Electromagnetic rotary machine

Abstract

A bearingless motor (1) as an electromagnetic rotary machine has a stator (10) and a rotor (20) disposed with a gap portion (2) interposed therebetween, and generates a support force for non-contact suspension of the rotor (20) by electromagnetic force or magnetic force. A stator core (11) has a back yoke portion (12) and a plurality of tooth portions (13). The tooth portion (13) has a tooth main body portion (13a) and a flange-like tooth tip portion (13b). The rotor (20) has a rotor core (21) and a plurality of permanent magnets (22). The tooth tip portion (13b) has an upper-stage tooth tip portion (13b1) and a lower-stage tooth tip portion (13b2). A quantity indicating easiness of passage of magnetic flux of at least one of the gap portion (2) and the iron core in a magnetic path in which the stator (10) and the rotor (20) are rotated in the radial direction and the circumferential direction, that is, a permeability decreases in one direction from one end side toward the other end side in the axial direction.

Description

Technical Field

[0001] This invention relates to electromagnetic rotating machinery such as magnetic bearings or bearingless motors. Background Technology

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

[0003] Patent Document 1 shows that the axial cross-sectional shape of the rotor of an inner rotor type bearingless rotary machine is set to a trapezoidal, abacus ball, drum, or spherical shape, and the axial cross-sectional shape of the stator of an outer rotor type bearingless rotary machine is set to a trapezoidal or abacus ball shape. With this structure, the axial restoring force acting between the rotor and the stator is increased.

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

[0005] In the method of Patent Document 1, the axial restoring force is increased by making the shape of the opposing surfaces of the rotor and stator, for example, conical. However, when the rotor moves axially or when the axial displacement during rotation is large, the rotor and stator will come into contact. Therefore, there are problems such as the time and workload required for assembly and disassembly, and the torque reduction caused by the widening gap between the rotor and stator.

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

[0007] To address the aforementioned problems and achieve the objective, the electromagnetic rotating machine of the present invention comprises: a rotor; and a stator disposed relative to the rotor at a gap, wherein a supporting force for suspending the rotor non-contactly is generated by electromagnetic or magnetic force. In the electromagnetic rotating machine, at least one of the rotor and the stator has multiple teeth composed of multiple iron core segments for winding the coils. The transmittance, a measure of the ease of magnetic flux passage in at least one of the gap and the iron core in the magnetic circuit that causes the stator and rotor to rotate radially and circumferentially, decreases in one direction from one end of the axial direction towards the other.

[0008] The effects of the invention

[0009] The electromagnetic rotating machinery according to the present invention has the following effect: it does not cause deterioration of assembly disintegration and can increase the axial restoring force of the rotor. Attached Figure Description

[0010] Figure 1 This is a bottom view showing the structure of the bearingless electric motor of the electromagnetic rotating machinery as described in Embodiment 1.

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

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

[0013] Figure 4 This is a perspective view showing a portion of the structure of the stator core of the electromagnetic rotating machinery according to Embodiment 1.

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

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

[0016] Figure 7 This is a perspective view showing a portion of the structure of the stator and rotor of the electromagnetic rotating machine according to Embodiment 1.

[0017] Figure 8 This is a perspective view showing a portion of the structure of the stator and rotor of the electromagnetic rotating machine according to Embodiment 1.

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

[0019] Figure 10 This is a perspective view showing a partial structure of a modified example of the stator core of the electromagnetic rotating machinery according to Embodiment 1.

[0020] Figure 11 This is a unfolded diagram showing a modified example of the electromagnetic rotating machinery according to Embodiment 1.

[0021] Figure 12 This is a perspective view showing a portion of the structure of the stator core of the electromagnetic rotating machinery according to Embodiment 2.

[0022] Figure 13 This is a perspective view showing a portion of the structure of the stator core of the electromagnetic rotating machinery according to Embodiment 3.

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

[0024] Figure 15 This is a perspective view showing a portion of the structure of the stator core of the electromagnetic rotating machinery according to Embodiment 4.

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

[0026] Figure 17 This is an xz cross-sectional view showing the structure of the electromagnetic rotating machinery in Embodiment 5.

[0027] Figure 18 This is a diagram illustrating the principle of adjusting the axial restoring force of the electromagnetic rotating machinery in Embodiment 6.

[0028] Figure 19 This is a diagram illustrating the principle of adjusting the axial restoring force of the electromagnetic rotating machinery in Embodiment 6.

[0029] Figure 20 This is a diagram illustrating the principle of adjusting the axial restoring force of the electromagnetic rotating machinery in Embodiment 6.

[0030] Figure 21 This is a diagram illustrating the principle of adjusting the axial restoring force of the electromagnetic rotating machinery in Embodiment 6. Detailed Implementation

[0031] The electromagnetic rotating machinery according to the embodiments will now be described in detail based on the accompanying drawings.

[0032] Rotary motors used in industrial and automotive applications typically employ bearings, such as rolling bearings, to support the rotating shaft. Because these bearings are in mechanical contact with the rotating shaft and stator, they are susceptible to wear and tear, which can lead to failure. In recent years, electromagnetic rotating machinery, such as magnetic bearings or bearingless motors, has been developed that eliminate mechanical contact. Magnetic bearings generate a supporting force through electromagnetic or magnetic forces to levitate the rotor without contact. Bearingless motors function as both a torque-generating motor and a magnetic bearing generating the aforementioned supporting force within a single magnetic circuit. To levitate the rotor of a magnetic bearing or bearingless motor, it is necessary to actively control all five degrees of freedom (excluding rotation about the rotating shaft) or passively establish a stable configuration without actively controlling only a portion of the five degrees of freedom. Furthermore, the aforementioned electromagnetic or magnetic forces refer to forces acting on a permanent magnet and an iron core, forces acting on a permanent magnet and an electric current, and forces acting on an iron core and an electric current.

[0033] Two-axis controlled magnetic bearing or bearingless motors detect position only in the radial direction of the rotor using sensors, and adjust the radial support force to ensure the detected position matches the target position. In other words, two-axis controlled magnetic bearing or bearingless motors perform active control only in the radial direction. Radial direction, when the rotation axis is set as the z-axis, includes the x-axis and y-axis directions. When generating the support force, typically, a bias current flows through each winding, contributing to the increase or decrease in support force, or a permanent magnet is placed in the magnetic circuit instead of the bias current. The following principle applies regardless of the method, but the following explanation focuses on the case where permanent magnets are used.

[0034] Two-axis controlled magnetic bearing or bearingless motors typically do not undergo active control in the rotor's rotational and tilting directions; instead, they possess a passively stable structure. Here, the axial direction is the z-axis, and the tilting directions are θx and θy. The direction to be controlled will be referred to as the control direction. Conversely, the direction that becomes stable passively without control is called the passively stable direction.

[0035] In electromagnetic rotating machinery such as magnetic bearings or bearingless motors, sometimes there is a permanent magnet in the rotor and an iron core in the stator, or vice versa. For simplicity, the former case will be described below.

[0036] Here, we will explain permeability. Permeability, also known as magnetic permeability, refers to the ease with which magnetic flux passes through. If we define permeability as P, magnetic permeability as μ, magnetic path length as l, and magnetic path cross-sectional area as S, then P = μS / l holds true. That is, the larger the magnetic permeability μ, the larger the magnetic path cross-sectional area S, and the shorter the magnetic path length l, the larger the permeability 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 permeability P becomes. Furthermore, the reciprocal of permeability P, which represents the difficulty of magnetic flux passing through, is called magnetoresistance. Therefore, the case where permeability P decreases in one direction from one end of the axial direction to the other has the same meaning as the case where magnetoresistance increases in one direction from one end of the axial direction to the other.

[0037] To passively achieve stability, the attractive force between the rotor's permanent magnets and the stator's iron core is utilized. For example, when the rotor is axially displaced, magnetic flux flows between the rotor's permanent magnets and the stator's iron core, separated by a radial gap, generating an attractive force that causes the rotor's axial displacement to reverse. As a result, without control, a restoring force is generated in the opposite direction to the axial displacement. The attractive force acting between the permanent magnets and the iron core is proportional to the distance and can therefore be considered a spring force. Hereinafter, this axial force will be referred to as the axial restoring force fz. Furthermore, the ratio of the axial restoring force fz to the axial displacement Δz will be called the restoring force coefficient kz. Additionally, the axial forces in each region generated by the gap will be further categorized as axial restoring forces fz. 1Z Axial restoring force f 2Z The total axial restoring force fz acting on the rotor becomes these axial restoring forces f 1Z Axial restoring force f 2Z The sum of others.

[0038] As described above, an axial restoring force fz is generated between the rotor and stator. However, if the value of the axial restoring force fz is small, the stability of the magnetic levitation will decrease, leading to problems such as the reduction in the area of ​​supporting force and torque generated between the stator and rotor due to the increase in axial displacement, causing the rotor to detach from the stator. This problem becomes more pronounced if the axial length of the rotor is short. That is, even with a small axial displacement of the rotor, if the axial length of the rotor is already short, the ratio of the relative areas of the stator and rotor is significantly reduced. This means that the ratio of torque and supporting force generated by a small axial displacement of the rotor may be significantly reduced compared to the original. In the case of a 2-axis control type, the rotor's axial length is usually designed to be smaller than the rotor's radius. Therefore, the overall device becomes flat, making it impossible to avoid a relative reduction in the axial length of the rotor.

[0039] Implementation method 1.

[0040] Figure 1 This is a bottom view showing the structure of the bearingless electric motor 1 of the electromagnetic rotating machinery as described in Embodiment 1. Figure 1 In this context, the z-direction corresponds to the vertical direction (up and down), and the xy-plane is perpendicular to the z-axis. Figure 1The bearingless motor 1 is viewed from below in the xy plane. The bearingless motor 1 has a stator 10 and a rotor 20. The stator 10 has a stator core 11 and windings (not shown). The stator core 11 has a rear yoke 12 forming the outer peripheral magnetic circuit and multiple teeth 13. Multiple teeth 13 protrude inwards from the rear yoke 12. Each tooth 13 has a tooth body 13a and multiple flange-shaped tooth front ends 13b protruding circumferentially from the front end of the tooth body 13a to both sides. The tooth front ends 13b have an upper tooth front end 13b1 and a lower tooth front end 13b2, the details of which will be described later. The stator core 11 can be a thick block of strong magnets such as iron, or a stack of steel plates, or a powder-pressed iron core.

[0041] The rotor 20 has a rotor core 21 and multiple permanent magnets 22. The rotor 20 is positioned inside the stator 10, separated by a gap 2. For simplicity, the winding diagram is omitted, but as windings, two types can be provided: a support winding for suspending the stator 10 and a motor winding for generating torque, or only a support winding can be provided. Only one type of winding can be prepared, in which current for generating support force and current for generating torque flow. Due to the presence of the permanent magnets 22, even if no bias current flows in the winding, bias magnetic flux will pass between the stator 10 and the rotor 20 through the gap 2. Furthermore, due to the presence of the permanent magnets 22, a magnetic torque for rotating the rotor 20 can be generated, enabling it to function as a bearingless motor. The rotor core 21 can be a thick block of strong magnets such as iron, a stack of steel plates, or a powder-pressed iron core.

[0042] Figure 2 This is a bottom view showing the structure of the magnetic bearing 3 in the electromagnetic rotating machinery as described in Embodiment 1. Figure 2 In the middle, the magnetic bearing 3 is observed from the bottom in the xy plane. Figure 3 This is a cross-sectional view showing the structure of the magnetic bearing 3 of the electromagnetic rotating machinery as described in Embodiment 1. Figure 3 Through the xz plane Figure 2 Cut off. In the magnetic bearing 3, the rotor 20 only has a rotor core 21, and there is no permanent magnet 22. The structure of the stator 10 is the same as... Figure 1 Same. Figure 2 The diagram of winding 14 is omitted, but... Figure 3 The middle diagram shows winding 14.

[0043] The magnetic bearing 3 has a stator 10 and a rotor 20. The stator 10 has a stator core 11 and a winding 14. The stator core 11 has a rear yoke portion 12 that forms the outer peripheral magnetic circuit and a plurality of teeth 13. The plurality of teeth 13 protrude inward from the rear yoke portion 12. Each tooth 13 has a tooth body portion 13a and a plurality of flange-shaped tooth front ends 13b that protrude from the front end of the tooth body portion 13a in the circumferential direction to both sides. The tooth front ends 13b have an upper tooth front end 13b1 and a lower tooth front end 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 via a gap 2. In this case, since the magnetic bearing 3 does not have a permanent magnet in the rotor 20, a bias current needs to flow in the winding 14. However, by having permanent magnets in the rotor 20 or the stator 10, a bias current can be eliminated. Figure 2 The structure has the advantage of not generating copper losses caused by bias current.

[0045] Next, use Figure 3 The principle of the radial support force generation of the magnetic bearing 3 is explained. Furthermore, in Figure 3 In the upper section, the front end 13b1 of the upper tooth and the front end 13b2 of the lower tooth are actually coplanar with the rotor core 21, but they are stepped to facilitate visual identification of the upper and lower sections. Here, the case where a supporting force is generated in the x-direction will be explained. A winding 14 is wound on the tooth body portion 13a on the positive x-axis (right side) and on the negative x-axis (left side). The winding 14 on the positive x-axis (right side) carries the sum of the bias current I and the changing current i, i.e., I+i. The winding 14 on the negative x-axis (left side) carries the difference between the bias current I and the changing current i, i. In this case, the magnetic flux density can be increased or decreased in the gap portion 2. Furthermore, if we consider 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 we set the constant as k, the force acting on the surface of the gap portion 2 on the positive x-axis (right side) becomes 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 called k(I-i). 2 The difference between these forces is (4×k×I×i). Therefore, the rotor 20 experiences a force of (4×k×I×i) in the positive x-axis direction. That is, after the bias current I flows, if the variable current i flowing in each tooth 13 is adjusted, a radial force proportional to the variable current i can be generated. If a supporting force is also desired in the y-axis direction, the variable current i flowing in the other windings can be adjusted similarly. As a result, it can function as a magnetic bearing that generates a radial supporting force.

[0046] Figure 4This is a perspective view showing a portion of the structure of the stator core 11 of the electromagnetic rotating machinery according to Embodiment 1. Figure 4 The stator core 11 shown will Figure 1 A portion of the stator core 11 of the bearingless electric motor 1 shown is illustrated in an enlarged view. Additionally, Figure 4 The stator core 11 shown will Figure 2 , 3 The stator core 11 of the magnetic bearing 3 is shown in an enlarged view. When the winding (not shown) is wound around the tooth body 13a of the tooth section 13 and energized, a radial electromagnetic support force is generated in the rotor 20, thereby generating torque to make the rotor 20 rotate.

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

[0048] The width W1 of the upper tooth front end 13b1 is greater than the width W2 of the lower tooth front end 13b2. That is, in Embodiment 1, the tooth front end 13b is configured such that its width decreases in one direction from the axial end where the upper tooth front end 13b1 exists to the axial end where the lower tooth front end 13b2 exists. As a result, the magnetic circuit cross-sectional area S2 of the lower tooth front end 13b2 is smaller than the magnetic circuit cross-sectional area S1 of the upper tooth front end 13b1 per unit shaft length. Figure 4 In the diagram, the amount of the two layers in the stacked structure corresponds to the unit shaft length. The shaded magnetic circuit cross-sectional area S1 corresponds to the area per unit shaft length of the portion of the upper tooth front end 13b1 opposite to the rotor 20. The shaded magnetic circuit cross-sectional area S2 corresponds to the area per unit shaft length of the portion of the lower tooth front end 13b2 opposite to the rotor 20.

[0049] That is, the transmittance P of the magnetic flux through the lower tooth section is smaller than that through the upper tooth section. In this configuration, the gap surface between the stator 10 and the rotor 20 is not tapered as in Patent Document 1, so even if the rotor 20 moves axially, it will not contact the stator 10. Furthermore, tooth front ends can be provided in addition to the upper tooth front end 13b1 and the lower tooth front end 13b2, so that the circumferential width of the tooth front end 13b, i.e., the tooth front end 13b, satisfies the condition that it decreases in one direction from one end to the other in the axial direction. For example, a middle tooth front end with a shorter circumferential width than the upper tooth front end 13b1 and a longer circumferential width than the lower tooth front end 13b2 can be provided between the upper tooth front end 13b1 and the lower tooth front end 13b2. Alternatively, a tooth front end with a shorter circumferential width compared to the front end end 13b2 of the lower tooth can be provided on the axially negative side. This will be discussed later. Figure 10 Please provide an explanation.

[0050] use Figure 5 The magnetic circuit and transmittance P in the upper stator core 11-1 are explained. Figure 5 This is an xy-sectional view showing the structure of the stator core 11-1 of the upper section of the electromagnetic rotating machinery in Embodiment 1. (See attached image.) Figure 5 As shown, a surrounding magnetic circuit J is formed around the stator 10 and rotor 20 through the gap 2. The surrounding magnetic circuit J can be mainly divided into two directions: radial and circumferential. The surrounding magnetic circuit J has a tooth tip transmittance P1, a gap transmittance P2, a rotor transmittance P3, a tooth body transmittance P4, and a rear yoke transmittance P5. If the width W1 of the upper tooth tip 13b1 is increased, the cross-sectional area of ​​the magnetic circuit attempting to pass through the upper tooth tip 13b1 increases, and the transmittance P of the tooth tip 13b increases.

[0051] use Figure 6 The magnetic circuit and transmittance P in the lower stator core 11-2 are explained. Figure 6 This is an xy cross-sectional view showing the structure of the lower stator core 11-2 of the electromagnetic rotating machinery according to Embodiment 1. In the lower stator core 11-2, the surrounding magnetic circuit J also has a tooth tip transmittance P1, a gap transmittance P2, a rotor transmittance P3, a tooth body transmittance P4, and a rear yoke transmittance P5. As mentioned above, the width W2 of the lower tooth tip 13b2 is smaller than the width W1 of the upper tooth tip 13b1. As a result, the cross-sectional area of ​​the magnetic circuit attempting to pass through the lower tooth tip 13b2 becomes smaller, and the transmittance P of the tooth tip 13b decreases.

[0052] Figure 7This is a perspective view showing a portion of the structure of the stator 10 and rotor 20 of the electromagnetic rotating machine according to Embodiment 1, showing the state in which the rotor 20 generates a displacement of Δz in the axial direction. Figure 8 This is a perspective view showing a portion of the structure of the stator 10 and rotor 20 of the electromagnetic rotating machine according to Embodiment 1, illustrating a state where the rotor 20 does not produce axial displacement. Figure 7 and Figure 8 The principle of increased axial restoring force when the front end 13b of the tooth is configured as a two-section structure with an upper and lower section is explained. A model of the stator 10 and rotor 20 cut through the xz plane is shown. Furthermore, for simplicity, lines representing the stacked structure are not shown.

[0053] When this electromagnetic rotating machinery is used for applications such as fans, blowers, or pumps, the reaction force from the gas or liquid expelled from the blades mounted on the rotor 20 acts on the rotor 20. Additionally, regardless of the presence or absence of blades, the gravitational force mg generated by the mass of the rotor 20 itself acts on the rotor 20. Figure 7 , Figure 8 The diagram illustrates a configuration where the rotation axis is vertically aligned, with the weight mg of the rotor 20 acting axially. The vertically upward direction is defined as the positive z-axis. In this case, the rotor 20 attempts to move in the vertically downward direction, i.e., the negative z-axis, due to forces such as gravity mg. However, as previously described, when the rotor 20 experiences axial displacement, an axial restoring force fz is generated in the opposite direction to the displacement. Therefore, the rotor 20 is suspended at a position where these forces are balanced. A portion of the magnetic flux is concentrated at the lower end 13c1 of the tooth 13, thus generating the axial restoring force fz. 1Z The axial restoring force f 1Z It can also be produced in a general shape without changing the width dimension of the front end 13b of the tooth.

[0054] On the other hand, in Embodiment 1, the width W1 of the upper tooth front end 13b1 is made greater than the width W2 of the lower tooth front end 13b2. Therefore, below the upper tooth front end 13b1, in other words, in the middle portion 13c2 of the tooth portion 13 in the vertical direction, the flange portion of the upper tooth front end 13b1 protrudes further circumferentially compared to the flange portion of the lower tooth front end 13b2, and the magnetic flux is also concentrated here. This is because there is a difference in transmittance P between the upper and lower tooth portions. In other words, the transmittance P decreases in one direction from one end to the other in the axial direction. Therefore, a new axial restoring force f is also generated in the middle portion 13c2 of the tooth portion 13 in the vertical direction. 2Z As described above, by setting the front end 13b of the tooth as a two-section structure of upper and lower sections, the axial restoring force fz increases in one direction.

[0055] In addition, such as Figure 8As shown, when the rotor 20 does not undergo axial displacement, no axial restoring force f is generated due to the rotor 20 and stator 10 not being axially relative. 1Z However, this will generate an axial restoring force f, which is produced by constructing the tooth tip 13b as a two-section structure with an upper and a lower section. 2Z The above situation is described by a formula. If the resultant force of the forces acting axially on rotor 20 is denoted as F... Z Then the resultant force F Z This includes gravity mg, the disturbance d caused by the aforementioned reaction force, and the axial restoring force f. 1Z With axial restoring force f 2Z The sum of these equations gives the equation for motion along the axial direction.

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

[0057] Axial restoring force f 1Z It is proportional to the axial displacement Δz. If the axial restoring force coefficient is set as kz, then it becomes 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 displacement. Axial restoring force f 2Z It relates to the magnetic flux between the stator 10 and the rotor 20 in the intermediate section 13c2, but it is almost independent of the axial displacement Δz of the rotor 20, and therefore can be considered a constant. If the width W1 of the front end 13b1 of the upper tooth is made greater than the width W2 of the front end 13b2 of the lower tooth, then it becomes f 2Z >0. Therefore, the equation of motion for the axial direction becomes the following equation.

[0058] F Z =-mg+d-kz·Δz+f 2Z

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

[0060] Δz=(-mg+d+f 2Z ) / kz

[0061] In the axial restoring force f 2Z With the width of the tooth tip 13b constant and Δz = (-mg+d) / kz, the position balanced by gravity mg and the amount of disturbance d is axially offset. However, as shown in Embodiment 1, when f 2Z When the value is greater than 0, the equilibrium position is close to Δz = 0. Under the axial restoring force f... 2Z The sum of the gravity mg of rotor 20 and the disturbance d balances to become f.2Z In the case of mg - d, the rotor 20 can continue to be suspended even at the position where Δz = 0. For simplicity, we will assume the disturbance d = 0 below.

[0062] Figure 9 This is a graph showing the relationship between axial displacement and axial restoring force in the electromagnetic rotating machine of Embodiment 1 and the comparative example. Figure 9 In the diagram, the horizontal axis represents the axial displacement Δz, showing the situation where the rotor 20 moves further to the right of the horizontal axis, resulting in a more negative axial displacement compared to the origin. The vertical axis represents the axial restoring force f. z , becoming the axial restoring force f 1Z With axial restoring force f 2Z The value of the sum. In Figure 9 The values ​​shown are those obtained by normalizing the vertical and horizontal axes. The thick solid lines, as shown in Embodiment 1, correspond to the case where the tooth tip 13b is configured as a two-segment structure with an upper and lower segment. The dashed lines correspond to the comparative example and to the case where the width of the tooth tip 13b is constant. Figure 9 The results show the analytical results obtained by using the finite element method to analyze the relationship between axial displacement and axial restoring force.

[0063] In both the one-segment structure (comparative example) and the two-segment structure (implementation 1), it is evident that the greater the axial displacement, the greater the axial restoring force. This refers to the aforementioned axial restoring force f. 1Z The influence of this. Furthermore, the two-segment structure (Implementation Method 1) deviates further from the relationship of the one-segment structure (Comparative Example) by increasing by a certain value. This increase is related to the axial restoring force f. 2Z The effect corresponds to this. The equilibrium position relative to gravity can be determined simply by drawing a horizontal line and calculating the point where gravity and the axial restoring force overlap. Q1 is the equilibrium position in the comparative example, and Q2 is the equilibrium position in implementation method 1. Based on this analysis, it can be seen that the equilibrium position in implementation method 1 is closer to the origin than that in the comparative example.

[0064] Figure 10 This is a perspective view showing a portion of the structure of a modified example of the stator core 11 of the electromagnetic rotating machinery according to Embodiment 1. As mentioned above, the number of segments that change the width dimension of the tooth tip 13b can be set to more than or equal to three segments instead of two. Figure 10 In the middle section, the tooth front end 13b has an upper tooth front end 13b1, a middle tooth front end 13b3, and a lower tooth front end 13b2, such that the width W1 of the upper tooth front end 13b1 > the width W3 of the middle tooth front end 13b3 > the width W2 of the lower tooth front end 13b2. Alternatively, the width dimension of the tooth front end of all the laminated steel plates can be changed so that the width dimension does not change to a stepped shape, but rather to a straight line.

[0065] Furthermore, while the description above pertains to an inner rotor type where the stator 10 is positioned on the outer side and the rotor 20 on the inner side, embodiment 1 can also be applied to an outer rotor type where the stator 10 is positioned on the inner side and the rotor 20 on the outer side. That is, in this case, by varying the width dimension of the tooth tip 13b of the stator 10 in the z-direction into multiple segments or a straight line, the same effect as described above is achieved.

[0066] Furthermore, while the above description focused on the case where the rotor 20 has a permanent magnet and the stator 10 has an iron core, 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 varying the width of the tooth tip portion of the inner rotor type or outer rotor type rotor in one direction (z-direction) into multiple segments or a straight line, the same effect as described above can be obtained.

[0067] Furthermore, as described above, the weight mg of rotor 20 is assumed to generate an axial restoring force f in the opposite direction of the weight mg of rotor 20. 2Z The case where the tooth tip 13b is constructed in a multi-segment manner has been described, but it can also handle forces other than gravity mg. For example, in a pump that circulates liquid by attaching blades to the rotor 20, an axial reaction will also occur. The direction of this reaction force is predetermined to be one direction, so it is possible to shorten the width dimension of the tooth tip 13b in one direction so that the axial restoring force is increased in the opposite direction of the reaction.

[0068] In addition, Figure 1 The diagram shows a surface magnet type where a permanent magnet 22 is disposed on the surface of the rotor 20, but embodiment 1 can also be applied to an embedded magnet type where the permanent magnet 22 is disposed in the core of the rotor 20. Additionally, embodiment 1 can also be applied to a motor that utilizes reluctance torque without a permanent magnet 22 disposed on the rotor 20 side.

[0069] Furthermore, it is preferable to design the rotor 20 such that its shaft length (axial length) is shorter than its radius. By configuring it in this way, the restoring force coefficient kz and the axial restoring force f... 1Z Increase. Furthermore, in the axial restoring force f 2Z Based on the effect, the position of balance is closer to the origin.

[0070] Figure 11 This is a developed diagram showing a modified example of the electromagnetic rotating machinery according to Embodiment 1. Figure 11In this configuration, a sensor 16 is disposed in the region 15 between the front ends 13b2 of adjacent lower teeth. The slot opening width of the region 15 between the front ends 13b2 of adjacent lower teeth is expanded, thus ensuring sufficient space for configuring various components. A base for the sensor 16, a holding mechanism, wiring for the sensor 16, winding connections, or refrigerant piping for cooling can be disposed in region 15. Alternatively, a sensor 16 for detecting ambient temperature, magnetic flux density, or distance from the rotor 20 can also be disposed. The sensor 16 can be a Hall element, a thermocouple, or an eddy current displacement sensor. In this case, on the lower section side where the slot opening width is expanded, magnetic flux from the permanent magnet 22 of the rotor 20 to the Hall element sensor, or from the eddy current sensor to the rotor 20, is easily transmitted. The reason is that if the flange of the tooth 13 protrudes significantly, the sensitivity of the sensor 16 decreases due to the magnetic flux flowing in the flange. However, this phenomenon can be suppressed by expanding the width of the slot opening on the lower side. Furthermore, as... Figure 10 As shown, when the tooth tip has three or more segments, it becomes difficult from a spatial point of view to place the sensor 16 on the side of the upper tooth tip 13b1. However, the same effect can be achieved by placing it on the side of the middle tooth tip 13b3 and the lower tooth tip 13b2. In this case, the best effect can be achieved by placing the sensor 16 on the side of the lower tooth tip 13b2, where the slot opening width is the largest.

[0071] As described above, according to Embodiment 1, the transmittance P, which represents the ease with which magnetic flux passes through at least one of the gap portion and the core in the surrounding magnetic circuit J that causes the stator 10 and rotor 20 to rotate radially and circumferentially, decreases in one direction from one end of the axial direction to the other. Specifically, the width dimension of the tooth tip 13b of the tooth portion 13 is varied in multiple segments or a straight line in one direction of the z-direction. Therefore, it is not necessary to make the gap surface between the stator 10 and rotor 20 conical or the like, which does not worsen the assembly disassembly and allows the axial restoring force of the rotor 20 to increase in one direction. In addition, the gap between the rotor 20 and stator 10 can be reduced, so magnetic flux passes easily between the stator 10 and rotor 20, and the current required to generate the same torque and support force can be reduced. As a result, effects such as reduced heat generation and increased efficiency are obtained.

[0072] Furthermore, according to Embodiment 1, even if the rotor 20 does not undergo axial displacement, it can still generate an axial restoring force f. 2Z .like Figure 8 As shown, if the rotor 20 does not undergo axial displacement, the weight mg and the axial restoring force f of the rotor 20 are... 2ZWhen balanced, all axial regions of the stator 10 and rotor 20 are relative to each other. Therefore, the supporting force and torque generated when the current between the stator 10 and rotor 20 is set to the same value increase. As a result, copper losses are reduced when the same supporting force and torque are generated.

[0073] Furthermore, according to Embodiment 1, only the width of the tooth tip 13b is changed; the inner diameter of the stator 10 and the outer diameter of the rotor 20 are not altered. Therefore, the movable area 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, axial, or tilting direction, contact occurs between the rotor 20 and the stator 10 at their protruding portions or where the gap narrows, resulting in a reduction in the movable area of ​​the rotor 20. According to Embodiment 1, this disadvantage is avoided, and the axial force generated in the rotor 20 can be increased.

[0074] Implementation method 2.

[0075] Figure 12 This is a perspective view showing a portion of the structure of the stator core 11 of the electromagnetic rotating machinery according to Embodiment 2. Figure 12 In order to improve visual recognition, the direction of the z-axis is made relative to... Figures 1-4 The view is rotated 180 degrees to show a perspective view from below. In Embodiment 2, the tooth body portion 13a is also configured as a segment structure with two or more segments, such that the circumferential width W4 of the upper tooth body portion 13a1, which is the first tooth body portion, is greater than the circumferential width W5 of the lower tooth body portion 13a2, which is the second tooth body portion. Furthermore, the rear yoke portion 12 is also configured as a segment structure with two or more segments, such that the radial width W6 of the upper rear yoke portion 12-1, which is the first rear yoke portion, is greater than the radial width W7 of the lower rear yoke portion 12-2, which is the second rear yoke portion.

[0076] Therefore, compared to the upper section, the cross-sectional area of ​​the magnetic circuit in the lower section is smaller, and the transmittance P is smaller. Consequently, magnetic flux passes more easily between the upper section of stator 10 and rotor 20 compared to the lower section of stator 10 and rotor 20, resulting in lower axial magnetic flux and axial restoring force f. 2Z Increase. Therefore, if the construction of Embodiment 2 is adopted to match the change in the width dimension of the tooth tip 13b, the axial restoring force f 2Z Further increases. In addition, by shortening the width of the tooth body 13a and the rear yoke 12, the overall weight reduction of the device is achieved.

[0077] In addition, Figure 12 The diagram shows a case where the width dimensions of both the tooth body portion 13a and the rear yoke portion 12 have been changed, but it is also possible to change the width dimension of only one of them. Furthermore, in... Figure 12Not shown in the figure, but when the winding is wound around the tooth 13, the width dimension of the lower section becomes shorter, thereby shortening the circumference of the winding. Therefore, resistance and copper loss can be reduced. Furthermore, since the angle when the winding is wound around the lower section is greater than 90 degrees, winding expansion can be suppressed. As a result, the area at the winding end can be reduced, and based on the aforementioned reduction in copper loss, the overall device can be miniaturized and lightweighted. Additionally, by varying the width of the tooth tip 13b, the effects described in Embodiment 1 can also be obtained. However, it is also possible to have no variation in the width of the tooth tip 13b.

[0078] Furthermore, the shorter width W5 of the lower tooth body portion 13a2 also suppresses the winding expansion, thereby ensuring the narrow space between them. As a result, the sensor 16, other holding mechanisms, etc., can be configured at this position in the same manner as in Embodiment 1. In addition, when the sensor 16 is radially long and must be configured to span both the tooth front ends 13b and the tooth body portions 13a, the area of ​​the sensor 16 can be secured throughout its entire length.

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

[0080] Implementation method 3.

[0081] Figure 13 This is a perspective view showing a portion of the structure of the stator core 11 of the electromagnetic rotating machinery according to Embodiment 3. Figure 14 This is a perspective view showing a portion of the structure of a modified example of the stator core 11 of the electromagnetic rotating machinery according to Embodiment 3. Figure 13 , Figure 14 In, also with Figure 12 Similarly, a perspective view of the stator core 11 viewed from below is shown. Furthermore, for simplicity, lines indicating the laminated structure are not shown.

[0082] exist Figure 13 In the middle section, a slot 17 is provided on the clearance surface of the lower tooth front end 13b2 opposite to the rotor 20. The slot 17 does not have a winding wound around it, but rather forms a narrow slot; therefore, this slot 17 is also called a dummy slot. Figure 13In the middle section, the groove 17 is only present in the lower section, thus forming an upper exposed surface 17a on the upper section side of the groove 17, where a portion of the upper tooth front end 13b1 is exposed. According to this structure, a magnetic flux is generated that passes obliquely between the upper exposed surface 17a of the upper tooth front end 13b1 and the rotor 20, resulting in an axial restoring force f. 2Z This can be further increased. It can also be considered that through the slot 17, magnetic flux is not easy to pass through a part of the front end 13b2 of the lower tooth, and the transmittance P is reduced.

[0083] exist Figure 14 In this design, a groove 17, serving as a second groove, is provided on the clearance surface of the lower tooth's front end 13b2, and a groove 18, serving as a first groove, is provided on the clearance surface of the upper tooth's front end 13b1. Furthermore, the size of groove 17 is larger than the size of groove 18. The size of groove 17 is either a width dimension L1 or a depth dimension L2; both can be varied, or only one dimension can be changed. By configuring it in the above manner, it can be combined with… Figure 13 Similarly, it is possible to produce the upper exposed surface 17a.

[0084] As described above, according to Embodiment 3, in order to reduce the transmittance P in one direction from one end of the axial direction to the other, a groove 17 is provided on the gap surface of the lower tooth tip 13b2. Therefore, not only is the axial restoring force increased, but the waveform or peak value of the cogging torque generated between the stator 10 and the rotor 20 when no power is applied can also be adjusted. Generally, it is preferable to have a small cogging torque, but the effect of reducing the cogging torque can also be obtained simultaneously. In addition, by adding a difference to the width of the tooth tip 13b or the width of the tooth body 13a, the effects described in Embodiments 1 and 2 can also be obtained. However, by designing only the groove 17, the effect of increasing the axial restoring force in one direction can also be achieved.

[0085] Implementation method 4.

[0086] Figure 15This is a perspective view showing a portion of the structure of the stator core 11 of the electromagnetic rotating machine according to Embodiment 4. In Embodiment 4, the materials of the cores are changed in the upper stator core 11-1 and the lower stator core 11-2. The upper stator core 11-1 uses a high flux density material, while the lower stator core 11-2 uses a low flux density material. The 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. A high flux density material refers to, for example, a material with a large flux density value relative to the same magnetic field strength. For example, a directional electromagnetic steel plate can be used in the upper stator core 11-1, and a non-directional electromagnetic steel plate can be used in the lower stator core 11-2. Furthermore, the characteristics of the magnetic flux density corresponding to the overall magnetic field strength of the region can be altered by varying the duty cycle of the laminated steel plates. This means, for example, setting a difference such as setting the duty cycle of the upper stator core 11-1 to 96% and the duty cycle of the lower stator core 11-2 to 92%, thus changing the overall magnetic properties of the region even if the individual laminated steel plates are made of the same material. This change can be described as altering the permeability. As mentioned above, the transmittance P is a function of the permeability, and therefore, the result allows for axial variation of the transmittance P.

[0087] As described above, according to Embodiment 4, in order to reduce the transmittance P in one direction from one end of the axial direction to the other, 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 2 increases. As a result, the axial restoring force f generated between the rotor 20 and the stator 10... 2Z Further increases are possible. Furthermore, the shape design described in embodiments 1-3 is preferred, but the effect can also be achieved simply by changing the material.

[0088] Implementation method 5.

[0089] Figure 16 This is a perspective view showing a portion of the structure of the stator and rotor of the electromagnetic rotating machine according to Embodiment 5. Figure 17 This is an xz cross-sectional view showing the structure of the electromagnetic rotating machinery in Embodiment 5. Figure 16For visual clarity, an oblique view viewed from the lower 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 varied in a segmented or linear manner, decreasing in length from one axial end to the other. If the viewing method is changed, it can be said that the gap length is varied in a segmented or linear manner, increasing in length from one axial end to the other. 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 different, with the inner diameter D3 of the upper stator core 11-1 being 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 13b. If the upper section of tooth 13 is designated as the first tooth section and the lower section of tooth 13 is designated as the second tooth section, then it can be considered that the first tooth section having the front end of the first tooth and the second tooth section having the front end of the second tooth with an inner diameter larger than the front end of the first tooth are arranged axially. Preferably, the gap in the second tooth section is wider than the gap in the first tooth section, and the second tooth section is arranged to be vertically below. Furthermore, the case of expressing the gap length as long or short has the same meaning as the case of expressing the gap as wide or narrow.

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

[0091] In Embodiment 5, the inner diameter of the stator core 11 is set to D3 < D2. Furthermore, if the outer diameter of the rotor 20 is set to D1, then D1 < D3. As a result, even if the rotor 20 is axially movable, the rotor 20 will not contact the stator 10. Consequently, assembly disassembly is not compromised. In Patent Document 1, both the inner diameter of the stator 10 and the outer diameter of the rotor 20 are changed. Therefore, multiple shapes of both the stator 10 and the rotor 20 are required, increasing manufacturing costs. However, in Embodiment 5, the shape of only one of the stator 10 and the rotor 20 is changed, thus suppressing the increase in manufacturing costs. In particular, manufacturing magnets with different diameters or tilted shapes presents difficulties. However, in Embodiment 5, only the inner diameter of the stator core 11 needs to be changed, and there is no increase in magnet manufacturing costs. Furthermore, the difference between the inner diameters D3 and D2 of the stator 10 can be, for example, about 0.1 mm to 1 mm, or there can be almost no difference in shape. For example, after the upper stator core 11-1 with a small inner diameter is manufactured in one go, the inner diameter of this part can be expanded by additional processing to manufacture the lower stator core 11-2.

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

[0093] Furthermore, in the case of an external rotor type where 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 changing the axial position, it is equivalent to changing the outer diameter of the stator 10.

[0094] As described above, according to Embodiment 5, in order to reduce the transmittance P in one direction from one end of the axial direction to the other, the inner diameter of the stator core or the gap length between the stator 10 and the rotor 20 is varied in a multi-segment or linear manner, shortening in one direction from one end of the axial direction to the other. Therefore, assembly decomposition is not worsened, and the axial restoring force of the rotor 20 can be increased in one direction. Furthermore, the gap between the rotor 20 and the stator 10 can be reduced, thus facilitating the passage of magnetic flux between the stator 10 and the rotor 20, reducing the current required to generate the same torque and support force. As a result, effects such as reduced heat generation and increased efficiency are achieved.

[0095] Implementation method 6.

[0096] Figure 18 This is a diagram illustrating the principle of adjusting the axial restoring force of the electromagnetic rotating machinery in Embodiment 6. Figure 19 This diagram illustrates the principle of adjusting the axial restoring force of the electromagnetic rotating machinery in Embodiment 6. Figure 18 and Figure 19 In the middle, rotor 20 was displaced in the -z direction. Figure 18 and Figure 19 In the winding 14, the direction of the current flowing in the winding is different. Figure 20 This is a diagram illustrating the principle of adjusting the axial restoring force of the electromagnetic rotating machinery in Embodiment 6. Figure 21 This diagram illustrates the principle of adjusting the axial restoring force of the electromagnetic rotating machinery in Embodiment 6. Figure 20 and Figure 21 In the middle, rotor 20 did not produce any displacement. Figure 20 and Figure 21 In the winding 14, the direction of the current flowing in the winding is different.

[0097] Normally, without axial displacement of the rotor 20, no axial restoring force is generated in the rotor 20. However, as mentioned above, the transmittance P in the magnetic circuit that causes the stator 10 and rotor 20 to rotate in the radial and circumferential directions, i.e., the width of the tooth tip 13b of the tooth 13, the circumferential width of the tooth body 13a, the inner diameter of the tooth tip 13b, or the material of the stator core 11, varies in one direction (z) as multiple segments or a straight line. Therefore, even without 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 the bias current or magnet. As mentioned above, the axial restoring force f is generated proportional to the axial displacement of the rotor 20. 1Z And the axial restoring force f that is constant and independent of axial displacement 2Z However, these two can be increased or decreased by the d-axis current.

[0098] exist Figures 18-21 The image shows a rotor 20 with a permanent magnet 22. Figure 18 The diagram illustrates a case where a positive d-axis current flows through winding 14, thereby enhancing the magnetic flux Φ1 generated by permanent magnet 22. In this case, the magnetic flux Φ2 generated through winding 14 (shown by dashed lines) further enhances the magnetic flux Φ1 generated through permanent magnet 22 (shown by solid lines). Consequently, the axial restoring force f generated is proportional to the axial displacement. 1Z and axial restoring force f 2Z Increase. On the other hand, in Figure 19 In the diagram, the magnetic flux Φ1 generated by the permanent magnet 22 (shown by the solid line) and the magnetic flux Φ2 generated by the winding 14 (shown by the dashed line) are oriented in opposite directions and weaken each other. As a result, the axial restoring force f... 1Z and axial restoring force f 2Z reduce.

[0099] Figure 20 and Figure 21 The diagram shows the case where the rotor 20 has no axial displacement (z = 0). In this case, the axial restoring force f is proportional to the axial displacement. 1Z It becomes 0. However, an axial restoring force f is generated. 2Z Its value can be increased or decreased through the d-axis current. Figure 20 In the winding 14, a positive d-axis current flows to enhance the magnetic flux Φ1 and the axial restoring force f. 2Z Increase. In Figure 21 In the middle, a negative d-axis current flows in winding 14 to weaken the magnetic flux Φ1 and the axial restoring force f. 2Z reduce.

[0100] This can be explained using a formula. Let the d-axis current be i. d Additionally, the axial restoring force f is generated by the d-axis current. 1Z The change is (1+k) Zi1 ·i d ) times. Here, k Zi1 This indicates that the axial restoring force f is caused by the current through the d-axis. 1Z The coefficient of the changing ratio. Additionally, let f be the axial restoring force caused by the d-axis current. 2Z The change is (1+k) Zi2 ·i d ) times. Here, k Zi2 This indicates that the axial restoring force f is caused by the current through the d-axis. 2Z The coefficient of the changing proportion. The equation of motion for the axial direction 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 absence of axial displacement (z=0), the equation of motion for the axial direction becomes the following equation.

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

[0104] Therefore, in any cases where z < 0 and z = 0, if there is a control device to increase or decrease the d-axis current id, then the resultant force F acting on the rotor 20 in the axial direction can be controlled. Z Adjustments can be made. Furthermore, even when z > 0, the resultant axial force F acting on rotor 20 can also be adjusted. Z Adjustments will be made.

[0105] To ensure stable magnetic levitation, reducing the vibration of the rotor 20 is crucial. Therefore, any control device capable of detecting the axial vibration of the rotor 20 and adjusting the d-axis current flowing in the winding 14 accordingly can suffice. That is, according to Embodiment 6, even without axial displacement, the axial restoring force can be adjusted to reduce axial vibration.

[0106] The structures shown in the above embodiments represent a part of the content of the present invention, and can also be combined with other known technologies. Without departing from the scope of the present invention, appropriate combinations can be made, or parts of the structure can be omitted or modified.

[0107] Explanation of the label

[0108] 1. Bearingless motor; 2. Gap section; 3. Magnetic bearing; 10. Stator; 11. Stator cores (11-1, 11-2); 12. Rear yoke; 12-1 Upper rear yoke section; 12-2 Lower rear yoke section; 13. Tooth section; 13a. Tooth body; 13a1 Upper tooth body; 13a2 Lower tooth body; 13b. Tooth front end; 13b1 Upper tooth front end; 13b2 Lower tooth front end; 13b3 Middle tooth front end; 13c1 Lower end; 13c2 Middle section; 14. Winding; 15. Region; 16. Sensor; 17. Slots; 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: Rotor; and The stator is configured with a gap relative to the rotor. A supporting force is generated by electromagnetic or magnetic force to levitate the rotor without contact. The electromagnetic rotating machinery is characterized by the following: At least one of the rotor and the stator has a plurality of teeth composed of multiple iron core segments for winding the winding. The permeability is a measure of the ease with which magnetic flux passes through at least one of the gap and the core in the magnetic circuit that causes the stator and the rotor to rotate in the radial and circumferential directions. This permeability is a measure of the ease with which magnetic flux passes through at least one of the following: the circumferential width of the front end of the tooth, the circumferential width of the tooth body, the radial width of the rear yoke disposed on the outer circumference of the tooth body, the circumferential width or radial length of the slot of the tooth tip, and the permeability of the tooth. This permeability decreases in one direction from one end of the axial direction toward the other end.

2. The electromagnetic rotating machinery according to claim 1, characterized in that, The circumferential width of the front end of the tooth, i.e. the front end of the tooth, decreases in one direction from one end to the other in the axial direction.

3. The electromagnetic rotating machinery according to claim 2, characterized in that, Each tooth portion is axially configured with a first tooth portion having a first tooth front end portion and a second tooth portion having a second tooth front end portion having a circumferential width smaller than the first tooth front end portion.

4. The electromagnetic rotating machinery according to claim 3, characterized in that, The second tooth is configured to be vertically below the first tooth.

5. The electromagnetic rotating machinery according to claim 1, characterized in that, Each of the teeth has a first tooth and a second tooth arranged in the axial direction. The circumferential width of the main body of the second tooth in the second tooth portion is smaller than the circumferential width of the main body of the first tooth in the first tooth portion, or The radial width of the second rear yoke portion disposed on the outer periphery of the second tooth body portion is smaller than the radial width of the first rear yoke portion disposed on the outer periphery of the first tooth body portion.

6. The electromagnetic rotating machinery according to claim 1, characterized in that, Each of the teeth comprises a first tooth portion having a first tooth front end portion and a second tooth portion having a second tooth front end portion, arranged axially. The front end of the second tooth has a groove on the surface opposite to the stator or the rotor. The front end of the first tooth does not have a groove on the surface opposite to the stator or the rotor.

7. The electromagnetic rotating machinery according to claim 1, characterized in that, Each of the teeth comprises a first tooth portion having a first tooth front end portion and a second tooth portion having a second tooth front end portion, arranged axially. The front end of the first tooth has a first groove on the surface opposite to the stator or the rotor. The front end of the second tooth has a second groove on the surface opposite to the stator or the rotor. The circumferential width or radial length of the second groove is longer than the circumferential width or radial length of the first groove.

8. The electromagnetic rotating machinery according to claim 1, characterized in that, Each of the teeth has a first tooth and a second tooth arranged in the axial direction. Compared to the material of the iron core containing the second tooth, the material of the iron core containing the first tooth produces a larger magnetic flux density in the same magnetic field strength.

9. The electromagnetic rotating machinery according to any one of claims 1 to 8, characterized in that, The inner diameter of the front end of the tooth, i.e. the tooth tip, or the length of the gap, i.e. the gap length, decreases in one direction from one end to the other in the axial direction.

10. The electromagnetic rotating machinery according to claim 9, characterized in that, Each tooth portion is axially configured with a first tooth portion having a first tooth front end portion and a second tooth portion having a second tooth front end portion having an inner diameter larger than the first tooth front end portion.

11. The electromagnetic rotating machinery according to claim 3, characterized in that, A sensor is positioned between the adjacent front ends of the second tooth.

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

13. The electromagnetic rotating machinery according to any one of claims 1 to 8, 11, and 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 that attracts the rotor relative to the stator in the axial direction.

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