Coil, coil assembly, flat wire processing device, and flat wire processing method

Abstract

To provide a coil and the like capable of preventing the same from forming thick corners without increasing the electrical resistance.SOLUTION: A coil 12 formed by winding a rectangular wire 50 by edgewise bending, includes multiple straight portions 51; and corners 52 connecting two adjacent straight portions 51 of the multiple straight portions 51. The rectangular wire 50 has a recess 53 formed by cutting out a part of the inner peripheral surface 50a of the rectangular wire 50 in the vicinity of the corner 52. The recess 53 is provided in only one of the two adjacent straight portions 51.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to a coil formed by bending a rectangular wire, a coil assembly including the coil, a rectangular wire processing device for bending a rectangular wire, and a rectangular wire processing method for bending a rectangular wire. [Background technology]

[0002] As one type of rotating electric machine, an electric motor that converts electrical energy into mechanical energy is known. Electric motors are used in a variety of products, such as household appliances and industrial equipment. For example, electric motors are used in a wide variety of applications, including home appliances such as vacuum cleaners, automobiles, and robots.

[0003] In recent years, there has been a demand for electric motors to be more efficient and less costly. A technique for increasing the space factor of the winding coils used in the stator of an electric motor is known as a method for improving the efficiency of an electric motor. By increasing the space factor of the winding coils, the loss caused by the current flowing through the winding coils when the electric motor is running can be suppressed, thereby improving the efficiency of the electric motor.

[0004] Conventionally, as one of the techniques for increasing the space factor of the winding coil in the stator of an electric motor, it has been proposed to use a deformed coil made by bending a rectangular wire edgewise as the winding coil. Edgewise coils are known as this type of deformed coil. For example, Patent Document 1 discloses a rotating electric machine using an edgewise coil as the winding coil of the stator. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-178457 A [Patent Document 2] Patent No. 4831125 Summary of the Invention [Problem to be solved by the invention]

[0006] An edgewise coil is made by performing edgewise bending processing on a rectangular wire. Specifically, as shown in Fig. 9(a), a rectangular wire 50X is brought into contact with a bending roller 2X, and as shown in Fig. 9(b), the rectangular wire 50X is bent in the edgewise direction to produce an edgewise coil.

[0007] At this time, tensile stress and compressive stress act on the corner portion (bent portion) of the rectangular wire 50X. Specifically, tensile stress acts on the outer periphery of the corner portion and compressive stress acts on the inner periphery of the corner portion, with the center line CL (neutral line) of the rectangular wire 50X shown by the two-dot chain line in FIG. 9 (b) as the boundary. Therefore, the thickness of the rectangular wire 50X decreases at the outer periphery of the corner portion, while the thickness of the rectangular wire 50X increases at the inner periphery of the corner portion. Therefore, the inner periphery of the corner portion shrinks, and the metal (thickness) constituting the rectangular wire 50X becomes surplus at the inner periphery. As a result, the metal that has shrunk and has nowhere to go rises in the plate thickness direction, and a thick portion is formed at the inner periphery of the corner portion of the rectangular wire 50X.

[0008] Therefore, in order to prevent the formation of thick portions at the corners, a technology has been proposed in the past in which a bulge 51X is formed by curving a portion of a rectangular wire 50X corresponding to one side of a rectangular coil 12X so that the portion bulges outward as a whole, as shown in FIG. 10 (Patent Document 2).

[0009] However, when the bulge 51X is formed in the portion corresponding to one side of the coil 12X, the electrical resistance of the coil 12X increases. In other words, even if the curve of the bulge 51X is gentler and the length of the side itself does not increase much compared to when the portion corresponding to one side of the coil is a straight portion, the coil 12X is formed by winding the rectangular wire 50X for multiple turns, and the increase in length due to each bulge 51X is accumulated, so that the circumference of the coil 12X as a whole becomes considerably long. As a result, the electrical resistance of the coil 12X may increase to a degree that cannot be ignored.

[0010] The present disclosure has been made to solve such problems, and aims to provide a coil, etc. that can prevent thick portions from being formed in corner portions without increasing electrical resistance. [Means for solving the problem]

[0011] In order to achieve the above-mentioned objective, one embodiment of the coil according to the present disclosure is a coil formed by winding a flat wire by edgewise bending, and has a plurality of straight sections and a corner section connecting two adjacent straight sections among the plurality of straight sections, and the flat wire has a recess formed so that a portion of the inner surface of the flat wire is recessed, and the recess is provided in only one of the two adjacent straight sections, near the corner section.

[0012] Furthermore, one aspect of a coil assembly according to the present disclosure comprises the above-described coil and a core to which the coil is attached, and the inner surface of the flat wire in each of the plurality of straight portions extends along the outer surface of the core.

[0013] In addition, one aspect of the flat wire processing apparatus according to the present disclosure is a flat wire processing apparatus that performs edgewise bending on a flat wire, and is equipped with a bending block having a protrusion that serves as a fulcrum for the edgewise bending, and a movable bending jig, and by moving the bending jig with the protrusion in contact with the flat wire, the flat wire is edgewise bent using the protrusion as a fulcrum.

[0014] In addition, one aspect of the flat wire processing method disclosed herein is a flat wire processing method in which edgewise bending is performed on a flat wire using a bending block having a protrusion and a bending jig, in which the flat wire is fixed between the bending block and the bending jig, and the bending jig is moved with the protrusion in contact with the flat wire, thereby performing edgewise bending on the flat wire using the protrusion as a fulcrum. Effect of the Invention

[0015] According to the present disclosure, it is possible to realize a coil or the like that can suppress the formation of thick portions at corners without increasing electrical resistance. [Brief description of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view of an electric motor according to an embodiment. [Diagram 2] FIG. 2 is a perspective view of a coil assembly according to the embodiment. [Diagram 3] FIG. 2 is an exploded view of the coil assembly according to the embodiment. [Figure 4] 4 is a cross-sectional view of the device taken along line IV-IV in FIG. 2. [Diagram 5] 5 is a cross-sectional view of the coil assembly taken along line VV in FIG. 4. [Figure 6] FIG. 2 is a front view of a coil according to an embodiment. [Figure 7] FIG. 2 is a diagram for explaining a flat wire processing method and a flat wire processing device according to an embodiment. [Figure 8] 13A and 13B are diagrams showing modified examples of a bending block and a recess formed by the bending block; [Figure 9] FIG. 1 is a diagram for explaining a conventional method for forming a rectangular wire. [Figure 10] FIG. 1 is a diagram showing a configuration of a coil disclosed in Patent Document 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, embodiments of the present disclosure will be described. Note that each of the embodiments described below shows a specific example of the present disclosure. Therefore, the numerical values, components, the arrangement and connection of the components, the steps, and the order of the steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not described in the independent claims showing the highest concept of the present disclosure will be described as optional components.

[0018] In addition, each drawing is a schematic diagram and is not necessarily a precise illustration. In each drawing, the same reference numerals are used for substantially the same configurations, and duplicated explanations are omitted or simplified.

[0019] In this embodiment, the radial direction of the stator 10 and the rotor 20 is defined as the "radial direction", and the rotation direction of the rotor 20 is defined as the "circumferential direction". In other words, the direction spreading from the axis C of the rotating shaft 23 is the "radial direction", and the direction going around the axis C of the rotating shaft 23 is the "circumferential direction". Therefore, the "radial direction" is a direction perpendicular to the direction of the axis C of the rotating shaft 23. In this specification, the terms "up" and "down" do not necessarily refer to the upward direction (vertically upward) and downward direction (vertically downward) in absolute spatial recognition.

[0020] (Embodiment) In the following embodiment, an electric motor will be described as an example of a rotating electric machine. First, the overall configuration of an electric motor 1 according to the embodiment will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view of an electric motor 1 according to the embodiment. Fig. 1 shows a cross section taken along a plane perpendicular to the direction of an axis C of a rotating shaft 23 of a rotor 20.

[0021] As shown in Fig. 1, the electric motor 1 includes a stator 10 and a rotor 20. The stator 10 and the rotor 20 are arranged opposite each other. The electric motor 1 in this embodiment is an inner rotor type motor in which the rotor 20 is arranged inside the stator 10. In addition to the stator 10 and the rotor 20, the electric motor 1 also includes components such as a motor case and bearings that support a rotating shaft 23, but for convenience, illustration and description of these components are omitted.

[0022] The stator 10 (stator) is disposed facing the rotor 20 with an air gap between them. A small air gap exists between the surface of the rotor 20 and the surface of the stator 10. In this embodiment, the stator 10 is disposed so as to surround the rotor core 21 of the rotor 20.

[0023] The stator 10 generates a magnetic force acting on the rotor 20. Specifically, the stator 10 is configured to generate a magnetic flux on an air gap surface between the stator 10 and the rotor core 21 of the rotor 20. For example, the stator 10 is configured such that N poles and S poles are generated alternately and repeatedly in the circumferential direction on the air gap surface between the stator 10 and the rotor core 21.

[0024] As shown in FIG. 1, in this embodiment, a stator 10 has a coil 12 and a stator core 11.

[0025] Coil 12 is a stator coil provided in stator 10 as a wound coil. Coil 12 is an armature winding of stator 10, and is configured to be wound around stator core 11. Specifically, coil 12 is wound around each of a plurality of teeth 11a of stator 10. Thus, a plurality of coils 12 is used in stator 10. Each of the plurality of coils 12 is configured to be wound around a respective one of the plurality of teeth 11a.

[0026] The multiple coils 12 are arranged at equal intervals along the circumferential direction so as to surround the rotor 20. Each coil 12 is housed in a corresponding slot 11c of the stator 10. The coils 12 are attached to the stator core 11. Specifically, the coils 12 are attached to the teeth 11a of the stator core 11 via an insulator (not shown in FIG. 1).

[0027] Stator core 11 is an iron core that serves as the core of stator 10. In the present embodiment, stator core 11 is composed of a plurality of teeth 11a and an annular yoke 11b.

[0028] Each of the multiple teeth 11a protrudes toward the axis C of the rotation shaft 23 of the rotor 20. Specifically, the multiple teeth 11a are provided radially in a direction perpendicular to the axis C of the rotation shaft 23 (radial direction).

[0029] A slot 11c for arranging the coil 12 is formed between two adjacent teeth 11a. That is, the slot 11c of the stator 10 is a region between two adjacent teeth 11a. The teeth 11a are arranged at equal intervals along the circumferential direction with the slot 11c formed between two adjacent teeth 11a. In this embodiment, the stator 10 has 18 teeth 11a, and therefore the number of slots in the stator 10 is 18.

[0030] Each tooth 11a extends so as to protrude radially inward from an annular yoke 11b. In other words, the yoke 11b is a back yoke formed on the outside of each tooth 11a. In this embodiment, the teeth 11a and the yoke 11b are manufactured separately, and the teeth 11a are fixed to the yoke 11b by fitting them into the yoke 11b.

[0031] Although the yoke 11b is configured as an integral unit, it may be divided into multiple pieces. When the yoke 11b is divided into multiple pieces, the yoke 11b is configured by connecting multiple divided arc yokes in an annular shape. For example, the yoke 11b may be configured of six equally divided arc yokes. In this case, three teeth 11a are fixed at equal intervals to one arc yoke.

[0032] The teeth 11a and the yoke 11b are each a laminated body formed by stacking a plurality of electromagnetic steel sheets. Each of the plurality of electromagnetic steel sheets is, for example, a punched steel sheet formed into a predetermined shape. The teeth 11a and the yoke 11b may be a bulk body made of a magnetic material.

[0033] Each of the teeth 11a is a magnetic pole tooth, and generates a magnetic force when the coil 12 is energized. In this embodiment, the coils 12 in the stator 10 are electrically connected as a three-phase winding so that the rotor 20 rotates as a three-phase synchronous motor. Specifically, the coils 12 are composed of unit coils for each of the three phases, U phase, V phase, and W phase, which are electrically out of phase with each other by 120 degrees. In other words, the coils 12 attached to each tooth 11a are energized and driven by three-phase AC that is energized in units of the U phase, V phase, and W phase. As a result, a main magnetic flux for rotating the rotor 20 is generated in each tooth 11a.

[0034] In this manner, in this embodiment, the teeth 11a are attached to the yoke 11b. Specifically, one coil assembly 100 is composed of one coil 12, one insulator 13, and one tooth 11a, and the coil assembly 100 is fitted and fixed to the yoke 11b. That is, the coil assembly 100 is a coil block in which one coil 12, one insulator 13, and one tooth 11a form one block. The electric motor 1 has a plurality of coil assemblies 100. Specifically, the electric motor 1 shown in FIG. 1 uses 18 coil assemblies 100. Each of the plurality of coil assemblies 100 is fixed to the stator core 11 by combining the teeth 11a of each coil assembly 100 with the yoke 11b. The detailed configurations of the coil assemblies 100 and the coils 12 will be described later.

[0035] The rotor 20 rotates due to the magnetic force of the stator 10. The rotor 20 also generates a magnetic force. Specifically, the rotor 20 is configured with a plurality of alternating N poles and S poles that generate magnetic flux in the circumferential direction. This allows the rotor 20 to generate a magnetic force that acts on the stator 10. In this embodiment, the direction of the magnetic flux generated from the rotor 20 is perpendicular to the direction of the axis C of the rotating shaft 23 (axial direction). In other words, the direction of the magnetic flux generated by the rotor 20 is the radial direction.

[0036] The rotor 20 has a rotor core 21, a plurality of permanent magnets 22, and a rotating shaft 23. The rotor 20 rotates about an axis C of the rotating shaft 23. In other words, the rotating shaft 23 serves as the center about which the rotor 20 rotates.

[0037] In this embodiment, rotor 20 is an embedded permanent magnet rotor (IPM rotor) in which permanent magnets 22 are embedded in rotor core 21. Therefore, electric motor 1 in this embodiment is an IPM motor.

[0038] Rotor core 21 is an iron core that becomes the core of rotor 20. In this embodiment, rotor core 21 is a laminated body in which a plurality of electromagnetic steel sheets are laminated in the direction of axis C of rotating shaft 23 (axial direction). Each of the plurality of electromagnetic steel sheets is, for example, a punched steel sheet formed into a predetermined shape. The plurality of electromagnetic steel sheets are fixed to one another by, for example, crimping. Note that rotor core 21 is not limited to being a laminated body of a plurality of electromagnetic steel sheets, and may be a bulk body made of a magnetic material.

[0039] The permanent magnets 22 are disposed in magnet insertion holes provided in the rotor core 21. In this embodiment, the rotor core 21 is provided with ten magnet insertion holes, and a plate-shaped permanent magnet 22 is inserted into each magnet insertion hole. As an example, the permanent magnets 22 are sintered magnets. Note that the permanent magnets 22 may also be bonded magnets.

[0040] The rotating shaft 23 is a long shaft, for example, a metal bar. The rotating shaft 23 is fixed to the rotor core 21. Specifically, the rotating shaft 23 is inserted into a through hole provided at the center of the rotor core 21 so as to extend on both sides of the rotor core 21 in the direction of the axis C, and is fixed to the rotor core 21. The rotating shaft 23 is fixed to the rotor core 21, for example, by press-fitting or shrink-fitting into the through hole of the rotor core 21. In the electric motor 1, one of the parts of the rotating shaft 23 protruding from the rotor core 21 functions as an output shaft. For example, a load such as a rotary fan is attached to the rotating shaft 23. Although not shown, the rotating shaft 23 is rotatably supported by a bearing such as a bearing.

[0041] In the electric motor 1 configured in this manner, when current is applied to the coil 12 of the stator 10, a field current flows through the coil 12, generating a magnetic field in the stator 10. This generates a magnetic flux from the stator 10 toward the rotor 20. Specifically, a magnetic flux is generated from each of the teeth 11a of the stator core 11 of the stator 10 toward the rotor 20. Meanwhile, in the rotor 20, a magnetic flux passing through the stator 10 is generated by the permanent magnets 22 arranged in the rotor core 21. A magnetic force generated by the interaction between the magnetic flux generated by the stator 10 and the magnetic flux generated by the permanent magnets 22 of the rotor 20 becomes a torque that rotates the rotor 20, and the rotor 20 rotates.

[0042] Next, detailed configurations of the coil assembly 100 and the coil 12 used in the electric motor 1 according to this embodiment will be described with reference to FIG. 1 and with reference to FIGS. 2 to 6. FIG.

[0043] Fig. 2 is a perspective view of a coil assembly 100 according to an embodiment, and Fig. 3 is an exploded view of the coil assembly 100. Fig. 4 is a cross-sectional view of the coil assembly 100 taken along line IV-IV in Fig. 2, and Fig. 5 is a cross-sectional view of the coil assembly 100 taken along line VV in Fig. 4. Fig. 6 is a front view of a coil 12 according to an embodiment.

[0044] 2 and 3, the coil assembly 100 is made up of a coil 12, an insulator 13, and teeth 11a. In the coil assembly 100, the coil 12 is attached to the teeth 11a via the insulator 13.

[0045] As shown in Figs. 2 to 5, the insulator 13 is interposed between the coil 12 and the teeth 11a. The insulator 13 is a cylindrical insulating frame that covers the teeth 11a. The insulator 13 is made of an insulating resin material such as polybutylene terephthalate (PBT). In this embodiment, the insulator 13 is separated into a first frame 13a and a second frame 13b. After the coil 12 is mounted on the cylindrical portion of the first frame 13a, the second frame 13b is fitted into the cylindrical portion of the first frame 13a, whereby the coil 12 can be mounted on the insulator 13. The coil assembly 100 can be produced by inserting the teeth 11a into the cylindrical portion of the insulator 13 on which the coil 12 is mounted.

[0046] As shown in Figs. 4 and 5, the coil 12 is an irregular coil, and is formed by winding a flat conductor, a rectangular wire 50, edgewise bending. In other words, the coil 12 is an edgewise coil, and has a winding section (winding section) formed by winding the rectangular wire 50 for a plurality of turns. The coil 12, which is an edgewise coil, is a high-density formed coil. By using the coil 12 configured in this manner, a higher space factor can be obtained compared to a round wire coil configured with a round wire. For example, the space factor of the coil 12 in this embodiment is 90% or more.

[0047] The rectangular wire 50 constituting the coil 12 can be a metal plate mainly composed of a low-resistance metal material such as copper or aluminum. In this embodiment, a copper plate made of a copper alloy is used as the rectangular wire 50. The thickness and width of the rectangular wire 50 are constant. As an example, the thickness of the rectangular wire 50 is 0.5 mm to 2 mm, and the width of the rectangular wire 50 is 5 mm to 15 mm.

[0048] In addition, the flat wire 50 is insulated in each turn in the winding part of the coil 12. In this case, by using an insulating coated metal plate as the flat wire 50, the flat wire 50 can be insulated in each turn. In addition, when using a flat wire 50 that is not insulating coated, by inserting an insulating film between the flat wire 50 in each turn of the winding part, the flat wire 50 can be insulated in each turn.

[0049] The winding portion of the coil 12 is formed by spirally winding a long rectangular wire 50 having a constant thickness and width so that each turn is approximately rectangular. That is, when viewed from the lamination direction of the rectangular wire 50 (when viewed from the radial direction of the stator 10), as shown in Figures 5 and 6, the rectangular wire 50 constituting the coil 12 is formed to have a substantially rectangular frame shape having four sides in each turn. By winding the rectangular wire 50 into the coil 12, as shown in Figures 5 and 6, one side of the rectangular wire 50 becomes the inner inner peripheral surface 50a (inner edge), and the other side of the rectangular wire 50 becomes the outer outer peripheral surface 50b (outer edge).

[0050] In this embodiment, the width of the winding portion of the coil 12 varies from turn to turn. Specifically, the coil 12 is formed so that the width of the winding portion gradually increases or decreases from the first turn to the final turn. As shown in FIG. 4, the winding portion in this embodiment is formed by winding the rectangular wire 50 in a spiral shape so that the inner diameter dimension is the same and the outer dimension gradually increases. In this case, as shown in FIG. 1, the coil 12 is arranged so that the part of the winding portion with the smallest outer dimension is located at the tip side of the tooth 11a and the part of the winding portion with the largest outer dimension is located at the base side (yoke 11b side) of the tooth 11a. The width of the winding portion of the coil 12 may be the same for all turns.

[0051] As shown in Figures 5 and 6, the coil 12 in which the flat wire 50 is wound in a spiral shape has a plurality of straight portions 51 and a corner portion 52 connecting two adjacent straight portions 51 among the plurality of straight portions 51 in each turn.

[0052] The straight portion 51 is a straight portion where the rectangular wire 50 is straight without being curved in each turn of the coil 12. That is, in the straight portion 51, the inner peripheral surface 50a and the outer peripheral surface 50b of the rectangular wire 50 are straight lines when viewed from the front of the coil 12, as shown in Figs. 5 and 6. Therefore, the width of the rectangular wire 50 in the straight portion 51 is constant. In addition, the corner portion 52 is a bent portion where the rectangular wire 50 is bent edgewise. The coil 12 has a plurality of corner portions 52.

[0053] In this embodiment, the rectangular wire 50 constituting the coil 12 is wound so that each turn is approximately rectangular. Therefore, the straight portions 51 are provided in one-to-one correspondence with the four sides of the rectangle. Specifically, the straight portions 51 have a first straight portion 51a, a second straight portion 51b, a third straight portion 51c, and a fourth straight portion 51d corresponding to each of the four sides. Specifically, since the rectangular wire 50 is wound so that each turn is rectangular, the first straight portion 51a and the third straight portion 51c correspond to a pair of long sides, and the second straight portion 51b and the fourth straight portion 51d correspond to a pair of short sides. As shown in FIG. 5, the inner peripheral surface 50a of the rectangular wire 50 in each of the straight portions 51 extends along the outer peripheral surface of the stator core 11. Specifically, an inner peripheral surface 50 a of the rectangular wire 50 in each straight portion 51 extends along the outer peripheral surface of the tooth 11 a of the stator core 11 with the insulator 13 interposed therebetween.

[0054] In addition, since the rectangular wire 50 constituting the coil 12 is wound so that each turn forms a substantially rectangular shape, the coil 12 has four corner portions 52, and the angles of the corner portions 52 are right angles. The multiple corner portions 52 are provided in one-to-one correspondence with the four corners of the rectangle. Specifically, the multiple corner portions 52 have a first corner portion 52a, a second corner portion 52b, a third corner portion 52c, and a fourth corner portion 52d, each corresponding to one of the four corners.

[0055] The flat wire 50 constituting the coil 12 has a recess 53 formed so that a part of the inner peripheral surface 50a of the flat wire 50 is recessed. The recess 53 is formed so that a part of the inner peripheral surface 50a of the flat wire 50 recedes toward the outer peripheral surface 50b. In other words, the recess 53 is a notched cutout portion provided so as to cut out a part of the inner peripheral surface 50a of the flat wire 50. The planar shape of the recess 53 (the cutout portion) is a shape including a sector. In this embodiment, the planar shape of the recess 53 is a semicircle with an inner angle of 180 degrees, which is a sector. Therefore, the inner shape line of the recess 53 includes a circular arc.

[0056] The recess 53 is provided in only one of the two adjacent straight portions 51 in the vicinity of the corner portion 52. In other words, the recess 53 is present in only one of the two adjacent straight portions 51 in one corner portion 52.

[0057] In the present embodiment, one recess 53 is provided in each of the four corner portions 52. That is, one recess 53 is provided in each of the four straight portions 51.

[0058] However, if the straight portion 51 having the recess 53 near the corner portion 52 connecting the two adjacent straight portions 51 is the first straight portion, and the other straight portion is the second straight portion, the recess 53 does not extend to the inner peripheral surface 50a of the flat wire 50 constituting the second straight portion on the straight line extending from the inner peripheral surface 50a of the flat wire 50 constituting the first straight portion. Specifically, as shown in FIG. 5, the recess 53 provided in the first straight portion 51a does not extend to the inner peripheral surface 50a of the flat wire 50 constituting the second straight portion 51b on the straight line L extending from the inner peripheral surface 50a of the flat wire 50 constituting the first straight portion 51a. In other words, the recess 53 provided in the first straight portion 51a does not protrude from the straight line L.

[0059] If the recesses 53 provided in the first straight portions 51a protruded from the straight line L, when the coils 12 were inserted into the teeth 11a of the stator core 11 to be attached, the coils 12 might hit corners of the teeth 11a or corners of the insulators 13, making it impossible to insert the coils 12 into the teeth 11a. In contrast, since the recesses 53 provided in the first straight portions 51a do not protrude from the straight line L, the coils 12 can be easily inserted into the teeth 11a of the stator core 11.

[0060] Next, the method of forming the coil 12 thus configured will be described. In this case, the coil 12 is formed by edgewise bending the flat wire 50. The flat wire processing method and flat wire processing device 200 for edgewise bending the flat wire 50 will be described with reference to Fig. 7. Fig. 7 is a diagram for explaining the flat wire processing method and flat wire processing device 200 according to the embodiment.

[0061] The flat wire processing device 200 according to the present embodiment is a processing device for edgewise bending the flat wire 50. As shown in Fig. 7, the flat wire processing device 200 includes a bending frame 2 (bending die), a movable bending jig 3, and a wire guide 4. The flat wire processing device 200 can be used as a manufacturing device for manufacturing the coil 12.

[0062] The bending workpiece 2 has a protrusion 2a which serves as a fulcrum for edgewise bending the rectangular wire 50 when edgewise bending the rectangular wire 50. The protrusion 2a is formed by protruding a part of the side surface of the bending workpiece 2. In this embodiment, the cross-sectional shape of the protrusion 2a is a semicircle. As an example, the protrusion 2a is a semicylindrical shape. In other words, the surface shape of the protrusion 2a is a cylindrical surface. The protrusion 2a may be a hemisphere or the like. The bending workpiece 2 is made of, for example, a steel material.

[0063] The bending jig 3 has a function of bending the rectangular wire 50. Specifically, the bending jig 3 bends the rectangular wire 50, for example, 90 degrees, by moving the portion of the rectangular wire 50 protruding from the bending frame 2 toward the bending frame 2 so as to bend the rectangular wire 50. The bending jig 3 may have a structure that sandwiches the rectangular wire 50 in the thickness direction. This allows the rectangular wire 50 to be stably bent edgewise.

[0064] In the rectangular wire processing method according to the present embodiment, the rectangular wire 50 is edgewise bent using the bending roll 2 and the bending jig 3.

[0065] Specifically, as shown in (a) of FIG. 7, the rectangular wire 50 guided by the wire guide 4 is fixed by the bending frame 2 and the bending jig 3. Then, as shown in (b) of FIG. 7, the bending jig 3 is moved with the protrusion 2a of the bending frame 2 in contact with the rectangular wire 50, so that the rectangular wire 50 is edgewise bent with the protrusion 2a as a fulcrum. In other words, the rectangular wire 50 is bent in the edgewise direction (parallel to the main surface of the rectangular wire 50). As a result, as shown in (c) of FIG. 7, the rectangular wire 50 is bent at a predetermined angle to form a corner portion 52 in the rectangular wire 50.

[0066] At this time, in the process of bending the rectangular wire 50, a tensile stress acts on the outer periphery of the corner portion 52 and a compressive stress acts on the inner periphery of the corner portion 52, with the center line CL (neutral line) of the rectangular wire 50 as the boundary. As a result, the thickness of the rectangular wire 50 decreases on the outer periphery of the corner portion 52, and increases on the inner periphery of the corner portion 52. In other words, the inner periphery of the corner portion 52 shrinks, and the metal (meat) that constitutes the rectangular wire 50 becomes excess.

[0067] In this embodiment, since the bending frame 2 is provided with a protrusion 2a, there is an empty space SP on the side of the protrusion 2a, as shown in FIG. 7(b). Therefore, the excess material caused by the shrinkage of the inner periphery of the corner portion 52 does not rise in the thickness direction of the rectangular wire 50, but flows into this empty space SP. In other words, the excess material caused by the shrinkage can escape into this empty space. In this way, the empty space SP functions as an escape portion for the excess material caused by the shrinkage to escape, and also functions as a material accumulation space for accumulating the material.

[0068] As a result, even if the rectangular wire 50 is bent by edgewise bending to shrink the inner periphery of the corner portion 52 and cause excess material, the excess material can be allowed to escape into the empty space SP, thereby preventing the formation of a thick portion on the inner periphery of the corner portion 52 due to the excess material caused by the shrinkage of the inner periphery of the corner portion 52.

[0069] Then, the rectangular wire 50 is successively formed with corners 52, and the rectangular wire 50 is bent into a rectangular shape and wound in a spiral shape to form a substantially rectangular coil 12. The coil 12 thus formed is prevented from forming thick portions at the corners 52. Moreover, the inner periphery of the corners 52 is shrunk, and the excess material is released into the free space SP on the side of the protrusion 2a, resulting in the formation of a recess 53 at the portion of the rectangular wire 50 where the protrusion 2a abuts. That is, the recess 53 is formed near the corners 52. In addition, as shown in FIG. 7(c), two straight portions 51 are formed so as to sandwich the corners 52. The recess 53 is formed only in one of the two straight portions 51.

[0070] As shown in Fig. 7(c) in this embodiment, the excess material generated when the inner periphery of the corner portion 52 shrinks flows to fill the entire width of the empty space SP, but this is not limited to the above. In other words, the excess material generated when the inner periphery of the corner portion 52 shrinks may flow to only a part of the width of the empty space SP. In this case, there may be a gap between the side of the bending frame 2 (the side below the protrusion 2a) and the inner periphery 50a of the rectangular wire 50 without the side of the bending frame 2 (the side below the protrusion 2a) coming into contact with the inner periphery 50a of the rectangular wire 50.

[0071] As described above, by edgewise bending the rectangular wire 50 using the bending block 2 provided with the protrusions 2a, as shown in FIG. 6, the coil 12 can be formed in which the recess 53 is provided in only one of the two adjacent straight parts 51 at the corner part 52, and no thick part is formed at the inner periphery of the corner part 52. That is, in the coil 12X disclosed in Patent Document 2, the bulge 51X is formed at the part corresponding to one side of the substantially rectangular coil 12X to prevent the thick part from being formed at the inner periphery of the corner part, but according to the coil 12 of the present embodiment, the part corresponding to one side of the substantially rectangular coil 12 is left as the straight part 51, and the thick part can be prevented from being formed at the inner periphery of the corner part 52. Therefore, the circumferential length of the entire coil 12 can be prevented from increasing, and the electrical resistance can be prevented from increasing.

[0072] In this manner, according to the coil 12 of the present embodiment, the formation of thick portions in the corner portions 52 can be suppressed without increasing the electrical resistance.

[0073] The shape and size of the recess 53 formed in the coil 12 correspond to the shape of the protrusion 2a of the bending block 2. Specifically, the recess 53 and the protrusion 2a are shaped to fit together. In this embodiment, the cross-sectional shape of the protrusion 2a is semicircular, so the shape of the recess 53 in plan view (the cut-out portion) is semicircular. The recess 53 and the protrusion 2a are fitted together so that they completely match as a whole, but this is not limited thereto, and they may be partially fitted together.

[0074] In the present embodiment, the planar shape of the recess 53 and the cross-sectional shape of the protrusion 2a are semicircular as shown in FIG. 8(a), and a part of the inner shape of the recess 53 and the outer shape of the protrusion 2a are semicircular arcs with an inner angle of 180°, but this is not limited thereto. For example, as shown in FIG. 8(b) to (d), a part of the inner shape of the recess 53 and the outer shape of the protrusion 2a may be arcs other than semicircular arcs. Specifically, in FIG. 8(b) to (d), a part of the inner shape of the recess 53 and the outer shape of the protrusion 2a are arcs with an inner angle of less than 180°. FIG. 8 shows a modified example of the bending frame 2 and the recess 53 formed by the bending frame 2. The unit of the numerical values ​​in FIG. 8 is "mm", and "R" indicates the radius of curvature. As shown in FIG. 8(a) to (d), the shape and size of the recess 53 are determined by the shape and size of the protrusion 2a.

[0075] In the present embodiment, the planar shape of the recess 53 and the cross-sectional shape of the protrusion 2a are semicircular, and the inner shape of the recess 53 and the outer shape of the protrusion 2a are composed of only arcs, but this is not limited thereto. For example, as shown in (e) to (h) of FIG. 8, a part of the inner shape of the recess 53 and a part of the outer shape of the protrusion 2a may be straight lines. Specifically, in (e) to (h) of FIG. 8, a part of the inner shape of the recess 53 and the outer shape of the protrusion 2a include arcs and straight lines. Note that a part of the inner shape of the recess 53 and the outer shape of the protrusion 2a may not include arcs and may be composed of only straight lines. For example, a part of the inner shape of the recess 53 and the outer shape of the protrusion 2a may be composed of multiple sides of a polygon such as a triangle, a rectangle, or a pentagon. In other words, the planar shape of the recess 53 and the cross-sectional shape of the protrusion 2a may be a part of a polygon.

[0076] 8(a) to (h), the side surface (side surface of the free space SP) below the protrusion 2a of the bending workpiece 2 may be an inclined surface. In this case, as shown in FIG. 8(i), the side surface of the bending workpiece 2 may be an inclined surface, and the corner of the bending core 2 may be an acute angle, and this corner may be the protrusion 2a. However, as shown in FIG. 8(a) to (h), it is better to form the protrusion 2a by making a part of the side surface of the bending workpiece 2 protrude.

[0077] (Modification) While the coil 12 and the like according to the present disclosure have been described above based on the embodiments, the present disclosure is not limited to the above-described embodiments.

[0078] For example, in the above embodiment, the teeth 11a are configured separately from the yoke 11b, but this is not limiting. Specifically, the teeth 11a and the yoke 11b may be configured integrally.

[0079] In addition, in the above embodiment, the number of slots in the stator 10 is 18, but this is not limited to this. Similarly, in the above embodiment, the number of magnetic poles in the rotor 20 is 10 (i.e., the number of permanent magnets 22 is 10), but this is not limited to this. Any number can be applied as the number of slots in the stator 10 and the number of magnetic poles in the rotor 20.

[0080] In the above embodiment, the rotor 20 is an IPM rotor, but this is not limiting. For example, when a permanent magnet type rotor is used as the rotor 20, a surface permanent magnet type rotor (SPM rotor) in which multiple permanent magnets are provided on the outer surface of the rotor core may be used.

[0081] In the above embodiment, the electric motor 1 is used as an example of a rotating electric machine, but the present invention is not limited thereto. For example, a rotating electric machine using the coil 12 may be a generator. In addition, the coil 12 is used as a winding coil of the stator 10, but the present invention is not limited thereto, and the coil 12 may be used as various coils of products other than the stator.

[0082] In addition, the present disclosure also includes forms obtained by applying various modifications conceived by a person skilled in the art to each of the above embodiments, and forms realized by arbitrarily combining the components and functions of each of the above embodiments within the scope of the present disclosure. In addition, the present disclosure also includes any combination of one or more components in each of the multiple claims described in the claims at the time of filing of this application. In addition, when the cited-form claims described in the claims at the time of filing of this application are made into a multiple claim or multiple multiple claim so as to cite any multiple claims (for example, when the cited-form claims are made into a multiple claim or multiple multiple claim so as to cite all the upper claims for each claim), all forms obtained by combining all the claims included in the multiple claim or multiple multiple claim are also included in the present disclosure. [Industrial Applicability]

[0083] The technology disclosed herein can be widely used in a variety of products that use coils, including rotating electrical machines such as electric motors. [Explanation of symbols]

[0084] 1 electric motor 2 Bending frame 2a Protrusion 3 Bending jig 4 Line Guide 10 Stator 11 Stator core 11a Teeth 11b York 11c Slot 12 Coils 13 Insulator 13a First frame 13b Second frame 20 Rotors 21 Rotor core 22 Permanent magnets 23 Rotation axis 50 Flat wire 50a Inner surface 50b Outer surface 51 Straight section 51a First Straight Section 51b 2nd Straight Section 51c 3rd Straight Section 51d 4th straight section 52 Corner section 52a First corner 52b Second corner 52c 3rd corner 52d 4th corner 53 Recess 100 Coil assembly 200 Flat wire processing equipment

Claims

1. A coil formed by winding a rectangular wire by edgewise bending, A plurality of straight portions; and a corner portion connecting two adjacent straight portions among the plurality of straight portions, The rectangular wire has a recess formed so that a part of an inner peripheral surface of the rectangular wire is recessed, the recess is provided in only one of the two adjacent straight portions near the corner portion, coil.

2. The planar shape of the recess includes a sector shape. The coil according to claim 1 .

3. The inner shape of the recess includes an arc. The coil according to claim 1 .

4. A part or all of the inner shape line of the recess is a straight line. The coil according to claim 1 .

5. Of the two adjacent straight portions, the one in which the recess is provided near the corner portion connecting the two adjacent straight portions is defined as a first straight portion, and the other straight portion that is not the first straight portion is defined as a second straight portion. The inner peripheral surface of the rectangular wire constituting the second straight portion, which exists on a straight line extending from the inner peripheral surface of the rectangular wire constituting the first straight portion, is not covered by the recess. The coil according to claim 1 .

6. Each of the straight portions is provided with one of the recesses. The coil according to claim 1 .

7. The angle of the corner portion is a right angle. The coil according to claim 1 .

8. A coil according to any one of claims 1 to 7; a core to which the coil is attached; The inner peripheral surface of the rectangular wire in each of the straight portions extends along the outer peripheral surface of the core. Coil assembly.

9. A flat wire processing device that performs edgewise bending on a flat wire, a bending block having a protrusion serving as a fulcrum for the edgewise bending; A movable bending jig is provided, The bending jig is moved with the protrusion in contact with the rectangular wire, thereby performing edgewise bending on the rectangular wire with the protrusion as a fulcrum. Flat wire processing equipment.

10. The bending jig has a structure in which the rectangular wire is sandwiched in the thickness direction. The rectangular wire processing apparatus according to claim 9.

11. A method for edgewise bending a rectangular wire using a bending tool having a protrusion and a bending jig, comprising the steps of: The flat wire is fixed by the bending block and the bending jig, and the bending jig is moved with the protrusion in contact with the flat wire, thereby performing edgewise bending on the flat wire with the protrusion as a fulcrum. Flat wire processing method.

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