Iron core, stator, and rotating electric machine

Abstract

A core used in an axial gap type rotating electric machine, the core having: a ring-shaped back yoke; and a plurality of teeth projecting in an axial direction perpendicularly to a first plane of the back yoke, the plurality of teeth being disposed at intervals in a circumferential direction of the first plane, the back yoke and the teeth being composed of an integrally formed powder compact, a first curved surface portion connecting between a circumferential surface of the tooth and the first plane of the back yoke being provided at a corner of the tooth and the back yoke, a radius of curvature of the first curved surface portion being greater than or equal to 0.2 mm and less than or equal to 1.5 mm.

Description

TECHNICAL FIELD

[0001] The present application relates to an iron core, a stator, and a rotary electric machine.

[0002] This application claims priority based on Japanese Application No. 2018-202373 filed on October 26, 2018, and incorporates by reference the entire disclosure of the above-mentioned Japanese application. BACKGROUND

[0003] Patent Documents 1 and 2 disclose an axial gap type motor (rotary electric machine) in which a rotor and a stator are arranged opposite to each other in the axial direction. The stator used in this kind of rotary electric machine has a circular ring-shaped back yoke, an iron core having a plurality of teeth protruding in the axial direction from the back yoke, and a coil arranged in each tooth. The plurality of teeth are arranged at intervals in the circumferential direction on one face (upper surface) of the back yoke.

[0004] In Patent Document 1, it is described that the iron core is configured by a powder compact integrally molded with the back yoke and the teeth.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2009-142095

[0006] Patent Document 2: Japanese Patent Application Publication No. 2017-229191 SUMMARY

[0007] The iron core of the present application is used in an axial gap type rotary electric machine,

[0008] The iron core has:

[0009] a circular ring-shaped back yoke; and

[0010] a plurality of teeth protruding in the axial direction perpendicular to a first plane of the back yoke,

[0011] the plurality of teeth are arranged at intervals in the circumferential direction of the first plane,

[0012] the back yoke and the teeth are configured by a powder compact integrally molded,

[0013] a first curved surface portion connecting between a peripheral surface of the tooth and the first plane of the back yoke is provided at a corner portion of the tooth and the back yoke,

[0014] a radius of curvature of the first curved surface portion is greater than or equal to 0.2 mm and less than or equal to 1.5 mm.

[0015] The stator of the present application is a stator of an axial gap type rotary electric machine, having:

[0016] the iron core of the present application; and

[0017] a coil arranged in each tooth of the iron core.

[0018] The rotating electric machine of the present application has a rotor and a stator, and is an axial gap type rotating electric machine in which the rotor and the stator are arranged in opposition in an axial direction,

[0019] In this rotating electric machine,

[0020] The stator is the stator of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a schematic plan view of the core involved in the embodiment.

[0022] Figure 2 is a schematic cross-sectional view along the line II-II of Figure 1

[0023] Figure 3 is a partially enlarged schematic cross-sectional view of Figure 2

[0024] Figure 4 is a schematic cross-sectional view showing one example of a mold for molding the core involved in the embodiment.

[0025] Figure 5 is a schematic plan view of a punch.

[0026] Figure 6 is a schematic cross-sectional view along the line VI-VI of Figure 5

[0027] Figure 7 is a partially enlarged schematic cross-sectional view of Figure 6

[0028] Figure 8 is a schematic plan view of a lower punch.

[0029] Figure 9 is a schematic cross-sectional view along the line IX-IX of Figure 8

[0030] Figure 10 is a partially enlarged schematic cross-sectional view showing a state in which the core is molded by the mold.

[0031] Figure 11 is a schematic plan view of the stator involved in the embodiment.

[0032] Figure 12 is a schematic cross-sectional view of the rotating electric machine involved in the embodiment.

[0033] Figure 13A is a schematic plan view of one example of the core involved in the modification.

[0034] Figure 13B ​​​​​is a cross-sectional view of a rotary electric machine using the core shown in Figure 13A is a cross-sectional view of a rotary electric machine using the core shown in

[0035] Figure 14A is a cross-sectional view of a rotary electric machine using the core shown in

[0036] Figure 14B is a cross-sectional view of a rotary electric machine using the core shown in Figure 14A is a cross-sectional view of a rotary electric machine using the core shown in DETAILED DESCRIPTION

[0037] [Problems to be Solved by the Invention]

[0038] It is desirable to improve the efficiency of a rotary electric machine of an axial gap type. From the viewpoint of improving the efficiency of a rotary electric machine, it is desirable to improve the magnetic characteristics of a core used in the rotary electric machine.

[0039] An object of the present application is to provide a core capable of improving magnetic characteristics. Another object of the present application is to provide a stator having the above-mentioned core. Further, an object of the present application is to provide a rotary electric machine having the above-mentioned stator.

[0040] [Effects of the Invention]

[0041] The core of the present application is capable of improving magnetic characteristics. Further, the stator of the present application is excellent in the magnetic characteristics of the core. Moreover, the rotary electric machine of the present application is excellent in efficiency.

[0042] [Explanation of Embodiments of the Invention]

[0043] The present inventors earnestly studied the magnetic characteristics of a core used in a rotary electric machine of an axial gap type, and as a result, obtained the following insight.

[0044] In a rotary electric machine of an axial gap type, if a current flows in a coil, magnetic flux flows through a core to form a magnetic circuit. If the magnetic flux flowing in the core decreases, the torque of the rotary electric machine decreases. In the core of the rotary electric machine, the magnetic flux flows in the teeth in the axial direction, and the magnetic flux flows in the back yoke in the circumferential direction. Therefore, the direction of the magnetic flux changes between the teeth and the back yoke.

[0045] In an iron core composed of a conventional powder compact, as shown in Patent Document 2, when molding is performed using a mold, two lower punches are generally used, and the end surface of the tooth and the first plane of the tooth-protruding back yoke are molded by the respective different lower punches. In this case, from the viewpoint of punch strength and the like, the molding is performed in such a manner that the peripheral surface of the tooth is orthogonal to the first plane of the tooth-protruding back yoke. In the iron core as described above, since the peripheral surface of the tooth is orthogonal to the first plane of the back yoke, when magnetic flux flows through the corner portion between the tooth and the back yoke, a part of the magnetic flux sometimes takes a short cut between the peripheral surface of the tooth and the first plane of the back yoke on the outside of the iron core. That is, magnetic flux leakage is easily generated at the corner portion of the tooth and the back yoke. If magnetic flux leakage is generated in the iron core of a rotating electric machine, torque reduction is caused, and the loss of the iron core increases to cause efficiency reduction.

[0046] The present inventors have attempted to use a stepped punch, mold the end surface of the tooth by a lower punch, and mold the first plane of the back yoke by the punch. Thereby, the first curved surface portion can be formed at the corner portion of the tooth and the back yoke, and compared with the conventional iron core described above, it is found that the magnetic flux leakage of the iron core generated at the corner portion of the tooth and the back yoke can be reduced. The reason is that, by forming the first curved surface portion at the corner portion of the tooth and the back yoke, the magnetic flux leakage taking a short cut between the peripheral surface of the tooth and the first plane of the back yoke is reduced. Further, by using the iron core having the first curved surface portion at the corner portion of the tooth and the back yoke for an axial gap type rotating electric machine, torque reduction and the loss of the iron core caused by the magnetic flux leakage can be suppressed. Therefore, by having the first curved surface portion, the magnetic characteristics of the iron core can be improved, and further the efficiency of the rotating electric machine can be increased.

[0047] The present application has been made based on the above insight. First, an embodiment of the present application is described.

[0048] (1) An iron core according to an embodiment of the present application is used in an axial gap type rotating electric machine,

[0049] The iron core has:

[0050] a back yoke in a ring shape; and

[0051] a plurality of teeth protruding in an axial direction perpendicular to a first plane of the back yoke,

[0052] the plurality of teeth are provided at intervals in a circumferential direction of the first plane,

[0053] the back yoke and the teeth are composed of a powder compact integrally molded,

[0054] a first curved surface portion connecting between a peripheral surface of the tooth and the first plane of the back yoke is provided at a corner portion of the tooth and the back yoke,

[0055] The first curved portion has a radius of curvature of 0.2 mm or more and 1.5 mm or less.

[0056] The core of the present application described above can reduce leakage flux generated at the tooth and the corner portion of the back yoke by having the first curved portion at the tooth and the corner portion of the back yoke. Thus, the core described above can improve magnetic characteristics. The first curved portion has a radius of curvature of 0.2 mm or more, and thus leakage flux can be effectively reduced. In addition, the first curved portion has a radius of curvature of 1.5 mm or less, and thus the space for the coil arranged at the tooth can be ensured, and the increase in the coil space factor can be achieved. Thus, the reduction in the number of turns of the coil can be suppressed, and thus the reduction in the torque of the rotary electric machine can be suppressed.

[0057] (2) As one mode of the core described above,

[0058] The following mode is mentioned, that is,

[0059] has:

[0060] an outer curved portion connecting between the first plane and the outer circumferential surface of the back yoke; and

[0061] an inner curved portion connecting between the first plane and the inner circumferential surface of the back yoke,

[0062] Each of the radius of curvature of the outer curved portion and the inner curved portion is 0.5 mm or more.

[0063] The core described above composed of a compression-molded body is molded by compression of a soft magnetic powder using a mold. Specifically, the case where the tooth is molded by a punch and the back yoke is molded by a die is mentioned. When the core is molded using a mold, stress is easily concentrated at the corner portion of the die, particularly the die, and sometimes cracks occur at the corner portion of the die. The mode described above is such that each of the radius of curvature of the outer curved portion and the inner curved portion of the back yoke is 0.5 mm or more, and thus stress concentration at the corner portion of the die can be alleviated. Thus, the mode described above can suppress the damage of the die. The upper limit of each of the radius of curvature of the outer curved portion and the inner curved portion is not particularly limited, and for example, 5.0 mm or less is mentioned. If each of the radius of curvature of the outer curved portion and the inner curved portion is large, the length of the linear portion of the outer circumferential surface and the inner circumferential surface of the back yoke with respect to the thickness of the back yoke becomes short. If each of the radius of curvature of the outer curved portion and the inner curved portion is 5.0 mm or less, the length of the linear portion of the outer circumferential surface and the inner circumferential surface of the back yoke can be easily ensured.

[0064] (3) As one mode of the core described in the above (2),

[0065] The following is mentioned: the radius of curvature of the outer curved portion and the radius of curvature of the inner curved portion are different.

[0066] The curvature radius of the outer curved surface portion and the inner curved surface portion of the back yoke can be different. In the case where the curvature radius of the outer curved surface portion and the inner curved surface portion is different, it is preferable that the curvature radius of the outer curved surface portion be made larger than the curvature radius of the inner curved surface portion. In the case where the above-described core is molded using a mold, there is a tendency that the stress of the outer edge corner of the mold that molds the corner of the outer periphery of the back yoke is higher than the stress of the inner edge corner of the mold that molds the corner of the inner periphery of the back yoke. In the case where the curvature radius of the outer curved surface portion is larger than the curvature radius of the inner curved surface portion, the stress concentration at the outer edge corner of the mold can be effectively alleviated. Thus, the above-described mode easily suppresses the damage of the mold. In the case where the above-described core is used to configure a rotary electric machine, there is a tendency that the magnetic flux easily flows at the inner periphery side of the back yoke than at the outer periphery side. The curvature radius of the outer curved surface portion is larger than the curvature radius of the inner curved surface portion, and thus the effective magnetic path area of the back yoke can be easily ensured. As a result, the concentration of the magnetic flux at the inner periphery side of the back yoke can be suppressed, and further, the effect of increasing the torque and the efficiency of the rotary electric machine can be expected.

[0067] (4) As one mode of the above-described core,

[0068] The following mode is exemplified, in which

[0069] In at least one of the outer peripheral surface and the inner peripheral surface of the back yoke, a straight portion extending in the axial direction is provided,

[0070] The length of the straight portion is greater than or equal to 15% of the thickness of the back yoke.

[0071] In the case where the above-described core is housed in a housing to configure a rotary electric machine, the outer peripheral surface of the back yoke is sometimes fitted to the inner peripheral surface of the housing. In the case where the outer peripheral surface of the back yoke has a straight portion, the straight portion of the outer peripheral surface is in surface contact with the inner peripheral surface of the housing, and thus the core is easily fixed with respect to the housing. In the case where the above-described core is used to configure a rotary electric machine, a bus bar that connects the coil wires is sometimes installed at the inner side of the back yoke. In the case where the inner peripheral surface of the back yoke has a straight portion, the straight portion of the inner peripheral surface is in surface contact with the bus bar, and thus the bus bar is easily fixed with respect to the core. The above-described mode is a mode in which the length of the straight portion of at least one of the outer peripheral surface and the inner peripheral surface of the back yoke is greater than or equal to 15% of the thickness of the back yoke, and thus the assembly of the housing and the bus bar with respect to the core becomes easy. In the outer peripheral surface and the inner peripheral surface of the back yoke, the upper limit of the ratio of the length of the straight portion to the thickness of the back yoke is not particularly limited, and for example, a mode in which the ratio is less than or equal to 75% of the thickness of the back yoke is exemplified. The length of the straight portion is exemplified, for example, as being greater than or equal to 0.5 mm and less than or equal to 9 mm. The thickness of the back yoke is exemplified, for example, as being greater than or equal to 1.5 mm and less than or equal to 10 mm.

[0072] (5) As one mode of the above-described core,

[0073] The following is given as an example: the difference between the radial dimension from the shaft center of the rear yoke to the outer peripheral surface and the radial dimension from the shaft center of the rear yoke to the surface of the tooth on the outer peripheral side is less than or equal to 6.0 mm.

[0074] In the rear yoke, the region from the outer peripheral surface of the rear yoke to the portion protruding from the tooth is set as the outer peripheral region. When the above-described core molded from the mold is taken out, sometimes bending stress acts on the outer peripheral region of the rear yoke. Sometimes the outer peripheral region is deformed due to this stress. The smaller the radial dimension of the outer peripheral region in the rear yoke, the easier it is to suppress deformation of the outer peripheral region due to stress at the time of taking out from the mold. The above-described manner is that the difference between the radial dimension from the shaft center of the rear yoke to the outer peripheral surface and the radial dimension from the shaft center of the rear yoke to the surface of the tooth on the outer peripheral side is less than or equal to 6.0 mm. Thereby, the radial dimension of the outer peripheral region in the rear yoke is made small, and deformation of the outer peripheral region can be suppressed. Hereinafter, sometimes the radial dimension from the shaft center of the rear yoke to the outer peripheral surface is referred to as the "outer radius of the rear yoke". Sometimes the radial dimension from the shaft center of the rear yoke to the surface of the tooth on the outer peripheral side is referred to as the "outer radius of the tooth".

[0075] In addition, if the difference between the outer radius of the rear yoke and the outer radius of the tooth is less than or equal to 6.0 mm, the compression area at the time of molding the core using the mold becomes small. Therefore, a high molding pressure can be applied, and thus the core can be densified. The difference between the outer radius of the rear yoke and the outer radius of the tooth is further given as less than or equal to 4.0 mm, less than or equal to 3.0 mm.

[0076] (6) As one example of the above-described core,

[0077] The following is given as an example: the difference between the radial dimension from the shaft center of the rear yoke to the surface of the tooth on the inner peripheral side and the radial dimension from the shaft center of the rear yoke to the inner peripheral surface is less than or equal to 7.0 mm.

[0078] In the rear yoke, a region from the inner peripheral surface of the rear yoke to a portion protruding from the tooth is set as an inner peripheral region. When the above-described core molded by the mold is taken out, a bending stress is sometimes applied to the inner peripheral region of the rear yoke. The inner peripheral region is sometimes deformed due to the stress. The smaller the radial dimension of the inner peripheral region in the rear yoke, the easier it is to suppress deformation of the inner peripheral region due to the stress at the time of taking out from the mold. The above-described mode is a mode in which the difference between the radial dimension from the axial center of the rear yoke to the surface of the tooth on the inner peripheral side and the radial dimension from the axial center of the rear yoke to the inner peripheral surface is less than or equal to 7.0 mm. Thus, the radial dimension of the inner peripheral region in the rear yoke is small, and it is possible to suppress deformation of the inner peripheral region. Hereinafter, the radial dimension from the axial center of the rear yoke to the surface of the tooth on the inner peripheral side is sometimes referred to as the "inner radius of the tooth". The radial dimension from the axial center of the rear yoke to the inner peripheral surface is sometimes referred to as the "inner radius of the rear yoke".

[0079] In addition, if the difference between the inner radius of the tooth and the inner radius of the rear yoke is less than or equal to 7.0 mm, the compression area at the time of molding the core using the mold is small. Therefore, it is possible to apply a high molding pressure, and thus it is possible to densify the core. The difference between the inner radius of the tooth and the inner radius of the rear yoke is further exemplified as being less than or equal to 5.0 mm below, less than or equal to 4.0 mm.

[0080] (7) As one mode of the above-described core,

[0081] Exemplified is a mode in which a protruding portion protruding in the radial direction or a recessed portion recessed in the radial direction is provided locally at at least one of the outer peripheral surface and the inner peripheral surface of the rear yoke.

[0082] In a case where a rotary electric machine is configured using the above-described core, the above-described mode is a mode in which the outer peripheral surface of the rear yoke has a protruding portion or a recessed portion, and thus the protruding portion or the recessed portion can be used for positioning with respect to the housing. For example, a protruding portion or a recessed portion is provided in advance on the outer peripheral surface of the rear yoke, and a recessed portion or a protruding portion corresponding to the protruding portion or the recessed portion is provided in advance on the inner peripheral surface of the housing. By fitting these protruding portion and recessed portion, it is possible to position the core with respect to the housing. In addition, in a case where a rotary electric machine is configured using the above-described core, the above-described bus bar is sometimes arranged inside the rear yoke. The inner peripheral surface of the rear yoke has a protruding portion or a recessed portion, and thus the protruding portion or the recessed portion can be used for positioning of the bus bar. For example, a protruding portion or a recessed portion is provided in advance on the inner peripheral surface of the rear yoke, and a recessed portion or a protruding portion corresponding to the protruding portion or the recessed portion is provided in advance on the bus bar. By fitting these protruding portion and recessed portion, it is possible to position the bus bar with respect to the core.

[0083] (8) As one mode of the above-described core,

[0084] Exemplified is a mode in which a protruding portion protruding in the radial direction or a recessed portion recessed in the radial direction is provided locally at at least one of the outer peripheral surface and the inner peripheral surface of the rear yoke.

[0085] The powder compact is composed of a collection of soft magnetic particles having an insulating coating on the surface of the soft magnetic particles,

[0086] The soft magnetic particles are iron-based particles composed of pure iron or at least one iron-based alloy selected from the group consisting of Fe-Si-based alloys, Fe-Al-based alloys, Fe-Cr-Al-based alloys, and Fe-Cr-Si-based alloys.

[0087] Pure iron or the above-mentioned iron-based alloy is a relatively soft material. Therefore, the soft magnetic particles are iron-based particles composed of pure iron or the above-mentioned iron-based alloy, whereby the soft magnetic particles are easily deformed when the powder compact is formed. Thus, the above-mentioned mode is a powder compact having high density and high dimensional accuracy. By densifying the powder compact, the mechanical strength and magnetic characteristics of the core can be improved. In addition, the soft magnetic particles have an insulating coating on the surface thereof, whereby the electrical insulation between the soft magnetic particles can be improved. Therefore, the core loss caused by eddy current loss can be reduced.

[0088] (9) As one mode of the core described in the above (8),

[0089] Examples include: the insulating coating contains a phosphate coating.

[0090] The phosphate coating has high adhesion to the iron-based particles, and is also excellent in deformability. Therefore, the insulating coating contains a phosphate coating, whereby the insulating coating easily follows the deformation of the iron-based particles when the powder compact is formed. Thus, the above-mentioned mode is a mode in which the insulating coating is less likely to be damaged, and the core loss can be reduced.

[0091] (10) As one mode of the core,

[0092] Examples include: the relative density of the powder compact is greater than or equal to 90%.

[0093] The above-mentioned mode is a mode in which the relative density of the powder compact is greater than or equal to 90%, whereby the density of the powder compact is high. By densifying the powder compact, the mechanical strength and magnetic characteristics of the core can be improved.

[0094] (11) A core according to an embodiment of the present invention is used in an axial gap type rotary electric machine,

[0095] The core has:

[0096] a ring-shaped back yoke; and

[0097] a plurality of teeth that protrude in an axial direction perpendicular to a first plane of the back yoke,

[0098] The plurality of teeth are arranged at intervals in a circumferential direction of the first plane,

[0099] the rear yoke and the teeth are composed of a powder compact formed integrally,

[0100] the teeth and the corner portion of the rear yoke have a first curved surface portion connecting between the peripheral surface of the teeth and the first plane of the rear yoke,

[0101] the radius of curvature of the first curved surface portion is greater than or equal to 0.2 mm and less than or equal to 1.5 mm,

[0102] the core has:

[0103] an outer curved surface portion connecting between the first plane and the outer peripheral surface of the rear yoke; and

[0104] an inner curved surface portion connecting between the first plane and the inner peripheral surface of the rear yoke,

[0105] the radius of curvature of each of the outer curved surface portion and the inner curved surface portion is greater than or equal to 0.5 mm,

[0106] at least one of the outer peripheral surface and the inner peripheral surface of the rear yoke has a straight portion extending in the axial direction,

[0107] the length of the straight portion is greater than or equal to 15% of the thickness of the rear yoke.

[0108] The core of the present application described above has a first curved surface portion at the corner portion of the teeth and the rear yoke, whereby the magnetic flux leakage generated at the corner portion of the teeth and the rear yoke can be reduced. Thus, the core described above can improve the magnetic characteristics. In particular, the radius of curvature of the first curved surface portion is greater than or equal to 0.2 mm, whereby the magnetic flux leakage can be effectively reduced. In addition, the radius of curvature of the first curved surface portion is less than or equal to 1.5 mm, whereby the space for the coil arranged in the teeth can be ensured, and the increase in the coil space factor can be achieved. Thus, the reduction in the number of turns of the coil can be suppressed, and therefore the reduction in the torque of the rotary electric machine can be suppressed.

[0109] In addition, as explained by the means described in the above (2), the radius of curvature of each of the outer curved surface portion and the inner curved surface portion of the rear yoke is greater than or equal to 0.5 mm, whereby the stress concentration at the corner portion of the mold can be alleviated. Thus, the core described above can suppress the damage to the mold.

[0110] Further, as explained by the means described in the above (4), the length of the straight portion of at least one of the outer peripheral surface and the inner peripheral surface of the rear yoke is greater than or equal to 15% of the thickness of the rear yoke, whereby the assembly of the housing, the bus bar, and the core becomes easy.

[0111] (12) The stator according to the embodiment of the present application is a stator of a rotary electric machine of an axial gap type, and has:

[0112] The core according to any one of (1) to (11) above; and

[0113] A coil is arranged in each tooth of the core.

[0114] The stator is excellent in magnetic characteristics of the core. This is because the core according to the embodiment is excellent in magnetic characteristics of the core.

[0115] (13) The rotating electric machine according to the embodiment has a rotor and a stator, and is an axial gap type rotating electric machine in which the rotor and the stator are arranged in opposition to each other in an axial direction,

[0116] In the rotating electric machine, the stator is the stator according to (12) above.

[0117] The rotating electric machine is excellent in efficiency. This is because the stator according to the embodiment is excellent in magnetic characteristics of the core.

[0118] [Details of the Embodiment of the Invention]

[0119] Hereinafter, a specific example of the core, the stator, and the rotating electric machine according to the embodiment of the invention will be described with reference to the drawings. The same reference numerals in the drawings denote the same names. In addition, the invention is not limited to these examples, but is shown by the claims, and includes all modifications within the meaning and the scope equivalent to the claims.

[0120] <Core>

[0121] Reference Figures 1-3 A core 1 according to the embodiment will be described. The core 1 is used in an axial gap type rotating electric machine. The core 1 has a ring-shaped back yoke 2 and a plurality of teeth 3 protruding from the back yoke 2. One of the features of the core 1 is that, as shown in Figure 2 , Figure 3 a first curved surface portion 31 is provided at a corner of the tooth 3 and the back yoke 2. In the following description, when the core 1 is described, the tooth 3 protruding side is set as the upper side, and the opposite side thereof is set as the lower side.

[0122] (back yoke)

[0123] Figure 1 The back yoke 2 shown is a circular ring plate. As shown in Figure 2 , in the back yoke 2, one flat surface thereof, that is, the upper surface is set as a first flat surface 21, and the surface opposite to the first flat surface 21, that is, the lower surface is set as a second flat surface 22. The tooth 3 is provided protruding from the first flat surface 21 of the back yoke 2 as shown in Figure 2 . The thickness of the back yoke 2 is, for example, greater than or equal to 1.5 mm and less than or equal to 10 mm, more preferably greater than or equal to 2.0 mm and less than or equal to 7.0 mm. In Figure 2In this example, the thickness of the rear yoke 2 is represented by T2. The first plane 21 and the second plane 22 are planes in directions orthogonal to the axis of the rear yoke 2.

[0124] In the rear yoke 2, at the corner of the outer periphery of the first plane 21, as... Figure 2 As shown, an outer curved surface 23 connects the outer peripheral surfaces of the first plane 21 and the rear yoke 2. The outer curved surface 23 is an arc tangent to the extended surface of the first plane 21 and the outer peripheral surface of the rear yoke 2; in other words, it is an arc convex toward the line of intersection of the two extended surfaces. Additionally, an inner curved surface 24 connects the inner peripheral surfaces of the first plane 21 and the rear yoke 2 at the corner of the inner peripheral edge of the first plane 21. The inner curved surface 24 is an arc tangent to the extended surface of the first plane 21 and the inner peripheral surface of the rear yoke 2; in other words, it is an arc convex toward the line of intersection of the two extended surfaces. The radius of curvature of each of the outer curved surface 23 and the inner curved surface 24 is preferably greater than or equal to 0.5 mm, more preferably greater than or equal to 1.0 mm, and more preferably greater than or equal to 1.5 mm. The upper limit of the radius of curvature of each of the outer curved surface 23 and the inner curved surface 24 is, for example, less than or equal to 5.0 mm, more preferably less than or equal to 4.0 mm, and more preferably less than or equal to 3.0 mm. Furthermore, the radii of curvature of the outer curved surface 23 and the inner curved surface 24 are preferably greater than or equal to 10% and less than or equal to 85% of the thickness of the rear yoke 2, more preferably greater than or equal to 20% and less than or equal to 60%. The radii of curvature of the outer curved surface 23 and the inner curved surface 24 may be the same or different. Figure 2 In the middle, the radius of curvature of the outer curved surface 23 is the same as that of the inner curved surface 24.

[0125] The radii of curvature of the outer curved surface 23 and the inner curved surface 24 are greater than or equal to 0.5 mm, which helps to alleviate stress concentration at the corners of the mold when forming the core 1 using the mold. This helps to prevent damage to the mold. The reasons for this will be explained later. Furthermore, if the radii of curvature of the outer curved surface 23 and the inner curved surface 24 are less than or equal to 5.0 mm, it is easier to ensure the length of the straight portions 25 and 26 on the outer and inner circumferential surfaces of the rear yoke 2. This is because if the radii of curvature of the outer curved surface 23 or the inner curved surface 24 are increased, the length of the straight portions 25 and 26 on the outer or inner circumferential surfaces becomes shorter relative to the thickness of the rear yoke 2.

[0126] When the radii of curvature of the outer curved surface 23 and the inner curved surface 24 are different, it is preferable to set the radius of curvature of the outer curved surface 23 to be larger than that of the inner curved surface 24. When forming the core 1 using a mold, there is a tendency that the stress at the outer corner of the mold forming the outer periphery of the rear yoke 2 is higher than the stress at the inner corner of the mold forming the inner periphery of the rear yoke 2. When the radius of curvature of the outer curved surface 23 is larger than that of the inner curved surface 24, stress concentration at the outer corner of the mold can be effectively mitigated. This makes it easier to prevent mold damage.

[0127] Preferably, at least one of the outer and inner peripheral surfaces of the rear yoke 2 has a straight portion extending axially. In this example, the outer and inner peripheral surfaces have straight portions 25 and 26. The length of the straight portions 25 and 26 is preferably greater than or equal to 15% of the thickness of the rear yoke 2, and more preferably greater than or equal to 25%.

[0128] When the iron core 1 is housed within the housing, sometimes the outer peripheral surface of the rear yoke 2 is fitted into the inner peripheral surface of the housing. When the outer peripheral surface of the rear yoke 2 has a straight portion 25, the straight portion 25 makes surface contact with the inner peripheral surface of the housing, thereby facilitating the fixing of the iron core 1 relative to the housing. Furthermore, when using the iron core 1 to construct a rotary motor, sometimes a busbar is provided inside the rear yoke 2. When the inner peripheral surface of the rear yoke 2 has a straight portion 26, the straight portion 26 makes surface contact with the busbar, thereby facilitating the fixing of the busbar relative to the iron core 1. The length of the straight portions 25 and 26 is greater than or equal to 15% of the thickness of the rear yoke 2, thereby facilitating the assembly of the housing and the busbar relative to the iron core 1. The upper limit of the ratio of the length of the straight portions 25 and 26 to the thickness of the rear yoke 2 is, for example, less than or equal to 90% of the thickness of the rear yoke 2, and further less than or equal to 80%. The length of the straight portions 25 and 26 is, for example, greater than or equal to 0.5 mm and less than or equal to 9 mm, and further greater than or equal to 0.8 mm and less than or equal to 8.0 mm.

[0129] (tooth)

[0130] Tooth 3 Figure 1 As shown, the first plane 21 of the rear yoke 2 is arranged at circumferential intervals. The teeth 3 are as follows... Figure 2 As shown, the tooth 3 protrudes axially from the first plane 21 on the rear yoke 2. Specifically, the tooth 3 protrudes in a direction perpendicular to the first plane 21. The number of teeth 3 can be appropriately determined, for example, greater than or equal to 3, and further greater than or equal to 6. In this example, as... Figure 1 As shown, nine teeth 3 are arranged at equal intervals in the circumferential direction. Furthermore, the shape of the teeth 3 is not particularly limited; for example, it can be cylindrical, polygonal, or various other shapes. In this example, the shape of the teeth 3 is a triangular prism. The shape of the teeth 3 can also be a trapezoidal prism, a quadrangular prism, or the like.

[0131] As shown in FIG. 3, the tooth 3 has a first curved surface portion 31 connecting between the peripheral surface of the tooth 3 and the first plane 21 of the back yoke 2. Figure 2 Figure 3 The curvature radius of the first curved surface portion 31 is greater than or equal to 0.2 mm and less than or equal to 1.5 mm, preferably greater than or equal to 0.3 mm, further greater than or equal to 0.4 mm and less than or equal to 1.2 mm. By having the first curved surface portion 31, the root side of the tooth 3 connected to the back yoke 2 is formed so that the peripheral surface of the tooth 3 expands toward the first plane 21. The portion of the peripheral surface of the tooth 3 other than the first curved surface portion 31 is formed in a linear shape in the axial direction of the tooth 3.

[0132] As shown in FIG. 3, the tooth 3 has a first curved surface portion 31 connecting between the peripheral surface of the tooth 3 and the first plane 21 of the back yoke 2. Figure 3 The coil 110 is arranged in the peripheral surface of the tooth 3. The current flows in the coil 110, and the magnetic flux flows through the core 1 to form a magnetic circuit. The curvature radius of the first curved surface portion 31 is greater than or equal to 0.2 mm, and thus the leakage magnetic flux generated at the corner of the tooth 3 and the back yoke 2 can be reduced. In addition, the curvature radius of the first curved surface portion 31 is less than or equal to 1.5 mm, and thus the space for the coil 110 arranged in the tooth 3 can be easily ensured. Therefore, the reduction in the number of turns of the coil 110 can be suppressed.

[0133] In order to ensure the electrical insulation between the core 1 and the coil 110, an insulating coating film not shown can be applied to the surface of the core 1. The insulating coating film can be formed by applying a resin having electrical insulation. As the resin constituting the insulating coating film, for example, an epoxy resin-based resin, a fluorine-based resin, a polyimide-based resin, or the like can be mentioned. The insulating coating film can be provided on at least the surface of the core 1 in contact with the coil 110. For example, the case where the insulating coating film is provided on the peripheral surface of the tooth 3 and the first plane 21 of the back yoke 2 can be mentioned. In addition, an insulator not shown can be interposed between the core 1 and the coil 110.

[0134] In the core 1, the difference between the outer radius of the back yoke 2 and the outer radius of the tooth 3 is preferably greater than or equal to 0 mm and less than or equal to 6.0 mm, further preferably less than or equal to 4.0 mm, and more preferably less than or equal to 3.0 mm. The outer radius of the back yoke 2 refers to the radial dimension from the axial center of the back yoke 2 to the outer peripheral surface. In addition, the outer radius of the tooth 3 refers to the radial dimension from the axial center of the back yoke 2 to the surface of the tooth 3 on the outer peripheral side. In Figure 1 the outer radius of the back yoke 2 is denoted by R20, and the outer radius of the tooth 3 is denoted by R30. The difference between the outer radius of the back yoke 2 and the outer radius of the tooth 3 (R20-R30) is less than or equal to 6.0 mm, and thus the magnetic flux generated in the core 1 can be easily guided to the coil 110. Figure 3 ​As shown, the radial dimension of the outer peripheral region 27 in the back yoke 2 is made small. The outer peripheral region 27 of the back yoke 2 refers to a region from the outer peripheral surface of the back yoke 2 to the portion protruding from the tooth 3. The smaller the radial dimension of the outer peripheral region 27 in the back yoke 2, the more the bending stress acting on the outer peripheral region 27 at the time of taking out the molded core 1 from the mold can be reduced. The reason for this will be described later. Thus, the difference between the outer radius R20 of the back yoke 2 and the outer radius R30 of the tooth 3 is made smaller than or equal to 6.0 mm, further smaller than or equal to 4.0 mm, whereby deformation of the outer peripheral region 27 caused by stress at the time of taking out from the mold can be suppressed.

[0135] In addition, if the difference between the outer radius R20 of the back yoke 2 and the outer radius R30 of the tooth 3 is made smaller than or equal to 6.0 mm, further smaller than or equal to 3.0 mm, the compression area at the time of molding the core using the mold becomes small. Thus, a high molding pressure can be applied, and thus the core 1 can be densified. The reason for this will be described later.

[0136] In the core 1, it is preferable that the difference between the inner radius of the tooth 3 and the inner radius of the back yoke 2 be larger than or equal to 0 mm and smaller than or equal to 7.0 mm, further preferably smaller than or equal to 5.0 mm, and more preferably smaller than or equal to 4.0 mm. The inner radius of the tooth 3 refers to the radial dimension from the axial center of the back yoke 2 to the surface on the inner peripheral side of the tooth 3. In addition, the inner radius of the back yoke 2 refers to the radial dimension from the axial center of the back yoke 2 to the inner peripheral surface. In Figure 1 In the core 1, it is preferable that the difference between the inner radius of the tooth 3 and the inner radius of the back yoke 2 be larger than or equal to 0 mm and smaller than or equal to 7.0 mm, further preferably smaller than or equal to 5.0 mm, and more preferably smaller than or equal to 4.0 mm. The inner radius of the tooth 3 refers to the radial dimension from the axial center of the back yoke 2 to the surface on the inner peripheral side of the tooth 3. In addition, the inner radius of the back yoke 2 refers to the radial dimension from the axial center of the back yoke 2 to the inner peripheral surface. In Figure 3 As shown, the radial dimension of the inner peripheral region 28 in the back yoke 2 is made small. The inner peripheral region 28 of the back yoke 2 refers to a region from the inner peripheral surface of the back yoke 2 to the portion protruding from the tooth 3. The smaller the radial dimension of the inner peripheral region 28 in the back yoke 2, the more the bending stress acting on the inner peripheral region 28 at the time of taking out the molded core 1 from the mold can be reduced. The reason for this will be described later. Thus, the difference between the inner radius R31 of the tooth 3 and the inner radius R21 of the back yoke 2 is made smaller than or equal to 7.0 mm, further smaller than or equal to 5.0 mm, whereby deformation of the inner peripheral region 28 caused by stress at the time of taking out from the mold can be suppressed.

[0137] In addition, if the difference between the inner radius R31 of the tooth 3 and the inner radius R21 of the back yoke 2 is made smaller than or equal to 7.0 mm, further smaller than or equal to 4.0 mm, the compression area at the time of molding the core using the mold becomes small. Thus, a high molding pressure can be applied, and thus the core 1 can be densified. The reason for this will be described later.

[0138] The difference between the position of the end face of the highest tooth 3 and the position of the end face of the lowest tooth 3 among the multiple teeth 3 of the iron core 1 is preferably less than or equal to 0.2 mm. The position of the end face of the tooth 3 is as follows: Figure 2 As shown, H3 refers to the axial height position from the second plane 22 (lower surface) of the rear yoke 2 to the end face of the tooth 3 when the second plane 22 of the rear yoke 2 is placed on a plane. The difference between the position of the end face of the highest tooth 3 and the position of the end face of the lowest tooth 3 is less than or equal to 0.2 mm, thus minimizing the height fluctuation of each end face of the tooth 3. As described later, this is achieved using the iron core 1. Figure 12 In the case of the rotary motor 300 shown, each end face of the tooth 3 is arranged opposite to the magnet 220 of the rotor 200. The height fluctuation of each end face of the tooth 3 is small, thereby reducing the fluctuation of the gap between each end face of the tooth 3 and the rotor 200 in the rotary motor 300. As a result, cogging effect and other issues can be reduced, and the degradation of the characteristics of the rotary motor 300 can be suppressed.

[0139] (Powder-pressed molded body)

[0140] The rear yoke 2 and the tooth 3 are formed by a single-piece pressed powder molding body. That is, the iron core 1 is formed by pressing powder molding body. The pressed powder molding body is formed by compressing soft magnetic powder. Soft magnetic powder is an aggregate of multiple soft magnetic particles with an insulating coating on their surface. In other words, the pressed powder molding body is an aggregate of multiple soft magnetic particles. In this example, the pressed powder molding body constituting the iron core 1 is essentially composed only of soft magnetic powder, which consists of soft magnetic particles.

[0141] Examples of soft magnetic particles include iron-based particles composed of pure iron with a purity greater than or equal to 99% by mass, or at least one iron-based alloy selected from Fe-Si alloys, Fe-Al alloys, Fe-Cr-Al alloys, and Fe-Cr-Si alloys. Pure iron or the aforementioned iron-based alloys are relatively soft materials. Therefore, since the soft magnetic particles are made of pure iron or the aforementioned iron-based alloys, they are easily deformed during the molding of the powder-pressed body constituting the core 1. As a result, a powder-pressed body with high dimensional accuracy is obtained at a high density. By increasing the density of the powder-pressed body, the mechanical strength and magnetic properties of the core 1 can be improved. In addition, the surface of the soft magnetic particles has an insulating coating, thereby improving the electrical insulation between the soft magnetic particles. Therefore, the iron loss of the core 1 caused by eddy current losses can be reduced. Examples of insulating coatings include phosphate coatings and silica coatings. The insulating coating preferably includes a phosphate coating. Phosphate coatings exhibit high adhesion to iron-based particles and excellent deformability. Therefore, the insulating film includes a phosphate coating, which facilitates the following of the deformation of the iron-based particles during the molding of the powder compact. Consequently, the insulating coating is less prone to damage, reducing iron loss in the core 1.

[0142] The relative density of the pressed powder molded body constituting the iron core 1 is preferably greater than or equal to 90%. By increasing the density of the pressed powder molded body, the mechanical strength and magnetic properties of the iron core 1 can be improved. More preferably, the relative density is greater than or equal to 93%. Relative density refers to the ratio (%) of the actual density of the pressed powder molded body to its true density. The true density of the pressed powder molded body can be determined based on the true density of the soft magnetic powder. For example, the relative density of the pressed powder molded body can be calculated as [(molded density of the pressed powder molded body / true density of the pressed powder molded body) × 100]. The molded density of the pressed powder molded body can be obtained by immersing the pressed powder molded body in oil, thereby impregnating it with oil, and by calculating [oil-containing density × (mass of the pressed powder molded body before oil impregnation / mass of the pressed powder molded body after oil impregnation)]. The oil-containing density is the value obtained by dividing the mass of the pressed powder molded body after oil impregnation by its volume. The volume of the pressed powder molded body can be representatively measured using the liquid displacement method.

[0143] <Mold>

[0144] The iron core 1, which is composed of compressed powder, is formed by compressing soft magnetic powder using a mold, and thus can be manufactured. Below, refer to... Figures 4-10 The mold 5 used in the manufacture of the iron core 1 will be described below. Mold 5 is as follows... Figure 4 As shown, it has: a die 50; a mandrel 60 disposed within the die 50; and upper and lower punches 70 and 80, which are fitted into the die 50.

[0145] The die 50 is a stepped die. The die 50, as shown in Figure 5 , Figure 6 , includes a first molding portion 51 and a plurality of second molding portions 52, and has a stepped portion 53 between the first molding portion 51 and the second molding portions 52. The first molding portion 51 is a portion of a space in which the back yoke 2 shown in Figure 1 , Figure 2 is molded. The second molding portion 52 is a portion of a space in which the tooth 3 shown in Figure 1 , Figure 2 is molded. The first molding portion 51 is provided on the upper side of the die 50. The second molding portion 52 is provided continuously with the first molding portion 51 on the lower side of the die 50. The core rod 60 is disposed coaxially within the first molding portion 51 of the die 50. The upper punch 70 is located on the upper side of the die 50 and is fitted from above with the first molding portion 51. The lower punch 80 is located on the lower side of the die 50 and is fitted from below with the second molding portion 52. The lower punch 80, as shown in Figure 8 , Figure 9 , has a plurality of punch portions 82 inserted into the second molding portion 52 shown in Figure 5 , Figure 6 on the front end side thereof. The base end side of the punch portion 82 is integrally formed.

[0146] In the mold 5 shown in Figure 4 , a ring-shaped space in which the back yoke 2 shown in Figure 1 , Figure 2 is molded is formed by the first molding portion 51 of the die 50, the core rod 60, and the upper punch 70. In addition, a columnar space in which the tooth 3 shown in Figure 1 , Figure 2 is molded is formed by the second molding portion 52 of the die 50 and the punch portions 82 of the lower punch 80. In molding the core 1 using the mold 5, the core rod 60 is disposed within the first molding portion 51 of the die 50, and each punch portion 82 of the lower punch 80 is inserted into each second molding portion 52. In this state, a raw material powder not shown is filled into the first molding portion 51 and the second molding portions 52. Then, the upper punch 70 is lowered, and the raw material powder is pressed by the upper punch 70 from the upper side of the first molding portion 51. As shown in Figure 10As shown, when the iron core 1 is formed using the mold 5, the inner circumference of the first forming part 51 forms the outer circumference of the rear yoke 2, and the first plane 21 facing the rear yoke 2 is formed by the step part 53. The outer circumference of the mandrel 60 forms the inner circumference of the rear yoke 2. The end face of the upper punch 70 forms the second plane 22 of the rear yoke 2. Additionally, the inner circumference of the second forming part 52 forms the circumferential surface of the tooth 3. The end face of the punch head 82 of the lower punch 80 forms the end face of the tooth 3. On the other hand, when the formed iron core 1 is removed from the mold 5, the upper punch 70 is raised, and the die 50 and mandrel 60 are lowered relative to the lower punch 80. Then, the iron core 1 is pulled out from the die 50 while the end face of the tooth 3 is supported by the punch head 82.

[0147] The raw material powder is mainly composed of soft magnetic powder. "Main component" refers to the component that, when the raw material powder is set at 100% by mass, contains 90% or more by mass. Lubricants, adhesive resins, etc., can be added to the raw material powder as needed.

[0148] The average particle size of the soft magnetic powder is, for example, set to be greater than or equal to 20 μm and less than or equal to 300 μm, and further set to be greater than or equal to 40 μm and less than or equal to 250 μm. By setting the average particle size of the soft magnetic powder within the above range, it is easy to operate and easy to compress and mold. The average particle size of the soft magnetic powder refers to the particle size that, when measured using a laser diffraction-scattering particle size distribution measuring device, represents 50% of the total mass of all particles.

[0149] By increasing the molding pressure when compressing the raw material powder containing soft magnetic powder, the core 1 can be made denser. For example, the molding pressure is set to be greater than or equal to 700 MPa, and more specifically, greater than or equal to 800 MPa.

[0150] like Figure 7 As shown, in the die 50, the first corner 531 between the surface of the stepped portion 53 and the inner peripheral surface of the second forming portion 52 is formed to... Figure 2 The first curved surface 31 of the iron core 1 shown corresponds to the curved surface shape. The radius of curvature of the first corner 531 is greater than or equal to 0.2 mm and less than or equal to 1.5 mm. The first corner 531 is formed into a curved surface shape, thereby forming the first curved surface 31 at the corner of the tooth 3 and the rear yoke 2.

[0151] In addition, such as Figure 7 As shown, the outer corner 532 and inner corner 533 of the stepped portion 53 are formed with... Figure 2The outer curved surface portion 23 and the inner curved surface portion 24 of the rear yoke 2 are curved in correspondence with each other. The radius of curvature of each of the outer corner portion 532 and the inner corner portion 533 is, for example, greater than or equal to 0.5 mm and less than or equal to 5.0 mm. The outer corner portion 532 and the inner corner portion 533 are curved, whereby the outer curved surface portion 23 and the inner curved surface portion 24 are formed at the corners of the outer periphery and the inner periphery of the rear yoke 2.

[0152] When the core 1 is molded by pressing the raw material powder with the upper punch 70, as shown in FIG. 6, the second plane 22 of the rear yoke 2 pressed by the end surface of the upper punch 70 becomes a compression surface. At this time, the surface of the step portion 53 and the end surface of the punch portion 82 of the lower punch 80 become pressure receiving surfaces. In this case, the pressure acting on the surface of the step portion 53 is received by the outer corner portion 532 and the inner corner portion 533, and thus the bending stress is easily concentrated in the outer corner portion 532 and the inner corner portion 533. The radius of curvature of each of the outer corner portion 532 and the inner corner portion 533 is greater than or equal to 0.5 mm, and thus stress concentration can be alleviated. Thus, the damage to the die 50 can be suppressed. Figure 10

[0153] On the other hand, when the molded core 1 is taken out of the mold 5, only the end surface of the tooth 3 is supported by the punch portion 82, and the core 1 is pushed up and pulled out of the die 50 by lowering the die 50. At this time, the outer peripheral surface of the rear yoke 2 slides on the inner peripheral surface of the first molding portion 51. In addition, the inner peripheral surface of the rear yoke 2 slides on the outer peripheral surface of the core rod 60. Thus, the bending stress acts on the outer peripheral region 27 and the inner peripheral region 28 of the rear yoke 2 extending to the outer side and the inner side in the radial direction of the tooth 3. Figure 3 Figure 1 The difference between the outer radius R20 of the rear yoke 2 and the outer radius R30 of the tooth 3 is less than or equal to 6.0 mm, and thus the radial dimension of the outer peripheral region 27 is small. In addition, the difference between the inner radius R21 of the rear yoke 2 and the inner radius R31 of the tooth 3 is less than or equal to 7.0 mm, and thus the radial dimension of the inner peripheral region 28 is small. Figure 1

[0154] If one of the difference between the outer radius R20 of the rear yoke 2 and the outer radius R30 of the tooth 3 and the difference between the inner radius R31 of the tooth 3 and the inner radius R21 of the rear yoke 2, and preferably both, is less than or equal to 4.0 mm, and further less than or equal to 3.0 mm, the area of the second plane 22 can be reduced. When the core 1 is molded by the mold 5, as shown in FIG. 6, the second plane 22 of the rear yoke 2 pressed by the end surface of the upper punch 70 becomes a compression surface. At this time, the surface of the step portion 53 and the end surface of the punch portion 82 of the lower punch 80 become pressure receiving surfaces. In this case, the pressure acting on the surface of the step portion 53 is received by the outer corner portion 532 and the inner corner portion 533, and thus the bending stress is easily concentrated in the outer corner portion 532 and the inner corner portion 533. The radius of curvature of each of the outer corner portion 532 and the inner corner portion 533 is greater than or equal to 0.5 mm, and thus stress concentration can be alleviated. Thus, the damage to the die 50 can be suppressed. Figure 10 ​​​As shown, the smaller the area of the second plane 22, the smaller the area of the compression surface pressed by the end surface of the upper punch 70. A high molding pressure can be applied in correspondence with the small compression area, and thus the core 1 can be densified. The difference between the outer radius R20 of the back yoke 2 and the outer radius R30 of the tooth 3 can be the same as or different from the difference between the inner radius R31 of the tooth 3 and the inner radius R21 of the back yoke 2. In Figure 1 , Figure 2 In the present embodiment, the difference between the outer radius R20 of the back yoke 2 and the outer radius R30 of the tooth 3 is larger than the difference between the inner radius R31 of the tooth 3 and the inner radius R21 of the back yoke 2. In molding the core 1, the inner peripheral side of the back yoke 2 and the tooth 3 is less likely to spring back, and the friction against the mold 5 is less likely to occur. Thus, the load applied to the root of the tooth 3 is less likely to occur on the inner peripheral side. As a result, the difference between the inner radius R31 of the tooth 3 and the inner radius R21 of the back yoke 2 can be larger than the difference between the outer radius R20 of the back yoke 2 and the outer radius R30 of the tooth 3.

[0155] <Stator>

[0156] Referring to Figure 11 A stator 100 according to the present embodiment will be described. The stator 100 is used in a rotary electric machine of the axial gap type. The stator 100 has a core 1 and coils 110 arranged on each tooth 3 of the core 1. The coils 110 are formed by winding wire around the teeth 3.

[0157] <Rotary Electric Machine>

[0158] Referring to Figure 12 A rotary electric machine 300 according to the present embodiment will be described. The rotary electric machine 300 can be a motor or a generator. The rotary electric machine 300 has a rotor 200 and a stator 100. The rotary electric machine 300 is a rotary electric machine of the axial gap type in which the rotor 200 and the stator 100 are arranged opposite to each other in the direction of the rotation axis.

[0159] The stator 100 and the rotor 200 are housed in a cylindrical housing 310. Circular plate-shaped plates 320 are attached to both ends of the housing 310. Through-holes are formed in the centers of the two plates 320, and a rotation axis 330 penetrates the housing 310.

[0160] (Rotor)

[0161] The rotor 200 has a plurality of magnets 220 in a flat plate shape and a retaining plate 210 in a circular ring shape that supports the magnets 220. The planar shape of the magnets 220 is a shape that substantially corresponds to the end surface of the tooth 3. In the case where the shape of the end surface of the tooth 3 is a triangular shape, the planar shape of the magnet 220 is, for example, a triangular shape, a trapezoidal shape, and the like. The retaining plate 210 is fixed to the rotating shaft 330 and rotates together with the rotating shaft 330. Each of the magnets 220 is embedded in the retaining plate 210. Each of the magnets 220 can also be fixed to the retaining plate 210 by an adhesive. The magnets 220 are arranged at equal intervals in the circumferential direction of the rotating shaft 330. In addition, the magnets 220 are magnetized in the axial direction of the rotating shaft 330. The magnetization directions of the magnets 220 adjacent in the circumferential direction are opposite to each other.

[0162] (stator)

[0163] The stator 100 is arranged so that the end surface of the tooth 3 opposes the magnet 220 of the rotor 200. The stator 100 is fitted to the inner circumferential surface of the housing 310 with the outer circumferential surface of the back yoke 2 of the iron core 1, and thereby is fixed to the housing 310. In this example, the outer circumferential surface of the back yoke 2 has a straight portion 25, and thus the iron core 1 that constitutes the stator 100 is easily fixed with respect to the housing 310. In addition, a circular ring-shaped bearing 340 that rotatably supports the rotating shaft 330 is arranged on the inner circumferential side of the back yoke 2.

[0164] [modified example]

[0165] In the iron core 1, a convex portion or a concave portion can be provided on at least one of the outer circumferential surface and the inner circumferential surface of the back yoke 2. Referring to Figure 13A and Figure 13B , Figure 14A and Figure 14B , an example in which the outer circumferential surface of the back yoke 2 has a convex portion 41 or a concave portion 42 will be described.

[0166] Figure 13A The iron core 1 illustrated in FIG. 10 has a convex portion 41 protruding in the radial direction on the outer circumferential surface of the back yoke 2. The convex portion 41 is partially provided on the outer circumferential surface of the back yoke 2. In this example, the convex portion 41 is provided on the outer circumferential surface of the back yoke 2 on the side of the tooth 3. Figure 13A In the example illustrated in FIG. 10, a case in which the convex portion 41 is one is shown, but the number of convex portions 41 can be plural. In this example, the shape of the convex portion 41 when viewed from above is a rectangular shape. The shape of the convex portion 41 is not limited to a rectangular shape, and can be, for example, a semicircular shape, a triangular shape, a trapezoidal shape, and the like.

[0167] In the case where the rotating electric machine 300 is configured using the iron core 1 illustrated in FIG. 10, as illustrated in FIG. 11, a concave portion 311 corresponding to the convex portion 41 of the outer circumferential surface of the back yoke 2 is provided in advance on the inner circumferential surface of the housing 310. By fitting these convex portion 41 and concave portion 311, the iron core 1 of the stator 100 can be positioned with respect to the housing 310. Figure 13A Figure 13B In the case where the rotating electric machine 300 is configured using the iron core 1 illustrated in FIG. 10, as illustrated in FIG. 11, a concave portion 311 corresponding to the convex portion 41 of the outer circumferential surface of the back yoke 2 is provided in advance on the inner circumferential surface of the housing 310. By fitting these convex portion 41 and concave portion 311, the iron core 1 of the stator 100 can be positioned with respect to the housing 310.​

[0168] Figure 14A The illustrated iron core 1 is formed with a recessed portion 42 recessed in the radial direction on the outer peripheral surface of the back yoke 2. The recessed portion 42 is partially provided on the outer peripheral surface of the back yoke 2. In the illustrated example, the recessed portion 42 is provided on the outer peripheral surface of the back yoke 2. However, the recessed portion 42 can be provided on the inner peripheral surface of the back yoke 2. Figure 14A In the illustrated example, a case where the recessed portion 42 is one is shown, but the number of recessed portions 42 can be plural. In the present example, the shape of the recessed portion 42 when the iron core 1 is viewed from above is a rectangular shape. The shape of the recessed portion 42 is not limited to the rectangular shape, and can be, for example, a semicircular shape, a triangular shape, a trapezoidal shape, or the like.

[0169] In a case where the illustrated iron core 1 is used to configure the rotary electric machine 300, as illustrated in FIG. 6, the recessed portion 42 of the back yoke 2 is fitted to the protrusion 312 of the housing 310. By the fitting of the recessed portion 42 and the protrusion 312, the iron core 1 of the stator 100 can be positioned with respect to the housing 310. Figure 14A Figure 14B In a case where the illustrated iron core 1 is used to configure the rotary electric machine 300, as illustrated in FIG. 6, the recessed portion 42 of the back yoke 2 is fitted to the protrusion 312 of the housing 310. By the fitting of the recessed portion 42 and the protrusion 312, the iron core 1 of the stator 100 can be positioned with respect to the housing 310.

[0170] In a case where the illustrated iron core 1 is used to configure the rotary electric machine 300, as illustrated in FIG. 6, the recessed portion 42 of the back yoke 2 is fitted to the protrusion 312 of the housing 310. By the fitting of the recessed portion 42 and the protrusion 312, the iron core 1 of the stator 100 can be positioned with respect to the housing 310. Figure 13A Figure 13B Figure 14A Figure 14B In the illustrated example, a case where the recessed portion 42 is one is shown, but the number of recessed portions 42 can be plural. In the present example, the shape of the recessed portion 42 when the iron core 1 is viewed from above is a rectangular shape. The shape of the recessed portion 42 is not limited to the rectangular shape, and can be, for example, a semicircular shape, a triangular shape, a trapezoidal shape, or the like.

[0171] For example, sometimes a busbar not illustrated is arranged inside the back yoke 2. In this case, a protrusion or a recess is provided on the inner peripheral surface of the back yoke 2 in advance, and a recess or a protrusion corresponding to the protrusion or the recess is provided on the outer peripheral surface of the busbar in advance. By the fitting of the protrusion and the recess, the busbar can be positioned with respect to the iron core 1.

[0172] As described above, at least one of the outer peripheral surface and the inner peripheral surface of the back yoke 2 has the protrusion or the recess, and thus the protrusion or the recess can be used for positioning. In a case where the protrusion or the recess is used for positioning, the shape of the protrusion or the recess when the iron core 1 is viewed from above preferably has at least one straight portion. The straight portion is a portion of the outline of the protrusion or the recess when the iron core 1 is viewed from above, which is constituted by a straight line. The shape of the protrusion or the recess has the straight portion, and thus the positioning accuracy can be improved.

[0173] {Effects of Embodiments}

[0174] The iron core 1, the stator 100, and the rotary electric machine 300 of the above-described embodiments have the following effects. ​​​​

[0175] The core 1 has the first curved portion with a curvature radius of greater than or equal to 0.2 mm at the corner of the tooth 3 and the back yoke 2, whereby the leakage magnetic flux generated at the corner of the tooth 3 and the back yoke 2 can be reduced. Thus, the loss caused by the leakage magnetic flux can be suppressed. In addition, the curvature radius of the first curved portion 31 is less than or equal to 1.5 mm, whereby the reduction in the number of turns of the coil 110 can be suppressed. Thus, the reduction in the torque of the rotary electric machine 300 can be suppressed.

[0176] The stator 100 has the core 1, whereby the magnetic characteristics are excellent. The rotary electric machine 300 has the stator 100, whereby the efficiency is excellent.

[0177] [Experiment Example 1]

[0178] A core having the same structure as the core 1 described in the embodiment was produced, and evaluation thereof was performed. In Experiment Example 1, a plurality of cores having different curvature radii of the first curved portion 31 were prepared. Each core was provided as Sample No. 1-0 to No. 1-6. The stator 100 was produced by winding a wire around each tooth 3 of the prepared core 1 to form a coil 110. Further, the rotary electric machine 300 of the axial gap type was constructed using the produced stator 100. The rotary electric machine 300 functioned as a motor.

[0179] A copper wire having a wire diameter of 1.5 mm was used in the wire winding. The number of turns of the coil of each sample is shown in Table 1.

[0180] The magnetic flux density distribution of the core when a current flows through the coil was analyzed using electromagnetic field analysis software, and the maximum magnetic flux density in the root of the tooth was calculated. The electromagnetic field analysis software used was "JMAG" manufactured by JSOL Co. The maximum magnetic flux density in the tooth root of each sample is shown in Table 1. In addition, the iron loss of the core and the torque of the motor were calculated by electromagnetic field analysis. The results are also shown in Table 1.

[0181] [Table 1]

[0182]

[0183] As is apparent from Table 1, in the samples No. 1-1 to No. 1-6 in which the curvature radius of the first curved portion is greater than or equal to 0.2 mm, the iron loss is smaller than that of the sample No. 1-0 in which the curvature radius is 0 mm. It is considered that in the sample No. 1-0 in which the curvature radius is 0 mm, the magnetic flux takes a shortcut between the peripheral surface of the tooth and the first plane of the back yoke, whereby the iron loss caused by the leakage magnetic flux becomes large. On the contrary, it is considered that in the samples No. 1-1 to No. 1-6, the curvature radius is greater than or equal to 0.2 mm, and thus the leakage magnetic flux that takes a shortcut is reduced, and the iron loss caused by the leakage magnetic flux becomes small.

[0184] From the comparison of the samples No. 1-1 to No. 1-6, it is known that the larger the radius of curvature of the first curved portion, the more the iron loss can be suppressed. However, it is known that in the sample No. 1-6 in which the radius of curvature is 2.0 mm, the torque is reduced compared to the samples No. 1-1 to No. 1-5 in which the radius of curvature is less than or equal to 1.5 mm. The reason for this is that in the sample No. 1-6, the radius of curvature is large, and therefore the number of turns of the coil is reduced compared to the samples No. 1-1 to No. 1-5.

[0185] According to the above, it can also be said that it is preferable that the radius of curvature of the first curved portion be greater than or equal to 0.2 mm and less than or equal to 1.5 mm.

[0186] [Experiment Example 2]

[0187] The stress distribution acting on the punch 50 when the core 1 described in the embodiments is molded by the mold 5 is analyzed by CAE (Computer Aided Engineering). Also, the maximum stress generated at the outer edge corner portion 532 of the step portion 53 in the punch 50 is calculated from the results of the stress analysis by the CAE. In Experiment Example 2, the radius of curvature of the outer edge corner portion 532 is made different, and the maximum stress in each case is calculated. The results thereof are shown in Table 2.

[0188] A configuration analysis software, specifically, "NX Nastran" manufactured by Siemens Corporation, is used in the stress analysis. The analysis conditions are set in the following manner. The molding pressure is set to 980 MPa. The physical property values of the punch 50 are set to Young's modulus: 206000 MPa, and Poisson's ratio: 0.3. In addition, the outer radius R2o of the back yoke 2 of the molded core 1 is set to 25 mm, the inner radius R2i is set to 10 mm, and the thickness T2 is set to 3.0 mm.

[0189] [Table 2]

[0190]

[0191] From Table 2, it is known that the larger the radius of curvature of the outer edge corner portion, the more the maximum stress at the outer edge corner portion at the time of molding of the core can be reduced. In particular, it is known that in the case where the radius of curvature of the outer edge corner portion is greater than or equal to 0.5 mm, the maximum stress generated at the outer edge corner portion can be reduced to less than or equal to 2000 MPa.

[0192] The curved surface of the outer edge corner portion of the step portion in the punch is a portion that molds the outer side curved portion of the back yoke in the core, and therefore it can also be said that it is preferable that the radius of curvature of the outer side curved portion be greater than or equal to 0.5 mm.

[0193] [Experiment Example 3]

[0194] In Test Example 3, the maximum stress generated at the inner edge corner portion 533 of the step portion 53 in the die 50 at the time of core molding was calculated by stress analysis by CAE, similarly to Test Example 2. The result thereof is shown in Table 3. The analysis conditions were the same as in Test Example 2.

[0195] [Table 3]

[0196]

[0197] As is apparent from Table 3, the greater the curvature radius of the inner edge corner portion, the more the maximum stress at the inner edge corner portion at the time of core molding can be reduced. In particular, it is apparent that in the case where the curvature radius of the inner edge corner portion is greater than or equal to 0.5 mm, the maximum stress generated at the inner edge corner portion can be reduced to less than or equal to 2000 MPa, and further reduced to less than or equal to 1500 MPa.

[0198] The curved surface of the inner edge corner portion of the step portion in the die is a portion that molds the inner side curved surface portion of the back yoke in the core, and thus it can also be said that it is preferable that the curvature radius of the inner side curved surface portion be greater than or equal to 0.5 mm. In addition, it is apparent from the results of Table 2 and Table 3 that there is a tendency that the maximum stress at the time of core molding is increased at the outer edge corner portion of the step portion in the die compared to the inner edge corner portion. Thus, it can also be said that it is preferable that the curvature radius of the outer edge corner portion be set to be greater than the curvature radius of the inner edge corner portion, that is, the curvature radius of the outer side curved surface portion be set to be greater than the curvature radius of the inner side curved surface portion. In addition, in view of the fact that the magnetic flux flowing in the back yoke selectively easily passes at the inner peripheral side, it can also be said that it is preferable that the curvature radius of the outer side curved surface portion be set to be greater than the curvature radius of the inner side curved surface portion from the viewpoint of motor performance.

[0199] The following supplementary notes are further disclosed in relation to the above-described embodiments of the application.

[0200] [Supplementary Note 1]

[0201] A core that is used in a rotary electric machine of an axial gap type,

[0202] The core has:

[0203] a ring-shaped back yoke; and

[0204] a plurality of teeth that project in an axial direction from a first plane of the back yoke,

[0205] the plurality of teeth are provided at intervals in a circumferential direction of the first plane,

[0206] the back yoke and the teeth are composed of a powder compact that is integrally molded,

[0207] the first curved surface portion connecting between the peripheral surface of the tooth and the first plane of the back yoke,

[0208] The radius of curvature of the first curved surface portion is greater than or equal to 0.2 mm and less than or equal to 1.5 mm.

[0209] The iron core according to the supplementary note 1 is capable of reducing leakage magnetic flux generated at the corner of the tooth and the back yoke by having the first curved surface portion at the corner of the tooth and the back yoke. Thus, the iron core according to the supplementary note 1 is capable of improving magnetic characteristics. The radius of curvature of the first curved surface portion is greater than or equal to 0.2 mm, and thus leakage magnetic flux can be effectively reduced. In addition, the radius of curvature of the first curved surface portion is less than or equal to 1.5 mm, and thus the space for the coil arranged in the tooth can be ensured, and the increase in the coil space factor can be achieved. Thus, the reduction in the number of turns of the coil can be suppressed, and thus the reduction in the torque of the rotary electric machine can be suppressed.

[0210] [Supplementary Note 2]

[0211] The iron core according to the supplementary note 1 has:

[0212] an outer curved surface portion connecting between the first plane and the outer peripheral surface of the back yoke; and

[0213] an inner curved surface portion connecting between the first plane and the inner peripheral surface of the back yoke,

[0214] The radius of curvature of each of the outer curved surface portion and the inner curved surface portion is greater than or equal to 0.5 mm and less than or equal to 5.0 mm.

[0215] The above-described iron core composed of a powder compact is formed by compression of a soft magnetic powder using a mold. When the iron core is formed using a mold, stress is easily concentrated at the corner of the mold, particularly, a punch, and cracking can occur at the corner of the mold. The mode according to the supplementary note 2 is such that the radius of curvature of each of the outer curved surface portion and the inner curved surface portion of the back yoke is greater than or equal to 0.5 mm, and thus stress concentration at the corner of the mold can be alleviated. Thus, the above-described mode is capable of suppressing damage to the mold. If the radius of curvature of each of the outer curved surface portion and the inner curved surface portion is increased, the length of the linear portion of the outer peripheral surface and the inner peripheral surface of the back yoke with respect to the thickness of the back yoke is decreased. If the radius of curvature of each of the outer curved surface portion and the inner curved surface portion is less than or equal to 5.0 mm, the length of the linear portion of the outer peripheral surface and the inner peripheral surface of the back yoke can be easily ensured to be large.

[0216] [Supplementary Note 3]

[0217] In the iron core according to the supplementary note 1, the powder compact is composed of an aggregate of a plurality of coated soft magnetic particles having an insulating coating on the surface of a soft magnetic particle,

[0218] The average particle diameter of the soft magnetic particles is greater than or equal to 20 μm and less than or equal to 300 μm.

[0219] The average particle diameter of the soft magnetic particles constituting the powder compact is dependent on the average particle diameter of the soft magnetic powder included in the raw material powder. The average particle diameter of the soft magnetic particles is greater than or equal to 20 μm and less than or equal to 300 μm, whereby a high-density powder compact is easily obtained with high density.

[0220] The average particle diameter of the soft magnetic particles in the powder compact can be found by the following method.

[0221] An arbitrary cross section of the powder compact is observed by a microscope such as a scanning electron microscope (SEM) or an optical microscope. All the soft magnetic particles present in the observation field are extracted, and the area of each particle is measured. The diameter of a circle having an area equal to that of each particle is calculated, and the average value thereof is set as the average particle diameter of the soft magnetic particles. The size of the observation field is set to include, for example, greater than or equal to 50 soft magnetic particles. The extraction of the soft magnetic particles, the measurement of the area, and the calculation of the equivalent diameter of the circle can be performed using image analysis software or the like.

[0222] [Note 4]

[0223] In the core described in Note 1, the powder compact is composed of a collection of a plurality of coated soft magnetic particles having an insulating coating on the surface of the soft magnetic particles,

[0224] The average particle diameter of the soft magnetic particles is greater than or equal to 40 μm and less than or equal to 250 μm.

[0225] The average particle diameter of the soft magnetic particles is greater than or equal to 40 μm and less than or equal to 250 μm, whereby a more dense and high-density powder compact is easily obtained.

[0226] [Note 5]

[0227] In the core described in Note 1, the relative density of the powder compact is greater than or equal to 93%.

[0228] The relative density of the powder compact is greater than or equal to 93%, whereby the density of the powder compact is high. By densification of the powder compact, the mechanical strength and the magnetic characteristics of the core can be improved.

[0229] Explanation of Reference Numerals

[0230] 1 Core

[0231] 2 Rear yoke

[0232] 21 First plane 22 Second plane

[0233] 23 outer curved portion 24 inner curved portion

[0234] 25, 26 straight portion

[0235] 27 outer peripheral region 28 inner peripheral region

[0236] 3 tooth

[0237] 31 first curved portion

[0238] 41 convex portion 42 concave portion

[0239] 5 mold

[0240] 50 punch

[0241] 51 first molding portion 52 second molding portion

[0242] 53 step portion

[0243] 531 first corner portion

[0244] 532 outer edge corner portion 533 inner edge corner portion

[0245] 60 mandrel

[0246] 70 upper punch 80 lower punch 82 punch portion

[0247] 100 stator

[0248] 110 coil 200 rotor

[0249] 210 holding plate 220 magnet

[0250] 300 rotary electric machine

[0251] 310 housing

[0252] 311 concave portion 312 convex portion

[0253] 320 plate

[0254] 330 rotation shaft 340 bearing

[0255] T2 thickness

[0256] R20, R30 outer radius

[0257] R31, R21 inner radius

[0258] H3 height position

Claims

1. An iron core used in a rotating electrical machine of an axial gap type, the iron core having: a back yoke; and a tooth projecting in an axial direction perpendicular to a first plane of the back yoke, the back yoke having a second plane as a face on an opposite side to the first plane, the back yoke and the tooth being composed of a powder-molded body integrally molded, a first curved surface portion connecting between a peripheral surface of the tooth and the first plane of the back yoke is provided at a corner of the tooth and the back yoke, a distance of the first curved surface portion from the second plane is larger toward a peripheral surface of the tooth from the first plane, a radius of curvature of the first curved surface portion is larger than or equal to 0.2 mm and smaller than or equal to 1.5 mm, the iron core having: an outer curved surface portion connecting between the first plane and an outer peripheral surface of the back yoke; and an inner curved surface portion connecting between the first plane and an inner peripheral surface of the back yoke, each radius of curvature of the outer curved surface portion and the inner curved surface portion is larger than or equal to 0.5 mm and smaller than or equal to 85% of a thickness of the back yoke, the iron core being integrally molded by a stepped die.

2. The iron core according to claim 1, wherein the back yoke is annular and has a plurality of teeth projecting in an axial direction perpendicular to the first plane, the plurality of teeth are provided at intervals in a circumferential direction of the first plane.

3. The iron core according to claim 1, wherein the radius of curvature of the outer curved surface portion and the radius of curvature of the inner curved surface portion are different.

4. The iron core according to any one of claims 1 to 3, wherein at least one of the outer peripheral surface and the inner peripheral surface of the back yoke has a straight portion extending in an axial direction, a length of the straight portion is larger than or equal to 15% of a thickness of the back yoke.

5. The iron core according to any one of claims 1 to 3, wherein a difference between a radial dimension from a center of an axis of the back yoke to the outer peripheral surface and a radial dimension from the center of the axis of the back yoke to a face of the tooth on an outer peripheral side is smaller than or equal to 6.0 mm.

6. The iron core according to any one of claims 1 to 3, wherein a difference between a radial dimension from a center of an axis of the back yoke to a face of the tooth on an inner peripheral side and a radial dimension from the center of the axis of the back yoke to the inner peripheral surface is smaller than or equal to 7.0 mm.

7. The iron core according to any one of claims 1 to 3, wherein a convex portion projecting in a radial direction or a concave portion recessed in a radial direction is provided locally at least one of the outer peripheral surface and the inner peripheral surface of the back yoke.

8. The iron core according to any one of claims 1 to 3, wherein the powder-molded body is composed of an aggregate of a plurality of coated soft magnetic particles having an insulating coating on surfaces of soft magnetic particles, the soft magnetic particles are iron-based particles composed of pure iron or at least one iron-based alloy selected from a Fe-Si-based alloy, a Fe-Al-based alloy, a Fe-Cr-Al-based alloy, and a Fe-Cr-Si-based alloy.

9. The iron core according to claim 8, wherein the insulating coating includes a phosphate coating.

10. The iron core according to any one of claims 1 to 3, wherein The green compact has a relative density of 90% or more.

11. An iron core used in a rotating electrical machine of an axial gap type, The iron core has: a back yoke; and teeth protruding in an axial direction perpendicular to a first plane of the back yoke, the back yoke has a second plane as a face on an opposite side to the first plane, the back yoke and the teeth are composed of a green compact integrally molded, a first curved surface portion connecting between a peripheral surface of the teeth and the first plane of the back yoke is provided at a corner of the teeth and the back yoke, a distance of the first curved surface portion from the second plane increases from the first plane toward the peripheral surface of the teeth, a radius of curvature of the first curved surface portion is 0.2 mm or more and 1.5 mm or less, The iron core has: an outer curved surface portion connecting between the first plane and an outer peripheral surface of the back yoke; and an inner curved surface portion connecting between the first plane and an inner peripheral surface of the back yoke, each radius of curvature of the outer curved surface portion and the inner curved surface portion is 0.5 mm or more and 85% or less of a thickness of the back yoke, at least one of the outer peripheral surface and the inner peripheral surface of the back yoke has a straight portion extending in the axial direction, a length of the straight portion is 15% or more of the thickness of the back yoke, the iron core is integrally molded by a stepped die.

12. The iron core according to claim 11, wherein the back yoke is annular and has a plurality of teeth protruding in an axial direction perpendicular to the first plane, the plurality of teeth are disposed at intervals in a circumferential direction of the first plane.

13. A stator that is a stator of a rotating electrical machine of an axial gap type, The stator has: the iron core according to any one of claims 1 to 12; and a coil disposed on each tooth of the iron core.

14. A rotating electrical machine having a rotor and a stator, which is a rotating electrical machine of an axial gap type in which the rotor and the stator are disposed in opposition in an axial direction, In the rotating electrical machine, the stator is the stator according to claim 13.

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