Core piece, stator core, stator, and axial gap motor

Abstract

This core piece, which is for a stator core of an axial gap motor and which is obtained by pressing a soft magnetic powder that is covered with an insulating material, comprises a tooth part, a first flange part, and a second flange part. The tooth part has a tooth part inside surface, a tooth part outside surface, a tooth part first side surface, and a tooth part second side surface. The tooth part first side surface has a tooth part inner first side surface that is connected to the tooth part inside surface, a tooth part outer first side surface that is connected to the tooth part outside surface, and a tooth part intermediate first side surface that is smoothly connected to the tooth part inner first side surface and the tooth part outer first side surface. The tooth part second side surface has a tooth part inner second side surface that is connected to the tooth part inside surface and that is parallel to the tooth part inner first side surface, a tooth part outer second side surface that is connected to the tooth part outside surface and that is parallel to the tooth part outer first side surface, and a tooth part intermediate second side surface that is smoothly connected to the tooth part inner second side surface and the tooth part outer second side surface.

Description

Core piece, stator core, stator, and axial gap motor

[0001] The present invention relates to a core piece of a stator core of an axial gap motor, a stator core of an axial gap motor, a stator of an axial gap motor, and an axial gap motor.

[0002] Patent Document 1 describes a core piece for constructing a stator core of an axial gap motor. The core piece is a powder-pressed compact, and includes a columnar first member (teeth portion) extending in the axial direction of the stator core, a plate-shaped second member (first flange portion) provided at a first axial end of the first member, and a plate-shaped third member (second flange portion) provided at a second axial end of the first member. Each of the first, second, and third members has an outer circumferential surface disposed on the outer circumferential side of the stator core, an inner circumferential surface disposed on the inner circumferential side of the stator core, and a first side surface and a second side surface connected to the outer circumferential surface and the inner circumferential surface. Furthermore, to enable the first, second, and third members to be integrally powder-pressed, the first side surface and the second side surface of each of the first, second, and third members are formed by a first straight portion, a second straight portion, and a tapered portion. The first straight portion and the second straight portion are surfaces that are parallel to each other, and the tapered portion is a surface that becomes thinner from the outer peripheral surface side toward the inner peripheral surface side.

[0003] Patent No. 6987327

[0004] We fabricated core pieces in which the first and second side surfaces of the teeth were formed by a first straight portion, a second straight portion, and a tapered portion, similar to the core pieces described in Patent Document 1, and evaluated the motor characteristics. As a result, we were unable to obtain the expected characteristics.

[0005] Therefore, an object of the present disclosure is to provide a core piece, a stator core, a stator, and an axial gap motor that can improve the characteristics of the motor.

[0006] In light of the above-mentioned problems, further intensive research led to the following findings: When the tapered portion is bent and connected to at least one of the first straight portion and the second straight portion, the connection position between the tapered portion and at least one of the first straight portion and the second straight portion forms a corner (corner point). Around the corner, powder does not flow smoothly. Therefore, when the core pieces are compacted, smooth flow of powder is hindered around the connection position between the tapered portion and the second straight portion. As a result, the density of the core pieces, which are compacted powder bodies, varies greatly, and it is believed that the motor characteristics are not fully exhibited. The present disclosure is based on the above-mentioned findings.

[0007] [1] A core piece according to the present disclosure is a core piece for a stator core of an axial gap motor, formed by pressing soft magnetic powder coated with an insulating material, and includes: teeth portions having peripheral surfaces extending in a first direction and around which windings are wound; first flange portions arranged on one side of the teeth portions in the first direction; and second flange portions arranged on the opposite side of the teeth portions from the first flange portions in the first direction. The teeth portions have teeth inner side surfaces and teeth outer side surfaces that face each other in a second direction perpendicular to the first direction, and teeth first side surfaces and teeth second side surfaces connected to the teeth inner side surfaces and teeth outer side surfaces. The first side surface of the teeth has an inner first side surface connected to the inner side surface of the teeth, an outer first side surface connected to the outer side surface of the teeth, and a middle first side surface smoothly connected to the inner first side surface and the outer first side surface of the teeth, and the second side surface of the teeth has an inner second side surface connected to the inner side surface of the teeth and parallel to the inner first side surface of the teeth, an outer second side surface connected to the outer side surface of the teeth and parallel to the outer first side surface of the teeth, and a middle second side surface smoothly connected to the inner second side surface and the outer second side surface of the teeth.

[0008] In this core piece, the first inner side surface and the second inner side surface connected to the inner tooth surface are parallel to each other, and the first outer side surface and the second outer side surface connected to the outer tooth surface are parallel to each other. This facilitates powder compaction. The first intermediate side surface is smoothly connected to the first inner side surface and the first outer side surface, and the second intermediate side surface is smoothly connected to the second inner side surface and the second outer side surface. In other words, there are no corners at the connection positions between the first intermediate side surface and the first inner side surface and between the second intermediate side surface and the second inner side surface and the second outer side surface. This allows powder to flow smoothly around the connection positions between the first intermediate side surface and the first inner side surface and the first outer side surface, and around the connection positions between the second intermediate side surface and the second inner side surface and the second outer side surface. This makes it possible to suppress variations in density of the core pieces, thereby improving the characteristics of the motor.

[0009] [2] In the core piece described in [1], the first side surface of the teeth and the second side surface of the teeth may be angular in a cross section perpendicular to the first direction. In this core piece, the first side surface of the teeth and the second side surface of the teeth do not have angular sections in a cross section perpendicular to the first direction. Because the first side surface of the teeth and the second side surface of the teeth do not have angular sections in a cross section perpendicular to the first direction, powder can flow smoothly along the first side surface of the teeth and the second side surface of the teeth when the core piece is compacted. This can further reduce variations in density of the core piece, thereby further improving motor characteristics.

[0010] [3] In the core piece according to [1] or [2], the maximum curvature of the first side surface of the teeth and the second side surface of the teeth in a cross section perpendicular to the first direction may be 0.1 or less. In this core piece, the maximum curvature of the first side surface of the teeth and the second side surface of the teeth in a cross section perpendicular to the first direction is 0.1 or less, so that when the core piece is powder-compacted, the powder can flow smoothly along the first side surface of the teeth and the second side surface of the teeth. This can further reduce variations in density of the core piece, thereby further improving motor characteristics.

[0011] [4] In the core piece according to any one of [1] to [3], the first flange portion has a first flange portion inner end face and a first flange portion outer end face that face each other in the second direction, and a first flange portion first end face and a first flange portion second end face that are connected to the first flange portion inner end face and the first flange portion outer end face, and the first flange portion first end face has a first flange portion inner first end face that is connected to the first flange portion inner end face, a first flange portion outer first end face that is connected to the first flange portion outer end face, and The first flange second end face may have a first flange inner second end face connected to the first flange inner end face and parallel to the first flange inner first end face, a first flange outer second end face connected to the first flange outer end face and parallel to the first flange outer first end face, and a first flange intermediate second end face smoothly connected to the first flange inner second end face and the first flange outer second end face.

[0012] In this core piece, the first flange-inner first end face and the first flange-inner second end face connected to the first flange-inner end face are parallel to each other, and the first flange-outer first end face and the first flange-outer second end face connected to the first flange-outer end face are parallel to each other. This facilitates powder compaction. The first flange-intermediate first end face is smoothly connected to the first flange-inner first end face and the first flange-outer first end face, and the first flange-intermediate second end face is smoothly connected to the first flange-inner second end face and the first flange-outer second end face. In other words, no corners are formed at the connection positions between the first flange-intermediate first end face and the first flange-inner first end face and the first flange-outer first end face, and no corners are formed at the connection positions between the first flange-intermediate second end face and the first flange-inner second end face and the first flange-outer second end face. Therefore, when the core pieces are compacted, the powder can flow smoothly around the connection positions between the first flange intermediate first end face and the first flange inner first end face and the first flange outer first end face, and around the connection positions between the first flange intermediate second end face and the first flange inner second end face and the first flange outer second end face, thereby suppressing variations in density of the core pieces and improving motor characteristics.

[0013] [5] In the core piece according to [4], the first flange first end face and the first flange second end face may be cornerless in a cross section perpendicular to the first direction. In this core piece, the first flange first end face and the first flange second end face have no corners in a cross section perpendicular to the first direction. Therefore, when the core piece is compacted, the powder can flow smoothly along the first flange first end face and the first flange second end face. This further reduces density variations in the core pieces, thereby further improving motor performance.

[0014] [6] In the core piece according to [4] or [5], the maximum curvature of the first flange first end face and the first flange second end face in a cross section perpendicular to the first direction may be 0.1 or less. In this core piece, the maximum curvature of the first flange first end face and the first flange second end face in a cross section perpendicular to the first direction is 0.1 or less. Therefore, when the core piece is powder-compacted, the powder can flow smoothly along the first flange first end face and the first flange second end face. This can further reduce variations in density of the core piece, thereby further improving motor characteristics.

[0015] [7] In the core piece according to any one of [1] to [6], the second flange has a second flange inner end face and a second flange outer end face that face each other in the second direction, and a second flange first end face and a second flange second end face that are connected to the second flange inner end face and the second flange outer end face, and the second flange first end face has a second flange inner first end face that is connected to the second flange inner end face, a second flange outer first end face that is connected to the second flange outer end face, and The second flange second end face may have a second flange inner second end face connected to the second flange inner end face and parallel to the second flange inner first end face, a second flange outer second end face connected to the second flange outer end face and parallel to the second flange outer first end face, and a second flange intermediate second end face smoothly connected to the second flange inner second end face and the second flange outer second end face.

[0016] In this core piece, the second flange inner first end face and the second flange inner second end face connected to the second flange inner end face are parallel to each other, and the second flange outer first end face and the second flange outer second end face connected to the second flange outer end face are parallel to each other. This facilitates powder compaction. The second flange intermediate first end face is smoothly connected to the second flange inner first end face and the second flange outer first end face, and the second flange intermediate second end face is smoothly connected to the second flange inner second end face and the second flange outer second end face. In other words, no corners are formed at the connection positions between the second flange intermediate first end face and the second flange inner first end face and the second flange outer first end face, and no corners are formed at the connection positions between the second flange intermediate second end face and the second flange inner second end face and the second flange outer second end face. Therefore, when the core pieces are compacted, the powder can flow smoothly around the connection positions between the second flange intermediate first end face and the second flange inner first end face and the second flange outer first end face, and around the connection positions between the second flange intermediate second end face and the second flange inner second end face and the second flange outer second end face, thereby suppressing variations in the density of the core pieces and improving the motor characteristics.

[0017] [8] In the core piece according to [7], the first end face of the second flange and the second end face of the second flange may be cornerless in a cross section perpendicular to the first direction. In this core piece, the first end face of the second flange and the second end face of the second flange are cornerless in a cross section perpendicular to the first direction. Therefore, when the core piece is compacted, the powder can flow smoothly along the first end face of the second flange and the second end face of the second flange. This further reduces variations in density of the core piece, thereby further improving the motor characteristics.

[0018] [9] In the core piece according to [7] or [8], the maximum curvature of the second flange first end face and the second flange second end face in a cross section perpendicular to the first direction may be 0.1 or less. In this core piece, the maximum curvature of the second flange first end face and the second flange second end face in a cross section perpendicular to the first direction is 0.1 or less. Therefore, when the core piece is powder-compacted, the powder can flow smoothly along the second flange first end face and the second flange second end face. This can further suppress variations in density of the core piece, thereby further improving motor characteristics.

[0019]

[10] In the core piece according to any one of [1] to [9], the first flange portion and the second flange portion may have the same shape. In this core piece, since the first flange portion and the second flange portion have the same shape, the mold for powder compacting the core piece can have a simpler shape. This can further reduce the manufacturing cost of the core piece.

[0020]

[11] A stator core according to the present disclosure is a stator core for an axial gap motor, and includes the core pieces according to any one of [1] to

[10] . Because this stator core includes the core pieces described above, the characteristics of the motor can be improved.

[0021]

[12] A stator according to the present disclosure is a stator for an axial gap motor, and includes the stator core according to

[11] and a winding wound around the core pieces of the stator core. Because this stator includes the stator core described above, the characteristics of the motor can be improved.

[0022]

[13] An axial gap motor according to the present disclosure includes the stator described in

[12] and a rotor rotatably disposed relative to the stator. Because this axial gap motor includes the above-described stator, the motor characteristics can be improved.

[0023] The motor characteristics can be improved.

[0024] FIG. 1 is a schematic cross-sectional view showing an axial gap motor according to an embodiment. FIG. 2 is a schematic diagram showing a stator core according to an embodiment. FIG. 3 is a perspective view showing a core piece according to an embodiment. FIG. 4 is a perspective view showing a core piece according to an embodiment. FIG. 5 is a side view showing a core piece according to an embodiment. FIG. 6 is a cross-sectional view taken along line VI-VI shown in FIG. 5. FIG. 7 is a cross-sectional view taken along line VII-VII shown in FIG. 5. FIG. 8 is a cross-sectional view taken along line VIII-VIII shown in FIG. 5. FIG. 9 is a cross-sectional view showing a core piece manufacturing device. FIG. 10 is a cross-sectional view showing a core piece manufacturing device. FIG. 11 is a cross-sectional view showing a core piece manufacturing device.

[0025] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. In the drawings, identical or corresponding parts are designated by the same reference numerals, and duplicate explanations will be omitted. Also, in the drawings, dimensional proportions and the like have been appropriately changed to make the explanation easier to understand.

[0026] [Axial Gap Motor] Fig. 1 is a schematic cross-sectional view showing an axial gap motor according to an embodiment. As shown in Fig. 1, the axial gap motor 1 according to this embodiment includes a stator 2, a rotor 3 arranged rotatably relative to the stator 2, and a shaft 4 fixed to the rotor 3. The stator 2 and the rotor 3 are arranged to be spaced apart in the axial direction of the shaft 4.

[0027] [Stator, Stator Core] Fig. 2 is a schematic diagram showing a stator according to an embodiment. As shown in Figs. 1 and 2, the stator 2 according to this embodiment is a stator for an axial gap motor 1. The stator 2 includes a stator core 5 having a plurality of core pieces 7, and windings 6 wound around each of the plurality of core pieces 7. In the drawings, as an example, the stator core 5 is shown as having 12 core pieces 7. The stator core 5 is the portion of the stator 2 excluding the windings 6. A shaft hole 8 through which the shaft 4 is inserted is formed in the center of the stator core 5.

[0028] [Core Lamination] Fig. 3 is a perspective view showing a core lamination according to the embodiment. Fig. 4 is a perspective view showing a core lamination according to the embodiment. Fig. 5 is a side view showing a core lamination according to the embodiment. Fig. 6 is a cross-sectional view taken along line VI-VI in Fig. 5. Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 5. Fig. 8 is a cross-sectional view taken along line VIII-VIII in Fig. 5. As shown in Figs. 3 to 8, the core lamination 7 according to this embodiment is a core lamination of the stator core 5 of the axial gap motor 1. In other words, the core lamination 7 constitutes a part of the stator core 5 of the axial gap motor 1.

[0029] The core pieces 7 are compacts formed by pressing soft magnetic powder coated with an insulating material. Examples of the soft magnetic powder material include pure iron, iron-silicon, and iron-cobalt. The average particle size of the soft magnetic powder is, for example, 3 μm to 300 μm, 30 μm to 200 μm, or 50 μm to 150 μm. Examples of the insulating material include an insulating coating containing phosphoric acid, silicone, or the like. The average particle size of the soft magnetic powder is measured using a robot shifter (model number: RPS-205) manufactured by Seishin Enterprise Co., Ltd.

[0030] Each core piece 7 includes a tooth portion 10 extending in a first direction D1, a first flange portion 20 arranged on one side of the tooth portion 10 in the first direction D1, and a second flange portion 30 arranged on the opposite side of the tooth portion 10 in the first direction D1 from the first flange portion 20. Here, the direction perpendicular to the first direction D1 is referred to as a second direction D2, and the direction perpendicular to the first direction D1 and the second direction D2 is referred to as a third direction D3.

[0031] The teeth 10 have peripheral surfaces 11 around which the windings 6 (see FIG. 1 ) are wound. The peripheral surfaces 11 of the teeth 10 have teeth inner surfaces 13 and teeth outer surfaces 14 facing the second direction D2, and teeth first side surfaces 15 and teeth second side surfaces 16 connected to the teeth inner surfaces 13 and teeth outer surfaces 14 and facing the third direction D3. The teeth inner surfaces 13 are surfaces facing the shaft holes 8 in the stator core 5 (the radially inner side of the stator core 5). The teeth outer surfaces 14 are surfaces facing the opposite side of the shaft holes 8 in the stator core 5 (the radially outer side of the stator core 5).

[0032] The tooth inner surface 13 and the tooth outer surface 14 are formed in a planar or curved shape. When the tooth inner surface 13 and the tooth outer surface 14 are formed in a planar shape, the tooth inner surface 13 and the tooth outer surface 14 are, for example, arranged parallel to each other and extending linearly in the third direction D3. That is, the tooth inner surface 13 and the tooth outer surface 14 are formed in a planar shape extending along the first direction D1 and the third direction D3. When the tooth inner surface 13 and the tooth outer surface 14 are formed in a curved shape, for example, convex outward. In this embodiment, the tooth inner surface 13 and the tooth outer surface 14 are described as being formed in a planar shape extending along the first direction D1 and the third direction D3. The tooth inner surface 13 is formed shorter in the third direction D3 than the tooth outer surface 14. In other words, the length of the tooth inner surface 13 in the third direction D3 is shorter than the length of the tooth outer surface 14 in the third direction D3.

[0033] The tooth first side surface 15 has a tooth inner first side surface 15a connected to the tooth inner side surface 13, a tooth outer first side surface 15b connected to the tooth outer side surface 14, and a tooth intermediate first side surface 15c connected to the tooth inner first side surface 15a and the tooth outer first side surface 15b.

[0034] The tooth portion second side surface 16 has a tooth portion inner second side surface 16a connected to the tooth portion inner side surface 13, a tooth portion outer second side surface 16b connected to the tooth portion outer side surface 14, and a tooth portion intermediate second side surface 16c connected to the tooth portion inner second side surface 16a and the tooth portion outer second side surface 16b.

[0035] The tooth inner first side surface 15a and the tooth inner second side surface 16a are arranged parallel to each other. The tooth inner first side surface 15a is formed in a planar shape and extends linearly in the second direction D2 from one edge of the tooth inner surface 13 in the third direction D3. The tooth inner second side surface 16a is formed in a planar shape and extends linearly in the second direction D2 from the edge of the tooth inner surface 13 opposite to the tooth inner first side surface 15a in the third direction D3.

[0036] The tooth outer first side surface 15b and the tooth outer second side surface 16b are arranged parallel to each other. The tooth outer first side surface 15b is formed in a planar shape and extends linearly in the second direction D2 from one edge of the tooth outer surface 14 in the third direction D3. The tooth outer second side surface 16b is formed in a planar shape and extends linearly in the second direction D2 from the edge of the tooth outer surface 14 opposite to the tooth outer first side surface 15b in the third direction D3.

[0037] The distance between the teeth intermediate first side surface 15c and the teeth intermediate second side surface 16c in the third direction D3 becomes narrower from the teeth outer side surface 14 toward the teeth inner side surface 13. In other words, the teeth 10 become thinner at the teeth intermediate first side surface 15c and the teeth intermediate second side surface 16c from the teeth outer side surface 14 toward the teeth inner side surface 13.

[0038] The teeth intermediate first side surface 15c is smoothly connected to the teeth inner first side surface 15a and the teeth outer first side surface 15b. The smooth connection of the teeth intermediate first side surface 15c with the teeth inner first side surface 15a and the teeth outer first side surface 15b means that there are no corners (corners) at the connection positions of the teeth intermediate first side surface 15c with the teeth inner first side surface 15a and the teeth outer first side surface 15b, and that the teeth intermediate first side surface 15c with the teeth inner first side surface 15a and the teeth outer first side surface 15b are connected in a streamlined manner. The teeth intermediate first side surface 15c curves from the teeth inner first side surface 15a and extends in a streamlined manner toward the teeth outer side surface 14 so that no corners (corners) are formed between the teeth intermediate first side surface 15c and the teeth inner first side surface 15a. Teeth-part intermediate first side surface 15c curves from teeth-part outer first side surface 15b and extends in a streamlined manner toward teeth-part inner side surface 13 so as not to form any corners (corner points) with teeth-part outer first side surface 15b. In a cross section perpendicular to first direction D1 (cross section shown in FIG. 7), teeth-part intermediate first side surface 15c may or may not have a linearly extending portion.

[0039] Furthermore, the teeth intermediate second side surface 16c is smoothly connected to the teeth inner second side surface 16a and the teeth outer second side surface 16b. The smooth connection of the teeth intermediate second side surface 16c with the teeth inner second side surface 16a and the teeth outer second side surface 16b means that there are no corners (corners) at the connection positions of the teeth intermediate second side surface 16c with the teeth inner second side surface 16a and the teeth outer second side surface 16b, and that the teeth intermediate second side surface 16c with the teeth inner second side surface 16a and the teeth outer second side surface 16b are connected in a streamlined manner. The teeth intermediate second side surface 16c curves from the teeth inner second side surface 16a and extends in a streamlined manner toward the teeth outer side surface 14 so that no corners (corners) are formed between the teeth intermediate second side surface 16c and the teeth inner second side surface 16a. The teeth intermediate second side surface 16c curves from the teeth outer second side surface 16b and extends in a streamlined manner toward the teeth inner side surface 13 so as not to form any corners (corner points) between the teeth intermediate second side surface 16c and the teeth outer second side surface 16b. In a cross section perpendicular to the first direction D1 (the cross section shown in FIG. 7), the teeth intermediate second side surface 16c may or may not have a linearly extending portion.

[0040] Each of the first side surface 15 and the second side surface 16 of the teeth has no corners (corner points) in a cross section perpendicular to the first direction D1 (the cross section shown in FIG. 7 ). The maximum curvature of each of the first side surface 15 and the second side surface 16 of the teeth in a cross section perpendicular to the first direction D1 is, for example, 0.1 or less, preferably 0.06 or less, and more preferably 0.04 or less.

[0041] In addition, when the inner surface 13 of the tooth portion and the outer surface 14 of the tooth portion are curved, the inner surface 13 of the tooth portion can be, for example, a curved surface concentric with the inner surface of the stator 2, and the outer surface 14 of the tooth portion can be a curved surface concentric with the outer surface of the stator 2.

[0042] The first flange 20 is formed in a plate shape and protrudes from the tooth 10 in a direction perpendicular to the first direction D1. The first flange 20 protrudes from the tooth 10 when viewed from the first direction D1. The first flange 20 also protrudes from one end of the tooth 10 in the first direction D1 in directions along the second direction D2 and the third direction D3.

[0043] The first flange portion 20 has a first flange portion outer surface 21 and a first flange portion inner surface 22 that face in the first direction D1. The first flange portion outer surface 21 is a surface that faces the opposite side from the second flange portion 30 in the first direction D1. The first flange portion inner surface 22 is a surface that faces the second flange portion 30 side in the first direction D1 and to which the teeth portion 10 is connected. The first flange portion outer surface 21 and the first flange portion inner surface 22 are arranged parallel to each other and formed into planar shapes that extend in the second direction D2 and the third direction D3.

[0044] The first flange 20 is composed of a first flange inner end face 23 and a first flange outer end face 24 that face the second direction D2, and a first flange first end face 25 and a first flange second end face 26 that are connected to the first flange inner end face 23 and the first flange outer end face 24 and face the third direction D3. The first flange inner end face 23 is a surface that faces the shaft hole 8 side of the stator core 5 (the radially inner side of the stator core 5). The first flange outer end face 24 is a surface that faces the opposite side of the stator core 5 from the shaft hole 8 (the radially outer side of the stator core 5).

[0045] The first flange inner end surface 23 and the first flange outer end surface 24 are formed in a flat or curved shape. When the first flange inner end surface 23 and the first flange outer end surface 24 are formed in a flat shape, the first flange inner end surface 23 and the first flange outer end surface 24 are, for example, arranged parallel to each other and extending linearly in the third direction D3. In other words, the first flange inner end surface 23 and the first flange outer end surface 24 are formed in a flat shape extending along the first direction D1 and the third direction D3. When the first flange inner end surface 23 and the first flange outer end surface 24 are formed in a curved shape, for example, convex outward. In the present embodiment, the first flange inner end face 23 and the first flange outer end face 24 are described as being formed in a planar shape extending along the first direction D1 and the third direction D3. Therefore, in the present embodiment, the first flange inner end face 23 and the first flange outer end face 24 are arranged parallel to the teeth inner side surface 13 and the teeth outer side surface 14 of the teeth portion 10. The first flange inner end face 23 is formed shorter in the third direction D3 than the first flange outer end face 24. In other words, the length of the first flange inner end face 23 in the third direction D3 is shorter than the length of the first flange outer end face 24 in the third direction D3.

[0046] The first flange first end face 25 has a first flange inner first end face 25a connected to the first flange inner end face 23, a first flange outer first end face 25b connected to the first flange outer end face 24, and a first flange intermediate first end face 25c connected to the first flange inner first end face 25a and the first flange outer first end face 25b.

[0047] The first flange second end face 26 has a first flange inner second end face 26a connected to the first flange inner end face 23, a first flange outer second end face 26b connected to the first flange outer end face 24, and a first flange intermediate second end face 26c connected to the first flange inner second end face 26a and the first flange outer second end face 26b.

[0048] The first flange inner first end face 25a and the first flange inner second end face 26a are arranged parallel to each other. The first flange inner first end face 25a is formed in a planar shape and extends linearly in the second direction D2 from one edge of the first flange inner end face 23 in the third direction D3. The first flange inner second end face 26a is formed in a planar shape and extends linearly in the second direction D2 from the edge of the first flange inner end face 23 opposite the first flange inner first end face 25a in the third direction D3.

[0049] The first flange outer first end face 25b and the first flange outer second end face 26b are arranged parallel to each other. The first flange outer first end face 25b is formed in a planar shape and extends linearly in the second direction D2 from one edge of the first flange outer end face 24 in the third direction D3. The first flange outer second end face 26b is formed in a planar shape and extends linearly in the second direction D2 from the edge of the first flange outer end face 24 opposite the first flange outer first end face 25b in the third direction D3.

[0050] The distance between the first flange intermediate first end face 25c and the first flange intermediate second end face 26c in the third direction D3 becomes narrower from the first flange outer end face 24 side toward the first flange inner end face 23 side. In other words, the first flange 20 becomes narrower at the first flange intermediate first end face 25c and the first flange intermediate second end face 26c from the first flange outer end face 24 side toward the first flange inner end face 23 side.

[0051] The first flange intermediate first end face 25c is smoothly connected to the first flange inner first end face 25a and the first flange outer first end face 25b. The phrase "the first flange intermediate first end face 25c is smoothly connected to the first flange inner first end face 25a and the first flange outer first end face 25b" means that there are no corners (corner points) at the connection positions of the first flange intermediate first end face 25c and the first flange inner first end face 25a and the first flange outer first end face 25b, and that the first flange intermediate first end face 25c is connected to the first flange inner first end face 25a and the first flange outer first end face 25b in a streamlined manner. The first flange intermediate first end surface 25c curves from the first flange inner first end surface 25a and extends in a streamlined manner toward the first flange outer end surface 24 so that no corner (corner point) is formed between the first flange inner first end surface 25a and the first flange intermediate first end surface 25c. The first flange intermediate first end surface 25c curves from the first flange outer first end surface 25b and extends in a streamlined manner toward the first flange inner end surface 23 so that no corner (corner point) is formed between the first flange outer first end surface 25b and the first flange intermediate first end surface 25c. In a cross section perpendicular to the first direction D1 (the cross section shown in FIG. 6 ), the first flange intermediate first end surface 25c may or may not have a linearly extending portion.

[0052] Furthermore, the first flange portion intermediate second end face 26c is smoothly connected to the first flange portion inner second end face 26a and the first flange portion outer second end face 26b. The phrase "the first flange portion intermediate second end face 26c is smoothly connected to the first flange portion inner second end face 26a and the first flange portion outer second end face 26b" means that there are no corners (corner points) at the connection positions of the first flange portion intermediate second end face 26c and the first flange portion inner second end face 26a and the first flange portion outer second end face 26b, and that the first flange portion intermediate second end face 26c is connected to the first flange portion inner second end face 26a and the first flange portion outer second end face 26b in a streamlined manner. The first flange intermediate second end surface 26c curves from the first flange inner second end surface 26a and extends in a streamlined manner toward the first flange outer end surface 24 so that no corner (corner point) is formed between the first flange inner second end surface 26a and the first flange outer second end surface 26c. The first flange intermediate second end surface 26c curves from the first flange outer second end surface 26b and extends in a streamlined manner toward the first flange inner end surface 23 so that no corner (corner point) is formed between the first flange inner second end surface 26c and the first flange outer second end surface 26b. In a cross section perpendicular to the first direction D1 (the cross section shown in FIG. 6 ), the first flange intermediate second end surface 26c may or may not have a linearly extending portion.

[0053] Each of the first flange first end face 25 and the first flange second end face 26 has no corners (corner points) in a cross section perpendicular to the first direction D1 (the cross section shown in FIG. 6 ). The maximum curvature of each of the first flange first end face 25 and the first flange second end face 26 in a cross section perpendicular to the first direction D1 is, for example, 0.1 or less, preferably 0.06 or less, and more preferably 0.04 or less.

[0054] In addition, when the first flange inner end face 23 and the first flange outer end face 24 are formed in a curved shape, the first flange inner end face 23 can be, for example, a curved surface concentric with the inner peripheral surface of the stator 2, and the first flange outer end face 24 can be, for example, a curved surface concentric with the outer peripheral surface of the stator 2.

[0055] The second flange 30 is formed in a plate shape and protrudes from the tooth 10 in a direction perpendicular to the first direction D1. The second flange 30 protrudes from the tooth 10 when viewed from the first direction D1. The second flange 30 also protrudes from one end of the tooth 10 in the first direction D1 in directions along the second direction D2 and the third direction D3.

[0056] The second flange portion 30 has a second flange portion outer surface 31 and a second flange portion inner surface 32 that face the first direction D1. The second flange portion outer surface 31 is a surface that faces the opposite side from the first flange portion 20 in the first direction D1. The second flange portion inner surface 32 is a surface that faces the first flange portion 20 side in the first direction D1 and to which the teeth portion 10 is connected. The second flange portion outer surface 31 and the second flange portion inner surface 32 are arranged parallel to each other and formed into planar shapes that extend in the second direction D2 and the third direction D3.

[0057] The second flange 30 is composed of a second flange inner end face 33 and a second flange outer end face 34 facing the second direction D2, and a second flange first end face 35 and a second flange second end face 36 connected to the second flange inner end face 33 and the second flange outer end face 34 and facing the third direction D3. The second flange inner end face 33 is a surface facing the shaft hole 8 side of the stator core 5 (the radially inner side of the stator core 5). The second flange outer end face 34 is a surface facing the opposite side of the stator core 5 from the shaft hole 8 (the radially outer side of the stator core 5).

[0058] The second flange inner end surface 33 and the second flange outer end surface 34 are formed in a flat or curved shape. When the second flange inner end surface 33 and the second flange outer end surface 34 are formed in a flat shape, the second flange inner end surface 33 and the second flange outer end surface 34 are, for example, arranged parallel to each other and extending linearly in the third direction D3. In other words, the second flange inner end surface 33 and the second flange outer end surface 34 are formed in a flat shape extending along the first direction D1 and the third direction D3. When the second flange inner end surface 33 and the second flange outer end surface 34 are formed in a curved shape, for example, convex outward. In this embodiment, the second flange inner end face 33 and the second flange outer end face 34 are described as being formed in a planar shape extending along the first direction D1 and the third direction D3. Therefore, in this embodiment, the second flange inner end face 33 and the second flange outer end face 34 are arranged parallel to the teeth inner side surface 13 and the teeth outer side surface 14 of the teeth portion 10. The second flange inner end face 33 is formed shorter in the third direction D3 than the second flange outer end face 34. In other words, the length of the second flange inner end face 33 in the third direction D3 is shorter than the length of the second flange outer end face 34 in the third direction D3.

[0059] The second flange first end face 35 has a second flange inner first end face 35a connected to the second flange inner end face 33, a second flange outer first end face 35b connected to the second flange outer end face 34, and a second flange intermediate first end face 35c connected to the second flange inner first end face 35a and the second flange outer first end face 35b.

[0060] The second flange second end face 36 has a second flange inner second end face 36a connected to the second flange inner end face 33, a second flange outer second end face 36b connected to the second flange outer end face 34, and a second flange intermediate second end face 36c connected to the second flange inner second end face 36a and the second flange outer second end face 36b.

[0061] The second flange inner first end face 35a and the second flange inner second end face 36a are arranged parallel to each other. The second flange inner first end face 35a is formed in a planar shape and extends linearly in the second direction D2 from one edge of the second flange inner end face 33 in the third direction D3. The second flange inner second end face 36a is formed in a planar shape and extends linearly in the second direction D2 from the edge of the second flange inner end face 33 opposite the second flange inner first end face 35a in the third direction D3.

[0062] The second flange outer first end face 35b and the second flange outer second end face 36b are arranged parallel to each other. The second flange outer first end face 35b is formed in a planar shape and extends linearly in the second direction D2 from one edge of the second flange outer end face 34 in the third direction D3. The second flange outer second end face 36b is formed in a planar shape and extends linearly in the second direction D2 from the edge of the second flange outer end face 34 on the opposite side in the third direction D3 from the second flange outer first end face 35b.

[0063] The distance between the second flange intermediate first end face 35c and the second flange intermediate second end face 36c in the third direction D3 becomes narrower from the second flange outer end face 34 side toward the second flange inner end face 33 side. In other words, the second flange 30 becomes narrower at the second flange intermediate first end face 35c and the second flange intermediate second end face 36c from the second flange outer end face 34 side toward the second flange inner end face 33 side.

[0064] The second flange intermediate first end face 35c is smoothly connected to the second flange inner first end face 35a and the second flange outer first end face 35b. The smooth connection of the second flange intermediate first end face 35c with the second flange inner first end face 35a and the second flange outer first end face 35b means that there are no corners (corner points) at the connection positions of the second flange intermediate first end face 35c with the second flange inner first end face 35a and the second flange outer first end face 35b, and that the second flange intermediate first end face 35c with the second flange inner first end face 35a and the second flange outer first end face 35b are connected in a streamlined manner. The second flange intermediate first end surface 35c curves from the second flange inner first end surface 35a and extends in a streamlined manner toward the second flange outer end surface 34 so as to avoid forming a corner (corner point) between the second flange intermediate first end surface 35c and the second flange inner first end surface 35a. The second flange intermediate first end surface 35c curves from the second flange outer first end surface 35b and extends in a streamlined manner toward the second flange inner end surface 33 so as to avoid forming a corner (corner point) between the second flange intermediate first end surface 35c and the second flange outer first end surface 35b. In a cross section perpendicular to the first direction D1 (the cross section shown in FIG. 8 ), the second flange intermediate first end surface 35c may or may not have a linearly extending portion.

[0065] Furthermore, the second flange intermediate second end face 36c is smoothly connected to the second flange inner second end face 36a and the second flange outer second end face 36b. The smooth connection of the second flange intermediate second end face 36c with the second flange inner second end face 36a and the second flange outer second end face 36b means that there are no corners (corner points) at the connection positions of the second flange intermediate second end face 36c with the second flange inner second end face 36a and the second flange outer second end face 36b, and that the second flange intermediate second end face 36c with the second flange inner second end face 36a and the second flange outer second end face 36b are connected in a streamlined manner. The second flange intermediate second end surface 36c curves from the second flange inner second end surface 36a and extends in a streamlined manner toward the second flange outer end surface 34 so as to avoid forming a corner (corner point) between the second flange intermediate second end surface 36c and the second flange outer second end surface 36b. The second flange intermediate second end surface 36c curves from the second flange outer second end surface 36b and extends in a streamlined manner toward the second flange inner end surface 33 so as to avoid forming a corner (corner point) between the second flange intermediate second end surface 36c and the second flange outer second end surface 36b. In a cross section perpendicular to the first direction D1 (the cross section shown in FIG. 8 ), the second flange intermediate second end surface 36c may or may not have a linearly extending portion.

[0066] Each of the second flange first end face 35 and the second flange second end face 36 has no corners (corner points) in a cross section perpendicular to the first direction D1 (the cross section shown in FIG. 8 ). The maximum curvature of each of the second flange first end face 35 and the second flange second end face 36 in a cross section perpendicular to the first direction D1 is, for example, 0.1 or less, preferably 0.06 or less, and more preferably 0.04 or less.

[0067] In addition, when the second flange inner end face 33 and the second flange outer end face 34 are formed in a curved shape, the second flange inner end face 33 can be, for example, a curved surface concentric with the inner peripheral surface of the stator 2, and the second flange outer end face 34 can be, for example, a curved surface concentric with the outer peripheral surface of the stator 2.

[0068] The first flange portion 20 and the second flange portion 30 have the same shape. The first flange portion 20 and the second flange portion 30 are disposed at the same position in the second direction D2 and the third direction D3. That is, the first flange inner end face 23 of the first flange portion 20 and the second flange inner end face 33 of the second flange portion 30 are disposed at the same position in the second direction D2. The first flange outer end face 24 of the first flange portion 20 and the second flange outer end face 34 of the second flange portion 30 are disposed at the same position in the second direction D2. The first flange first end face 25 of the first flange portion 20 and the second flange first end face 35 of the second flange portion 30 are disposed at the same position in the third direction D3. Furthermore, the first flange second end surface 26 of the first flange 20 and the second flange second end surface 36 of the second flange 30 are disposed at the same position in the third direction D3.

[0069] Next, an example of a method for manufacturing the core piece 7 will be described.

[0070] In one example of a method for manufacturing the core piece 7, a powder supplying process, a pressing process, and a removal process are performed in this order using a core piece manufacturing apparatus 100 shown in Figures 9 to 11. Figures 9 to 11 are cross-sectional views showing the core piece manufacturing apparatus. As shown in Figures 9 to 11, the core piece manufacturing apparatus 100 includes a die 110 having a molding hole 111 formed therein, a first lower punch 120 and a first upper punch 130 (see Figure 9) for forming the teeth portion 10 of the core piece 7, a second lower punch 140 and a second upper punch 150 (see Figure 10) for forming the first flange portion 20 of the core piece 7, and a third lower punch 160 and a third upper punch 170 (see Figure 11) for forming the second flange portion 30 of the core piece 7.

[0071] The forming hole 111 is a hole that penetrates the die 110 in the up-down direction UD. The forming hole 111 is composed of a core piece cavity 112 having a shape corresponding to the core piece 7, a lower punch hole 113 that penetrates from the lower end surface of the core piece cavity 112 to the lower end surface of the die 110 on the same cross section, and an upper punch hole 114 that penetrates from the upper end surface of the core piece cavity 112 to the upper end surface of the die 110 on the same cross section. The core piece cavity 112 is a space corresponding to the core piece 7, with the teeth inner surface 13, first flange inner end surface 23, and second flange inner end surface 33 facing downward D, and the teeth outer surface 14, first flange outer end surface 24, and second flange outer end surface 34 facing upward U. The lower punch hole 113 is a space having the same cross section as the tooth inner surface 13, the first flange inner end surface 23, and the second flange inner end surface 33. The upper punch hole 114 is a space having the same cross section as the tooth outer surface 14, the first flange outer end surface 24, and the second flange outer end surface 34.

[0072] In the powder supplying step, the first lower punch 120, the second lower punch 140, and the third lower punch 160 are inserted into the lower punch holes 113 of the molding hole 111 from below D. Then, soft magnetic powder 9 coated with an insulating material is supplied from above U into the molding hole 111.

[0073] In the pressing process, the first upper punch 130, the second upper punch 150, and the third upper punch 170 are inserted from above U into the upper punch holes 114 of the forming hole 111. Then, the soft magnetic powder 9 supplied to the forming hole 111 is pressed by at least one of moving the first lower punch 120, the second lower punch 140, and the third lower punch 160 upward U and moving the first upper punch 130, the second upper punch 150, and the third upper punch 170 downward D. The soft magnetic powder 9 supplied to the forming hole 111 is pressed between the first lower punch 120 and the first upper punch 130 to form the teeth portions 10 of the core pieces 7. Furthermore, the soft magnetic powder 9 is pressed between the second lower punch 140 and the second upper punch 150 to form the first flange portions 20 of the core pieces 7. Furthermore, the soft magnetic powder 9 is pressed between the third lower punch 160 and the third upper punch 170, thereby being formed in the second flange portion 30 of the core piece 7. In this way, the core piece 7 is formed as a green compact obtained by pressing the soft magnetic powder 9.

[0074] In the ejection step, the first upper punch 130, the second upper punch 150, and the third upper punch 170 are ejected upward U from the forming hole 111, and the first lower punch 120, the second lower punch 140, and the third lower punch 160 are moved upward U, thereby ejecting the core piece 7 from the forming hole 111. In this way, the core piece 7 is obtained.

[0075] As described above, in this core piece 7, the tooth inner first side surface 15a and the tooth inner second side surface 16a connected to the tooth inner surface 13 are parallel to each other, and the tooth outer first side surface 15b and the tooth outer second side surface 16b connected to the tooth outer surface 14 are parallel to each other. This facilitates powder compaction. The tooth intermediate first side surface 15c is smoothly connected to the tooth inner first side surface 15a and the tooth outer first side surface 15b, and the tooth intermediate second side surface 16c is smoothly connected to the tooth inner second side surface 16a and the tooth outer second side surface 16b. In other words, there are no corners at the connection positions between the tooth intermediate first side surface 15c and the tooth inner first side surface 15a and the tooth outer first side surface 15b, and there are no corners at the connection positions between the tooth intermediate second side surface 16c and the tooth inner second side surface 16a and the tooth outer second side surface 16b. Therefore, when the core pieces 7 are compacted, the soft magnetic powder 9 can flow smoothly around the connection positions between the teeth intermediate first side surface 15c and the teeth inner first side surface 15a and the teeth outer first side surface 15b, and around the connection positions between the teeth intermediate second side surface 16c and the teeth inner second side surface 16a and the teeth outer second side surface 16b. This makes it possible to suppress variations in density of the core pieces 7, thereby improving the characteristics of the axial gap motor 1.

[0076] Furthermore, in this core piece 7, the teeth first side surface 15 and the teeth second side surface 16 have no corners in a cross section perpendicular to the first direction D1, so that when the core piece 7 is compacted, the soft magnetic powder 9 can flow smoothly along the teeth first side surface 15 and the teeth second side surface 16. This makes it possible to further suppress variations in density of the core piece 7, thereby further improving the characteristics of the axial gap motor 1.

[0077] Furthermore, in this core piece 7, the maximum curvature of the teeth first side surface 15 and the teeth second side surface 16 in a cross section perpendicular to the first direction D1 is 0.1 or less, preferably 0.06 or less, and more preferably 0.04 or less, so that when the core piece 7 is compacted, the soft magnetic powder 9 can flow smoothly along the teeth first side surface 15 and the teeth second side surface 16. This can further suppress variations in density of the core piece 7, thereby further improving the characteristics of the axial gap motor 1.

[0078] Furthermore, in this core piece 7, when the tooth inner surface 13 and the tooth outer surface 14 are curved, the tooth inner surface 13 is a curved surface concentric with the inner peripheral surface of the stator 2, and the tooth outer surface 14 is a curved surface concentric with the outer peripheral surface of the stator 2, so that the tooth inner surface 13 and the tooth outer surface 14 have gently curved surfaces. Therefore, when the core piece 7 is compacted, the soft magnetic powder 9 can flow smoothly along the tooth inner surface 13 and the tooth outer surface 14. This can further suppress variations in density of the core piece 7, thereby further improving the characteristics of the axial gap motor 1.

[0079] In this core piece 7, the first flange inner first end face 25a and the first flange inner second end face 26a, which are connected to the first flange inner end face 23, are parallel to each other, and the first flange outer first end face 25b and the first flange outer second end face 26b, which are connected to the first flange outer end face 24, are parallel to each other. This facilitates powder compaction. The first flange intermediate first end face 25c is smoothly connected to the first flange inner first end face 25a and the first flange outer first end face 25b, and the first flange intermediate second end face 26c is smoothly connected to the first flange inner second end face 26a and the first flange outer second end face 26b. That is, no corners are formed at the connection positions between the first flange intermediate first end face 25c and the first flange inner first end face 25a and the first flange outer first end face 25b, and no corners are formed at the connection positions between the first flange intermediate second end face 26c and the first flange inner second end face 26a and the first flange outer second end face 26b. Therefore, when the core pieces 7 are compacted, the soft magnetic powder 9 can flow smoothly around the connection positions between the first flange intermediate first end face 25c and the first flange inner first end face 25a and the first flange outer first end face 25b, and around the connection positions between the first flange intermediate second end face 26c and the first flange inner second end face 26a and the first flange outer second end face 26b. This suppresses density variations in the core pieces 7, thereby improving the characteristics of the axial gap motor 1.

[0080] Furthermore, in this core piece 7, the first flange first end face 25 and the first flange second end face 26 have no corners in a cross section perpendicular to the first direction D1, so that when the core piece 7 is compacted, the soft magnetic powder 9 can flow smoothly along the first flange first end face 25 and the first flange second end face 26. This makes it possible to further suppress variations in density of the core piece 7, thereby further improving the characteristics of the axial gap motor 1.

[0081] Furthermore, in this core piece 7, the maximum curvature of the first flange first end face 25 and the first flange second end face 26 in a cross section perpendicular to the first direction D1 is 0.1 or less, preferably 0.06 or less, and more preferably 0.04 or less, so that when the core piece 7 is compacted, the soft magnetic powder 9 can flow smoothly along the first flange first end face 25 and the first flange second end face 26. This can further suppress variations in density of the core piece 7, thereby further improving the characteristics of the axial gap motor 1.

[0082] Furthermore, in this core piece 7, when the first flange inner end face 23 and the first flange outer end face 24 are formed in a curved shape, the first flange inner end face 23 is a curved surface concentric with the inner peripheral surface of the stator 2, and the first flange outer end face 24 is a curved surface concentric with the outer peripheral surface of the stator 2, so that the first flange inner end face 23 and the first flange outer end face 24 have gently curved surfaces. Therefore, when the core piece 7 is compacted, the soft magnetic powder 9 can flow smoothly along the first flange inner end face 23 and the first flange outer end face 24. This can further suppress variations in density of the core piece 7, thereby further improving the characteristics of the axial gap motor 1.

[0083] In this core piece 7, the second flange inner first end face 35a and the second flange inner second end face 36a, which are connected to the second flange inner end face 33, are parallel to each other, and the second flange outer first end face 35b and the second flange outer second end face 36b, which are connected to the second flange outer end face 34, are parallel to each other. This facilitates powder compaction. The second flange intermediate first end face 35c is smoothly connected to the second flange inner first end face 35a and the second flange outer first end face 35b, and the second flange intermediate second end face 36c is smoothly connected to the second flange inner second end face 36a and the second flange outer second end face 36b. That is, no corners are formed at the connection positions between the second flange intermediate first end face 35c and the second flange inner first end face 35a and the second flange outer first end face 35b, and no corners are formed at the connection positions between the second flange intermediate second end face 36c and the second flange inner second end face 36a and the second flange outer second end face 36b. Therefore, when the core pieces 7 are compacted, the soft magnetic powder 9 can flow smoothly around the connection positions between the second flange intermediate first end face 35c and the second flange inner first end face 35a and the second flange outer first end face 35b, and around the connection positions between the second flange intermediate second end face 36c and the second flange inner second end face 36a and the second flange outer second end face 36b. This suppresses density variations in the core pieces 7, thereby improving the characteristics of the axial gap motor 1.

[0084] Furthermore, in this core piece 7, the second flange first end face 35 and the second flange second end face 36 have no corners in a cross section perpendicular to the first direction D1, so that when the core piece 7 is compacted, the soft magnetic powder 9 can flow smoothly along the second flange first end face 35 and the second flange second end face 36. This makes it possible to further suppress variations in density of the core piece 7, thereby further improving the characteristics of the axial gap motor 1.

[0085] Furthermore, in this core piece 7, the maximum curvature of the second flange first end face 35 and the second flange second end face 36 in a cross section perpendicular to the first direction D1 is 0.1 or less, preferably 0.06 or less, and more preferably 0.04 or less, so that when the core piece 7 is compacted, the soft magnetic powder 9 can flow smoothly along the second flange first end face 35 and the second flange second end face 36. This can further suppress variations in density of the core piece 7, thereby further improving the characteristics of the axial gap motor 1.

[0086] Furthermore, in this core piece 7, when the second flange inner end face 33 and the second flange outer end face 34 are formed as curved surfaces, the second flange inner end face 33 is a curved surface concentric with the inner peripheral surface of the stator 2, and the second flange outer end face 34 is a curved surface concentric with the outer peripheral surface of the stator 2, so that the second flange inner end face 33 and the second flange outer end face 34 have gently curved surfaces. Therefore, when the core piece 7 is compacted, the soft magnetic powder 9 can flow smoothly along the second flange inner end face 33 and the second flange outer end face 34. This can further suppress variations in density of the core piece 7, thereby further improving the characteristics of the axial gap motor 1.

[0087] Furthermore, in this core piece 7, the first flange portion 20 and the second flange portion 30 have the same shape, so that the mold for powder compacting the core piece 7 can have a simpler shape, which further reduces the manufacturing cost of the core piece 7.

[0088] The stator core 5 according to this embodiment includes the above-described core pieces 7, and therefore the characteristics of the axial gap motor 1 can be improved.

[0089] The stator 2 according to this embodiment includes the stator core 5 described above, and therefore the characteristics of the axial gap motor 1 can be improved.

[0090] The axial gap motor 1 according to this embodiment includes the stator 2 described above, and therefore the characteristics of the axial gap motor 1 can be improved.

[0091] The present disclosure is not limited to the above-described embodiments, and modifications can be made as appropriate without departing from the spirit of the present disclosure.

[0092] For example, in the above embodiment, the first flange first end face has a first flange intermediate first end face that is smoothly connected to the first flange inner first end face and the first flange outer first end face, and the first flange second end face has a first flange intermediate second end face that is smoothly connected to the first flange inner second end face and the first flange outer second end face. However, the first flange first end face and the first flange second end face may not have such a first flange intermediate first end face and first flange intermediate second end face.

[0093] Similarly, in the above embodiment, the second flange first end face has a second flange intermediate first end face that is smoothly connected to the second flange inner first end face and the second flange outer first end face, and the second flange second end face has a second flange intermediate second end face that is smoothly connected to the second flange inner second end face and the second flange outer second end face. However, the second flange first end face and the second flange second end face may not have such a second flange intermediate first end face and second flange intermediate second end face.

[0094] The present disclosure can be used as a core piece, a stator core, a stator, and an axial gap motor.

[0095] REFERENCE SIGNS LIST 1...axial gap motor, 2...stator, 3...rotor, 4...shaft, 5...stator core, 6...winding, 7...core piece, 8...shaft hole, 9...soft magnetic powder, 10...teeth portion, 11...circumferential surface, 13...teeth portion inner surface, 14...teeth portion outer surface, 15...teeth portion first side surface, 15a...teeth portion inner first side surface, 15b...teeth portion outer first side surface, 15c...teeth portion intermediate first side surface, 16...teeth portion second side surface, 16a... second side surface inside the teeth portion, 16b... second side surface outside the teeth portion, 16c... second intermediate side surface inside the teeth portion, 20... first flange portion, 21... outer surface of the first flange portion, 22... inner surface of the first flange portion, 23... inner end surface of the first flange portion, 24... outer end surface of the first flange portion, 25... first end face of the first flange portion, 25a... first inner first end face of the first flange portion, 25b... outer first end face of the first flange portion, 25c... intermediate first end face of the first flange portion, 26... second end face of the first flange portion, 26a... second inner end face of the first flange portion , 26b...First flange outer second end surface, 26c...First flange intermediate second end surface, 30...Second flange, 31...Second flange outer surface, 32...Second flange inner surface, 33...Second flange inner end surface, 34...Second flange outer end surface, 35...Second flange first End surface, 35a... Second flange inner first end surface, 35b... Second flange outer first end surface, 35c... Second flange intermediate first end surface, 36... Second flange second end surface, 36a... Second flange inner second end surface, 36b... Second flange outer second end surface, 36 c...second flange intermediate second end surface, 100...core piece manufacturing apparatus, 110...die, 111...forming hole, 112...core piece cavity, 113...lower punch hole, 114...upper punch hole, 120...first lower punch, 130...first upper punch, 140...second lower punch, 150...second upper punch, 160...third lower punch, 170...third upper punch, D1...first direction, D2...second direction, D3...third direction, UD...upper and lower direction, D...downward, U...upward.

Claims

1. A core piece of a stator core for an axial gap motor, made by pressing soft magnetic powder coated with an insulating material, comprising: teeth portions having peripheral surfaces extending in a first direction and around which windings are wound; first flange portions arranged on one side of the teeth portions in the first direction; and second flange portions arranged on the opposite side of the teeth portions from the first flange portions in the first direction, wherein the teeth portions have teeth inner and outer side surfaces facing each other in a second direction perpendicular to the first direction, and teeth first and second side surfaces connected to the teeth inner and outer side surfaces, wherein the teeth first side surfaces have: teeth inner first side surfaces connected to the teeth inner side surfaces; teeth outer first side surfaces connected to the teeth outer side surfaces; and teeth intermediate first side surfaces smoothly connected to the teeth inner first side surfaces and the teeth outer first side surfaces, wherein the teeth second side surfaces are a teeth inner second side surface connected to the teeth inner surface and parallel to the teeth inner first side surface; a teeth outer second side surface connected to the teeth outer surface and parallel to the teeth outer first side surface; and a teeth intermediate second side surface smoothly connected to the teeth inner second side surface and the teeth outer second side surface.

2. A core piece according to claim 1, wherein the first side surface of the teeth and the second side surface of the teeth have no corners in a cross section perpendicular to the first direction.

3. A core piece according to claim 1 or 2, wherein the maximum curvature of the first side surface of the teeth and the second side surface of the teeth in a cross section perpendicular to the first direction is 0.1 or less.

4. The first flange portion has a first flange portion inner end face and a first flange portion outer end face facing in the second direction, and a first flange portion first end face and a first flange portion second end face connected to the first flange portion inner end face and the first flange portion outer end face, the first flange portion first end face having a first flange portion inner first end face connected to the first flange portion inner end face, a first first flange portion outer first end face connected to the first flange portion outer end face, and a first first flange portion intermediate first end face smoothly connected to the first first flange portion inner first end face and the first flange portion outer first end face, the first flange portion second end face having a first flange portion inner second end face connected to the first flange portion inner end face and parallel to the first first flange portion inner first end face, and a first flange portion outer second end face connected to the first flange portion outer end face and parallel to the first first flange portion outer first end face, The core piece according to any one of claims 1 to 3, further comprising: a first flange portion intermediate second end surface smoothly connected to the first flange portion inner second end surface and the first flange portion outer second end surface.

5. A core piece according to claim 4, wherein the first end face of the first flange portion and the second end face of the first flange portion have no corners in a cross section perpendicular to the first direction.

6. A core piece according to claim 4 or 5, wherein the maximum curvature of the first end face of the first flange portion and the second end face of the first flange portion in a cross section perpendicular to the first direction is 0.1 or less.

7. The second flange has a second flange inner end surface and a second flange outer end surface facing in the second direction, and a second flange first end surface and a second flange second end surface connected to the second flange inner end surface and the second flange outer end surface, the second flange first end surface having a second flange inner first end surface connected to the second flange inner end surface, a second flange outer first end surface connected to the second flange outer end surface, and a second flange intermediate first end surface smoothly connected to the second flange inner first end surface and the second flange outer first end surface, the second flange second end surface having a second flange inner second end surface connected to the second flange inner end surface and parallel to the second flange inner first end surface, and a second flange outer second end surface connected to the second flange outer end surface and parallel to the second flange outer first end surface, The core piece according to any one of claims 1 to 6, further comprising: a second flange intermediate second end surface smoothly connected to the second flange inner second end surface and the second flange outer second end surface.

8. A core piece according to claim 7, wherein the first end face of the second flange portion and the second end face of the second flange portion have no corners in a cross section perpendicular to the first direction.

9. A core piece according to claim 7 or 8, wherein the maximum curvature of the cross section of the first end face of the second flange portion and the second end face of the second flange portion perpendicular to the first direction is 0.1 or less.

10. A core piece according to any one of claims 1 to 9, wherein the first flange portion and the second flange portion have the same shape.

11. A stator core for an axial gap motor, comprising a core piece according to any one of claims 1 to 10.

12. A stator for an axial gap motor, comprising: a stator core according to claim 11; and a winding wound around the core pieces of the stator core.

13. An axial gap motor comprising: the stator according to claim 12; and a rotor arranged rotatably relative to the stator.

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