Edgewise coil

Abstract

Provided is an edgewise coil that is made compact in the axial direction. The edgewise coil (1) comprises a spiral rectangular wire (2) that has a straight part (3) and an edgewise bent corner part (4). The corner part (4) includes an arc-shaped inner peripheral edge part (41). The inner peripheral edge part (41) has a surface (410) that has a pressing mark. The conductor density of the inner peripheral edge part (41) is higher than the conductor density of a portion of the corner part (4) excluding the inner peripheral edge part (41). Thus, the edgewise coil can easily be made compact in the axial direction.

Description

Edgewise Coil

[0001] The present disclosure relates to edgewise coils.

[0002] It has been proposed to form a spiral edgewise coil by edgewise bending a rectangular wire (see, for example, Patent Document 1). The edgewise coil formed by the above method is suitable for use as a component of, for example, a motor stator.

[0003] Japanese Patent Application Laid-Open No. 2020-178457

[0004] It is desirable that the edgewise coil described above be made compact in the axial direction. Making the edgewise coil compact in the axial direction contributes to making a motor including the edgewise coil more compact, for example.

[0005] The problem to be solved by the present disclosure is to provide an edgewise coil that is compacted in the axial direction.

[0006] An edgewise coil according to one embodiment of the present disclosure is made of a spiral flat wire having a straight portion and an edgewise bent corner portion. The corner portion includes an arc-shaped inner peripheral edge portion. The inner peripheral edge portion has a surface with pressure marks. The conductor density of the inner peripheral edge portion is higher than the conductor density of the corner portion excluding the inner peripheral edge portion.

[0007] The present disclosure has an advantage of being able to provide an edgewise coil that is compact in the axial direction.

[0008] FIG. 1 is a plan view of a motor using an edgewise coil according to one embodiment. FIG. 2 is a view of the edgewise coil according to one embodiment as viewed from the axial direction. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is an enlarged perspective view of a corner of the edgewise coil according to one embodiment. FIG. 5 is a cross-sectional view of a corner of the edgewise coil according to one embodiment. FIG. 6 is a schematic view showing a method for manufacturing the edgewise coil according to one embodiment. FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 6. FIG. 8 is a schematic cross-sectional view for explaining the method for manufacturing the edgewise coil according to one embodiment.

[0009] 1. One Embodiment An edgewise coil according to an embodiment of the present disclosure will be described with reference to the accompanying drawings. However, the embodiment described below is merely one of various embodiments of the present disclosure, and various modifications are possible depending on the design, etc., as long as the object of the present disclosure can be achieved. Furthermore, each figure showing the following embodiment is a schematic diagram for explaining the technical concept of the present disclosure, and the size and thickness of each component in the figure, as well as their respective ratios, do not necessarily reflect the actual dimensional ratios.

[0010] 1 is a plan view of a motor 9 using an edgewise coil 1 (see FIG. 2 described later) according to one embodiment. In this embodiment, the edgewise coil 1 is used as a winding 934 of the motor 9 shown in FIG.

[0011] 1 includes a rotor 92 and a stator 93. As an example, the motor 9 is an inner rotor brushless motor in which the rotor 92 is disposed inside the stator 93. The motor 9 is driven by, for example, three-phase AC current (specifically, U-phase, V-phase, and W-phase) that are 120 degrees out of phase with each other.

[0012] The motor 9 preferably further includes a casing (not shown) that houses the rotor 92 and the stator 93 .

[0013] (Rotor) The rotor 92 includes a cylindrical rotating shaft 921 whose center of rotation is the axis C9, a rotor yoke 922 coupled to the rotating shaft 921, and a plurality of magnets 923. The rotor yoke 922 is a cylindrical member having an outer peripheral surface. The plurality of magnets 923 are arranged on the outer surface of the rotor yoke 922. The plurality of magnets 923 are positioned in a line in the circumferential direction of the rotor yoke 922.

[0014] The rotor yoke 922 is formed, for example, by stacking a plurality of non-oriented magnetic steel plates in the axial direction of the rotor 92. The rotor yoke 922 may be formed of iron, silicon steel, permalloy, ferrite, or the like.

[0015] The rotating shaft 921 is inserted into a central hole of the rotor yoke 922. The rotating shaft 921 and the rotor yoke 922 are fixed to each other. The rotor yoke 922 is configured to be rotatable around the axis C9 together with the rotating shaft 921.

[0016] In one embodiment of the motor 9, the rotor 92 is a surface magnet type rotor. A plurality of magnets 923 are attached to the outer surface of the rotor yoke 922 so as to be arranged at equal intervals in the circumferential direction of the rotor 92. In one embodiment of the motor 9, for example, ten magnets 923 are attached at equal intervals to the outer peripheral surface of the rotor yoke 922.

[0017] Each of the plurality of magnets 923 is a permanent magnet such as a neodymium magnet having a rectangular parallelepiped shape. The plurality of magnets 923 are arranged on the outer surface of the rotor yoke 922 so that their magnetic poles are arranged alternately in the circumferential direction of the rotor 92.

[0018] It should be noted that the rotor 92 does not necessarily have to be a surface magnet type rotor, and for example, the rotor 92 may be an embedded magnet type rotor.

[0019] (Stator) The stator 93 includes a cylindrical stator yoke 932 , a plurality of teeth 933 , and a plurality of windings 934 .

[0020] The stator 93 is disposed concentrically with the rotor 92. The stator 93 has a radial direction, a circumferential direction, and an axial direction. When the stator 93 is disposed concentrically with the rotor 92, the radial direction of the stator 93 coincides with the radial direction of the rotor 92, the circumferential direction of the stator 93 coincides with the circumferential direction of the rotor 92, and the axial direction of the stator 93 coincides with the axial direction of the rotor 92.

[0021] The teeth 933 protrude radially inward (i.e., toward the rotor 92) from multiple positions spaced apart from one another in the circumferential direction on the inner peripheral surface of the stator yoke 932. In the motor 9 of one embodiment, the teeth 933 protrude toward the rotor 92 so as to be arranged at equal intervals in the circumferential direction of the stator 93.

[0022] Each of the plurality of teeth 933 is fixed to the stator yoke 932, for example, by fitting a portion of the tooth 933 into a groove provided in the stator yoke 932. Each of the plurality of teeth 933 faces the rotor yoke 922 in the radial direction of the stator 93, with a gap interposed between them.

[0023] The plurality of windings 934 are wound spirally around the plurality of teeth 933, respectively. Each winding 934 is made up of an edgewise coil 1 as shown in FIG. 2 and other drawings, which will be described below. The edgewise coil 1 is wound in multiple layers along the outer circumferential surface of the corresponding tooth 933. The edgewise coil 1 is wound around the corresponding tooth 933 via an insulating insulator.

[0024] In one embodiment of the motor 9, 12 teeth 933 are arranged at equal intervals on the inner circumferential surface of the stator yoke 932, and an edgewise coil 1 is wound around each of the 12 teeth 933. The 12 edgewise coils 1 are divided into three groups corresponding to each of the three phases. Each group includes four edgewise coils 1 arranged at equal intervals in the circumferential direction of the rotor yoke 922.

[0025] In one embodiment, the axial direction of the rotor 92 coincides with the direction in which the rotation shaft 921 extends, in other words, the direction in which the axis C9 of the rotation shaft 921 extends. The radial direction of the rotor 92 is perpendicular to the axial direction of the rotor 92. The rotor yoke 922 is rotatable in the circumferential direction of the rotor 92 around the axis C9 of the rotation shaft 921. The axial direction of the stator 93 coincides with the direction in which the axis C9 of the rotation shaft 921 extends. The radial direction of the stator 93 is perpendicular to the axial direction of the stator 93. The stator yoke 932 is endlessly continuous in the circumferential direction of the stator 93.

[0026] The term orthogonal used in this disclosure is not limited to a state in which the angle between two objects is exactly 90 degrees, but also includes a state in which the angle between two objects is within an error range centered on 90 degrees (for example, within a range of 80 degrees to 100 degrees).

[0027] The stator yoke 932 is formed, for example, by stacking multiple non-oriented magnetic steel plates in the axial direction of the stator 93. The stator yoke 932 is disposed concentrically with the rotor 92. In other words, the central axis of the cylindrical stator yoke 932 coincides with the axis C9 of the rotating shaft 921 of the rotor 92.

[0028] (Details of Edgewise Coil) Fig. 2 is a view of an edgewise coil 1 according to one embodiment as seen from the axial direction. Fig. 3 is a cross-sectional view of the edgewise coil 1 shown in Fig. 2 taken along line III-III. As shown in Figs. 2 and 3, the edgewise coil 1 according to one embodiment is made of a rectangular wire 2 formed into a spiral shape. The rectangular wire 2 is a strip-shaped electric wire having a flat cross-sectional shape. The rectangular wire 2 is made of a material such as copper or aluminum. The copper used here is preferably oxygen-free copper.

[0029] As shown in Figures 1 and 3, the spirally formed rectangular wire 2 (i.e., the edgewise coil 1) has a central axis C2. Hereinafter, the direction in which the central axis C2 extends will be referred to as the axial direction of the edgewise coil 1. The rectangular wire 2 has a spiral shape wound in multiple layers around the central axis C2. The direction in which the central axis C2 extends is the up-and-down direction in Figure 3.

[0030] The spirally formed rectangular wire 2 has a plurality of straight portions 3 and a plurality of angular portions 4 formed by edgewise bending (see FIG. 2). In the spiral rectangular wire 2, the straight portions 3 and the angular portions 4 are alternately positioned. Edgewise bending here refers to a bending method in which the flat rectangular wire 2 is bent so that the radius of curvature of one side is small, as shown in FIG. 2.

[0031] Each of the multiple corners 4 connects two adjacent straight line portions 3 among the multiple straight line portions 3 to form an L-shape. Hereinafter, of the two straight line portions 3 connected via one corner 4, one straight line portion 3 will be referred to as a first straight line portion 31, and the other straight line portion 3 will be referred to as a second straight line portion 32. The direction in which the first straight line portion 31 extends from one corner 4 and the direction in which the second straight line portion 32 extends from this one corner 4 are perpendicular to each other.

[0032] When the spiral flat wire 2 is viewed along its central axis C2, the flat wire 2 has a rectangular frame-like outer shape with multiple straight portions 3 and multiple corners 4 (see Figure 2). When the flat wire 2 is viewed along its central axis C2, the shape of the inner peripheral edge of the flat wire 2 is rectangular, and the shape of the outer peripheral edge of the flat wire 2 is a rectangle that is one size larger than the inner peripheral edge of the flat wire 2.

[0033] The term "rectangular" used in the present disclosure is not limited to a rectangular shape in the strict sense, but also includes an approximately rectangular shape. For example, an approximately rectangular shape in which all or some of the four corners are not strictly right angles is also included in the rectangular shape in the present disclosure.

[0034] The flat wire 2 has a spiral shape in which the outer diameter gradually increases along its central axis C2. In other words, the edgewise coil 1 of one embodiment, which is made up of the spiral flat wire 2, has a spiral shape in which the outer diameter gradually increases along the axial direction. In the edgewise coil 1 of one embodiment, the inner diameter is uniform in the axial direction.

[0035] The flat wire 2 has a plurality of layers 21 that overlap each other in the direction of extension of its central axis C2. In other words, the edgewise coil 1 of one embodiment, which is made up of the spiral flat wire 2, has a plurality of layers 21 that overlap each other in the axial direction.

[0036] The width of the flat wire 2 gradually increases along its longitudinal direction. Therefore, the widths of the multiple layers 21 overlapping each other in the axial direction of the edgewise coil 1 (i.e., the direction in which the central axis C2 extends) are gradually increased toward the layers 21 located on one side of the axial direction of the edgewise coil 1 (lower in FIG. 3 ), and gradually decreased toward the layers 21 located on the other side of the axial direction of the edgewise coil 1 (upper in FIG. 3 ). Of the multiple layers 21 of the flat wire 2, one layer 21 is narrower than all the layers 21 located on that side of the axial direction of the edgewise coil 1. The width of a layer 21 of the flat wire 2 is the dimension between the inner and outer peripheries of that layer 21.

[0037] (Corner Portions) The plurality of corner portions 4 of the spirally formed rectangular wire 2 have the following common structure.

[0038] Figure 4 is an enlarged perspective view of a corner 4 of an edgewise coil 1 according to one embodiment. As shown in Figure 4, the corner 4 of the spiral flat wire 2 includes an inner peripheral edge 41 that is an arc and an outer peripheral edge 45 that is a slightly larger arc. The inner peripheral edge 41 and the outer peripheral edge 45 of the corner 4 are spaced apart from each other in the radial direction of the corner 4. The inner peripheral edge 41 of the corner 4 is located radially inward of the outer peripheral edge 45 of the corner 4.

[0039] The inner peripheral edge 41 of the corner 4 of the rectangular wire 2 has a surface 410 with pressure marks. Pressure marks are formed on the surface 410 of the corner 4 due to plastic deformation of the rectangular wire 2. The surface 410 with processing marks has a smaller surface roughness than the surface of the rest of the corner 4 (i.e., the surface without processing marks). In other words, the surface roughness of the inner peripheral edge 41 of the corner 4 of the rectangular wire 2 is smaller than the surface roughness of the part of the corner 4 excluding the inner peripheral edge 41. The arithmetic mean roughness is preferably used as a parameter to represent the surface roughness here. The arithmetic mean roughness of the surface 410 with processing marks is smaller than the arithmetic mean roughness of the surface of the rest of the corner 4. The surface 410 with smaller surface roughness than the rest of the corner 4 is easily visible because it scatters reflected light less than the rest of the corner 4 when irradiated with light.

[0040] The corners 4 of the flat wire 2 have surfaces 410 with press marks on both sides in the thickness direction of the flat wire 2. In other words, the corners 4 of the flat wire 2 have surfaces 410 with press marks on both sides in the direction in which the central axis C2 of the flat wire 2 extends. The corners 4 of the flat wire 2 that make up the spiral edgewise coil 1 have surfaces 410 with press marks on both sides in the axial direction of the edgewise coil 1. The surfaces 410 on both sides face opposite each other in the axial direction.

[0041] At the corner 4 of the rectangular wire 2, there are pressure marks on the surface 410 on both sides of the inner peripheral edge 41, and plastic deformation has occurred at the inner peripheral edge 41. Therefore, the conductor density at the inner peripheral edge 41 of the corner 4 is higher than the conductor density of the portion of the corner 4 excluding the inner peripheral edge 41. The conductor density at the inner peripheral edge 41 of the corner 4 is higher than the conductor density of the portion of the corner 4 where no pressure marks are formed.

[0042] The thickness T1 (see FIG. 8 described later) of the inner peripheral edge 41 of the corner 4 of the rectangular wire 2 is the same as the thickness of the portion of the rectangular wire 2 excluding the corners 4. In other words, the thickness T1 of the inner peripheral edge 41 of the corner 4 of the rectangular wire 2 is the same as the thickness of the straight portions 3 of the rectangular wire 2. The thickness T1 of the inner peripheral edge 41 of the corner 4 of the rectangular wire 2 is the same as the thickness of the first straight portion 31 extending from this corner 4, and is also the same as the thickness of the second straight portion 32 extending from this corner 4.

[0043] The radius of curvature of the inner peripheral edge 41 of the corner 4 of the rectangular wire 2 is preferably 35% or less of the maximum plate width of the rectangular wire 2. The radius of curvature of the inner peripheral edge 41 of the corner 4 is greater than 0% of the maximum plate width of the rectangular wire 2. In other words, the side of the inner peripheral edge 41 of the corner 4 is a curved surface, more specifically, a part of a cylindrical surface. In addition, the radius of curvature of the inner peripheral edge 41 of the corner 4 of the rectangular wire 2 is also preferably 35% or less of the maximum width of each of the two linear portions 3 (i.e., the first linear portion 31 and the second linear portion 32) that are continuous through this corner 4.

[0044] The corners 4 of the rectangular wire 2 are preferably bent edgewise after annealing. That is, after annealing the straight rectangular wire 2 that constitutes the base material of the edgewise coil 1, the corresponding portions of the straight rectangular wire 2 are preferably bent edgewise so as to form an arc.

[0045] (Manufacturing Method) A manufacturing method for the edgewise coil 1 of one embodiment (hereinafter simply referred to as "manufacturing method of one embodiment") will be described below with reference to Fig. 6 to Fig. 8. Fig. 6 is a schematic diagram showing a manufacturing method for the edgewise coil 1 of one embodiment. Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 6. Fig. 8 is a schematic cross-sectional view for explaining the manufacturing method for the edgewise coil 1 of one embodiment.

[0046] The manufacturing method of one embodiment includes an annealing step and a bending step. The annealing step is a step of annealing the base material 8 of the edgewise coil 1, and the bending step is a step of edgewise bending the base material 8 after the annealing step.

[0047] The base material 8 of the edgewise coil 1 is the rectangular wire 2 before being edgewise bent. In the bending process, as shown in Figures 6 and 7 , a pair of jigs 51, 52 are placed on both sides of the thickness direction of the base material 8 at locations corresponding to the corners 4 of the base material 8 of the edgewise coil 1, and the base material 8 is edgewise bent at locations corresponding to the corners 4. In the bending process, the jigs 51, 52 are pressed against the base material 8 in two directions perpendicular to the direction in which the base material 8 is bent by edgewise bending. The direction in which the jig 51 is pressed against the base material 8 and the direction in which the jig 52 is pressed against the base material 8 are opposite to each other.

[0048] The corner portion 4 of the edgewise coil 1 formed through the above-described annealing and bending processes includes an arc-shaped inner peripheral edge portion 41 (see FIG. 4 ). A pressure mark is formed on the surface 410 of this inner peripheral edge portion 41 due to plastic deformation caused by contact with the jig 51 (52). That is, a pressure mark is formed on one of the surfaces 410 on both sides of the inner peripheral edge portion 41 due to plastic deformation caused by contact with the jig 51, and a pressure mark is formed on the other of the surfaces 410 on both sides of the inner peripheral edge portion 41 due to plastic deformation caused by contact with the jig 52 (see FIG. 8 ).

[0049] 8 , the thickness T1 of the inner peripheral edge 41 is uniform at the corner 4 that has been edgewise bent while being sandwiched between jigs 51 and 52. The thickness T1 of the inner peripheral edge 41 is the distance between the surfaces 410 on both sides of the inner peripheral edge 41. In other words, the thickness T1 of the inner peripheral edge 41 is the distance between the processing marks on both sides of the inner peripheral edge 41.

[0050] The thickness T1 of the inner peripheral edge 41 corresponds to the distance between the jigs 51 and 52. The thickness T1 of the inner peripheral edge 41 is, for example, equal to the distance between the jigs 51 and 52. The portion of the corner 4 excluding the inner peripheral edge 41 is formed so that the thickness gradually decreases toward the outer peripheral edge. The thickness T2 of the outer peripheral edge of the corner 4 is smaller than the thickness T1 of the inner peripheral edge 41 of the corner 4 (see FIG. 8 ).

[0051] 5 is a cross-sectional view of a corner 4 of an edgewise coil 1 according to one embodiment. Because the thickness T2 of the outer peripheral edge of the corner 4 is smaller than the thickness T1 of the inner peripheral edge 41, as shown in FIG. 5 , a gap is formed between two adjacent corners 4 in the axial direction at a portion of the edgewise coil 1 where the corners 4 of multiple layers 21 overlap in the axial direction. This increases the surface area of ​​the edgewise coil 1, improving the heat dissipation of the edgewise coil 1. In other words, the portion of the edgewise coil 1 where multiple corners 4 overlap in the axial direction functions like a heat dissipation fin.

[0052] In the corner 4 that has been edgewise bent using the jigs 51 and 52, the conductor density of the inner peripheral edge 41 of the corner 4 is higher than the conductor density of the portion of the corner 4 excluding the inner peripheral edge 41. When the material of the rectangular wire 2 is copper, the copper density of the inner peripheral edge 41 of the corner 4 is higher than the copper density of the portion of the corner 4 excluding the inner peripheral edge 41. When the material of the rectangular wire 2 is aluminum, the aluminum density of the inner peripheral edge 41 of the corner 4 is higher than the aluminum density of the portion of the corner 4 excluding the inner peripheral edge 41.

[0053] In the edgewise coil 1 of one embodiment, the current density is relatively high at the inner peripheral edge 41 of the corner 4 where the conductor density is high (i.e., the portion with pressure marks on both sides in the thickness direction). The current density is relatively low in the portion of the corner 4 excluding the inner peripheral edge 41 (particularly the outer peripheral edge of the corner 4).

[0054] 2. Modifications The above embodiment is merely one of various embodiments of the present disclosure. The above embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved.

[0055] Modifications of the above embodiment are listed below. In the description of the modifications, the same components as those described in the above embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. The various modifications listed below can be applied in appropriate combination.

[0056] In the above embodiment, the thickness T1 of the inner peripheral edge 41 of the corner 4 is the same as the thickness of the rectangular wire 2 excluding the corners 4, but the thickness T1 of the inner peripheral edge 41 is not limited to this. The thickness T1 of the inner peripheral edge 41 may be larger than the thickness of the rectangular wire 2 excluding the corners 4, or may be smaller than the thickness of the rectangular wire 2 excluding the corners 4.

[0057] In other words, in the above embodiment, the thickness T1 of the inner peripheral edge 41 of the corner 4 of the rectangular wire 2 is the same as the thickness of the multiple straight portions 3 of the rectangular wire 2, but the thickness T1 of the inner peripheral edge 41 is not limited to this. The thickness T1 of the inner peripheral edge 41 may be greater than or smaller than the thickness of the multiple straight portions 3 of the rectangular wire 2. The thickness T1 of the inner peripheral edge 41 may be greater than or smaller than the thickness of the first straight portion 31 extending from the corner 4. The thickness T1 of the inner peripheral edge 41 may be greater than or smaller than the thickness of the second straight portion 32 extending from the corner 4.

[0058] In the above embodiment, it is preferable that the radius of curvature of the inner peripheral edge 41 of the corner 4 is 35% or less of the maximum plate width of the rectangular wire 2, but the radius of curvature of the inner peripheral edge 41 of the corner 4 is not limited to this range. The radius of curvature of the inner peripheral edge 41 of the corner 4 may exceed 35% of the maximum plate width of the rectangular wire 2, or may exceed 35% of the maximum width of each of the first straight portion 31 and the second straight portion 32 that are continuous through this corner 4.

[0059] In the above embodiment, each corner 4 of the rectangular wire 2 is formed by an edgewise bent portion after annealing, but this is not limited to this. At least one of the multiple corners 4 of the rectangular wire 2 may be formed by an edgewise bent portion without undergoing the annealing process.

[0060] In the above embodiment, the rectangular wire 2 is preferably made of copper or aluminum, but the material of the rectangular wire 2 is not limited to these. The rectangular wire 2 may also be made of a conductor other than copper or aluminum.

[0061] In the above embodiment, the edgewise coil 1 is formed so that the outer diameter gradually increases in the axial direction, but the shape of the edgewise coil 1 is not limited to this. The outer diameter of the edgewise coil 1 may also be formed to be uniform in the axial direction. Only some of the multiple layers 21 of the flat wire 2 that make up the edgewise coil 1 may be formed so that the outer diameter gradually increases in the axial direction.

[0062] 3. Summary As explained above based on the embodiment and various modified examples, the edgewise coil (1) of the first aspect is composed of a spiral flat wire (2) having a straight portion (3) and an edgewise bent corner portion (4). The corner portion (4) includes an arc-shaped inner peripheral edge portion (41). The inner peripheral edge portion (41) has a surface (410) with pressure marks. The conductor density of the inner peripheral edge portion (41) is higher than the conductor density of the corner portion (4) excluding the inner peripheral edge portion (41).

[0063] According to this aspect, the thickness of the inner peripheral edge portion (41) of the corner portion (4) of the spiral flat wire (2), which is inherently prone to increase in thickness due to edgewise bending, is reduced, and therefore, according to this aspect, it is possible to provide an edgewise coil (1) that is compact in the axial direction.

[0064] In the edgewise coil (1) of the second embodiment, the surface (410) with the processing marks has a smaller surface roughness than the surface of the other part of the corner portion (4) in the first embodiment.

[0065] The edgewise coil (1) of the third aspect is the first or second aspect, in which the thickness (T2) of the outer periphery of the corner portion (4) is smaller than the thickness (T1) of the inner periphery portion (41).

[0066] According to this embodiment, the surface area of ​​the edgewise coil (1) is increased, and heat dissipation is improved.

[0067] The edgewise coil (1) of the fourth aspect is any one of the first to third aspects, in which the thickness (T1) of the inner peripheral edge (41) of the corner portion (4) is the same as the thickness of the straight portion (3).

[0068] According to this aspect, since the inner peripheral edge portion (41) has the same thickness as the straight portion (3), the entire edgewise coil (1) can be effectively made compact in the axial direction.

[0069] The edgewise coil (1) of the fifth aspect is any one of the first to fourth aspects, in which the radius of curvature of the inner peripheral edge (41) is 35% or less of the maximum plate width of the rectangular wire (2).

[0070] According to this aspect, the entire edgewise coil (1) can be effectively made compact.

[0071] The edgewise coil (1) of the sixth aspect is any one of the first to fifth aspects, in which the corners (4) are portions that are edgewise bent after annealing.

[0072] According to this aspect, it is possible to provide an edgewise coil (1) having corners (4) that are bent edgewise well without causing cracks or the like.

[0073] The edgewise coil (1) of the seventh aspect is any one of the first to sixth aspects, wherein the material of the rectangular wire (2) is copper or aluminum.

[0074] According to this aspect, it is possible to provide an edgewise coil (1) made of copper or aluminum that is compacted in the axial direction.

[0075] The edgewise coil (1) of the eighth aspect is any one of the first to fifth aspects, in which the flat wire (2) includes a plurality of layers (21) that overlap each other in the axial direction of the edgewise coil (1), and the widths of the plurality of layers (21) are gradually wider as the layers (21) are located on one side of the axial direction.

[0076] According to this aspect, it is possible to provide an edgewise coil (1) that is compact in the axial direction and has a high conductor occupancy rate. By configuring a motor (9) using an edgewise coil (1) with a high conductor occupancy rate, it is possible to reduce coil resistance, copper loss, and temperature rise in the motor (9), thereby increasing motor efficiency.

[0077] The edgewise coil of the present disclosure can be easily made compact in the axial direction. Therefore, the edgewise coil of the present disclosure contributes to making a motor equipped with the edgewise coil compact. In this way, the edgewise coil of the present disclosure is industrially useful.

[0078] REFERENCE SIGNS LIST 1 Edgewise coil 2 Rectangular wire 21 Layer 3 Straight portion 31 First straight portion 32 Second straight portion 4 Corner portion 41 Inner peripheral edge portion 410 Surface T1 Thickness T2 Thickness

Claims

1. An edgewise coil made of a spiral flat wire having a straight portion and an edgewise bent corner portion, wherein the corner portion includes an arc-shaped inner peripheral edge portion, the inner peripheral edge portion has a surface with pressure marks, and the conductor density of the inner peripheral edge portion is higher than the conductor density of the corner portion excluding the inner peripheral edge portion.

2. The edgewise coil according to claim 1, wherein the surface with the processing marks has a smaller surface roughness than the surface of the other part of the corner.

3. The edgewise coil according to claim 1 or 2, wherein the thickness of the outer periphery of the corner portion is smaller than the thickness of the inner periphery portion.

4. The edgewise coil according to claim 1 or 2, wherein the thickness of the inner peripheral edge of the corner portion is the same as the thickness of the straight portion.

5. An edgewise coil according to claim 1 or 2, wherein the radius of curvature of the inner peripheral edge of the corner is 35% or less of the maximum plate width of the rectangular wire.

6. The edgewise coil according to claim 1 or 2, wherein the corner portion is a portion that has been edgewise bent after annealing.

7. The edgewise coil according to claim 1 or 2, wherein the rectangular wire is made of copper or aluminum.

8. An edgewise coil as claimed in claim 1 or 2, wherein the flat wire includes a plurality of layers overlapping each other in the axial direction of the edgewise coil, and the widths of the plurality of layers are arranged so that the layers located on one side in the axial direction gradually become wider.

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