Electromagnetic rotary machine

Abstract

A bearingless motor (1), which is an electromagnetic rotating machine, has a rotor (20) and a stator (10) disposed with a gap (2) therebetween, and generates a supporting force for suspending the rotor (20) in a non-contact manner by means of an electromagnetic force or a magnetic force. The stator core (11) has a rear yoke portion (12) and a plurality of tooth portions (13). The tooth part (13) is provided with a tooth main body part (13a) and a flange-shaped tooth front end part (13b). The rotor (20) has a rotor core (21) and a plurality of permanent magnets (22). The tooth tip section (13b) has an upper-stage tooth tip section (13b1) and a lower-stage tooth tip section (13b2). The transmissivity, which is an amount indicating the ease of passage of a magnetic flux in at least one of the gap portion (2) and the core in a magnetic path that causes the stator (10) and the rotor (20) to rotate in the radial direction and the circumferential direction, decreases in one direction from one end side toward the other end side in the axial direction.

Description

Technical Field

[0001] The present invention relates to electromagnetic rotating machines such as magnetic bearings or bearingless motors. Background Art

[0002] In electromagnetic rotating machines such as magnetic bearings or bearingless motors, when the rotor axially displaces, an axial restoring force is generated between the rotor and the stator. If this restoring force is small, the stability of magnetic levitation decreases, and there are problems such as a reduction in the area where the supporting force and torque are generated between the stator and the rotor due to an increase in axial displacement, or the rotor detaching from the stator.

[0003] In Patent Document 1, it is shown that the axial cross-sectional shape of the rotor of an inner-rotor type bearingless rotating machine is trapezoidal, abacus ball-shaped, drum-shaped, or spherical, and the axial cross-sectional shape of the stator of an outer-rotor type bearingless rotating machine is trapezoidal or abacus ball-shaped. With this configuration, the axial restoring force acting between the rotor and the stator is increased.

[0004] Patent Document 1: Japanese Patent Laid-Open No. 2002-315258 Summary of the Invention

[0005] In the method of Patent Document 1, the axial restoring force is increased by setting the shape of the opposing surfaces of the rotor and the stator to, for example, a conical shape. However, when the rotor axially moves, or when the axial displacement during rotation is large, the rotor and the stator come into contact. Therefore, there are problems such as the assembly and disassembly operations taking time and effort, and a reduction in torque due to an increase in the gap between the rotor and the stator.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to obtain an electromagnetic rotating machine that does not deteriorate the assembly and disassembly properties and can increase the axial restoring force of the rotor.

[0007] To solve the above problems and achieve the object, the electromagnetic rotating machine in the present invention includes: a rotor; and a stator that is disposed with a gap therebetween relative to the rotor and generates a supporting force for non-contact suspension of the rotor by electromagnetic force or magnetic force. In the electromagnetic rotating machine, at least one of the rotor and the stator has a plurality of tooth portions formed of multiple iron cores for winding windings. The transmittance, which is a quantity representing the ease of passage of magnetic flux through at least one of the gap portion and the iron core in the magnetic circuit that causes the stator and the rotor to rotate in the radial and circumferential directions, decreases in one direction from one axial end side toward the other end side.

[0008] Advantages of the Invention

[0009] According to the electromagnetic rotating machine of the present invention, there is an effect that the assembly and disassembly properties are not deteriorated and the axial restoring force of the rotor can be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a bottom view showing the structure of a bearingless motor as the electromagnetic rotating machine of Embodiment 1.

[0011] Figure 2 is a bottom view showing the structure of a magnetic bearing as the electromagnetic rotating machine of Embodiment 1.

[0012] Figure 3 is a cross-sectional view showing the structure of a magnetic bearing as the electromagnetic rotating machine of Embodiment 1.

[0013] Figure 4 is an axonometric view showing a partial structure of a stator core of the electromagnetic rotating machine of Embodiment 1.

[0014] Figure 5 is an xy cross-sectional view showing the structure of the upper stator core of the electromagnetic rotating machine of Embodiment 1.

[0015] Figure 6 is an xy cross-sectional view showing the structure of the lower stator core of the electromagnetic rotating machine of Embodiment 1.

[0016] Figure 7 is an axonometric view showing a partial structure of a stator and a rotor of the electromagnetic rotating machine of Embodiment 1.

[0017] Figure 8 is an axonometric view showing a partial structure of a stator and a rotor of the electromagnetic rotating machine of Embodiment 1.

[0018] Figure 9 is a graph showing the relationship between the axial displacement and the axial restoring force in the electromagnetic rotating machine of Embodiment 1 and in the comparative example.

[0019] Figure 10 is an axonometric view showing a partial structure of a modified example of a stator core of the electromagnetic rotating machine of Embodiment 1.

[0020] Figure 11 is a developed view showing the structure of a modified example of the electromagnetic rotating machine of Embodiment 1.

[0021] Figure 12 is an axonometric view showing a partial structure of a stator core of the electromagnetic rotating machine of Embodiment 2.

[0022] Figure 13 is an axonometric view showing a partial structure of a stator core of the electromagnetic rotating machine of Embodiment 3.

[0023] Figure 14It is a perspective view of a part of the structure showing a modified example of the stator core of the electromagnetic rotating machine according to Embodiment 3.

[0024] Figure 15 It is a perspective view of a part of the structure showing the stator core of the electromagnetic rotating machine according to Embodiment 4.

[0025] Figure 16 It is a perspective view of a part of the structure showing the stator and rotor of the electromagnetic rotating machine according to Embodiment 5.

[0026] Figure 17 It is an xz sectional view of the structure of the electromagnetic rotating machine according to Embodiment 5.

[0027] Figure 18 It is a diagram for explaining the principle of adjusting the axial restoring force of the electromagnetic rotating machine according to Embodiment 6.

[0028] Figure 19 It is a diagram for explaining the principle of adjusting the axial restoring force of the electromagnetic rotating machine according to Embodiment 6.

[0029] Figure 20 It is a diagram for explaining the principle of adjusting the axial restoring force of the electromagnetic rotating machine according to Embodiment 6.

[0030] Figure 21 It is a diagram for explaining the principle of adjusting the axial restoring force of the electromagnetic rotating machine according to Embodiment 6. Detailed Embodiment

[0031] Hereinafter, the electromagnetic rotating machine according to the embodiment will be described in detail with reference to the drawings.

[0032] Rotating electrical machines used in industrial applications, vehicle applications, etc. generally have bearings such as rolling bearings for supporting the rotating shaft. Since the bearings are in mechanical contact with the rotating shaft and the stator, in addition to losses due to wear and the like, they can also be a cause of failures. In recent years, electromagnetic rotating machines such as magnetic bearings or bearingless motors without mechanical contact have been developed. A magnetic bearing has a function of generating a supporting force for non - contact suspension of a rotor by electromagnetic force or magnetic force. A bearingless motor has a function of a motor that generates torque and a function of a magnetic bearing that generates the above - mentioned supporting force in one magnetic circuit. In order to suspend the rotor of a magnetic bearing or a bearingless motor, it is necessary to actively control all 5 degrees of freedom except the rotation direction around the rotating shaft, or to passively make a stable structure without actively controlling some of the 5 degrees of freedom. In addition, the above - mentioned electromagnetic force or magnetic force refers to a force acting on a permanent magnet and an iron core, a force acting on a permanent magnet and an electric current, a force acting on an iron core and an electric current, etc.

[0033] A two-axis controlled magnetic bearing or bearingless motor detects the position only radially of the rotor through a sensor, and adjusts the opposing radial support force so that the detected position coincides with the target position. That is, a two-axis controlled magnetic bearing or bearingless motor performs active control only radially. Radially, when the rotation axis is set as the z-axis, there are two directions, the x-axis direction and the y-axis direction. When generating the support force, generally, on the basis of causing a varying current that contributes to the increase or decrease of the support force to flow through the winding, a bias current flows in each winding, or instead of the bias current, a permanent magnet is arranged on the magnetic circuit. Whichever method is used, the following principle holds, but in the following description, the case of using a permanent magnet is described.

[0034] A two-axis controlled magnetic bearing or bearingless motor generally has a passively stable structure in the rotation axis direction and the tilt direction of the rotor, rather than performing active control. Here, the axial direction is the direction of the z-axis, and the tilt directions are θx and θy. Hereafter, the direction to be controlled is referred to as the control direction. On the other hand, the direction that becomes stable passively without being controlled is referred to as the passive stable direction.

[0035] In an electromagnetic rotating machine such as a magnetic bearing or a bearingless motor, sometimes the rotor has a permanent magnet and the stator has an iron core, or the rotor has an iron core and the stator has a permanent magnet. For simplicity, the former case is described below.

[0036] Here, permeance is described. Permeance is also called magnetic permeability and refers to the ease of passage of magnetic flux. If permeance is set as P, magnetic permeability as μ, magnetic path length as l, and magnetic path cross-sectional area as S, then P = μS / l holds. That is, the larger the magnetic permeability μ, the wider the magnetic path cross-sectional area S, and the shorter the magnetic path length l, the larger the permeance P becomes. On the other hand, the smaller the magnetic permeability μ, the smaller the magnetic path cross-sectional area S, and the longer the magnetic path length l, the smaller the permeance P becomes. In addition, the reciprocal of the permeance P, which represents the quantity of the difficulty of passage of magnetic flux, is called magnetic resistance or reluctance. Therefore, making the permeance P decrease in one direction from one end side to the other end side in the axial direction has the same meaning as making the magnetic resistance increase in one direction from one end side to the other end side in the axial direction.

[0037] To be set to stable passively, the attractive force between the permanent magnet of the rotor and the iron core of the stator is utilized. For example, when the rotor undergoes axial displacement, a magnetic flux flows between the permanent magnet of the rotor and the iron core of the stator, which are separated by a radial clearance, generating a mutually attractive force that acts to return the axial displacement of the rotor. As a result, without control, a restoring force is generated in the direction opposite to the direction in which the axial displacement has occurred. The attractive force acting between the permanent magnet and the iron core is proportional to the distance, and thus can be considered a spring force. Hereinafter, the force acting in the axial direction will be referred to as the axial restoring force fz. In addition, the ratio of the axial restoring force fz to the axial displacement Δz will be referred to as the restoring force coefficient kz. Furthermore, hereinafter, the axial forces in the respective regions generated in the clearance will be classified as the axial restoring force f 1Z , the axial restoring force f 2Z . The total axial restoring force fz acting on the rotor becomes the sum of these axial restoring forces f 1Z , the axial restoring force f 2Z , etc.

[0038] As described above, an axial restoring force fz is generated between the rotor and the stator. However, if the value of the axial restoring force fz is small, the stability of magnetic levitation will be reduced, and problems such as the following will occur. That is, as the axial displacement increases, the area where the supporting force and torque are generated between the stator and the rotor decreases, and the rotor detaches from the stator. If the axial length of the rotor is short, this problem becomes more significant. That is, even when the rotor undergoes a small axial displacement, if the axial length of the rotor is originally short, the ratio of the area where the stator and the rotor face each other will decrease significantly. This means that due to a small axial displacement of the rotor, the ratio of the generated torque and supporting force may decrease significantly compared to the original. In the case of two-axis control type, the axial length of the rotor is mostly designed to be small compared to the radius of the rotor. Therefore, the overall device becomes flat, and it is inevitable that the axial length of the rotor relatively decreases.

[0039] Embodiment 1.

[0040] Figure 1 is a bottom view showing the structure of the bearingless motor 1 as the electromagnetic rotating machine of Embodiment 1. In Figure 1 , the z direction corresponds to the vertical direction (up and down direction), and the xy plane is perpendicular to the z axis. In Figure 1In [the figure], the xy plane of the bearingless motor 1 is observed from the lower side. The bearingless motor 1 has a stator 10 and a rotor 20. The stator 10 has a stator core 11 and a winding (not shown). The stator core 11 has a rear yoke portion 12 that forms an outer peripheral magnetic circuit and a plurality of tooth portions 13. The plurality of tooth portions 13 protrude inward from the rear yoke portion 12. Each tooth portion 13 has a tooth main body portion 13a and a plurality of flange-shaped tooth tip portions 13b that protrude from the front end of the tooth main body portion 13a toward both sides in the circumferential direction. The tooth tip portions 13b have an upper tooth tip portion 13b1 and a lower tooth tip portion 13b2, the details of which will be described later. The stator core 11 can be a thick block of a ferromagnetic material such as iron, or a laminated steel plate formed by laminating a plurality of steel plates, or a powder compact core can also be used.

[0041] The rotor 20 has a rotor core 21 and a plurality of permanent magnets 22. The rotor 20 is disposed inside the stator 10 with a gap portion 2 therebetween. For convenience, the illustration of the winding is omitted, but as the winding, two types of windings, i.e., a support winding for suspending the stator 10 and a motor winding for generating torque, can be provided, or only the support winding can be provided. Only one type of winding can be prepared, and a current for generating a support force and a current for generating torque flow in this winding. Since there are permanent magnets 22, even if no bias current flows in the winding, a biased magnetic flux passes through between the stator 10 and the rotor 20 through the gap portion 2. In addition, since there are permanent magnets 22, a magnet torque for rotating the rotor 20 can be generated, and it can function as a bearingless motor. The rotor core 21 can be a thick block of a ferromagnetic material such as iron, or a laminated steel plate formed by laminating a plurality of steel plates, or a powder compact core can also be used.

[0042] Figure 2 is a bottom view showing the structure of the magnetic bearing 3 of the electromagnetic rotating machine as the first embodiment. In Figure 2 the xy plane of the magnetic bearing 3 is observed from the lower side. Figure 3 is a cross-sectional view showing the structure of the magnetic bearing 3 of the electromagnetic rotating machine as the first embodiment. Figure 3 is cut by the xz plane of Figure 2 In the magnetic bearing 3, the rotor 20 only has the rotor core 21 and there are no permanent magnets 22. The structure of the stator 10 is the same as that of Figure 1 In Figure 2 the illustration of the winding 14 is omitted, but in Figure 3 the winding 14 is shown.

[0043] The magnetic bearing 3 has a stator 10 and a rotor 20. The stator 10 has a stator core 11 and windings 14. The stator core 11 has a rear yoke portion 12 that forms an outer peripheral magnetic circuit and a plurality of tooth portions 13. The plurality of tooth portions 13 protrude inward from the rear yoke portion 12. Each tooth portion 13 has a tooth main body portion 13a and a plurality of flange-shaped tooth tip portions 13b that protrude from the front end of the tooth main body portion 13a toward both sides in the circumferential direction. The tooth tip portion 13b has an upper tooth tip portion 13b1 and a lower tooth tip portion 13b2, the details of which will be described later.

[0044] The rotor 20 has a rotor core 21. The rotor 20 is disposed inside the stator 10 with a gap portion 2 therebetween. In this case, since no permanent magnet is disposed in the rotor 20, a bias current needs to flow through the windings 14. However, by providing a permanent magnet in either the rotor 20 or the stator 10, the bias current can be made unnecessary. In Figure 2 such a structure, there is an advantage that copper loss caused by the bias current does not occur.

[0045] Next, Figure 3 will be used to explain the principle of generating the radial supporting force of the magnetic bearing 3. In addition, in Figure 3 , the opposite surfaces of the upper tooth tip portion 13b1 and the lower tooth tip portion 13b2 with respect to the rotor core 21 are actually coplanar, but have steps for easy visual recognition of the presence of the upper and lower portions. Here, the case of generating a supporting force in the x direction will be explained. Windings 14 are wound around the tooth main body portion 13a on the positive side (right side) of the x-axis, and windings 14 are wound around the tooth main body portion 13a on the negative side (left side) of the x-axis. A bias current I plus a varying current i, i.e., I + i, flows through the winding 14 on the positive side (right side) of the x-axis, and a bias current I minus a varying current i, i.e., I - i, flows through the winding 14 on the negative side (left side) of the x-axis. At this time, the magnetic flux density can be increased or decreased in the gap portion 2. Additionally, if it is considered that the current is proportional to the magnetic flux density and the force is proportional to the square of the magnetic flux density, then if the constant is set to k, the force acting on the surface of the gap portion 2 on the positive side (right side) of the x-axis becomes k(I + i) 2 , and the force acting on the surface of the gap portion 2 on the negative side (left side) of the X-axis becomes k(I - i) 2 . The difference between these forces is (4 × k × I × i). Therefore, the rotor 20 is subjected to a force of (4 × k × I × i) in the positive x direction. That is, after flowing the bias current I, if the varying current i flowing through each tooth portion 13 is adjusted, a radial force proportional to the varying current i can be generated. When it is also desired to generate a supporting force in the y-axis direction, the varying current i flowing through the other windings can be adjusted in the same manner. As a result, it can function as a magnetic bearing that generates a radial supporting force.

[0046] Figure 4It is a perspective view showing a partial structure of the stator core 11 of the electromagnetic rotating machine according to Embodiment 1. Figure 4 The shown stator core 11 Figure 1 shows an enlarged view of a partial structure of the stator core 11 of the bearingless motor 1 shown. Additionally, Figure 4 the shown stator core 11 Figure 2 、 3 shows an enlarged view of a partial structure of the stator core 11 of the magnetic bearing 3 shown. A winding (not shown) is wound around the tooth main body portion 13a of the tooth portion 13 and energized, and by generating a radial electromagnetic supporting force on the rotor 20, torque can be generated to rotate the rotor 20.

[0047] As Figure 4 shown, the tooth tip portion 13b is provided with a flanged structure that expands the width dimension in the circumferential direction so that a large amount of magnetic flux can pass between the tooth tip portion 13b and the rotor 20 in the gap portion 2. In Embodiment 1, the width dimension of the tooth tip portion 13b is divided into two types in the up-down direction. That is, the tooth tip portion 13b has an upper tooth tip portion 13b1 as the first tooth tip portion on the positive side in the axial direction (positive side in the z direction) and a lower tooth tip portion 13b2 as the second tooth tip portion on the negative side in the axial direction (negative side in the z direction). In other words, the tooth portion 13 has: a first tooth portion as the upper tooth portion, which has an upper tooth tip portion 13b1 as the first tooth tip portion; and a second tooth portion as the lower tooth portion, which has a lower tooth tip portion 13b2 as the second tooth tip portion. And, in other words, the stator core 11 includes an upper stator core 11-1 having an upper tooth tip portion 13b1 and a lower stator core 11-2 having a lower tooth tip portion 13b2.

[0048] The width W1 of the upper tooth tip portion 13b1 is greater than the width W2 of the lower tooth tip portion 13b2. That is, in Embodiment 1, the following structure is provided, that is, the width dimension of the tooth tip portion 13b becomes shorter in one direction from the axial one end side where the upper tooth tip portion 13b1 exists to the axial other end side where the lower tooth tip portion 13b2 exists. As a result, compared with the magnetic circuit cross-sectional area S1 of the upper tooth tip portion 13b1 per unit axial length, the magnetic circuit cross-sectional area S2 of the lower tooth tip portion 13b2 becomes smaller. In Figure 4 it, the amount of two layers of the laminated structure corresponds to the unit axial length. The shaded magnetic circuit cross-sectional area S1 corresponds to the area per unit axial length of the portion of the upper tooth tip portion 13b1 facing the rotor 20. The shaded magnetic circuit cross-sectional area S2 corresponds to the area per unit axial length of the portion of the lower tooth tip portion 13b2 facing the rotor 20.

[0049] That is, the magnetic flux transmittance P through the lower teeth is smaller than the magnetic flux transmittance P through the upper teeth. In this structure, the clearance surface between the stator 10 and the rotor 20 is not conical as in Patent Document 1, so even if the rotor 20 moves axially, it will not contact the stator 10. In addition, tooth tip portions may be provided in addition to the upper tooth tip portion 13b1 and the lower tooth tip portion 13b2 so that the circumferential width of the tooth tip portion, i.e., the tooth tip portion 13b of the tooth portion 13, satisfies the condition of decreasing in one direction from one end side in the axial direction toward the other end side. For example, between the upper tooth tip portion 13b1 and the lower tooth tip portion 13b2, a middle tooth tip portion having a shorter circumferential width than the upper tooth tip portion 13b1 and a longer circumferential width than the lower tooth tip portion 13b2 may be provided. In addition, a tooth tip portion having a shorter circumferential width than the lower tooth tip portion 13b2 may be provided on the negative side in the axial direction compared to the lower tooth tip portion 13b2. This will be described later Figure 10 for illustration.

[0050] Using Figure 5 , the magnetic circuit and transmittance P in the upper stator core 11-1 will be described. Figure 5 is an xy cross-sectional view showing the structure of the upper stator core 11-1 of the electromagnetic rotating machine according to Embodiment 1. As Figure 5 shown, a circumferential magnetic circuit J around the stator 10 and the rotor 20 is formed with a clearance portion 2 interposed therebetween. The circumferential magnetic circuit J can be mainly divided into two, a radial direction and a circumferential direction. The circumferential magnetic circuit J has a tooth tip portion transmittance P1, a clearance portion transmittance P2, a rotor transmittance P3, a tooth main body portion transmittance P4, and a back yoke portion transmittance P5. If the width W1 of the upper tooth tip portion 13b1 is increased, the cross-sectional area of the magnetic circuit attempting to pass through the upper tooth tip portion 13b1 becomes larger, and the transmittance P of the tooth tip portion 13b increases.

[0051] Using Figure 6 , the magnetic circuit and transmittance P in the lower stator core 11-2 will be described. Figure 6 is an xy cross-sectional view showing the structure of the lower stator core 11-2 of the electromagnetic rotating machine according to Embodiment 1. In the lower stator core 11-2, the circumferential magnetic circuit J also has a tooth tip portion transmittance P1, a clearance portion transmittance P2, a rotor transmittance P3, a tooth main body portion transmittance P4, and a back yoke portion transmittance P5. As described above, the width W2 of the lower tooth tip portion 13b2 is smaller than the width W1 of the upper tooth tip portion 13b1. As a result, the cross-sectional area of the magnetic circuit attempting to pass through the lower tooth tip portion 13b2 becomes smaller, and the transmittance P of the tooth tip portion 13b decreases.

[0052] Figure 7Fig. 0 is a perspective view showing a partial structure of the stator 10 and the rotor 20 of the electromagnetic rotating machine according to Embodiment 1, showing a state in which the rotor 20 has a displacement of Δz in the axial direction. Figure 8 Fig. 1 is a perspective view showing a partial structure of the stator 10 and the rotor 20 of the electromagnetic rotating machine according to Embodiment 1, showing a state in which the rotor 20 has no displacement in the axial direction. Using Figure 7 and Figure 8 , the principle of increase in the axial restoring force in the case of a two-stage structure in which the front end portion 13b of the tooth is divided into an upper stage and a lower stage will be described. A model of the stator 10 and the rotor 20 cut by the xz plane is shown. In addition, for simplicity, the lines indicating the laminated structure are not shown.

[0053] When this electromagnetic rotating machine is used for applications such as a fan, a blower, or a pump, a reaction force is applied to the rotor 20 when gas or liquid is sent out from the blades mounted on the rotor 20. In addition, regardless of the presence or absence of the blades, the gravitational force mg generated by the mass of the rotor 20 itself acts on the rotor 20. In Figure 7 , Figure 8 , a case is shown in which the rotating shaft is arranged in the vertical direction and the gravitational force mg of the rotor 20 acts in the axial direction. The positive direction of the z-axis is defined as the upward vertical direction. At this time, the rotor 20 tries to move in the downward vertical direction, i.e., the negative direction of the z-axis, due to forces such as the gravitational force mg. However, as described above, when the rotor 20 has a displacement in the axial direction, an axial restoring force fz is generated in the direction opposite to the displacement. Therefore, the rotor 20 floats at the position where these forces are balanced. A part of the magnetic flux is concentrated in the lower end portion 13c1 of the tooth portion 13, and thus the axial restoring force f 1Z is generated. This axial restoring force f 1Z is also generated in a general shape without changing the width dimension of the front end portion 13b of the tooth.

[0054] On the other hand, in Embodiment 1, the width W1 of the upper-stage tooth front end portion 13b1 is made larger than the width W2 of the lower-stage tooth front end portion 13b2. Therefore, below the upper-stage tooth front end portion 13b1, in other words, in the intermediate portion 13c2 in the vertical direction of the tooth portion 13, the flange portion of the upper-stage tooth front end portion 13b1 protrudes further in the circumferential direction than the flange portion of the lower-stage tooth front end portion 13b2, and the magnetic flux is also concentrated here. The reason is that there is a difference in the transmittance P between the upper-stage tooth portion and the lower-stage tooth portion. In other words, the transmittance P decreases in one direction from one end side in the axial direction toward the other end side. Therefore, a new axial restoring force f 2Z is also generated in the intermediate portion 13c2 in the vertical direction of the tooth portion 13. As described above, by making the front end portion 13b of the tooth a two-stage structure of an upper stage and a lower stage, the axial restoring force fz increases in one direction.

[0055] In addition, as Figure 8As shown, when the rotor 20 does not produce axial displacement, there is no axial restoring force f generated due to the non-opposition of the rotor 20 and the stator 10 in the axial direction. 1Z However, there is an axial restoring force f generated by making the tooth tip 13b a two-stage structure of upper and lower sections. 2Z The above situation is described by an equation. If the resultant force of the forces acting on the rotor 20 in the axial direction is set as F Z , then this resultant force F Z becomes the gravitational force mg, the disturbance d caused by the aforementioned reaction force, etc., and the axial restoring force f 1Z and the axial restoring force f 2Z sum. The axial motion equation becomes the following equation.

[0056] F Z = -mg + d + f 1Z + f 2Z

[0057] The axial restoring force f 1Z is proportional to the axial displacement Δz. If the axial restoring force coefficient is set as kz, then f 1Z = -kz·Δz. The negative sign indicates that the rotor 20 is attracted by the stator 10 in the direction opposite to the direction of the generated displacement. The axial restoring force f 2Z is related to the magnetic flux between the stator 10 and the rotor 20 in the middle part 13c2, but it is almost independent of the axial displacement Δz of the rotor 20, so it can be regarded as a constant. If the width W1 of the upper tooth tip 13b1 is made larger than the width W2 of the lower tooth tip 13b2, then f 2Z > 0. Therefore, the axial motion equation becomes the following equation.

[0058] F Z = -mg + d - kz·Δz + f 2Z

[0059] The equilibrium position is the value of Δz when F Z = 0. It is expressed as follows.

[0060] Δz = (-mg + d + f 2Z ) / kz

[0061] When the width of the tooth tip 13b where the axial restoring force f 2Z is 0 is constant, Δz = (-mg + d) / kz, and the equilibrium position balanced by the amount of the gravitational force mg and the disturbance d is axially offset. However, as shown in Embodiment 1, when f 2Z > 0, the equilibrium position approaches Δz = 0. When the axial restoring force f 2Z balances the sum of the gravitational force mg of the rotor 20 and the disturbance d, it becomes f2Z When it is = mg-d, the levitation of the rotor 20 can continue even at the position where Δz=0. Hereinafter, for simplicity, it is considered that the disturbance d=0.

[0062] Figure 9 It is a graph showing the relationship between the axial displacement and the axial restoring force in the electromagnetic rotating machine of the first embodiment and the comparative example. In Figure 9 , the horizontal axis represents the axial displacement Δz, and it shows that as it moves further to the right of the horizontal axis, the rotor 20 is displaced more to the negative side in the axial direction compared to the origin. The vertical axis represents the axial restoring force f z , and it becomes the value of the sum of the axial restoring force f 1Z and the axial restoring force f 2Z . In Figure 9 , the values obtained by normalizing the vertical axis and the horizontal axis are shown. The thick solid line corresponds to the case of the two-stage structure with the tooth front end portions 13b in the upper and lower sections as shown in the first embodiment. The dotted line corresponds to the comparative example and corresponds to the case where the width of the tooth front end portion 13b is constant. Figure 9 It shows the result obtained by analyzing the relationship between the axial displacement and the axial restoring force by the finite element method.

[0063] In both the one-stage structure (comparative example) and the two-stage structure (first embodiment), it can be seen that the larger the axial displacement becomes, the greater the axial restoring force increases. This is the influence of the aforementioned axial restoring force f 1Z . In addition, the two-stage structure (first embodiment) further deviates from the relationship of the one-stage structure (comparative example) and increases by a certain value. This increase amount corresponds to the influence of the axial restoring force f 2Z . As long as a horizontal line is drawn at the position of the balance with gravity, the point where gravity and the axial restoring force overlap can be calculated. Q1 is the balance position of the comparative example, and Q2 is the balance position of the first embodiment. From this analysis result, it can be seen that the balance position of the first embodiment is closer to the origin compared to the comparative example.

[0064] Figure 10 It is a perspective view showing a part of the structure of a modified example of the stator core 11 of the electromagnetic rotating machine of the first embodiment. As described above, the number of stages of changing the width dimension of the tooth front end portion 13b can be set to be not 2 stages but 3 or more stages. In Figure 10 , the tooth front end portion 13b has an upper tooth front end portion 13b1, a middle tooth front end portion 13b3, and a lower tooth front end portion 13b2, and has a relationship where the width W1 of the upper tooth front end portion 13b1 > the width W3 of the middle tooth front end portion 13b3 > the width W2 of the lower tooth front end portion 13b2. In addition, the width dimension of the tooth front ends of all the laminated steel plates can be changed so that the width dimension does not change in a stepped manner but in a linear manner.

[0065] In addition, in the above description, an inner rotor type in which the stator 10 is disposed on the outside and the rotor 20 is disposed on the inside has been described. However, Embodiment 1 can also be applied to an outer rotor type in which the stator 10 is disposed on the inside and the rotor 20 is disposed on the outside. That is, in this case, by changing the width dimension of the tooth tip portion 13b of the stator 10 of the outer rotor type in multiple stages or linearly in one direction in the z direction, the same effect as described above can be obtained.

[0066] In addition, in the above description, the case where the rotor 20 has a permanent magnet and the stator 10 has an iron core has been described. However, Embodiment 1 can also be applied to the case where the rotor 20 has an iron core and the stator 10 has a permanent magnet. In this case, by changing the width dimension of the tooth tip portion of the tooth portion of the rotor of the inner rotor type or the outer rotor type in multiple stages or linearly in one direction in the z direction, the same effect as described above can be obtained.

[0067] In addition, in the above description, the case where the gravity mg of the rotor 20 is assumed and the tooth tip portion 13b is provided with a multi-stage structure so as to generate an axial restoring force f in the direction opposite to the gravity mg of the rotor 20 has been described. However, it is also possible to cope with forces other than the gravity mg. For example, for a pump in which a blade is attached to the rotor 20 to circulate a liquid, an axial reaction force is also generated. Since the direction of the reaction force is predetermined in one direction, as long as the width dimension of the tooth tip portion 13b is shortened in one direction so as to increase the axial restoring force in the direction opposite to the direction of the reaction force. 2Z has been described.

[0068] In addition, in Figure 1 , a surface magnet type in which the permanent magnet 22 is disposed on the surface of the rotor 20 has been shown. However, Embodiment 1 can also be applied to an embedded magnet type in which the permanent magnet 22 is disposed in the core of the rotor 20. In addition, Embodiment 1 can also be applied to a motor that does not have a permanent magnet 22 on the rotor 20 side and uses reluctance torque.

[0069] In addition, it is preferably designed that the axial length (length in the axial direction) of the rotor 20 is shorter than the length of the radius of the rotor 20. By setting it in the above manner, the restoring force coefficient kz and the axial restoring force f 1Z increase. And, based on the effect of the axial restoring force f 2Z , the equilibrium position is closer to the origin.

[0070] Figure 11 is an exploded view showing the structure of a modified example of the electromagnetic rotating machine according to Embodiment 1. In Figure 11In [the structure], a sensor 16 is disposed in a region 15 between the front end portions 13b2 of adjacent lower-stage teeth. The slot opening width in the region 15 between the front end portions 13b2 of adjacent lower-stage teeth is expanded, so that a space for arranging various components can be ensured. In the region 15, a base for the sensor 16, a holding mechanism, wiring for the sensor 16, a jumper wire of a winding, or a refrigerant pipe for cooling can be arranged. In addition, a sensor 16 for detecting the surrounding temperature, magnetic flux density, or distance from the rotor 20 can also be arranged. The sensor 16 can be a Hall element, a thermocouple, or an eddy current displacement sensor. In this case, on the lower-stage side where the slot opening width is expanded, the magnetic flux from the permanent magnet 22 of the rotor 20 to the sensor of the Hall element, or the magnetic flux from the eddy current sensor to the rotor 20 is easily transmitted. The reason is that if the flange portion of the tooth portion 13 protrudes significantly, since magnetic flux flows in the flange portion, the sensitivity of the sensor 16 decreases, but this phenomenon can be suppressed by expanding the slot opening width on the lower-stage side. In addition, as Figure 10 shown, in the case of having tooth front end portions of three or more stages, it becomes difficult to arrange the sensor 16 on the upper-stage tooth front end portion 13b1 side from the perspective of space, but the same effect can also be obtained by arranging it on the middle-stage tooth front end portion 13b3 side and the lower-stage tooth front end portion 13b2 side. At this time, if the sensor 16 is arranged on the lower-stage tooth front end portion 13b2 side where the slot opening width is the largest, the above effect can be obtained optimally.

[0071] As described above, according to Embodiment 1, the transmittance P, which represents the easiness of magnetic flux passing through at least one of the gap portion and the iron core in the surrounding magnetic circuit J in which the stator 10 and the rotor 20 rotate around the radial direction and the circumferential direction, decreases in one direction from one axial end side to the other end side. Specifically, the width dimension of the tooth front end portion 13b of the tooth portion 13 is changed in multiple stages or linearly in one direction in the z direction. Therefore, it is not necessary to make the gap surface between the stator 10 and the rotor 20 conical or the like, the assembly and disassembly performance will not deteriorate, and the axial restoring force of the rotor 20 can be increased in one direction. In addition, the interval of the gap between the rotor 20 and the stator 10 can be reduced, so that magnetic flux easily passes between the stator 10 and the rotor 20, and the current required to generate the same torque and supporting force can be reduced. As a result, effects such as reduced heat generation and increased efficiency are obtained.

[0072] In addition, according to Embodiment 1, an axial restoring force f can be generated even if the rotor 20 does not displace axially. 2Z As Figure 8 shown, if the gravitational force mg of the rotor 20 and the axial restoring force f are in a state where the rotor 20 does not displace axially. 2ZWhen balanced, all the axial regions in the stator 10 and the rotor 20 face each other. Therefore, the supporting force and torque generated when the current is the same between the stator 10 and the rotor 20 increase. As a result, the following effect is obtained, that is, the copper loss when generating the same supporting force and torque is reduced.

[0073] In addition, according to Embodiment 1, only the width of the tooth tip portion 13b is changed, and the inner diameter of the stator 10 and the outer diameter of the rotor 20 are not changed. Therefore, the movable region of the rotor 20 is not reduced at all. That is, if the inner diameter of the stator 10 and the outer diameter of the rotor 20 are changed, when the rotor 20 is displaced in the radial direction, the axial direction or the inclined direction, the rotor 20 and the stator 10 come into contact at the protruding portions or the portions where the gap becomes narrow, and the problem of reduction of the movable region of the rotor 20 occurs. According to Embodiment 1, this drawback does not occur, and the axial force generated in the rotor 20 can be increased.

[0074] Embodiment 2.

[0075] Figure 12 It is a perspective view showing a partial structure of the stator core 11 of the electromagnetic rotating machine according to Embodiment 2. In Figure 12 In order to improve visual recognition, the direction of the z-axis is reversed by 180 degrees with respect to Figures 1 to 4 the case of, and a perspective view observed from below is shown. In Embodiment 2, the tooth main body portion 13a is also set to a multi-stage structure of two or more stages, and the circumferential width W4 of the upper tooth main body portion 13a1 as the first tooth main body portion is made larger than the circumferential width W5 of the lower tooth main body portion 13a2 as the second tooth main body portion. In addition, the rear yoke portion 12 is also set to a multi-stage structure of two or more stages, and the radial width W6 of the upper rear yoke portion 12-1 as the first rear yoke portion is made larger than the width W7 of the lower rear yoke portion 12-2 as the second rear yoke portion.

[0076] Therefore, compared with the upper stage, the magnetic circuit cross-sectional area of the lower stage becomes smaller, and the transmittance P becomes smaller. Therefore, the magnetic flux easily passes between the upper stage of the stator 10 and the rotor 20 compared with between the lower stage of the stator 10 and the rotor 20, and the axial magnetic flux and the axial restoring force f 2Z increase. Therefore, if the structure of Embodiment 2 is adopted in accordance with the change in the width dimension of the tooth tip portion 13b, the axial restoring force f 2Z further increases. In addition, by shortening the width dimensions of the tooth main body portion 13a and the rear yoke portion 12, the weight reduction of the entire device is achieved.

[0077] In addition, in Figure 12 the case where the width dimensions of both the tooth main body portion 13a and the rear yoke portion 12 are changed is shown, but the width dimension of only either one may be changed. In addition, in Figure 12Although not shown in the figure, when the winding is wound around the tooth portion 13, the width dimension on the lower side becomes shorter, thereby enabling the circumference of the winding to be shortened. As a result, the resistance and copper loss can be reduced. In addition, when the winding is wound around the lower side, the angle is greater than 90 degrees, so winding expansion can be suppressed. As a result, the area of the winding end portion can be reduced, and on the basis of the above-mentioned reduction in copper loss, miniaturization and weight reduction of the entire device can be achieved. In addition, by having a difference in the width of the tooth tip portion 13b, the effects described in Embodiment 1 can also be obtained. However, it is also possible not to have a difference in the width of the tooth tip portion 13b.

[0078] In addition, the width W5 of the lower tooth main body portion 13a2 becomes shorter, which also suppresses the winding expansion of the winding, thereby enabling the slot space therebetween to be ensured. As a result, in the same manner as in Embodiment 1, the sensor 16, other holding mechanisms, etc. can be arranged at this position. In addition, when the sensor 16 is long in the radial direction and must be arranged across both between the tooth tip portions 13b and between the tooth main body portions 13a, the area of the sensor 16 can be ensured throughout the entire length.

[0079] As described above, according to Embodiment 2, in order to decrease the transmittance P in one direction from one end side in the axial direction toward the other end side, the circumferential width W4 of the upper tooth main body portion 13a1 is made larger than the circumferential width W5 of the lower tooth main body portion 13a2, and the radial width W6 of the upper yoke portion 12-1 is made larger than the width W7 of the lower yoke portion 12-2. Therefore, the assembly and disassembly property is not deteriorated, the axial restoring force of the rotor 20 can be increased in one direction, and the arrangement position of the sensor 16 can be ensured.

[0080] Embodiment 3.

[0081] Figure 13 It is a perspective view showing a partial structure of the stator core 11 of the electromagnetic rotating machine according to Embodiment 3. Figure 14 It is a perspective view showing a partial structure of a modified example of the stator core 11 of the electromagnetic rotating machine according to Embodiment 3. In Figure 13 , Figure 14 In, Figure 12 Similarly, a perspective view of the stator core 11 observed from below is shown. In addition, for simplicity, the lines indicating the laminated structure are not shown.

[0082] In Figure 13 In, a groove portion 17 is provided on the gap surface of the lower tooth tip portion 13b2 facing the rotor 20. Since the groove portion 17 is not wound with a winding but becomes a slot portion, this groove portion 17 is also referred to as a dummy slot. In Figure 11Among them, the slot portion 17 is only provided in the lower segment, so an upper exposed surface 17a is formed on the upper segment side of the slot portion 17 where a part of the front end portion 13b1 of the upper segment teeth is exposed. According to this structure, a magnetic flux that passes obliquely between the upper exposed surface 17a of the front end portion 13b1 of the upper segment teeth and the rotor 20 is generated. As a result, the axial restoring force f 2Z is further increased. It can also be considered that through the slot portion 17, the magnetic flux hardly passes through a part of the front end portion 13b2 of the lower segment teeth, and the transmittance P is reduced.

[0083] In Figure 14 Among them, a slot portion 17 as the second slot portion is provided on the clearance surface of the front end portion 13b2 of the lower segment teeth, and a slot portion 18 as the first slot portion is provided on the clearance surface of the front end portion 13b1 of the upper segment teeth. In addition, the size of the slot portion 17 is made larger than the size of the slot portion 18. The size of the slot portion 17 is the width dimension L1 or the depth dimension L2. Both can be changed, or only the size of a single one can be changed. By setting it in the above manner, Figure 13 similarly, the upper exposed surface 17a can be generated.

[0084] As described above, according to the third embodiment, in order to reduce the transmittance P in one direction from one axial end side to the other end side, the slot portion 17 is provided on the clearance surface of the front end portion 13b2 of the lower segment teeth. Therefore, not only does it have the effect of increasing the axial restoring force, but it can also adjust the waveform or peak value of the cogging torque generated between the stator 10 and the rotor 20 when there is no power supply. Generally, it is preferable that the cogging torque is small, but the effect of reducing the cogging torque can also be obtained at the same time. In addition, by providing a difference in the width of the front end portion 13b of the teeth or the width of the tooth main body portion 13a, the effects described in the first embodiment and the second embodiment can also be obtained. However, only by designing the slot portion 17, the effect of increasing the axial restoring force in one direction can also be achieved.

[0085] Embodiment 4.

[0086] Figure 15It is a perspective view showing a partial structure of the stator core 11 of the electromagnetic rotating machine according to Embodiment 4. In Embodiment 4, in the upper stator core 11-1 and the lower stator core 11-2, the material of the core is changed. The upper stator core 11-1 uses a high magnetic flux density material, and the lower stator core 11-2 uses a low magnetic flux density material. The magnetic flux density of the upper stator core 11-1 is greater than that of the lower stator core 11-2. The upper stator core 11-1 has an upper tooth front end portion 13b1, and the lower stator core 11-2 has a lower tooth front end portion 13b2. The width of the upper tooth front end portion 13b1 is greater than the width of the lower tooth front end portion 13b2. The high magnetic flux density material refers to a material having a large magnetic flux density value relative to the same magnetic field strength. For example, a grain-oriented electrical steel sheet can be used for the upper stator core 11-1, and a non-grain-oriented electrical steel sheet can be used for the lower stator core 11-2. In addition, by changing the duty ratio of the laminated steel sheets, the characteristics of the magnetic flux density corresponding to the magnetic field strength of the entire region can be changed. This means that, for example, the difference is set such that the duty ratio of the upper stator core 11-1 is 96% and the duty ratio of the lower stator core 11-2 is 92%. Even if the individual laminated steel sheets are of the same material, the magnetic characteristics of the entire region can be changed. This change can be said to change the magnetic permeability. As described above, since the transmittance P is a function of the magnetic permeability, as a result, the transmittance P can be changed in the axial direction.

[0087] As described above, according to Embodiment 4, in order to decrease the transmittance P in one direction from one end side to the other end side in the axial direction, the magnetic flux density of the upper stator core 11-1 is made greater than that of the lower stator core 11-2. Therefore, the magnetic flux is further concentrated on the upper stator core 11-1 side, and the magnetic flux passing obliquely through the gap portion 2 increases. As a result, the axial restoring force f 2Z generated between the rotor 20 and the stator 10 is further increased. In addition, it is preferable to apply the shape designs described in Embodiments 1 to 3, but an effect can also be obtained only by changing the material.

[0088] Embodiment 5.

[0089] Figure 16 It is a perspective view showing a partial structure of the stator and the rotor of the electromagnetic rotating machine according to Embodiment 5. Figure 17 It is an xz cross-sectional view showing the structure of the electromagnetic rotating machine according to Embodiment 5. In Figure 16In [the figure], for visual recognition, an oblique view observed from the lower part in the axial direction is shown. In Embodiment 5, the inner diameter of the stator core 11 or the gap length between the stator 10 and the rotor 20 is changed in multiple stages or linearly so as to become shorter in one direction from one end side in the axial direction toward the other end side. If the observation method is changed, it can be said that the gap length is changed in multiple stages or linearly so as to become longer in one direction from one end side in the axial direction toward the other end side. Specifically, the inner diameter D3 of the upper stator core 11-1 is different from the inner diameter D2 of the lower stator core 11-2, and the inner diameter D3 of the upper stator core 11-1 is smaller than the inner diameter D2 of the lower stator core 11-2. The inner diameter of the stator core 11 is also referred to as the inner diameter of the tooth tip portion 13b. If the upper teeth of the tooth portion 13 are the first tooth portion and the lower teeth of the tooth portion 13 are the second tooth portion, it can be considered that the first tooth portion having the first tooth tip portion and the second tooth portion having the second tooth tip portion with an inner diameter larger than that of the first tooth tip portion are arranged in the axial direction. Preferably, the gap in the second tooth portion is wider than the gap in the first tooth portion, and the second tooth portion is arranged vertically below. In addition, the case where the gap length is expressed as long or short and the case where the gap is expressed as wide or narrow have the same meaning.

[0090] In Embodiment 5, the intermediate portion 13c2, which is located in the upper stator core 11-1 and protrudes and can be visually recognized compared with the lower stator core 11-2, is formed not only in the circumferential direction but also in the radial direction. That is, a part of the magnetic flux between the rotor 20 and the stator 10 obliquely passes through the intermediate portion 13c2 in the radial direction. Therefore, the axial force generated in the rotor 20 increases due to the presence of the intermediate portion 13c2 in the radial direction. In addition, in Embodiment 5, as shown in Embodiment 1, the width of the upper tooth tip portion 13b1 is larger than the width of the lower tooth tip portion 13b2, and the intermediate portion 13c2 in the circumferential direction is also formed. That is, by changing the width of the tooth tip portion 13b in the upper and lower stages, the axial force generated in the rotor 20 can be further increased. However, even if the width of the tooth tip portion 13b is not changed in the upper and lower stages and only the inner diameter of the stator core 11-2 is changed in the upper and lower stages, the same effect as in Embodiment 1 can be obtained.

[0091] In Embodiment 5, the inner diameter of the stator core 11 is set to D3 < D2. Further, if the outer diameter of the rotor 20 is set to D1, then D1 < D3 is satisfied. As a result, even if the rotor 20 is axially movable, the rotor 20 does not contact the stator 10. As a result, the assemblability and disassemblability are not deteriorated. Further, in Patent Document 1, both the inner diameter of the stator 10 and the outer diameter of the rotor 20 are changed. Therefore, it is necessary to prepare a plurality of shapes of both the stator 10 and the rotor 20, increasing the manufacturing cost. However, in Embodiment 5, only the shape of one of the stator 10 and the rotor 20 is changed, so that an increase in the manufacturing cost can be suppressed. In particular, manufacturing magnets having different diameters or magnets having an inclined shape is difficult. However, in Embodiment 5, only the inner diameter of the stator core 11 needs to be changed, and an increase in the manufacturing cost of the magnets does not occur. Further, the difference between the inner diameter D3 and the inner diameter D2 of the stator 10 may be, for example, about 0.1 mm to 1 mm, or there may be almost no difference in shape. For example, after the upper stator core 11-1 having a small inner diameter is manufactured at one time, the inner diameter can be expanded by additional processing of this part to manufacture the lower stator core 11-2.

[0092] Further, the change in the configuration as described above can also be explained in terms of the gap length. The magnetic permeability of the gap portion 2 formed of air is sufficiently smaller than the magnetic permeability of the iron core. That is, the magnetic path length of the gap portion 2 greatly affects the transmittance P. If the gap length of the upper stator core 11-1 is set to G1 and the gap length of the lower stator core 11-2 is set to G2, then G1 < G2. That is, the magnetic path length of the gap portion 2 is short in the upper stator core 11-1 and the magnetic path length of the gap portion 2 is long in the lower stator core 11-2. Therefore, it can also be considered that the transmittance P decreases in one direction from one end side in the axial direction toward the other end side. In Embodiment 5, the diameter of the rotor 20 does not change. Therefore, even if the rotor 20 moves axially, the values of G1 and G2 are constant and the magnitude relationship does not change.

[0093] In addition, the case of an outer rotor type in which the stator 10 is disposed on the inner side and the rotor 20 is disposed on the outer side, and the shape of the stator 10 is changed by the axial position is equivalent to changing the outer diameter of the stator 10.

[0094] As described above, according to Embodiment 5, in order to decrease the transmittance P in one direction from one axial end side toward the other end side, the inner diameter of the stator core or the gap length between the stator 10 and the rotor 20 is changed in multiple stages or linearly so as to become shorter in one direction from one axial end side toward the other end side. Therefore, the assemblability and disassemblability are not deteriorated, and the axial restoring force of the rotor 20 can be increased in one direction. In addition, the interval of the gap between the rotor 20 and the stator 10 can be decreased, so that magnetic flux easily passes between the stator 10 and the rotor 20, and the current required to generate the same torque and supporting force can be reduced. As a result, effects such as a reduction in heat generation and an increase in efficiency are obtained.

[0095] Embodiment 6.

[0096] Figure 18 FIG. is a diagram for explaining the principle of adjusting the axial restoring force of the electromagnetic rotating machine according to Embodiment 6. Figure 19 FIG. is a diagram for explaining the principle of adjusting the axial restoring force of the electromagnetic rotating machine according to Embodiment 6. In Figure 18 and Figure 19 , the rotor 20 has been displaced in the -z direction, and in Figure 18 and Figure 19 , the direction of the current flowing in the winding 14 is different. Figure 20 FIG. is a diagram for explaining the principle of adjusting the axial restoring force of the electromagnetic rotating machine according to Embodiment 6. Figure 21 FIG. is a diagram for explaining the principle of adjusting the axial restoring force of the electromagnetic rotating machine according to Embodiment 6. In Figure 20 and Figure 21 , the rotor 20 has not been displaced, and in Figure 20 and Figure 21 , the direction of the current flowing in the winding 14 is different.

[0097] Normally, in the case where there is no axial displacement of the rotor 20, no axial restoring force is generated in the rotor 20. However, as described above, the transmittance P in the magnetic path that causes the stator 10 and the rotor 20 to rotate in the radial and circumferential directions, that is, the width dimension of the tooth tip portion 13b of the tooth portion 13, the circumferential width of the tooth main body portion 13a, the inner diameter of the tooth tip portion 13b, or the material of the stator core 11, etc. is changed in multiple stages or linearly in one direction in the z direction. Therefore, even without the axial displacement of the rotor 20, an axial restoring force is generated. This is caused by the bias magnetic flux generated between the rotor 20 and the stator 10 through a bias current or a magnet. As described above, there are an axial restoring force f 1Z that is generated in proportion to the axial displacement of the rotor 20 and an axial restoring force f 2Z that is constantly generated regardless of the axial displacement, but both of them can be increased or decreased by the d-axis current.

[0098] In Figures 18 to 21 , a case is shown where the rotor 20 has a permanent magnet 22. In Figure 18 , a case is shown where a positive d-axis current flows in the winding 14 so as to enhance the magnetic flux Φ1 generated by the permanent magnet 22. At this time, the magnetic flux Φ2 generated by the winding 14 shown by the dashed line further enhances the magnetic flux Φ1 generated by the permanent magnet 22 shown by the solid line. As a result, the axial restoring force f 1Z and the axial restoring force f 2Z increase. On the other hand, in Figure 19 , the orientation of the magnetic flux Φ2 generated by the winding 14 shown by the dashed line is opposite to that of the magnetic flux Φ1 generated by the permanent magnet 22 shown by the solid line, and they weaken each other. As a result, the axial restoring force f 1Z and the axial restoring force f 2Z decrease.

[0099] Figure 20 And Figure 21 show a case where z = 0 where the rotor 20 does not generate displacement in the axial direction. At this time, the axial restoring force f 1Z becomes 0. However, an axial restoring force f 2Z is generated, which can be increased or decreased by the d-axis current. In Figure 20 , a positive d-axis current flows in the winding 14 so as to enhance the magnetic flux Φ1, and the axial restoring force f 2Z increases. In Figure 21 , a negative d-axis current flows in the winding 14 so as to weaken the magnetic flux Φ1, and the axial restoring force f 2Z decreases.

[0100] This is explained by an equation. Let the d-axis current be i d . In addition, the axial restoring force f 1Z is changed to (1 + k Zi1 ·i d ) times by the d-axis current. Here, k Zi1 is a coefficient representing the ratio of the change in the axial restoring force f 1Z by the d-axis current. In addition, it is assumed that the axial restoring force f 2Z is changed to (1 + k Zi2 ·i d ) times by the d-axis current. Here, k Zi2 is a coefficient representing the ratio of the change in the axial restoring force f 2Z by the d-axis current. The axial equation of motion becomes the following equation.

[0101] F Z = -mg - k Z (1 + kZi1 ·i d )f 1Z +(1 + k Zi2 ·i d )f 2Z

[0102] In the case of no axial displacement (z = 0), the axial equation of motion becomes the following equation.

[0103] F Z = -mg+(1 + k Zi2 ·i d )f 2Z

[0104] Therefore, in any case of z < 0 and z = 0, if there is a control device for increasing or decreasing the d-axis current id, the resultant axial force F Z acting on the rotor 20 can be adjusted. In addition, in the case of z > 0, the resultant axial force F Z acting on the rotor 20 can also be adjusted in the same manner.

[0105] For stable magnetic levitation, it is important to reduce the vibration of the rotor 20. Therefore, it is sufficient to have a control device that detects the axial vibration of the rotor 20 and increases or decreases the d-axis current flowing in the winding 14 in accordance with the detected vibration. That is, according to Embodiment 6, even without axial displacement, the axial restoring force can be adjusted to reduce the axial vibration.

[0106] The structure shown in the above embodiments represents a part of the content of the present invention, and can also be combined with other known technologies, and can be appropriately combined within the scope not departing from the gist of the present invention, or a part of the structure can be omitted or changed.

[0107] Description of reference numerals

[0108] 1 Bearingless motor, 2 Gap portion, 3 Magnetic bearing, 10 Stator, 11, 11-1, 11-2 Stator core, 12 Rear yoke portion, 12-1 Upper rear yoke portion, 12-2 Lower rear yoke portion, 13 Tooth portion, 13a Tooth main body portion, 13a1 Upper tooth main body portion, 13a2 Lower tooth main body portion, 13b Tooth front end portion, 13b1 Upper tooth front end portion, 13b2 Lower tooth front end portion, 13b3 Middle tooth front end portion, 13c1 Lower end portion, 13c2 Intermediate portion, 14 Winding, 15 Region, 16 Sensor, 17, 18 Slot portion, 17a Upper exposed surface, 20 Rotor, 21 Rotor core, 22 Permanent magnet, fz, f 1Z 、f 2Z Axial restoring force, kz Restoring force coefficient, Δz Axial displacement.

Claims

1. An electromagnetic rotating machine, comprising: a rotor; and a stator disposed with a gap therebetween relative to the rotor, generating a supporting force for non - contact suspension of the rotor by electromagnetic force or magnetic force, wherein the electromagnetic rotating machine is characterized in that at least one of the rotor and the stator has a plurality of tooth portions formed of multi - segment iron cores for winding windings, a transmittance, which is a quantity representing the easiness of magnetic flux passing through at least one of the gap portion and the iron core in a magnetic circuit causing the stator and the rotor to rotate in the radial and circumferential directions, decreases in one direction from one end side in the axial direction toward the other end side.

2. The electromagnetic rotating machine according to claim 1, wherein The width in the circumferential direction at the front end portion of the tooth portion, i.e., the tooth front end portion, decreases in one direction from one axial end side toward the other end side.

3. The electromagnetic rotating machine according to claim 2, wherein Each of the tooth portions axially arranges a first tooth portion having a first tooth front end portion and a second tooth portion having a second tooth front end portion with a smaller width in the circumferential direction than the first tooth front end portion.

4. The electromagnetic rotating machine according to claim 3, wherein It is configured such that the second tooth portion is vertically below the first tooth portion.

5. The electromagnetic rotating machine according to claim 1, wherein Each of the tooth portions has a first tooth portion and a second tooth portion axially arranged. The width in the circumferential direction of the second tooth main body portion in the second tooth portion is smaller than the width in the circumferential direction of the first tooth main body portion in the first tooth portion, or The radial width of the second yoke portion arranged on the outer peripheral side of the second tooth main body portion is smaller than the radial width of the first yoke portion arranged on the outer peripheral side of the first tooth main body portion.

6. The electromagnetic rotating machine according to claim 1, wherein Each of the tooth portions axially arranges a first tooth portion having a first tooth front end portion and a second tooth portion having a second tooth front end portion. The second tooth front end portion has a groove portion on the surface facing the stator or the rotor.

7. The electromagnetic rotating machine according to claim 1, wherein Each of the tooth portions axially arranges a first tooth portion having a first tooth front end portion and a second tooth portion having a second tooth front end portion. The first tooth front end portion has a first groove portion on the surface facing the stator or the rotor. The second tooth front end portion has a second groove portion on the surface facing the stator or the rotor. The width in the circumferential direction or the radial length of the second groove portion is longer than the width in the circumferential direction or the radial length of the first groove portion.

8. The electromagnetic rotating machine according to claim 1, wherein Each of the tooth portions has a first tooth portion and a second tooth portion axially arranged. The material of the iron core including the first tooth portion has a higher magnetic flux density generated in the same magnetic field strength compared to the material of the iron core including the second tooth portion.

9. The electromagnetic rotating machine according to claim 1, wherein The inner diameter of the front end portion of the tooth portion, i.e., the tooth front end portion, or the length of the gap portion, i.e., the gap length, becomes shorter in one direction from one axial end side toward the other end side.

10. The electromagnetic rotating machine according to claim 9, characterized in that, Each of the tooth portions axially arranges a first tooth portion having a first tooth front end portion and a second tooth portion having a second tooth front end portion with a larger inner diameter than the first tooth front end portion.

11. The electromagnetic rotating machine according to claim 3, characterized in that, A sensor is arranged between adjacent second tooth front end portions.

12. The electromagnetic rotating machine according to claim 5, characterized in that, A sensor is arranged between adjacent second tooth main body portions.

13. The electromagnetic rotating machine according to any one of claims 1 to 12, characterized in that, It has a control device that adjusts the d-axis current flowing in the winding to increase or decrease the force with which the rotor is attracted axially relative to the stator.

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