Electromagnetic Rotating Machine

Abstract

The bearingless motor (1) as an electromagnetic rotating machine includes a rotor (20) and a stator (10) arranged across a gap (2), and generates a supporting force for levitating the rotor (20) without contact by electromagnetic force or magnetic force. The stator core (11) includes a back yoke portion (12) and a plurality of teeth portions (13). The teeth portions (13) include a teeth main body portion (13a) and a brim-shaped teeth tip portion (13b). The rotor (20) includes a rotor core (21) and a plurality of permanent magnets (22). The teeth tip portion (13b) includes an upper stage teeth tip portion (13b1) and a lower stage teeth tip portion (13b2). Permeance, which is a quantity indicating the ease with which magnetic flux passes through at least one of the gap portion (2) and the iron core in a magnetic path that circles the stator (10) and the rotor (20) in the radial and circumferential directions, decreases in one direction from one end to the other end in the axial direction.

Description

[Technical field]

[0001] This disclosure relates to electromagnetic rotating machines, such as magnetic bearing or bearingless motors. [Background technology]

[0002] In electromagnetic rotating machines such as magnetic bearings or bearingless motors, when the rotor is displaced in the axial direction, an axial restoring force is generated between the rotor and the stator. If this restoring force is small, problems such as a decrease in the stability of magnetic levitation, a decrease in the area that generates the supporting force and torque between the stator and rotor due to an increase in axial displacement, or the rotor slipping off the stator may occur.

[0003] Patent Document 1 discloses that the cross-sectional shape along the axial direction of the rotor of an inner rotor type bearingless rotating machine is trapezoidal, abacus bead shaped, drum shaped or spherical, and that the cross-sectional shape along the axial direction of the stator of an outer rotor type bearingless rotating machine is trapezoidal or abacus bead shaped, and that such a structure increases the axial restoring force acting between the rotor and stator. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-315258 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the method of Patent Document 1, the axial restoring force is increased by, for example, tapering the shape of the opposing surfaces of the rotor and stator, but when the rotor is moved in the axial direction or when the axial displacement during rotation is large, the rotor and stator come into contact with each other. This requires time and effort for assembly and disassembly, and problems such as a decrease in torque due to an increase in the gap between the rotor and stator occur.

[0006] The present disclosure has been made in consideration of the above, and has an object to provide an electromagnetic rotating machine that can increase the axial restoring force of the rotor without compromising assembly and disassembly. [Means for solving the problem]

[0007] In order to solve the above problems and achieve the object, the electromagnetic rotating machine disclosed herein includes a rotor and a stator disposed across a gap from the rotor, and generates a support force for levitating the rotor without contact by electromagnetic or magnetic force. At least one of the rotor and the stator of the electromagnetic rotating machine includes a plurality of teeth made of multiple stages of iron cores for winding a winding. Permeance, which is a quantity representing the ease with which magnetic flux passes through at least one of the gap and the iron core in a magnetic path that circles the stator and rotor in the radial and circumferential directions, is given by: At least one of the following is changed: the circumferential width of the tooth tip portion, which is the tip portion of the tooth portion; the circumferential width of the tooth main body portion; the radial width of the back yoke portion disposed on the outer periphery of the tooth main body portion; the circumferential width or radial length of the groove portion at the tooth tip portion; and the magnetic permeability of the tooth portion. The diameter decreases in one direction from one end to the other end in the axial direction. Effect of the Invention

[0008] According to the electromagnetic rotating machine of the present disclosure, it is possible to advantageously increase the axial restoring force of the rotor without compromising ease of assembly and disassembly. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a bottom view showing a configuration of a bearingless motor as an electromagnetic rotating machine according to a first embodiment. [Diagram 2] FIG. 1 is a bottom view showing a configuration of a magnetic bearing as an electromagnetic rotating machine according to a first embodiment. [Diagram 3] FIG. 1 is a cross-sectional view showing a configuration of a magnetic bearing as an electromagnetic rotating machine according to a first embodiment. [Figure 4] FIG. 1 is a perspective view showing a partial configuration of a stator core of an electromagnetic rotating machine according to a first embodiment; [Diagram 5] FIG. 1 is an xy sectional view showing a configuration of an upper stage stator core of an electromagnetic rotating machine according to a first embodiment. [Figure 6]FIG. 1 is an xy sectional view showing a configuration of a lower stator core of an electromagnetic rotating machine according to a first embodiment. [Figure 7] FIG. 1 is a perspective view showing a partial configuration of a stator and a rotor of an electromagnetic rotating machine according to a first embodiment; [Figure 8] FIG. 1 is a perspective view showing a partial configuration of a stator and a rotor of an electromagnetic rotating machine according to a first embodiment; [Figure 9] Graph showing the relationship between axial displacement and axial restoring force in the electromagnetic rotating machine of the first embodiment and a comparative example. [Figure 10] FIG. 13 is a perspective view showing a partial configuration of a modified example of a stator core of the electromagnetic rotating machine according to the first embodiment. [Figure 11] FIG. 1 is a development view showing a configuration of a modified example of the electromagnetic rotating machine according to the first embodiment. [Figure 12] FIG. 11 is a perspective view showing a partial configuration of a stator core of an electromagnetic rotating machine according to a second embodiment. [Figure 13] FIG. 11 is a perspective view showing a partial configuration of a stator core of an electromagnetic rotating machine according to a third embodiment. [Figure 14] FIG. 13 is a perspective view showing a partial configuration of a modified example of a stator core of an electromagnetic rotating machine according to a third embodiment. [Figure 15] FIG. 13 is a perspective view showing a partial configuration of a stator core of an electromagnetic rotating machine according to a fourth embodiment. [Figure 16] FIG. 13 is a perspective view showing a partial configuration of a stator and a rotor of an electromagnetic rotating machine according to a fifth embodiment. [Figure 17] FIG. 13 is an xz sectional view showing the configuration of an electromagnetic rotating machine according to a fifth embodiment. [Figure 18] FIG. 13 is a diagram for explaining the principle of adjusting the axial restoring force of the electromagnetic rotating machine according to the sixth embodiment. [Figure 19] FIG. 13 is a diagram for explaining the principle of adjusting the axial restoring force of the electromagnetic rotating machine according to the sixth embodiment. [Figure 20] FIG. 13 is a diagram for explaining the principle of adjusting the axial restoring force of the electromagnetic rotating machine according to the sixth embodiment. [Figure 21] FIG. 13 is a diagram for explaining the principle of adjusting the axial restoring force of the electromagnetic rotating machine according to the sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An electromagnetic rotating machine according to an embodiment will be described below in detail with reference to the drawings.

[0011] Rotating electric machines used in industry, vehicles, etc. generally have bearings such as rolling bearings to support the rotating shaft. Since the bearings are in mechanical contact with the rotating shaft and the stator, losses occur due to wear and the like, and they also cause failures. In recent years, electromagnetic rotating machines such as magnetic bearings and bearingless motors that do not have mechanical contact have been developed. Magnetic bearings have the function of generating a support force for levitating the rotor without contact using electromagnetic or magnetic forces. Bearingless motors have the function of an electric motor that generates torque and the function of a magnetic bearing that generates the aforementioned support force in one magnetic circuit. In order to levitate the rotor of a magnetic bearing or bearingless motor, it is necessary to actively control all five degrees of freedom except the direction of rotation around the rotating shaft, or to have a passive and stable structure without actively controlling some of the five degrees of freedom. The above-mentioned electromagnetic or magnetic forces refer to the force acting on a permanent magnet and an iron core, the force acting on a permanent magnet and an electric current, the force acting on an iron core and an electric current, etc.

[0012] A two-axis controlled magnetic bearing or bearingless motor detects the position of the rotor only in the radial direction with a sensor, and adjusts the radial support force so that the detected position matches the target position. In other words, a two-axis controlled magnetic bearing or bearingless motor actively controls only the radial direction. The radial direction is the x-axis direction and the y-axis direction when the rotation axis is the z-axis. To generate a support force, a bias current is generally passed through each winding, or a permanent magnet is placed on the magnetic circuit instead of the bias current, in addition to passing a fluctuating current that contributes to increasing or decreasing the support force through the winding. The following principle is valid for either method, but the following explanation will be given for the case where a permanent magnet is used.

[0013] Two-axis controlled magnetic bearings or bearingless motors generally have a passive and stable structure without active control of the rotor's axial direction and tilt direction. Here, the axial direction is the z-axis direction, and the tilt directions are θx and θy. Hereinafter, the controlled direction is called the controlled direction. On the other hand, the direction that is not controlled and is passively stable is called the passively stable direction.

[0014] In electromagnetic rotating machines such as magnetic bearings or bearingless motors, the rotor may be equipped with a permanent magnet and the stator with an iron core, or the rotor may be equipped with an iron core and the stator with a permanent magnet. For simplicity's sake, the following description will focus on the former case.

[0015] Here, we will explain permeance. Permeance, also called magnetic permeance, means the ease with which magnetic flux passes. If permeance is P, magnetic permeability is μ, magnetic path length is l, and magnetic path cross-sectional area is S, then P=μS / l holds. In other words, 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. 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. The quantity that means the difficulty with which magnetic flux passes, which is the reciprocal of permeance P, is called magnetic resistance or reluctance. Therefore, making permeance P smaller in one direction from one end to the other end in the axial direction is synonymous with making reluctance larger in one direction from one end to the other end in the axial direction.

[0016] To achieve passive stability, the attractive force between the rotor's permanent magnet and the stator's iron core is utilized. For example, when the rotor is displaced in the axial direction, magnetic flux flows between the rotor's permanent magnet and the stator's iron core, which are separated by a radial gap, generating an attractive force between them, which acts to return the axial displacement of the rotor to its original position. As a result, a restoring force is generated in the opposite direction to the axial displacement without control. The attractive force acting between the permanent magnet and the iron core is proportional to the distance, so it can be thought of as a spring force. Hereinafter, this force acting in the axial direction is called the axial restoring force fz. The ratio of the axial restoring force fz to the axial displacement Δz is called the restoring force coefficient kz. In the following, the axial force generated in each region of the gap is referred to as the axial restoring force f 1Z , axial restoring force f 2Z The total axial restoring force fz acting on the rotor is the sum of these axial restoring forces f 1Z , axial restoring force f 2Z It becomes the sum of etc.

[0017] In this way, an axial restoring force fz is generated between the rotor and the stator, but if the value of the axial restoring force fz is small, problems such as a decrease in the stability of magnetic levitation, a decrease in the area that generates the support force and torque between the stator and the rotor due to an increase in axial displacement, and the rotor slipping out of the stator occur. This problem becomes more pronounced when the axial length of the rotor is short. In other words, even if the rotor is slightly displaced in the axial direction, 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 a slight axial displacement of the rotor can cause the ratio of the generated torque and support force to decrease more than it should. In the case of a two-axis control type, the axial length of the rotor is often designed to be smaller than the radius of the rotor. Therefore, it is inevitable that the entire device will be flattened and the axial length of the rotor will be relatively small.

[0018] Embodiment 1 FIG. 1 is a bottom view showing the configuration of a bearingless motor 1 as an electromagnetic rotating machine according to the first embodiment. In FIG. 1, the z direction corresponds to the vertical direction (up-down direction), and the xy plane is perpendicular to the z axis. In FIG. 1, the xy plane of the bearingless motor 1 is viewed from below. The bearingless motor 1 includes a stator 10 and a rotor 20. The stator 10 includes a stator core 11 and a winding (not shown). The stator core 11 includes a back yoke portion 12 that forms an outer circumferential magnetic path, and a plurality of teeth portions 13. The plurality of teeth portions 13 protrude inward from the back yoke portion 12. Each of the teeth portions 13 includes a teeth main body portion 13a and a plurality of brim-shaped teeth tip portions 13b protruding from the tip of the teeth main body portion 13a on both sides in the circumferential direction. The teeth tip portions 13b include an upper-stage teeth tip portion 13b1 and a lower-stage teeth tip portion 13b2, the details of which will be described later. Stator core 11 may be a thick bulk body of a ferromagnetic material such as iron, may be a laminated steel plate in which a plurality of steel plates are laminated, or may be a powdered iron core.

[0019] The rotor 20 includes a rotor core 21 and a plurality of permanent magnets 22. The rotor 20 is disposed inside the stator 10 via the gap portion 2. For convenience, the windings are not illustrated, but the windings may be of two types, a support winding for floating the stator 10 and a motor winding for generating torque, or only a support winding. Only one type of winding may be prepared, and the sum of a current for generating a support force and a current for generating torque may be passed through this winding. Due to the presence of the permanent magnets 22, a bias magnetic flux passes between the stator 10 and the rotor 20 in the gap portion 2 even without passing a bias current through the winding. Furthermore, due to the presence of the permanent magnets 22, a magnet torque for rotating the rotor 20 can be generated, and the rotor 20 can function as a bearingless motor. The rotor core 21 may be a thick bulk body of a ferromagnetic material such as iron, a laminated steel plate in which a plurality of steel plates are laminated, or a powdered iron core may be used.

[0020] FIG. 2 is a bottom view showing the configuration of the magnetic bearing 3 as the electromagnetic rotating machine of the first embodiment. In FIG. 2, the xy plane of the magnetic bearing 3 is seen from below. FIG. 3 is a cross-sectional view showing the configuration of the magnetic bearing 3 as the electromagnetic rotating machine of the first embodiment. FIG. 3 cuts FIG. 2 in the xz plane. In the magnetic bearing 3, the rotor 20 has only a rotor core 21, and no permanent magnet 22 is present. The configuration of the stator 10 is the same as that of FIG. 1. Although the windings 14 are not shown in FIG. 2, the windings 14 are shown in FIG. 3.

[0021] The magnetic bearing 3 includes a stator 10 and a rotor 20. The stator 10 includes a stator core 11 and a winding 14. The stator core 11 includes a back yoke portion 12 that forms an outer peripheral magnetic path, and a plurality of teeth portions 13. The teeth portions 13 protrude inward from the back yoke portion 12. Each of the teeth portions 13 includes a teeth main body portion 13a and a plurality of brim-shaped teeth tip portions 13b that protrude from the tip of the teeth main body portion 13a on both sides in the circumferential direction. The teeth tip portions 13b include upper-stage teeth tip portions 13b1 and lower-stage teeth tip portions 13b2, the details of which will be described later.

[0022] The rotor 20 includes a rotor core 21. The rotor 20 is disposed inside the stator 10 via the gap portion 2. In this case, since the magnetic bearing 3 does not include a permanent magnet in the rotor 20, it is necessary to pass a bias current through the windings 14. However, it is possible to make the bias current unnecessary by providing a permanent magnet in the rotor 20 or the stator 10. The configuration in FIG. 2 has the advantage that no copper loss resulting from the bias current occurs.

[0023] Next, the principle of generating radial support force of the magnetic bearing 3 will be described with reference to FIG. 3. In FIG. 3, the surfaces of the upper teeth tip 13b1 and the lower teeth tip 13b2 facing the rotor core 21 are actually flush, but are stepped to make the upper and lower stages easier to see. Here, a case where support force is generated in the x direction will be described. A winding 14 is wound around the teeth main body 13a on the x-axis positive side (right side), and a winding 14 is wound around the teeth main body 13a on the x-axis negative side (left side). I+i, which is the sum of the bias current I and the fluctuating current i, is passed through the winding 14 on the x-axis positive side (right side), and Ii, which is the difference between the bias current I and the fluctuating current i, is passed through the winding 14 on the x-axis negative side (left side). At this time, the magnetic flux density can be increased or decreased in the gap portion 2. In addition, considering that the current is proportional to the magnetic flux density and that the force is proportional to the square of the magnetic flux density, if the constant is k, the force acting on the surface of the gap 2 on the positive side of the x-axis (right side) is k(I+i). 2 The force acting on the surface of the gap 2 on the negative side (left side) of the X-axis is k(Ii). 2 The difference between these forces is (4×k×I×i). Therefore, rotor 20 is subjected to a force of (4×k×I×i) in the positive direction of the x-axis. In other words, by flowing bias current I and then adjusting the fluctuating current i flowing through each tooth portion 13, it is possible to generate a radial force proportional to the fluctuating current i. If it is desired to generate a supporting force in the y-axis direction as well, it is sufficient to similarly adjust the fluctuating current i flowing through another winding. As a result, it can function as a magnetic bearing that generates a supporting force in the radial direction.

[0024] Fig. 4 is a perspective view showing a partial configuration of the stator core 11 of the electromagnetic rotating machine of the first embodiment. The stator core 11 shown in Fig. 4 shows an enlarged partial configuration of the stator core 11 of the bearingless motor 1 shown in Fig. 1. The stator core 11 shown in Fig. 4 also shows an enlarged partial configuration of the stator core 11 of the magnetic bearing 3 shown in Figs. 2 and 3. A winding (not shown) is wound around the teeth main body 13a of the teeth portion 13 and current is applied to generate a radial electromagnetic supporting force in the rotor 20, thereby generating torque to rotate the rotor 20.

[0025] As shown in FIG. 4, teeth tip portion 13b has a flanged structure that widens the circumferential width so that more magnetic flux can pass between gap portion 2 and rotor 20. In the first embodiment, the width of teeth tip portion 13b is divided into two types in the up-down direction. That is, teeth tip portion 13b has upper stage teeth tip portion 13b1 as the first teeth tip portion on the axial positive side (z-direction positive side) and lower stage teeth tip portion 13b2 as the second teeth tip portion on the axial negative side (z-direction negative side). In other words, teeth portion 13 has first teeth portion as the upper stage teeth portion having upper stage teeth tip portion 13b1 as the first teeth tip portion, and second teeth portion as the lower stage teeth portion having lower stage teeth tip portion 13b2 as the second teeth tip portion. In other words, the stator core 11 includes an upper stage stator core 11-1 having upper stage teeth tip portions 13b1 and a lower stage stator core 11-2 having lower stage teeth tip portions 13b2.

[0026] The width W1 of the upper teeth tip portion 13b1 is larger than the width W2 of the lower teeth tip portion 13b2. That is, in the first embodiment, the width dimension of the teeth tip portion 13b is narrowed in one direction from one axial end side where the upper teeth tip portion 13b1 exists to the other axial end side where the lower teeth tip portion 13b2 exists. As a result, the magnetic path cross-sectional area S2 of the lower teeth tip portion 13b2 is smaller than the magnetic path cross-sectional area S1 of the upper teeth tip portion 13b1 per unit axial length. In FIG. 4, two layers of the laminated structure correspond to the unit axial length. The hatched magnetic path cross-sectional area S1 corresponds to the area per unit axial length of the portion of the upper teeth tip portion 13b1 facing the rotor 20. The hatched magnetic path cross-sectional area S2 corresponds to the area per unit axial length of the portion of the lower teeth tip portion 13b2 facing the rotor 20.

[0027] That is, the permeance P of the magnetic flux passing through the lower stage teeth is smaller than the permeance P of the magnetic flux passing through the upper stage teeth. In this structure, the gap surface between the stator 10 and the rotor 20 is not tapered as in Patent Document 1, so that the rotor 20 does not come into contact with the stator 10 even if it moves in the axial direction. In addition to the upper stage teeth tip 13b1 and the lower stage teeth tip 13b2, other teeth tips may be provided so as to satisfy the condition that the circumferential width of the teeth tip 13b, which is the tip of the teeth 13, becomes smaller in one direction from one end side to the other end side in the axial direction. For example, a middle stage teeth tip may be provided between the upper stage teeth tip 13b1 and the lower stage teeth tip 13b2, the middle stage teeth tip having a circumferential width shorter than the upper stage teeth tip 13b1 and a circumferential width longer than the lower stage teeth tip 13b2. Furthermore, a teeth tip portion having a smaller circumferential width than lower row teeth tip portion 13b2 may be provided on the axially negative side of lower row teeth tip portion 13b2, as will be described later with reference to FIG.

[0028] The magnetic path and permeance P in the upper stator core 11-1 will be described with reference to FIG. 5. FIG. 5 is an xy cross-sectional view showing the configuration of the upper stator core 11-1 of the electromagnetic rotating machine according to the first embodiment. As shown in FIG. 5, a circular magnetic path J is formed that circulates around the stator 10 and the rotor 20 via the gap 2. The circular magnetic path J can be mainly divided into two directions, a radial direction and a circumferential direction. The circular magnetic path J has teeth tip permeance P1, gap permeance P2, rotor permeance P3, teeth main body permeance P4, and back yoke permeance P5. When the width W1 of the upper teeth tip 13b1 is increased, the cross-sectional area of ​​the magnetic path passing through the upper teeth tip 13b1 increases, and the permeance P of the teeth tip 13b increases.

[0029] The magnetic path and permeance P in the lower stator core 11-2 will be described with reference to FIG. 6. FIG. 6 is an xy cross-sectional view showing the configuration of the lower stator core 11-2 of the electromagnetic rotating machine of the first embodiment. In the lower stator core 11-2, the circular magnetic path J also has teeth tip permeance P1, gap permeance P2, rotor permeance P3, teeth main body permeance P4, and back yoke permeance P5. As described above, the width W2 of the lower teeth tip 13b2 is smaller than the width W1 of the upper teeth tip 13b1. As a result, the cross-sectional area of ​​the magnetic path passing through the lower teeth tip 13b2 becomes smaller, and the permeance P of the teeth tip 13b decreases.

[0030] FIG. 7 is a perspective view showing a partial configuration of the stator 10 and rotor 20 of the electromagnetic rotating machine of the first embodiment, showing a state in which the rotor 20 is displaced in the axial direction by Δz. FIG. 8 is a perspective view showing a partial configuration of the stator 10 and rotor 20 of the electromagnetic rotating machine of the first embodiment, showing a state in which the rotor 20 is not displaced in the axial direction. The principle of increase in axial restoring force when the tooth tip portion 13b has a two-stage structure of an upper stage and a lower stage will be explained using FIG. 7 and FIG. 8. The stator 10 and rotor 20 are shown as models cut in the xz plane. For simplicity, lines showing the laminated structure are not drawn.

[0031] When this electromagnetic rotating machine is used as a fan, blower, pump, or the like, the rotor 20 is subjected to a reaction force when gas or liquid is sent out from the blades attached to the rotor 20. In addition, regardless of the presence or absence of blades, the rotor 20 is subjected to gravity mg due to the mass of the rotor 20 itself. In Figs. 7 and 8, the rotating shaft is arranged vertically, and the gravity mg of the rotor 20 acts in the axial direction. The vertical upward direction is defined as the positive direction of the z axis. At this time, the rotor 20 tries to move vertically downward, that is, in the negative direction of the z axis, due to forces such as gravity mg. However, as described above, when the rotor 20 is displaced in the axial direction, an axial restoring force fz is generated in the direction opposite to the displacement. Therefore, the rotor 20 floats to a position where these forces are balanced. Since part of the magnetic flux is concentrated at the lower end 13c1 of the teeth portion 13, the axial restoring force f 1Z This axial restoring force f 1Z This occurs even in a general shape in which the width dimension of the tooth tip portion 13b is not changed.

[0032] On the other hand, in the first embodiment, the width W1 of the tip portion 13b1 of the upper teeth is made larger than the width W2 of the tip portion 13b2 of the lower teeth, so that at the underside of the tip portion 13b1 of the upper teeth, in other words, at the intermediate portion 13c2 in the vertical direction of the teeth portion 13, the flange portion of the tip portion 13b1 of the upper teeth protrudes further in the circumferential direction than the flange portion of the tip portion 13b2 of the lower teeth, and magnetic flux is concentrated here as well. This is because there is a difference in permeance P between the upper teeth portion and the lower teeth portion. In other words, this is because the permeance P is made smaller in one direction from one end side to the other end side in the axial direction. Therefore, a new axial restoring force f is also generated in the intermediate portion 13c2 in the vertical direction of the teeth portion 13. 2Z In this way, by forming the teeth tip portions 13b into a two-stage structure with an upper stage and a lower stage, the axial restoring force fz increases in one direction.

[0033] As shown in FIG. 8, when the rotor 20 is not displaced in the axial direction, the axial restoring force f 1ZHowever, the axial restoring force f generated by forming the teeth tip portion 13b into a two-stage structure with an upper stage and a lower stage is 2Z These are described by the formula. The resultant force acting on the rotor 20 in the axial direction is F Z Then, the resultant force F Z is the gravity mg, the disturbance d caused by the reaction force mentioned above, and the axial restoring force f 1Z and the axial restoring force f 2Z The equation of motion in the axial direction is given by F Z =-mg+d+f 1Z +f 2Z

[0034] Axial restoring force f 1Z is proportional to the axial displacement Δz. If the axial restoring force coefficient is kz, then f 1Z =-kz·Δz. The negative sign means that the rotor 20 is attracted to the stator 10 in the direction opposite to the direction of displacement. The axial restoring force f 2Z is due to the magnetic flux between the stator 10 and the rotor 20 at the intermediate portion 13c2, but since this has almost no relation to the axial displacement Δz of the rotor 20, it can be regarded as a constant. 2Z >0. Therefore, the equation of motion in the axial direction is as follows: F Z =-mg+d-kz Δz+f 2Z The balance position is F Z = 0. This can be expressed as follows: Δz=(-mg+d+f 2Z ) / kz

[0035] Axial restoring force f 2Z When the width of the teeth tip portion 13b is constant and Δz is 0, Δz=(-mg+d) / kz, and the position of balance shifts in the axial direction by the amount of gravity mg and disturbance d. However, as in the first embodiment, 2Z >0, the equilibrium position approaches Δz=0. Axial restoring force f2Z This balances the sum of the gravity mg of the rotor 20 and the disturbance d, resulting in f 2Z If Δz=mg-d, the rotor 20 can continue to be levitated at the position of Δz=0. Hereinafter, for simplicity, it is considered that the disturbance is d=0.

[0036] 9 is a graph showing the relationship between axial displacement and axial restoring force in the electromagnetic rotating machine of the first embodiment and a comparative example. In FIG. 9, the horizontal axis represents axial displacement Δz, and the rotor 20 is displaced to the negative axial side from the origin as it moves to the right of the horizontal axis. The vertical axis represents axial restoring force fz, and the axial restoring force f 1Z and axial restoring force f 2Z and the sum of these. In Fig. 9, the vertical and horizontal axes are shown as normalized values. The thick solid line corresponds to the case where teeth tip portions 13b have a two-tier structure with an upper tier and a lower tier, as shown in the first embodiment. The dashed line corresponds to the comparative example, where the width of teeth tip portions 13b is constant. Fig. 9 shows the results of an analysis of the relationship between axial displacement and axial restoring force using the finite element method.

[0037] It can be seen that in both the one-stage structure (comparative example) and the two-stage structure (embodiment 1), the axial restoring force increases as the axial displacement increases. This is because the axial restoring force f 1Z The influence of the two-stage structure (embodiment 1) is such that the two-stage structure is offset from the one-stage structure (comparative example) by a certain amount. This increase is the axial restoring force f 2Z This corresponds to the influence of gravity. The position of balance with gravity can be found by drawing a horizontal line and calculating the point where gravity and the axial restoring force overlap. Q1 is the position of balance in the comparative example, and Q2 is the position of balance in the first embodiment. This analysis result shows that the position of balance is closer to the origin in the first embodiment than in the comparative example.

[0038] Fig. 10 is a perspective view showing a partial configuration 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 in which the width dimension of the tooth tip portion 13b is changed may be three or more stages instead of two stages. In Fig. 10, the tooth tip portion 13b has an upper stage tooth tip portion 13b1, a middle stage tooth tip portion 13b3, and a lower stage tooth tip portion 13b2, and the relationship of the width W1 of the upper stage tooth tip portion 13b1>the width W3 of the middle stage tooth tip portion 13b3>the width W2 of the lower stage tooth tip portion 13b2 is satisfied. In addition, the width dimensions of the tooth tips of all the laminated steel plates may be changed to change the width dimensions linearly instead of stepwise.

[0039] Furthermore, although 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 above, the first embodiment may 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, the same effect as described above can be obtained by changing the width dimension of the teeth tip portions 13b of the outer rotor type stator 10 in one direction, the z direction, in multiple steps or linearly.

[0040] Furthermore, although the above describes a case where rotor 20 is equipped with a permanent magnet and stator 10 is equipped with an iron core, embodiment 1 may also be applied to a case where rotor 20 is equipped with an iron core and stator 10 is equipped with a permanent magnet. In this case, the same effect as described above can be obtained by changing the width dimension of the tooth tips of the teeth portion of an inner rotor type or outer rotor type rotor in one direction, the z direction, in multiple steps or linearly.

[0041] In the above, the gravity mg of the rotor 20 is assumed, and the axial restoring force f is applied in the opposite direction to the gravity mg of the rotor 20. 2ZIn the above, the case where the teeth tips 13b are made to have a multi-stage structure so that the axial restoring force mg occurs has been described, but it is also possible to deal with forces other than gravity mg. For example, a pump that circulates liquid by attaching blades to the rotor 20 also generates an axial reaction. Since the direction of this reaction force is predetermined to one direction, it is sufficient to shorten the width dimension of the teeth tips 13b in one direction so that the axial restoring force increases in the opposite direction to the direction of this reaction.

[0042] 1 shows a surface magnet type in which permanent magnets 22 are arranged on the surface of rotor 20, but embodiment 1 may also be applied to an embedded magnet type in which permanent magnets 22 are arranged inside the core of rotor 20. Moreover, embodiment 1 may also be applied to a motor in which permanent magnets 22 are not arranged on the rotor 20 side and which utilizes reluctance torque.

[0043] In addition, it is preferable to design the rotor 20 so that the axial length (length in the axial direction) is shorter than the radial length of the rotor 20. In this way, the restoring force coefficient kz and the axial restoring force f 1Z In addition, the axial restoring force f 2Z The effect of is also added, and the position of equilibrium approaches the origin.

[0044] FIG. 11 is a development view showing a configuration of a modified example of the electromagnetic rotating machine of the first embodiment. In FIG. 11, the sensor 16 is arranged in the region 15 between the tips 13b2 of the lower teeth adjacent to each other. The region 15 between the tips 13b2 of the lower teeth adjacent to each other has a wider slot opening width, so that a space for arranging various components can be secured. In the region 15, a base or a holding mechanism for the sensor 16, wiring for the sensor 16, a crossover wire for the winding, or a refrigerant pipe for cooling may be arranged. In addition, the sensor 16 for detecting the ambient temperature, the magnetic flux density, or the distance from the rotor 20 may be arranged. The sensor 16 may be a Hall element, a thermocouple, or an eddy current displacement sensor. In this case, 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 to the lower side where the slot opening width is wider. This is because if the flange of the teeth 13 protrudes too much, magnetic flux flows through the flange, reducing the sensitivity of the sensor 16, but this phenomenon can be suppressed by widening the slot opening width on the lower tier side. When three or more tiers of teeth tips are provided as shown in Fig. 10, it is difficult to place the sensor 16 on the upper tier teeth tip 13b1 side from the perspective of space, but the same effect can be obtained by placing the sensor 16 on the middle tier teeth tip 13b3 side or the lower tier teeth tip 13b2 side. In this case, the above-mentioned effect can be obtained most effectively by placing the sensor 16 on the lower tier teeth tip 13b2 side, which has the widest slot opening width.

[0045] Thus, according to the first embodiment, the permeance P, which is a quantity representing the ease of passage of magnetic flux in at least one of the gap portion and the iron core in the circular magnetic path J that circles the stator 10 and the rotor 20 in the radial and circumferential directions, is made to decrease in one direction from one end side in the axial direction to the other end side, and specifically, the width dimension of the teeth tip portion 13b of the teeth portion 13 is changed in one direction in the z direction in multiple steps or linearly. Therefore, it is not necessary to make the gap surface between the stator 10 and the rotor 20 tapered, and the axial restoring force of the rotor 20 can be increased in one direction without deteriorating the assembly and disassembly. In addition, since the clearance of the gap between the rotor 20 and the stator 10 can be kept small, the magnetic flux can easily pass 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 the amount of heat generated and an increase in efficiency can be obtained.

[0046] Furthermore, according to the first embodiment, even if the rotor 20 is not displaced in the axial direction, the axial restoring force f 2Z As shown in FIG. 8, when the rotor 20 is not displaced in the axial direction, the gravity mg of the rotor 20 and the axial restoring force f 2Z When the two are balanced, all axial regions of the stator 10 and the rotor 20 face each other. Therefore, the supporting force and torque generated when the same current flows between the stator 10 and the rotor 20 increases. As a result, the copper loss when the same supporting force and torque are generated can be reduced.

[0047] Furthermore, according to the first embodiment, only the width of the tooth tips 13b is changed, and the inner diameter of the stator 10 and the outer diameter of the rotor 20 are not changed, so the range of motion of the rotor 20 is not reduced at all. In other words, if the inner diameter of the stator 10 or the outer diameter of the rotor 20 is changed, when the rotor 20 is displaced in the radial direction, axial direction, or tilt direction, the rotor 20 and the stator 10 come into contact with each other at the protruding parts or at the parts where the gap is narrowed, causing a problem of reduced range of motion of the rotor 20. According to the first embodiment, it is possible to increase the axial force generated in the rotor 20 without causing this disadvantage.

[0048] Embodiment 2 FIG. 12 is a perspective view showing a part of a stator core 11 of an electromagnetic rotating machine according to a second embodiment. In FIG. 12, the direction of the z-axis is inverted by 180 degrees from that of FIGS. 1 to 4 to improve visibility, and a perspective view is shown as seen from below. In the second embodiment, the teeth main body portion 13a also has a step configuration of two or more stages, and the circumferential width W4 of the upper stage teeth main body portion 13a1 as the first teeth main body portion is larger than the circumferential width W5 of the lower stage teeth main body portion 13a2 as the second teeth main body portion. In addition, the back yoke portion 12 also has a step configuration of two or more stages, and the radial width W6 of the upper stage back yoke portion 12-1 as the first back yoke portion is larger than the width W7 of the lower stage back yoke portion 12-2 as the second back yoke portion.

[0049] Therefore, the cross-sectional area of ​​the magnetic path is smaller in the lower stage than in the upper stage, and the permeance P is smaller. Therefore, the magnetic flux passes more easily between the upper stage of the stator 10 and the rotor 20 than between the lower stage of the stator 10 and the rotor 20, and the axial magnetic flux and the axial restoring force f 2Z Therefore, when the structure of the second embodiment is adopted in addition to changing the width dimension of the tooth tip portion 13b, the axial restoring force f 2Z In addition, shortening the width dimensions of teeth main body portion 13a and back yoke portion 12 leads to a reduction in the weight of the entire device.

[0050] In addition, FIG. 12 shows a case where the width dimensions of both the teeth main body portion 13a and the back yoke portion 12 are changed, but the width dimension of only one of them may be changed. In addition, although not shown in FIG. 12, when winding the winding around the teeth portion 13, the width dimension of the lower stage is shortened, so that the circumferential length of the winding can be shortened. Therefore, the resistance and copper loss can be reduced. In addition, the angle when winding the winding on the lower stage is larger than 90 degrees, so that the winding bulge is suppressed. As a result, the area of ​​the winding end portion can be reduced, and in addition to the above-mentioned reduction in copper loss, the size and weight of the entire device can be reduced. In addition, by making the width of the teeth tip portion 13b different, the effect described in the first embodiment can be obtained. However, it is not necessary to make the width of the teeth tip portion 13b different.

[0051] In addition, the width W5 of the lower teeth main body 13a2 is shortened and the winding bulge is suppressed, so that the slot space between them can be secured. As a result, as in the first embodiment, the sensor 16 and other holding mechanisms can be placed at this position. Also, in the case where the sensor 16 is long in the radial direction and needs to be placed across both the tooth tip portions 13b and the tooth main body portions 13a, the area for the sensor 16 can be secured over the entire length.

[0052] Thus, according to the second embodiment, in order to reduce permeance P in one direction from one axial end to the other, circumferential width W4 of upper stage teeth main body portion 13a1 is made larger than circumferential width W5 of lower stage teeth main body portion 13a2, and radial width W6 of upper stage back yoke portion 12-1 is made larger than width W7 of lower stage back yoke portion 12-2. Therefore, the axial restoring force of rotor 20 can be increased in one direction without compromising ease of assembly and disassembly, and the position of sensor 16 can be secured.

[0053] Embodiment 3 Fig. 13 is a perspective view showing a partial configuration of a stator core 11 of an electromagnetic rotating machine according to embodiment 3. Fig. 14 is a perspective view showing a partial configuration of a modified example of the stator core 11 of the electromagnetic rotating machine according to embodiment 3. As with Fig. 12, Figs. 13 and 14 also show perspective views of the stator core 11 as seen from below. For simplification, lines showing the laminated structure are not drawn.

[0054] In FIG. 13, grooves 17 are provided on the gap surface of lower-stage teeth tips 13b2 that faces rotor 20. Groove 17 is also called a dummy slot because it is a slot portion without a winding. In FIG. 11, groove 17 is provided only on the lower stage, so an upper-stage exposed surface 17a is formed on the upper stage side of groove 17, where part of upper-stage teeth tips 13b1 are exposed. With this configuration, magnetic flux is generated that passes obliquely between upper-stage exposed surface 17a of upper-stage teeth tips 13b1 and rotor 20, resulting in an axial restoring force f 2Z This can be considered as a result of groove 17 making it difficult for magnetic flux to pass through a portion of tip portion 13b2 of the lower row of teeth, resulting in a decrease in permeance P.

[0055] In Fig. 14, groove portion 17 is provided as the second groove portion on the gap surface of tip portion 13b2 of the lower teeth, and groove portion 18 is provided as the first groove portion on the gap surface of tip portion 13b1 of the upper teeth. The dimension of groove portion 17 is made larger than the dimension of groove portion 18. The dimension of groove portion 17 refers to width dimension L1 or depth dimension L2, and both may be changed, or only one of the dimensions may be changed. In this way, upper exposed surface 17a can be generated, similar to Fig. 13.

[0056] Thus, according to the third embodiment, in order to reduce the permeance P in one direction from one end side to the other end side in the axial direction, the groove 17 is provided on the gap surface of the lower teeth tip 13b2, so that not only the effect of increasing the axial restoring force but also the waveform or peak value of the cogging torque generated between the stator 10 and the rotor 20 can be adjusted even when no current is applied. Normally, it is desirable to have a small cogging torque, but the effect of reducing the cogging torque can be obtained at the same time. In addition, by making a difference in the width of the teeth tip 13b or the width of the teeth main body 13a, the effects described in the first and second embodiments can be obtained. However, the effect of increasing the axial restoring force in one direction can be obtained just by devising the groove 17.

[0057] Embodiment 4 FIG. 15 is a perspective view showing a partial configuration of the stator core 11 of the electromagnetic rotating machine of the fourth embodiment. In the fourth embodiment, the material of the core is different between the upper stator core 11-1 and the lower stator core 11-2. 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, and the magnetic flux density of the upper stator core 11-1 is higher than that of the lower stator core 11-2. The upper stator core 11-1 has an upper tooth tip portion 13b1, and the lower stator core 11-2 has a lower tooth tip portion 13b2, and the width of the upper tooth tip portion 13b1 is larger than the width of the lower tooth tip portion 13b2. The high magnetic flux density material refers to, for example, a material having a high magnetic flux density for the same magnetic field strength. For example, oriented electromagnetic steel sheets may be used for the upper stator core 11-1, and non-oriented electromagnetic steel sheets may be used for the lower stator core 11-2. In addition, the characteristics of the magnetic flux density with respect to the magnetic field strength of the entire region may be changed by changing the space factor of the laminated steel sheets. This means that the space factor of the upper stator core 11-1 is set to 96% and the space factor of the lower stator core 11-2 is set to 92%, for example, and the magnetic characteristics of the entire region can be changed even if the laminated steel sheets are made of the same material. This change can also be said to change the magnetic permeability. As described above, the permeance P is also a function of the magnetic permeability, so that the permeance P can be changed in the axial direction as a result.

[0058] Thus, according to the fourth embodiment, in order to reduce the permeance 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 larger than that of the lower stator core 11-2, so that the magnetic flux is 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 generated between the rotor 20 and the stator 10 2Z It is preferable to apply the shape improvements described in the first to third embodiments, but the same effect can be obtained simply by changing the material.

[0059] Embodiment 5. FIG. 16 is a perspective view showing a partial configuration of a stator and a rotor of an electromagnetic rotating machine according to a fifth embodiment. FIG. 17 is an xz cross-sectional view showing the configuration of an electromagnetic rotating machine according to a fifth embodiment. FIG. 16 shows a perspective view seen from the axial lower part for visibility. In the fifth embodiment, the inner diameter of the stator core 11 or the gap length between the stator 10 and the rotor 20 is changed so as to become shorter in one direction from one end side to the other end side in the axial direction in multiple steps or in a straight line. From another perspective, this can also be said to be changed so as to become longer in one direction from one end side to the other end side in the axial direction in multiple steps or in a straight line. Specifically, the inner diameter D3 of the upper stator core 11-1 and the inner diameter D2 of the lower stator core 11-2 are made different, and the inner diameter D3 of the upper stator core 11-1 is made 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 teeth tip portion 13b. If the upper teeth of the teeth portion 13 are referred to as the first teeth portion and the lower teeth of the teeth portion 13 are referred to as the second teeth portion, it can be considered that the first teeth portion having the first teeth tip portion and the second teeth portion having the second teeth tip portion having a larger inner diameter than the first teeth tip portion are arranged in the axial direction. It is preferable that the gap in the second teeth portion is wider than the gap in the first teeth portion, and that the second teeth portion is arranged so as to be vertically downward. Note that expressing the gap length as long or short is synonymous with expressing the gap as wide or narrow.

[0060] In Embodiment 5, in the upper stator core 11-1, the intermediate portion 13c2 that protrudes and is visible from 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 passing between the rotor 20 and the stator 10 obliquely passes through this 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. Also, in Embodiment 5, as shown in Embodiment 1, the width of the upper tooth tip portion 13b1 is made 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 between the upper and lower parts, the axial force generated in the rotor 20 can be further increased. However, even if only the inner diameter of the stator core 11-2 is changed between the upper and lower parts without changing the width of the tooth tip portion 13b between the upper and lower parts, the same effect as in Embodiment 1 can be obtained.

[0061] In Embodiment 5, the inner diameter of the stator core 11 is set to D3 < D2. Also, when the outer diameter of the rotor 20 is D1, D1 < D3 is satisfied. As a result, even if the rotor 20 is moved axially, the rotor 20 does not contact the stator 10. As a result, the assembly and disassembly property is not deteriorated. Also, in Patent Document 1, both the inner diameter of the stator 10 and the outer diameter of the rotor 20 were changed. For this, it is necessary to prepare a plurality of shapes for both the stator 10 and the rotor 20, which incurs manufacturing costs. However, in Embodiment 5, since only the shape of one of the stator 10 and the rotor 20 is changed, an increase in manufacturing costs can be suppressed. In particular, manufacturing magnets with different diameters and magnets with an oblique 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. Also, 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, and there may be almost no difference in shape. For example, after creating the upper stator core 11-1 with a small inner diameter once, a part of this can be reworked to widen the inner diameter to create the lower stator core 11-2.

[0062] Also, such a structural change can also be explained in terms of the gap length. The magnetic permeability of the air gap portion 2 made of air is sufficiently smaller than that of the iron core. That is, the magnetic path length of the gap portion 2 significantly affects the permeance P. Let the gap length of the upper stator core 11-1 be G1 and the gap length of the lower stator core 11-2 be 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 long in the lower stator core 11-2. Therefore, it can be considered that the permeance P decreases in one direction from one end side to the other end side in the axial direction. In Embodiment 5, the diameter of the rotor 20 is not changed. Therefore, even if the rotor 20 moves in the axial direction, the values of G1 and G2 are constant, and the magnitude relationship does not change.

[0063] Note that in the case of an outer rotor type in which the stator 10 is arranged inside and the rotor 20 is arranged outside, changing the shape of the stator 10 according to the axial position corresponds to changing the outer diameter of the stator 10.

[0064] Thus, according to Embodiment 5, in order to decrease the permeance P in one direction from one end side to the other end side in the axial direction, the inner diameter of the stator core or the gap length between the stator 10 and the rotor 20 is changed to be shorter in a plurality of steps or linearly in one direction from one end side to the other end side in the axial direction. Therefore, without deteriorating the assembly and disassembly property, the axial restoring force of the rotor 20 can be increased in one direction. Also, the clearance of the gap between the rotor 20 and the stator 10 can be kept small, so that the 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 decrease in the amount of heat generation and an increase in efficiency can be obtained.

[0065] Embodiment 6. FIG. 18 is a diagram for explaining the principle of adjusting the axial restoring force of the electromagnetic rotating machine according to the sixth embodiment. FIG. 19 is a diagram for explaining the principle of adjusting the axial restoring force of the electromagnetic rotating machine according to the sixth embodiment. In FIG. 18 and FIG. 19, the rotor 20 is displaced in the -z direction, and the direction of the current flowing through the winding 14 is different between FIG. 18 and FIG. 19. FIG. 20 is a diagram for explaining the principle of adjusting the axial restoring force of the electromagnetic rotating machine according to the sixth embodiment. FIG. 21 is a diagram for explaining the principle of adjusting the axial restoring force of the electromagnetic rotating machine according to the sixth embodiment. In FIG. 20 and FIG. 21, the rotor 20 is not displaced, and the direction of the current flowing through the winding 14 is different between FIG. 20 and FIG. 21.

[0066] Normally, if there is no axial displacement of the rotor 20, no axial restoring force is generated in the rotor 20. However, as described above, the permeance P in the magnetic path that circles the stator 10 and the rotor 20 in the radial and circumferential directions, that is, the width dimension of the teeth tip portion 13b of the teeth portion 13, the circumferential width of the teeth main portion 13a, the inner diameter of the teeth tip portion 13b, or the material of the stator core 11, is changed in one direction, the z direction, in multiple steps or linearly, so that an axial restoring force is generated even if there is no axial displacement of the rotor 20. This is due to the bias magnetic flux generated between the rotor 20 and the stator 10 by the bias current or magnet. As described above, the axial restoring force is the axial restoring force f that is generated in proportion to the axial displacement of the rotor 20. 1Z and the axial restoring force f which occurs constantly regardless of the axial displacement 2Z Both of these can be increased or decreased by the d-axis current.

[0067] 18 to 21 show the case where the rotor 20 has a permanent magnet 22. FIG. 18 shows the case where a positive d-axis current is passed through the winding 14 so as to strengthen the magnetic flux Φ1 caused by the permanent magnet 22. At this time, the magnetic flux Φ1 caused by the permanent magnet 22, shown by the solid line, is further strengthened by the magnetic flux Φ2 caused by the winding 14, shown by the dotted line. As a result, the axial restoring force f generated in proportion to the axial displacement is 1Z and the axial restoring force f 2ZOn the other hand, in FIG. 19, the magnetic flux Φ1 by the permanent magnet 22 shown by the solid line and the magnetic flux Φ2 by the winding 14 shown by the dotted line are in the opposite direction, and they weaken each other. As a result, the axial restoring force f 1Z and the axial restoring force f 2Z and decreases.

[0068] 20 and 21 show the case where the rotor 20 is not displaced in the axial direction, z=0. In this case, the axial restoring force f 1Z is 0. However, the axial restoring force f 2Z In FIG. 20, a positive d-axis current is passed through the winding 14 to strengthen the magnetic flux Φ1, and the axial restoring force f 2Z In FIG. 21, a negative d-axis current is passed through the winding 14 to weaken the magnetic flux Φ1, and the axial restoring force f 2Z decreases.

[0069] This will be explained using a formula. Let the d-axis current be i d In addition, the axial restoring force f 1Z is (1+k Zi1 i d ) times the change. Here, k Zi1 is the axial restoring force f due to the d-axis current. 1Z The coefficient indicates the rate at which the axial restoring force f 2Z is (1+k Zi2 i d ) times the change. Here, k Zi2 is the axial restoring force f due to the d-axis current. 2Z is a coefficient that indicates the rate at which the value changes. The equation of motion in the axial direction is as follows. F Z =-mg-k Z (1+k Zi1 i d )f 1Z +(1+k Zi2 i d )f 2Z

[0070] When there is no axial displacement (z=0), the axial equation of motion is: F Z =-mg+(1+k Zi2 i d )f 2Z

[0071] Therefore, in both cases of z<0 and z=0, the d-axis current i d If a controller is provided to increase or decrease the axial resultant force F acting on the rotor 20, Z It is possible to adjust the resultant axial force F acting on the rotor 20 in the same manner when z>0. Z You can also adjust the

[0072] For stable magnetic levitation, it is important to reduce the vibration of rotor 20. To this end, a control device may be provided that detects the axial vibration of rotor 20 and increases or decreases the d-axis current flowing through winding 14 in response to the detected vibration. In other words, according to the sixth embodiment, the axial restoring force can be adjusted to reduce the axial vibration even if there is no axial displacement.

[0073] The configurations shown in the above embodiments are examples of the contents of the present disclosure, and may be combined with other known technologies, and parts of the configurations may be omitted or modified without departing from the gist of the present disclosure. [Explanation of symbols]

[0074] 1 bearingless motor, 2 gap portion, 3 magnetic bearing, 10 stator, 11, 11-1, 11-2 stator core, 12 back yoke portion, 12-1 upper back yoke portion, 12-2 lower back yoke portion, 13 teeth portion, 13a teeth main body portion, 13a1 upper teeth main body portion, 13a2 lower teeth main body portion, 13b teeth tip portion, 13b1 upper teeth tip portion, 13b2 lower teeth tip portion, 13b3 middle teeth tip portion, 13c1 lower end portion, 13c2 intermediate portion, 14 winding, 15 area, 16 sensor, 17, 18 groove 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. A rotor; a stator disposed across a gap from the rotor; and generating a supporting force for levitating the rotor in a non-contact manner by an electromagnetic force or a magnetic force, At least one of the rotor and the stator includes a plurality of teeth portions each having a plurality of stages of iron cores for winding a winding therearound; Permeance, which is a quantity representing the ease with which magnetic flux passes through at least one of the gap portion and the iron core in a magnetic path that circulates around the stator and the rotor in the radial and circumferential directions, is given by: By changing at least one of the following: the circumferential width at the tooth tip portion, which is the tip portion of the tooth portion; the circumferential width of the tooth main body portion; the radial width of the back yoke portion disposed on the outer periphery of the tooth main body portion; the circumferential width or radial length of the groove portion at the tooth tip portion; and the magnetic permeability of the tooth portion, the magnetic permeability becomes smaller in one direction from one end side to the other end side in the axial direction. Electromagnetic rotating machine.

2. The circumferential width of the tip of the tooth portion becomes smaller in one direction from one end side to the other end side in the axial direction.

2. The electromagnetic rotating machine according to claim 1 .

3. Each of the teeth portions includes a first teeth portion having a first teeth tip portion and a second teeth portion having a second teeth tip portion having a circumferential width smaller than that of the first teeth tip portion, the first teeth portion being arranged in the axial direction.

3. The electromagnetic rotating machine according to claim 2.

4. The second teeth are disposed vertically below the first teeth.

4. The electromagnetic rotating machine according to claim 3.

5. Each of the teeth portions has a first teeth portion and a second teeth portion arranged in an axial direction, a circumferential width of the second teeth main body portion of the second teeth portion is smaller than a circumferential width of the first teeth main body portion of the first teeth portion; or A radial width of the second back yoke portion arranged on the outer circumferential side of the second teeth main body portion is smaller than a radial width of the first back yoke portion arranged on the outer circumferential side of the first teeth main body portion.

2. The electromagnetic rotating machine according to claim 1 .

6. Each of the teeth portions includes a first teeth portion having a first teeth tip portion and a second teeth portion having a second teeth tip portion, the first teeth portion and the second teeth portion being arranged in the axial direction, The tip end portion of the second teeth includes a groove portion on a surface facing the stator or the rotor, The tip end of the first teeth does not have a groove on a surface facing the stator or the rotor.

2. The electromagnetic rotating machine according to claim 1 .

7. Each of the teeth portions includes a first teeth portion having a first teeth tip portion and a second teeth portion having a second teeth tip portion, the first teeth portion and the second teeth portion being arranged in the axial direction, the first teeth tip portion includes a first groove portion on a surface facing the stator or the rotor, the tip end portion of the second teeth is provided with a second groove portion on a surface facing the stator or the rotor, The second groove portion has a circumferential width or a radial length greater than the circumferential width or the radial length of the first groove portion.

2. The electromagnetic rotating machine according to claim 1 .

8. Each of the teeth portions has a first teeth portion and a second teeth portion arranged in an axial direction, The material of the iron core including the first teeth portion generates a larger magnetic flux density than the material of the iron core including the second teeth portion at the same magnetic field strength.

2. The electromagnetic rotating machine according to claim 1 .

9. A rotor, a stator disposed across a gap from the rotor; and generating a supporting force for levitating the rotor in a non-contact manner by an electromagnetic force or a magnetic force, At least one of the rotor and the stator includes a plurality of teeth portions each having a plurality of stages of iron cores for winding a winding therearound; a permeance, which is a quantity representing the ease with which magnetic flux passes through at least one of the gap portion and the iron core in a magnetic path that goes around the stator and the rotor in the radial and circumferential directions, decreases in one direction from one end side to the other end side in the axial direction, The rotor is levitated without contact by electromagnetic or magnetic force. Electromagnetic rotating machine.

10. The inner diameter of the tip of the teeth, which is the tip of the teeth, or the gap length, which is the length of the gap, becomes shorter in one direction from one end side to the other end side in the axial direction.

10. An electromagnetic rotating machine according to claim 1 , wherein the rotor is a rotor having a first end and a second end.

11. Each of the teeth portions includes a first teeth portion having a first teeth tip portion and a second teeth portion having a second teeth tip portion having an inner diameter larger than that of the first teeth tip portion, the first teeth portion and the second teeth portion being arranged in the axial direction.

11. An electromagnetic rotating machine according to claim 10.

12. A sensor is disposed between the adjacent tip portions of the second teeth.

4. The electromagnetic rotating machine according to claim 3.

13. A sensor is disposed between adjacent second teeth main body portions.

6. An electromagnetic rotating machine according to claim 5.

14. A control device is provided that adjusts a d-axis current flowing through the winding to increase or decrease the force with which the rotor is attracted to the stator in the axial direction.

14. An electromagnetic rotating machine according to claim 1, wherein the rotor is a rotor having a first end and a second end.

Images