Magnetic levitation motors and magnetic levitation pumps

Abstract

To provide a magnetic floating type dynamo-electric motor that actively controls a one shaft to a thrust direction, capable of securing a supporting force to a radial direction, and enhancing the support force of the thrust direction.SOLUTION: A magnetic floating type dynamo-electric motor 10 comprises: a fixing permanent magnet part 20 that is provided to a casing 11; and a rotational permanent magnet part 30 that supports a rotational shaft 12 in non-contact to a radial direction orthogonal to a shaft line C by a repulsive power with the fixing permanent magnet part 20 so as to be oppositely provided to the fixing permanent magnet part 20 in the rotational shaft 12. The fixing permanent magnet part 20 includes: a pair of first fixing permanent magnets 21 that is magnetized to the radial direction; and a pair of second fixing permanent magnets 22 that is magnetized in the opposite direction to the first fixing permanent magnets 21 in the radial direction. The rotational permanent magnet part 30 includes: a pair of first rotational permanent magnets 31 that is magnetized to an inverse direction with the first fixing permanent magnets 21 to the radial direction; and a pair of second rotational permanent magnets 32 that is magnetized to an inverse direction with the second fixing permanent magnets 22 to the radial direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a magnetic levitation motor and a magnetic levitation pump.

Background Art

[0002] As a bearingless motor that supports a rotating shaft without mechanically contacting a casing, a magnetic levitation motor that levitates and supports a rotating shaft by magnetism is known (see, for example, Patent Document 1). The magnetic levitation motor described in Patent Document 1 actively controls one axis in the thrust direction (γ-axis direction) and four axes in the radial direction (α-axis direction, β-axis direction, α-axis rotation, β-axis rotation) in order to control the levitation position of the rotating shaft with respect to the casing. However, in such a magnetic levitation motor, since it is necessary to actively control each of the five axes, the manufacturing cost becomes high. Therefore, so-called one-axis control, which actively controls only one axis in the thrust direction and passively controls the four axes in the radial direction, has been studied.

[0003] FIG. 22 is a cross-sectional view of a magnetic levitation motor in which conventional one-axis control is performed. This magnetic levitation motor includes a casing 90, a rotating shaft 91 and a motor unit 92 disposed in the casing 90. The motor unit 92 has a stator 92a provided at the axial center of the casing 90 and a rotor 92b provided at a position of the rotating shaft 91 facing the stator 92a.

[0004] The magnetic levitation motor further includes a pair of support coils 93 and a pair of annular fixed permanent magnets 94 provided in the casing 90, and a pair of annular rotating permanent magnets 95 attached to the rotating shaft 91. The fixed permanent magnets 94 are provided at both axial ends of the casing 90. The rotating permanent magnets 95 are provided facing the fixed permanent magnets 94 at both axial ends of the rotating shaft 91. The fixed permanent magnet 94 and the rotating permanent magnet 95 facing each other are magnetized so as to generate a repulsive force in the radial direction. This repulsive force acts on the rotating shaft 91 as a radial support force that supports the rotating shaft 91 in a non-contact manner with respect to the casing 90.

[0005] The support coils 93 are positioned on both axial sides of the stator 92a and wound around the rotation axis 91 in a circumferential direction. When current is applied to the support coils 93, the magnetic flux generated by the support coils 93 is superimposed on the magnetic fluxes of the fixed permanent magnets 94 and the rotating permanent magnets 95, causing a concentration of density in the magnetic field at both axial ends of the rotation axis 91. This concentration of density generates a support force that supports the rotation axis 91 in the thrust direction. Thus, by controlling the current applied to the support coils 93, one axis in the thrust direction of the rotation axis 91 can be actively controlled. Furthermore, the repulsive force generated between the fixed permanent magnets 94 and the rotating permanent magnets 95 allows for passive control of the four radial axes of the rotation axis 91. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2017-158325 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] In a magnetic levitation pump equipped with a magnetic levitation motor that performs the above-described single-axis control, a partition wall for protecting the casing 90 and the rotating shaft 91 from the transferred fluid is placed between the stationary permanent magnet 94 and the rotating permanent magnet 95. For this reason, it is necessary to create a large gap between the stationary permanent magnet 94 and the rotating permanent magnet 95. If the gap is made large, the repulsive force (magnetic force) between the stationary permanent magnet 94 and the rotating permanent magnet 95 weakens, and the radial support force of the rotating shaft 91 decreases. For this reason, in order to widen the gap, it is necessary to increase the repulsive force between the stationary permanent magnet 94 and the rotating permanent magnet 95 in order to ensure the radial support force of the rotating shaft 91.

[0008] However, if the repulsive force is increased, when the rotating permanent magnet 95 shifts to one side in the thrust direction relative to the fixed permanent magnet 94, the force pushing the rotating shaft 91 to that side increases. If this pushing force becomes greater than the supporting force that supports the rotating shaft 91 in the thrust direction, there is a risk that the rotating shaft 91 will no longer be able to be supported in the thrust direction.

[0009] This invention has been made in view of these circumstances, and aims to increase the thrust support force in a magnetic levitation motor that actively controls one axis in the thrust direction, while ensuring the radial support force. [Means for solving the problem]

[0010] (1) The present invention relates to a motor unit having a casing made of a magnetic material, a rotating shaft disposed within the casing and rotatable about a predetermined axis, a stator provided in the casing, and a rotor provided on the rotating shaft opposite the stator, a fixed permanent magnet unit provided in the casing, a rotating permanent magnet unit provided on the rotating shaft opposite the fixed permanent magnet unit and supporting the rotating shaft non-contact in a radial direction perpendicular to the axis by a repulsive force with the fixed permanent magnet unit, a support coil provided in the casing and wound around the axis, and a current applied to the support coil that controls the current applied to the support coil and superimposes the magnetic flux generated by the support coil onto the magnetic fluxes of the fixed permanent magnet unit and the rotating permanent magnet unit to provide a thrust support force along the axis. A magnetic levitation electric motor comprising: a control unit that acts on a rotating shaft; the fixed permanent magnet section comprises a pair of annular first fixed permanent magnets arranged in the thrust direction on either side of the stator and magnetized in the radial direction; and a pair of annular second fixed permanent magnets arranged on the stator side of each of the first fixed permanent magnets and magnetized in the opposite direction to the first fixed permanent magnets in the radial direction; and the rotating permanent magnet section comprises a pair of annular first rotating permanent magnets arranged opposite to each of the pair of first fixed permanent magnets and magnetized in the opposite direction to the first fixed permanent magnets in the radial direction; and a pair of annular second rotating permanent magnets arranged opposite to each of the pair of second fixed permanent magnets and magnetized in the opposite direction to the second fixed permanent magnets in the radial direction.

[0011] According to the magnetic levitation motor of the present invention, the repulsive force between the first fixed permanent magnet and the first rotating permanent magnet, and the repulsive force between the second fixed permanent magnet and the second rotating permanent magnet, allows the rotating shaft to be supported radially without contact. This increases the radial support force compared to the conventional method where the rotating shaft is supported only by the repulsive force between one set of fixed permanent magnets and one set of rotating permanent magnets. Therefore, even if the gap (clearance) between the fixed permanent magnet section and the rotating permanent magnet section becomes large, the radial support force of the rotating shaft can be secured.

[0012] Furthermore, the magnetic flux generated by the support coil is superimposed on the magnetic flux of one of the first fixed permanent magnets and the second fixed permanent magnet on each side of the stator in the thrust direction, and is canceled out by the magnetic flux of the other, and is superimposed on the magnetic flux of one of the first rotating permanent magnets and the second rotating permanent magnet, and is canceled out by the magnetic flux of the other. As a result, the magnetic flux density of the magnetic field is concentrated or concentrated on each side of the thrust direction. Consequently, the magnetic flux generated by the support coil flows between the superimposed first fixed permanent magnet and the second rotating permanent magnet (or between the superimposed second fixed permanent magnet and the first rotating permanent magnet), thereby generating a support force that supports the rotation axis in the thrust direction.

[0013] Furthermore, when the magnetic flux generated by the support coil applies a thrust-direction support force to the rotating shaft, a loop-shaped magnetic flux is generated in the fixed permanent magnet section, flowing in the order of first (or second) fixed permanent magnet → second (or first) fixed permanent magnet → gap with the rotating permanent magnet section → first (or second) fixed permanent magnet. This reduces leakage magnetic flux from the first and second fixed permanent magnets. Similarly, in the rotating permanent magnet section, a loop-shaped magnetic flux is generated, flowing in the order of first (or second) rotating permanent magnet → second (or first) rotating permanent magnet → gap with the fixed permanent magnet section → first (or second) rotating permanent magnet. This reduces leakage magnetic flux from the first and second rotating permanent magnets. As a result, the magnetic flux density of the magnetic flux flowing through the gap increases, thereby increasing the thrust-direction support force.

[0014] (2) Preferably, the fixed permanent magnet section further comprises a pair of annular third fixed permanent magnets arranged adjacent to the stator side of each of the first fixed permanent magnets and adjacent to the side opposite to the stator side of each of the second fixed permanent magnets, and magnetized in opposite directions to each other in the thrust direction, and the rotating permanent magnet section further comprises a pair of annular third rotating permanent magnets arranged opposite to each of the pair of third fixed permanent magnets, and magnetized in opposite directions to each other in the thrust direction and magnetized in the same direction as the opposing third fixed permanent magnets.

[0015] In this case, the repulsive force between the third fixed permanent magnet and the third rotating permanent magnet can further increase the radial support force of the rotating shaft. Also, when the magnetic flux generated by the support coil applies a thrust support force to the rotating shaft, in the fixed permanent magnet section, the third fixed permanent magnet facilitates the flow of magnetic flux from the first (or second) fixed permanent magnet to the second (or first) fixed permanent magnet, thereby further reducing the leakage magnetic flux from the first and second fixed permanent magnets. Similarly, in the rotating permanent magnet section, the third rotating permanent magnet facilitates the flow of magnetic flux from the first (or second) rotating permanent magnet to the second (or first) rotating permanent magnet, thereby further reducing the leakage magnetic flux from the first and second rotating permanent magnets. As a result, the magnetic flux density of the magnetic flux flowing through the gap becomes even larger, further increasing the thrust support force.

[0016] (3) The fixed permanent magnet section further comprises a pair of annular fourth fixed permanent magnets arranged adjacent to the opposite side of each first fixed permanent magnet and magnetized in opposite directions in the thrust direction, and a pair of annular fifth fixed permanent magnets arranged adjacent to the stator side of each second fixed permanent magnet and magnetized in opposite directions in the thrust direction, wherein each fourth fixed permanent magnet is magnetized in the opposite direction to the third fixed permanent magnet adjacent to the stator side of the adjacent first fixed permanent magnet, and each fifth fixed permanent magnet is magnetized in the opposite direction to the third fixed permanent magnet adjacent to the opposite side of the adjacent second fixed permanent magnet.

[0017] In this case, when the magnetic flux generated by the support coil applies a thrust-direction support force to the rotating shaft, a loop-shaped magnetic flux is generated in the fixed permanent magnet section, flowing in the order of fourth fixed permanent magnet → gap with the rotating permanent magnet section (or first fixed permanent magnet) → first fixed permanent magnet (or gap with the rotating permanent magnet section) → fourth fixed permanent magnet. Furthermore, a loop-shaped magnetic flux is generated in the fixed permanent magnet section, flowing in the order of fifth fixed permanent magnet → gap with the rotating permanent magnet section (or second fixed permanent magnet) → second fixed permanent magnet (or gap with the rotating permanent magnet section) → fifth fixed permanent magnet. As a result, the magnetic flux density of the magnetic flux flowing through the gaps becomes even larger, and the thrust-direction support force can be further increased.

[0018] (4) Preferably the rotating permanent magnet section further comprises a pair of annular fourth rotating permanent magnets arranged opposite to each of the pair of fourth fixed permanent magnets, magnetized in opposite directions in the thrust direction and magnetized in the same direction as the opposing fourth fixed permanent magnets, and a pair of annular fifth rotating permanent magnets arranged opposite to each of the pair of fifth fixed permanent magnets, magnetized in opposite directions in the thrust direction and magnetized in the same direction as the opposing fifth fixed permanent magnets.

[0019] In this case, when the magnetic flux generated by the support coil applies a thrust-direction support force to the rotating shaft, a loop-shaped magnetic flux is generated in the rotating permanent magnet section, flowing in the order of fourth rotating permanent magnet → gap with the fixed permanent magnet section (or first rotating permanent magnet) → first rotating permanent magnet (or gap with the fixed permanent magnet section) → fourth rotating permanent magnet. Furthermore, a loop-shaped magnetic flux is generated in the rotating permanent magnet section, flowing in the order of fifth rotating permanent magnet → gap with the fixed permanent magnet section (or second rotating permanent magnet) → second rotating permanent magnet (or gap with the fixed permanent magnet section) → fifth rotating permanent magnet. As a result, the magnetic flux density of the magnetic flux flowing through the gaps becomes even larger, and the thrust-direction support force can be further increased.

[0020] (5) From another perspective, the present invention is a magnetic levitation pump comprising a housing having a suction port and a discharge port for a transfer fluid, the magnetic levitation motor according to any one of (1) to (4) provided in the housing, an impeller provided at one end of the rotating shaft in the thrust direction, and a partition portion separating between the rotating shaft side and the casing side.

[0021] According to the magnetic levitation pump of the present invention, the same operational effects as those of the above magnetic levitation motor are achieved. In particular, in the magnetic levitation pump, since a partition portion for separating between the rotating shaft side and the casing side is arranged, the gap between the fixed permanent magnet portion and the rotating permanent magnet portion becomes larger, so that the above operational effects become more effective.

Effects of the Invention

[0022] According to the present invention, in a magnetic levitation motor that actively controls one axis in the thrust direction, it is possible to increase the supporting force in the thrust direction while ensuring the supporting force in the radial direction.

Brief Description of the Drawings

[0023] [Figure 1] It is a cross-sectional view of a magnetic levitation pump according to a first embodiment of the present invention. [Figure 2] It is an enlarged cross-sectional view of a part of the magnetic levitation motor. [Figure 3] It is a diagram showing a state in which a current is applied in one direction to the support coil of FIG. 2. [Figure 4] It is a diagram showing a state in which a current is applied in one direction to the support coil of FIG. 2. [Figure 5] It is a diagram showing a state in which a current is applied in one direction to the support coil of FIG. 2. [Figure 6] It is a diagram showing a state in which a current is applied in the other direction to the support coil of FIG. 2. [Figure 7] It is a diagram showing a state in which a current is applied in the other direction to the support coil of FIG. 2. [Figure 8] It is a diagram showing a state in which a current is applied in the other direction to the support coil of FIG. 2. [Figure 9] This is an enlarged cross-sectional view of a part of the magnetic levitation motor 10 according to a second embodiment of the present invention. [Figure 10] This figure shows the state in which current is applied in one direction to the support coil in Figure 9. [Figure 11] This figure shows the state in which current is applied in one direction to the support coil in Figure 9. [Figure 12] This figure shows the state in which current is applied in one direction to the support coil in Figure 9. [Figure 13] This figure shows the state where current is being applied to the support coil in Figure 9 in opposite directions. [Figure 14] This figure shows the state where current is being applied to the support coil in Figure 9 in opposite directions. [Figure 15] This figure shows the state where current is being applied to the support coil in Figure 9 in opposite directions. [Figure 16] This is an enlarged cross-sectional view of a part of the magnetic levitation motor 10 according to the third embodiment of the present invention. [Figure 17] This figure shows the state in which current is applied in one direction to the support coil shown in Figure 16. [Figure 18] This figure shows the state in which current is being applied to the support coil in Figure 16 in opposite directions. [Figure 19] This is an enlarged cross-sectional view of a part of the magnetic levitation motor 10 according to the fourth embodiment of the present invention. [Figure 20] This figure shows the state in which current is applied in one direction to the support coil in Figure 19. [Figure 21] This figure shows the state in which current is being applied to the support coil in Figure 19 in a different direction. [Figure 22] This is a cross-sectional view of a conventional magnetic levitation motor with single-axis control. [Modes for carrying out the invention]

[0024] Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings. <First Embodiment> [Magnetic levitation pump] Figure 1 is a cross-sectional view of a magnetic levitation pump according to a first embodiment of the present invention. In Figure 1, the magnetic levitation pump 1 of this embodiment (hereinafter also simply referred to as "pump 1") consists of, for example, a centrifugal pump. Pump 1 comprises a housing 2, a pump section 5, and a magnetic levitation motor 10 (hereinafter also simply referred to as "motor 10"). In this specification, the direction along the axis C of the motor 10 is referred to as the "axial direction," the left side of Figure 1 is referred to as the "one axial side," and the right side of Figure 1 is referred to as the "other axial side" (the same applies to Figures 2 to 21).

[0025] Housing 2 comprises a first housing 3 and a second housing 4 provided on one axial side of the first housing 3. The first housing 3 is formed in a substantially bottomed cylindrical shape with axis C as the center. Specifically, the first housing 3 comprises a cylindrical portion 3a, an annular first wall portion 3b fixed to one axial side of the cylindrical portion 3a, and a disc-shaped second wall portion 3c fixed to the other axial side of the cylindrical portion 3a.

[0026] The second housing 4 is formed in a substantially cylindrical shape with axis C as its center. The other axial end of the second housing 4 is connected to the first wall portion 3b of the first housing 3. An inlet 4a for drawing in the transfer fluid is formed at one axial end of the second housing 4. An outlet 4b for discharging the transfer fluid is formed on the outer circumferential surface of the second housing 4.

[0027] The pump section 5 consists of an impeller 6 and a partition wall section 7. The impeller 6 is positioned across the first housing 3 and the second housing 4. The impeller 6 is mounted integrally with the rotating shaft 12 of the electric motor 10 so as to be rotatable. As the impeller 6 rotates together with the rotating shaft 12, the transfer fluid drawn in from the suction port 4a is discharged from the discharge port 4b by centrifugal force.

[0028] The partition wall 7 separates the rotating shaft 12 side of the electric motor 10 from the casing 11 side. The partition wall 7 in this embodiment has a cylindrical first partition wall 7a, an annular second partition wall 7b, and a cylindrical third partition wall 7c, which are provided on the rotating shaft 12 side of the electric motor 10. The first partition wall 7a covers the inner circumferential surfaces of the rotating shaft 12 and the impeller 6. The second partition wall 7b is fixed to the other axial end of the first partition wall 7a. The second partition wall 7b covers the other axial end face of the rotating shaft 12. The third partition wall 7c covers the components on the rotating shaft 12 side of the electric motor 10 (rotating shaft 12, rotor 15, and rotating permanent magnet section 30) from the outside. One axial end of the third partition wall 7c is fixed to the impeller 6 in a closed state by the impeller 6. The other axial end of the third bulkhead 7c is fixed to the outer peripheral end of the second bulkhead 7b. As a result, the first to third bulkheads 7a to 7c rotate together with the impeller 6 and the rotation shaft 12.

[0029] The partition wall 7 of this embodiment further comprises a bottomed cylindrical fourth partition wall 7d and an annular flange 7e, both provided on the casing 11 side of the electric motor 10. The fourth partition wall 7d is positioned radially outward of the third partition wall 7c. The fourth partition wall 7d covers the components on the casing 11 side of the electric motor 10 (casing 11, stator 14, support coil 17, and fixed permanent magnet section 20) from the inside. The flange 7e is provided at one axial end of the fourth partition wall 7d and is held in a sandwiched state between the first housing 3 and the second housing 4. As a result, the fourth partition wall 7d and the flange 7e are fixed to the casing 11 of the electric motor 10.

[0030] Flow channels 8a, 8b, and 8c are continuously formed on the inner circumference of the first partition wall 7a, between the bottom surface (other axial end surface) of the second partition wall 7b and the fourth partition wall 7d, and between the outer circumference of the third partition wall 7c and the inner circumference of the fourth partition wall 7d, respectively, through which the transported fluid flows. Flow channel 8a functions as a through-hole for returning the transported fluid that has flowed through flow channels 8c and 8b to the impeller 6 side. By having the transported fluid flow through flow channel 8a, the axial disturbance force generated when the transported fluid is pumped by the impeller 6 can be suppressed. In addition, the transported fluid flowing through flow channel 8c is heated by fluid friction, but by returning this heated transported fluid to the impeller 6 side through flow channel 8a, the rise in temperature inside the pump section 5 can be suppressed. Furthermore, the first to fourth partition walls 7a to 7d protect the respective components on the rotating shaft 12 side and the casing 11 side from the transported fluid flowing through each of the flow channels 8a, 8b, and 8c.

[0031] [Magnetic levitation motor] The magnetic levitation motor 10 rotates the impeller 6. The magnetic levitation motor 10 comprises a casing 11, a rotating shaft 12, a motor section 13, a fixed permanent magnet section 20, a rotating permanent magnet section 30, a support coil 17, a sensor 18, and a control section 19. Components 11 to 17 of the magnetic levitation motor 10, excluding the sensor 18 and the control section 19, are housed within the housing 2.

[0032] The casing 11 is made of a magnetic material. The casing 11 of this embodiment has a magnetic cylinder portion 11a formed in a cylindrical shape with axis C as the center, an annular first magnetic wall portion 11b fixed to one axial side of the magnetic cylinder portion 11a, and an annular second magnetic wall portion 11c fixed to the other axial side of the magnetic cylinder portion 11a.

[0033] The outer circumferential surface of the magnetic cylindrical portion 11a is fitted to the inner circumferential surface of the cylindrical portion 3a of the first housing 3. The first magnetic wall portion 11b is arranged along the inner surface of the first wall portion 3b of the first housing 3. The second magnetic wall portion 11c is arranged along the inner surface of the second wall portion 3c of the first housing 3. A substantially cylindrical support portion 11d is formed on the inner circumferential side of the first magnetic wall portion 11b, projecting in the other direction in the axial direction. Similarly, a cylindrical support portion 11e is formed on the inner circumferential side of the second magnetic wall portion 11c, projecting in one direction in the axial direction.

[0034] The rotating shaft 12 is made of a cylindrical magnetic material and is rotatably arranged within the casing 11 around axis C. One axial end of the rotating shaft 12 is located within the support portion 11d of the first magnetic wall portion 11b. The other axial end of the rotating shaft 12 is located within the support portion 11e of the second magnetic wall portion 11c. An impeller 6 is fixed to one axial end face of the rotating shaft 12. As a result, rotating the rotating shaft 12 around axis C causes the impeller 6 to rotate around axis C.

[0035] The motor unit 13 includes a stator 14 provided at the axial center of the inner circumferential surface of the magnetic cylinder 11a, and a rotor 15 provided on the outer circumferential surface of the rotating shaft 12, opposite the stator 14. The stator 14 includes a fixed magnetic part 14a made of a magnetic material such as iron, and a winding 14b wound around the fixed magnetic part 14a. The rotor 15 has a plurality of permanent magnets 15a arranged along the circumferential direction of the rotating shaft 12. The winding 14b of the stator 14 is connected to a power supply (not shown) via a control unit 19. When current is applied to the winding 14b of the stator 14, a rotating magnetic field is generated, causing the rotor 15 to rotate together with the rotating shaft 12.

[0036] [Fixed permanent magnet section] Figure 2 is an enlarged cross-sectional view of a part of the magnetic levitation motor 10. As shown in Figure 2, the fixed permanent magnet section 20 is composed of a plurality of permanent magnets provided in the casing 11. The fixed permanent magnet section 20 in this embodiment has a first fixed permanent magnet 21, a second fixed permanent magnet 22, a third fixed permanent magnet 23, a fourth fixed permanent magnet 24, and a fifth fixed permanent magnet 25. Each of the fixed permanent magnets 21, 22, 23, 24, and 25 is formed in an annular shape. The radial thickness of each of the fixed permanent magnets 21, 22, 23, 24, and 25 is the same.

[0037] The first fixed permanent magnets 21 are arranged in pairs in the thrust direction (axial direction) along the axis C, sandwiching the stator 14 of the motor unit 13. The pair of first fixed permanent magnets 21 consists of a first fixed permanent magnet 21A that is fitted and fixed to the inner circumferential surface of the support portion 11d on one side in the thrust direction, and a first fixed permanent magnet 21B that is fitted and fixed to the inner circumferential surface of the support portion 11e on the other side in the thrust direction. The first fixed permanent magnets 21 are magnetized in the radial direction (radial direction) perpendicular to the axis C. In this embodiment, the first fixed permanent magnets 21 are magnetized such that the outer circumference side in the radial direction is the N pole and the inner circumference side in the radial direction is the S pole.

[0038] The second permanent magnets 22 are arranged in pairs, separated from each other on the stator 14 side of each first permanent magnet 21. Each pair of second permanent magnets 22 consists of a second permanent magnet 22A, which is separated from the first permanent magnet 21A on the other side in the thrust direction, and a second permanent magnet 22B, which is separated from the third permanent magnet 23B on one side in the thrust direction. The second permanent magnet 22A is fitted and fixed to the inner circumferential surface of the support portion 11d. The second permanent magnet 22B is fitted and fixed to the inner circumferential surface of the support portion 11e.

[0039] The second permanent magnet 22 is magnetized in the opposite direction to the first permanent magnet 21 in the radial direction. In this embodiment, the second permanent magnet 22 is magnetized such that the outer circumference in the radial direction is the south pole and the inner circumference in the radial direction is the north pole. The length of the second permanent magnet 22 in the thrust direction is not particularly limited, but in this embodiment it is the same as the length of the first permanent magnet 21 in the thrust direction.

[0040] The third permanent magnets 23 are arranged in pairs, adjacent to the stator 14 side of each first permanent magnet 21 and adjacent to the side opposite to the stator 14 (hereinafter also referred to as the anti-stator 14 side) of each second permanent magnet 22. The pair of third permanent magnets 23 consists of a third permanent magnet 23A arranged adjacent to the other side in the thrust direction of the first permanent magnet 21A, and a third permanent magnet 23B arranged adjacent to one side in the thrust direction of the first permanent magnet 21B. The third permanent magnet 23A is fitted and fixed to the inner circumferential surface of the support portion 11d. The third permanent magnet 23B is fitted and fixed to the inner circumferential surface of the support portion 11e.

[0041] The third fixed permanent magnets 23A and 23B are magnetized in opposite directions in the thrust direction. In this embodiment, the third fixed permanent magnet 23A is magnetized such that one side in the thrust direction is the south pole and the other side is the north pole. The third fixed permanent magnet 23B is magnetized such that one side in the thrust direction is the north pole and the other side is the south pole. The length of the third fixed permanent magnet 23 in the thrust direction is not particularly limited, but in this embodiment it is shorter than the length of the first fixed permanent magnet 21 in the thrust direction.

[0042] The fourth permanent magnets 24 are arranged in pairs adjacent to each first permanent magnet 21 on the side opposite to the stator 14. Each pair of fourth permanent magnets 24 consists of a fourth permanent magnet 24A arranged adjacent to one side in the thrust direction of the first permanent magnet 21A, and a fourth permanent magnet 24B arranged adjacent to the other side in the thrust direction of the first permanent magnet 21B. The fourth permanent magnet 24A is fitted and fixed to the inner circumferential surface of the support portion 11d. The fourth permanent magnet 24B is fitted and fixed to the inner circumferential surface of the support portion 11e.

[0043] The fourth fixed permanent magnets 24A and 24B are magnetized in opposite directions to each other in the thrust direction. Furthermore, the fourth fixed permanent magnet 24A is magnetized in the opposite direction to the third fixed permanent magnet 23A, which is adjacent to the first fixed permanent magnet 21A on the stator 14 side. Similarly, the fourth fixed permanent magnet 24B is magnetized in the opposite direction to the third fixed permanent magnet 23B, which is adjacent to the first fixed permanent magnet 21B on the stator 14 side.

[0044] In this embodiment, the fourth fixed permanent magnet 24A is magnetized such that one side in the thrust direction is the north pole and the other side in the thrust direction is the south pole. The fourth fixed permanent magnet 24B is magnetized such that one side in the thrust direction is the south pole and the other side in the thrust direction is the north pole. The length of the fourth fixed permanent magnet 24 in the thrust direction is not particularly limited, but in this embodiment it is shorter than the length of the third fixed permanent magnet 23 in the thrust direction.

[0045] The fifth permanent magnets 25 are arranged in pairs adjacent to each second permanent magnet 22 on the stator 14 side. Each pair of fifth permanent magnets 25 consists of a fifth permanent magnet 25A arranged adjacent to the other side in the thrust direction of the second permanent magnet 22A, and a fifth permanent magnet 25B arranged adjacent to one side in the thrust direction of the second permanent magnet 22B. The fifth permanent magnet 25A is fitted and fixed to the inner circumferential surface of the support portion 11d. The fifth permanent magnet 25B is fitted and fixed to the inner circumferential surface of the support portion 11e.

[0046] The fifth permanent magnets 25A and 25B are magnetized in opposite directions to each other in the thrust direction. Furthermore, the fifth permanent magnet 25A is magnetized in the opposite direction to the third permanent magnet 23A, which is adjacent to the second permanent magnet 22A on the side opposite the stator 14. Similarly, the fifth permanent magnet 25B is magnetized in the opposite direction to the third permanent magnet 23B, which is adjacent to the second permanent magnet 22B on the side opposite the stator 14.

[0047] In this embodiment, the fifth fixed permanent magnet 25A is magnetized such that one side in the thrust direction is the north pole and the other side in the thrust direction is the south pole. The fifth fixed permanent magnet 25B is magnetized such that one side in the thrust direction is the south pole and the other side in the thrust direction is the north pole. The length of the fifth fixed permanent magnet 25 in the thrust direction is not particularly limited, but in this embodiment it is the same as the length of the fourth fixed permanent magnet 24 in the thrust direction.

[0048] [Rotating permanent magnet section] The rotating permanent magnet section 30 is composed of a plurality of permanent magnets provided on the outer circumferential surface of the rotating shaft 12 so as to face the fixed permanent magnet section 20. The rotating permanent magnet section 30 in this embodiment has a first rotating permanent magnet 31, a second rotating permanent magnet 32, and a third rotating permanent magnet 33. Each of the rotating permanent magnets 31, 32, and 33 is formed in an annular shape. The radial thickness of each of the rotating permanent magnets 31, 32, and 33 is the same.

[0049] The first rotating permanent magnets 31 are arranged in pairs so as to face each of the pair of first fixed permanent magnets 21. Each pair of first rotating permanent magnets 31 consists of a first rotating permanent magnet 31A that is fitted and fixed to the outer circumferential surface of one end of the rotating shaft 12 in the thrust direction, and a first rotating permanent magnet 31B that is fitted and fixed to the outer circumferential surface of the other end of the rotating shaft 12 in the thrust direction. The first rotating permanent magnet 31A is positioned facing the first fixed permanent magnet 21A. The first rotating permanent magnet 31B is positioned facing the first fixed permanent magnet 21B.

[0050] The first rotating permanent magnet 31 is magnetized in the opposite direction to the first fixed permanent magnet 21 in the radial direction. In this embodiment, the first rotating permanent magnet 31 is magnetized such that the outer circumference in the radial direction is the south pole and the inner circumference in the radial direction is the north pole. The length of the first rotating permanent magnet 31 in the thrust direction is not particularly limited, but in this embodiment it is longer than the length of the first fixed permanent magnet 21 in the thrust direction. As a result, the south pole of the first rotating permanent magnet 31 is positioned opposite the south pole of the first fixed permanent magnet 21 and the south pole of the fourth fixed permanent magnet 24.

[0051] The second rotating permanent magnets 32 are arranged in pairs so as to face each of the pair of second fixed permanent magnets 22. Each pair of second rotating permanent magnets 32 consists of a second rotating permanent magnet 32A positioned opposite the second fixed permanent magnet 22A, and a second rotating permanent magnet 32B positioned opposite the second fixed permanent magnet 22B. The second rotating permanent magnet 32A is positioned apart on the other side in the thrust direction of the first rotating permanent magnet 31A and is fitted and fixed to the outer circumferential surface of the rotating shaft 12. The second rotating permanent magnet 32B is positioned apart on one side in the thrust direction of the first rotating permanent magnet 31B and is fitted and fixed to the outer circumferential surface of the rotating shaft 12.

[0052] The second rotating permanent magnet 32 ​​is magnetized in the opposite direction to the second fixed permanent magnet 22 in the radial direction. In this embodiment, the second rotating permanent magnet 32 ​​is magnetized such that the outer circumference in the radial direction is the north pole and the inner circumference in the radial direction is the south pole. The length of the second rotating permanent magnet 32 ​​in the thrust direction is not particularly limited, but in this embodiment it is longer than the length of the second fixed permanent magnet 22 in the thrust direction. As a result, the north pole of the second rotating permanent magnet 32 ​​is positioned opposite the north pole of the first fixed permanent magnet 21 and the north pole of the fifth fixed permanent magnet 25.

[0053] The third rotating permanent magnet 33 is arranged in pairs so as to face each of the pair of third fixed permanent magnets 23. The pair of third rotating permanent magnets 33 consists of a third rotating permanent magnet 33A positioned facing the third fixed permanent magnet 23A, and a third rotating permanent magnet 33B positioned facing the third fixed permanent magnet 23B. The third rotating permanent magnet 33A is positioned adjacent to the other side in the thrust direction of the first rotating permanent magnet 31A and adjacent to one side in the thrust direction of the second rotating permanent magnet 32A, and is fitted and fixed to the outer circumferential surface of the rotating shaft 12. The third rotating permanent magnet 33B is positioned adjacent to one side in the thrust direction of the first rotating permanent magnet 31B and adjacent to the other side in the thrust direction of the second rotating permanent magnet 32B, and is fitted and fixed to the outer circumferential surface of the rotating shaft 12.

[0054] The third rotating permanent magnets 33A and 33B are magnetized in opposite directions in the thrust direction. Furthermore, the third rotating permanent magnet 33A is magnetized in the same direction as the opposing third fixed permanent magnet 23A. Similarly, the third rotating permanent magnet 33B is magnetized in the same direction as the opposing third fixed permanent magnet 23B. In this embodiment, the third rotating permanent magnet 33A is magnetized such that one side in the thrust direction is the south pole and the other side is the north pole. The third rotating permanent magnet 33B is magnetized such that one side in the thrust direction is the north pole and the other side is the south pole. The length of the third rotating permanent magnet 33 in the thrust direction is not particularly limited, but in this embodiment it is slightly shorter than the length of the third fixed permanent magnet 23 in the thrust direction.

[0055] With the above configuration, repulsive forces act between the first fixed permanent magnet 21 and the first rotating permanent magnet 31, between the second fixed permanent magnet 22 and the second rotating permanent magnet 32, and between the third fixed permanent magnet 23 and the third rotating permanent magnet 33. In addition, repulsive forces act between the south pole of the fourth fixed permanent magnet 24 and the south pole of the first rotating permanent magnet 31, and between the north pole of the fifth fixed permanent magnet 25 and the north pole of the second rotating permanent magnet 32. Due to these repulsive forces, an annular gap (gap) G is formed between the opposing first to fifth fixed permanent magnets 21 to 25 and the first to third rotating permanent magnets 31 to 33. These repulsive forces then act on the rotating shaft 12 as a supporting force Fr that supports the rotating shaft 12 in the radial direction. As a result, the rotating shaft 12 is supported radially and non-contact with the casing 11 by the supporting force Fr.

[0056] [Support coil] The support coils 17 are for applying a thrust-direction support force to the rotating shaft 12. The support coils 17 are provided in pairs within the casing 11, sandwiching the stator 14 of the motor section 13 in the thrust direction. The pair of support coils 17 consists of a support coil 17A positioned at the corner between the magnetic cylindrical section 11a and the first magnetic wall section 11b on one side in the thrust direction, and a support coil 17B positioned at the corner between the magnetic cylindrical section 11a and the second magnetic wall section 11c on the other side in the thrust direction.

[0057] The support coils 17A and 17B are each positioned at a distance from the stator 14 in the thrust direction. The support coils 17A and 17B are each wound around axis C along the magnetic cylinder portion 11a. The support coils 17A and 17B are each connected to a power supply (not shown) via a control unit 19 (see Figure 1).

[0058] [Support force on one side in the thrust direction] Figures 3 to 5 show the state in which current is applied to the support coil 17 in one direction. For convenience, the direction of the magnetic flux within each magnet is indicated by an arrow in Figures 3 to 5 for each fixed permanent magnet 21 to 25 and each rotating permanent magnet 31 to 33 (the same applies to Figures 6 to 8, 10 to 15, 17 to 18, and 20 to 21). As shown in Figure 3, when a DC current is applied to the support coil 17 in the direction shown, a magnetic flux Ψc1 is generated by the support coil 17. The magnetic flux Ψc1 flows in a loop in the following order: magnetic cylinder portion 11a, first magnetic wall portion 11b, fixed permanent magnet portion 20 on one side in the thrust direction, rotating permanent magnet portion 30 on one side in the thrust direction, rotating shaft 12, rotating permanent magnet portion 30 on the other side in the thrust direction, fixed permanent magnet portion 20 on the other side in the thrust direction, second magnetic wall portion 11c, and magnetic cylinder portion 11a.

[0059] In this case, the magnetic flux Ψc1 is canceled out by the magnetic flux Ψ21a of the first fixed permanent magnet 21A on one side in the thrust direction and superimposed on the magnetic flux Ψ22a of the second fixed permanent magnet 22A. As a result, the magnetic flux density of the magnetic field becomes sparse at the first fixed permanent magnet 21A and dense at the second fixed permanent magnet 22A. Furthermore, the magnetic flux Ψc1 is superimposed by the magnetic flux Ψ31a of the first rotating permanent magnet 31A on one side in the thrust direction and canceled out by the magnetic flux Ψ32a of the second rotating permanent magnet 32A. As a result, the magnetic flux density of the magnetic field becomes dense at the first rotating permanent magnet 31A and sparse at the second rotating permanent magnet 32A.

[0060] On the other hand, the magnetic flux Ψc1 is canceled out by the magnetic flux Ψ31b of the first rotating permanent magnet 31B on the other side in the thrust direction and superimposed on the magnetic flux Ψ32b of the second rotating permanent magnet 32B. As a result, the magnetic flux density of the magnetic field becomes sparse at the first rotating permanent magnet 31B and dense at the second rotating permanent magnet 32B. Furthermore, the magnetic flux Ψc1 is superimposed on the magnetic flux Ψ21b of the first fixed permanent magnet 21B on the other side in the thrust direction and canceled out by the magnetic flux Ψ22b of the second fixed permanent magnet 22B. As a result, the magnetic flux density of the magnetic field becomes dense at the first fixed permanent magnet 21B and sparse at the second fixed permanent magnet 22B.

[0061] As described above, due to the occurrence of density variations in the magnetic flux density of the magnetic field on both sides of the thrust direction, most of the magnetic flux Ψc1 flows as shown in Figure 4. Specifically, most of the magnetic flux Ψc1 on one side of the thrust direction flows from the second fixed permanent magnet 22A toward the first rotating permanent magnet 31A. Also, most of the magnetic flux Ψc1 on the other side of the thrust direction flows from the second rotating permanent magnet 32B toward the first fixed permanent magnet 21B. As a result, at the first rotating permanent magnet 31A and the second rotating permanent magnet 32B, the magnetic flux lines of the magnetic flux Ψc1 are inclined from their respective outer surfaces toward the other side of the gap G in the thrust direction, so a supporting force Fs1 acts on the rotation axis 12 toward the other side of the thrust direction toward which the magnetic flux lines are directed.

[0062] In this embodiment, the support force Fs1 can be increased by the first to fifth fixed permanent magnets 21 to 25 and the first to third rotating permanent magnets 31 to 33. The reason for this will be explained using Figure 5. As shown in Figure 5, on one side in the thrust direction, the magnetic fluxes Ψ21a, Ψ22a, and Ψ23a of the first to third fixed permanent magnets 21A to 23A generate a loop-shaped magnetic flux Ψ20a that flows clockwise in the figure, spanning the inner circumference of these fixed permanent magnets 21A to 23A and the outer circumference of the gap G. Also on one side in the thrust direction, the magnetic fluxes Ψ31a, Ψ32a, and Ψ33a of the first to third rotating permanent magnets 31A to 33A generate a loop-shaped magnetic flux Ψ30a that flows counterclockwise in the figure, spanning the outer circumference of these rotating permanent magnets 31A to 33A and the inner circumference of the gap G. Furthermore, on one side in the thrust direction, the magnetic fluxes Ψ22a and Ψ25a of the second and fifth fixed permanent magnets 22A and 25A generate a loop-shaped magnetic flux Ψ27a that flows in a counterclockwise direction as shown in the figure, spanning the inner circumference of these fixed permanent magnets 22A and 25A and the outer circumference of the gap G.

[0063] The generation of a loop-shaped magnetic flux Ψ20a reduces the leakage flux from the first fixed permanent magnet 21A and the second fixed permanent magnet 22A, which are located at both ends in the thrust direction among the first to third fixed permanent magnets 21A to 23A. Similarly, the generation of a loop-shaped magnetic flux Ψ30a reduces the leakage flux from the first rotating permanent magnet 31A and the second rotating permanent magnet 32A, which are located at both ends in the thrust direction among the first to third rotating permanent magnets 31A to 33A. Furthermore, the generation of a loop-shaped magnetic flux Ψ27a makes it easier for magnetic flux Ψc1 to flow between the two adjacent loop-shaped magnetic fluxes Ψ20a and Ψ27a in the thrust direction. As a result, the magnetic flux density of magnetic flux Ψc1 flowing through the gap G on one side in the thrust direction increases, thereby increasing the support force Fs1.

[0064] On the other side of the thrust direction, the magnetic fluxes Ψ21b, Ψ22b, and Ψ23b of the first to third fixed permanent magnets 21B to 23B generate a loop-shaped magnetic flux Ψ20b that flows counterclockwise in the figure, spanning the inner circumference of these fixed permanent magnets 21B to 23B and the outer circumference of the gap G. Also on the other side of the thrust direction, the magnetic fluxes Ψ31b, Ψ32b, and Ψ33b of the first to third rotating permanent magnets 31B to 33B generate a loop-shaped magnetic flux Ψ30b that flows clockwise in the figure, spanning the outer circumference of these rotating permanent magnets 31B to 33B and the inner circumference of the gap G. Furthermore, on the other side in the thrust direction, the magnetic fluxes Ψ21b and Ψ24b of the first and fourth fixed permanent magnets 21B and 24B generate a loop-shaped magnetic flux Ψ26b that flows in a clockwise direction in the figure, spanning the inner circumference of these fixed permanent magnets 21B and 24B and the outer circumference of the gap G.

[0065] The generation of a loop-shaped magnetic flux Ψ20b reduces the leakage flux from the first fixed permanent magnet 21B and the second fixed permanent magnet 22B, which are located at both ends in the thrust direction among the first to third fixed permanent magnets 21B to 23B. Furthermore, the generation of a loop-shaped magnetic flux Ψ30b reduces the leakage flux from the first rotating permanent magnet 31B and the second rotating permanent magnet 32B, which are located at both ends in the thrust direction among the first to third rotating permanent magnets 31B to 33B. Additionally, the generation of a loop-shaped magnetic flux Ψ26b makes it easier for magnetic flux Ψc1 to flow between the two adjacent loop-shaped magnetic fluxes Ψ20b and Ψ26b in the thrust direction. As a result, the magnetic flux density of the magnetic flux Ψc1 flowing through the gap G on the other side of the thrust direction also increases, further increasing the support force Fs1.

[0066] [Support force on the other side in the thrust direction] Figures 6 to 8 show the state in which current is applied to the support coil 17 in opposite directions. As shown in Figure 6, when a DC current is applied to the support coil 17 in the direction shown, a magnetic flux Ψc2 is generated by the support coil 17. The magnetic flux Ψc2 flows in a loop in the following order: magnetic cylinder portion 11a, second magnetic wall portion 11c, fixed permanent magnet portion 20 on the other side in the thrust direction, rotating permanent magnet portion 30 on the other side in the thrust direction, rotating shaft 12, rotating permanent magnet portion 30 on one side in the thrust direction, fixed permanent magnet portion 20 on one side in the thrust direction, first magnetic wall portion 11b, and magnetic cylinder portion 11a.

[0067] In this case, the magnetic flux Ψc2 is canceled out by the magnetic flux Ψ21b of the first fixed permanent magnet 21B on the other side in the thrust direction and superimposed on the magnetic flux Ψ22b of the second fixed permanent magnet 22B. As a result, the magnetic flux density of the magnetic field becomes sparse at the first fixed permanent magnet 21B and dense at the second fixed permanent magnet 22B. Furthermore, the magnetic flux Ψc2 is superimposed by the magnetic flux Ψ31b of the first rotating permanent magnet 31B on the other side in the thrust direction and canceled out by the magnetic flux Ψ32b of the second rotating permanent magnet 32B. As a result, the magnetic flux density of the magnetic field becomes dense at the first rotating permanent magnet 31B and sparse at the second rotating permanent magnet 32B.

[0068] On the other hand, the magnetic flux Ψc2 is canceled out by the magnetic flux Ψ31a of the first rotating permanent magnet 31A on one side in the thrust direction and superimposed on the magnetic flux Ψ32a of the second rotating permanent magnet 32A. As a result, the magnetic flux density of the magnetic field becomes sparse at the first rotating permanent magnet 31A and dense at the second rotating permanent magnet 32A. Also, the magnetic flux Ψc2 is superimposed on the magnetic flux Ψ21a of the first fixed permanent magnet 21A on one side in the thrust direction and canceled out by the magnetic flux Ψ32a of the second rotating permanent magnet 32A. As a result, the magnetic flux density of the magnetic field becomes dense at the first fixed permanent magnet 21A and sparse at the second rotating permanent magnet 32A.

[0069] As described above, due to the occurrence of density variations in the magnetic flux density of the magnetic field on both the other and one side of the thrust direction, most of the magnetic flux Ψc2 flows as shown in Figure 7. That is, most of the magnetic flux Ψc2 on the other side of the thrust direction flows from the second fixed permanent magnet 22B toward the first rotating permanent magnet 31B. Also, most of the magnetic flux Ψc2 on the one side of the thrust direction flows from the second rotating permanent magnet 32A toward the first fixed permanent magnet 21A. As a result, at the first rotating permanent magnet 31B and the second rotating permanent magnet 32A, the magnetic flux lines of the magnetic flux Ψc2 are inclined from their respective outer surfaces toward one side of the gap G in the thrust direction, so a supporting force Fs2 acts on the rotation axis 12 toward the one side of the thrust direction toward which the magnetic flux lines are directed.

[0070] In this embodiment, the support force Fs2 can be increased by the first to fifth fixed permanent magnets 21 to 25 and the first to third rotating permanent magnets 31 to 33. The reason for this will be explained using Figure 8. As shown in Figure 8, on one side in the thrust direction, loop-shaped magnetic flux Ψ20a and loop-shaped magnetic flux Ψ30a are generated, similar to the case shown in Figure 5. Furthermore, on one side in the thrust direction, the magnetic fluxes Ψ21a and Ψ24a of the first and fourth fixed permanent magnets 21A and 24A generate a loop-shaped magnetic flux Ψ26a that flows in a counterclockwise direction in the figure, spanning the inner circumference of these fixed permanent magnets 21A and 24A and the outer circumference of the gap G.

[0071] The generation of a loop-shaped magnetic flux Ψ20a reduces the leakage magnetic flux from the first fixed permanent magnet 21A and the second fixed permanent magnet 22A. Furthermore, the generation of a loop-shaped magnetic flux Ψ30a reduces the leakage magnetic flux from the first rotating permanent magnet 31A and the second rotating permanent magnet 32A. Additionally, the generation of a loop-shaped magnetic flux Ψ26a makes it easier for magnetic flux Ψc2 to flow between two adjacent loop-shaped magnetic fluxes Ψ26a and Ψ20a in the thrust direction. As a result, the magnetic flux density of magnetic flux Ψc2 flowing through the gap G on one side of the thrust direction increases, thereby increasing the support force Fs1.

[0072] On the other side of the thrust direction, loop-shaped magnetic fluxes Ψ20b and Ψ30b are generated, similar to the case shown in Figure 5. Furthermore, on the other side of the thrust direction, the magnetic fluxes Ψ22b and Ψ25b of the second and fifth fixed permanent magnets 22B and 25B generate a loop-shaped magnetic flux Ψ27b that flows in a clockwise direction in the figure, spanning the inner circumference of these fixed permanent magnets 22B and 25B and the outer circumference of the gap G.

[0073] The generation of a loop-shaped magnetic flux Ψ20b reduces the leakage magnetic flux from the first fixed permanent magnet 21B and the second fixed permanent magnet 22B. Furthermore, the generation of a loop-shaped magnetic flux Ψ30b reduces the leakage magnetic flux from the first rotating permanent magnet 31B and the second rotating permanent magnet 32B. Additionally, the generation of a loop-shaped magnetic flux Ψ27b makes it easier for magnetic flux Ψc2 to flow between two adjacent loop-shaped magnetic fluxes Ψ27b and Ψ20b in the thrust direction. As a result, the magnetic flux density of the magnetic flux Ψc2 flowing through the gap G on the other side of the thrust direction also increases, further enhancing the support force Fs2.

[0074] [Sensor] In Figure 1, the sensor 18 is attached to the second wall 3c of the housing 2. The sensor 18 detects the thrust position of the rotation axis 12 relative to the casing 11. The sensor 18 is a displacement sensor that detects the displacement of a sensor target (not shown) provided at the other end of the rotation axis 12 in the thrust direction. The sensor 18 is connected to the control unit 19. The detection signal from the sensor 18 is input to the control unit 19.

[0075] [Control Unit] The control unit 19 is configured with a computer including a CPU. The control unit 19 is located on the outside of the housing 2. The control unit 19 controls the current supplied to the winding 14b of the motor unit 13 and adjusts the rotational speed of the rotor 15. The control unit 19 also performs so-called single-axis control, actively controlling only one axis (axial direction) in the thrust direction with respect to the rotating shaft 12. The four radial axes (two axes perpendicular to the axial direction and the axes around each of those two axes) with respect to the rotating shaft 12 are passively controlled by the repulsive force between the fixed permanent magnet unit 20 and the rotating permanent magnet unit 30.

[0076] In the aforementioned single-axis control, the control unit 19 controls the magnitude and direction of the current applied to the support coil 17 based on the detection signal from the sensor 18, and adjusts the thrust support forces Fs1 and Fs2 acting on the rotating shaft 12 to hold the rotating shaft 12 in a predetermined support position as shown in Figure 1. The support position is a position in which the rotating shaft 12 is supported without contact with the housing 2 in the thrust and radial directions, respectively. The specific adjustment of the support forces Fs1 and Fs2 will be described below.

[0077] As the impeller 6 rotates with the rotating shaft 12, a negative pressure is created near the suction port 4a inside the housing 2, and this negative pressure draws the transfer fluid into the housing 2 from the suction port 4a. At this time, the negative pressure acts as an external force on the rotating shaft 12 in one direction in the thrust direction (towards the suction port 4a). This external force causes the rotating shaft 12 to shift from the support position shown in Figure 1 to one side in the thrust direction. The control unit 19 controls the magnitude and direction of the current applied to the support coil 17 based on the detection signal from the sensor 18, so that one axial end of the rotating shaft 12 does not come into contact with the housing 2 due to the external force, and applies a support force Fs1 to the rotating shaft 12 in the other direction in the thrust direction (see Figure 4).

[0078] When the rotating shaft 12 is in the support position, the first to third rotating permanent magnets 31 to 33 are slightly offset to the other side in the thrust direction relative to the first to fifth fixed permanent magnets 21 to 25. When the motor 10 is stopped from this state and current is no longer supplied to the support coil 17, the repulsive force between the fixed permanent magnet section 20 and the rotating permanent magnet section 30 acts on the rotating shaft 12, pushing it to the other side in the thrust direction. This pushing force causes the rotating shaft 12 to move from the support position to the other side in the thrust direction, and the second bulkhead 7b is held in place, pressed against the other end of the fourth bulkhead 7d in the thrust direction. As a result, when the motor 10 is stopped, the movement of the rotating shaft 12 to the other side in the thrust direction is restricted, thus preventing the impeller 6 from contacting and being damaged by the inner surface of the second housing 4.

[0079] As described above, when the motor 10 is driven from a state in which the rotating shaft 12 is held on the other side in the thrust direction, the control unit 19 controls the magnitude and direction of the current applied to the support coil 17 in order to return the rotating shaft 12 to the support position against the pushing force, thereby applying a support force Fs2 to the rotating shaft 12 on one side in the thrust direction (see Figure 7).

[0080] [Effects and Effects] According to the first embodiment, the rotation shaft 12 can be supported radially and non-contactually by the repulsive forces between the first to third fixed permanent magnets 21 to 23 and the first to third rotating permanent magnets 31 to 33, the repulsive force between the south pole of the fourth fixed permanent magnet 24 and the south pole of the first rotating permanent magnet 31, and the repulsive force between the north pole of the fifth fixed permanent magnet 25 and the north pole of the second rotating permanent magnet 32. This makes it possible to increase the radial support force Fr compared to the conventional case where the rotation shaft is supported only by the repulsive force between one set of fixed permanent magnets and one set of rotating permanent magnets. Therefore, even if the gap G between the fixed permanent magnet section 20 and the rotating permanent magnet section 30 becomes large, the radial support force Fr of the rotation shaft 12 can be secured.

[0081] Furthermore, the magnetic fluxes Ψc1 and Ψc2 generated by the support coil 17 are superimposed on the magnetic flux of one of the first fixed permanent magnet 21 and the second fixed permanent magnet 22 at each end of the rotation shaft 12 in the thrust direction, and are canceled out by the magnetic flux of the other, and are superimposed on the magnetic flux of one of the first rotating permanent magnet 31 and the second rotating permanent magnet 32, and are canceled out by the magnetic flux of the other. As a result, the magnetic flux density of the magnetic field is concentrated or concentrated at each end of the rotation shaft 12 in the thrust direction. Consequently, the magnetic fluxes Ψc1 and Ψc2 generated by the support coil 17 flow between the superimposed first fixed permanent magnet 21 and the second rotating permanent magnet 32 ​​(or between the superimposed second fixed permanent magnet 22 and the first rotating permanent magnet 31), thereby generating support forces Fs1 and Fs2 that support the rotation shaft 12 in the thrust direction.

[0082] Furthermore, when the magnetic fluxes Ψc1 and Ψc2 generated by the support coil 17 apply thrust-direction support forces Fs1 and Fs2 to the rotating shaft 12, loop-shaped magnetic fluxes Ψ20a and Ψ20b are generated in the fixed permanent magnet section 20 by the first to third fixed permanent magnets 21 to 23. In addition, loop-shaped magnetic fluxes Ψ30a and Ψ30b are generated in the rotating permanent magnet section 30 by the first to third rotating permanent magnets 31 to 33. The loop-shaped magnetic fluxes Ψ20a and Ψ20b can reduce leakage magnetic flux from the first fixed permanent magnet 21 and the second fixed permanent magnet 22. Furthermore, the loop-shaped magnetic fluxes Ψ30a and Ψ30b can reduce leakage magnetic flux from the first rotating permanent magnet 31 and the second rotating permanent magnet 32. This increases the magnetic flux density of Ψc1 and Ψc2 flowing through gap G, thereby increasing the thrust bearing forces Fs1 and Fs2.

[0083] In particular, in the magnetic levitation pump 1 of this embodiment, the gap G between the fixed permanent magnet section 20 and the rotating permanent magnet section 30 becomes larger in order to arrange the partition wall section 7 that separates the casing 11 side and the rotating shaft 12 side. For this reason, it becomes more effective to increase the thrust direction support forces Fs1 and Fs2 while securing the radial direction support force Fr as described above.

[0084] Furthermore, when the magnetic fluxes Ψc1 and Ψc2 generated by the support coil 17 apply thrust-direction support forces Fs1 and Fs2 to the rotating shaft 12, the fixed permanent magnet section 20 generates loop-shaped magnetic fluxes Ψ26a, Ψ26b, Ψ27a, and Ψ27b due to the fourth fixed permanent magnet 24 and the fifth fixed permanent magnet 25. As a result, the magnetic flux density of the magnetic fluxes Ψc1 and Ψc2 flowing through the gap G becomes even larger, further increasing the thrust-direction support forces Fs1 and Fs2.

[0085] <Second Embodiment> Figure 9 is an enlarged cross-sectional view of a part of the magnetic levitation motor 10 according to the second embodiment of the present invention. In the motor 10 of this embodiment, the magnetization directions of the first to fifth fixed permanent magnets 21 to 25 and the magnetization directions of the first to third rotating permanent magnets 31 to 33 differ from those of the first embodiment. The differences will be explained below.

[0086] [Fixed permanent magnet section] The first fixed permanent magnet 21 is magnetized radially such that the outer circumference in the radial direction is the south pole and the inner circumference in the radial direction is the north pole. The second fixed permanent magnet 22 is magnetized radially such that the outer circumference in the radial direction is the north pole and the inner circumference in the radial direction is the south pole. The third fixed permanent magnet 23A is magnetized thrust such that one side in the thrust direction is the north pole and the other side in the thrust direction is the south pole. The third fixed permanent magnet 23B is magnetized thrust such that one side in the thrust direction is the south pole and the other side in the thrust direction is the north pole.

[0087] The fourth fixed permanent magnet 24A is magnetized in the thrust direction such that one side in the thrust direction is the south pole and the other side in the thrust direction is the north pole. The fourth fixed permanent magnet 24B is magnetized in the thrust direction such that one side in the thrust direction is the north pole and the other side in the thrust direction is the south pole. The fifth fixed permanent magnet 25A is magnetized in the thrust direction such that one side in the thrust direction is the south pole and the other side in the thrust direction is the north pole. The fifth fixed permanent magnet 25B is magnetized in the thrust direction such that one side in the thrust direction is the north pole and the other side in the thrust direction is the south pole.

[0088] [Rotating permanent magnet section] The first rotating permanent magnet 31 is magnetized radially such that the outer circumference in the radial direction is the north pole and the inner circumference in the radial direction is the south pole. The second rotating permanent magnet 32 ​​is magnetized radially such that the outer circumference in the radial direction is the south pole and the inner circumference in the radial direction is the north pole. The third rotating permanent magnet 33A is magnetized thrustward such that one side in the thrust direction is the north pole and the other side in the thrust direction is the south pole. The third rotating permanent magnet 33B is magnetized thrustward such that one side in the thrust direction is the south pole and the other side in the thrust direction is the north pole.

[0089] With the above configuration, repulsive forces act between the first fixed permanent magnet 21 and the first rotating permanent magnet 31, between the second fixed permanent magnet 22 and the second rotating permanent magnet 32, and between the third fixed permanent magnet 23 and the third rotating permanent magnet 33. In addition, repulsive forces act between the north pole of the fourth fixed permanent magnet 24 and the north pole of the first rotating permanent magnet 31, and between the south pole of the fifth fixed permanent magnet 25 and the south pole of the second rotating permanent magnet 32. Due to these repulsive forces, an annular gap G is formed between the first to fifth fixed permanent magnets 21 to 25 and the first to third rotating permanent magnets 31 to 33 that are opposite each other. Then, these repulsive forces act on the rotating shaft 12 as a supporting force Fr that supports the rotating shaft 12 in the radial direction. As a result, the rotating shaft 12 is supported radially and non-contact with the casing 11 by the supporting force Fr.

[0090] [Support force on one side in the thrust direction] Figures 10 to 12 show the state in which current is applied to the support coil 17 in one direction in this embodiment. As shown in Figure 10, when a DC current is applied to the support coil 17 in the direction shown, a magnetic flux Ψc3 is generated by the support coil 17. The magnetic flux Ψc3 flows in a loop in the following order: magnetic cylinder portion 11a, second magnetic wall portion 11c, fixed permanent magnet portion 20 on the other side in the thrust direction, rotating permanent magnet portion 30 on the other side in the thrust direction, rotating shaft 12, rotating permanent magnet portion 30 on one side in the thrust direction, fixed permanent magnet portion 20 on one side in the thrust direction, first magnetic wall portion 11b, and magnetic cylinder portion 11a.

[0091] In this case, the magnetic flux Ψc3 is superimposed on the magnetic flux Ψ21b of the first fixed permanent magnet 21B on the other side in the thrust direction and canceled out by the magnetic flux Ψ22b of the second fixed permanent magnet 22B. As a result, the magnetic flux density of the magnetic field becomes dense at the first fixed permanent magnet 21B and sparse at the second fixed permanent magnet 22B. Furthermore, the magnetic flux Ψc3 is canceled out by the magnetic flux Ψ31b of the first rotating permanent magnet 31B on the other side in the thrust direction and superimposed on the magnetic flux Ψ32b of the second rotating permanent magnet 32B. As a result, the magnetic flux density of the magnetic field becomes sparse at the first rotating permanent magnet 31B and dense at the second rotating permanent magnet 32B.

[0092] On the other hand, the magnetic flux Ψc3 is superimposed on the magnetic flux Ψ31a of the first rotating permanent magnet 31A on one side in the thrust direction and canceled out by the magnetic flux Ψ32a of the second rotating permanent magnet 32A. As a result, the magnetic flux density of the magnetic field becomes dense at the first rotating permanent magnet 31A and sparse at the second rotating permanent magnet 32A. Furthermore, the magnetic flux Ψc3 is canceled out by the magnetic flux Ψ21a of the first fixed permanent magnet 21A on one side in the thrust direction and superimposed on the magnetic flux Ψ22a of the second fixed permanent magnet 22A. As a result, the magnetic flux density of the magnetic field becomes sparse at the first fixed permanent magnet 21A and dense at the second fixed permanent magnet 22A.

[0093] As described above, due to the occurrence of density variations in the magnetic flux density of the magnetic field on both the other and one side of the thrust direction, most of the magnetic flux Ψc3 flows as shown in Figure 11. That is, most of the magnetic flux Ψc3 on the other side of the thrust direction flows from the first fixed permanent magnet 21B toward the second rotating permanent magnet 32B. Also, most of the magnetic flux Ψc3 on the one side of the thrust direction flows from the first rotating permanent magnet 31A toward the second fixed permanent magnet 22A. As a result, at the second rotating permanent magnet 32B and the first rotating permanent magnet 31A, the magnetic flux lines of the magnetic flux Ψc3 are inclined from their respective outer surfaces toward the other side of the gap G in the thrust direction, so a supporting force Fs1 acts on the rotation axis 12 toward the other side of the thrust direction toward which the magnetic flux lines are directed.

[0094] In this embodiment as well, the support force Fs1 can be increased by the first to fifth fixed permanent magnets 21 to 25 and the first to third rotating permanent magnets 31 to 33. The reason for this will be explained using Figure 12. As shown in Figure 12, on one side in the thrust direction, the magnetic fluxes Ψ21a to Ψ23a of the first to third fixed permanent magnets 21A to 23A generate a loop-shaped magnetic flux Ψ20a that flows counterclockwise in the figure, spanning the inner circumference of these fixed permanent magnets 21A to 23A and the outer circumference of the gap G. Also on one side in the thrust direction, the magnetic fluxes Ψ31a to Ψ33a of the first to third rotating permanent magnets 31A to 33A generate a loop-shaped magnetic flux Ψ30a that flows clockwise in the figure, spanning the outer circumference of these rotating permanent magnets 31A to 33A and the inner circumference of the gap G. Furthermore, on one side in the thrust direction, the magnetic fluxes Ψ22a and Ψ25a of the second and fifth fixed permanent magnets 22A and 25A generate a loop-shaped magnetic flux Ψ27a that flows in a clockwise direction in the figure, spanning the inner circumference of these fixed permanent magnets 22A and 25A and the outer circumference of the gap G.

[0095] The generation of a loop-shaped magnetic flux Ψ20a reduces the leakage magnetic flux from the first fixed permanent magnet 21A and the second fixed permanent magnet 22A. Furthermore, the generation of a loop-shaped magnetic flux Ψ30a reduces the leakage magnetic flux from the first rotating permanent magnet 31A and the second rotating permanent magnet 32A. Additionally, the generation of a loop-shaped magnetic flux Ψ27a facilitates the flow of magnetic flux Ψc3 between two adjacent loop-shaped magnetic fluxes Ψ20a and Ψ27a in the thrust direction. As a result, the magnetic flux density of the magnetic flux Ψc3 flowing through the gap G on one side of the thrust direction increases, thereby increasing the support force Fs1.

[0096] On the other side of the thrust direction, the magnetic fluxes Ψ21b to Ψ23b of the first to third fixed permanent magnets 21B to 23B generate a loop-shaped magnetic flux Ψ20b that flows clockwise in the figure, spanning the inner circumference of these fixed permanent magnets 21B to 23B and the outer circumference of the gap G. Also on the other side of the thrust direction, the magnetic fluxes Ψ31b to Ψ33b of the first to third rotating permanent magnets 31B to 33B generate a loop-shaped magnetic flux Ψ30b that flows counterclockwise in the figure, spanning the outer circumference of these rotating permanent magnets 31B to 33B and the inner circumference of the gap G. Furthermore, on the other side in the thrust direction, the magnetic fluxes Ψ21b and Ψ24b of the first and fourth fixed permanent magnets 21B and 24B generate a loop-shaped magnetic flux Ψ26b that flows in a clockwise direction in the figure, spanning the inner circumference of these fixed permanent magnets 21B and 24B and the outer circumference of the gap G.

[0097] The generation of a loop-shaped magnetic flux Ψ20b reduces the leakage magnetic flux from the first fixed permanent magnet 21B and the second fixed permanent magnet 22B. Furthermore, the generation of a loop-shaped magnetic flux Ψ30b reduces the leakage magnetic flux from the first rotating permanent magnet 31B and the second rotating permanent magnet 32B. Additionally, the generation of a loop-shaped magnetic flux Ψ26b makes it easier for magnetic flux Ψc3 to flow between the two adjacent loop-shaped magnetic fluxes Ψ20b and Ψ26b in the thrust direction. As a result, the magnetic flux density of the magnetic flux Ψc3 flowing through the gap G on the other side of the thrust direction also increases, further increasing the support force Fs1.

[0098] [Support force on the other side in the thrust direction] Figures 13 to 15 show the state in which current is applied to the support coil 17 in opposite directions in this embodiment. As shown in Figure 13, when a DC current is applied to the support coil 17 in the direction shown, a magnetic flux Ψc4 is generated by the support coil 17. The magnetic flux Ψc4 flows in a loop in the following order: magnetic cylinder portion 11a, first magnetic wall portion 11b, fixed permanent magnet portion 20 on one side in the thrust direction, rotating permanent magnet portion 30 on one side in the thrust direction, rotating shaft 12, rotating permanent magnet portion 30 on the other side in the thrust direction, fixed permanent magnet portion 20 on the other side in the thrust direction, second magnetic wall portion 11c, and magnetic cylinder portion 11a.

[0099] In this case, the magnetic flux Ψc4 is superimposed on the magnetic flux Ψ21a of the first fixed permanent magnet 21A on one side in the thrust direction and canceled out by the magnetic flux Ψ22a of the second fixed permanent magnet 22A. As a result, the magnetic flux density of the magnetic field becomes denser at the first fixed permanent magnet 21A and sparser at the second fixed permanent magnet 22A. Furthermore, the magnetic flux Ψc4 is canceled out by the magnetic flux Ψ31a of the first rotating permanent magnet 31A on one side in the thrust direction and superimposed on the magnetic flux Ψ32a of the second rotating permanent magnet 32A. As a result, the magnetic flux density of the magnetic field becomes sparser at the first rotating permanent magnet 31A and denser at the second rotating permanent magnet 32A.

[0100] On the other hand, the magnetic flux Ψc4 is superimposed by the magnetic flux Ψ31b of the first rotating permanent magnet 31B on the other side in the thrust direction, and canceled out by the magnetic flux Ψ32b of the second rotating permanent magnet 32B. As a result, the magnetic flux density of the magnetic field becomes dense at the first rotating permanent magnet 31B and sparse at the second rotating permanent magnet 32B. Furthermore, the magnetic flux Ψc4 is canceled out by the magnetic flux Ψ21b of the first fixed permanent magnet 21B on the other side in the thrust direction, and superimposed on the magnetic flux Ψ22b of the second fixed permanent magnet 22B. As a result, the magnetic flux density of the magnetic field becomes sparse at the first fixed permanent magnet 21B and dense at the second fixed permanent magnet 22B.

[0101] As described above, due to the occurrence of density variations in the magnetic flux density on both sides of the thrust direction, most of the magnetic flux Ψc4 flows as shown in Figure 14. Specifically, most of the magnetic flux Ψc4 on one side of the thrust direction flows from the first fixed permanent magnet 21A towards the second rotating permanent magnet 32A. Also, most of the magnetic flux Ψc4 on the other side of the thrust direction flows from the first rotating permanent magnet 31B towards the second fixed permanent magnet 22B. As a result, at the second rotating permanent magnet 32A and the first rotating permanent magnet 31B, the magnetic flux lines of Ψc4 are inclined from their respective outer surfaces toward one side of the gap G in the thrust direction, so a supporting force Fs2 acts on the rotation axis 12 toward the other side of the thrust direction toward which the magnetic flux lines are directed.

[0102] In this embodiment as well, the support force Fs2 can be increased by the first to fifth fixed permanent magnets 21 to 25 and the first to third rotating permanent magnets 31 to 33. The reason for this will be explained using Figure 15. As shown in Figure 15, on one side in the thrust direction, loop-shaped magnetic flux Ψ20a and loop-shaped magnetic flux Ψ30a are generated, similar to the case shown in Figure 12. The generation of loop-shaped magnetic fluxes Ψ20a and Ψ30a reduces the leakage magnetic flux from the first and second fixed permanent magnets 21A and 22A, and the leakage magnetic flux from the first and second rotating permanent magnets 31A and 32A.

[0103] Furthermore, on one side in the thrust direction, the magnetic fluxes Ψ21a and Ψ24a of the first and fourth fixed permanent magnets 21A and 24A generate a loop-shaped magnetic flux Ψ26a that flows clockwise in the figure, spanning the inner circumference of these fixed permanent magnets 21A and 24A and the outer circumference of the gap G. The generation of the loop-shaped magnetic flux Ψ26a makes it easier for the magnetic flux Ψc4 to flow between two adjacent loop-shaped magnetic fluxes Ψ26a and Ψ20a in the thrust direction. As a result, the magnetic flux density of the magnetic flux Ψc4 flowing through the gap G on one side in the thrust direction increases, thereby increasing the support force Fs2.

[0104] On the other side of the thrust direction, loop-shaped magnetic fluxes Ψ20b and Ψ30b are generated, similar to the case shown in Figure 12. The generation of loop-shaped magnetic fluxes Ψ20b and Ψ30b reduces the leakage flux from the first and second fixed permanent magnets 21B and 22B, and the leakage flux from the first and second rotating permanent magnets 31B and 32B.

[0105] Furthermore, on the other side in the thrust direction, the magnetic fluxes Ψ22b and Ψ25b of the second and fifth fixed permanent magnets 22B and 25B generate a loop-shaped magnetic flux Ψ27b that flows counterclockwise in the figure, spanning the inner circumference of these fixed permanent magnets 22B and 25B and the outer circumference of the gap G. The generation of the loop-shaped magnetic flux Ψ27b makes it easier for the magnetic flux Ψc4 to flow between the two adjacent loop-shaped magnetic fluxes Ψ27b and Ψ20b in the thrust direction. As a result, the magnetic flux density of the magnetic flux Ψc4 flowing through the gap G on the other side in the thrust direction also increases, so the support force Fs2 can be further increased.

[0106] Other components of this embodiment are the same as those of the first embodiment, and therefore are denoted by the same reference numerals, and their descriptions are omitted. Thus, the pump 1 and electric motor 10 of this embodiment also provide the same effects and advantages as those of the first embodiment.

[0107] <Third Embodiment> Figure 16 is an enlarged cross-sectional view of a part of the magnetic levitation motor 10 according to the third embodiment of the present invention. This embodiment is a modification of the first embodiment. In the motor 10 of this embodiment, the configuration of the rotating permanent magnet section 30 differs from that of the first embodiment. The differences will be described below.

[0108] [Rotating permanent magnet section] The rotating permanent magnet section 30 of this embodiment includes a fourth rotating permanent magnet 34 and a fifth rotating permanent magnet 35, in addition to the first to third rotating permanent magnets 31 to 33. Each of the rotating permanent magnets 31 to 35 is formed in an annular shape. The radial thickness of each of the rotating permanent magnets 31 to 35 is the same.

[0109] The first rotating permanent magnets 31 are arranged in pairs so as to face each of the pair of first fixed permanent magnets 21. The length of the first rotating permanent magnets 31 in the thrust direction is not particularly limited, but in this embodiment it is the same as the length of the first fixed permanent magnets 21 in the thrust direction. The second rotating permanent magnets 32 are arranged in pairs so as to face each of the pair of second fixed permanent magnets 22. The length of the second rotating permanent magnets 32 in the thrust direction is not particularly limited, but in this embodiment it is the same as the length of the second fixed permanent magnets 22 in the thrust direction.

[0110] The fourth rotating permanent magnet 34 is arranged in pairs so as to face each of the pair of fourth fixed permanent magnets 24. Each pair of fourth rotating permanent magnets 34 consists of a fourth rotating permanent magnet 34A positioned opposite the fourth fixed permanent magnet 24A, and a fourth rotating permanent magnet 34B positioned opposite the fourth fixed permanent magnet 24B.

[0111] The fourth rotating permanent magnets 34A and 34B are magnetized in opposite directions in the thrust direction. Furthermore, the fourth rotating permanent magnet 34A is magnetized in the same direction as the opposing fourth fixed permanent magnet 24A. Similarly, the fourth rotating permanent magnet 34B is magnetized in the same direction as the opposing fourth fixed permanent magnet 24B. In this embodiment, the fourth rotating permanent magnet 34A is magnetized such that one side in the thrust direction is the north pole and the other side is the south pole. The fourth rotating permanent magnet 34B is magnetized such that one side in the thrust direction is the south pole and the other side is the north pole. The length of the fourth rotating permanent magnet 34 in the thrust direction is not particularly limited, but in this embodiment it is the same as the length of the fourth fixed permanent magnet 24 in the thrust direction.

[0112] The fifth rotating permanent magnet 35 is arranged in pairs so as to face each of the pair of fifth fixed permanent magnets 25. Each pair of fifth rotating permanent magnets 35 consists of a fifth rotating permanent magnet 35A positioned opposite the fifth fixed permanent magnet 25A, and a fifth rotating permanent magnet 35B positioned opposite the fifth fixed permanent magnet 25B.

[0113] The fifth rotating permanent magnets 35A and 35B are magnetized in opposite directions in the thrust direction. Furthermore, the fifth rotating permanent magnet 35A is magnetized in the same direction as the opposing fifth fixed permanent magnet 25A. Similarly, the fifth rotating permanent magnet 35B is magnetized in the same direction as the opposing fifth fixed permanent magnet 25B. In this embodiment, the fifth rotating permanent magnet 35A is magnetized such that one side in the thrust direction is the north pole and the other side is the south pole. The fifth rotating permanent magnet 35B is magnetized such that one side in the thrust direction is the south pole and the other side is the north pole. The length of the fifth rotating permanent magnet 35 in the thrust direction is not particularly limited, but in this embodiment it is the same as the length of the fifth fixed permanent magnet 25 in the thrust direction.

[0114] With the above configuration, repulsive forces act between the first fixed permanent magnet 21 and the first rotating permanent magnet 31, between the second fixed permanent magnet 22 and the second rotating permanent magnet 32, between the third fixed permanent magnet 23 and the third rotating permanent magnet 33, between the fourth fixed permanent magnet 24 and the fourth rotating permanent magnet 34, and between the fifth fixed permanent magnet 25 and the fifth rotating permanent magnet 35. Due to these repulsive forces, an annular gap G is formed between the first to fifth fixed permanent magnets 21 to 25 and the first to fifth rotating permanent magnets 31 to 35 that are opposite to each other. Then, these repulsive forces act on the rotating shaft 12 as a supporting force Fr that supports the rotating shaft 12 in the radial direction. As a result, the rotating shaft 12 is supported radially and non-contact with the casing 11 by a larger supporting force Fr than in the first embodiment (see Figure 3).

[0115] [Support force on one side in the thrust direction] Figure 17 shows the state in which a current is applied to the support coil 17 in one direction in this embodiment. As shown in Figure 17, when a DC current is applied to the support coil 17 in the direction shown, a magnetic flux Ψc5 is generated by the support coil 17. The magnetic flux Ψc5 flows in a loop, similar to the magnetic flux Ψc1 in the first embodiment (see Figure 3), causing a concentration of density in the magnetic field on both the one and the other side in the thrust direction.

[0116] As a result, most of the magnetic flux Ψc5 flows as shown in Figure 17. That is, most of the magnetic flux Ψc5 on one side in the thrust direction flows from the second fixed permanent magnet 22A toward the first rotating permanent magnet 31A. Also, most of the magnetic flux Ψc5 on the other side in the thrust direction flows from the second rotating permanent magnet 32B toward the first fixed permanent magnet 21B. Consequently, at the first rotating permanent magnet 31A and the second rotating permanent magnet 32B, the magnetic flux lines of Ψc5 are inclined from their respective outer surfaces toward the other side in the thrust direction of the gap G, so a supporting force Fs1 acts on the rotation axis 12 toward the other side in the thrust direction toward which the magnetic flux lines are directed.

[0117] In this embodiment as well, the support force Fs1 can be increased by the first to fifth fixed permanent magnets 21 to 25 and the first to fifth rotating permanent magnets 31 to 35. The reason for this is explained below. On one side in the thrust direction, loop-shaped magnetic flux Ψ20a and loop-shaped magnetic flux Ψ30a are generated, similar to the first embodiment (see Figure 5). The generation of loop-shaped magnetic fluxes Ψ20a and Ψ30a reduces the leakage magnetic flux from the first and second fixed permanent magnets 21A and 22A, and the leakage magnetic flux from the first and second rotating permanent magnets 31A and 32A.

[0118] Furthermore, on one side in the thrust direction, similar to the first embodiment (see Figure 5), a loop-shaped magnetic flux Ψ27a is generated that flows counterclockwise in the figure, spanning the inner circumference of the fixed permanent magnets 22A and 25A and the outer circumference of the gap G. The generation of the loop-shaped magnetic flux Ψ27a makes it easier for the magnetic flux Ψc5 to flow between two adjacent loop-shaped magnetic fluxes Ψ20a and Ψ27a in the thrust direction. In addition, the magnetic fluxes Ψ31a and Ψ34a of the first and fourth rotating permanent magnets 31A and 34A generate a loop-shaped magnetic flux Ψ36a that flows clockwise in the figure, spanning the outer circumference of these rotating permanent magnets 31A and 34A and the inner circumference of the gap G. The generation of the loop-shaped magnetic flux Ψ36a makes it easier for the magnetic flux Ψc5 to flow between two adjacent loop-shaped magnetic fluxes Ψ36a and Ψ30a in the thrust direction. As a result, the magnetic flux density of the magnetic flux Ψc5 flowing through the gap G on one side in the thrust direction increases, which allows the support force Fs1 to be increased.

[0119] On the other side in the thrust direction, loop-shaped magnetic fluxes Ψ20b and Ψ30b are generated, similar to the first embodiment (see Figure 5). The generation of loop-shaped magnetic fluxes Ψ20b and Ψ30b reduces the leakage flux from the first and second fixed permanent magnets 21B and 22B, and the leakage flux from the first and second rotating permanent magnets 31B and 32B.

[0120] Furthermore, on the other side in the thrust direction, similar to the first embodiment (see Figure 5), a loop-shaped magnetic flux Ψ26b is generated that flows clockwise in the figure, spanning the inner circumference of the fixed permanent magnets 21B and 24B and the outer circumference of the gap G. The generation of the loop-shaped magnetic flux Ψ26b makes it easier for the magnetic flux Ψc5 to flow between two adjacent loop-shaped magnetic fluxes Ψ20b and Ψ26b in the thrust direction. In addition, the magnetic fluxes Ψ32b and Ψ35b of the second and fifth rotating permanent magnets 32B and 35B generate a loop-shaped magnetic flux Ψ37b that flows counterclockwise in the figure, spanning the outer circumference of these rotating permanent magnets 32B and 35B and the inner circumference of the gap G. The generation of the loop-shaped magnetic flux Ψ37b makes it easier for the magnetic flux Ψc5 to flow between two adjacent loop-shaped magnetic fluxes Ψ37b and Ψ30b in the thrust direction. As a result, the magnetic flux density of the magnetic flux Ψc5 flowing through the gap G on the other side in the thrust direction also increases, allowing the support force Fs1 to be further increased.

[0121] [Support force on the other side in the thrust direction] Figure 18 shows the state in which current is applied to the support coil 17 in the opposite direction in this embodiment. As shown in Figure 18, when a DC current is applied to the support coil 17 in the direction shown, a magnetic flux Ψc6 is generated by the support coil 17. The magnetic flux Ψc6 flows in a loop, similar to the magnetic flux Ψc2 in the first embodiment (see Figure 6), causing unevenness in the magnetic flux density of the magnetic field on both the one side and the other side in the thrust direction.

[0122] As a result, most of the magnetic flux Ψc6 flows as shown in Figure 18. That is, most of the magnetic flux Ψc6 on the other side in the thrust direction flows from the second fixed permanent magnet 22B towards the first rotating permanent magnet 31B. Also, most of the magnetic flux Ψc6 on one side in the thrust direction flows from the second rotating permanent magnet 32A towards the first fixed permanent magnet 21A. Consequently, at the first rotating permanent magnet 31B and the second rotating permanent magnet 32A, the magnetic flux lines of Ψc6 are inclined from their respective outer surfaces toward one side in the thrust direction of the gap G, so a support force Fs2 acts on the rotation axis 12 toward the thrust direction toward which the magnetic flux lines are directed.

[0123] In this embodiment as well, the support force Fs2 can be increased by the first to fifth fixed permanent magnets 21 to 25 and the first to fifth rotating permanent magnets 31 to 35. The reason for this is explained below. On one side in the thrust direction, loop-shaped magnetic flux Ψ20a and loop-shaped magnetic flux Ψ30a are generated, similar to the case shown in Figure 17. The generation of loop-shaped magnetic fluxes Ψ20a and Ψ30a reduces the leakage magnetic flux from the first and second fixed permanent magnets 21A and 22A, and the leakage magnetic flux from the first and second rotating permanent magnets 31A and 32A.

[0124] Furthermore, on one side in the thrust direction, similar to the first embodiment (see Figure 8), a loop-shaped magnetic flux Ψ26a is generated that flows counterclockwise in the figure, spanning the inner circumference of the fixed permanent magnets 21A and 24A and the outer circumference of the gap G. The generation of the loop-shaped magnetic flux Ψ26a makes it easier for the magnetic flux Ψc6 to flow between two adjacent loop-shaped magnetic fluxes Ψ26a and Ψ20a in the thrust direction. In addition, the magnetic fluxes Ψ32a and Ψ35a of the second and fifth rotating permanent magnets 32A and 35A generate a loop-shaped magnetic flux Ψ37a that flows clockwise in the figure, spanning the outer circumference of these rotating permanent magnets 32A and 35A and the inner circumference of the gap G. The generation of the loop-shaped magnetic flux Ψ37a makes it easier for the magnetic flux Ψc6 to flow between two adjacent loop-shaped magnetic fluxes Ψ30a and Ψ37a in the thrust direction. As a result, the magnetic flux density of the magnetic flux Ψc6 flowing through the gap G on one side in the thrust direction increases, thereby increasing the support force Fs2.

[0125] On the other side of the thrust direction, loop-shaped magnetic fluxes Ψ20b and Ψ30b are generated, similar to the case shown in Figure 17. The generation of loop-shaped magnetic fluxes Ψ20b and Ψ30b reduces the leakage flux from the first and second fixed permanent magnets 21B and 22B, and the leakage flux from the first and second rotating permanent magnets 31B and 32B.

[0126] Furthermore, on the other side in the thrust direction, similar to the first embodiment (see Figure 8), a loop-shaped magnetic flux Ψ27b is generated that flows clockwise in the figure, spanning the inner circumference of the fixed permanent magnets 22B and 25B and the outer circumference of the gap G. The generation of the loop-shaped magnetic flux Ψ27b makes it easier for the magnetic flux Ψc6 to flow between two adjacent loop-shaped magnetic fluxes Ψ27b and Ψ20b in the thrust direction. In addition, the magnetic fluxes Ψ31b and Ψ34b of the first and fourth rotating permanent magnets 31B and 34B generate a loop-shaped magnetic flux Ψ36b that flows counterclockwise in the figure, spanning the outer circumference of these rotating permanent magnets 31B and 34B and the inner circumference of the gap G. The generation of the loop-shaped magnetic flux Ψ36b makes it easier for the magnetic flux Ψc6 to flow between two adjacent loop-shaped magnetic fluxes Ψ30b and Ψ36b in the thrust direction. As a result, the magnetic flux density of the magnetic flux Ψc6 flowing through the gap G on the other side in the thrust direction also increases, so the support force Fs2 can be further increased. The other components of this embodiment are the same as those of the first embodiment, so they are denoted by the same reference numerals and their descriptions are omitted.

[0127] [Effects and Effects] According to the third embodiment, the repulsive forces between the first to third fixed permanent magnets 21 to 23 and the first to third rotating permanent magnets 31 to 33, the repulsive force between the fourth fixed permanent magnet 24 and the fourth rotating permanent magnet 34, and the repulsive force between the fifth fixed permanent magnet 25 and the fifth rotating permanent magnet 35 act together, so the radial support force Fr can be further increased. Therefore, even if the gap G between the fixed permanent magnet section 20 and the rotating permanent magnet section 30 becomes even larger, the radial support force Fr of the rotating shaft 12 can be secured.

[0128] Furthermore, the magnetic fluxes Ψc5 and Ψc6 generated by the support coil 17 are superimposed on the magnetic flux of one of the first fixed permanent magnet 21 and the second fixed permanent magnet 22 at each end of the rotation shaft 12 in the thrust direction, and are canceled out by the magnetic flux of the other, and are superimposed on the magnetic flux of one of the first rotating permanent magnet 31 and the second rotating permanent magnet 32, and are canceled out by the magnetic flux of the other. As a result, the magnetic flux density of the magnetic field is concentrated or concentrated at each end of the rotation shaft 12 in the thrust direction. Consequently, the magnetic fluxes Ψc5 and Ψc6 generated by the support coil 17 flow between the superimposed first fixed permanent magnet 21 and the second rotating permanent magnet 32 ​​(or between the superimposed second fixed permanent magnet 22 and the first rotating permanent magnet 31), thereby generating support forces Fs1 and Fs2 that support the rotation shaft 12 in the thrust direction.

[0129] Furthermore, when the magnetic fluxes Ψc5 and Ψc6 generated by the support coil 17 apply thrust-direction support forces Fs1 and Fs2 to the rotating shaft 12, loop-shaped magnetic fluxes Ψ20a and Ψ20b are generated in the fixed permanent magnet section 20 by the first to third fixed permanent magnets 21 to 23. In addition, loop-shaped magnetic fluxes Ψ30a and Ψ30b are generated in the rotating permanent magnet section 30 by the first to third rotating permanent magnets 31 to 33. The loop-shaped magnetic fluxes Ψ20a and Ψ20b can reduce the leakage magnetic flux from the first fixed permanent magnet 21 and the second fixed permanent magnet 22. Furthermore, the loop-shaped magnetic fluxes Ψ30a and Ψ30b can reduce the leakage magnetic flux from the first rotating permanent magnet 31 and the second rotating permanent magnet 32. This increases the magnetic flux density of Ψc5 and Ψc26 flowing through gap G, thereby increasing the thrust bearing forces Fs1 and Fs2.

[0130] Furthermore, when the magnetic fluxes Ψc5 and Ψc6 generated by the support coil 17 apply thrust-direction support forces Fs1 and Fs2 to the rotating shaft 12, the fixed permanent magnet section 20 generates loop-shaped magnetic fluxes Ψ27a, Ψ27b, Ψ26a, and Ψ26b due to the fourth fixed permanent magnet 24 and the fifth fixed permanent magnet 25. In addition, the rotating permanent magnet section 30 generates loop-shaped magnetic fluxes Ψ36a, Ψ36b, Ψ37a, and Ψ37b due to the fourth rotating permanent magnet 34 and the fifth rotating permanent magnet 35. As a result, the magnetic flux density of the magnetic fluxes Ψc5 and Ψc6 flowing through the gap G becomes even larger, and the thrust-direction support forces Fs1 and Fs2 can be further increased.

[0131] <Fourth Embodiment> Figure 19 is an enlarged cross-sectional view of a part of the magnetic levitation motor 10 according to the fourth embodiment of the present invention. This embodiment is a modification of the third embodiment. In the motor 10 of this embodiment, the magnetization directions of the first to fifth fixed permanent magnets 21 to 25 and the magnetization directions of the first to fifth rotating permanent magnets 31 to 35 differ from those of the third embodiment. The differences will be explained below.

[0132] The magnetization directions of the first to fifth fixed permanent magnets 21 to 25, and the magnetization directions of the first to third rotating permanent magnets 31 to 33 are the same as in the second embodiment (see Figure 9), so their description is omitted. The fourth rotating permanent magnet 34A is magnetized in the thrust direction such that one side in the thrust direction is the south pole and the other side in the thrust direction is the north pole. The fourth rotating permanent magnet 34B is magnetized in the thrust direction such that one side in the thrust direction is the north pole and the other side in the thrust direction is the south pole. The fifth rotating permanent magnet 35A is magnetized in the thrust direction such that one side in the thrust direction is the south pole and the other side in the thrust direction is the north pole. The fifth rotating permanent magnet 35B is magnetized in the thrust direction such that one side in the thrust direction is the north pole and the other side in the thrust direction is the south pole.

[0133] With the above configuration, repulsive forces act between the first fixed permanent magnet 21 and the first rotating permanent magnet 31, between the second fixed permanent magnet 22 and the second rotating permanent magnet 32, between the third fixed permanent magnet 23 and the third rotating permanent magnet 33, between the fourth fixed permanent magnet 24 and the fourth rotating permanent magnet 34, and between the fifth fixed permanent magnet 25 and the fifth rotating permanent magnet 35. Due to these repulsive forces, an annular gap G is formed between the first to fifth fixed permanent magnets 21 to 25 and the first to fifth rotating permanent magnets 31 to 35 that are opposite to each other. Then, these repulsive forces act on the rotating shaft 12 as a supporting force Fr that supports the rotating shaft 12 in the radial direction. As a result, the rotating shaft 12 is supported radially and non-contact with the casing 11 by a larger supporting force Fr than in the second embodiment (see Figure 9).

[0134] [Support force on one side in the thrust direction] Figure 20 shows the state in which a current is applied to the support coil 17 in one direction in this embodiment. As shown in Figure 20, when a DC current is applied to the support coil 17 in the direction shown, a magnetic flux Ψc7 is generated by the support coil 17. The magnetic flux Ψc7 flows in a loop, similar to the magnetic flux Ψc3 in the second embodiment (see Figure 10), causing a concentration of density in the magnetic flux density of the magnetic field on both the one side and the other side in the thrust direction.

[0135] As a result, most of the magnetic flux Ψc7 flows as shown in Figure 20. That is, most of the magnetic flux Ψc7 on the other side in the thrust direction flows from the first fixed permanent magnet 21B towards the second rotating permanent magnet 32B. Also, most of the magnetic flux Ψc7 on one side in the thrust direction flows from the first rotating permanent magnet 31A towards the second fixed permanent magnet 22A. Consequently, at the second rotating permanent magnet 32B and the first rotating permanent magnet 31A, the magnetic flux lines of Ψc7 are inclined from their respective outer surfaces toward the other side in the thrust direction of the gap G, so a supporting force Fs1 acts on the rotation axis 12 toward the other side in the thrust direction toward which the magnetic flux lines are directed.

[0136] In this embodiment as well, the support force Fs1 can be increased by the first to fifth fixed permanent magnets 21 to 25 and the first to fifth rotating permanent magnets 31 to 35. The reason for this is explained below. On one side in the thrust direction, loop-shaped magnetic flux Ψ20a and loop-shaped magnetic flux Ψ30b are generated, similar to the second embodiment (see Figure 12). The generation of loop-shaped magnetic fluxes Ψ20a and Ψ30a reduces the leakage magnetic flux from the first and second fixed permanent magnets 21A and 22A, and the leakage magnetic flux from the first and second rotating permanent magnets 31A and 32A.

[0137] Furthermore, on one side in the thrust direction, similar to the second embodiment (see Figure 12), a loop-shaped magnetic flux Ψ27a is generated that flows clockwise in the figure, spanning the inner circumference of the fixed permanent magnets 22A and 25A and the outer circumference of the gap G. The generation of the loop-shaped magnetic flux Ψ27a makes it easier for the magnetic flux Ψc7 to flow between two adjacent loop-shaped magnetic fluxes Ψ20a and Ψ27a in the thrust direction. In addition, the magnetic fluxes Ψ31a and Ψ34a of the first and fourth rotating permanent magnets 31A and 34A generate a loop-shaped magnetic flux Ψ36a that flows counterclockwise in the figure, spanning the outer circumference of these rotating permanent magnets 31A and 34A and the inner circumference of the gap G. The generation of the loop-shaped magnetic flux Ψ36a makes it easier for the magnetic flux Ψc7 to flow between two adjacent loop-shaped magnetic fluxes Ψ36a and Ψ30a in the thrust direction. As a result, the magnetic flux density Ψc7 flowing through the gap G on one side in the thrust direction increases, thereby increasing the support force Fs1.

[0138] On the other side of the thrust direction, loop-shaped magnetic fluxes Ψ20a and Ψ30b are generated, similar to the second embodiment (see Figure 12). The generation of loop-shaped magnetic fluxes Ψ20b and Ψ30b reduces the leakage flux from the first and second fixed permanent magnets 21B and 22B, and the leakage flux from the first and second rotating permanent magnets 31B and 32B.

[0139] Furthermore, on the other side in the thrust direction, similar to the second embodiment (see Figure 12), a loop-shaped magnetic flux Ψ26b is generated that flows counterclockwise in the figure, spanning the inner circumference of the fixed permanent magnets 21B and 24B and the outer circumference of the gap G. The generation of the loop-shaped magnetic flux Ψ26b makes it easier for the magnetic flux Ψc7 to flow between two adjacent loop-shaped magnetic fluxes Ψ20b and Ψ26b in the thrust direction. In addition, the magnetic fluxes Ψ32b and Ψ35b of the second and fifth rotating permanent magnets 32B and 35B generate a loop-shaped magnetic flux Ψ37b that flows clockwise in the figure, spanning the outer circumference of these rotating permanent magnets 32B and 35B and the inner circumference of the gap G. The generation of the loop-shaped magnetic flux Ψ37b makes it easier for the magnetic flux Ψc7 to flow between two adjacent loop-shaped magnetic fluxes Ψ37b and Ψ30b in the thrust direction. As a result, the magnetic flux density of the magnetic flux Ψc7 flowing through the gap G on the other side in the thrust direction also increases, allowing the support force Fs1 to be further increased.

[0140] [Support force on the other side in the thrust direction] Figure 21 shows the state in which current is applied to the support coil 17 in the opposite direction in this embodiment. As shown in Figure 21, when a DC current is applied to the support coil 17 in the direction shown, a magnetic flux Ψc8 is generated by the support coil 17. The magnetic flux Ψc8 flows in a loop, similar to the magnetic flux Ψc4 in the second embodiment (see Figure 13), causing a concentration of density in the magnetic flux density of the magnetic field on both the one side and the other side in the thrust direction.

[0141] As a result, most of the magnetic flux Ψc8 flows as shown in Figure 21. That is, most of the magnetic flux Ψc8 on one side in the thrust direction flows from the first fixed permanent magnet 21A towards the second rotating permanent magnet 32A. Also, most of the magnetic flux Ψc8 on the other side in the thrust direction flows from the first rotating permanent magnet 31B towards the second fixed permanent magnet 22B. Consequently, at the second rotating permanent magnet 32A and the first rotating permanent magnet 31B, the magnetic flux lines of Ψc8 are inclined from their respective outer surfaces toward one side in the thrust direction of the gap G, so a supporting force Fs2 acts on the rotation axis 12 toward the thrust direction toward which the magnetic flux lines are pointing.

[0142] In this embodiment as well, the support force Fs2 can be increased by the first to fifth fixed permanent magnets 21 to 25 and the first to fifth rotating permanent magnets 31 to 35. The reason for this is explained below. On one side in the thrust direction, loop-shaped magnetic flux Ψ20a and loop-shaped magnetic flux Ψ30b are generated, similar to the case shown in Figure 20. The generation of loop-shaped magnetic fluxes Ψ20a and Ψ30a reduces the leakage magnetic flux from the first and second fixed permanent magnets 21A and 22A, and the leakage magnetic flux from the first and second rotating permanent magnets 31A and 32A.

[0143] Furthermore, on one side in the thrust direction, similar to the second embodiment (see Figure 15), a loop-shaped magnetic flux Ψ26a is generated that flows clockwise in the figure, spanning the inner circumference of the fixed permanent magnets 21A and 24A and the outer circumference of the gap G. The generation of the loop-shaped magnetic flux Ψ26a makes it easier for the magnetic flux Ψc8 to flow between two adjacent loop-shaped magnetic fluxes Ψ26a and Ψ20a in the thrust direction. In addition, the magnetic fluxes Ψ32a and Ψ35a of the second and fifth rotating permanent magnets 32A and 35A generate a loop-shaped magnetic flux Ψ37a that flows counterclockwise in the figure, spanning the outer circumference of these rotating permanent magnets 32A and 35A and the inner circumference of the gap G. The generation of the loop-shaped magnetic flux Ψ37a makes it easier for the magnetic flux Ψc8 to flow between two adjacent loop-shaped magnetic fluxes Ψ30a and Ψ37a in the thrust direction. As a result, the magnetic flux density of the magnetic flux Ψc8 flowing through the gap G on one side in the thrust direction increases, which in turn increases the support force Fs2.

[0144] On the other side of the thrust direction, loop-shaped magnetic fluxes Ψ20b and Ψ30b are generated, similar to the case shown in Figure 20. The generation of loop-shaped magnetic fluxes Ψ20b and Ψ30b reduces the leakage flux from the first and second fixed permanent magnets 21B and 22B, and the leakage flux from the first and second rotating permanent magnets 31B and 32B.

[0145] Furthermore, on the other side in the thrust direction, similar to the second embodiment (see Figure 15), a loop-shaped magnetic flux Ψ27b is generated that flows counterclockwise in the figure, spanning the inner circumference of the fixed permanent magnets 22B and 25B and the outer circumference of the gap G. The generation of the loop-shaped magnetic flux Ψ27b makes it easier for the magnetic flux Ψc8 to flow between two adjacent loop-shaped magnetic fluxes Ψ27b and Ψ20b in the thrust direction. In addition, the magnetic fluxes Ψ31b and Ψ34b of the first and fourth rotating permanent magnets 31B and 34B generate a loop-shaped magnetic flux Ψ36b that flows clockwise in the figure, spanning the outer circumference of these rotating permanent magnets 31B and 34B and the inner circumference of the gap G. The generation of the loop-shaped magnetic flux Ψ36b makes it easier for the magnetic flux Ψc8 to flow between two adjacent loop-shaped magnetic fluxes Ψ30b and Ψ36b in the thrust direction. As a result, the magnetic flux density of the magnetic flux Ψc8 flowing through the gap G on the other side in the thrust direction also increases, which further enhances the support force Fs2.

[0146] Other components of this embodiment are the same as those of the third embodiment, and therefore are denoted by the same reference numerals, and their descriptions are omitted. Thus, the pump 1 and electric motor 10 of this embodiment also provide the same effects and advantages as those of the third embodiment.

[0147] <Other> In the above embodiments, the case in which the magnetic levitation motor 10 is applied to the magnetic levitation pump 1 has been described, but the magnetic levitation motor 10 may be applied to other equipment other than pumps. In the first and second embodiments, the fixed permanent magnet section 20 does not need to have the fourth and fifth fixed permanent magnets 24 and 25.

[0148] The fixed permanent magnet section 20 may have at least a first fixed permanent magnet 21 and a second fixed permanent magnet 22. In this case, the first fixed permanent magnet 21 and the second fixed permanent magnet 22 may be arranged adjacent to each other in the thrust direction. Similarly, the rotating permanent magnet section 30 may have at least a first rotating permanent magnet 31 and a second rotating permanent magnet 32. In this case as well, it is preferable to arrange the first rotating permanent magnet 31 and the second rotating permanent magnet 32 ​​adjacent to each other in the thrust direction.

[0149] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims, not in the sense described above, and is intended to include all modifications in the sense and scope equivalent to the claims. [Explanation of Symbols]

[0150] 1. Magnetic levitation pump 2 Housing 4a Inlet 4b Discharge port 6 impellers 7 Bulkhead 10 Magnetic Levitation Motor 11 Casing 12 rotation axes 13 Motor section 14 Stator 15 rotors 17 Support coil 19 Control Unit 20 Fixed permanent magnet section 21 1st fixed permanent magnet 22 Second fixed permanent magnet 23 Third fixed permanent magnet 24 4th fixed permanent magnet 25 5th fixed permanent magnet 30 Rotating permanent magnet section 31. First Rotating Permanent Magnet 32. Second Rotating Permanent Magnet 33 Third Rotating Permanent Magnet 34. Fourth Rotating Permanent Magnet 35. Fifth Rotating Permanent Magnet C axis Ψc1, Ψc2, Ψc3, Ψc4 Magnetic flux due to support coils Ψc5,Ψc6,Ψc7,Ψc8 Magnetic flux due to support coils Ψ21a,Ψ21b Magnetic flux of the first fixed permanent magnet Ψ22a,Ψ22b Magnetic flux of the second fixed permanent magnet Ψ23a,Ψ23b Magnetic flux of the third fixed permanent magnet Ψ31a, Ψ31b Magnetic flux of the first rotating permanent magnet Ψ32a,Ψ32b Magnetic flux of the second rotating permanent magnet Ψ33a,Ψ33b Magnetic flux of the third rotating permanent magnet Fs1, Fs2: Support force in the thrust direction

Claims

1. A casing made of magnetic material, A rotating shaft, disposed within the casing and rotatable around a predetermined axis, A motor section having a stator provided in the casing and a rotor provided on the rotating shaft facing the stator, A fixed permanent magnet portion provided in the casing, A rotating permanent magnet portion is provided on the rotating shaft opposite to the fixed permanent magnet portion, and supports the rotating shaft in a radial direction perpendicular to the axis by the repulsive force with the fixed permanent magnet portion, A support coil provided in the casing and wound around the axis, The system includes a control unit that controls the current applied to the support coil and superimposes the magnetic flux generated by the support coil onto the magnetic fluxes of the fixed permanent magnet section and the rotating permanent magnet section, thereby applying a thrust-direction support force along the axis to the rotating shaft. The aforementioned fixed permanent magnet section is A pair of annular first fixed permanent magnets are arranged in the thrust direction on either side of the stator and are magnetized in the radial direction, A pair of annular second fixed permanent magnets are arranged on the stator side of each of the first fixed permanent magnets and are magnetized in the radial direction opposite to that of the first fixed permanent magnets, It has, The aforementioned rotating permanent magnet section is A pair of annular first rotating permanent magnets are arranged opposite to each of the pair of first fixed permanent magnets and are magnetized in the opposite direction to the first fixed permanent magnets in the radial direction, A magnetic levitation motor comprising: a pair of annular second rotating permanent magnets, each positioned opposite to a pair of the aforementioned second fixed permanent magnets, and magnetized in the radial direction opposite to the second fixed permanent magnets.

2. The aforementioned fixed permanent magnet section is The system further comprises a pair of annular third fixed permanent magnets, each of which is arranged adjacent to the stator side of the first fixed permanent magnet and adjacent to the side opposite to the stator side of the second fixed permanent magnet, and which are magnetized in opposite directions in the thrust direction. The aforementioned rotating permanent magnet section is The magnetic levitation motor according to claim 1, further comprising a pair of annular third rotating permanent magnets, each positioned opposite to a pair of the third fixed permanent magnets, and magnetized in opposite directions in the thrust direction, and magnetized in the same direction as the opposing third fixed permanent magnets.

3. The aforementioned fixed permanent magnet section is A pair of annular fourth fixed permanent magnets are arranged adjacent to the opposite side of each of the first fixed permanent magnets and are magnetized in opposite directions in the thrust direction, The system further comprises a pair of annular fifth fixed permanent magnets, each of the second fixed permanent magnets, arranged adjacent to the stator side and magnetized in opposite directions in the thrust direction. Each of the aforementioned fourth fixed permanent magnets is magnetized in the opposite direction to the third fixed permanent magnet adjacent to the stator side of the adjacent first fixed permanent magnet. The magnetic levitation motor according to claim 2, wherein each of the fifth fixed permanent magnets is magnetized in the opposite direction to the third fixed permanent magnet adjacent to the second fixed permanent magnet on the opposite side.

4. The aforementioned rotating permanent magnet section is A pair of annular fourth rotating permanent magnets are arranged opposite to each of the pair of fourth fixed permanent magnets, magnetized in opposite directions in the thrust direction, and magnetized in the same direction as the opposing fourth fixed permanent magnets, The magnetic levitation motor according to claim 3, further comprising: a pair of annular fifth rotating permanent magnets arranged opposite to each of the pair of fifth fixed permanent magnets, magnetized in opposite directions in the thrust direction and magnetized in the same direction as the opposing fifth fixed permanent magnets.

5. A housing having an inlet and an outlet for the fluid to be transferred, A magnetic levitation motor according to any one of claims 1 to 4 is provided in the housing, An impeller provided at one end of the rotating shaft in the thrust direction, A magnetic levitation pump comprising a partition wall separating the rotating shaft side and the casing side.

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