Coil, motor, and method for manufacturing coil

Abstract

One embodiment of the present invention is a coil mounted on teeth extending radially outward from the back of an annular iron core surrounding the central axis of a motor. The coil includes: a first winding body formed by winding a flat wire; and a second winding body formed by winding a flat wire, located on the radially outer side of the first winding body and connected to the first winding body. When N is any integer of 1 or more and M is any integer larger than N, the first winding body is a winding body of N layers arranged in two columns arranged radially, and the second winding body is a winding body of M layers arranged in two columns arranged radially.

Description

Technical Field

[0001] The present invention relates to a coil, a motor, and a method for manufacturing a coil. Background Art

[0002] There is known a coil formed by winding a flat wire. For example, Japanese Unexamined Patent Application Publication No. 2004-180396 discloses a coil having a trapezoidal cross-sectional shape of a winding.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication: Japanese Unexamined Patent Application Publication No. 2004-180396 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] When manufacturing a multi-layer coil by winding a flat wire, it is sometimes difficult to arrange the flat wires with high precision. Therefore, the shape of the coil sometimes deforms.

[0008] In view of the above circumstances, one object of the present invention is to provide a coil having a structure capable of suppressing deformation of the shape and a motor having such a coil. Another object of the present invention is to provide a method for manufacturing a coil capable of suppressing deformation of the shape.

[0009] Means for Solving the Problems

[0010] One aspect of the present invention is a coil mounted on a tooth extending radially outward from a ring-shaped core back surrounding the central axis of a motor. The coil includes: a first winding body formed by winding a flat wire; and a second winding body formed by winding a flat wire, located on the radially outer side of the first winding body and connected to the first winding body. When N is any integer of 1 or more and M is any integer larger than N, the first winding body is a winding body of N layers arranged in two rows arranged radially, and the second winding body is a winding body of M layers arranged in two rows arranged radially.

[0011] One aspect of the present invention is a motor having: a rotor that can rotate about a central axis; and a stator that is radially opposed to the rotor with a gap therebetween. The stator includes: a core back that is ring-shaped and surrounds the central axis; teeth that extend radially outward from the core back; and the above-described coil mounted on the teeth.

[0012] One aspect of the present invention is a method for manufacturing a coil, which is mounted on teeth extending radially from the back of an annular iron core surrounding the central axis of a motor. The method for manufacturing the coil includes the following steps: winding a flat wire to form a first winding body; winding a flat wire to form a second winding body; and disposing the second winding body on the other side in the radial direction of the first winding body and connecting the first winding body and the second winding body. When N is any integer of 1 or more and M is any integer larger than N, the first winding body is a winding body of N layers arranged in two columns arranged in the radial direction, and the second winding body is a winding body of M layers arranged in two columns arranged in the radial direction.

[0013] Advantages of the Invention

[0014] According to one aspect of the present invention, deformation of the shape of the coil can be suppressed. Description of the Drawings

[0015] Figure 1 is a cross-sectional view schematically showing the motor of the first embodiment.

[0016] Figure 2 is a cross-sectional view showing a part of the stator of the first embodiment, which is Figure 1 the II-II cross-sectional view in

[0017] Figure 3 is a perspective view showing a part of the coil of the first embodiment.

[0018] Figure 4 is a flowchart showing the process in the method for manufacturing the coil of the first embodiment.

[0019] Figure 5 is a cross-sectional view showing a part of the process in the method for manufacturing the coil of the first embodiment.

[0020] Figure 6 is a cross-sectional view showing another part of the process in the method for manufacturing the coil of the first embodiment.

[0021] Figure 7 is a cross-sectional view showing the coil of the second embodiment. Detailed Description of the Invention

[0022] The Z-axis direction appropriately shown in each figure is the up-down direction with the positive side being the "upper side" and the negative side being the "lower side". The central axis J appropriately shown in each figure is an imaginary line parallel to the Z-axis direction and extending in the up-down direction. In the following description, the axial direction of the central axis J, that is, the direction parallel to the up-down direction, is simply referred to as the "axial direction", the radial direction centered on the central axis J is simply referred to as the "radial direction", and the circumferential direction centered on the central axis J is simply referred to as the "circumferential direction". In addition, in each embodiment, the inner side in the radial direction is one side in the radial direction, and the outer side in the radial direction is the other side in the radial direction.

[0023] In addition, the up-down direction, the upper side, and the lower side are only names used to explain the arrangement relationship of each part, etc., and the actual arrangement relationship, etc. can also be an arrangement relationship other than the arrangement relationship represented by these names.

[0024] <First Embodiment>

[0025] As Figure 1 shown, the motor 1 of the present embodiment is an inner-rotor type motor. The central axis of the motor 1 is the central axis J. The motor 1 includes a housing 2, a rotor 3, a stator 10, a bearing retainer 4, and bearings 5a, 5b. The housing 2 houses the rotor 3, the stator 10, the bearing retainer 4, and the bearings 5a, 5b. The rotor 3 can rotate about the central axis J. The rotor 3 has a shaft 3a and a rotor body 3b.

[0026] The shaft 3a extends in the axial direction along the central axis J. The shaft 3a is, for example, cylindrical and extends in the axial direction centered on the central axis J. The shaft 3a is supported by the bearings 5a, 5b so as to be rotatable about the central axis J. The rotor body 3b is fixed to the outer peripheral surface of the shaft 3a. Although not shown, the rotor body 3b has a rotor core fixed to the outer peripheral surface of the shaft 3a and magnets fixed to the rotor core. The bearing retainer 4 holds the bearing 5b.

[0027] The stator 10 is opposed to the rotor 3 in the radial direction with a gap therebetween. In the present embodiment, the stator 10 is located on the outer side in the radial direction of the rotor 3. As Figure 2 shown, the stator 10 has a stator core 20, a plurality of coils 30, and an insulating member 40. The stator core 20 has an annular core back 21 surrounding the central axis J and a plurality of teeth 22 extending radially inward from the core back 21. The core back 21 is, for example, cylindrical centered on the central axis J.

[0028] The plurality of teeth 22 are arranged at intervals in the circumferential direction. The plurality of teeth 22 are, for example, arranged at equal intervals in the entire circumferential range along the circumferential direction. In the present embodiment, the plurality of teeth 22 are integrally formed with the core back 21. Each tooth 22 is a substantially rectangular parallelepiped shape extending linearly in the radial direction. The circumferential dimension of the tooth 22 is substantially constant over the entire radial direction.

[0029] Alternatively, an umbrella-shaped portion that protrudes toward both circumferential sides may be provided at the end portion on the radially inner side of the tooth 22. Alternatively, the tooth 22 may be a component separate from the back portion 21 of the iron core. In this case, the tooth 22 may be fixed to the back portion 21 of the iron core, for example, by pressing a convex portion provided at the end portion on the radially outer side of the tooth 22 into a concave portion provided on the radially inner surface of the back portion 21 of the iron core.

[0030] A plurality of coils 30 are respectively mounted on the plurality of teeth 22. In the present embodiment, the coils 30 are mounted on the teeth 22 with an insulating member 40 interposed therebetween. Each tooth 22 passes through the inside of each coil 30 in the radial direction. The radially inner end portion of the tooth 22 protrudes more radially inward than the coil 30.

[0031] The coil 30 is formed by winding a flat wire. Therefore, the space factor of the coil 30 can be improved as compared with the case of using a round wire. In the present specification, a "flat wire" refers to a wire having a quadrilateral or substantially quadrilateral cross-sectional shape. In the present specification, the so-called "substantially quadrilateral" includes a rounded quadrilateral in which the corners of the quadrilateral are rounded. Although not shown, in the present embodiment, the flat wire constituting the coil 30 is an enameled wire having an enameled coating on the surface.

[0032] The coil 30 has a pair of axially extending portions 30b that extend axially on both circumferential sides of the tooth 22 on which the coil 30 is mounted. The pair of axially extending portions 30b sandwich the tooth 22 in the circumferential direction. The axially extending portion 30b is formed by bundling a plurality of parts of the flat wire constituting the coil 30. The contour shape of the axially extending portion 30b in a cross section perpendicular to the axis is, for example, a fan shape in which the circumferential dimension becomes smaller toward the radially inner side.

[0033] In the present specification, the "fan shape" includes a shape surrounded by two arcs having the same center of curvature and different radii and two line segments that extend in the radial direction of a circle centered on the center of curvature and connect the ends of the two arcs to each other. In addition, in the present specification, the "fan shape" includes both a strictly fan shape and a substantially fan shape. In the present specification, the "substantially fan shape" includes a shape in which the arc of the fan shape is approximated by a plurality of line segments. In the present embodiment, the contour shape of the axially extending portion 30b in a cross section perpendicular to the axis is a shape surrounded by the above two arcs and two line segments. Although not shown, the center of curvature of the contour shape of the axially extending portion 30b in a cross section perpendicular to the axis is located radially inside the back portion 21 of the iron core and at a position different from the central axis J.

[0034] The coil 30 has a first winding body 31 and a second winding body 32. The first winding body 31 and the second winding body 32 are respectively formed by winding flat wires. In the present embodiment, the first winding body 31 constitutes the radially inner part of the coil 30. In the present embodiment, the second winding body 32 constitutes the radially outer part of the coil 30. That is, the second winding body 32 is located radially outside the first winding body 31.

[0035] The second winding body 32 is connected to the first winding body 31. More specifically, as Figure 3 shown, one end portion 31c of the flat wire constituting the first winding body 31 is connected to one end portion 32c of the flat wire constituting the second winding body 32. Thus, the first winding body 31 and the second winding body 32 are connected in series to form a single coil 30. The method of connecting the one end portion 31c and the one end portion 32c is not particularly limited. The one end portion 31c and the one end portion 32c can be fixed by solder, can be fixed by laser welding, or can be fixed by ultrasonic bonding. In addition, concave portions that engage with each other may be provided at the one end portion 31c and the one end portion 32c respectively.

[0036] In the following description, let N be any integer of 1 or more, and let M be any integer larger than N. At this time, the first winding body 31 is a winding body wound in N layers arranged in two columns along the radial direction. The second winding body 32 is a winding body wound in M layers arranged in two columns along the radial direction. As Figure 2 shown, in the present embodiment, the first winding body 31 is formed by overlapping three layers of windings wound in two columns arranged along the radial direction. That is, in the present embodiment, N is 3, and the first winding body 31 is a three-layer winding body wound in two columns arranged along the radial direction. Thus, the total number of turns of the first winding body 31 is 6.

[0037] In the present embodiment, the second winding body 32 is formed by overlapping four layers of windings wound in two columns arranged along the radial direction. That is, in the present embodiment, M is 4, and the second winding body 32 is a four-layer winding body wound in two columns arranged along the radial direction. Thus, the total number of turns of the second winding body 32 is 8. Therefore, the total number of turns of the coil 30 is 14.

[0038] The first winding body 31 has a pair of first axially extending portions 31b that extend axially on both circumferential sides of the tooth 22 on which the first winding body 31 is mounted. The contour shape of the first axially extending portion 31b in a cross section perpendicular to the axial direction is, for example, a fan shape in which the circumferential dimension becomes smaller toward the radially inner side. More specifically, the contour shape of the first axially extending portion 31b in a cross section perpendicular to the axial direction is a shape surrounded by two arcs and two line segments, similarly to the above-described axially extending portion 30b.

[0039] In the present embodiment, the cross-sectional shape of the portion of the rectangular wire forming the first winding body 31 and constituting the first axially extending portion 31b is a trapezoidal shape in which the circumferential dimension decreases as it approaches the radially inner side. More specifically, the cross-sectional shape of the portion of the rectangular wire forming the first winding body 31 and constituting the first axially extending portion 31b is a trapezoidal shape with rounded corners in which the circumferential dimension decreases as it approaches the radially inner side. In the following description, the portion of the rectangular wire forming the first winding body 31 and constituting the first axially extending portion 31b is referred to as the first coil wire portion 31a.

[0040] Each of the pair of first axially extending portions 31b is formed by bundling a plurality of first coil wire portions 31a. In the present embodiment, each first axially extending portion 31b is formed by bundling six first coil wire portions 31a. More specifically, in the present embodiment, each first axially extending portion 31b is formed by arranging three first coil wire portions 31a in a row in the circumferential direction and arranging two rows in the radial direction. The circumferential dimension of the first coil wire portion 31a forming the row located on the radially outer side of the two rows arranged in the radial direction in the cross-section is larger than the circumferential dimension of the first coil wire portion 31a forming the row on the radially inner side in the cross-section. The radial dimension of the first coil wire portion 31a forming the row on the radially outer side in the cross-section is smaller than the radial dimension of the first coil wire portion 31a forming the row on the radially inner side in the cross-section. The cross-sectional areas of the respective first coil wire portions 31a are the same.

[0041] The second winding body 32 has a pair of second axially extending portions 32b that extend axially along both circumferential sides of the tooth 22 on which the second winding body 32 is mounted. The pair of second axially extending portions 32b are respectively arranged adjacent to the radially outer sides of the pair of first axially extending portions 31b. The first axially extending portion 31b and the second axially extending portion 32b adjacent to each other in the radial direction constitute the axially extending portion 30b of the coil 30. That is, the axially extending portion 30b has the first axially extending portion 31b provided on the first winding body 31 and the second axially extending portion 32b provided on the second winding body 32.

[0042] The contour shape of the second axially extending portion 32b in the cross-section perpendicular to the axis is, for example, a fan shape in which the circumferential dimension decreases as it approaches the radially inner side. More specifically, the contour shape of the second axially extending portion 32b in the cross-section perpendicular to the axis is a shape surrounded by two arcs and two line segments, similar to the above-mentioned axially extending portion 30b.

[0043] In the present embodiment, the cross-sectional shape of the portion of the flat wire constituting the second winding body 32 that forms the second axially extending portion 32b is a trapezoidal shape in which the circumferential dimension decreases as it approaches the radially inner side. More specifically, the cross-sectional shape of the portion of the flat wire constituting the second winding body 32 that forms the second axially extending portion 32b is a trapezoidal shape with rounded corners in which the circumferential dimension decreases as it approaches the radially inner side. In the following description, the portion of the flat wire constituting the second winding body 32 that forms the second axially extending portion 32b is referred to as the second coil wire portion 32a.

[0044] Each of the pair of second axially extending portions 32b is formed by bundling a plurality of second coil wire portions 32a. In the present embodiment, each second axially extending portion 32b is formed by bundling eight second coil wire portions 32a. More specifically, in the present embodiment, each second axially extending portion 32b is formed by arranging four second coil wire portions 32a in a row along the circumferential direction and arranging two rows in the radial direction. The circumferential dimension of the second coil wire portion 32a forming the radially outer row among the two rows arranged in the radial direction is larger than the circumferential dimension of the second coil wire portion 32a forming the radially inner row in the cross-section. The circumferential dimension of the second coil wire portion 32a in the cross-section is smaller than the circumferential dimension of the first coil wire portion 31a in the cross-section.

[0045] The radial dimension of the second coil wire portion 32a forming the radially outer row in the cross-section is smaller than the radial dimension of the second coil wire portion 32a forming the radially inner row in the cross-section. The radial dimension of the second coil wire portion 32a in the cross-section is larger than the radial dimension of the first coil wire portion 31a in the cross-section. The cross-sectional areas of the respective second coil wire portions 32a are the same.

[0046] As Figure 3 shown, one end portion 31c connected to the second winding body 32 is drawn out obliquely upward from one of the pair of first axially extending portions 31b. One end portion 32c connected to the first winding body 31 is drawn out obliquely upward from one of the pair of second axially extending portions 32b. The first axially extending portion 31b from which the end portion 31c is drawn out and the second axially extending portion 32b from which the end portion 32c is drawn out are located on opposite sides in the circumferential direction with the tooth 22 interposed therebetween.

[0047] Although not shown, the cross-sectional shape of the portion of the flat wire constituting the first winding body 31 other than the portion forming the first axially extending portion 31b is, for example, a square with rounded corners. The cross-sectional shape of the portion of the flat wire constituting the second winding body 32 other than the portion forming the second axially extending portion 32b is, for example, a square with rounded corners.

[0048] As Figure 2As shown, the insulating member 40 is, for example, a sheet-like insulating component. The insulating member 40 can be an insulating tape or an insulating paper. In the present embodiment, the insulating member 40 is provided relative to a pair of axially extending portions 30b respectively. The insulating member 40 is wound around a pair of axially extending portions 30b respectively. In a cross-section perpendicular to the axis, the insulating member 40 provided on the axially extending portion 30b surrounds the axially extending portion 30b. Although not shown, the insulating member 40 is provided over substantially the entire axial direction of the axially extending portion 30b.

[0049] As Figure 4 shown, the manufacturing method of the above-described coil 30 includes a first winding process S1, a second winding process S2, a compression process S3, and a connection process S4. As Figure 5 shown, the first winding process S1 is a process of winding a flat wire to form a first winding body 131. The second winding process S2 is a process of winding a flat wire to form a second winding body 132. Either the first winding process S1 or the second winding process S2 can be performed first, or they can be performed simultaneously.

[0050] The first winding body 131 is a winding body before becoming the above-described first winding body 31. In the first winding body 131, the cross-sectional shape of the plurality of first coil wire portions 131a constituting the first axially extending portion 131b is a square with rounded corners. The contour shape of the first axially extending portion 131b in a cross-section perpendicular to the axis is, for example, substantially rectangular. The cross-sectional shape of the flat wire constituting the first winding body 131 is the same in any part. The first winding body 131 is a three-layer winding body wound in two radially arranged rows.

[0051] The second winding body 132 is a winding body before becoming the above-described second winding body 32. In the second winding body 132, the cross-sectional shape of the plurality of second coil wire portions 132a constituting the second axially extending portion 132b is a square with rounded corners. The contour shape of the second axially extending portion 132b in a cross-section perpendicular to the axis is, for example, substantially rectangular. The cross-sectional shape of the flat wire constituting the second winding body 132 is the same in any part. The cross-sectional shape of the flat wire constituting the second winding body 132 is the same as the cross-sectional shape of the flat wire constituting the first winding body 131. The second winding body 132 is a four-layer winding body wound in two radially arranged rows.

[0052] As Figure 6 shown, the compression process S3 is a process of causing the first winding body 131 and the second winding body 132 to be compressed and deformed. As Figure 4As shown, in the present embodiment, the compression process S3 includes a first compression process S3a and a second compression process S3b. The first compression process S3a is a process of compressing and deforming the first winding body 131. The second compression process S3b is a process of compressing and deforming the second winding body 132. In the present embodiment, the first compression process S3a and the second compression process S3b are arranged in front of the connection process S4. In addition, either the first compression process S3a or the second compression process S3b can be carried out first, or they can be carried out simultaneously.

[0053] In the first compression process S3a of the present embodiment, the contour shape of the first axial extension portion 131b in the cross section perpendicular to the axial direction is deformed into a fan shape in which the circumferential dimension becomes smaller toward the radially inner side. Thus, the cross-sectional shape of the portion of the flat wire constituting the first winding body 131 that constitutes the first axial extension portion 131b, that is, the cross-sectional shape of the first coil wire portion 131a, is deformed into a trapezoidal shape in which the circumferential dimension becomes smaller toward the radially inner side. Through the first compression process S3a, the first axial extension portion 131b becomes the first axial extension portion 31b, and the above-mentioned first winding body 31 is produced.

[0054] In the second compression process S3b of the present embodiment, the contour shape of the second axial extension portion 132b in the cross section perpendicular to the axial direction is deformed into a fan shape in which the circumferential dimension becomes smaller toward the radially inner side. Thus, the cross-sectional shape of the portion of the flat wire constituting the second winding body 132 that constitutes the second axial extension portion 132b, that is, the cross-sectional shape of the second coil wire portion 132a, is deformed into a trapezoidal shape in which the circumferential dimension becomes smaller toward the radially inner side. Through the second compression process S3b, the second axial extension portion 132b becomes the second axial extension portion 32b, and the above-mentioned second winding body 32 is produced.

[0055] As described above, in the compression process S3, the contour shape of the first axial extension portion 131b in the cross section perpendicular to the axial direction is deformed into a fan shape in which the circumferential dimension becomes smaller toward the radially inner side, and the contour shape of the second axial extension portion 132b in the cross section perpendicular to the central axis J is deformed into a fan shape in which the circumferential dimension becomes smaller toward the radially inner side.

[0056] In the first compression process S3a and the second compression process S3b, the method of compressing and deforming each winding body is not particularly limited. In the first compression process S3a and the second compression process S3b of the present embodiment, stamping is performed on each axial extension portion using a mold that surrounds each axial extension portion of each winding body, so that each winding body is compressed and deformed.

[0057] The connecting step S4 is a step of arranging the second winding body 32 on the radially outer side of the first winding body 31 and connecting the first winding body 31 and the second winding body 32. In the connecting step S4 of the present embodiment, one end portion 31c of the first winding body 31 is connected to one end portion 32c of the second winding body 32. As described above, the method of connecting the one end portion 31c and the one end portion 32c is not particularly limited. Through the above steps, the coil 30 is manufactured.

[0058] According to the present embodiment, the coil 30 has a first winding body 31 and a second winding body 32 connected to the first winding body 31. When N is any integer of 1 or more and M is any integer larger than N, the first winding body 31 is a winding body of N layers wound in two columns arranged radially, and the second winding body 32 is a winding body of M layers wound in two columns arranged radially. When the rectangular wire is wound in two columns, it is easier to wind the rectangular wires accurately with respect to each other than when the rectangular wire is wound in three or more columns. Therefore, by connecting a plurality of winding bodies each wound in two columns, it is possible to easily manufacture the coil 30 in which the rectangular wires are accurately arranged in four or more columns. Thereby, deformation of the shape of the coil 30 can be suppressed.

[0059] In addition, M is any integer larger than N. Therefore, the number of layers of the second winding body 32 located on the radially outer side of the first winding body 31 is larger than the number of layers of the first winding body 31. Here, when the motor 1 is an inner rotor type motor, the interval between the adjacent teeth 22 in the circumferential direction becomes larger toward the radially outer side. Therefore, by making the number of layers of the second winding body 32 located on the radially outer side of the first winding body 31 larger than the number of layers of the first winding body 31, more windings can be arranged with good space efficiency between the teeth 22. Thereby, the total number of turns of the coil 30 can be appropriately increased.

[0060] In addition, for example, when simply winding the rectangular wire to manufacture a multi-layer wound coil, the total number of turns of the coil is the number obtained by multiplying the number of arrangements by the number of layers. Therefore, for example, when at least one of the number of arrangements and the number of layers is limited, there may be a limitation on the total number of turns of the coil that can be adopted. In contrast, according to the present embodiment, since the number of layers of the first winding body 31 and the number of layers of the second winding body 32 are different from each other, it is easy to adjust the total number of turns of the coil 30 by respectively adjusting the number of layers of each winding body. Therefore, the degree of freedom of the total number of turns of the coil 30 that can be adopted can be increased. In the present embodiment, for example, the total number of turns of the coil 30 can be any even number of 6 or more.

[0061] In addition, according to the present embodiment, the contour shape of the axial extension portion 30b in the cross-section perpendicular to the axis is a fan shape in which the circumferential dimension becomes smaller as it approaches the radially inner side. Therefore, the coil 30 can be appropriately filled and arranged between the teeth 22 adjacent in the circumferential direction. As a result, it is easy to further increase the space factor of the coil 30.

[0062] In addition, for example, in a conventional multi-layer wound coil, when the contour shape of the axial extension portion is the above-described fan shape, the cross-sectional shape of the coil wire portion located more radially inward has a smaller circumferential dimension and a larger radial dimension. On the other hand, the cross-sectional shape of the coil wire portion located more radially outward has a larger circumferential dimension and a smaller radial dimension. As a result, the cross-sectional shape of at least a part of the coil wire portion is likely to become a flat shape. In this case, the eddy current loss of the coil is likely to increase. In addition, when deforming a flat wire having a substantially square cross-sectional shape so that the cross-sectional shape of the flat wire becomes a flat shape, the amount of deformation of the flat wire is likely to increase. Therefore, when deforming the flat wire, the enamel coating provided on the surface may be broken. In addition, the deformation of each coil wire portion constituting the axial extension portion is likely to become uneven.

[0063] In contrast, according to the present embodiment, the number of layers of the second winding body 32 located radially outside the first winding body 31 is larger than the number of layers of the first winding body 31. Therefore, the number of layers of the second winding body 32 constituting the radially outer portion of the axial extension portion 30b can be made relatively large, and the number of layers of the first winding body 31 constituting the radially inner portion of the axial extension portion 30b can be made relatively small. As a result, even if the contour shape of the axial extension portion 30b is deformed into a fan shape, the amount of deformation of each coil wire portion constituting the axial extension portion 30b can be reduced. Therefore, it is possible to suppress the cross-sectional shape of each coil wire portion from becoming flat. Therefore, it is possible to suppress an increase in the eddy current loss of the coil 30. In addition, it is possible to suppress the enamel coating provided on the surface of the flat wire from being broken. In addition, it is possible to suppress the deformation of each coil wire portion constituting the axial extension portion 30b from becoming uneven.

[0064] In addition, for example, when simply arranging and winding flat wires to manufacture a multi-layer wound coil, depending on the number of layers and the like, since the amount of deformation of the flat wire increases as described above, it is sometimes difficult to compress and deform the contour shape of the axial extension portion into a fan shape. Therefore, when the contour shape of the axial extension portion is a fan shape, restrictions are likely to occur in terms of the number of layers and the like, and restrictions may occur in the total number of turns of the coil that can be used. In contrast, according to the present embodiment, as described above, it is possible to make the contour shape of the axial extension portion a fan shape while suppressing the amount of deformation of each coil wire portion. Therefore, it is possible to suppress restrictions on the total number of turns of the coil 30 that can be used, and it is easy to adopt the desired total number of turns of the coil 30 within the range of even numbers of 6 or more.

[0065] Further, according to the present embodiment, the first compression process S3a and the second compression process S3b are provided before the connection process S4. Therefore, after the first winding body 131 and the second winding body 132 are respectively deformed to produce the first winding body 31 and the second winding body 32, the first winding body 31 and the second winding body 32 can be connected. Thus, compared with the case where the first winding body 131 and the second winding body 132 are joined and then compressed and deformed collectively, each winding body can be easily compressed and deformed.

[0066] <Second Embodiment>

[0067] As Figure 7 shown, the coil 230 of the present embodiment further includes a third winding body 233. The third winding body 233 is formed by winding a flat wire. The third winding body 233 is located radially outside the second winding body 32. The third winding body 233 is connected to the second winding body 32. The connection method of the second winding body 32 and the third winding body 233 can adopt the same method as the connection method of the first winding body 31 and the second winding body 32.

[0068] In the following description, let L be any integer greater than M. At this time, the third winding body 233 is a winding body formed by arranging and winding L layers in two columns arranged radially. In the present embodiment, the third winding body 233 is formed by overlapping five layers of windings arranged and wound in two columns arranged radially. That is, in the present embodiment, L is 5, and the third winding body 233 is a winding body formed by arranging and winding five layers in two columns arranged radially. Thus, the total number of turns of the third winding body 233 is 10.

[0069] The third winding body 233 has a pair of third axially extending portions 233b that axially extend on both circumferential sides of the tooth 22 on which the third winding body 233 is mounted. The pair of third axially extending portions 233b are arranged adjacent to the radially outer sides of the pair of second axially extending portions 32b. The contour shape of the third axially extending portion 233b in a cross section perpendicular to the axial direction is, for example, a fan shape in which the circumferential dimension becomes smaller toward the radially inner side. More specifically, the contour shape of the third axially extending portion 233b in a cross section perpendicular to the axial direction is the same as that of the above-mentioned axially extending portion 30b and is a shape surrounded by two arcs and two line segments.

[0070] In the present embodiment, the cross-sectional shape of the portion of the rectangular wire forming the third winding body 233 and constituting the third axially extending portion 233b is a trapezoidal shape in which the circumferential dimension becomes smaller as it approaches the radially inner side. More specifically, the cross-sectional shape of the portion of the rectangular wire forming the third winding body 233 and constituting the third axially extending portion 233b is a trapezoidal shape with rounded corners in which the circumferential dimension becomes smaller as it approaches the radially inner side. In the following description, the portion of the rectangular wire forming the third winding body 233 and constituting the third axially extending portion 233b is referred to as the third coil wire portion 233a.

[0071] Each of the pair of third axially extending portions 233b is formed by bundling a plurality of third coil wire portions 233a. In the present embodiment, each third axially extending portion 233b is formed by bundling 10 third coil wire portions 233a. More specifically, in the present embodiment, each third axially extending portion 233b is formed by arranging two rows in the radial direction of a column formed by arranging five third coil wire portions 233a in the circumferential direction. The circumferential dimension in the cross-section of the third coil wire portion 233a forming the radially outer row of the two rows arranged in the radial direction is larger than the circumferential dimension in the cross-section of the third coil wire portion 233a forming the radially inner row. The circumferential dimension in the cross-section of the third coil wire portion 233a is smaller than the circumferential dimension in the cross-section of the second coil wire portion 32a.

[0072] The radial dimension in the cross-section of the third coil wire portion 233a forming the radially outer row is smaller than the radial dimension in the cross-section of the third coil wire portion 233a forming the radially inner row. The radial dimension in the cross-section of the third coil wire portion 233a is larger than the radial dimension in the cross-section of the second coil wire portion 32a. The cross-sectional areas of the respective third coil wire portions 233a are the same.

[0073] Although not shown, the cross-sectional shape of the portion of the rectangular wire forming the third winding body 233 other than the portion constituting the third axially extending portion 233b is, for example, a square with rounded corners. The other structure of the coil 230 is the same as the other structure of the coil 30 of the first embodiment.

[0074] According to the present embodiment, since the coil 230 is composed of three winding bodies, it is possible to increase the total number of turns of the coil 230 while suppressing deformation of the shape of the coil 230 by arranging each winding with high precision.

[0075] The present invention is not limited to the above-described embodiments, and other structures may be adopted within the scope of the technical idea of the present invention. N only needs to be an integer of 1 or more, and there is no particular limitation. M only needs to be an integer larger than N, and there is no particular limitation. L only needs to be an integer larger than M, and there is no particular limitation. For example, N may be 1, M may be 2, and L may be 3. That is, the first winding body may be a single-layer winding body, the second winding body may be a two-layer winding body, and the third winding body may be a three-layer winding body. In addition, M may be 2 or more larger than N, and L may be 2 or more larger than M. N, M, and L are preferably 10 or less, for example. This is to facilitate winding the flat wire to form each winding body and to facilitate compression deformation of each winding body. In addition, M is preferably 3 times or less of N, for example. Thus, when the second winding body is compressed and deformed, it is possible to suppress the cross-sectional shape of the coil wire portion constituting the second axially extending portion from becoming more flattened. The contour shape of the axially extending portion in the cross-section perpendicular to the axis may not be a fan shape. The cross-sectional shape of the coil wire portion constituting the axially extending portion may not be a trapezoidal shape.

[0076] The process of compressing and deforming the first winding body and the process of compressing and deforming the second winding body may be provided after the process of connecting the first winding body and the second winding body. The process of compressing and deforming the first winding body and the second winding body may not be provided.

[0077] The motor using the coil of the present invention is not particularly limited. The motor using the coil of the present invention may also be an outer rotor type motor. In this case, the radially outer side corresponds to one side in the radial direction, and the radially inner side corresponds to the other side in the radial direction. As described above, the structures described in this specification may be appropriately combined within a range where they do not conflict with each other.

Claims

1. A coil is mounted on teeth extending radially from the back of an annular iron core surrounding the central axis of a motor, wherein, the coil has: a first winding body formed by winding a flat wire; and a second winding body formed by winding a flat wire, located on the other side in the radial direction of the first winding body and connected to the first winding body, when N is any integer of 1 or more and M is any integer larger than N, the first winding body is a winding body of N layers arranged and wound in two columns arranged in the radial direction, the second winding body is a winding body of M layers arranged and wound in two columns arranged in the radial direction, the first winding body has a pair of first axially extending portions extending axially along the central axis on both circumferential sides of the teeth, the second winding body has a pair of second axially extending portions extending axially along the central axis on both circumferential sides of the teeth, the pair of second axially extending portions are respectively arranged adjacent to the other side in the radial direction of the pair of first axially extending portions, the pair of axially extending portions are formed by the pair of first axially extending portions and the pair of second axially extending portions and extend axially along the central axis on both circumferential sides of the teeth, the contour shape of the axially extending portion in a cross section perpendicular to the axial direction of the central axis is a fan shape in which the circumferential dimension becomes smaller toward the radial side, the circumferential dimension in the cross section of the portion of the flat wire constituting the second axially extending portion in the second winding body is smaller than the circumferential dimension in the cross section of the portion of the flat wire constituting the first axially extending portion in the first winding body.

2. The coil according to claim 1, wherein, the coil further has a third winding body formed by winding a flat wire, the third winding body is located on the other side in the radial direction of the second winding body and connected to the second winding body, when L is any integer larger than M, the third winding body is a winding body of L layers arranged and wound in two columns arranged in the radial direction.

3. A motor having: a rotor capable of rotating about a central axis; and a stator opposed to the rotor in the radial direction with a gap therebetween, the stator has: a back iron core in an annular shape surrounding the central axis; teeth extending radially from the back iron core; and the coil according to claim 1 or 2 mounted on the teeth.

4. A method for manufacturing a coil, the coil being mounted on teeth extending radially from the back of an annular iron core surrounding the central axis of a motor, wherein, the method for manufacturing the coil includes the following steps: winding a flat wire to produce a first winding body; winding a flat wire to produce a second winding body; compressing and deforming the first winding body and the second winding body; and arranging the second winding body on the other side in the radial direction of the first winding body and connecting the first winding body and the second winding body, when N is any integer of 1 or more and M is any integer larger than N, the first winding body is a winding body of N layers arranged and wound in two columns arranged in the radial direction, the second winding body is a winding body of M layers arranged and wound in two columns arranged in the radial direction, The first winding body has a pair of first axially extending portions that axially extend along the central axis on both circumferential sides of the tooth. The second winding body has a pair of second axially extending portions that axially extend along the central axis on both circumferential sides of the tooth. The pair of second axially extending portions are respectively disposed adjacent to the radially other side of the pair of first axially extending portions. A pair of axially extending portions that axially extend along the central axis on both circumferential sides of the tooth are formed by the pair of first axially extending portions and the pair of second axially extending portions. The contour shape of the axially extending portion in a cross section perpendicular to the axial direction of the central axis is a fan shape in which the circumferential dimension becomes smaller as it approaches the radially inner side. In the process of compressing and deforming the first winding body and the second winding body, the contour shape of the first axially extending portion in a cross section perpendicular to the axial direction of the central axis is deformed into a fan shape in which the circumferential dimension becomes smaller as it approaches the radially inner side, and the contour shape of the second axially extending portion in a cross section perpendicular to the central axis is deformed into a fan shape in which the circumferential dimension becomes smaller as it approaches the radially inner side. The circumferential dimension in the cross section of the portion of the rectangular wire forming the second axially extending portion in the second winding body is smaller than the circumferential dimension in the cross section of the portion of the rectangular wire forming the first axially extending portion in the first winding body.

5. The method for manufacturing a coil according to claim 4, wherein the process of compressing and deforming the first winding body and the second winding body includes the following processes: compressing and deforming the first winding body; and compressing and deforming the second winding body, the process of compressing and deforming the first winding body and the process of compressing and deforming the second winding body are arranged prior to the process of connecting the first winding body and the second winding body.

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