Member, stator core, stator, and rotary electric machine

Abstract

To provide a core piece that can form an axial gap rotary electric machine having excellent magnetic properties.SOLUTION: A core piece in which a columnar first member and a plate-like second member are formed of a powder molded body by integration molding, the powder molded body has a plurality of flat soft magnetic particles, a first average aspect ratio of the soft magnetic particles in a first cross section of the first member is 1.2 or higher, and a second average ratio of the soft magnetic particles in a second cross section of the second member is 1.2 or higher.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a core piece, a stator core, a stator, a rotating electric machine, and a method for manufacturing a core piece. This application claims priority based on Japanese Patent Application No. 2020-082831, filed on May 8, 2020, and incorporates by reference all of the contents of said Japanese application. [Background technology]

[0002] Patent Document 1 discloses a stator core for an axial gap motor. The stator core includes a yoke portion and teeth. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-44829 A Summary of the Invention

[0004] The core pieces according to the present disclosure are arranged in an annular manner to construct a stator core of an axial gap type rotating electric machine, and include a columnar first member extending in an axial direction of the stator core, and a plate-shaped second member provided on a first end side of the first member in the axial direction of the stator core, and the first member and the second member are configured as an integrally molded powder compact, and the powder compact has a plurality of soft magnetic particles, the soft magnetic particles having a flat shape, and in a first cross section of the first member along the axial and radial directions of the stator core, a first average aspect ratio of the soft magnetic particles is 1.2 or more, and in a second cross section of the second member perpendicular to the axial direction of the stator core, The soft magnetic particles have a second average aspect ratio of 1.2 or more, the first average aspect ratio being the ratio L12 / L11 of the average length L11 to the average length L12 in the first cross section, the second average aspect ratio being the ratio L22 / L21 of the average length L21 to the average length L22 in the second cross section, the average length L11 being the average length of the soft magnetic particles along the radial direction of the stator core, the average length L12 being the average length of the soft magnetic particles along the axial direction of the stator core, the average length L21 being the average length of the soft magnetic particles along the radial direction of the stator core, and the average length L22 being the average length of the soft magnetic particles along the circumferential direction of the stator core.

[0005] The stator core according to the present disclosure is a stator core for an axial gap type rotating electric machine, and has a plurality of core pieces arranged in an annular shape, each of the plurality of core pieces being a core piece according to the present disclosure.

[0006] The stator according to the present disclosure is a stator for an axial gap type rotating electric machine, and includes a stator core according to the present disclosure and a coil disposed in each of the first members of the stator core.

[0007] The rotating electric machine according to the present disclosure is an axial gap type rotating electric machine including a rotor and a stator, the stator being the stator according to the present disclosure.

[0008] The manufacturing method of a core piece according to the present disclosure is a manufacturing method of core pieces arranged in a ring to construct a stator core of an axial gap type rotating electric machine, and includes a step of filling a raw material powder containing a plurality of spherical soft magnetic particles into a die, and a step of compressing the raw material powder in the die to form a molded body, wherein the core piece includes a columnar first member extending in the axial direction of the stator core, and a plate-shaped second member provided on a first end side of the first member in the axial direction of the stator core, and the direction in which the raw material powder is compressed is along the radial direction of the stator core. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing an outline of a core piece according to the first embodiment. [Diagram 2] FIG. 2 is a top view showing an outline of a core piece according to the first embodiment. [Diagram 3] FIG. 3 is a view of the core piece according to the first embodiment as viewed from the inner peripheral surface side. [Figure 4] FIG. 4 is a cross-sectional view of the core piece shown in FIG. 3 taken along line IV-IV. [Diagram 5] 5 is a cross-sectional view of the core piece shown in FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI of the core piece shown in FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII of the core piece shown in FIG. [Figure 8] FIG. 8 is an enlarged view showing the outline of the area surrounded by the dashed circle in FIG. [Figure 9] FIG. 9 is an enlarged view showing the outline of the area surrounded by the dashed circle in FIG. [Figure 10] FIG. 10 is a cross-sectional view of the core piece shown in FIG. 2 taken along line XX. [Figure 11] FIG. 11 is a top view showing an opening edge of a die of a metal mold for producing a core piece according to the first embodiment. [Figure 12] FIG. 12 is a cross-sectional view showing an outline of a die for manufacturing a first member in the core piece according to the first embodiment. [Figure 13] FIG. 13 is a cross-sectional view showing an outline of a die for manufacturing a second member in the core piece according to the first embodiment. [Figure 14] FIG. 14 is a cross-sectional view showing an outline of a die for manufacturing a third member in the core piece according to the first embodiment. [Figure 15] FIG. 15 is a perspective view showing an outline of a core piece according to the second embodiment. [Figure 16] FIG. 16 is a perspective view showing an outline of a stator core according to the third embodiment. [Figure 17] FIG. 17 is a perspective view showing an outline of a stator according to the fourth embodiment. [Figure 18] FIG. 18 is a cross-sectional view showing an outline of a rotating electric machine according to the fifth embodiment. [Figure 19] FIG. 19 is a cross-sectional view showing an outline of a rotating electric machine according to the sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Problem that this disclosure aims to solve] It is desirable to improve the magnetic characteristics of an axial gap type rotating electric machine.

[0011] An object of the present disclosure is to provide a core piece, a stator core, and a stator that can be used to construct an axial gap type rotating electric machine with excellent magnetic properties. Another object of the present disclosure is to provide a rotating electric machine with excellent magnetic properties. Another object of the present disclosure is to provide a method for manufacturing the core pieces that can manufacture the core pieces.

[0012] [Effects of this disclosure] The core pieces, stator core, and stator according to the present disclosure can be used to construct an axial gap type rotating electric machine with excellent magnetic properties. The rotating electric machine according to the present disclosure has excellent magnetic properties. The manufacturing method of the core pieces according to the present disclosure can manufacture core pieces that can be used to construct an axial gap type rotating electric machine with excellent magnetic properties.

[0013] Description of the embodiments of the present disclosure First, the embodiments of the present disclosure will be listed and described.

[0014] (1) A core piece according to one embodiment of the present disclosure is a core piece arranged in an annular shape to construct a stator core of an axial gap type rotating electric machine, the core piece comprising: a columnar first member extending in an axial direction of the stator core; and a plate-shaped second member provided on a first end side of the first member in the axial direction of the stator core, the first member and the second member being configured as an integrally molded powder compact, the powder compact having a plurality of soft magnetic particles, the soft magnetic particles being flat, a first average aspect ratio of the soft magnetic particles being 1.2 or more in a first cross section of the first member along the axial and radial directions of the stator core, and a second average aspect ratio of the soft magnetic particles being 1.2 or more in a second cross section of the second member perpendicular to the axial direction of the stator core. In the present invention, a second average aspect ratio of the soft magnetic particles is 1.2 or more, the first average aspect ratio is the ratio L12 / L11 of the average length L11 to the average length L12 in the first cross section, the second average aspect ratio is the ratio L22 / L21 of the average length L21 to the average length L22 in the second cross section, the average length L11 is the average length of the soft magnetic particles along the radial direction of the stator core, the average length L12 is the average length of the soft magnetic particles along the axial direction of the stator core, the average length L21 is the average length of the soft magnetic particles along the radial direction of the stator core, and the average length L22 is the average length of the soft magnetic particles along the circumferential direction of the stator core.

[0015] The above core pieces can be used to construct an axial gap type rotating electric machine with excellent magnetic properties. This is because, in both the first and second members, the soft magnetic particles are oriented in the direction in which the magnetic flux passes, and the number of grain boundaries that become magnetic gaps is small. The details of the reasons are as follows.

[0016] When an axial gap type rotating electric machine is constructed using the above core pieces, magnetic flux passes through the core pieces. The magnetic flux passes through the second member and then the first member. Alternatively, the magnetic flux passes through the first member and then the second member. Regardless of the order in which the magnetic flux passes, the magnetic flux passing through the first member is aligned along the extension direction of the first member, i.e., the axial direction of the stator core. The magnetic flux passing through the second member is aligned along the surface direction of the second member, i.e., the circumferential direction of the stator core. Thus, in the core pieces, the magnetic flux passing through the first member and the magnetic flux passing through the second member are aligned along different directions.

[0017] The first member of the core pieces has a first average aspect ratio of 1.2 or more in a first cross section. That is, in the first cross section of the first member, the length of the soft magnetic particles along the axial direction of the stator core is longer than the length along the radial direction of the stator core. In other words, the length of the soft magnetic particles along the direction of the magnetic flux is longer than the length along the direction perpendicular to the direction of the magnetic flux.

[0018] The second member of the core piece has a second average aspect ratio of 1.2 or more in the second cross section. That is, in the second cross section of the second member, the length of the soft magnetic particles along the circumferential direction of the stator core is longer than the length along the radial direction of the stator core. In other words, the length of the soft magnetic particles along the direction of the magnetic flux is longer than the length along the direction perpendicular to the direction of the magnetic flux.

[0019] A first square observation field is taken at a first cross section of the first member. The first observation field is taken to have a pair of first sides along the axial direction of the stator core and a pair of second sides along the radial direction of the stator core. A second square observation field is taken at a second cross section of the second member. The second observation field is taken to have a pair of first sides along the radial direction of the stator core and a pair of second pieces along a direction perpendicular to the radial direction of the stator core.

[0020] When the first average aspect ratio of the soft magnetic particles is 1.2 or more, the number of soft magnetic particles arranged in parallel in the axial direction of the stator core is smaller than the number of soft magnetic particles arranged in parallel in the radial direction of the stator core in the first observation field. In other words, the number of soft magnetic particles arranged in parallel in the direction of the magnetic flux is smaller than the number of soft magnetic particles arranged in parallel in the direction perpendicular to the direction of the magnetic flux in the first observation field. That is, the number of grain boundaries dividing the axial direction of the stator core is smaller in the first observation field. In other words, the number of grain boundaries dividing the direction along the magnetic flux is smaller in the first observation field. The grain boundaries refer to the spaces between adjacent soft magnetic particles.

[0021] When the second average aspect ratio of the soft magnetic particles is 1.2 or more, the number of soft magnetic particles arranged in parallel in the circumferential direction of the stator core is smaller in the second observation field than the number of soft magnetic particles arranged in parallel in the radial direction of the stator core. In other words, the number of soft magnetic particles arranged in parallel in the direction of the magnetic flux is smaller in the second observation field than the number of soft magnetic particles arranged in parallel in the direction perpendicular to the direction of the magnetic flux. That is, the number of grain boundaries dividing the circumferential direction of the stator core is smaller in the second observation field. In other words, the number of grain boundaries dividing the direction along the magnetic flux is smaller in the second observation field.

[0022] This core piece is composed of a powder compact in which the first member and the second member are integrally molded. As will be described in detail later, such a core piece can be manufactured by adjusting the direction in which the raw material powder in the die is pressed and the direction in which the manufactured core piece is extracted from the die to the radial direction of the stator core in the core piece.

[0023] Conventionally, a core piece formed of a powder compact in which a first member and a second member are integrally molded is manufactured by applying pressure and drawing the core piece in a direction parallel to the axial direction of the stator core. Thus, the above-mentioned core piece and the conventional core piece have different applying pressure and drawing directions when manufacturing the core piece.

[0024] Conventional core piece green compacts are manufactured by pressurizing raw material powder filled in a die hole of a metal mold with an upper punch and a lower punch. The pressing direction is along the axial direction of the stator core in the core piece, i.e., the parallel direction of the first member and the second member. In the green compact, the first end side and second end side faces in the axial direction of the stator core are formed by the upper end face of the lower punch and the lower end face of the upper punch. In the green compact, the first direction side and second direction side faces in the circumferential direction of the stator core are formed by the inner peripheral surface of the lower punch. In the green compact, the outer peripheral side and inner peripheral side faces of the stator core are formed by the inner peripheral surface of the die hole. That is, the first end face in the axial direction of the first member and the first end face in the axial direction of the second member are formed by the upper end face of the lower punch. The second end face in the axial direction of the second member is formed by the lower end face of the upper punch. The first direction side and second direction side faces in the circumferential direction of the first member are formed by the inner peripheral surface of the lower punch. The outer peripheral surface and the inner peripheral surface of the first member and the second member are formed by the inner peripheral surface of the die hole. The direction in which the powder compact is removed from the die is the same as the pressing direction, and is the direction along the axial direction of the stator core in the core piece, i.e., the direction in which the first member and the second member are arranged side by side.

[0025] The magnetic flux passing through the first member of the conventional core piece is aligned along the axial direction of the stator core, as in the second member of the core piece described above. The magnetic flux passing through the second member of the conventional core piece is aligned along the circumferential direction of the stator core, as in the second member of the core piece described above.

[0026] In a first member of a conventional core piece, a first cross section is taken similar to the first cross section of the first member of the core piece. Also, in the first cross section of the conventional core piece, a first square observation field is taken similar to the first observation field described above. In a second member of a conventional core piece, a second cross section is taken similar to the second cross section of the second member of the core piece. Also, in the second cross section of the conventional core piece, a second square observation field is taken similar to the second observation field described above.

[0027] In the first cross section of the first member of the conventional core piece, unlike the first cross section of the first member of the core piece, the length of the soft magnetic particles along the axial direction of the stator core is shorter than the length along the radial direction of the stator core. Therefore, in the first observation field of the conventional core piece, unlike the first observation field of the core piece, the number of soft magnetic particles aligned in the axial direction of the stator core is greater than the number of soft magnetic particles aligned in the radial direction of the stator core. In other words, in the first observation field of the conventional core piece, unlike the first observation field of the core piece, the number of soft magnetic particles aligned in the direction of the magnetic flux is greater than the number of soft magnetic particles aligned in the direction perpendicular to the direction of the magnetic flux. That is, in the first observation field of the conventional core piece, unlike the first observation field of the core piece, the number of grain boundaries dividing the axial direction of the stator core is greater. In other words, in the first observation field of the conventional core piece, unlike the first observation field of the core piece, the number of grain boundaries dividing the direction along the magnetic flux is greater.

[0028] In the second cross section of the second member of the conventional core piece, unlike the second cross section of the second member of the core piece, the length of the soft magnetic particles along the circumferential direction of the stator core is approximately the same as the length along the radial direction of the stator core. Therefore, in the second observation field of the conventional core piece, unlike the second observation field of the core piece, the number of soft magnetic particles aligned in the circumferential direction of the stator core is approximately the same as the number of soft magnetic particles aligned in the radial direction of the stator core. In other words, in the second observation field of the conventional core piece, unlike the second observation field of the core piece, the number of grain boundaries dividing the circumferential direction of the stator core is approximately the same as the number of grain boundaries dividing the radial direction of the stator core. That is, in the second observation field of the conventional core piece, unlike the second observation field of the core piece, the number of soft magnetic particles aligned in the direction of the magnetic flux is approximately the same as the number of soft magnetic particles aligned in the direction perpendicular to the direction of the magnetic flux. In the second observation field of the conventional core piece, unlike the second observation field of the above-mentioned core piece, the number of grain boundaries that divide the direction along the magnetic flux is approximately the same as the number of grain boundaries that divide the direction perpendicular to the magnetic flux direction.

[0029] As described above, the first member of the core piece has a smaller number of grain boundaries that divide the direction along the magnetic flux than the first member of the conventional core piece. These grain boundaries become magnetic gaps. The larger the magnetic gap, the greater the magnetic resistance. Therefore, the first member of the core piece allows magnetic flux to pass through more easily than the first member of the conventional core piece. The ease of passage of magnetic flux through the second member of the core piece and the second member of the conventional core piece is about the same. Therefore, the core piece allows magnetic flux to pass through more easily than the conventional core piece.

[0030] (2) In one embodiment of the core piece, the powder compact has a relative density of 85% or more.

[0031] The core pieces have a high density, and therefore an axial gap type rotating electric machine having excellent magnetic properties such as saturation magnetic flux density can be constructed. Moreover, the core pieces have excellent mechanical properties such as strength.

[0032] (3) In one embodiment of the core piece, the soft magnetic particles are composed of pure iron or an iron-based alloy, and the iron-based alloy is an Fe-Si based alloy, an Fe-Al based alloy, or an Fe-Si-Al based alloy.

[0033] The core pieces have a high density and excellent dimensional accuracy because the material is relatively soft, and the soft magnetic particles are easily deformed during molding into a powder compact.

[0034] (4) In one embodiment of the core piece, the soft magnetic particles have an average particle size of 30 μm or more.

[0035] When the average particle size of the soft magnetic particles is 30 μm or more, the relative magnetic permeability is likely to be large. The core pieces including these soft magnetic particles have low loss. Therefore, the core pieces are easy to use in the construction of a low-loss axial gap type rotating electric machine.

[0036] (5) In one embodiment of the core piece, the second height accounts for 80% or more of the first height of the core piece, the first height is the length of the core piece along the axial direction of the stator core, and the second height is the length of the core piece along the axial direction of the stator core in a region excluding the second member.

[0037] In the above-mentioned core piece, the length of the region excluding the second member accounts for a large proportion of the length of the core piece. Therefore, when the length of the core piece is constant between the above-mentioned core piece and the conventional core piece, the above-mentioned core piece makes it easier to construct an axial gap type rotating electric machine having superior magnetic characteristics compared to the conventional core piece.

[0038] (6) In one embodiment of the core piece, the second member has an outer peripheral surface arranged on the outer peripheral side of the stator core, an inner peripheral surface arranged on the inner peripheral side of the stator core, and a first end face arranged on a first end side in the axial direction of the stator core, wherein corners between the outer peripheral surface and the first end face and corners between the inner peripheral surface and the first end face are chamfered, and the chamfer length of the corners is 0.1 mm or more and 0.5 mm or less.

[0039] When the chamfer length is within the above range, the corners are less likely to be damaged.

[0040] (7) One form of the core piece includes a plate-shaped third member provided on a second end side of the first member in the axial direction, the first member having a peripheral surface connected to the second member and the third member, the second member having a protruding portion protruding outward beyond the peripheral surface of the first member, and the third member having a protruding portion protruding outward beyond the peripheral surface of the first member, and the first member, the second member, and the third member being configured as an integrally molded pressed powder compact.

[0041] The above-mentioned core piece has excellent productivity for the following reasons.

[0042] Conventionally, a core piece having a first member, a second member, and a third member is formed by combining, for example, a powder compact in which the first member and the second member are integrally molded, and a third member formed separately from the powder compact. Alternatively, a conventional core piece is formed by combining, for example, a powder compact in which the first member and the third member are integrally molded, and a second member formed separately from the powder compact. That is, a conventional core piece needs to be formed by producing and combining at least two members. Therefore, the number of steps required for manufacturing a conventional core piece is large, and the manufacturing time is long. In addition, at least two dies are required for manufacturing a conventional core piece.

[0043] On the other hand, since the core piece is composed of a powder compact in which the first member, the second member, and the third member are integrally molded, there is no need to combine multiple members. Therefore, the core piece can be manufactured in fewer steps and in a shorter time than conventional core pieces. In addition, since the core piece is composed of a powder compact in which the first member, the second member, and the third member are integrally molded, it can be manufactured using a single mold. Therefore, the costs required for manufacturing and maintaining the mold can be reduced, and the core piece can be manufactured at low cost.

[0044] The above-mentioned core piece cannot be manufactured by a conventional manufacturing method along the same direction as the pressurizing direction and the removal direction of the core piece, because the second member and the third member each have a protrusion that gets caught on the inner peripheral surface of the die hole, preventing the core piece from being removed from the mold.

[0045] The above-mentioned core pieces can be manufactured by setting the pressing direction and the removal direction along the radial direction of the stator core, as described in detail below. The outer peripheral side and inner peripheral side surfaces of the core pieces are formed by the lower end surface of the upper punch and the upper end surface of the lower punch. The first direction side and second direction side surfaces of the circumferential direction of the stator core and the first end side and second end side surfaces of the axial direction of the stator core are formed by the inner peripheral surface of the die hole. In this case, even if each of the second member and the third member has a protruding portion, the protruding portion does not get caught on the inner peripheral surface of the die hole, so the core pieces can be removed from the mold.

[0046] (8) As one embodiment of the core piece of (7) above, each of the first member, the second member, and the third member has an outer peripheral surface arranged on the outer peripheral side of the stator core, an inner peripheral surface arranged on the inner peripheral side of the stator core, a first side surface arranged on a first direction side in the circumferential direction of the stator core and connected to the outer peripheral surface and the inner peripheral surface, and a second side surface arranged on a second direction side in the circumferential direction of the stator core and connected to the outer peripheral surface and the inner peripheral surface, and in each of the first member, the second member, and the third member, a length between the first side surface and the second side surface on the outer peripheral surface is the length between the first side surface and the second side surface of the first member, the second member, and the third member is longer than the length between the first side surface and the second side surface of the third member, and each of the first side surface and the second side surface of the first member, the second member, and the third member has a first parallel surface connected to the outer peripheral surface, a second parallel surface connected to the inner peripheral surface, and a first inclined surface connected to the first parallel surface and the second parallel surface, and in each of the first member, the second member, and the third member, the first parallel surface of the first side surface and the first parallel surface of the second side surface are parallel, the second parallel surface of the first side surface and the second parallel surface of the second side surface are parallel, and the first parallel surface of the first side surface and the second parallel surface of the first side surface are parallel.

[0047] The core pieces have a high relative density. The reason is as follows. The first parallel surface and the second parallel surface can be formed by straight portions along the pressure direction of the upper and lower punches in the die hole of the metal mold, as described in detail later. Therefore, sufficient pressure can be applied to the raw material powder constituting the core pieces.

[0048] The core piece has excellent productivity. The reason is as follows. As described in detail below, the first inclined surface can be formed by a tapered portion that intersects with the pressure direction of the upper punch and the lower punch in the die hole of the metal mold. The die hole has a straight portion, which prevents the upper punch and the lower punch from contacting the inner surface of the tapered portion. This extends the life of the metal mold, and increases the number of core pieces that can be produced with one metal mold.

[0049] (9) As one embodiment of the core piece of (8) above, in each of the first member, the second member, and the third member, the angle between the extension of the first parallel surface of the first side surface and the first inclined surface is 5° or more and 20° or less, and the angle between the extension of the first parallel surface of the second side surface and the first inclined surface is 5° or more and 20° or less.

[0050] Since the angle between the core pieces and the first member satisfies the above range, it is easy to wind a winding around the circumferential surface of the first member and to construct a stator. Since the angle between the core pieces and the second member satisfies the above range, it is easy to arrange the core pieces in an annular shape and to construct a stator core. Since the angle between the core pieces and the third member satisfies the above range, it is possible to suppress density variations within the core pieces.

[0051] (10) As one embodiment of the core piece of (8) or (9), each of the protruding portion of the second member and the protruding portion of the third member has a first protruding portion protruding toward a first direction in the circumferential direction and a second protruding portion protruding toward a second direction in the circumferential direction, a protruding amount of the first protruding portion of the second member is larger than a protruding amount of the first protruding portion of the third member, a protruding amount of the second protruding portion of the second member is larger than a protruding amount of the second protruding portion of the third member, and the first inclined surface of the first protruding portion of the second member is outwardly inclined from a first imaginary plane. the first inclined surface of the second protruding portion of the second member has a portion that protrudes outward beyond the second imaginary surface, the first imaginary surface is a plane that connects, on the first side surface of the first protruding portion of the second member, a connection point between the first parallel surface and the first inclined surface and a connection point between the second parallel surface and the inner circumferential surface, and the second imaginary surface is a plane that connects, on the second side surface of the second protruding portion of the second member, a connection point between the first parallel surface and the first inclined surface and a connection point between the second parallel surface and the inner circumferential surface.

[0052] The above core pieces make it easy to construct a stator core having a large magnetic path area for the following reasons.

[0053] The stator core is configured by arranging a plurality of core pieces in an annular shape. Some stator cores are configured by combining first core pieces and second core pieces that are adjacent to each other in the circumferential direction so as to be in contact with each other.

[0054] For example, in the case of a core piece in which the first side surface of the first protruding portion and the second side surface of the second protruding portion each have a first parallel surface, a second parallel surface, and a first inclined surface, and the first inclined surface does not have the above-mentioned protruding portion, the following occurs. When the core pieces are arranged in an annular shape, if the first side surface of the first protruding portion in the second member of the first core piece is brought into contact with the second side surface of the second protruding portion in the second member of the second core piece, the first corner of the first core piece comes into contact with the second corner of the second core piece. The first corner is a corner between the first side surface of the first protruding portion in the second member and the inner circumferential surface. The second corner is a corner between the second side surface of the second protruding portion in the second member and the inner circumferential surface. Therefore, the first side surface of the first protruding portion in the second member of the first core piece and the second side surface of the second protruding portion in the second member of the second core piece cannot be brought into sufficient contact with each other.

[0055] In contrast, the first side surface of the first protruding portion and the second side surface of the second protruding portion of the core piece each have a first parallel surface, a second parallel surface, and a first inclined surface, and the first inclined surface has a portion that protrudes beyond each of the first imaginary surface and the second imaginary surface. When the core pieces are arranged in a ring shape, even if the first side surface of the first protruding portion of the second member of the first core piece and the second side surface of the second protruding portion of the second member of the second core piece are brought into contact with each other, the first corner of the first core piece and the second corner of the second core piece can be prevented from coming into contact with each other. Therefore, the first side surface of the first protruding portion of the second member of the first core piece and the second side surface of the second protruding portion of the second member of the second core piece can be brought into sufficient contact with each other.

[0056] (11) As one embodiment of the core piece of (10) above, the first side surface of the first protrusion in the second member has one selected from the group consisting of at least one of a concave portion and a convex portion, a step, and a second inclined surface, and the second side surface of the second protrusion in the second member has one selected from the group consisting of at least one of a convex portion corresponding to the concave portion of the first side surface and a concave portion corresponding to the convex portion of the first side surface, a step corresponding to the step of the first side surface, and a second inclined surface corresponding to the second inclined surface of the first side surface.

[0057] The above core pieces make it easy to construct a stator core with a large magnetic path area. The reason is as follows: the first core pieces and the second core pieces adjacent to each other in the circumferential direction of the stator core can be fitted together at the steps or the projections and recesses, or can be brought into contact with each other at the second inclined surfaces. Therefore, the first core pieces and the second core pieces can be brought into sufficient contact with each other, and the contact area between the first core pieces and the second core pieces can be increased.

[0058] (12) In one embodiment of the core piece of (10) or (11) above, the third member has a first end face arranged on the opposite side to the side facing the second member, and the first end face is convex toward the opposite side.

[0059] The above core pieces can be used to construct an axial gap type rotating electric machine with low noise and vibration. The reasons are as follows. In an axial gap type rotating electric machine, a stator and a rotor are arranged facing each other. The stator is configured by arranging a coil in each first member of a stator core. The stator core is configured by arranging a plurality of core pieces in an annular shape. Since the first end faces of the core pieces are provided in a convex shape, sudden changes in the magnetic flux of the rotor magnet received by the core pieces are easily suppressed. Since sudden changes in magnetic flux are easily suppressed, cogging torque is easily reduced. Since the cogging torque is small, noise and vibration are less likely to increase.

[0060] (13) As one embodiment of the core piece of any one of (8) to (12) above, the outer peripheral surface of each of the first member, the second member, and the third member has a curved surface that is convex toward the outer peripheral side, and the inner peripheral surface of each of the first member, the second member, and the third member has a curved surface that is convex toward the inner peripheral side.

[0061] The core piece can suppress density variations within the core piece.

[0062] (14) As one embodiment of the core piece of any one of (8) to (13) above, a first seam between the protrusion of the second member and the peripheral surface of the first member and a second seam between the protrusion of the third member and the peripheral surface of the first member are rounded.

[0063] Since the first joint and the second joint of the core pieces are rounded, damage is unlikely to occur starting from each joint.

[0064] (15) In one embodiment of the core piece of (14) above, the bend radius of the first joint and the bend radius of the second joint are 0.2 mm or more and 4.0 mm or less.

[0065] The core pieces have a bending radius of 0.2 mm or more between the first joint and the second joint, which reduces the load on the die during manufacturing of the core pieces. The core pieces have a bending radius of 4.0 mm or less between the first joint and the second joint, which makes it easy to wind the coil when constructing the stator, and therefore makes it easy to increase the number of turns of the coil.

[0066] (16) As one embodiment of any one of the core pieces described above in (8) to (15), the second member and the third member each have a first end face arranged on the opposite side to the sides facing each other, and in each of the second member and the third member, a corner between the outer circumferential surface and the first end face, and a corner between the inner circumferential surface and the first end face are chamfered.

[0067] Since the corners of the core pieces are chamfered, the corners are less likely to be damaged.

[0068] (17) As one embodiment of the core piece of any one of (8) to (16) above, the total area of ​​the outer peripheral surface of each of the first member, the second member, and the third member is more than 1 time and not more than 4 times the total area of ​​the inner peripheral surface of each of the first member, the second member, and the third member.

[0069] The core pieces are easily arranged in an annular shape because the total area of ​​the outer peripheral faces is more than 1 times the total area of ​​the inner peripheral faces, making it easy to construct a stator core. The core pieces are easily manufactured because the total area of ​​the outer peripheral faces is 4 times or less the total area of ​​the inner peripheral faces. The ratio of the total area of ​​the inner peripheral faces is relatively high, so that when the core pieces are extracted from the die, the area for pushing out the core pieces with the lower punch is large. Therefore, it is easy to suppress damage to the core pieces when they are extracted from the die.

[0070] (18) As one embodiment of the core piece of any one of (8) to (17) above, among the regions obtained by dividing the core piece into three by a virtual plane along the second parallel surface of the first side surface and a virtual plane along the second parallel surface of the second side surface, the difference in relative density between a first region on a first direction side in the circumferential direction and a second region on a second direction side in the circumferential direction, and a third region between the first region and the second region is 5.0% or less.

[0071] The core pieces have small differences in relative density, so that the physical properties, such as magnetic properties, are substantially uniform within the core pieces.

[0072] (19) As one embodiment of the core pieces of (7) to (18) above, the difference in relative density between the first member, the second member, and the third member having the highest relative density and the member having the lowest relative density is 5% or less.

[0073] The core pieces have small differences in relative density, so that the physical properties, such as magnetic properties, are substantially uniform within the core pieces.

[0074] (20) A stator core according to one embodiment of the present disclosure is a stator core for an axial gap type rotating electric machine, and has a plurality of core pieces arranged in a ring shape, each of the plurality of core pieces being any one of the core pieces described above in (1) to (19).

[0075] The stator core includes the core pieces, so that an axial gap type rotating electric machine having excellent magnetic characteristics can be constructed.

[0076] (21) In one embodiment of the stator core, a variation in length between a face on a first end side and a face on a second end side in the axial direction of each of the plurality of core pieces is 0.1 mm or less.

[0077] The stator core has very small variation in length. Therefore, the stator core can be used to construct an axial gap type rotating electric machine with little noise and vibration. The reasons are as follows. In an axial gap type rotating electric machine, the stator and rotor are arranged facing each other as described above. The stator is configured by arranging a coil on the first member of each core piece of the stator core. Since the variation in the length of the stator core is small, the variation in the gap between the stator and rotor is small. Since the variation in the gap is small, torque ripple is small. Since the torque ripple is small, noise and vibration are less likely to increase.

[0078] (22) A stator according to one embodiment of the present disclosure is a stator for an axial gap type rotating electric machine, and includes a stator core as described in (20) or (21) above, and a coil arranged in each of the first members in the stator core.

[0079] The stator includes the stator core, so that an axial gap type rotating electric machine having excellent magnetic characteristics can be constructed.

[0080] (23) A rotating electric machine according to one aspect of the present disclosure is an axial gap type rotating electric machine including a rotor and a stator, the stator being the stator described above in (22).

[0081] The rotating electric machine includes the stator, and thus has excellent magnetic characteristics.

[0082] (24) As one embodiment of the above rotating electric machine, the proportion of the first magnetic resistance of the core piece in the magnetic resistance of the rotating electric machine is 2% or more, and the first magnetic resistance is the magnetic resistance of a region of the core piece excluding the second member.

[0083] As described above, the magnetic resistance of the first member of the core piece is smaller than that of the first member of the conventional core piece. Therefore, the higher the ratio of the first magnetic resistance, the more excellent the magnetic characteristics of the rotating electric machine including the core piece are compared to the rotating electric machine including the conventional core piece. The magnetic resistance of the axial gap type rotating electric machine will be described later.

[0084] (25) A method for manufacturing a core piece according to one embodiment of the present disclosure is a method for manufacturing a core piece arranged in a ring to construct a stator core of an axial gap type rotating electric machine, the method comprising the steps of filling a die with raw material powder containing a plurality of spherical soft magnetic particles, and compressing the raw material powder in the die to form a compact, the core piece comprising a columnar first member extending in the axial direction of the stator core, and a plate-shaped second member provided on a first end side of the first member in the axial direction of the stator core, and a direction for compressing the raw material powder is along the radial direction of the stator core.

[0085] The core piece manufacturing method according to the present disclosure can be manufactured by compressing the raw material powder in the radial direction of the stator core using spherical soft magnetic particles. Therefore, the core piece manufacturing method can manufacture a core piece that can be used to construct an axial gap type rotating electric machine with excellent magnetic properties.

[0086] Details of the embodiments of the present disclosure DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the embodiments of the present disclosure will be described below with reference to the drawings. In the drawings, the same reference numerals indicate the same objects.

[0087] First Embodiment A core piece 1 according to a first embodiment will be described with reference to Figs. 1 to 11. The core pieces 1 of this embodiment are arranged in an annular shape to form a stator core 7, as described later with reference to Fig. 16. The stator core 7 is used in an axial gap type rotating electric machine 9, as described later with reference to Figs. 18 and 19, although details will be described later. As shown in Fig. 1, the core piece 1 of this embodiment includes a columnar first member 10 and a plate-shaped second member 20. The first member 10 extends in the axial direction of the stator core 7. The second member 20 is provided on a first end side of the first member 10 in the axial direction. One of the features of the core piece 1 of this embodiment is that it satisfies all of the following configurations (a) to (c).

[0088] (a) A first member 10 and a second member 20 are formed as a powder compact by being compressed in a specific direction and integrally molded. (b) In the first cross section of the first member 10 shown in FIG. 7, the first average aspect ratio of the soft magnetic particles 40 shown in FIG. 8 satisfies a specific range. (c) In the second cross section of the second member 20 shown in FIG. 5, the second average aspect ratio of the soft magnetic particles 40 shown in FIG. 9 satisfies a specific range. The first member 10 and the second member 20 being integrally molded means that the first member 10 and the second member 20 are integrated by molding, without being mechanically connected using screws or the like, or bonded with an adhesive or the like.

[0089] In this embodiment, the core piece 1 includes a plate-shaped third member 30 in addition to the first member 10 and the second member 20. The third member 30 is provided on the second end side of the first member 10 in the axial direction. The core piece 1 is composed of a powder compact in which the first member 10, the second member 20, and the third member 30 are integrally molded. As described above, the first member 10, the second member 20, and the third member 30 are integrally molded by molding without mechanical connection using screws or adhesion using adhesives. Note that, as will be described later with reference to FIG. 15, the core piece 1 may not include the third member 30 as long as it includes the first member 10 and the second member 20.

[0090] The direction along the radial direction of the stator core 7 in the core piece 1 is defined as the X-axis direction. The direction along the axial direction of the stator core 7 in the core piece 1 is taken as the Z-axis direction. The direction perpendicular to both the X-axis direction and the Z-axis direction of the core piece 1 is defined as the Y-axis direction. In the X-axis direction, the inner circumferential side of the stator core 7 in the core piece 1 is defined as an X1 direction, and the outer circumferential side of the stator core 7 is defined as an X2 direction. In the Z-axis direction, the second member 20 side relative to the first member 10 in the core piece 1 is defined as a Z1 direction, and the third member 30 side relative to the first member 10 is defined as a Z2 direction. The Z1 direction is the first end side of the first member 10. The Z2 direction is the second end side of the first member 10. In the Y-axis direction, a first direction side of stator core 7 in core piece 1 is defined as a Y1 direction, and a second direction side of stator core 7 is defined as a Y2 direction.

[0091] [First member] The first member 10 is a columnar member extending in the Z-axis direction. The first member 10 constitutes teeth in either case where the core pieces 1 are used to construct a stator core 7 provided in a double stator / single rotor configuration of an axial gap type rotating electric machine 9, or where the core pieces 1 are used to construct a stator core 7 in a single stator / double rotor configuration of an axial gap type rotating electric machine 9. The axial gap type rotating electric machine 9 in a double stator / single rotor configuration is assembled so that one rotor 90 is sandwiched between two stators 8, as shown in FIG. 18. The axial gap type rotating electric machine 9 in a single stator / double rotor configuration is assembled so that one stator 8 is sandwiched between two rotors 90, as shown in FIG. 19. Hereinafter, for convenience of explanation, the double stator / single rotor may be referred to as DS / SR, and the single stator / double rotor may be referred to as SS / DR.

[0092] As shown in FIG. 3, the ratio of the second height H10 to the first height H1 of the core piece 1 is, for example, 80% or more. Both the first height H1 and the second height H10 are lengths in the Z-axis direction. The first height H1 is the length of the entire core piece 1, that is, in this embodiment, the length between the first end face 26 of the second member 20 and the first end face 36 of the third member 30, which will be described later. The second height H10 is the length of the region excluding the second member, that is, in this embodiment, the total height of the first member 10 and the third member 30. Specifically, the second height H10 is the length between the second end face 27 of the second member 20 and the first end face 36 of the third member 30, which will be described later. The larger the ratio, the easier it is to obtain the effect of the core piece 1 satisfying the above configuration (b). This effect will be described later. The ratio can further be 82% or more, and particularly 85% or more. The upper limit of the ratio can be, for example, 95%. That is, the above ratio is 80% or more and 95% or less, further 82% or more and 93% or less, and particularly 85% or more and 90% or less.

[0093] The shape of the first member 10 may be, for example, a rectangular column or a cylindrical column. The rectangular column may be a quadrangular column whose cross section cut along a plane perpendicular to the Z-axis direction is a square. The quadrangular column may be a trapezoidal column whose cross section is a trapezoid. The cross section may be uniform in the Z-axis direction. The term "trapezoid" refers not only to a geometric trapezoid, but also to a shape having rounded corners as in this example, and includes a range that is substantially considered to be a trapezoid. The term "trapezoid" refers to a trapezoid whose legs are the same length, such as an isosceles trapezoid, as well as a trapezoid whose legs are different lengths, such as a right-angled trapezoid. This point is the same for the second member 20 and the third member 30 described later.

[0094] As shown in Figs. 1 and 4, the shape of the first member 10 in this embodiment is a trapezoidal columnar shape in which the cross-sectional shape is a trapezoid. The cross-sectional shape has a longer side on the X2 direction side and a shorter side on the X1 direction side. The cross-sectional shape of the first member 10 is uniform in the Z-axis direction. If the shape of the first member 10 is a trapezoidal columnar shape, it is easy to ensure a large cross-sectional area. In addition, it is easy to reduce the dead space of the core pieces 1, and it is easy to construct a stator 8 with a high space factor.

[0095] As shown in FIG. 1 and FIG. 3, the first member 10 has a peripheral surface 11 connected to the second member 20 and the third member 30. As shown in FIG. 4, the peripheral surface 11 of the first member 10 shown in FIG. 1 and FIG. 3 has an outer peripheral surface 12, an inner peripheral surface 13, a first side surface 14a, and a second side surface 14b. The outer peripheral surface 12 is located on the X2 direction side. The inner peripheral surface 13 is located on the X1 direction side. The first side surface 14a and the second side surface 14b are located on the sides that are separated from each other in the circumferential direction of the stator core 7 in the core piece 1. That is, the first side surface 14a is located on the first direction side in the circumferential direction of the stator core 7 in the core piece 1. The second side surface 14b is located on the second direction side in the circumferential direction of the stator core 7 in the core piece 1. The positional relationship between the outer peripheral surface 12, the inner peripheral surface 13, the first side surface 14a, and the second side surface 14b is the same in the second member 20 and the third member 30 described later.

[0096] The outer peripheral surface 12 is connected to the outer peripheral edge of the first side surface 14a and the outer peripheral edge of the second side surface 14b. The inner peripheral surface 13 is connected to the inner peripheral edge of the first side surface 14a and the inner peripheral edge of the second side surface 14b. That is, the first side surface 14a and the second side surface 14b are connected to the outer peripheral surface 12 and the inner peripheral surface 13.

[0097] The length between the first side surface 14a and the second side surface 14b on the outer peripheral surface 12 is longer than the length between the first side surface 14a and the second side surface 14b on the inner peripheral surface 13. In this embodiment, the outer peripheral surface 12 has a curved surface that is convex toward the X2 direction side. The outer peripheral surface 12 may be configured as a flat surface. In this embodiment, the inner peripheral surface 13 has a curved surface that is convex toward the X1 direction side. The inner peripheral surface 13 may have a curved surface that is convex toward the X2 direction side, or may be configured as a flat surface. The bending radii of the outer peripheral surface 12 and the inner peripheral surface 13 may be the same or different from each other.

[0098] Each of the first side surface 14a and the second side surface 14b has a first parallel surface 141, a second parallel surface 142, and a first inclined surface 143. The first parallel surfaces 141 of the first side surface 14a and the second side surface 14b are parallel to each other. The second parallel surfaces 142 of the first side surface 14a and the second side surface 14b are parallel to each other. The first parallel surface 141 of the first side surface 14a and the second parallel surface 142 of the first side surface 14a are parallel to each other. The first parallel surface 141 and the second parallel surface 142 are parallel to the X-axis direction of the core piece 1. The X-axis direction refers to a direction along a straight line that passes through the center of the stator core 7 and divides the core piece 1 into two equal parts in the circumferential direction of the stator core 7. The first parallel surface 141 is continuous with the outer peripheral surface 12. The second parallel surface 142 is continuous with the inner peripheral surface 13. The first inclined surface 143 is continuous with the first parallel surface 141 and the second parallel surface 142.

[0099] The length of the first parallel surface 141 and the second parallel surface 142 along the X-axis direction depends on the size of the core piece 1, and is preferably, for example, 0.3 mm or more and 25 mm or less. If it is equal to or more than the lower limit, damage to the die 5 caused by contact between the lower punch 55 and the die 50, which will be described later with reference to FIG. 11, can be suppressed. Although the manufacturing method of the core piece 1 will be described later, if it is equal to or more than the lower limit, sufficient pressure can be applied to the raw material powder constituting the core piece 1. If it is equal to or less than the upper limit, the cross-sectional area of ​​the first member 10 can be increased, so that the torque in the axial gap type rotating electric machine 9 can be improved and iron loss can be suppressed. The length of the first parallel surface 141 and the second parallel surface 142 along the X-axis direction is further preferably equal to or more than 0.4 mm and 20 mm or less, and particularly preferably equal to or more than 0.5 mm and 15 mm or less. The above-mentioned preferred ranges of the lengths along the X-axis direction of the first parallel surface 141 and the second parallel surface 142 on each of the first side surface 14a and the second side surface 14b of the first member 10 are also the same for the first parallel surface 241 and the second parallel surface 242 on each of the first side surface 24a and the second side surface 24b of the second member 20, and the first parallel surface 341 and the second parallel surface 342 on each of the first side surface 34a and the second side surface 34b of the third member 30, which will be described later.

[0100] As shown in FIG. 4, the first inclination angle θ11 and the second inclination angle θ12 of the first inclined surface 143 are preferably, for example, 5° or more and 20° or less. If the first inclination angle θ11 and the second inclination angle θ12 are 5° or more and 20° or less, it is easy to wind a winding, which will be described later, around the circumferential surface 11 of the first member 10, so that the stator core 7 shown in FIG. 16 is easily constructed. The first inclination angle θ11 and the second inclination angle θ12 are further preferably 5.5° or more and 18° or less, and particularly preferably 6° or more and 16° or less. The first inclination angle θ11 and the second inclination angle θ12 are preferably the same angle, but may be different. The first inclination angle θ1 refers to the angle between the extension surface E11 of the first parallel surface 141 on the first side surface 14a and the first inclined surface 143. The second inclination angle θ12 refers to the angle between the extension surface E12 of the first parallel surface 141 on the second side surface 14b and the first inclined surface 143.

[0101] [Second component] 1 and 3, the second member 20 is a plate-like member provided on the first end side in the Z-axis direction of the first member 10. When the core pieces 1 are used to construct a stator core 7 provided in an axial gap type rotating electric machine 9 of a DS / SR configuration, the second member 20 forms a yoke. When the core pieces 1 are used to construct a stator core 7 provided in an axial gap type rotating electric machine 9 of a SS / DR configuration, the second member 20 forms a flange portion.

[0102] In this embodiment, the second member 20 has a trapezoidal plate shape. The trapezoidal plate shape is a trapezoidal cross section obtained by cutting the second member 20 along a plane perpendicular to the Z-axis direction. The cross section is uniform in the Z-axis direction. Note that the shape of the second member 20 may be a rectangular plate when the core pieces 1 are used to construct a stator core 7 provided in an axial gap type rotating electric machine 9 of SS / DR type.

[0103] As shown in FIG. 1 to FIG. 3, the second member 20 has a protruding portion 21. The protruding portion 21 protrudes outward from the peripheral surface 11 of the first member 10. The protruding portion 21 may protrude outward from the peripheral surface 11 of the first member 10 in a part of the peripheral surface 11 of the first member 10, or may protrude outward from the peripheral surface 11 of the first member 10 over the entire circumference of the first member 10 in the circumferential direction. In this embodiment, the protruding portion 21 has a first protruding portion 211 and a second protruding portion 212. The first protruding portion 211 protrudes toward a first direction side in the circumferential direction of the stator core 7. The second protruding portion 212 protrudes toward a second direction side in the circumferential direction of the stator core 7. Note that the protruding portion 21 may not have the first protruding portion 211 and the second protruding portion 212, and may have a portion protruding toward the X1 direction side and a portion protruding toward the X2 direction side. The protruding portion 21 may have a portion protruding in the X1 direction and a portion protruding in the X2 direction, in addition to the first protruding portion 211 and the second protruding portion 212. In this case, the protruding portion 21 is provided in an annular shape.

[0104] The protruding length of the first protruding portion 211 and the second protruding portion 212 of the second member 20 is longer than the protruding length of the first protruding portion 211 and the second protruding portion 212 of the third member 30 described later when the core piece 1 is used to construct a stator core 7 provided in an axial gap type rotating electric machine 9 of a DS / SR type. The protruding length of the first protruding portion 211 and the second protruding portion 212 of the second member 20 may be the same as the protruding length of the first protruding portion 211 and the second protruding portion 212 of the third member 30 when the core piece 1 is used to construct a stator core 7 provided in an axial gap type rotating electric machine 9 of a SS / DR type. The protruding length refers to the length along a direction perpendicular to the circumferential surface 11 of the first member 10. When the circumferential surface 11 has a curved surface, the protruding length refers to the length along the normal direction of the curved surface.

[0105] As shown in Figs. 3 and 5, the second member 20 has an outer peripheral surface 22, an inner peripheral surface 23, a first side surface 24a, a second side surface 24b, a first end surface 26, and a second end surface 27. The positional relationship between the outer peripheral surface 22, the inner peripheral surface 23, the first side surface 24a, and the second side surface 24b is the same as the positional relationship between the respective surfaces in the first member 10, as described above. The first end surface 26 and the second end surface 27 are disposed in positions facing each other. The first end surface 26 is located on the Z1 direction side. The first end surface 26 is located on the Z1 direction side of the second member 20. The second end surface 27 is located on the Z2 direction side. The second end surface 27 is located on the first member 10 side of the second member 20. The positional relationship between the first end surface 26 and the second end surface 27 is the same in the third member 30 described later.

[0106] The outer peripheral surface 22 is continuous with the outer peripheral edge of the first side surface 24a, the outer peripheral edge of the second side surface 24b, the outer peripheral edge of the first end surface 26, and the outer peripheral edge of the second end surface 27. The outer peripheral surface 22 of the second member 20 is continuous with the outer peripheral surface 12 of the first member 10. The inner peripheral surface 23 is continuous with the inner peripheral edge of the first side surface 24a, the inner peripheral edge of the second side surface 24b, the inner peripheral edge of the first end surface 26, and the inner peripheral edge of the second end surface 27. The inner peripheral surface 23 of the second member 20 is continuous with the inner peripheral surface 13 of the first member 10. The first side surface 24a and the second side surface 24b are continuous with the outer peripheral surface 22 and the inner peripheral surface 23. The first end surface 26 is continuous with the outer peripheral surface 22, the first side surface 24a, the second side surface 24b, and the inner peripheral surface 23. The second end surface 27 is connected to the outer peripheral surface 22, the first side surface 24a, the second side surface 24b, the inner peripheral surface 23, and the peripheral surface 11 of the first member 10.

[0107] The length between the first side surface 24a and the second side surface 24b at the outer peripheral surface 22 is longer than the length between the first side surface 24a and the second side surface 24b at the inner peripheral surface 23. The length between the first side surface 24a and the second side surface 24b at the outer peripheral surface 22 of the second member 20 is longer than the length between the first side surface 14a and the second side surface 14b at the peripheral surface 11 of the first member 10. The length between the first side surface 24a and the second side surface 24b at the inner peripheral surface 23 of the second member 20 is the same as the length between the first side surface 14a and the second side surface 14b at the inner peripheral surface 13 of the first member 10.

[0108] In this embodiment, the outer peripheral surface 22 has a curved surface that is convex toward the X2 direction side. The outer peripheral surface 22 may be configured as a flat surface. In this embodiment, the inner peripheral surface 23 has a curved surface that is convex toward the X1 direction side. The inner peripheral surface 23 may have a curved surface that is convex toward the X2 direction side, or may be configured as a flat surface. The bending radii of the outer peripheral surface 22 and the inner peripheral surface 23 may be the same or different from each other.

[0109] Each of the first side surface 24a and the second side surface 24b has a first parallel surface 241, a second parallel surface 242, and a first inclined surface 243. The first parallel surfaces 241 of the first side surface 24a and the second side surface 24b are parallel to each other. The second parallel surfaces 242 of the first side surface 24a and the second side surface 24b are parallel to each other. The first parallel surface 241 of the first side surface 24a and the second parallel surface 242 of the first side surface 24a are parallel to each other. The first parallel surface 241 and the second parallel surface 242 are parallel to the X-axis direction of the core piece 1. The first parallel surface 241 is continuous with the outer peripheral surface 22. The second parallel surface 242 is continuous with the inner peripheral surface 23. The first inclined surface 243 is continuous with the first parallel surface 241 and the second parallel surface 242.

[0110] As shown in FIG. 5, the first inclination angle θ21 and the second inclination angle θ22 of the first inclined surface 243 are preferably, for example, 5° or more and 20° or less. If the first inclination angle θ21 and the second inclination angle θ22 are 5° or more and 20° or less, the core pieces 1 are easily arranged in an annular shape, and the stator core 7 is easily constructed. The first inclination angle θ21 and the second inclination angle θ22 are more preferably 5.5° or more and 18° or less, and particularly preferably 6° or more and 16° or less. The first inclination angle θ21 and the second inclination angle θ22 are preferably the same angle, but may be different. The first inclination angle θ21 refers to the angle between the extension surface E21 of the first parallel surface 241 on the first side surface 24a and the first inclined surface 243. The second inclination angle θ22 refers to the angle between the extension surface E22 of the first parallel surface 241 on the second side surface 24b and the first inclined surface 243.

[0111] When constructing a stator core 7 in an axial gap type rotating electric machine 9 in which the core pieces 1 are of the DS / SR configuration, the first core piece 1 and the second core piece 1 adjacent to each other in the circumferential direction of the stator core 7 are in contact with each other at the first side surface 24a of the second member 20 of the first core piece 1 and the second side surface 24b of the second member 20 of the second core piece 1. In this case, the first inclined surface 243 of the first side surface 24a preferably has a portion 244 that protrudes outward from the first imaginary plane V21. The first inclined surface 243 of the second side surface 24b preferably has a portion 244 that protrudes outward from the second imaginary plane V22.

[0112] The first imaginary plane V21 is a plane that connects the first connection point and the second connection point on the first side surface 24a of the first protruding portion 211. The first connection point on the first side surface 24a is a connection point between the first parallel surface 241 and the first inclined surface 243 of the first side surface 24a. The second connection point on the first side surface 24a is a connection point between the second parallel surface 242 of the first side surface 24a and the inner circumferential surface 23. The second imaginary plane V22 is a plane that connects the first connection point and the second connection point on the second side surface 24b of the second protruding portion 212. The first connection point on the second side surface 24b is a connection point between the first parallel surface 241 and the first inclined surface 243 of the second side surface 24b. The second connection point on the second side surface 24b is a connection point between the second parallel surface 242 of the second side surface 24b and the inner circumferential surface 23. The first imaginary plane V21 and the second imaginary plane V22 are indicated by two-dot chain lines extending in a diagonal direction relative to the plane of the drawing in FIG.

[0113] The magnetic path area of ​​the stator core 7 is easily increased by the first inclined surface 243 of each of the first side surface 24a and the second side surface 24b having the protruding portion 244. The reason is as follows. For example, in the case of a core piece in which each of the first side surface 24a and the second side surface 24b has the first parallel surface 241, the second parallel surface 242, and the first inclined surface 243 and the first inclined surface 243 does not have the protruding portion 244, the following occurs. When the core pieces are arranged in an annular shape, if the first side surface 24a of the first core piece and the second side surface 24b of the second core piece adjacent to each other in the circumferential direction of the stator core 7 are brought into contact with each other, the first corner of the first core piece and the second corner of the second core piece come into contact with each other. The first corner is a corner between the first side surface 24a and the inner circumferential surface 23. The second corner is a corner between the second side surface 24b and the inner circumferential surface 23. Therefore, the first side surface 24a of the first core piece 1 and the second side surface 24b of the second core piece cannot be in sufficient contact with each other. That is, the contact area between the first side surface 24a of the first core piece 1 and the second side surface 24b of the second core piece is reduced.

[0114] In contrast, the first side surface 24a of the core piece 1 has a first parallel surface 241, a second parallel surface 242, and a first inclined surface 243, and the first inclined surface 243 has a portion 244 that protrudes from the first imaginary surface V21. The second side surface 24b of the core piece 1 has a first parallel surface 241, a second parallel surface 242, and a first inclined surface 243, and the first inclined surface 243 has a portion 244 that protrudes from the second imaginary surface V22. When the core pieces 1 are arranged in an annular shape, even if the first side surface 24a of the first core piece 1 and the second side surface 24b of the second core piece 1 are brought into contact with each other, the first corner of the first core piece 1 and the second corner of the second core piece 1 can be prevented from coming into contact with each other. Therefore, the first side surface 24a of the first core piece 1 and the second side surface 24b of the second core piece 1 can be brought into sufficient contact with each other. That is, the contact area between the first side surface 24a of the first core piece 1 and the second side surface 24b of the second core piece 1 increases.

[0115] When constructing a stator core 7 in an axial gap type rotating electric machine 9 in which the core pieces 1 are of the DS / SR type, as described above, the first core pieces 1 and the second core pieces 1 adjacent to each other in the circumferential direction of the stator core 7 are in contact with each other at the first side surface 24a of the second member 20 of the first core piece 1 and the second side surface 24b of the second member 20 of the second core piece 1. In this case, it is preferable that the first side surface 24a and the second side surface 24b of the core pieces 1 have a step 240 that can be fitted into each other, as shown in FIG. 3. In this case, the magnetic path area of ​​the stator core 7 is easily increased. The first core pieces 1 and the second core pieces 1 adjacent to each other in the circumferential direction of the stator core 7 are fitted into each other at the step 240 of the first side surface 24a of the first protruding portion 211 of the second member 20 of the first core piece 1 and the step 240 of the second side surface 24b of the second protruding portion 212 of the second member 20 of the second core piece 1. Therefore, the first core laminations 1 and the second core laminations 1 can be brought into sufficient contact with each other, so that the contact area between the core laminations 1 adjacent to each other in the circumferential direction of the stator core 7 can be increased. The step 240 of the first side surface 24a is provided on the first end face 26 side. The step 240 of the first side surface 24a is configured to become farther away from the first side surface 14a of the first member 10 from the first end face 26 toward the second end face 27. On the other hand, the step 240 of the second side surface 24b is provided on the second end face 27 side. The step 240 of the second side surface 24b is configured to become farther away from the second side surface 14b of the first member 10 from the second end face 27 toward the first end face 26.

[0116] Although not shown, the first side surface 24a of the core piece 1 may have at least one of a recess and a protrusion, instead of a step. The second side surface 24b may have at least one of a protrusion corresponding to the recess of the first side surface 24a and a recess corresponding to the protrusion of the first side surface 24a. That is, both the first side surface 24a and the second side surface 24b may have unevenness. In addition, either one of the first side surface 24a and the second side surface 24b may have only a recess, and the other side surface may have only a protrusion. The number and shape of the recesses and protrusions are not particularly limited.

[0117] Although not shown, each of the first side surface 24a and the second side surface 24b of the core piece 1 may have a second inclined surface in contact with each other, instead of a step or unevenness. For example, the second inclined surface of the first side surface 24a may be inclined outward from the first end surface 26 toward the second end surface 27. And, the second inclined surface of the second side surface 24b may be inclined outward from the second end surface 27 toward the first end surface 26.

[0118] When constructing a stator core 7 in an axial gap type rotating electric machine 9 having the core pieces 1 in the SS / DR configuration, the core pieces 1 are arranged in an annular shape without contacting each other. In this case, each of the first side surface 24a and the second side surface 24b does not need to have any of the step 240, the recessed portion, the protruding portion, and the second inclined surface that can fit into each other.

[0119] A corner between the first side surface 24a and the first end surface 26 and a corner between the first side surface 24a and the second end surface 27 are rounded. A corner between the second side surface 24b and the first end surface 26 and a corner between the second side surface 24b and the second end surface 27 are rounded.

[0120] When the core pieces 1 are used to construct a stator core 7 for an axial gap type rotating electric machine 9 in a DS / SR configuration, the first end surface 26 may be configured as a flat surface. When the core pieces 1 are used to construct a stator core 7 for an axial gap type rotating electric machine 9 in a SS / DR configuration, the first end surface 26 may be configured as a flat surface or may be configured as a convex surface facing the Z1 direction. Such a core piece 1 can construct an axial gap type rotating electric machine 9 with low noise and vibration. The reason is as follows. In the axial gap type rotating electric machine 9 in the SS / DR configuration, as shown in FIG. 19, a stator 8 and a rotor 90 are disposed facing each other. As shown in FIG. 17, the stator 8 includes a stator core 7 and a coil 80. As shown in FIG. 16 and FIG. 17, the stator core 7 is configured by arranging a plurality of core pieces 1 in an annular shape. As shown in FIG. 17, the coil 80 is disposed in the first member 10 of each core piece 1. If the first end face 26 of the second member 20 of the core piece 1 is provided in a convex shape, in the axial gap type rotating electric machine 9 shown in Fig. 19, a sudden change in the magnetic flux of the magnet 95 of the rotor 90 received by the core piece 1 is easily suppressed. Therefore, the cogging torque is easily reduced. Since the cogging torque is small, noise and vibration are unlikely to increase.

[0121] It is preferable that corners 28 between the first end face 26 and the inner peripheral surface 23 and corners 28 between the first end face 26 and the outer peripheral surface 22 are chamfered. These corners 28 are less likely to be damaged by being chamfered. These chamfers may be C-chamfered or R-chamfered.

[0122] The chamfer length of the corner 28 is preferably, for example, 0.1 mm or more and 0.5 mm or less. In the case of C-chamfering, the chamfer length refers to the length of the shorter side of two sides excluding the hypotenuse in a right triangle with the corner 28 as the hypotenuse. In the case of R-chamfering, the chamfer length refers to the length of the shorter side of two sides excluding the hypotenuse in a right triangle with the hypotenuse being a line segment connecting the inflection points between the curved surface of the corner 28 and each face connected to the curved surface. When the chamfer length is in the above range, the corner 28 is less likely to be damaged. The chamfer length is more preferably 0.15 mm or more and 0.45 mm or less, and particularly preferably 0.2 mm or more and 0.4 mm or less.

[0123] [Third member] 1 and 3, the third member 30 is a plate-like member provided on the second end side in the Z-axis direction of the first member 10. The third member 30 forms a flange portion in either case where the core pieces 1 are used to construct a stator core 7 provided in an axial gap type rotating electric machine 9 of a DS / SR configuration or a stator core 7 provided in an axial gap type rotating electric machine 9 of a SS / DR configuration.

[0124] The shape of the third member 30 in this embodiment is a trapezoidal plate shape. The trapezoidal plate shape is a trapezoidal cross-sectional shape obtained by cutting the third member 30 along a plane perpendicular to the Z-axis direction. The cross-section is uniform in the Z-axis direction. The shape of the third member 30 may be a rectangular plate shape. For example, the core piece 1 may have a first member 10 in the shape of a trapezoidal column, and at least one of the second member 20 and the third member 30 in the shape of a rectangular plate.

[0125] As shown in FIG. 1 to FIG. 3, the third member 30 has a protruding portion 31. The protruding portion 31 protrudes outward from the peripheral surface 11 of the first member 10. The protruding portion 31 may protrude outward from the peripheral surface 11 of the first member 10 in a part of the peripheral surface 11 of the first member 10, or may protrude outward from the peripheral surface 11 of the first member 10 over the entire circumference of the first member 10 in the circumferential direction. In this embodiment, the protruding portion 31 has a first protruding portion 311 and a second protruding portion 312. The first protruding portion 311 protrudes toward a first direction side in the circumferential direction of the stator core 7. The second protruding portion 312 protrudes toward a second direction side in the circumferential direction of the stator core 7. Note that the protruding portion 31 may not have the first protruding portion 311 and the second protruding portion 312, and may have at least one of a portion protruding toward the X1 direction side and a portion protruding toward the X2 direction side. The protruding portion 31 may have a portion protruding in the X1 direction and a portion protruding in the X2 direction, in addition to the first protruding portion 311 and the second protruding portion 312. In this case, the protruding portion 31 is provided in an annular shape.

[0126] As described above, when the core piece 1 is used to construct a stator core 7 for an axial gap type rotating electric machine 9 of a DS / SR configuration, the protruding length of the first protruding portion 311 and the second protruding portion 312 of the third member 30 is shorter than the protruding length of the first protruding portion 311 and the second protruding portion 312 of the second member 20. As described above, when the core piece 1 is used to construct a stator core 7 for an axial gap type rotating electric machine 9 of a SS / DR configuration, the protruding length of the first protruding portion 311 and the second protruding portion 312 of the third member 30 may be set to the same as the protruding length of the first protruding portion 211 and the second protruding portion 212 of the second member 20.

[0127] 6, the third member 30 has an outer peripheral surface 32, an inner peripheral surface 33, a first side surface 34a, a second side surface 34b, a first end surface 36, and a second end surface 37. As described above, the positional relationship between the outer peripheral surface 32, the inner peripheral surface 33, the first side surface 34a, and the second side surface 34b is similar to the positional relationship between the respective surfaces in the first member 10. As described above, the positional relationship between the first end surface 36 and the second end surface 37 is similar to the positional relationship between the respective surfaces in the second member 20.

[0128] The outer peripheral surface 32 is connected to the outer peripheral edge of the first side surface 34a, the outer peripheral edge of the second side surface 34b, the outer peripheral edge of the first end surface 36, and the outer peripheral edge of the second end surface 37. The outer peripheral surface 32 of the third member 30 is connected to the outer peripheral surface 12 of the first member 10. The inner peripheral surface 33 is connected to the inner peripheral edge of the first side surface 34a, the inner peripheral edge of the second side surface 34b, the inner peripheral edge of the first end surface 36, and the inner peripheral edge of the second end surface 37. The inner peripheral surface 33 of the third member 30 is connected to the inner peripheral surface 13 of the first member 10. The first side surface 34a and the second side surface 34b are connected to the outer peripheral surface 32 and the inner peripheral surface 33. The first end surface 36 is connected to the outer peripheral surface 32, the first side surface 34a, the second side surface 34b, and the inner peripheral surface 33. The second end surface 37 is connected to the outer circumferential surface 32, the first side surface 34a, the second side surface 34b, the inner circumferential surface 33, and the circumferential surface 11 of the first member 10.

[0129] The length between the first side surface 34a and the second side surface 34b on the outer peripheral surface 32 is longer than the length between the first side surface 34a and the second side surface 34b on the inner peripheral surface 33. The length between the first side surface 34a and the second side surface 34b on the outer peripheral surface 32 of the third member 30 is longer than the length between the first side surface 14a and the second side surface 14b on the outer peripheral surface 12 of the first member 10. The length between the first side surface 34a and the second side surface 34b on the outer peripheral surface 32 of the third member 30 is shorter than the length between the first side surface 24a and the second side surface 24b on the outer peripheral surface 22 of the second member 20. The length between the first side surface 34a and the second side surface 34b on the inner peripheral surface 33 of the third member 30 is the same as the length between the first side surface 14a and the second side surface 14b on the inner peripheral surface 13 of the first member 10. That is, the length between the first side surface 14a and the second side surface 14b on the inner surface 13 of the first member 10, the length between the first side surface 24a and the second side surface 24b on the inner surface 23 of the second member 20, and the length between the first side surface 34a and the second side surface 34b on the inner surface 33 of the third member 30 are identical to each other.

[0130] In this embodiment, the outer peripheral surface 32 has a curved surface that is convex toward the X2 direction side. The outer peripheral surface 32 may be configured as a flat surface. In this embodiment, the inner peripheral surface 33 has a curved surface that is convex toward the X1 direction side. The inner peripheral surface 33 may have a curved surface that is convex toward the X2 direction side, or may be configured as a flat surface. The bending radii of the outer peripheral surface 32 and the inner peripheral surface 33 may be the same or different from each other.

[0131] The bending radii of at least two of the outer peripheral surfaces 12, 22, and 32 may be the same. Of course, the bending radii of the outer peripheral surfaces 12, 22, and 32 may all be the same. The bending radii of the outer peripheral surfaces 12, 22, and 32 may all be different. Of the inner peripheral surfaces 13, 23, and 33, the bending radii of at least two of the inner peripheral surfaces may be the same. Of course, the bending radii of the inner peripheral surfaces 13, 23, and 33 may all be the same. The bending radii of the inner peripheral surfaces 13, 23, and 33 may all be different.

[0132] Each of the first side surface 34a and the second side surface 34b has a first parallel surface 341, a second parallel surface 342, and a first inclined surface 343. The first parallel surfaces 341 of the first side surface 34a and the second side surface 34b are parallel to each other. The second parallel surfaces 342 of the first side surface 34a and the second side surface 34b are parallel to each other. The first parallel surface 341 of the first side surface 34a and the second parallel surface 342 of the first side surface 34a are parallel to each other. The first parallel surface 341 and the second parallel surface 342 are parallel to the X-axis direction of the core piece 1. The first parallel surface 341 is continuous with the outer peripheral surface 32. The second parallel surface 342 is continuous with the inner peripheral surface 33. The first inclined surface 343 is continuous with the first parallel surface 341 and the second parallel surface 342.

[0133] As shown in FIG. 6, the first inclination angle θ31 and the second inclination angle θ32 of the first inclined surface 343 are preferably, for example, 5° or more and 20° or less. If the first inclination angle θ31 and the second inclination angle θ32 are 5° or more and 20° or less, the variation in density of the core piece 1 can be suppressed. The first inclination angle θ31 and the second inclination angle θ32 are more preferably 5.5° or more and 18° or less, and particularly preferably 6° or more and 16° or less. The first inclination angle θ31 and the second inclination angle θ32 are preferably the same angle, but may be different. The first inclination angle θ31 refers to the angle between the extension surface E31 of the first parallel surface 341 on the first side surface 34a and the first inclined surface 343. The second inclination angle θ32 refers to the angle between the extension surface E32 of the first parallel surface 341 on the second side surface 34b and the first inclined surface 343.

[0134] At least two of the first inclination angles θ11, the first inclination angle θ21, and the first inclination angle θ31 may be the same. At least two of the second inclination angles θ12, the second inclination angle θ22, and the second inclination angle θ32 may be the same. Of course, the first inclination angle θ11, the first inclination angle θ21, and the first inclination angle θ31 may all be the same. The second inclination angle θ12, the second inclination angle θ22, and the second inclination angle θ32 may all be the same. Note that the first inclination angle θ11, the first inclination angle θ21, and the first inclination angle θ31 may all be different. The second inclination angle θ12, the second inclination angle θ22, and the second inclination angle θ32 may all be different.

[0135] A corner between the first side surface 34a and the first end surface 36 and a corner between the first side surface 34a and the second end surface 37 are rounded. A corner between the second side surface 34b and the first end surface 36 and a corner between the second side surface 34b and the second end surface 37 are rounded.

[0136] The first end surface 36 may be flat as shown by the solid line in FIG. 3, or may be convex toward the Z2 direction as shown by the two-dot chain line in FIG. 3, regardless of whether the core pieces 1 are used to construct a stator core 7 for an axial gap type rotating electric machine 9 of the DS / SR type or an axial gap type rotating electric machine 9 of the SS / DR type. If the first end surface 36 is convex, an axial gap type rotating electric machine 9 with low noise and vibration can be constructed. The reason is as follows. In the axial gap type rotating electric machine 9, as shown in FIG. 18 or FIG. 19, the stator 8 and the rotor 90 are arranged facing each other. As shown in FIG. 17, the stator 8 includes a stator core 7 and a coil 80. As shown in FIG. 16 and FIG. 17, the stator core 7 is configured by arranging a plurality of core pieces 1 in an annular shape. As shown in FIG. 17, the coil 80 is arranged in the first member 10 of each core piece 1. As shown by the two-dot chain line in Fig. 3, the first end face 36 of the third member 30 of the core piece 1 is provided in a convex shape, so that in the axial gap type rotating electric machine 9 shown in Figs. 18 and 19, a sudden change in the magnetic flux of the magnet 95 of the rotor 90 received by the core piece 1 is easily suppressed. Therefore, the cogging torque is easily reduced. Since the cogging torque is small, noise and vibration are unlikely to increase.

[0137] It is preferable that corners 38 between the first end face 36 and the outer peripheral surface 32, and corners 38 between the first end face 36 and the inner peripheral surface 33 are chamfered. These corners 38 are less likely to be damaged by being chamfered. These chamfers may be C-chamfered or R-chamfered. The chamfered length of corners 38 is preferably, like the chamfered length of corners 28, 0.1 mm or more and 0.5 mm or less, more preferably 0.15 mm or more and 0.45 mm or less, and particularly preferably 0.2 mm or more and 0.4 mm or less.

[0138] [Seam] As shown in FIG. 3, the first joint between the protruding portion 21 of the second member 20 and the peripheral surface 11 of the first member 10, and the second joint between the protruding portion 31 of the third member 30 and the peripheral surface 11 of the first member 10 are rounded. In this embodiment, the first joint includes the joint between the first protruding portion 211 of the second member 20 and the peripheral surface 11 of the first member 10, and the joint between the second protruding portion 212 of the second member 20 and the peripheral surface 11 of the first member 10. These joints are rounded. The second joint includes the joint between the first protruding portion 311 of the third member 30 and the peripheral surface 11 of the first member 10, and the joint between the second protruding portion 312 of the third member 30 and the peripheral surface 11 of the first member 10. These joints are rounded. Since each joint has a rounded shape, the core piece 1 is less likely to be damaged starting from the joint.

[0139] The bending radius of the first joint and the bending radius of the second joint are preferably 0.2 mm or more and 4.0 mm or less. When the bending radius of the first joint and the second joint is 0.2 mm or more, the load on the die during the manufacturing of the core piece 1 is small. When the bending radius of the first joint and the second joint is 4.0 mm or less, it is easy to wind the coil 80 when constructing the stator 8 described later with reference to FIG. 17, so that the number of turns of the coil 80 is easily increased. The bending radius of the first joint and the second joint is further preferably 0.3 mm or more and 3.0 mm or less, and particularly preferably 0.5 mm or more and 2.0 mm or less. The bending radius of the first joint and the bending radius of the second joint may be the same as each other or may be different from each other.

[0140] [Area ratio] The total area of ​​the outer peripheral surfaces 12, 22, 32 of the first member 10, the second member 20, and the third member 30 is preferably more than 1 time and not more than 4 times the total area of ​​the inner peripheral surfaces 13, 23, 33 of the first member 10, the second member 20, and the third member 30. The core pieces 1 whose total area of ​​the outer peripheral surfaces 12, 22, 32 is more than 1 time the total area of ​​the inner peripheral surfaces 13, 23, 33 are easy to arrange in an annular shape and are easy to construct the stator core 7. The core pieces 1 whose total area of ​​the outer peripheral surfaces 12, 22, 32 is not more than 4 times the total area of ​​the inner peripheral surfaces 13, 23, 33 are easy to manufacture. Since the ratio of the total area of ​​the inner peripheral surfaces 13, 23, 33 is relatively high, the area pushed out by the lower punch 55 is large when the core pieces 1 are extracted from the die 5. Therefore, it is easy to suppress damage to the core pieces 1 when they are extracted from the die 5. The total area of ​​the outer circumferential surfaces 12, 22, 32 is preferably 1.2 times or more and 3.8 times or less, and particularly preferably 1.5 times or more and 3.5 times or less, of the total area of ​​the inner circumferential surfaces 13, 23, 33.

[0141] [Material] As shown in FIG. 8 and FIG. 9, the green compact has a plurality of soft magnetic particles 40. The green compact is preferably composed of an aggregate of a plurality of coated soft magnetic particles 4. The coated soft magnetic particles 4 have soft magnetic particles 40 and insulating coatings 41 that cover the surfaces of the soft magnetic particles 40. If the insulating coatings 41 are formed, the insulating coatings 41 can easily ensure electrical insulation between the soft magnetic particles 40. Therefore, the iron loss of the green compact caused by eddy current loss can be reduced. The material of the soft magnetic particles 40 can be pure iron or an iron-based alloy. Pure iron refers to iron (iron) having a purity of 99 mass% or more. The iron-based alloy contains at least one element of Si (silicon) and Al (aluminum), with the balance being Fe and unavoidable impurities. The iron-based alloy can be at least one selected from the group consisting of Fe-Si alloys, Fe-Al alloys, and Fe-Si-Al alloys. An example of an Fe-Si alloy is silicon steel. An example of an Fe-Si-Al alloy is sendust. Since the above material is relatively soft, the soft magnetic particles 40 are easily deformed during molding of the powder compact. Therefore, the core piece 1 has a high density and excellent dimensional accuracy. Examples of the insulating coating 41 include a phosphate coating and a silica coating.

[0142] [Shape of soft magnetic particles] The powder compact is obtained by compression molding a soft magnetic powder having a plurality of soft magnetic particles 40. Alternatively, the powder compact is obtained by compression molding a coated soft magnetic powder having a plurality of coated soft magnetic particles 4. That is, the shape of the soft magnetic particles 40 is flat. The soft magnetic particles 40 have a major axis and a minor axis in a first cross section of the first member 10, a second cross section of the second member 20, and a third cross section of the third member 30, which will be described later.

[0143] [First average aspect ratio] In the first cross section of the first member 10 shown in FIG. 7, the first average aspect ratio of the soft magnetic particles 40 shown in FIG. 8 is 1.2 or more. The first cross section is a cross section along the X-axis direction and the Z-axis direction. The first average aspect ratio is the ratio L12 / L11 of the average length L11 to the average length L12 in the first cross section. The average length L11 is the average length of the soft magnetic particles 40 along the X-axis direction. The average length L12 is the average length of the soft magnetic particles 40 along the Z-axis direction. The larger the first average aspect ratio, the longer the length of the soft magnetic particles 40 along the Z-axis direction is in the first cross section of the first member 10 than the length along the X-axis direction.

[0144] A square first observation field is taken on the first cross section of the first member 10. The first observation field is taken to have a pair of first sides along the Z-axis direction and a pair of second sides along the X-axis direction. When the first average aspect ratio of the soft magnetic particles 40 satisfies 1.2 or more, the number of soft magnetic particles 40 aligned in the Z-axis direction is smaller than the number of soft magnetic particles 40 aligned in the X-axis direction in the first observation field. That is, the number of grain boundaries dividing the Z-axis direction is smaller in the first observation field. The grain boundaries refer to the spaces between adjacent soft magnetic particles.

[0145] The first average aspect ratio is more preferably 1.25 or more, and particularly preferably 1.3 or more. The upper limit of the first average aspect ratio is, for example, about 1.7. That is, the first average aspect ratio is preferably 1.2 or more and 1.7 or less, more preferably 1.25 or more and 1.6 or less, and particularly preferably 1.3 or more and 1.5 or less.

[0146] The average length L11 and the average length L12 are determined as follows. On the first cross section, a first virtual line is drawn along the X-axis direction. The length of the first virtual line is, for example, 1000 μm. The number of soft magnetic particles 40 present on the first virtual line is counted. The length of the first virtual line is divided by the total number of soft magnetic particles 40 counted. The divided value is defined as length L11. Similarly, on the first cross section, a second virtual line is drawn along the Z-axis direction. The length of the second virtual line is, for example, 1000 μm. The number of soft magnetic particles 40 present on the second virtual line is counted. The length of the second virtual line is divided by the total number of soft magnetic particles 40 counted. The divided value is defined as length L12.

[0147] [Second average aspect ratio] In the second cross section of the second member 20 shown in FIG. 5, the soft magnetic particles 40 have a second average aspect ratio of 1.2 or more. The second cross section is a cross section perpendicular to the Z-axis direction. The second average aspect ratio is the ratio L22 / L21 of the average length L21 to the average length L22 in the second cross section. The average length L21 is the average length of the soft magnetic particles 40 along the X-axis direction. The average length L22 is the average length of the soft magnetic particles 40 along the circumferential direction of the stator core 7. The larger the second average aspect ratio, the longer the length of the soft magnetic particles 40 along the circumferential direction of the stator core 7 is in the second cross section of the second member 20 than the length along the X-axis direction.

[0148] A square second observation field is taken in the second cross section of the second member 20. The second observation field is taken so as to have a pair of first sides along the X-axis direction and a pair of second pieces along the Y-axis direction. When the second average aspect ratio of the soft magnetic particles 40 satisfies 1.2 or more, the number of soft magnetic particles 40 aligned in the circumferential direction of the stator core 7 is smaller than the number of soft magnetic particles 40 aligned in the X-axis direction in the second observation field. That is, the number of grain boundaries dividing the circumferential direction of the stator core 7 is smaller in the second observation field. The preferred numerical range of the second average aspect ratio is the same as the preferred numerical range of the first average aspect ratio described above.

[0149] The average length L21 and the average length L22 are obtained as follows. In the second cross section, a first virtual line is drawn along the X-axis direction. The length of the first virtual line is, for example, 1000 μm. The number of soft magnetic particles 40 present on the first virtual line is counted. The length of the first virtual line is divided by the total number of the counted soft magnetic particles 40. The divided value is the length L21. Similarly, in the second cross section, a second virtual line is drawn along the circumferential direction of the stator core 7. The second virtual line is an arc line that is convex in the X2 direction. In this embodiment, the second virtual line is an arc line that is concentric with the outer periphery of the second member 20. The length of the second virtual line is, for example, 1000 μm. The number of soft magnetic particles 40 present on the second virtual line is counted. The length of the second virtual line is divided by the total number of the counted soft magnetic particles 40. The divided value is the length L22.

[0150] [Third average aspect ratio] In the third cross section of the third member 30 shown in FIG. 6, the third average aspect ratio of the soft magnetic particles is 1.2 or more. The third cross section is a cross section perpendicular to the Z-axis direction. The third average aspect ratio is the ratio L32 / L31 of the average length L31 to the average length L32 in the third cross section. The average length L31 is the average length of the soft magnetic particles 40 along the X-axis direction. The average length L32 is the average length of the soft magnetic particles 40 along the circumferential direction of the stator core 7. The larger the third average aspect ratio, the longer the length of the soft magnetic particles 40 along the circumferential direction of the stator core 7 in the third cross section of the third member 30 is than the length along the X-axis direction.

[0151] In the third cross section of the third member 30, a third observation field of a square shape similar to the second observation field described above is taken. When the third average aspect ratio of the soft magnetic particles 40 satisfies 1.2 or more, the number of the soft magnetic particles 40 aligned in the circumferential direction of the stator core 7 is smaller than the number of the soft magnetic particles 40 aligned in the X-axis direction in the third observation field. That is, in the third observation field, the number of grain boundaries dividing the circumferential direction of the stator core 7 is smaller. The preferable numerical range of the third average aspect ratio is the same as the preferable numerical range of the first average aspect ratio described above. The method of determining the average length L31 and the average length L32 is the same as the method of determining the average length L21 and the average length L22.

[0152] [Average particle size] The average particle size of the soft magnetic particles 40 is preferably, for example, 30 μm or more. When the average particle size of the soft magnetic particles 40 is 30 μm or more, the relative permeability is likely to be large. The core piece 1 including the soft magnetic particles 40 has low loss. Therefore, the core piece 1 is easy to construct an axial gap type rotating electric machine 9 with low loss. The average particle size of the soft magnetic particles 40 can further be 40 μm or more, and particularly 50 μm or more. The upper limit of the average particle size of the soft magnetic particles 40 is, for example, 500 μm. When the average particle size of the soft magnetic particles 40 is 500 μm or less, the eddy current loss of the soft magnetic particles 40 itself is likely to be small. The core piece 1 including the soft magnetic particles 40 is easy to construct an axial gap type rotating electric machine 9 with excellent magnetic properties. That is, the average particle size of the soft magnetic particles 40 is 30 μm or more and 500 μm or less, further 40 μm or more and 450 μm or less, and particularly 50 μm or more and 400 μm or less.

[0153] The average particle size of the soft magnetic particles 40 is obtained as follows. The cross section of the core piece 1 is observed with a SEM (scanning electron microscope). The cross section is prepared with a cross-section polisher device. This cross section is a cross section along both the X-axis direction and the Z-axis direction. An observation image of the cross section is obtained. The magnification of the SEM is 150 times or more and 500 times or less. The size of the observation image is 800 μm × 800 μm, for example. The number of observation images obtained is 50 or more. One observation image may be obtained for one cross section, or multiple observation images may be obtained for one cross section. The obtained observation images are subjected to image processing to extract the contours of the soft magnetic particles. Examples of image processing include binarization processing. The area is obtained for each of all soft magnetic particles present in each observation image. The diameter of a circle having the same area as each area is obtained. The average value of all the obtained diameters is obtained. This average value is the average particle size of the soft magnetic particles 40. The number of measurements for obtaining the average particle size is, for example, 200 or more.

[0154] [Magnetic path] When an axial gap type rotating electric machine 9 as shown in FIG. 18 is constructed using the core pieces 1, magnetic flux passes through the core pieces 1. For example, as shown by the white arrows in FIG. 10, the magnetic flux passes through the second member 20, the first member 10, and the third member 30 in this order. Alternatively, although the white arrows are omitted, the magnetic flux passes through the third member 30, the first member 10, and the second member 20 in this order. The magnetic flux passing through the second member 20 is along the surface direction of the second member 20. That is, the magnetic flux passing through the second member 20 is along the circumferential direction of the stator core 7. The magnetic flux passing through the first member 10 is along the Z-axis direction. The magnetic flux passing through the third member 30 is along the surface direction of the third member 30. That is, the magnetic flux passing through the third member 30 is along the circumferential direction of the stator core 7. The magnetic flux passing through the second member 20 and the magnetic flux passing through the third member 30 are parallel to each other. The magnetic flux passing through the second member 20 and the magnetic flux passing through the first member 10 are aligned in different directions.

[0155] As described above, since the first average aspect ratio of the soft magnetic particles 40 in the first cross section of the first member 10 is 1.2 or more, in the first cross section, the length of the soft magnetic particles 40 along the magnetic flux is longer than the length along the direction perpendicular to the magnetic flux. That is, in the above-mentioned first observation field of the first cross section, the number of soft magnetic particles 40 aligned in the direction of the magnetic flux is smaller than the number of soft magnetic particles 40 aligned in the direction perpendicular to the direction of the magnetic flux. In the first observation field, the number of grain boundaries that divide the direction along the magnetic flux is small.

[0156] Furthermore, as described above, since the second average aspect ratio of the soft magnetic particles 40 in the second cross section of the second member 20 is 1.2 or more, in the second cross section, the length of the soft magnetic particles 40 along the magnetic flux is longer than the length along the direction perpendicular to the magnetic flux. That is, in the above-mentioned second observation field of the second cross section, the number of soft magnetic particles 40 aligned in the direction of the magnetic flux is smaller than the number of soft magnetic particles 40 aligned in the direction perpendicular to the direction of the magnetic flux. In the second observation field, the number of grain boundaries that divide the direction along the magnetic flux is small.

[0157] Furthermore, as described above, since the third average aspect ratio of the soft magnetic particles 40 in the third cross section of the third member 30 is 1.2 or more, in the third cross section, the length of the soft magnetic particles 40 along the magnetic flux is longer than the length along the direction perpendicular to the magnetic flux. That is, in the above-mentioned third observation field of the third cross section, the number of soft magnetic particles 40 aligned in the direction of the magnetic flux is smaller than the number of soft magnetic particles 40 aligned in the direction perpendicular to the direction of the magnetic flux. In the third observation field, the number of grain boundaries dividing the direction along the magnetic flux is small.

[0158] As described below, such a core piece 1 can be manufactured by pressing the raw material powder filled in the die hole of a metal mold with an upper punch and a lower punch, with the pressure direction and the punching direction being aligned along the X-axis direction of the core piece 1.

[0159] Here, a case where the pressurizing direction and the pulling direction are different from the pressurizing direction and the pulling direction when manufacturing the core piece 1 of this embodiment, and are the direction along the axial direction of the stator core in the core piece, is considered. In this case, it is not possible to manufacture the core piece 1 including the first member 10, the second member 20, and the third member 30 as in this embodiment. As described above, since the second member 20 and the third member 30 each have the protruding parts 21, 31, the protruding parts 21, 31 are caught on the inner peripheral surface of the mold hole of the die, and the core piece 1 cannot be removed from the mold. If the core piece includes the first member and the second member without the third member, it can be manufactured even if the pressurizing direction and the pulling direction are the direction along the axial direction of the stator core in the core piece. A core piece including the first member and the second member without the third member and manufactured with the pressurizing direction and the pulling direction being the direction along the axial direction of the stator core in the core piece is a conventional core piece.

[0160] A first cross section of the conventional core piece first member is similar to the first cross section of the first member of core piece 1 of the present embodiment. Also, a second cross section of the conventional core piece second member is similar to the second cross section of the second member of core piece 1 of the present embodiment.

[0161] In the first cross section of the first member of the conventional core piece, unlike the first cross section of the first member 10 of the core piece 1 of the present embodiment, the length of the soft magnetic particles along the axial direction of the stator core is shorter than the length along the radial direction of the stator core. In the first cross section of the conventional core piece, a square first observation field similar to the above-mentioned first observation field is taken. In the first observation field of the conventional core piece, unlike the first observation field of the core piece 1 of the present embodiment, the number of soft magnetic particles aligned in the axial direction of the stator core is greater than the number of soft magnetic particles aligned in the radial direction of the stator core. That is, in the first observation field of the conventional core piece, unlike the first observation field of the core piece 1 of the present embodiment, the number of grain boundaries dividing the axial direction of the stator core is greater. The magnetic flux passing through the first member of the conventional core piece is along the axial direction of the stator core, similar to the second member 20 of the core piece 1 of the present embodiment. That is, in the first observation field of the conventional core piece, the number of soft magnetic particles aligned in the direction of the magnetic flux is greater than the number of soft magnetic particles aligned in the direction perpendicular to the direction of the magnetic flux, unlike the first observation field of the core piece 1 of the present embodiment. In the first observation field of the conventional core piece, the number of grain boundaries dividing the direction along the magnetic flux is greater than the first observation field of the core piece 1 of the present embodiment.

[0162] In the second cross section of the second member of the conventional core piece, unlike the second cross section of the second member 20 of the core piece 1 of the present embodiment, the length of the soft magnetic particles along the circumferential direction of the stator core is approximately the same as the length along the radial direction of the stator core. In the second cross section of the conventional core piece, a square second observation field similar to the above-mentioned second observation field is taken. In the second observation field of the conventional core piece, unlike the second observation field of the core piece 1 of the present embodiment, the number of soft magnetic particles aligned in the circumferential direction of the stator core is approximately the same as the number of soft magnetic particles aligned in the radial direction of the stator core. That is, in the second observation field of the conventional core piece, unlike the second observation field of the core piece 1 of the present embodiment, the number of grain boundaries dividing the circumferential direction of the stator core is approximately the same as the number of grain boundaries dividing the radial direction of the stator core. The magnetic flux passing through the second member of the conventional core piece is along the circumferential direction of the stator core, similar to the second member 20 of the core piece 1 of the present embodiment. That is, in the second observation field of the conventional core piece, unlike the second observation field of the core piece 1 of the present embodiment, the number of soft magnetic particles aligned in the direction of the magnetic flux is approximately the same as the number of soft magnetic particles aligned in the direction perpendicular to the direction of the magnetic flux. In the second observation field of the conventional core piece, unlike the second observation field of the core piece 1 of the present embodiment, the number of grain boundaries dividing the direction along the magnetic flux is approximately the same as the number of grain boundaries dividing the direction perpendicular to the direction of the magnetic flux.

[0163] The first member 10 of the core piece 1 of this embodiment has a smaller number of grain boundaries that divide the direction along the magnetic flux than the first member of the conventional core piece. These grain boundaries become magnetic gaps. The larger the magnetic gap, the larger the magnetic resistance. Therefore, the first member 10 of the core piece 1 of this embodiment allows magnetic flux to pass through more easily than the first member of the conventional core piece. The second member 20 of the core piece 1 of this embodiment and the second member of the conventional core piece allow magnetic flux to pass through with the same degree of ease. Therefore, the core piece 1 of this embodiment allows magnetic flux to pass through more easily than the conventional core piece. Therefore, the core piece 1 of this embodiment makes it easier to construct an axial gap type rotating electric machine 9 with excellent magnetic characteristics than the conventional core piece. The more core pieces that constitute the stator core provided in the axial gap type rotating electric machine 9, the easier it is to construct an axial gap type rotating electric machine 9 with excellent magnetic characteristics than the conventional core piece. As described above, when the proportion of the second height H10 in the first height H1 is 80% or more, the proportion of the region excluding the second member 20 in the core piece 1, in this example the first member 10 and the third member 30, tends to be high. Therefore, when the second height H10 of the region excluding the second member 20 in the core piece 1 of the present embodiment and the height of the region excluding the second member in the conventional core piece are constant, the core piece 1 of the present embodiment makes it easier to construct an axial gap type rotating electric machine 9 having superior magnetic characteristics compared to the conventional core piece.

[0164] Relative Density The relative density of the powder compact is preferably 85% or more. Powder compacts with a relative density of 85% or more are excellent in magnetic properties such as saturation magnetic flux density, and mechanical properties such as strength. The relative density of the powder compact is more preferably 90% or more, and particularly preferably 93% or more. The relative density of the powder compact may be less than 100%. "Relative density" refers to the ratio (%) of the actual density of the powder compact to the true density of the soft magnetic particles that make up the powder compact.

[0165] [Relative density difference] Of the first, second, and third parts in the core piece 1, the difference in relative density between the first and second parts and the third part is preferably 5.0% or less. Since the difference in relative density is small in this core piece 1, physical properties such as magnetic properties are substantially uniform within the core piece 1. The smaller the difference in relative density between the first and second parts and the third part, the more preferable it is. The difference in relative density between the first and second parts and the third part is more preferably 4.0% or less, and particularly preferably 3.0% or less. Here, as shown in FIG. 2, among the parts obtained by dividing the core piece 1 into three parts by a virtual plane Va along the second parallel plane of the first side surface and a virtual plane Vb along the second parallel plane of the second side surface, the part on the first direction side in the circumferential direction is the first part, the part on the second direction side in the circumferential direction is the second part, and the part between the first and second parts is the third part.

[0166] Of the first member 10, the second member 20, and the third member 30, it is preferable that the difference in relative density between the member with the highest relative density and the member with the lowest relative density is 5.0% or less. Since the difference in relative density is small in this core piece 1, the physical properties such as magnetic properties are substantially uniform within the core piece 1. The smaller the difference in relative density between the member with the highest relative density and the member with the lowest relative density, the more preferable. The difference in relative density between the member with the highest relative density and the member with the lowest relative density is further preferably 4.0% or less, and particularly preferably 3.0% or less.

[0167] It is preferable that the difference in relative density between the first and second regions and the third region is 5.0% or less, and the difference in relative density between the member with the highest relative density and the member with the lowest relative density is 5.0% or less.

[0168] [Action and Effect] The core piece 1 of this embodiment allows magnetic flux to easily pass through any of the first member 10, the second member 20, and the third member 30, and therefore makes it easy to construct an axial gap type rotating electric machine 9 with excellent magnetic properties. The core piece 1 of this embodiment is made of a powder compact in which the first member 10, the second member 20, and the third member 30 are integrally molded, and therefore has excellent productivity.

[0169] [Method of manufacturing core pieces] The manufacturing method of the core piece according to the first embodiment includes a filling step and a molding step. In the filling step, raw material powder is filled into a die 5. The raw material powder includes a plurality of spherical soft magnetic particles. In the molding step, the raw material powder in the die 5 is compressed to form a compact. The manufacturing method of the core piece according to this embodiment can manufacture the core piece 1 according to this embodiment. First, the die 5 will be described with reference to Figs. 11 to 14, and then each step will be described.

[0170] [Mold] The mold 5 includes a die 50, an upper punch 54, and a lower punch 55. A cavity is formed by the die 50 and the lower punch 55. The cavity is filled with raw material powder.

[0171] (Thailand) The die 50 has a die hole 50h. In the die hole 50h, an upper punch 54 and a lower punch 55 are arranged to face each other. The inner peripheral shape of the die hole 50h corresponds to the shape of the core piece 1. The upper punch 54 can be driven independently in the vertical direction with respect to the die 50. The lower punch 55 can be driven independently in the vertical direction with respect to the die 50.

[0172] The mold hole 50h has a first hole portion 51 shown in FIG. 11 and FIG. 12, a second hole portion 52 shown in FIG. 11 and FIG. 13, and a third hole portion 53 shown in FIG. 11 and FIG. 14. FIG. 11 shows the opening edge of the mold hole 50h of the die 50 on the upper punch 54 side. For convenience of explanation, FIG. 11 shows the die 50 with hatching. FIG. 12 to FIG. 14 are cross-sectional views showing a state in which the raw material powder filled in the cavity is pressure-molded by the upper punch 54 and the lower punch 55. The cutting position of the cross-sectional view of FIG. 12 corresponds to the position shown by the XII-XII cutting line in FIG. 11. The cutting position of the cross-sectional view of FIG. 13 corresponds to the position shown by the XIII-XIII cutting line in FIG. 11. The cutting position of the cross-sectional view of FIG. 14 corresponds to the position shown by the XIV-XIV cutting line in FIG. 11.

[0173] The first hole portion 51 has an inner peripheral surface that forms the first side surface 14a and the second side surface 14b of the first member 10. The second hole portion 52 has an inner peripheral surface that forms the first side surface 24a, the second side surface 24b, the first end surface 26, and the second end surface 27 of the second member 20. The third hole portion 53 has an inner peripheral surface that forms the first side surface 34a, the second side surface 34b, the first end surface 36, and the second end surface 37 of the third member 30. The first hole portion 51, the second hole portion 52, and the third hole portion 53 are formed in a continuous manner in a direction perpendicular to the direction in which the upper punch 54 and the lower punch 55 face each other. Specifically, the second hole portion 52 communicates with the first end side of the first hole portion 51 in the perpendicular direction. Also, the third hole portion 53 communicates with the second end side of the first hole portion 51 in the perpendicular direction.

[0174] The first hole portion 51 includes a first straight portion 511, a second straight portion 512, and a tapered portion 513. The first straight portion 511, the tapered portion 513, and the second straight portion 512 are formed in a continuous manner in order from the upper punch 54 side toward the lower punch 55 side. Similarly, the second hole portion 52 includes a first straight portion 521, a second straight portion 522, and a tapered portion 523. The first straight portion 521, the tapered portion 523, and the second straight portion 522 are formed in a continuous manner in order from the upper punch 54 side toward the lower punch 55 side. Similarly, the third hole portion 53 includes a first straight portion 531, a second straight portion 532, and a tapered portion 533. The first straight portion 531, the tapered portion 533, and the second straight portion 532 are formed in a continuous manner in order from the upper punch 54 side toward the lower punch 55 side. The first straight portions 511, 521, 531 form the outer peripheral surface side portion of the core piece 1. The second straight portions 512, 522, 532 form the inner peripheral surface side portion of the core piece 1. The tapered portions 513, 523, 533 form the portion between the outer peripheral surface side and the inner peripheral surface side of the core piece 1.

[0175] (Upper punch) The upper punch 54 has a first upper punch portion 541 shown in FIG. 12, a second upper punch portion 542 shown in FIG. 13, and a third upper punch portion 543 shown in FIG. 14. The first upper punch portion 541 has a first lower end surface 541e. The first lower end surface 541e forms the outer peripheral surface 12 of the first member 10. The second upper punch portion 542 has a second lower end surface 542e. The second lower end surface 542e forms the outer peripheral surface 22 of the second member 20. The third upper punch portion 543 has a third lower end surface 543e. The third lower end surface 543e forms the outer peripheral surface 32 of the third member 30. The first upper punch portion 541, the second upper punch portion 542, and the third upper punch portion 543 may be formed in a continuous manner, or may be formed independently of each other so as to be independently movable up and down. When the first upper punch portion 541, the second upper punch portion 542, and the third upper punch portion 543 are formed in a continuous manner, the first lower end surface 541e, the second lower end surface 542e, and the third lower end surface 543e are formed in a continuous manner. The shape of the first lower end surface 541e corresponds to the shape of the outer peripheral surface 12 of the first member 10. The shape of the second lower end surface 542e corresponds to the shape of the outer peripheral surface 22 of the second member 20. The shape of the third lower end surface 543e corresponds to the shape of the outer peripheral surface 32 of the third member 30.

[0176] (Lower punch) The lower punch 55 has a first lower punch portion 551 shown in FIG. 12, a second lower punch portion 552 shown in FIG. 13, and a third lower punch portion 553 shown in FIG. 14. The first lower punch portion 551 has a first upper end surface 551e. The first upper end surface 551e forms the inner peripheral surface 13 of the first member 10. The second lower punch portion 552 has a second upper end surface 552e. The second upper end surface 552e forms the inner peripheral surface 23 of the second member 20. The third lower punch portion 553 has a third upper end surface 553e. The third upper end surface 553e forms the inner peripheral surface 33 of the third member 30. The first lower punch portion 551, the second lower punch portion 552, and the third lower punch portion 553 may be formed in a continuous manner, or may be formed independently of each other so as to be independently movable up and down. When the first lower punch portion 551, the second lower punch portion 552, and the third lower punch portion 553 are formed in a continuous manner, the first upper end surface 551e, the second upper end surface 552e, and the third upper end surface 553e are formed in a continuous manner. The shape of the first upper end surface 551e corresponds to the shape of the inner circumferential surface 13 of the first member 10. The shape of the second upper end surface 552e corresponds to the shape of the inner circumferential surface 23 of the second member 20. The shape of the third upper end surface 553e corresponds to the shape of the inner circumferential surface 33 of the third member 30.

[0177] [Filling process] The cavity formed by the die 50 and the lower punch 55 is filled with raw material powder. The above-mentioned soft magnetic powder or coated soft magnetic powder can be used as the raw material powder. The shape of the soft magnetic particles is preferably spherical. In addition to the soft magnetic powder or coated soft magnetic powder, the raw material powder may contain a binder and a lubricant. A lubricant may be applied to the inner peripheral surface of the die hole 50h of the die 50.

[0178] [Molding process] The raw material powder in the cavity is compression molded by the upper punch 54 and the lower punch 55. The direction in which the raw material powder is compressed is along the radial direction of the stator core 7. The higher the pressure during compression molding, the higher the relative density of the core pieces 1 produced. The pressure may be, for example, 700 MPa or more, and further may be 980 MPa or more.

[0179] [Other processes] After the compacting step, a heat treatment may be performed as necessary. For example, the heat treatment may be used to remove distortion, thereby producing a low-loss core piece 1. Alternatively, for example, the heat treatment may be used to remove binders and lubricants. When the raw powder contains the coated soft magnetic particles 4 described above, the heat treatment temperature is preferably equal to or lower than the decomposition temperature of the insulating coating.

[0180] [Action and Effect] The core piece manufacturing method of the present embodiment can manufacture the above-described core piece 1 of the present embodiment. That is, the core piece manufacturing method of the present embodiment can manufacture the core piece 1 that is easy to construct into an axial gap type rotating electric machine 9 with excellent magnetic characteristics. Furthermore, the core piece manufacturing method of the present embodiment can integrally mold the first member 10, the second member 20, and the third member 30, so that the productivity of the core pieces can be easily improved.

[0181] Second Embodiment [Core piece] A core piece 1 according to a second embodiment will be described with reference to Fig. 15. The core piece 1 of this embodiment differs from the core piece 1 according to the first embodiment mainly in that the core piece 1 does not include a third member.

[0182] In the case where a third member is not provided as in this embodiment, the first height of the core piece 1 is the length between the first end face 26 and the end face 16 of the first member 10. The second height is the height of the first member 10, i.e., the length between the second end face 27 and the end face 16 of the first member 10.

[0183] It is preferable that the corners between the outer circumferential surface and end face 16 of the first member 10, and the corners 18 between the inner circumferential surface and end face 16 of the first member 10 are chamfered. These chamfers may be C-chamfered or R-chamfered, similar to the above-mentioned corners 28. The preferred numerical range for the chamfer length of corners 18 is the same as the preferred numerical range for the chamfer length of corners 28.

[0184] In the first member 10 of this embodiment, the soft magnetic particles 40 have a first average aspect ratio of 1.2 or more in the first cross section, similar to the first member 10 of the core piece 1 of embodiment 1. The preferred numerical range of the first average aspect ratio is the same as that of embodiment 1.

[0185] In the second member 20 of this embodiment, the second average aspect ratio of the soft magnetic particles 40 in the second cross section is 1.2 or more, similar to the second member 20 of the core piece 1 of embodiment 1. The suitable numerical range of the second average aspect ratio is the same as that of embodiment 1.

[0186] [Action and Effect] Like the core pieces 1 of the first embodiment, the core pieces 1 of this embodiment make it easy to construct an axial gap type rotating electric machine 9 having excellent magnetic characteristics.

[0187] Third Embodiment [Stator core] A stator core 7 according to the third embodiment will be described with reference to FIG. 16. The stator core 7 according to the present embodiment has a plurality of core pieces 1 arranged in an annular shape. Each of the plurality of core pieces 1 in the present embodiment is the core piece 1 according to the first embodiment. Unlike the present embodiment, each of the plurality of core pieces 1 may be the core piece 1 according to the second embodiment. The plurality of core pieces 1 in the present embodiment are assembled in an annular shape such that the step 240 of the first side surface 24a of the second member 20 of the first core piece 1 and the step 240 of the second side surface 24b of the second member 20 of the second core piece 1 among the core pieces 1 adjacent in the circumferential direction are fitted together. This stator core 7 is used in an axial gap type rotating electric machine 9 of the DS / SR type shown in FIG. 18.

[0188] It is preferable that the variation in the length between the face on the first end side and the face on the second end side in the Z-axis direction in each of the multiple core pieces 1 is 0.1 mm or less. The length between the face on the first end side and the face on the second end side in the Z-axis direction is the maximum length between the first end face 26 of the second member 20 and the first end face 36 of the third member 30.

[0189] If the variation in length between the first end face 26 of the second member 20 and the first end face 36 of the third member 30 in each of the multiple core pieces 1 is 0.1 mm or less, the variation in the length is very small. Therefore, the stator core 7 can be used to construct an axial gap type rotating electric machine 9 that produces little noise and vibration. The reason is as follows. In the axial gap type rotating electric machine 9, the stator 8 and the rotor 90 are arranged to face each other as shown in FIG. 18. Since the variation in the length of the stator core 7 is small, the variation in the interval between the stator 8 and the rotor 90 is small. Since the variation in the interval is small, the torque ripple is small. Since the torque ripple is small, noise and vibration are unlikely to increase. The variation in the length is obtained as follows. In each core piece 1, the length from the first end face 26 of the second member 20 to the first end face 36 of the third member 30 is measured. This length is the maximum length of the core piece 1 along the Z-axis direction. The difference between the maximum and minimum values ​​of the above length is calculated for each of the multiple core pieces 1. This difference is defined as the variation in the length. The variation in the length between the first end face 26 of the second member 20 and the first end face 36 of the third member 30 for each of the multiple core pieces 1 is further preferably 0.05 mm or less, and particularly preferably 0.01 mm or less.

[0190] [Action and Effect] The stator core 7 of the present embodiment has multiple core pieces constituting the stator core 7, each of which is configured with the core pieces 1 of the first embodiment that allow magnetic flux to easily pass therethrough, and therefore it is easy to construct an axial gap type rotating electric machine 9 with excellent magnetic properties. Also, the stator core 7 of the present embodiment has excellent productivity, since the multiple core pieces constituting the stator core 7 are configured with the core pieces 1 of the first embodiment that have excellent productivity.

[0191] Fourth Embodiment [Stator] A stator 8 according to the fourth embodiment will be described with reference to Fig. 17. The stator 8 of this embodiment includes a stator core 7 and a coil 80. The stator core 7 according to the third embodiment can be used as the stator core 7. The coil 80 is wound around the first member 10 in each core piece 1 of the stator core 7. This stator 8 is used in an axial gap type rotating electric machine 9 of a DS / SR configuration shown in Fig. 18.

[0192] Each coil 80 has a cylindrical portion formed by winding a wire. The winding is made of a covered round wire. The covered round wire has a round wire conductor and an edge coating provided on the outer periphery of the conductor. Note that FIG. 17 shows only the cylindrical portion of each coil 80 in a simplified manner, and both ends of the winding are not shown. The stator core 7 can be produced by winding a wire around the outside of the first member 10 of each core piece 1.

[0193] [Action and Effect] Since the stator 8 of this embodiment includes the stator core 7 of the third embodiment, it is easy to construct an axial gap type rotating electric machine 9 having excellent magnetic characteristics. In addition, since the stator 8 of this embodiment includes the stator core 7 of the third embodiment, which has excellent productivity, it has excellent productivity.

[0194] Fifth Embodiment [Rotary Electric Machine] With reference to FIG. 18, a rotating electric machine 9 according to a fifth embodiment will be described. FIG. 18 is a cross-sectional view taken along a plane parallel to a rotating shaft 91 of the rotating electric machine 9 and passing through the circumferential center of the core piece 1. This point is similar to FIG. 19 to be referred to in a sixth embodiment described later. The rotating electric machine 9 according to this embodiment is an axial gap type rotating electric machine. The rotating electric machine 9 according to this embodiment is a DS / SR type having one rotor 90 and two stators 8. That is, in the rotating electric machine 9, the rotor 90 and the stator 8 are arranged to face each other in the axial direction. The one rotor 90 is assembled so as to be sandwiched between the two stators 8. The stator 8 according to the fourth embodiment described above can be used for each stator 8. The rotating electric machine 9 can be used as a motor or a generator. The rotating electric machine 9 has a case 92.

[0195] The case 92 has a cylindrical internal space for housing the stator 8 and the rotor 90. The case 92 includes a cylindrical portion 921 and two plates 922. The cylindrical portion 921 surrounds the outer periphery of the stator 8 and the rotor 90. A plate 922 is disposed on each end of the cylindrical portion 921. The two plates 922 are fixed to both end faces of the cylindrical portion 921 so as to sandwich the stator 8 and the rotor 90 from both sides in the axial direction. Both plates 922 include a through hole in the center. A bearing 93 is provided in the through hole. The rotating shaft 91 is inserted into the through hole via the bearing 93. The rotating shaft 91 passes through the case 92.

[0196] The rotor 90 includes a magnet 95 and a rotor body. In this embodiment, the rotor 90 is a flat member. The number of magnets 95 may be a plurality of magnets as in this embodiment, or may be one, unlike this embodiment. When the number of magnets 95 is a plurality of magnets, the plurality of magnets 95 are arranged at equal intervals in the circumferential direction of the rotor body. In this embodiment, each magnet 95 is flat and has a planar shape corresponding to the planar shape of the first end face 36 of the third member 30 in each core piece 1. Each magnet 95 may be a convex lens shape having a convex surface toward each stator 8 side. When the number of magnets 95 is one, the shape of the magnet 95 is annular. In one magnet 95, the south pole and the north pole are alternately arranged in the circumferential direction. The rotor body supports the plurality of magnets 95. The rotor body is an annular member. The rotor body is rotatably supported by the rotating shaft 91. The magnets 95 are arranged at equal intervals in the circumferential direction of the rotor body. Each magnet 95 is magnetized in the axial direction of the rotating shaft 91. The magnetization directions of adjacent magnets 95 in the circumferential direction of the rotor body are opposite to each other. The rotating magnetic field generated by the stator 8 causes the magnets 95 to repeatedly attract and repel each core piece 1, thereby rotating the rotor 90.

[0197] The stator 8 is disposed so that the first end face 36 of the third member 30 in each core piece 1 faces the magnet 95 of the rotor 90. When the rotor 90 rotates, the first end face 36 of the third member 30 in each core piece 1 receives magnetic flux from the rotating magnet 95. If the first end face 36 of the third member 30 in each core piece 1 is configured in a convex shape as described above, as shown in FIG. 3, the noise and vibration of the rotating electric machine 9 can be reduced. The reason is as follows. Since the first end face 36 of the third member 30 in each core piece 1 is provided in a convex shape, a sudden change in the magnetic flux of the magnet 95 of the rotor 90 received by each core piece 1 is easily suppressed. Therefore, the cogging torque is easily reduced. Since the cogging torque is small, noise and vibration are unlikely to increase.

[0198] The ratio of the first magnetic resistance of the core piece 1 to the magnetic resistance of the rotating electric machine 9 is, for example, 2% or more. As described above, the magnetic resistance of the first member 10 of the core piece 1 of the first embodiment is smaller than the magnetic resistance of the first member of the conventional core piece. Therefore, the higher the ratio, the more excellent the magnetic characteristics of the rotating electric machine 9 including the core piece 1 are compared to the rotating electric machine including the conventional core piece. The first magnetic resistance is the magnetic resistance of the region of the core piece 1 excluding the second member 20. That is, the first magnetic resistance of the core piece 1 of the first embodiment is the sum of the magnetic resistances of the first member 10 and the third member 30. The first magnetic resistance of the core piece 1 of the second embodiment is the magnetic resistance of the first member 10. When the ratio is 2% or more, the rotating electric machine 9 including the core piece 1 is excellent in magnetic characteristics compared to the rotating electric machine including the conventional core piece. The ratio can further be 2.5% or more, and particularly 3% or more. The upper limit of the ratio is, for example, 30% in practical use. That is, the ratio is 2% or more and 30% or less, further 2.5% or more and 28% or less, and particularly 3% or more and 25% or less.

[0199] The magnetic resistance of the rotating electric machine 9 is the sum of the second magnetic resistance, the third magnetic resistance, and the fourth magnetic resistance. The second magnetic resistance is the sum of the magnetic resistances of the magnets 95 of the rotor 90. The third magnetic resistance is the sum of the magnetic resistances of the air gaps. The fourth magnetic resistance is the sum of the magnetic resistances of the core pieces 1. When a back yoke 98 is provided as in the rotating electric machine 9 of embodiment 6 described later, the magnetic resistance of the rotating electric machine 9 is the sum of the second magnetic resistance, the third magnetic resistance, the fourth magnetic resistance, and the magnetic resistance of the back yoke 98. Here, each magnetic resistance is considered as follows.

[0200] The magnetic resistance of the magnet 95 is the product of the area of ​​the magnet 95 and the thickness of the magnet 95. The area of ​​the magnet 95 is the area of ​​the face of the magnet 95 that faces the core piece 1.

[0201] The magnetic resistance of each air gap is the product of the area of ​​the magnet 95 and the length of the gap. The length of the gap is the length along the axial direction of the stator core 7 between the magnet 95 and the core piece 1.

[0202] The magnetic resistance of each core piece 1 is the sum of the magnetic resistance of the first member 10, the magnetic resistance of the second member 20, and the magnetic resistance of the third member 30. When the third member 30 is not provided, the magnetic resistance of each core piece 1 is the sum of the magnetic resistance of the first member 10 and the magnetic resistance of the second member 20.

[0203] The magnetic resistance of the first member 10 is the product of the area of ​​the first member 10 and the height of the first member 10. The area of ​​the first member 10 is the area of ​​a cross section of the first member 10 perpendicular to the axial direction of the stator core 7.

[0204] The magnetic resistance of the second member 20 is the product of the area of ​​the second member 20 and the magnetic path length of the second member 20. The area of ​​the second member 20 is the area of ​​a cross section of the second member 20 perpendicular to the axial direction of the stator core 7. The magnetic path length of the second member 20 is the arc length between the centers of gravity of the first members 10 adjacent to each other in the circumferential direction when the stator core 7 is viewed in a plan view.

[0205] The magnetic resistance of the third member 30 is the area of ​​the third member 30 and the magnetic path length of the third member 30. The area of ​​the third member 30 is the area of ​​a cross section of the third member 30 perpendicular to the axial direction of the stator core 7. The magnetic path length of the third member 30 is the arc length between the centers of gravity of the first members 10 adjacent to each other in the circumferential direction when the stator core 7 is viewed in a plan view.

[0206] The magnetic resistance of the back yoke 98 is the product of the area of ​​the back yoke 98 and the magnetic path length of the back yoke 98. The area of ​​the back yoke 98 is the area of ​​a cross section of the back yoke 98 perpendicular to the axial direction of the rotating electric machine 9. The magnetic path length of the back yoke 98 is the arc length between the centers of gravity of magnets 95 adjacent to each other in the circumferential direction when the rotor 90 is viewed in a plan view.

[0207] [Action and Effect] The rotating electric machine 9 of this embodiment has excellent magnetic properties since it includes the stator 8 of embodiment 4. Moreover, the rotating electric machine 9 of this embodiment has excellent productivity since it includes the stator 8 of embodiment 4 which has excellent productivity.

[0208] Sixth Embodiment [Rotary Electric Machine] A rotating electric machine 9 according to the sixth embodiment will be described with reference to FIG. 19. The rotating electric machine 9 of this embodiment is an axial gap type rotating electric machine. The rotating electric machine 9 of this embodiment differs from the rotating electric machine 9 of the fifth embodiment mainly in that it is an SS / DR type having two rotors 90 and one stator 8. That is, in the rotating electric machine 9, the rotor 90 and the stator 8 are arranged facing each other in the axial direction. One stator 8 is assembled so as to be sandwiched between the two rotors 90. The following description will focus on the differences from the fifth embodiment. Description of the same configuration as the fifth embodiment will be omitted.

[0209] Each rotor 90 includes a rotor body, a plurality of magnets 95, and a back yoke 98. The rotor body and the plurality of magnets 95 are as in the above-described fifth embodiment. The back yoke 98 is provided between the rotor 90 and the plate 922. The back yoke 98 is a flat plate-shaped member. The back yoke 98 is made of a powder compact similar to the above-described core piece 1, or a laminated steel plate.

[0210] The stator 8 includes a plurality of core pieces 1 arranged in an annular shape, a coil 80 wound around the first member 10 of each core piece 1, and a support member that holds the plurality of core pieces 1. The support member is not shown. The configurations of the second member 20 and the third member 30 of each core piece 1 are the same. That is, the protruding amounts of the first protruding portion 211 and the second protruding portion 212 in the second member 20 and the protruding amounts of the first protruding portion 311 and the second protruding portion 312 in the third member 30 are the same. In addition, the first side surface 24a of the first protruding portion 211 and the second side surface 24b of the second protruding portion 212 in the second member 20 do not have the above-mentioned step. The coil 80 is as in the above-mentioned embodiment 4. The holder holds the plurality of core pieces 1 so that the intervals between the core pieces 1 are equal. This holder prevents the core pieces 1 adjacent to each other in the circumferential direction from contacting each other.

[0211] [Action and Effect] The rotating electric machine 9 of this embodiment has excellent magnetic properties, similar to the rotating electric machine 9 of embodiment 5. Moreover, the rotating electric machine 9 of embodiment 6 has excellent productivity, similar to the rotating electric machine 9 of embodiment 5, since it includes the stator 8 which has excellent productivity.

[0212] The present invention is not limited to these examples, but is intended to include all modifications within the meaning and scope of the claims. For example, the rotating electric machine may include one rotor and one stator. [Explanation of symbols]

[0213] 1 core piece 10 First member 11 peripheral surface, 12 outer peripheral surface, 13 inner peripheral surface 14a first side, 14b second side 141 first parallel plane, 142 second parallel plane, 143 first inclined plane 16 end faces, 18 corners 20 Second member 21 protrusion, 211 first protrusion, 212 second protrusion 22 outer circumferential surface, 23 inner circumferential surface, 24a first side, 24b second side 240 steps 241 first parallel plane, 242 second parallel plane, 243 first inclined plane 244 Protruding part 26 First end face, 27 Second end face, 28 Corner part 30 Third member 31 protrusion, 311 first protrusion, 312 second protrusion 32 outer circumferential surface, 33 inner circumferential surface 34a first side, 34b second side 341 first parallel plane, 342 second parallel plane, 343 first inclined plane 36 first end face, 37 second end face, 38 corner 4 Coated soft magnetic particles, 40 Soft magnetic particles, 41 Insulating coating 5. Mold 50 die, 50h hole 51 First hole 511: first straight section, 512: second straight section, 513: tapered section 52 Second hole 521 first straight section, 522 second straight section, 523 tapered section 53 Third hole 531 first straight section, 532 second straight section, 533 tapered section 54 Upper Punch 541 first upper punch portion, 541e first lower end surface 542 second upper punch portion, 542e second lower end surface 543 third upper punch portion, 543e third lower end surface 55 Lower punch 551 first lower punch portion, 551e first upper end surface 552 second lower punch portion, 552e second upper end surface 553 third lower punch portion, 553e third upper end surface 7 stator core, 8 stator, 80 coil 9 Rotating Electric Machines 90 rotor, 91 rotating shaft, 92 case 921 Cylinder, 922 Plate 93 Bearing, 95 Magnet, 98 Back Yoke E11, E12, E21, E22, E31, E32 extension surface Va, Vb virtual surface, V21 first virtual surface, V22 second virtual surface θ11, θ21, θ31 First tilt angle θ12, θ22, θ32 Second inclination angle H1 first height, H10 second height

Claims

1. A member constituting a core piece that is arranged in an annular manner to construct a stator core of an axial gap type rotating electric machine, The member is composed of a powder compact, The powder compact has a plurality of soft magnetic particles, The soft magnetic particles have a flat shape, In a first cross section of the member along the axial direction and the radial direction of the stator core, the soft magnetic particles have a first average aspect ratio of 1.2 or more; The first average aspect ratio is a ratio L12 / L11 of an average length L11 to an average length L12 in the first cross section, The average length L11 is an average of the lengths of the soft magnetic particles along the radial direction of the stator core, The average length L12 is an average of the lengths of the soft magnetic particles along the axial direction of the stator core, The shape of the member is an outer circumferential surface disposed on an outer circumferential side of the stator core; an inner circumferential surface disposed on an inner circumferential side of the stator core; a first side surface disposed on a first direction side in a circumferential direction of the stator core and connected to the outer circumferential surface and the inner circumferential surface; a second side surface disposed on a second direction side in the circumferential direction of the stator core and connected to the outer circumferential surface and the inner circumferential surface, a length between the first side surface and the second side surface on the outer circumferential surface is longer than a length between the first side surface and the second side surface on the inner circumferential surface, Each of the first side and the second side is A first parallel surface adjacent to the outer circumferential surface; A second parallel surface adjacent to the inner circumferential surface; a first inclined surface connected to the first parallel surface and the second parallel surface; the first parallel surface of the first side surface and the first parallel surface of the second side surface are parallel to each other; the second parallel surface of the first side surface and the second parallel surface of the second side surface are parallel to each other; The first parallel surface of the first side surface and the second parallel surface of the first side surface are parallel to each other. Parts.

2. 2. The member according to claim 1, wherein the powder compact has a relative density of 85% or more.

3. the soft magnetic particles are made of pure iron or an iron-based alloy; 3. The member according to claim 1, wherein the iron-based alloy is an Fe-Si alloy, an Fe-Al alloy, or an Fe-Si-Al alloy.

4. The member according to claim 1 , wherein the soft magnetic particles have an average particle size of 30 μm or more.

5. The member has a first end surface disposed on a first end side of the stator core in the axial direction, A corner between the outer circumferential surface and the first end surface and a corner between the inner circumferential surface and the first end surface are chamfered, The member according to claim 1 , wherein the length of the chamfer is not less than 0.1 mm and not more than 0.5 mm.

6. A stator core of an axial gap type rotating electric machine, A plurality of core pieces arranged in an annular shape; Each of the plurality of core pieces is composed of a member according to any one of claims 1 to 5. Stator core.

7. A stator for an axial gap type rotating electric machine, The stator core according to claim 6 ; A coil; Stator.

8. An axial gap type rotating electric machine having a rotor and a stator, The stator is a stator according to claim 7. Rotating electric motor.

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