of a stator of the magnetic bearing according to the first embodiment. FIG. 3 is an enlarged plan view of the magnetic circuit member according to the first embodiment. FIG. 4 is a front view of the magnetic circuit member according to the first embodiment. FIG. 5 is a cross-sectional view of the magnetic circuit member according to the first embodiment (cross-sectional view taken along the V-V arrows in FIG. 3). FIG. 6 is a schematic block diagram showing a control configuration of the magnetic bearing according to the first embodiment. FIG. 7 is an enlarged plan view of the magnetic circuit member according to the first embodiment, showing the flow of magnetic flux when a third magnetic flux is generated. FIG. 8 is a side view of the magnetic circuit member according to the first embodiment, showing the principle of thrust force generation when a third magnetic flux is generated. FIG. 9 is an enlarged plan view of the magnetic circuit member according to the first embodiment, showing the flow of magnetic flux when a fourth magnetic flux is generated. FIG. 10 is a side view of the magnetic circuit member according to the first embodiment, showing the principle of thrust force generation when a fourth magnetic flux is generated. FIG. 11 is a schematic perspective view of a magnetic circuit member of a magnetic bearing according to a second embodiment. FIG. 12 is a front view of the magnetic circuit member according to the first embodiment. FIG. 13 is an enlarged plan view showing the flow of magnetic flux in the magnetic circuit member of the same when fifth magnetic flux, sixth magnetic flux, seventh magnetic flux, and eighth magnetic flux are generated. FIG. 14 is an enlarged plan view showing the flow of magnetic flux in the magnetic circuit member of the same when ninth magnetic flux, tenth magnetic flux, eleventh magnetic flux, and twelfth magnetic flux are generated. FIG. 15 is an enlarged plan view of the magnetic circuit member of the magnetic bearing according to the third embodiment. FIG. 16 is a front view of the magnetic circuit member of the same. FIG. 17 is an enlarged plan view of the magnetic circuit member of the magnetic bearing according to the fourth embodiment. FIG. 18 is a front view of the magnetic circuit member of the same. FIG. 19 is a front view of the magnetic circuit member of the magnetic bearing according to the fifth embodiment. FIG. 20 is a front view of the magnetic circuit member of the magnetic bearing according to the sixth embodiment. FIG. 21 is a front view of the magnetic circuit member of the magnetic bearing according to the seventh embodiment. FIG. 22 is a front view of the magnetic circuit member of the magnetic bearing according to the eighth embodiment. FIG. 23 is a cross-sectional view of a bearingless motor according to the ninth embodiment. Fig. 24 is a plan view of a magnetic bearing of the bearingless motor, Fig. 25 is a plan view of a rotation drive mechanism of the bearingless motor, and Fig. 26 is a schematic block diagram showing a control configuration of the bearingless motor.

[0011] A magnetic bearing and a bearingless motor according to an embodiment of the present disclosure will be described in detail below with reference to the drawings. However, the drawings described in the following embodiments are schematic diagrams, and the ratios of the sizes and thicknesses of the components do not necessarily reflect the actual dimensional ratios. Note that the configurations described in the following embodiments are merely examples of the present disclosure. The present disclosure is not limited to the following embodiments, and various modifications are possible depending on the design, etc., as long as the effects of the present disclosure can be achieved.

[0012] First Embodiment A magnetic bearing 1 according to a first embodiment will be described with reference to FIGS.

[0013] (1) Overall Configuration of Magnetic Bearing Fig. 1 is a plan view of a magnetic bearing 1 according to a first embodiment. The magnetic bearing 1 will be described with reference to Fig. 1.

[0014] The magnetic bearing 1 is a thrust bearing and includes a stator 2 and a rotor 3. The magnetic bearing 1 controls the thrust position of the rotor 3 by creating an imbalance in magnetic flux density. In other words, the magnetic bearing 1 supports the rotor 3 in the thrust direction. The rotor 3 rotates in a rotation direction C1 around an axis R1 along the Z axis of an orthogonal coordinate system having an X axis, a Y axis, and a Z axis. In the following, the direction along the X axis is referred to as the X-axis direction, the direction along the Y axis is referred to as the Y-axis direction, and the direction along the Z axis is referred to as the Z-axis direction. In the following description, the direction in which the axis R1 extends (i.e., the Z-axis direction) is referred to as the axial direction A1.

[0015] (2) Stator Figure 2 is a schematic perspective view of the magnetic circuit member 5 of the stator 2. Figures 3, 4, and 5 are an enlarged plan view, a front view, and a cross-sectional view (cross-sectional view taken along the line V-V in Figure 3) of the magnetic circuit member 5. The stator 2 will be described with reference to Figures 1 to 5.

[0016] The stator 2 is disposed radially opposite the rotor 3 and has a magnetic support unit 4 that supports the rotor 3 in the axial direction A1. That is, the magnetic support unit 4 generates a magnetic support force on the rotor 3. The magnetic support unit 4 is a thrust support stator that has a plurality of (12 in this embodiment) magnetic circuit members 5. The magnetic circuit members 5 are members that generate a thrust force on the rotor 3. The plurality of magnetic circuit members 5 are disposed at equal intervals in the rotational direction C1. The plurality of magnetic circuit members 5 are fixed to, for example, an annular member (not shown).

[0017] Each magnetic circuit member 5 has a thrust core 6, a bias magnet 7, a bias magnetic flux path member 8, and a thrust winding 9. The thrust core 6, the bias magnet 7, and the bias magnetic flux path member 8 are arranged in this order in the rotational direction C1 and connected to each other.

[0018] The thrust core 6 has multiple steel plates stacked in the axial direction A1. The steel plates are magnetic, for example, electromagnetic steel plates such as silicon steel plates. The thrust core 6 has a yoke 11, first teeth 12, and second teeth 13. The yoke 11 has a predetermined length in the rotational direction C1. The first teeth 12 and second teeth 13 extend from the yoke 11 toward the axial center R1, with their tips located close to the outer peripheral surface of the thrust disk 16.

[0019] The first teeth 12 and the second teeth 13 are positioned at different positions in the rotational direction C1. Specifically, the first teeth 12 are positioned close to the bias magnet 7, and the second teeth 13 are positioned farther away from the bias magnet 7. The first teeth 12 are portions that protrude from the yoke 11 toward the axis R1 at a position on the first axial side A11 (upper side in the figure) in the axial direction A1 than the second teeth 13. In this embodiment, the first teeth 12 and the second teeth 13 have the same length in the axial direction A1. It is preferable that the tip surfaces of the first teeth 12 and the second teeth 13 be curved surfaces that correspond to cylindrical surfaces centered on the axis R1 when viewed in the axial direction A1. In this case, the magnetic circuit member 5 can efficiently generate thrust support force.

[0020] The first teeth 12 and the second teeth 13 are located at different positions in the axial direction A1. Specifically, the first teeth 12 are located on a first axial side A11 (upper side in the figure) of the axial direction A1, and the second teeth 13 are located on a second axial side A12 (lower side in the figure) of the axial direction A1. The positions in the axial direction A1 of the lower surfaces of the first teeth 12 and the upper surfaces of the second teeth 13 in the axial direction A1 are aligned. This allows the thrust core 6 to be constructed using laminates of electromagnetic steel sheets of only two types of shapes: one including the first teeth 12 and one including the second teeth 13. This reduces the number of shapes of the electromagnetic steel sheets and improves productivity. Furthermore, if the shape of the electromagnetic steel sheet including the first teeth 12 and the shape of the electromagnetic steel sheet including the second teeth 13 are the same when viewed in the same direction in the axial direction A1, or the same when viewed in a different direction in the axial direction A1, the electromagnetic steel sheet including the first teeth 12 and the electromagnetic steel sheet including the second teeth 13 can be made to have the same shape. This makes it possible to share the same mold for punching the electromagnetic steel sheets, thereby further increasing the productivity of the laminate.

[0021] The thrust winding 9 is a winding for generating a supporting force for supporting the rotor 3 in the axial direction A1. The thrust winding 9 is wound around the second teeth 13 to form thrust coils 10. In the above configuration, the thrust winding 9 has a conductor portion 19 disposed between the first teeth 12 and the second teeth 13.

[0022] The bias magnet 7 generates bias magnetic flux in the first teeth 12 and the second teeth 13. The bias magnet 7 is a permanent magnet. The bias magnet 7 is positioned at a different position relative to the first teeth 12 and the second teeth 13 when viewed from the axial direction A1. That is, the bias magnet 7 does not overlap the first teeth 12 and the second teeth 13 in the axial direction A1. This means that the bias magnet 7 can be formed into a rectangular parallelepiped, improving productivity. Furthermore, since extremely thin portions are eliminated, demagnetization resistance is improved. Furthermore, the side surfaces of the teeth can be made parallel to the axial direction A1, reducing the number of shapes of the electromagnetic steel sheets required. The bias magnet 7 is magnetized in a direction perpendicular to the axial direction A1 (the rotational direction C1 in this embodiment). Specifically, as shown in FIGS. 7 and 9 , the bias magnet 7 generates a first magnetic flux M1 and a second magnetic flux M2 toward the bias magnetic flux path member 8. With the above configuration, the first magnetic flux M1 and the second magnetic flux M2 from the bias magnet 7 flow efficiently through the thrust disk 16, the first teeth 12, and the second teeth 13.

[0023] The bias magnetic flux path member 8 includes a plurality of steel plates stacked in the axial direction A1. The bias magnetic flux path member 8 includes a yoke 14 and bias teeth 15. The bias teeth 15 extend from the yoke 14 toward the axial center R1, with their tips located close to the outer peripheral surface of the thrust disk 16. The bias teeth 15 protrude toward the axial center R1 from the bias magnetic flux path member 8 at the same position in the axial direction A1 as the first teeth 12. It is preferable that the tip surfaces of the bias teeth 15 are curved surfaces that correspond to a cylindrical surface centered on the axial center R1 when viewed in the axial direction A1. In this case, the magnetic circuit member 5 can efficiently generate thrust support force.

[0024] (3) Rotor The rotor 3 will be described with reference to FIG.

[0025] The rotor 3 is attached integrally to a shaft 17, which is the output destination, and transmits torque to the shaft 17. The rotor 3 has a thrust disk 16. The thrust disk 16 is an annular member made of a magnetic material that is rotatable in a rotational direction C1 around an axis R1. The thrust disk 16 faces the stator 2 at a predetermined radial distance. The position of the thrust disk 16 in the axial direction A1 is between the first teeth 12 and the second teeth 13, as shown in FIG. 8 . For example, the center of the thrust disk 16 in the axial direction A1 coincides with the boundary between the first teeth 12 and the second teeth 13 in the axial direction A1.

[0026] (4) Control Configuration of Magnetic Bearing Fig. 6 is a schematic block diagram showing the control configuration of the magnetic bearing 1. The control configuration of the magnetic bearing system will be described with reference to Fig. 6.

[0027] As shown in FIG. 6, the magnetic bearing system includes a magnetic bearing 1, a control device 51, and an inverter 53.

[0028] The magnetic bearing 1 has a thrust disk 16, a thrust winding 9, and a position sensor 52. The position sensor 52 is located at a position radially opposite the thrust disk 16, and detects the thrust position of the rotor 3, for example.

[0029] The control device 51 has, for example, a levitation control unit, a current control unit, and an attitude calculation unit. Each function of the control device 51 is realized, for example, by a computer. The control device 51 has, for example, a processing board made up of a printed circuit board or the like on whose surface an electronic circuit (electrical circuit) is printed. The processing board has, for example, a CPU (Central Processing Unit), memory, etc., and constitutes a computer. The CPU executes a program stored in the memory, causing the computer to function as the control device 51. Note that the control device 51 may also be a hardware circuit designed specifically to realize the above functions.

[0030] The position sensor 52 is a non-contact sensor. The position sensor 52 detects the position of the opposing area of ​​the thrust disk 16 in the axial direction A1. This makes it possible to detect the position of the rotor 3 in the axial direction A1. Furthermore, for example, if a plurality of position sensors 52 are arranged at different positions in the rotational direction C1, it is also possible to detect the attitude of the rotor 3 in the tilt direction (θx, θy) by calculating the signals from each position sensor 52. The type of position sensor 52 can be, but is not limited to, an eddy current sensor.

[0031] The inverter 53 can supply current to the thrust coil 10 .

[0032] (5) Operation of Magnetic Bearing The control device 51 detects the position of the rotor 3 in the axial direction A1 based on the detection signal from the position sensor 52, and causes the inverter 53 to supply current to the thrust coils 10 of the magnetic circuit members 5. As a result, the position of the thrust disk 16 in the axial direction A1 is controlled by the magnetic flux generated from the thrust coils 10 and the magnetic flux generated from the bias magnet 7. In this case, the control device 51 controls the inverter 53 so that the thrust coils 10 of all the magnetic circuit members 5 generate thrust forces on the same side in the axial direction A1 (the first axial side A11 or the second axial side A12).

[0033] (6) Principle of Thrust Force Generation FIG. 7 is an enlarged plan view showing the flow of magnetic flux when the third magnetic flux M3 is generated in the magnetic circuit member 5. FIG. 8 is a side view showing the principle of thrust force generation when the third magnetic flux M3 is generated in the magnetic circuit member 5. FIG. 9 is an enlarged plan view showing the flow of magnetic flux when the fourth magnetic flux M4 is generated in the magnetic circuit member 5. FIG. 10 is a side view showing the principle of thrust force generation when the fourth magnetic flux M4 is generated in the magnetic circuit member 5. Using FIGS. 7 to 10, we will explain the principle of thrust force generation acting on the portion of the thrust disk 16 facing the thrust coil 10 when a positive thrust current and a negative thrust current are applied to one thrust coil 10. Note that the following explanation is premised on the assumption that the first magnetic flux M1 from the bias magnet 7 flows through the bias magnetic flux path member 8, the thrust disk 16, the second teeth 13, and the yoke 11. In addition, the second magnetic flux M2 from the bias magnet 7 flows through the bias magnetic flux passage member 8, the thrust disk 16, and the first teeth 12.

[0034] (6-1) First Operating State In FIG. 7, a positive thrust current is applied to the thrust coil 10, causing the thrust coil 10 to generate a third magnetic flux M3. The third magnetic flux M3 flows from the second teeth 13 to the thrust disk 16 and the first teeth 12. As a result, in the first region L1 between the first teeth 12 and the thrust disk 16, the second magnetic flux M2 and the third magnetic flux M3 are oriented in the same direction, resulting in a high magnetic flux density in the first region L1. Meanwhile, in the second region L2 between the second teeth 13 and the thrust disk 16, the first magnetic flux M1 and the third magnetic flux M3 are oriented in opposite directions and cancel each other out, resulting in a low magnetic flux density in the second region L2. As a result, as shown in FIG. 8, a thrust force F1 acts on the portion of the thrust disk 16 facing the magnetic circuit member 5 toward the first axial side A11.

[0035] (6-2) Second Operating State In FIG. 9 , a negative thrust current is applied to the thrust coil 10, causing the thrust coil 10 to generate a fourth magnetic flux M4. The fourth magnetic flux M4 flows in the opposite direction to the third magnetic flux M3 and flows from the first teeth 12 to the thrust disk 16 and the second teeth 13. As a result, in the first region L1 between the second teeth 13 and the thrust disk 16, the first magnetic flux M1 and the fourth magnetic flux M4 are oriented in the same direction, resulting in a high magnetic flux density in the first region L1. Meanwhile, in the second region L2 between the first teeth 12 and the thrust disk 16, the second magnetic flux M2 and the fourth magnetic flux M4 are oriented in the opposite direction, resulting in a low magnetic flux density in the second region L2. As a result, as shown in FIG. 10 , a thrust force F2 acts on the portion of the thrust disk 16 facing the magnetic circuit member 5 toward the second axial side A12.

[0036] (7) Effects According to this embodiment, thrust force can be generated with a simple structure, so the magnetic bearing 1 can be made smaller.

[0037] Second Embodiment In the first embodiment, the magnetic circuit member 5 has one first tooth 12 and one second tooth 13. However, the number of first teeth and second teeth is not particularly limited. Below, an example in which the number of first teeth and second teeth is different will be described.

[0038] A magnetic circuit member 5A according to the second embodiment will be described with reference to Figures 11 to 14. The magnetic bearing of the second embodiment has the same basic configuration and basic operation as the magnetic bearing 1 of the first embodiment, so the following description will focus on the differences.

[0039] 11 and 12 are schematic perspective and front views of a magnetic circuit member 5A of a magnetic bearing according to the second embodiment. As shown in Fig. 11 and 12, the magnetic circuit member 5A has a thrust core 6A, a bias magnet 7A, and a thrust winding 9A. The thrust core 6A and the bias magnet 7A are arranged in this order in the rotational direction C1 and are connected to each other.

[0040] The thrust core 6A has multiple steel plates stacked in the axial direction A1. The thrust core 6A has a yoke 11A, a pair of first teeth 12A, and a pair of second teeth 13A. The yoke 11A has a predetermined length in the rotational direction C1. The pair of first teeth 12A and second teeth 13A extend from the yoke 11A toward the axis R1, with their tips adjacent to the outer peripheral surface of the thrust disk 16A.

[0041] The pair of first teeth 12A and second teeth 13A are positioned at different positions in the rotational direction C1. Specifically, one of the first teeth 12A is located close to the bias magnet 7A, while the other first tooth 12A is located farther away from the bias magnet 7A. The second teeth 13A are located between the pair of first teeth 12A in the rotational direction C1. In this embodiment, the second teeth 13A are longer than the first teeth 12A in the rotational direction C1.

[0042] The pair of first teeth 12A and second teeth 13A are positioned at different positions in the axial direction A1. Specifically, the pair of first teeth 12A are arranged on a first axial side A11 (upper side in the figure) in the axial direction A1, and the pair of second teeth 13A are arranged on a second axial side A12 (lower side in the figure) in the axial direction A1.

[0043] The thrust winding 9A is a winding for generating a supporting force for supporting a rotor (not shown) in the axial direction A1. The thrust winding 9A is wound around the second teeth 13A to form thrust coils 10A. In the above configuration, the thrust winding 9A has a pair of conductor portions 19A arranged between the first teeth 12A and the second teeth 13A.

[0044] The bias magnet 7A generates bias magnetic flux in the first teeth 12A and the second teeth 13A. The bias magnet 7A is a permanent magnet. The bias magnet 7A is positioned at different positions relative to the pair of first teeth 12A and second teeth 13A when viewed from the axial direction A1. In other words, the bias magnet 7A does not overlap the first teeth 12A and the second teeth 13A in the axial direction A1. This means that the bias magnet 7A can be formed into a rectangular parallelepiped, improving productivity. Furthermore, the elimination of extremely thin-walled portions improves demagnetization resistance. Furthermore, the side surfaces of the teeth can be made parallel to the axial direction A1, reducing the number of shapes of the electromagnetic steel sheets required. The bias magnet 7A is magnetized in the rotational direction C1. Specifically, the bias magnet 7A generates bias magnetic flux in the direction opposite to the thrust core 6A in the rotational direction C1. With the above configuration, the bias magnetic flux from the bias magnet 7A flows efficiently through the thrust disk 16A, the first teeth 12A, and the second teeth 13A.

[0045] Fig. 13 is an enlarged plan view showing the flow of magnetic flux in the magnetic circuit member 5A when a fifth magnetic flux M15, a sixth magnetic flux M16, a seventh magnetic flux M17, and an eighth magnetic flux M18 are generated. Fig. 14 is an enlarged plan view showing the flow of magnetic flux in the magnetic circuit member 5A when a ninth magnetic flux M19, a tenth magnetic flux M20, an eleventh magnetic flux M21, and a twelfth magnetic flux M22 are generated. Figs. 13 and 14 show a structure in which a pair of magnetic circuit members 5A are connected. Specifically, another magnetic circuit member 5A is connected to one side (the left side in the figure) of the magnetic circuit member 5A in the rotational direction C1 with a bias magnet 7A between them.

[0046] 13 and 14 , the principle of thrust force generation acting on the portion of the thrust disk 16A facing the thrust coil 10A when a positive thrust current and a negative thrust current are applied to the two thrust coils 10A will be described. Note that, as a premise for the following description, the first magnetic flux M11 from the bias magnet 7A flows through the yoke 11A of the magnetic circuit member 5A on the left side of the figure, the first tooth 12A on the left side of the magnetic circuit member 5A on the left side of the figure, the thrust disk 16A, and the first tooth 12A and yoke 11A on the right side of the magnetic circuit member 5A on the right side of the figure. Furthermore, the second magnetic flux M12 and the third magnetic flux M13 from the bias magnet 7A flow through the second tooth 13A of the magnetic circuit member 5A on the left side of the figure, the thrust disk 16A, and the second tooth 13A of the magnetic circuit member 5A on the right side of the figure. Furthermore, a fourth magnetic flux M14 from the bias magnet 7A flows through the first tooth 12A on the right side of the magnetic circuit member 5A on the left side of the figure, the thrust disk 16A, and the first tooth 12A on the left side of the magnetic circuit member 5A on the right side of the figure.

[0047] (2-1) First Operating State In Figure 13, a positive thrust current is applied to the thrust coil 10A of the magnetic circuit member 5A on the right side of the figure, causing the thrust coil 10A to generate a fifth magnetic flux M15 and a sixth magnetic flux M16. The fifth magnetic flux M15 flows from the second tooth 13A to the thrust disk 16A and to the first tooth 12A on the right side of the figure. The sixth magnetic flux M16 flows from the second tooth 13A to the thrust disk 16A and to the first tooth 12A on the left side of the figure. As a result, in the first region L1 between the first tooth 12A and the thrust disk 16A on the right side of the figure and the left side of the figure, the first magnetic flux M11 and the fifth magnetic flux M15, and the fourth magnetic flux M14 and the sixth magnetic flux M16, respectively, are oriented in the same direction, thereby increasing the magnetic flux density in the first region L1. On the other hand, in the second region L2 between the second tooth 13A and the thrust disk 16A, the second magnetic flux M12 and the third magnetic flux M13 and the fifth magnetic flux M15 and the sixth magnetic flux M16 have opposite directions, so the magnetic flux density is low.

[0048] In FIG. 13 , a negative thrust current is applied to the thrust coil 10A of the magnetic circuit member 5A on the left side of the figure, causing the thrust coil 10A to generate a seventh magnetic flux M17 and an eighth magnetic flux M18. The seventh magnetic flux M17 flows from the first tooth 12A on the right side to the thrust disk 16A and the second tooth 13A. The eighth magnetic flux M18 flows from the first tooth 12A on the left side to the thrust disk 16A and the second tooth 13A. As a result, in the first region L1 between the first tooth 12A and the thrust disk 16A on the right side of the figure, the fourth magnetic flux M14 and the seventh magnetic flux M17 have the same orientation, resulting in a high magnetic flux density. Furthermore, in the first region L1 between the first tooth 12A and the thrust disk 16A on the left side of the figure, the first magnetic flux M11 and the eighth magnetic flux M18 have the same orientation, resulting in a high magnetic flux density. On the other hand, in the second region L2 between the second tooth 13A and the thrust disk 16A, the direction of the second magnetic flux M12 and the third magnetic flux M13 is opposite to the direction of the seventh magnetic flux M17 and the eighth magnetic flux M18, so the magnetic flux density is low.

[0049] As a result, a thrust force acts on the portion of the thrust disk 16A facing the magnetic circuit member 5A toward the first axial side A11.

[0050] (2-2) Second Operating State In Figure 14, a negative thrust current is applied to the thrust coil 10A of the magnetic circuit member 5A on the right side of the figure, causing the thrust coil 10A to generate a ninth magnetic flux M19 and a tenth magnetic flux M20. The ninth magnetic flux M19 flows from the first tooth 12A on the right side of the figure to the thrust disk 16A and the second tooth 13. The tenth magnetic flux M20 flows from the first tooth 12A on the left side of the figure to the thrust disk 16A and the second tooth 13A. As a result, the second magnetic flux M12 and the third magnetic flux M13 and the ninth magnetic flux M19 and the tenth magnetic flux M20 are oriented in the same direction between the second tooth 13A and the thrust disk 16A, creating a first region L1 with high magnetic flux density. Furthermore, between the first tooth 12A and thrust disk 16A on the right side of the figure, the first magnetic flux M11 and the ninth magnetic flux M19 have opposite directions, creating a second region L2 with low magnetic flux density.Furthermore, between the first tooth 12A and thrust disk 16A on the left side of the figure, the fourth magnetic flux M14 and the tenth magnetic flux M20 have opposite directions, creating a second region L2 with low magnetic flux density.

[0051] 14 , a positive thrust current is applied to the thrust coil 10A of the magnetic circuit member 5A on the left side of the figure, causing the thrust coil 10A to generate an eleventh magnetic flux M21 and a twelfth magnetic flux M22. The eleventh magnetic flux M21 flows from the second tooth 13A to the thrust disk 16A and to the first tooth 12A on the right side of the figure. The twelfth magnetic flux M22 flows from the second tooth 13A to the thrust disk 16A and to the first tooth 12A on the left side of the figure. As a result, the second magnetic flux M12 and the third magnetic flux M13 and the eleventh magnetic flux M21 and the twelfth magnetic flux M22 are oriented in the same direction between the second tooth 13A and the thrust disk 16A, creating a first region L1 with high magnetic flux density. Furthermore, between the first tooth 12A and the thrust disk 16A on the right side of the figure, the fourth magnetic flux M14 and the eleventh magnetic flux M21 have opposite directions, creating a second region L2 with low magnetic flux density.Furthermore, between the second tooth 13A and the thrust disk 16A on the left side of the figure, the first magnetic flux M11 and the twelfth magnetic flux M22 have opposite directions, creating a second region L2 with low magnetic flux density.

[0052] The first region L1 generates a force that pulls the thrust disk 16A toward the second teeth 13A. As a result, a thrust force toward the second axial side A12 acts on the portion of the thrust disk 16A that faces the magnetic circuit member 5A.

[0053] In the second embodiment, the same effects as in the first embodiment can be obtained.

[0054] Furthermore, in the second embodiment, by providing one magnetic circuit member 5A with three teeth, the thrust coil 10A can be used effectively, and as a result, the thrust supporting force can be increased.

[0055] (Third Embodiment) In the magnetic circuit member 5 according to the first embodiment, the thrust winding 9 is wound around the second tooth 13. However, the position at which the thrust winding is wound is not particularly limited as long as the thrust winding (coil) has a conductor portion between the first tooth and the second tooth. Below, an example in which the thrust winding is wound at a different position will be described.

[0056] 15 and 16 are enlarged plan and front views of a magnetic circuit member 5B of a magnetic bearing according to the third embodiment. The magnetic circuit member 5B according to the third embodiment will be described using Figures 15 to 16. Note that the magnetic bearing according to the third embodiment has the same basic configuration and basic operation as the magnetic bearing 1 according to the first embodiment, so the following description will focus on the differences.

[0057] The magnetic circuit member 5B has a thrust core 6B, a bias magnet 7B, a bias magnetic flux path member 8B, and a thrust winding 9B. The thrust core 6B, bias magnet 7B, and bias magnetic flux path member 8B are arranged in this order in the rotational direction C1 and connected to one another.

[0058] The thrust core 6B has multiple steel plates stacked in the axial direction A1. The thrust core 6B has a yoke 11B, first teeth 12B, and second teeth 13B. The yoke 11B has a predetermined length in the rotational direction C1. The yoke 11B is shorter in the axial direction A1 than in the first embodiment. The first teeth 12B and second teeth 13B extend from the yoke 11B toward the axis R1, with their tips close to the outer peripheral surface of a thrust disk (not shown).

[0059] The first teeth 12B and the second teeth 13B are located at different positions in the rotational direction C1. Specifically, the first teeth 12B are located close to the bias magnet 7B, and the second teeth 13B are located farther away from the bias magnet 7B. The first teeth 12B protrude from the yoke 11B toward the axis R1 at a position on the first axial side A11 (upper side in the figure) in the axial direction A1 than the second teeth 13B. In this embodiment, the first teeth 12B and the second teeth 13B have the same length in the axial direction A1.

[0060] The first teeth 12B and the second teeth 13B are positioned at different positions in the axial direction A1. Specifically, the first teeth 12B are positioned on a first axial side A11 (upper side in the figure) in the axial direction A1, and the second teeth 13B are positioned on a second axial side A12 (lower side in the figure) in the axial direction A1.

[0061] The thrust winding 9B is a winding for generating a supporting force that supports the rotor (not shown) in the axial direction A1. The thrust winding 9B is wound around a yoke 11B to form a thrust coil 10B. In the above-described toroidal winding configuration, the thrust winding 9B has a conductor portion 19B disposed between the first tooth 12B and the second tooth 13B.

[0062] The bias magnet 7B generates bias magnetic flux in the first teeth 12B and the second teeth 13B. The bias magnet 7B is a permanent magnet. The bias magnet 7B is positioned at different positions relative to the first teeth 12B and the second teeth 13B when viewed from the axial direction A1. In other words, the bias magnet 7B does not overlap the first teeth 12B and the second teeth 13B in the axial direction A1. As a result, the bias magnet 7B can be formed into a rectangular parallelepiped, improving productivity. Furthermore, since extremely thin portions are eliminated, demagnetization resistance is improved. Furthermore, the side surfaces of the teeth can be made parallel to the axial direction A1, reducing the number of shapes of the electromagnetic steel sheets required. The bias magnet 7B is magnetized in the rotational direction C1. Specifically, the bias magnet 7B generates magnetic flux toward the thrust core 6B. With the above configuration, magnetic flux from the bias magnet 7B flows efficiently through the thrust disk, the first teeth 12B, and the second teeth 13B.

[0063] The bias magnetic flux path member 8B has multiple steel plates stacked in the axial direction A1. The bias magnetic flux path member 8B has a yoke 14B and bias teeth 15B. The bias teeth 15B extend from the yoke 14B toward the axial direction R1, with their tips close to the outer peripheral surface of the thrust disk. The bias teeth 15B protrude from the bias magnetic flux path member 8B toward the axial direction R1 at the same position as the first teeth 12B in the axial direction A1.

[0064] In the third embodiment, the same effects as in the first embodiment can be obtained.

[0065] Furthermore, in the third embodiment, the length of the magnetic circuit member 5B in the rotation direction C1 can be made shorter than in the first embodiment.

[0066] (Fourth Embodiment) In the magnetic circuit member 5 according to the first embodiment, the thrust winding 9 is wound around one second tooth 13. However, the number of teeth around which one thrust winding is wound is not particularly limited, as long as the thrust winding (coil) has a conductor portion between the first tooth and the second tooth. Below, an example in which a common thrust winding is wound around multiple teeth will be described.

[0067] 17 and 18 are enlarged plan and front views of a magnetic circuit member 5C of a magnetic bearing according to the fourth embodiment. The magnetic circuit member 5C according to the fourth embodiment will be described using Figures 17 to 18. Note that the magnetic bearing according to the fourth embodiment has the same basic configuration and basic operation as the magnetic bearing 1 according to the first embodiment, so the following description will focus on the differences.

[0068] The magnetic circuit member 5C includes a pair of thrust cores 6C, a bias magnet 7C, and a thrust winding 9C. The thrust cores 6C, bias magnet 7C, and thrust core 6C are arranged in this order in the rotational direction C1 and connected to one another.

[0069] Each thrust core 6C has multiple steel plates stacked in the axial direction A1. Each thrust core 6C has a yoke 11C, first teeth 12C, and second teeth 13C. The yoke 11C has a predetermined length in the rotational direction C1. The first teeth 12C and second teeth 13C extend from the yoke 11C toward the axis R1, with their tips adjacent to the outer circumferential surface of a thrust disk (not shown).

[0070] In each thrust core 6C, the first teeth 12C and the second teeth 13C are located at different positions in the rotational direction C1. Specifically, the second teeth 13C are located close to the bias magnet 7C, and the first teeth 12C are located farther away from the bias magnet 7C. The first teeth 12C protrude from the yoke 11C toward the axis R1 at a position on the first axial side A11 (upper side in the figure) in the axial direction A1 than the second teeth 13C. In this embodiment, the first teeth 12C and the second teeth 13C have the same length in the axial direction A1.

[0071] The first teeth 12C and the second teeth 13C are positioned at different positions in the axial direction A1. Specifically, the first teeth 12C are positioned on a first axial side A11 (upper side in the figure) in the axial direction A1, and the second teeth 13C are positioned on a second axial side A12 (lower side in the figure) in the axial direction A1.

[0072] The thrust winding 9C is a winding for generating a supporting force that supports the rotor (not shown) in the axial direction A1. The thrust winding 9C is wound around a yoke 11C to form a thrust coil 10C. In the above configuration, the thrust winding 9C has a conductor portion 19C disposed between the first tooth 12C and the second tooth 13C.

[0073] The bias magnet 7C generates bias magnetic flux in the first teeth 12C and the second teeth 13C. The bias magnet 7C is a permanent magnet. The bias magnet 7C is arranged between the yoke 11C of one thrust core 6C and the yoke 11C of the other thrust core 6C in the rotational direction C1. The bias magnet 7C is magnetized in the rotational direction C1. Specifically, the bias magnet 7C generates magnetic flux toward one thrust core 6C. With the above configuration, the magnetic flux from the bias magnet 7C flows efficiently through the thrust disk and the first teeth 12C and second teeth 13C of the pair of thrust cores 6C.

[0074] In the fourth embodiment, the same effects as in the first embodiment can be obtained.

[0075] Furthermore, in the fourth embodiment, one magnetic circuit member 5C has four teeth, and one thrust winding 9C is wound around two second teeth 13C, thereby making effective use of the coil, and as a result, the thrust supporting force of the magnetic circuit member 5 can be increased.

[0076] Fifth Embodiment In the magnetic circuit member 5 according to the first embodiment, the number of bias magnets 7 is one. However, the number of magnets is not particularly limited. An example in which a plurality of magnets are provided will be described below.

[0077] Fig. 19 is a front view of a magnetic circuit member 5D of a magnetic bearing according to the fifth embodiment. The magnetic circuit member 5D according to the fifth embodiment will be described using Fig. 19. Note that the magnetic bearing according to the fifth embodiment has the same basic configuration and basic operation as the magnetic bearing 1 according to the first embodiment, and therefore the following description will focus on the differences.

[0078] The magnetic circuit member 5D has a thrust core 6D, a pair of bias magnets 7D, a pair of bias magnetic flux path members 8D, and a thrust winding 9D. The bias magnets 7D and the bias magnetic flux path members 8D are arranged in this order on both sides of the thrust core 6D in the rotation direction C1 and are connected to each other.

[0079] The thrust core 6D has multiple steel plates stacked in the axial direction A1. The thrust core 6D has a yoke 11D, a pair of first teeth 12D, and a pair of second teeth 13D. The yoke 11D has a predetermined length in the rotational direction C1. The pair of first teeth 12D and second teeth 13D extend from the yoke 11D toward the axis R1, with their tips adjacent to the outer peripheral surface of a thrust disk (not shown).

[0080] The pair of first teeth 12D and second teeth 13D are positioned at different positions in the rotational direction C1. Specifically, one first tooth 12D is located close to one bias magnet 7D, and the other first tooth 12D is located close to the other bias magnet 7D. The second teeth 13D are located between the pair of first teeth 12D in the rotational direction C1. In this embodiment, the second teeth 13D are longer in the rotational direction C1 than the first teeth 12D.

[0081] The pair of first teeth 12D and second teeth 13D are positioned at different positions in the axial direction A1. Specifically, the pair of first teeth 12D are arranged on a first axial side A11 (upper side in the figure) in the axial direction A1, and the pair of second teeth 13D are arranged on a second axial side A12 (lower side in the figure) in the axial direction A1.

[0082] The thrust winding 9D is a winding for generating a supporting force for supporting a rotor (not shown) in the axial direction A1. The thrust winding 9D is wound around the second teeth 13D to form thrust coils 10D. In the above configuration, the thrust winding 9D has a pair of conductor portions 19D arranged between the pair of first teeth 12D and second teeth 13D.

[0083] The pair of bias magnets 7D generate bias magnetic flux in the pair of first teeth 12D and second teeth 13D. The bias magnets 7D are permanent magnets. The pair of bias magnets 7D are arranged at different positions relative to the pair of first teeth 12D and second teeth 13D when viewed in the axial direction A1. In other words, the pair of bias magnets 7D do not overlap with the pair of first teeth 12D and second teeth 13D in the axial direction A1. The pair of bias magnets 7D are magnetized in the rotational direction C1. Specifically, one bias magnet 7D generates bias magnetic flux toward one bias magnetic flux path member 8D. The other bias magnet 7D generates bias magnetic flux toward the other bias magnetic flux path member 8D. With the above configuration, magnetic flux from the pair of bias magnets 7D flows efficiently through the thrust disk, the pair of first teeth 12D, and the second teeth 13D.

[0084] The pair of bias magnetic flux path members 8D includes multiple steel plates stacked in the axial direction A1. Each bias magnetic flux path member 8D includes a yoke 14D and bias teeth 15D. The bias teeth 15D extend from the yoke 14D toward the axial direction R1, with their tips close to the outer peripheral surface of the thrust disk. The bias teeth 15D protrude from the bias magnetic flux path member 8D toward the axial direction R1 at the same position as the first teeth 12D in the axial direction A1.

[0085] In the fifth embodiment, the same effects as in the first embodiment can be obtained.

[0086] Sixth Embodiment In the first embodiment, the magnetic circuit member 5 is configured from a single magnetic circuit member. However, a plurality of magnetic circuit members may be connected together. An example in which a plurality of magnetic circuit members are connected together will be described below.

[0087] Fig. 20 is a front view of a magnetic circuit member 5E of a magnetic bearing according to the sixth embodiment. The magnetic circuit member 5E according to the sixth embodiment will be described using Fig. 20. Note that the magnetic bearing according to the sixth embodiment has the same basic configuration and basic operation as the magnetic bearing 1 according to the first embodiment, and therefore the following description will focus on the differences.

[0088] 20 shows a structure in which a pair of magnetic circuit members are connected as a magnetic circuit member 5E. A bias magnet 71E is disposed between the pair of magnetic circuit members in the rotational direction C1.

[0089] Each magnetic circuit member includes a thrust core 6E, a bias magnet 7E, a bias magnetic flux path member 8E, and a thrust winding 9E. In each magnetic circuit member, the bias magnet 7E and the bias magnetic flux path member 8E are arranged in this order and connected to each other on one side of the thrust core 6E in the rotation direction C1 (the side away from the bias magnet 71E).

[0090] The thrust core 6E has multiple steel plates stacked in the axial direction A1. The thrust core 6E has a yoke 11E, a pair of first teeth 12E, and a pair of second teeth 13E. The yoke 11E has a predetermined length in the rotational direction C1. The pair of first teeth 12E and second teeth 13E extend from the yoke 11E toward the axial center R1, with their tips adjacent to the outer peripheral surface of a thrust disk (not shown).

[0091] The pair of first teeth 12E and second teeth 13E are positioned at different positions in the rotational direction C1. Specifically, one of the first teeth 12E is located close to the bias magnet 7E, while the other first tooth 12E is located farther away from the bias magnet 7E. The second teeth 13E are located between the pair of first teeth 12E in the rotational direction C1. In this embodiment, the second teeth 13E are longer than the first teeth 12E in the rotational direction C1.

[0092] The pair of first teeth 12E and second teeth 13E are positioned at different positions in the axial direction A1. Specifically, the pair of first teeth 12E are arranged on a first axial side A11 (upper side in the figure) in the axial direction A1, and the pair of second teeth 13E are arranged on a second axial side A12 (lower side in the figure) in the axial direction A1.

[0093] The thrust winding 9E is a winding for generating a supporting force for supporting a rotor (not shown) in the axial direction A1. The thrust winding 9E is wound around the second teeth 13E to form thrust coils 10E. In the above configuration, the thrust winding 9E has a pair of conductor portions 19E disposed between the pair of first teeth 12E and second teeth 13E.

[0094] In each magnetic circuit member, the bias magnet 7E generates a bias magnetic flux in the pair of first teeth 12E and second teeth 13E. The bias magnet 7E is a permanent magnet. The bias magnet 7E is disposed at a different position relative to the pair of first teeth 12E and second teeth 13E when viewed in the axial direction A1. In other words, the bias magnet 7E does not overlap the pair of first teeth 12E and second teeth 13E in the axial direction A1. The bias magnet 7E is magnetized in the rotational direction C1. Specifically, one bias magnet 7E in one magnetic circuit member generates a bias magnetic flux toward one bias magnetic flux path member 8E. The other bias magnet 7E in the other magnetic circuit member generates a bias magnetic flux toward the other bias magnetic flux path member 8E. Furthermore, the bias magnet 71E is magnetized in the rotational direction C1. Specifically, the bias magnet 71E generates a bias magnetic flux toward one magnetic circuit member. With the above configuration, in each magnetic circuit member, the magnetic flux from the bias magnet 7E flows efficiently through the thrust disk, the pair of first teeth 12E, and the second teeth 13E.

[0095] The bias magnetic flux path member 8E has multiple steel plates stacked in the axial direction A1. The bias magnetic flux path member 8E has a yoke 14E and bias teeth 15E. The bias teeth 15E extend from the yoke 14E toward the axial direction R1, with their tips close to the outer peripheral surface of the thrust disk. The bias teeth 15E protrude from the bias magnetic flux path member 8E toward the axial direction R1 at the same position as the first teeth 12E in the axial direction A1.

[0096] In the sixth embodiment, the same effects as in the first embodiment can be obtained.

[0097] Furthermore, in the sixth embodiment, by connecting a pair of magnetic circuit members, the magnetic circuit member 5E is realized as being long in the rotational direction C1. In other words, the magnetic circuit members can be installed without any gaps in the rotational direction C1. As a result, the thrust supporting force of the magnetic circuit member 5E can be increased.

[0098] Seventh Embodiment In the magnetic circuit member 5 according to the first embodiment, the second teeth 13 wound with the thrust winding 9 are disposed on the second axial side A12 in the axial direction A1, and the first teeth 12 are disposed on the first axial side A11 in the axial direction A1. However, the positions of the first teeth and second teeth in the axial direction A1 may be reversed. Such an example will be described below.

[0099] Fig. 21 is a front view of a magnetic circuit member 5G of a magnetic bearing according to the seventh embodiment. The magnetic circuit member 5G according to the seventh embodiment will be described using Fig. 21. Note that the magnetic bearing according to the seventh embodiment has the same basic configuration and basic operation as the magnetic bearing 1 according to the first embodiment, and therefore the following description will focus on the differences.

[0100] The magnetic circuit member 5G includes a thrust core 6G, a bias magnet 7G, a bias magnetic flux path member 8G, and a thrust winding 9G. The thrust core 6G, bias magnet 7G, and bias magnetic flux path member 8G are arranged in this order in the rotational direction C1 and connected to one another.

[0101] The thrust core 6G has multiple steel plates stacked in the axial direction A1. The thrust core 6G has a yoke 11G, first teeth 12G, and second teeth 13G. The yoke 11G has a predetermined length in the rotational direction C1. The first teeth 12G and second teeth 13G extend from the yoke 11G toward the axis R1, with their tips adjacent to the outer peripheral surface of a thrust disk (not shown).

[0102] The first teeth 12G and the second teeth 13G are positioned differently in the rotation direction C1. Specifically, the first teeth 12G are positioned close to the bias magnet 7G, and the second teeth 13G are positioned farther away from the bias magnet 7G.

[0103] The first teeth 12G and the second teeth 13G are positioned at different positions in the axial direction A1. Specifically, the first teeth 12G are positioned on the second axial side A12 (lower side in the figure) of the axial direction A1, and the second teeth 13G are positioned on the first axial side A11 (upper side in the figure) of the axial direction A1.

[0104] The thrust winding 9G is a winding for generating a supporting force that supports the rotor (not shown) in the axial direction A1. The thrust winding 9G is wound around the second teeth 13G to form thrust coils 10G. In the above configuration, the thrust winding 9G has a conductor portion 19G disposed between the first teeth 12G and the second teeth 13G.

[0105] The bias magnet 7G generates bias magnetic flux in the first teeth 12G and the second teeth 13G. The bias magnet 7G is a permanent magnet. The bias magnet 7G is disposed at a different position relative to the first teeth 12G and the second teeth 13G when viewed in the axial direction A1. In other words, the bias magnet 7G does not overlap with the first teeth 12G and the second teeth 13G in the axial direction A1. The bias magnet 7G is magnetized in the rotational direction C1. Specifically, the bias magnet 7G generates bias magnetic flux toward the bias magnetic flux path member 8G. With the above configuration, the magnetic flux from the bias magnet 7G flows efficiently through the thrust disk, first teeth 12G, and second teeth 13G.

[0106] The bias magnetic flux path member 8G has multiple steel plates stacked in the axial direction A1. The bias magnetic flux path member 8G has a yoke 14B and bias teeth 15G. The bias teeth 15G extend from the yoke 14G toward the axial direction R1, with their tips close to the outer peripheral surface of the thrust disk. The bias teeth 15G protrude from the bias magnetic flux path member 8G toward the axial direction R1 at the same position as the second teeth 13G in the axial direction A1.

[0107] In the seventh embodiment, the same effects as in the first embodiment can be obtained.

[0108] Eighth Embodiment In the magnetic circuit member 5 according to the first embodiment, the bias magnet 7 is a rectangular parallelepiped, and when viewed in the axial direction A1, the bias magnet 7 does not overlap the first teeth 12 and the second teeth 13 in the axial direction A1. However, the magnet may have a different shape. Such examples will be described below.

[0109] Fig. 22 is a front view of a magnetic circuit member 5H of a magnetic bearing according to the eighth embodiment. The magnetic circuit member 5H according to the eighth embodiment will be described using Fig. 22. Note that the magnetic bearing according to the eighth embodiment has the same basic configuration and basic operation as the magnetic bearing 1 according to the first embodiment, and therefore the following description will focus on the differences.

[0110] The magnetic circuit member 5H has a thrust core 6H, a bias magnet 7H, a bias magnetic flux path member 8H, and a thrust winding 9H. The thrust core 6H, bias magnet 7H, and bias magnetic flux path member 8H are arranged in this order in the rotational direction C1 and connected to one another.

[0111] The thrust core 6H has multiple steel plates stacked in the axial direction A1. The thrust core 6H has a yoke 11H, first teeth 12H, and second teeth 13H. The yoke 11H has a predetermined length in the rotational direction C1. The first teeth 12H and second teeth 13H extend from the yoke 11H toward the axis R1, with their tips adjacent to the outer peripheral surface of a thrust disk (not shown).

[0112] The first teeth 12H and the second teeth 13H are located at different positions in the rotational direction C1. Specifically, the first teeth 12H are located close to the bias magnet 7H, and the second teeth 13H are located farther away from the bias magnet 7H. The first teeth 12H are portions that protrude from the yoke 11H toward the axis R1 at a position on the first axial side A11 (upper side in the figure) in the axial direction A1 than the second teeth 13H. In this embodiment, the first teeth 12H and the second teeth 13H have the same length in the axial direction A1.

[0113] The first teeth 12H and the second teeth 13H are positioned at different positions in the axial direction A1. Specifically, the first teeth 12H are positioned on a first axial side A11 (upper side in the figure) in the axial direction A1, and the second teeth 13H are positioned on a second axial side A12 (lower side in the figure) in the axial direction A1.

[0114] The thrust winding 9H is a winding for generating a supporting force for supporting the rotor (not shown) in the axial direction A1. The thrust winding 9H is wound around the second teeth 13H to form thrust coils 10H. In the above configuration, the thrust winding 9H has a conductor portion 19H arranged between the first teeth 12H and the second teeth 13H.

[0115] The bias magnet 7H generates bias magnetic flux in the first teeth 12H and the second teeth 13H. The bias magnet 7H is a permanent magnet. The bias magnet 7H has a portion that overlaps with the first teeth 12H when viewed from the axial direction A1. Specifically, as shown in FIG. 22 , the bias magnet 7H has a slope that approaches the first teeth 12H as it moves toward the second axial side A12 in the axial direction A1. Therefore, a portion of the bias magnet 7H on the second axial side A12 side is located on the second axial side A12 of the first teeth 12H. The bias magnet 7H is magnetized in the rotational direction C1. Specifically, the bias magnet 7H generates bias magnetic flux toward the bias magnetic flux passage member 8H. With the above configuration, magnetic flux from the bias magnet 7H flows efficiently through the thrust disk, the first teeth 12H, and the second teeth 13H.

[0116] The bias magnetic flux path member 8H has multiple steel plates stacked in the axial direction A1. The bias magnetic flux path member 8H has a yoke 14H and bias teeth 15H. The bias teeth 15H extend from the yoke 14H toward the axial direction R1, with their tips close to the outer peripheral surface of the thrust disk. The bias teeth 15H protrude toward the axial direction R1 from the bias magnetic flux path member 8H at the same position in the axial direction A1 as the first teeth 12H.

[0117] In the eighth embodiment, the same effects as in the first embodiment can be obtained.

[0118] Ninth Embodiment In the first embodiment, the magnetic bearing 1 is used alone. However, the magnetic bearing may be integrated with the motor to form a part of the bearingless motor. Such an example will be described below.

[0119] (1) Basic Configuration of Bearingless Motor A bearingless motor 21J according to a ninth embodiment will be described with reference to FIGS.

[0120] Figure 23 is a cross-sectional view of a bearingless motor 21J according to the ninth embodiment. As shown in Figure 23, the bearingless motor 21J mainly has a magnetic bearing 1J and a rotational drive mechanism 31J that rotates a rotor 3J of the magnetic bearing 1J. The magnetic bearing 1J and the rotational drive mechanism 31J are aligned in the axial direction A1, and in this embodiment, the magnetic bearing 1J is disposed on the first axial side A11.

[0121] (2) Magnetic Bearing Figure 24 is a plan view of a magnetic bearing 1J of a bearingless motor 21J. As shown in Figure 24, the magnetic bearing 1J has a stator 2J and a rotor 3J. The stator 2J has a magnetic support unit 4J. The magnetic support unit 4J is a thrust support stator having a plurality of magnetic circuit members 5J. The rotor 3J has a thrust disk 16J. The above configuration of the magnetic bearing 1J is the same as the basic configuration and basic operation of the magnetic bearing 1 of the first embodiment. Therefore, only the necessary parts will be explained below.

[0122] The magnetic bearing 1J further includes a cylindrical fixed member 32J. A plurality of magnetic circuit members 5J are fixed to the upper end of the fixed member 32J.

[0123] The rotor 3J has an annular shaft 17J. The thrust disk 16J is fixed to the upper end of the shaft 17J.

[0124] (3) Rotational Drive Mechanism Figure 25 is a plan view of the rotational drive mechanism 31J of the bearingless motor 21J. The rotational drive mechanism 31J is a two-axis (X-axis and Y-axis) actively controlled bearingless motor unit. As shown in Figure 25, the rotational drive mechanism 31J has a radially supported stator 34J and a radially supported rotor 35J.

[0125] The radial support stator 34J is fixed to the lower part of the fixed member 32J. The radial support stator 34J has a cylindrical frame 36J, a stator core 37J fixed to the inner peripheral surface of the frame 36J, motor windings 38J wound around multiple teeth of the stator core 37J, and radial windings 39J wound around multiple teeth of the stator core 37J. The motor windings 38J constitute a motor coil. The radial windings 39J constitute a radial coil.

[0126] The radial support rotor 35J is fixed to the lower end of the shaft 17J. The radial support rotor 35J is disposed radially inwardly and opposite to the radial support stator 34J.

[0127] The radial support rotor 35J has a rotor core 40J and a plurality of rotor magnets 41J. The rotor core 40J is fixed to the outer peripheral surface of the shaft 17J. The plurality of rotor magnets 41J form alternating north and south poles on the outer peripheral surface of the radial support rotor 35J. By applying an alternating current to the motor windings 38J that is rotationally synchronized with the rotor 3J, torque is generated around the axis of the radial support rotor 35J.

[0128] (4) Control Configuration of Magnetic Bearing Fig. 26 is a schematic block diagram showing the control configuration of the bearingless motor 21J. The control configuration of the bearingless motor 21J will be described using Fig. 26.

[0129] The bearingless motor system includes a bearingless motor 21J, a control device 51J, and an inverter 53J. The bearingless motor 21J further includes a position sensor 52J, as shown in FIG.

[0130] The control device 51J has, for example, a levitation control unit, a current control unit, and an attitude calculation unit. Each function of the control device 51J is realized, for example, by a computer. The bearingless motor system has, for example, a processing board made up of a printed circuit board or the like on which electronic circuits (electrical circuits) are printed. The processing board has, for example, a CPU (Central Processing Unit), memory, etc., and constitutes a computer. The CPU then executes a program stored in the memory, causing the computer to function as the control device 51J. Note that the control device 51J may also be a hardware circuit designed specifically to realize the above functions.

[0131] The position sensor 52J is a sensor that detects the displacement of the rotor 3.

[0132] The position sensors 52J are provided, for example, at five locations on the outer periphery of the thrust disk 16J.

[0133] The inverter 53J can supply current to a thrust winding 9J that is wound around a second tooth (not shown) to form a thrust coil 10J.

[0134] (5) Operation of Bearingless Motor (5-1) Rotor Rotation Operation The control device 51J controls the inverter 53J to supply three-phase AC current, which is rotationally synchronized with the rotor 3J, from the inverter 53J to the motor windings 38J. This generates torque around the axis R1 in the rotor 3J, causing the rotor 3J to rotate.

[0135] (5-2) Position Control Operation in the X- and Y-Axis Directions The control device 51J supplies current from the inverter 53J to the radial winding 39J based on the detection signal from the position sensor 52J. As a result, the position of the rotor 3J in the X- and Y-axis directions is controlled by the magnetic field generated from the radial winding 39J and the magnetic field generated from the rotor magnet 41J.

[0136] (5-3) Position Control Operation in the Z-Axis Direction The control device 51J causes the inverter 53J to supply current to the thrust winding 9J based on a detection signal from the position sensor 52J. As a result, the position of the rotor 3 in the axial direction A1 is controlled by the magnetic field generated by the thrust winding 9J and the magnetic field generated by a bias magnet (not shown). In this case, the control device 51J controls the inverter 53J so that all of the thrust windings 9J generate a thrust force on the same side in the axial direction A1 (the first axial side A11 or the second axial side A12).

[0137] (5-4) Position Control Operation in the θx-Axis and θy-Axis Directions The control device 51J causes the inverter 53J to supply current to the thrust winding 9J based on a detection signal from the position sensor 52J. As a result, the position of the rotor 3J in the θx-axis and θy-axis directions is controlled by the magnetic field generated by the thrust winding 9J and the magnetic field generated by the bias magnet. In this case, for example, two thrust windings 9J arranged consecutively in the rotation direction C1 are treated as a group, and the control device 51J controls the inverter 53J so that each group generates a thrust force independently.

[0138] (Modifications) The first to ninth embodiments are merely examples of various embodiments of the present disclosure. The first to ninth embodiments can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. In particular, the first to ninth embodiments can be combined as appropriate.

[0139] The bias magnet may be an electromagnet (iron core, windings).

[0140] The magnetic circuit members may be arranged at unequal intervals in the rotation direction C1.

[0141] The positions in the axial direction A1 of the lower surfaces of the first teeth 12 and the upper surfaces of the second teeth 13 do not have to coincide with each other. Furthermore, the first teeth 12 and the second teeth 13 may partially overlap when viewed in the axial direction A1.

[0142] The bias teeth 15 may be located on the lower side in the axial direction A1.

[0143] The magnetic bearing 1 is not limited to three-axis active control in the Z-axis, θx-axis, and θy-axis directions. The magnetic bearing may also perform five-axis active control in the X-axis, Y-axis, Z-axis, θx-axis, and θy-axis directions. The magnetic bearing may also perform only one-axis active control in the Z-axis direction. The magnetic bearing may also perform two-axis active control in the θx-axis and θy-axis directions.

[0144] A five-axis actively controlled bearingless motor may be configured by combining the magnetic bearing 1 with two two-axis actively controlled magnetic bearings and one motor, with the magnetic bearing 1 only performing single-axis active control in the Z-axis direction. Alternatively, a five-axis actively controlled bearingless motor may be configured by combining the magnetic bearing 1 with one two-axis actively controlled magnetic bearing and one two-axis actively controlled bearingless motor, with the magnetic bearing 1 only performing single-axis active control in the Z-axis direction.

[0145] (Aspects) The present specification discloses the following aspects.

[0146] A magnetic bearing (1, 1J) according to a first aspect includes a rotor (3, 3J) and a stator (2, 2J). The rotor (3, 3J) has a magnetic disk (16, 16A, 16J) that is rotatable in a rotational direction (C1) around an axis (R1). The stator (2, 2J) has a magnetic support unit (4, 4J) that is disposed radially opposite the rotor (3, 3J) and generates a magnetic support force on the rotor (3, 3J). The magnetic support unit (4, 4J) has first teeth (12, 12A, 12B, 12C, 12D, 12E, 12G, 12H) and second teeth (13, 13A, 13B, 13C, 13D, 13E, 13G, 13H) that are magnetic. The magnetic support unit (4, 4J) has magnets (7, 7A, 7B, 7C, 7D, 7E, 71E, 7G, 7H) that generate bias magnetic flux in the first teeth (12, 12A, 12B, 12C, 12D, 12E, 12G, 12H) and the second teeth (13, 13A, 13B, 13C, 13D, 13E, 13G, 13H). The magnetic support unit (4, 4J) has a coil (10, 10A, 10B, 10C, 10D, 10E, 10G, 10H, 10J) having a conductor portion (19, 19A, 19B, 19C, 19D, 19E, 19G, 19H) arranged between the first teeth (12, 12A, 12B, 12C, 12D, 12E, 12G, 12H) and the second teeth (13, 13A, 13B, 13C, 13D, 13E, 13G, 13H). The first teeth (12, 12A, 12B, 12C, 12D, 12E, 12G, 12H) and the second teeth (13, 13A, 13B, 13C, 13D, 13E, 13G, 13H) are positioned differently in the axial direction (A1).

[0147] According to this aspect, depending on the direction of the current flowing through the coils (10, 10A, 10B, 10C, 10D, 10E, 10G, 10H, 10J), a large force is applied to the disks (16, 16A, 16J) from one of the first teeth (12, 12A, 12B, 12C, 12D, 12E, 12G, 12H) and the second teeth (13, 13A, 13B, 13C, 13D, 13E, 13G, 13H), causing the disks (16, 16A, 16J) to move to one side in the axial direction (A1). Because a thrust supporting force can be generated with such a simple structure, the magnetic bearing (1, 1J) can be made smaller.

[0148] In the magnetic bearing (1, 1J) according to the second aspect, in the first aspect, the magnets (7, 7A, 7B, 7C, 7D, 7E, 71E, 7G) are arranged at different positions relative to the first teeth (12, 12A, 12B, 12C, 12D, 12E, 12G) and the second teeth (13, 13A, 13B, 13C, 13D, 13E, 13G) when viewed from the axial direction (A1).

[0149] According to this aspect, bias magnetic flux from the magnets (7, 7A, 7B, 7C, 7D, 7E, 71E, 7G) flows efficiently through the disks (16, 16A, 16J), the first teeth (12, 12A, 12B, 12C, 12D, 12E, 12G), and the second teeth (13, 13A, 13B, 13C, 13D, 13E, 13G).

[0150] In the magnetic bearing (1, 1J) according to the third aspect, in the first or second aspect, the magnets (7, 7A, 7B, 7C, 7D, 7E, 71E, 7G, 7H) are permanent magnets and are further magnetized in a direction perpendicular to the axial direction (A1).

[0151] According to this aspect, bias magnetic flux from the magnets (7, 7A, 7B, 7C, 7D, 7E, 71E, 7G, 7H) flows efficiently through the disks (16, 16A, 16J), the first teeth (12, 12A, 12B, 12C, 12D, 12E, 12G, 12H), and the second teeth (13, 13A, 13B, 13C, 13D, 13E, 13G, 13H).

[0152] In the magnetic bearing (1, 1J) according to the fourth aspect, in any of the first to third aspects, the first teeth (12, 12A, 12B, 12C, 12D, 12E, 12G, 12H) and the second teeth (13, 13A, 13B, 13C, 13D, 13E, 13G, 13H) are at different positions in the direction of rotation (C1).

[0153] According to this aspect, bias magnetic flux from the magnets (7, 7A, 7B, 7C, 7D, 7E, 71E, 7G, 7H) flows efficiently through the disks (16, 16A, 16J), the first teeth (12, 12A, 12B, 12C, 12D, 12E, 12G, 12H), and the second teeth (13, 13A, 13B, 13C, 13D, 13E, 13G, 13H).

[0154] In the magnetic bearing (1) according to the fifth aspect, in any of the first to fourth aspects, the lower surfaces of the first teeth (12, 12A, 12B, 12C, 12D, 12E, 12H) in the axial direction (A1) coincide with the upper surfaces of the second teeth (13, 13A, 13B, 13C, 13D, 13E, 13H) in the axial direction (A1).

[0155] According to this aspect, the thrust core (6) of the magnetic support unit (4, 4J) can be constructed using only two types of electromagnetic steel sheet laminates: an electromagnetic steel sheet laminate including the first teeth (12, 12A, 12B, 12C, 12D, 12E, 12H) and an electromagnetic steel sheet laminate including the second teeth (13, 13A, 13B, 13C, 13D, 13E, 13H). This reduces the number of shapes of the electromagnetic steel sheets, thereby increasing productivity. Furthermore, if the shapes of the first teeth (12) and the second teeth (13) are the same, the electromagnetic steel sheet laminate including the first teeth (12) and the electromagnetic steel sheet laminate including the second teeth (13) can have the same configuration, thereby further increasing productivity of the laminates.

[0156] The magnetic bearing (1, 1J) according to the sixth aspect is any of the first to fifth aspects, and further comprises a position sensor (52, 52J) that detects the position of the rotor (3, 3J) at a position radially opposite the disk (16, 16A, 16J).

[0157] According to this aspect, the position of the disk (16, 16A, 16J) in the axial direction (A1) can be controlled more accurately by the position sensor (52, 52J).

[0158] A bearingless motor (21J) according to a seventh aspect includes a magnetic bearing (1J) according to any one of the first to sixth aspects and a rotary drive mechanism (31J) that rotates a rotor (3J).

[0159] According to this aspect, the magnetic bearing (1J) is employed, so that the bearingless motor (21J) is made smaller.

[0160] A bearingless motor (21J) according to an eighth aspect is the seventh aspect, and further includes an active control mechanism (31J) that performs two-axis radial active control on the rotor (3J).

[0161] According to this aspect, the magnetic bearing (1J) is employed, so that the bearingless motor (21J) is made smaller.

[0162] DESCRIPTION OF SYMBOLS 1, 1J Magnetic bearing 2, 2J Stator 3, 3J Rotor 4, 4J Magnetic support unit 7, 7A, 7B, 7C, 7D, 7E, 71E, 7G, 7H Bias magnet (magnet) 10, 10A, 10B, 10C, 10D, 10E, 10G, 10H, 10J Thrust coil (coil) 12, 12A, 12B, 12C, 12D, 12E, 12G, 12H First teeth 13, 13A, 13B, 13C, 13D, 13E, 13G, 13H Second teeth 16, 16A, 16J Thrust disk (disk) 19, 19A, 19B, 19C, 19D, 19E, 19G, 19H Conductor 21J Bearingless motor 31J Rotation drive mechanism (active control mechanism) 52, 52J Position sensor A1 Axial direction R1 Axial

Claims

1. A magnetic bearing comprising: a rotor having a magnetic disk rotatable in a rotational direction around an axis; and a stator arranged radially opposite the rotor and having a magnetic support unit that generates a magnetic support force on the rotor, wherein the magnetic support unit has first and second teeth made of the magnetic material, a magnet that generates a bias magnetic flux in the first and second teeth, and a coil having a conductor portion arranged between the first and second teeth, wherein the first teeth and the second teeth are positioned differently in the axial direction.

2. The magnetic bearing according to claim 1, wherein the magnets are arranged at different positions relative to the first teeth and the second teeth when viewed from the axial direction.

3. A magnetic bearing according to claim 1 or 2, wherein the magnet is a permanent magnet and is magnetized in a direction perpendicular to the axial direction.

4. A magnetic bearing according to claim 1 or 2, wherein the first teeth and the second teeth are positioned differently in the rotational direction.

5. A magnetic bearing according to claim 1 or 2, wherein a lower surface of the first tooth in the axial direction coincides with an upper surface of the second tooth in the axial direction.

6. The magnetic bearing according to claim 1 or 2, further comprising a position sensor for detecting a position of the rotor, disposed at a position radially opposed to the disk.

7. A bearingless motor comprising: a magnetic bearing according to claim 1 or 2; and a rotary drive mechanism for rotating the rotor.

8. The bearingless motor according to claim 7, further comprising an active control mechanism for performing two-axis active control in the radial direction on the rotor.

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