Winding structure, electric motor, and method for producing winding structure

Abstract

Provided are a winding structure with excellent heat dissipation properties, an electric motor using the same, and a method for producing the winding structure. A winding coil (12) is a winding structure obtained by winding a flat wire (12a), and the flat wire (12a) has a layered structure formed by layering a metal layer (31) in the thickness direction of the flat wire (12a). In the layered structure, at least one thermally conductive layer (32) having a higher thermal conductivity than the metal layer (31) is inserted in the thickness direction of the flat wire (12a). This makes it possible to obtain a winding structure with excellent heat dissipation properties.

Description

Winding structure, electric motor, and method of manufacturing winding structure

[0001] The present disclosure relates to a winding structure used in electric motors, generators, inductors, power choke coils, etc., and to an electric motor including the same.

[0002] BACKGROUND ART Electric motors (motors, servo motors, brushless motors, etc.) are used in a variety of products, including home appliances such as electric vacuum cleaners, automobiles, factory equipment, semiconductor processing equipment (mounters, dicers), processing machines (CNC), and multi-axis robots.

[0003] There has long been a demand for higher efficiency in electric motors. One method for improving the efficiency of electric motors is to increase the space factor of the winding coils used in the stator of the electric motor. Increasing the space factor of the winding coils can reduce losses caused by the current flowing through the winding coils when the electric motor is running, thereby improving the efficiency of the electric motor.

[0004] As one technique 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 edgewise bending a rectangular wire as the winding coil (see, for example, Patent Document 1).

[0005] JP 2016-85846 A

[0006] When a current flows through a winding coil, heat is generated from the winding coil, causing the temperature of the winding coil to rise, which can lead to a deterioration in the characteristics of the motor. In particular, when a non-circular coil is used as the winding coil, the heat generated in the rectangular wire is difficult to dissipate, and the heat tends to build up inside the winding coil. As a result, the temperature of the winding coil rises.

[0007] In addition to electric motors, there is also a need for higher currents in generators, transformers, inductors, power choke coils, and other devices that also use wound coils, making it important to improve efficiency by reducing heat.

[0008] The present disclosure has been made to solve such problems, and aims to provide a winding structure, an electric motor, and a method for manufacturing a winding structure that are excellent in heat dissipation properties.

[0009] In order to achieve the above object, one aspect of the winding structure according to the present disclosure is a winding structure in which a flat wire is wound, the flat wire having a laminated structure formed by stacking metal layers in the thickness direction of the flat wire, and at least one thermally conductive layer having a higher thermal conductivity than the metal layer is inserted in the thickness direction of the flat wire into the laminated structure.

[0010] Furthermore, another aspect of the electric motor according to the present disclosure includes a stator and a rotor that rotates due to the magnetic force of the stator, the stator having a stator core with a plurality of teeth and a winding coil wound around the plurality of teeth, and the winding coil is the winding structure of the above aspect.

[0011] Furthermore, a method for manufacturing a winding structure according to another aspect of the present disclosure is the method for manufacturing a winding structure according to the above aspect, and includes a step of forming the laminated structure by a sheet AM (Additive Manufacturing) method.

[0012] According to the winding structure, electric motor, and method for manufacturing a winding structure of the present disclosure, it is possible to realize a winding structure and electric motor with excellent heat dissipation properties.

[0013] 1 is a cross-sectional view of an electric motor according to an embodiment; FIG. 2 is an enlarged view showing a portion of a stator in an electric motor according to an embodiment; FIG. 3 is a perspective view of a winding coil used in an electric motor according to an embodiment; FIG. 4 is an enlarged cross-sectional view of an area IV surrounded by a dashed dotted line in FIG. 2; FIG. 5 is a cross-sectional perspective view of a flat wire constituting the winding coil according to an embodiment; FIG. 6 is an exploded perspective view of a flat wire constituting the winding coil according to an embodiment; FIG. 7 is a cross-sectional perspective view of a conventional flat wire; FIG. 8 is a cross-sectional perspective view of a flat wire according to an embodiment; FIG. 9 is a partial cross-sectional view of an electric motor including winding coils of comparative examples 1 and 2; FIG. 10 is a partial cross-sectional view of an electric motor including winding coils of examples 1, 2, and 3; FIG. 11 is a diagram showing maximum temperatures and average temperatures at each portion in the winding coils of comparative examples 1 and 2 and the winding coils of examples 1, 2, and 3; FIG. 12 is a temperature contour diagram when the winding coil of comparative example 1 is used; FIG. 13 is a temperature contour diagram when the winding coil of comparative example 2 is used; FIG. 14 is a temperature contour diagram when the winding coil of example 1 is used; FIG. 15 is a temperature contour diagram when the winding coil of example 2 is used; FIG. 16 is a temperature contour diagram when the winding coil of example 3 is used; FIG. 17 is a cross-sectional perspective view showing the configuration of a flat wire constituting the winding coil according to modification 1. Fig. 10 is an exploded perspective view showing the configuration of flat wires that make up the winding coil according to Modification 1. Fig. 11 is a cross-sectional view showing a state in which the winding coil according to Modification 2 is mounted on a stator.

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, arrangement positions and connection forms of the components, etc. 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 that represent the highest concept of the present disclosure will be described as optional components.

[0015] Note that each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, the scales and the like do not necessarily match in each figure. Furthermore, in all figures, substantially the same components are given the same reference numerals, and duplicate explanations are omitted or simplified.

[0016] Furthermore, 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. In this embodiment, for convenience, the direction in which the axis C of the rotating shaft 23 extends is defined as the upward / downward direction. However, this upward / downward direction may differ from the actual upward / downward direction depending on the usage state of the electric motor 100, etc. In addition, 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 extending from the axis C of the rotating shaft 23 as the center is defined as the "radial direction," and the direction circumferentially around the axis C of the rotating shaft 23 as the center is defined as the "circumferential direction." Therefore, the "radial direction" is a direction perpendicular to the direction of the axis C of the rotating shaft 23 (also simply referred to as the "axial direction").

[0017] (Embodiment) In the following embodiment, an electric motor 100 will be described as an example of a rotating electric machine. First, the overall configuration of the electric motor 100 according to the embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a cross-sectional view of the electric motor 100 according to the embodiment. Fig. 1 shows a cross-section taken along a plane perpendicular to the direction of the axis C of the rotating shaft 23 of the rotor 20. Fig. 2 is an enlarged view showing a portion of the stator 10 in the electric motor 100 according to the embodiment.

[0018] As shown in Fig. 1, the electric motor 100 includes a stator 10 and a rotor 20. The stator 10 and the rotor 20 are arranged opposite each other. The electric motor 100 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 100 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.

[0019] The stator 10 is disposed opposite 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.

[0020] The stator 10 generates a magnetic force that acts 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 so that north and south poles are generated alternately in the circumferential direction on the air gap surface between the stator 10 and the rotor core 21.

[0021] As shown in FIGS. 1 and 2, in this embodiment, a stator 10 has a winding coil 12 and a stator core 11.

[0022] The winding coil 12 is a stator coil provided in the stator 10. The winding coil 12 is an armature winding of the stator 10, and is configured to be wound around the stator core 11. Specifically, the winding coil 12 is wound around each of the plurality of teeth 11a of the stator 10. Therefore, the stator 10 uses a plurality of winding coils 12. The plurality of winding coils 12 are configured to be wound around each of the plurality of teeth 11a.

[0023] The winding coils 12 are arranged at equal intervals around the rotor 20 in the circumferential direction. Each winding coil 12 is housed in one slot 11c of the stator 10. The winding coils 12 are attached to the stator core 11. In this embodiment, the winding coils 12 are directly attached to the teeth 11a of the stator core 11. That is, the winding coils 12 are in contact with the teeth 11a of the stator core 11 and are attached to the teeth 11a of the stator core 11 without an insulating frame (coil bobbin). Note that the insulating frame here is different from the insulating layer and insulating member of the winding structure described below, and serves to insulate the winding coils 12 from the stator core 11. In other words, if the metal layers constituting the windings in the winding structure described below maintain high insulation properties due to the insulating layer and insulating member, an insulating frame is not necessary. The detailed structure of the winding coils 12 will be described later.

[0024] The stator core 11 is an iron core that serves as the core of the stator 10. In this embodiment, the stator core 11 is made up of a plurality of teeth 11a and an annular yoke 11b.

[0025] Each of the multiple teeth 11 a protrudes toward the axis C of the rotation shaft 23 of the rotor 20. Specifically, the multiple teeth 11 a are provided radially in a direction perpendicular to the axis C of the rotation shaft 23 (radial direction).

[0026] A slot 11c for arranging the winding coil 12 is formed between two adjacent teeth 11a. In other words, the slot 11c of the stator 10 is the 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.

[0027] 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 fabricated separately, and the teeth 11a are fixed to the yoke 11b by fitting them into the yoke 11b.

[0028] Although the yoke 11b is configured as a single unit, it may also be divided into multiple pieces. When the yoke 11b is divided into multiple pieces, the yoke 11b is configured by connecting the divided arc yokes in an annular shape. For example, the yoke 11b may be configured from six equally divided arc yokes. In this case, three teeth 11a are fixed at equal intervals to one arc yoke.

[0029] Each of the teeth 11 a and the yoke 11 b is a laminated body formed by stacking multiple electromagnetic steel sheets. Each of the multiple electromagnetic steel sheets is, for example, a stamped steel sheet formed into a predetermined shape. The teeth 11 a and the yoke 11 b may also be a bulk body made of a magnetic material.

[0030] Each of the plurality of teeth 11 a is a magnetic pole tooth, and generates a magnetic force when current is applied to the winding coil 12. In this embodiment, the plurality of winding 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 plurality of winding coils 12 are composed of unit coils for three phases, namely, U-phase, V-phase, and W-phase, which are electrically out of phase with each other by 120 degrees. In other words, the winding coils 12 attached to each tooth 11 a are energized and driven by three-phase alternating current that is applied to each of the U-phase, V-phase, and W-phase units. As a result, a main magnetic flux for rotating the rotor 20 is generated in each tooth 11 a.

[0031] In this manner, in this embodiment, the plurality of teeth 11 a are attached to the yoke 11 b afterward. Specifically, a coil assembly consisting of one winding coil 12 and one tooth 11 a is fitted and fixed to the yoke 11 b.

[0032] As shown in FIG. 1 , 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 north and south 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.

[0033] The rotor 20 has a rotor core 21, a plurality of permanent magnets 22, and a rotating shaft 23. The rotor 20 rotates around an axis C of the rotating shaft 23. In other words, the rotating shaft 23 is the center around which the rotor 20 rotates.

[0034] 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 100 in this embodiment is an IPM motor.

[0035] The rotor core 21 is an iron core that forms the core of the rotor 20. In this embodiment, the rotor core 21 is a laminated body in which a plurality of electromagnetic steel sheets are stacked in the direction of the axis C of the 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 the rotor core 21 is not limited to a laminated body of a plurality of electromagnetic steel sheets, and may also be a bulk body made of a magnetic material.

[0036] 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. However, the permanent magnets 22 may also be bonded magnets.

[0037] The rotating shaft 23 is a long shaft, such as a metal rod. The rotating shaft 23 is fixed to the rotor core 21. Specifically, the rotating shaft 23 is inserted into a through-hole provided in 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 100, one of the portions 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 bearings or the like.

[0038] In the electric motor 100 configured as described above, when current is applied to the winding coils 12 of the stator 10, a field current flows through the winding coils 12, generating a magnetic field in the stator 10. This generates magnetic flux from the stator 10 toward the rotor 20. Specifically, magnetic flux is generated from each of the teeth 11 a of the stator core 11 of the stator 10 toward the rotor 20. Meanwhile, in the rotor 20, 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.

[0039] Next, the detailed configuration of the winding coil 12 used in the electric motor 100 according to this embodiment will be described with reference to FIGS. 3 to 6. FIG. 3 is a perspective view of the winding coil 12 used in the electric motor 100 according to this embodiment. FIG. 4 is an enlarged cross-sectional view of an area IV surrounded by a dashed line in FIG. 2. FIG. 5 is a cross-sectional perspective view of the flat wire 12a that constitutes the winding coil 12. FIG. 6 is an exploded perspective view of the flat wire 12a that constitutes the winding coil 12. Note that the first insulating member 51 and the second insulating member 52 are omitted from FIGS. 5 and 6.

[0040] As shown in Figures 3 and 4, the winding coil 12 is an example of a winding structure and has a structure in which a flat wire 12a is wound. In other words, the winding coil 12 has a winding portion (winding portion) formed by winding the flat wire 12a multiple times. By using the flat wire 12a as the electric wire that constitutes the winding coil 12, a higher space factor can be obtained compared to when a round wire is used. As an example, the space factor of the winding coil 12 is 96% to 98%. In this embodiment, the flat wire 12a that constitutes the winding coil 12 is a rectangular wire.

[0041] The winding coil 12 is wound spirally around the teeth 11a of the stator core 11. In this embodiment, the flat wire 12a constituting the winding coil 12 is wound so that each turn has a substantially rectangular shape, as shown in FIG. 3, to fit the teeth 11a, which have a rectangular cross section.

[0042] In this embodiment, the width of the winding portion of the winding coil 12 varies from turn to turn. Specifically, the winding coil 12 is formed so that the width of the winding portion gradually increases or decreases from the first turn to the last turn. As shown in FIG. 4 , the winding portion of the winding coil 12 in this embodiment has the same inner diameter and the flat wire 12a wound spirally so that the outer dimensions gradually increase. In this case, as shown in FIG. 2 , the winding coil 12 is arranged so that the part with the smallest outer dimension is located at the tip of the tooth 11a and the part with the largest outer dimension is located at the base of the tooth 11a (toward the yoke 11b). Note that the width of the winding portion of the winding coil 12 may be the same for all turns.

[0043] As described above, the winding coil 12 in this embodiment has a structure in which the flat wire 12a is wound. However, it is not formed by edgewise bending a single rectangular wire, but rather by a sheet construction method in which multiple sheet-like sheet layers (thin films) are sequentially stacked. For example, the winding coil 12 can be formed by a sheet construction method such as a sheet lamination method or a sheet AM (Additive Manufacturing) method. Since the winding coil 12 in this embodiment contains a metal material, it is formed by a sheet AM technique using metal AM technology. For example, when forming the winding coil 12 by the sheet AM method, multiple sheet layers can be sequentially formed and then pressure applied to crimp and fix the multiple sheet layers. Furthermore, multiple sheet layers can also be melt-fixed by applying heat in addition to pressure. In this embodiment, the winding coil 12 is formed by multi-material AM technology, which allows different materials to be simultaneously stacked. In this embodiment, the winding coil 12 is formed by the sheet AM method, but the method is not limited to this, and the winding coil 12 can also be formed by a conventional AM method. For example, when forming the winding coil 12 by a conventional AM method other than the sheet AM method, the winding coil 12 can be formed by using an AM device that simultaneously forms ceramic and metal by a method called DLP (Digital Light Processing) using UV light (ultraviolet) irradiation.

[0044] 4 and 5, the flat wire 12a constituting the winding coil 12 has a laminated structure in which metal layers 31 and thermally conductive layers 32 are stacked in the thickness direction of the flat wire 12a. The flat wire 12a is composed of a plurality of metal layers 31 and a plurality of thermally conductive layers 32. Specifically, the flat wire 12a has a structure in which the metal layers 31 and the thermally conductive layers 32 are alternately stacked one by one. In this way, the winding coil 12 has a laminated flat wire structure.

[0045] As shown in Figures 4 and 5, in this embodiment, the flat wire 12a has a laminated structure of four metal layers 31 and five thermally conductive layers 32, but this is not limited thereto. Furthermore, in the laminated structure of the metal layers 31 and the thermally conductive layers 32, the thermally conductive layers 32 are the outermost layers in the thickness direction of the flat wire 12a, but this is not limited thereto. For example, the metal layers 31 may be the outermost layers in the thickness direction of the flat wire 12a. However, from the perspective of heat dissipation, it is preferable that the thermally conductive layers 32, which have a higher thermal conductivity than the metal layers 31, be the outermost layers. This is because, although it depends on the driving conditions of the electric motor 100, the current density distribution in the flat wire 12a is distributed outward due to the skin effect in electric motors 100 that rotate at higher speeds.

[0046] As shown in Figures 5 and 6, each of the multiple metal layers 31 is a sheet-like layer with a uniform thickness. The multiple metal layers 31 have the same width and thickness, but this is not limited to this. Furthermore, each of the multiple thermally conductive layers 32 is a sheet-like layer with a uniform thickness. The multiple thermally conductive layers 32 have the same width and thickness, but this is not limited to this. The thickness of the metal layer 31 and the thickness of the thermally conductive layer 32 may be the same or different. In this embodiment, the thickness of the metal layer 31 is thicker than the thickness of the thermally conductive layer 32. The width of the metal layer 31 and the width of the thermally conductive layer 32 are the same, but they may be different.

[0047] The metal layer 31 is a sheet layer formed of a metal material. In this embodiment, the metal layer 31 is a copper layer (copper foil) made of copper. The metal material constituting the metal layer 31 is not limited to copper, and a metal material with high conductivity, such as a copper alloy or aluminum, can be used as appropriate.

[0048] The thermally conductive layer 32 is a sheet layer (high thermally conductive sheet) having a higher thermal conductivity than the metal layer 31. The thermally conductive layer 32 may be made of a conductive material such as a metal material, or may be made of a thermally conductive sheet coated with an insulating material. In other words, the thermally conductive layer 32 may be conductive or insulating. In this embodiment, the thermally conductive layer 32 is a graphite layer (graphite sheet) made of graphite. Specifically, the thermally conductive layer 32 is an insulating graphite layer. Note that the material constituting the thermally conductive layer 32 is not limited to graphite, and other materials with high thermal conductivity, such as boron nitride (BN), diamond, or diamond-like carbon, may be used as appropriate.

[0049] 4, the flat wire 12a constituting the winding coil 12 has a first insulating layer 41 and a second insulating layer 42. The first insulating layer 41 and the second insulating layer 42 are made of an insulating material. The first insulating layer 41 and the second insulating layer 42 are sheet layers laminated on the laminated structure of the metal layer 31 and the thermally conductive layer 32.

[0050] The first insulating layer 41 covers one of a pair of lamination surfaces (first lamination surface) of the lamination structure of the metal layer 31 and the thermally conductive layer 32. The first insulating layer 41 covers the lamination surface on the outer side (the tip side of the tooth 11 a) of the lamination structure of the metal layer 31 and the thermally conductive layer 32 for each turn of the winding coil 12 in the radial direction of the stator 10. In this embodiment, in the lamination structure of the metal layer 31 and the thermally conductive layer 32 for each turn, the outermost layer on the tip side of the tooth 11 a is the thermally conductive layer 32, so the first insulating layer 41 is formed on the surface of this thermally conductive layer 32.

[0051] The second insulating layer 42 covers the other of a pair of lamination surfaces (second lamination surface) of the lamination structure of the metal layer 31 and the thermally conductive layer 32. The second insulating layer 42 covers the lamination surface on the inner side (the base side of the tooth 11 a) of the lamination structure of the metal layer 31 and the thermally conductive layer 32 for each turn of the winding coil 12 in the radial direction of the stator 10. In the embodiment, in the lamination structure of the metal layer 31 and the thermally conductive layer 32 for each turn, the outermost layer on the base side of the tooth 11 a is the thermally conductive layer 32, so the second insulating layer 42 is formed on the surface of this thermally conductive layer 32.

[0052] In this way, in the laminated structure of the metal layer 31 and the thermally conductive layer 32, both sides of each turn of the winding coil 12 in the lamination direction are sandwiched between the first insulating layer 41 and the second insulating layer 42. This allows the flat wire 12a to be insulated for each turn of the winding coil 12.

[0053] The first insulating layer 41 and the second insulating layer 42 are arranged in the stacking direction of the metal layer 31 and the thermally conductive layer 32, and therefore can be formed together with the metal layer 31 and the thermally conductive layer 32 by the sheet AM method. This prevents intermixing at the interface between the insulating material and the metal material. The first insulating layer 41 and the second insulating layer 42 may be formed in a separate process after the laminated structure of the metal layer 31 and the thermally conductive layer 32 is formed by the sheet AM method. For example, after the laminated structure of the metal layer 31 and the thermally conductive layer 32 is formed, the first insulating layer 41 and the second insulating layer 42 may be formed by spraying an insulating material such as a resin material or a ceramic material, or by dip molding.

[0054] 4, the flat wire 12a constituting the winding coil 12 further includes a first insulating member 51 and a second insulating member 52. The first insulating member 51 and the second insulating member 52 are made of an insulating material.

[0055] The first insulating member 51 covers one side surface of the laminated structure of the metal layer 31 and the thermally conductive layer 32. Specifically, the first insulating member 51 covers the side surface on the inner circumferential side (toward the teeth 11 a) of the laminated structure of the metal layer 31 and the thermally conductive layer 32.

[0056] The second insulating member 52 covers the other side surface of the laminated structure of the metal layer 31 and the thermally conductive layer 32. Specifically, the second insulating member 52 covers the side surface on the outer periphery side of the laminated structure of the metal layer 31 and the thermally conductive layer 32.

[0057] In this way, the laminated structure of the metal layer 31 and the thermally conductive layer 32 has both sides in a direction perpendicular to the lamination direction (thickness direction of the flat wire 12a) sandwiched between the first insulating member 51 and the second insulating member 52 over the entire length of the flat wire 12a. As a result, in a cross-sectional view when cut along a plane perpendicular to the extension direction of the flat wire 12a (direction in which current flows through the flat wire 12a), the laminated structure of the metal layer 31 and the thermally conductive layer 32 is entirely surrounded by the first insulating layer 41, the second insulating layer 42, the first insulating member 51, and the second insulating member 52. In other words, in a cross-sectional view when cut along a plane perpendicular to the extension direction of the flat wire 12a, the entire laminated structure of the metal layer 31 and the thermally conductive layer 32 is surrounded by insulating material, and the metal layer 31 and the thermally conductive layer 32 are not exposed.

[0058] The first insulating member 51 and the second insulating member 52 can be formed by a sheet AM method or a multi-material AM method after forming a laminated structure of the metal layer 31 and the thermal conduction layer 32 and the first insulating layer 41 and the second insulating layer 42, or by a separate process such as spraying or dip molding.

[0059] The first insulating layer 41, the second insulating layer 42, the first insulating member 51, and the second insulating member 52 are made of an insulating resin material or inorganic material.

[0060] The first insulating layer 41 and the second insulating layer 42 may be made of the same insulating material, or may be made of different insulating materials.

[0061] The first insulating member 51 and the second insulating member 52 may be made of the same insulating material or different insulating materials. When the first insulating member 51 and the second insulating member 52 are made of different insulating materials, for example, the first insulating member 51 can be made of an inorganic material and the second insulating member 52 can be made of a resin material.

[0062] In the present embodiment, when a resin material is used as the insulating material, for example, a resin material used for enameled wires may be used, or a resin material such as polyvinyl formal, polyurethane, polyester, polyesterimide, polyamideimide, or polyimide may be used.

[0063] Furthermore, when an inorganic material is used as the insulating material, for example, a ceramic material can be used. Ceramic materials have thermal conductivity that is one to two orders of magnitude higher than that of general resin materials. Examples of ceramic materials that can be used include aluminum oxide (alumina), SiN, AlN, BN, and SiC, which have thermal conductivity of several tens to several hundreds of W / mK.

[0064] Furthermore, the first insulating layer 41, the second insulating layer 42, the first insulating member 51, and the second insulating member 52 may be made of the same insulating material or different insulating materials. In this embodiment, the first insulating layer 41, the second insulating layer 42, the second insulating member 52, and the first insulating member 51 are made of different insulating materials. In this case, the thermal conductivity of the first insulating member 51 is preferably higher than the thermal conductivity of the first insulating layer 41, the second insulating layer 42, and the second insulating member 52. Specifically, the first insulating layer 41, the second insulating layer 42, and the second insulating member 52 are made of a resin material, and the first insulating member 51 is made of ceramic. For example, aluminum oxide (alumina) can be used as the ceramic constituting the first insulating member 51. In other words, in a cross-sectional view taken along a plane perpendicular to the extension direction of the flat wire 12a, the laminated structure of the metal layer 31 and the thermally conductive layer 32 is not entirely covered with ceramic, but is partially covered with ceramic. The first insulating member 51 may be made of a ceramic other than aluminum oxide.

[0065] As described above, the first insulating member 51 is made of an inorganic material such as ceramic having high thermal conductivity, and the first insulating layer 41, the second insulating layer 42, and the second insulating member 52 are made of a resin material. This structure can be formed, for example, by the sheet AM method or the multi-material AM method. With this structure, heat generated in the laminated structure of the winding structure 1 can be efficiently dissipated to the teeth 11 a via the first insulating member 51, which has a relatively high thermal conductivity.

[0066] Alternatively, the first insulating layer 41, the second insulating layer 42, and the first insulating member 51 may be made of an inorganic material such as ceramic having high thermal conductivity, and only the second insulating member 52 may be made of a resin material. With this structure, heat can be efficiently dissipated to the yoke 11b in addition to the teeth 11a.

[0067] The laminated structure of the metal layer 31 and the heat conduction layer 32 may be covered entirely with ceramic.

[0068] As described above, the winding coil 12 according to this embodiment is a winding structure in which the flat wire 12a is wound, and the flat wire 12a has a laminated structure in which a metal layer 31 and a heat conduction layer 32 having a higher thermal conductivity than the metal layer 31 are laminated in the thickness direction of the flat wire 12a.

[0069] With this configuration, the transfer of heat generated mainly in the metal layer 31, through which current flows, is promoted by the thermally conductive layer 32, allowing for efficient heat conduction in a direction perpendicular to the direction in which the flat wires 12a extend (i.e., the direction in which current flows). In other words, the thermal conductivity in the perpendicular direction, i.e., the thickness direction of the flat wires 12a, can be improved. As a result, even if heat is generated from the flat wires 12a that constitute the winding coil 12 due to current flowing through the flat wires 12a, the heat can be efficiently dissipated to the outside of the flat wires 12a (to the teeth 11a). This means that heat is prevented from building up inside the winding coil 12. Therefore, a winding coil 12 with excellent heat dissipation properties can be achieved, despite its high space factor.

[0070] In the winding coil 12 according to this embodiment, the metal layers 31 and the heat conduction layers 32 are alternately stacked one on top of the other.

[0071] This configuration allows the heat generated in the flat wire 12a to be dissipated more efficiently.

[0072] In particular, in the winding coil 12 of this embodiment, both sides of the laminated structure of the metal layer 31 and the thermally conductive layer 32 are covered with a pair of thermally conductive layers 32. This allows the heat generated in the flat wire 12a to be efficiently dissipated to the outside of the flat wire 12a.

[0073] In the winding coil 12 according to this embodiment, the metal layer 31 is made of copper.

[0074] In this way, by constructing the metal layer 31 using copper, which has a relatively low resistance among metal materials, the heat generated in the flat wire 12a can be dissipated by the thermal conduction layer 32, while the metal layer 31 can efficiently pass current.

[0075] In the winding coil 12 according to this embodiment, the heat conduction layer 32 is made of a graphite sheet.

[0076] In this way, by forming the thermally conductive layer 32 from a graphite sheet having high thermal conductivity, the heat generated in the flat wire 12a can be efficiently dissipated.

[0077] In the winding coil 12 (winding structure) of the present embodiment, heat dissipation can be improved by alternately stacking multiple metal layers 31 and thermally conductive layers 32. However, the winding coil 12 of the present embodiment is not limited to this layered structure. For example, since heat dissipation is improved if the thermally conductive layer 32 is disposed inside or near the metal layer 31, the winding coil 12 may have only one thermally conductive layer 32. Alternatively, the winding coil 12 may have a structure including one thermally conductive layer 32 sandwiched between two metal layers 31, or one metal layer 31 may have a thermally conductive layer 32 inserted on either or both of its upper and lower surfaces (at the interface with the first insulating layer 41 or the second insulating layer 42). Thus, the layered structure of the winding coil 12 may have at least one thermally conductive layer 32 inserted in the thickness direction of the flat wires 12a.

[0078] In the winding coil 12 according to this embodiment, the thermally conductive layers 32 may be insulating thermally conductive sheets. Specifically, all of the thermally conductive layers 32 may be made of insulating graphite sheets.

[0079] In this way, since the thermal conduction layer 32 has insulating properties, it is possible to suppress eddy currents generated in the metal layer 31, thereby reducing high-frequency loss. This point will be explained using Figures 7A and 7B. Figure 7A is a cross-sectional perspective view of a conventional flat wire 12aX, which is a rectangular wire, and Figure 7B is a cross-sectional perspective view of the flat wire 12a according to the embodiment.

[0080] The flat wire 12aX shown in FIG. 7A has a structure in which a metal wire 31X made of simple copper is coated with an insulating film 41X. On the other hand, the flat wire 12a shown in FIG. 7B has a structure in which the metal wire 31X shown in FIG. 7A is divided into multiple metal layers 31 in the thickness direction, and multiple insulating thermally conductive layers 32 are inserted between the metal layers 31. This structure allows the eddy currents generated in the metal layers 31 of the flat wire 12a shown in FIG. 7B to be smaller than the eddy currents generated in the metal wire 31X of the flat wire 12aX shown in FIG. 7A. As a result, the flat wire 12a shown in FIG. 7B can reduce high-frequency loss compared to the flat wire 12aX shown in FIG. 7A. This effect of reducing high-frequency loss is particularly noticeable in high-speed rotating motors, etc.

[0081] In addition, the winding coil 12 according to this embodiment includes, in the thickness direction of the flat wire 12a, a first insulating layer 41 that covers one side of the laminated structure of the metal layer 31 and the heat conduction layer 32, and a second insulating layer 42 that covers the other side of the laminated structure of the metal layer 31 and the heat conduction layer 32.

[0082] In this way, both sides of the laminated structure of the metal layer 31 and the heat conduction layer 32 (both sides in the thickness direction of the flat wire 12a) are covered with the first insulating layer 41 and the second insulating layer 42, respectively, so that both sides in the thickness direction of the flat wire 12a can be insulated. This allows the flat wire 12a to be insulated for each turn of the winding coil 12.

[0083] In addition, the winding coil 12 according to this embodiment further includes a first insulating member 51 that covers the inner side surface of the laminated structure of the metal layer 31 and the heat conduction layer 32, and a second insulating member 52 that covers the outer side surface of the laminated structure of the metal layer 31 and the heat conduction layer 32.

[0084] In this way, by covering both sides of the laminated structure of the metal layer 31 and the thermal conduction layer 32 with the first insulating member 51 and the second insulating member 52, not only can both sides of the flat wire 12a in the thickness direction be insulated, but both sides can also be insulated.

[0085] Furthermore, in the winding coil 12 according to this embodiment, the first insulating member 51, the first insulating layer 41, the second insulating layer 42, and the second insulating member 52 may be made of different insulating materials. Specifically, the first insulating member 51 on the inner circumferential side (i.e., the tooth 11a side) of the laminated structure of the metal layer 31 and the thermally conductive layer 32 may be made of a material having a higher thermal conductivity than the other insulating layers and insulating members. In other words, the thermal conductivity of the first insulating member 51 may be higher than the thermal conductivity of the first insulating layer 41, the second insulating layer 42, and the second insulating member 52.

[0086] With this configuration, the heat generated in the flat wire 12a can be efficiently conducted to the teeth 11a, and therefore the heat generated in the flat wire 12a can be efficiently dissipated.

[0087] In this case, in the winding coil 12 according to this embodiment, the first insulating member 51 is made of ceramic, and the first insulating layer 41, the second insulating layer 42, and the second insulating member 52 are made of resin material. The thermal conductivity of ceramic is several tens of times higher than that of resin material. Therefore, by making the first insulating member 51 on the tooth 11a side of ceramic, heat generated in the flat wire 12a can be efficiently conducted to the tooth 11a (stator core 11).

[0088] Furthermore, as described above, the laminated structure of the metal layer 31 and the heat conduction layer 32 is not entirely covered with ceramic in a cross section taken along a plane perpendicular to the extension direction of the flat wire 12a, but is only partially covered with ceramic. This configuration prevents the insulating material from peeling off from the laminated structure of the metal layer 31 and the heat conduction layer 32, and allows the heat generated in the flat wire 12a to be efficiently conducted to the teeth 11a. This point will be described in detail below.

[0089] When viewed in cross section at a plane perpendicular to the extension direction of the flat wire 12a, if the entire peripheral surface of the laminated structure of the metal layer 31 and the heat conduction layer 32 is covered with a resin material, the thermal conductivity of the resin material is low, so even if the heat conduction layer 32, which has a high thermal conductivity, can move the heat generated in the flat wire 12a inward to the vicinity of the teeth 11a, the thermal resistance of the resin material may prevent the heat generated in the flat wire 12a (flat wire) from being smoothly conducted to the teeth 11a.

[0090] On the other hand, in a cross-sectional view taken along a plane perpendicular to the extension direction of the flat wire 12a, by covering the entire peripheral surface of the laminated structure of the metal layer 31 and the heat conduction layer 32 with ceramic, the high thermal conductivity of ceramic allows the heat generated in the flat wire 12a to be smoothly conducted to the teeth 11a. However, because the thermal expansion coefficients of the metal material constituting the metal layer 31 and the ceramic are significantly different (i.e., the difference in thermal expansion coefficients is large), there is a risk that the ceramic will peel off from the metal layer 31 due to the thermal expansion between the metal layer 31 and the ceramic.

[0091] Therefore, in the winding coil 12 of this embodiment, in a cross section taken along a plane perpendicular to the extension direction of the flat wire 12a, the entire periphery of the laminated structure of the metal layer 31 and the thermally conductive layer 32 is not covered with ceramic, but the laminated structure of the metal layer 31 and the thermally conductive layer 32 is only partially covered with ceramic. In particular, the first insulating member 51, which serves as a heat path to the teeth 11a, is made of ceramic. With this configuration, the insulating material does not peel off from the laminated structure of the metal layer 31 and the thermally conductive layer 32, and heat generated in the flat wire 12a can be efficiently conducted to the teeth 11a.

[0092] In addition, methods for forming partially different insulating members include, for example, the multi-material AM method and the sheet AM method. In addition, with the conventional dip forming method, it is possible to coat the winding coil 12 with the same insulating material, but it is considered difficult to form different insulating materials.

[0093] A simulation was carried out to confirm the heat dissipation properties of the winding coil 12 according to the embodiment, and the results of the simulation will be described below.

[0094] This simulation was carried out based on the cross-sectional structure shown in Fig. 4. Fig. 8A shows a partial cross-sectional structure of an electric motor 100X equipped with winding coils 12X of comparative examples 1 and 2, and Fig. 8B shows a cross-sectional structure of an electric motor 100 equipped with winding coils 12 of examples 1, 2, and 3.

[0095] 8A, the winding coil 12X of Comparative Examples 1 and 2 has a configuration in which no thermally conductive layer is inserted between the metal layers 31, and insulating layers 40 are present between the metal layers 31. Specifically, seven metal layers 31 are each surrounded by an insulating layer 40. A first insulating layer 41 is formed on the topmost metal layer 31, and a second insulating layer 42 is formed below the bottommost metal layer 31. The insulating layer 40 can be made of the same material as the first insulating layer 41 or the second insulating layer 42.

[0096] 8B, the metal layer 31 is divided and a thermally conductive layer 32 is inserted in the center. That is, in the winding coils 12 of Examples 1, 2, and 3, the thermally conductive layer 32 is inserted between the metal layers 31. Otherwise, the cross-sectional structure of the winding coils 12 of Examples 1, 2, and 3 is the same as that of the winding coils 12X of Comparative Examples 1 and 2. Therefore, if a laminate structure having two metal layers 31 and a thermally conductive layer 32 inserted between them is considered to be one laminate structure, seven such laminate structures are provided, and each of the seven laminate structures is surrounded by an insulating layer 40.

[0097] 8A and 8B, the width of each flat wire 12a (rectangular wire) was set to a constant (5 mm), the thicknesses of the first insulating layer 41, the second insulating layer 42, the insulating layer 40, the first insulating member 51, and the second insulating member 52 were set to 0.2 mm, and the thicknesses of the metal layer 31 (copper layer) and the heat conduction layer 32 were set to 1.3 mm and 0.2 mm, respectively. The rated output of the electric motor 100 was assumed to be 300 W, and the heat quantity of the flat wire 12a was set so that the loss generated in the entire winding coil 12 was 35 W.

[0098] For the winding coils 12X of Comparative Examples 1 and 2 and the winding coils 12 of Examples 1, 2, and 3 configured in this manner, a simulation was performed to determine the state in which heat generated in the flat wire 12a is dissipated into the air layer, teeth 11a, and yoke 11b (each set to 25°C), and the temperature of each part was determined.

[0099] The simulation results are shown in Figures 9 to 11C. Figure 9 shows the maximum and average temperatures at each location for the winding coil 12X of Comparative Examples 1 and 2 and the winding coil 12 of Examples 1, 2, and 3. Figure 10A is a temperature contour diagram (Max 80°C, 50°C) when the winding coil 12X of Comparative Example 1 is used. Figure 10B is a temperature contour diagram (Max 80°C, 50°C) when the winding coil 12X of Comparative Example 2 is used. Figure 11A is a temperature contour diagram (Max 50°C) when the winding coil 12 of Example 1 is used. Figure 11B is a temperature contour diagram (Max 50°C) when the winding coil 12 of Example 2 is used. Figure 11C is a temperature contour diagram (Max 50°C) when the winding coil 12 of Example 3 is used.

[0100] 9 also shows the materials of the insulators (first insulating layer 41, second insulating layer 42, first insulating member 51, second insulating member 52) for the winding coil 12X of Comparative Examples 1 and 2 and the winding coil 12 of Examples 1, 2, and 3. In FIG. 9, "resin" is polyester.

[0101] As shown in FIG. 9, the winding coil 12X of the first comparative example is made of a rectangular copper wire and a resin insulator.

[0102] The winding coil 12X of Comparative Example 2 is composed of a copper flat wire and an insulator made of an alumina ceramic material (all ceramic materials). Note that ceramic materials have a higher thermal conductivity than resin, so Comparative Example 2 is expected to have improved heat dissipation characteristics compared to Comparative Example 1. However, in reality, there are many challenges in achieving the structure of Comparative Example 2. This is because the compatibility between copper and ceramic (difference in thermal expansion coefficients) can cause the flat wire (copper layer) and the ceramic layer to peel off from each other.

[0103] The wound coil 12 of Example 1 has a structure in which one thermally conductive layer 32 (t=0.2 mm) is inserted in the center of the metal layer 31. The insulators of Example 1 (first insulating layer 41, second insulating layer 42, first insulating member 51, second insulating member 52) are all made of resin, as in Comparative Example 1.

[0104] The winding coil 12 of Example 2 has the same cross-sectional structure as Example 1, but the insulating material is different. Specifically, in Example 2, only the first insulating member 51 in contact with the teeth 11a is made of a ceramic material (alumina), and the other insulators (first insulating layer 41, second insulating layer 42, second insulating member 52) are made of resin. As described above, the structure of Example 2 uses a ceramic material only in some parts, which reduces the problems of Comparative Example 2 or Example 3 described below. Furthermore, the winding coil 12 of Example 2 can be formed by a multi-material AM method, including a sheet AM method.

[0105] The winding coil 12 of Example 3 has the same cross-sectional structure as Example 1, but the insulating material is different. Specifically, in Example 3, the insulators (first insulating layer 41, second insulating layer 42, first insulating member 51, second insulating member 52) are all made of a ceramic material made of alumina.

[0106] The simulation results (temperature) shown in FIG. 9 reveal that the temperature in Comparative Example 1 was the highest, with the temperature inside the metal layer (copper layer) exceeding 60°C.

[0107] Also, as can be seen from Figure 10A, when the winding coil 12X of Comparative Example 1 is used, heat cannot be diffused effectively to the teeth 11a and yoke 11b, and there are parts of the winding coil 12X where the temperature reaches 70°C or higher.

[0108] On the other hand, as shown in Figure 9, the winding coil 12X of Comparative Example 2 uses alumina, which has high thermal conductivity, as the insulating material instead of resin, and therefore it is possible to significantly reduce the temperature of the winding coil 12 compared to Comparative Example 1. In fact, a comparison of the temperature contour diagram of Comparative Example 2 shown in Figure 10B with the temperature contour diagram of Comparative Example 1 shown in Figure 10B reveals that heat diffusion to the yoke 11b is improved. However, as mentioned above, when copper and a ceramic material (alumina) are used, there is a risk of peeling between the copper layer and the ceramic layer, which presents challenges in realizing this.

[0109] Looking again at the results in Figure 9, it can be seen that in the winding coils 12 of Examples 1, 2, and 3, by inserting the thermal conduction layers 32 between the metal layers 31, the heat dissipation characteristics are significantly improved compared to the winding coil 12X of Comparative Example 1.

[0110] In fact, as shown in Figures 11A to 11C, there is a clear difference in the heat dissipation characteristics between the winding coil 12 of Examples 1, 2, and 3, in which the thermally conductive layer 32 is introduced between the metal layers 31, and the heat dissipation characteristics of the winding coil 12X of Comparative Examples 1 and 2.

[0111] Furthermore, as shown in FIG. 10B, in Comparative Example 2 in which ceramic (alumina) was used as the insulating material, the thermal resistance of the ceramic was reduced, resulting in improved thermal diffusion from the winding coil 12X to the yoke 11b. On the other hand, as shown in FIG. 11A, in Example 1 in which the thermal conduction layer 32 was inserted, there was almost no improvement in thermal diffusion to the yoke 11b, and the temperature of the winding coil 12 was reduced due to improved thermal diffusion in the in-plane direction of the flat wires 12a.

[0112] 11B, in the winding coil 12 of Example 2, it can be seen that further temperature reduction can be achieved by using ceramic (alumina) for only the first insulating member 51 that contacts the teeth 11 a. As can be seen from comparing Figure 11B with Figure 10B, in Example 2, the temperature in the area close to the teeth 11 a is reduced rapidly, confirming that the structure of Example 2 is extremely effective in reducing temperature.

[0113] Furthermore, as shown in FIG. 11C, the winding coil 12 of Example 3 exhibits the highest thermal diffusion effect and has an excellent heat dissipation effect.

[0114] It was also confirmed that the winding coil 12 of Examples 1, 2, and 3 had the same heat dissipation effect as the winding coil 12X of Comparative Example 2. In other words, it was confirmed that the winding coil 12 of Example 1, by inserting one thermally conductive layer 32, could obtain heat dissipation characteristics almost equivalent to those of the winding coil 12X of Comparative Example 2, even when using an insulating resin material that is easy to form.

[0115] (Modifications) The winding structure, the electric motor, and the method for manufacturing the winding structure according to the present disclosure have been described above based on the embodiments, but the present disclosure is not limited to the above-described embodiments.

[0116] For example, in the above embodiment, each of the multiple thermally conductive layers 32 is a single layer, consisting of only one layer along the extension direction of the flat wire 12a. However, this is not limited to this. Fig. 12A is a cross-sectional perspective view of the flat wire 12aA constituting the winding coil 12A, and Fig. 12B is an exploded perspective view of the flat wire 12aA constituting the winding coil 12A. Also, Figs. 12A and 12B omit the first insulating member 51 and the second insulating member 52. For example, as with the flat wire 12aA shown in Figs. 12A and 12B, each of the multiple thermally conductive layers 32A may be divided into multiple parts along the extension direction of the flat wire 12a. In other words, the thermally conductive layer 32A does not need to cover the entire surface of the metal layer 31.

[0117] 12A and 12B , because the thermally conductive layer 32A is divided into multiple pieces, there are areas on the surface of the metal layer 31 where the thermally conductive layer 32A is not present. As a result, the two metal layers 31 sandwiching the divided thermally conductive layer 32A come into contact with each other in areas where the thermally conductive layer 32A is not present. In other words, the metal layers 31 are in partial contact with each other. This prevents a decrease in adhesion between the thermally conductive layer 32A and the metal layer 31, which are made of different materials, and prevents voids from occurring at the interface between the thermally conductive layer 32A and the metal layer 31.

[0118] 12A and 12B , the thermally conductive layer 32A in contact with the first insulating layer 41 is divided, and the thermally conductive layer 32A in contact with the second insulating layer 42 is also divided. This results in partial adhesion between the first insulating layer 41 and the metal layer 31, and partial adhesion between the second insulating layer 42 and the metal layer 31. This improves the adhesion between the first insulating layer 41 and the second insulating layer 42 and the metal layer 31, thereby preventing peeling between the first insulating layer 41 and the second insulating layer 42 and the metal layer 31 and preventing voids from occurring at the interface between the first insulating layer 41 and the second insulating layer 42 and the metal layer 31.

[0119] 12A and 12B, all of the thermally conductive layers 32 are divided, but this is not limiting. That is, it is sufficient that at least one of the multiple thermally conductive layers 32 is divided into multiple parts along the extension direction of the flat line 12a.

[0120] In the above embodiment, the first insulating layer 41 and the second insulating layer 42 are made of the same insulating material. However, this is not limited to this. For example, as in the winding coil 12B shown in FIG. 13, the first insulating layer 41 and the second insulating layer 42B may be made of different materials. FIG. 13 is a cross-sectional view showing the winding coil 12B according to Modification 2 mounted on a stator. In this case, the thermal conductivity of the second insulating layer 42B located on the base side (the yoke 11b side) of the tooth 11a may be higher than that of the first insulating layer 41. For example, if the first insulating layer 41 is made of a resin material, the second insulating layer 42B can be made of ceramic to increase the thermal conductivity of the second insulating layer 42B higher than that of the first insulating layer 41. This configuration allows heat generated in the flat wire 12aB to be efficiently conducted not only from the first insulating member 51 to the tooth 11a but also from the second insulating layer 42B to the yoke 11b. In other words, the heat generated in the flat wire 12aB can be efficiently conducted to the stator core 11. This allows the heat generated in the flat wire 12aB to be more efficiently dissipated. In Fig. 13, only the second insulating layer 42B of the flat wire 12aB of the turn closest to the yoke 11b of the winding coil 12B is made of ceramic, but this is not limitative.

[0121] In the above embodiment, the laminated structure of the metal layer 31 and the heat conduction layer 32 in the flat wire 12a constituting the winding coil 12 is entirely surrounded by insulating material, that is, the first insulating layer 41, the second insulating layer 42 and the first insulating member 51, the second insulating member 52. Therefore, the winding coil 12 is attached to the teeth 11a of the stator core 11 without an insulating frame (coil bobbin). However, this is not limiting. The winding coil 12 may also be attached to the teeth 11a of the stator core 11 via an insulating frame.

[0122] 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.

[0123] 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 of slots in the stator 10 and any number of magnetic poles in the rotor 20 can be applied.

[0124] In the above embodiment, the rotor 20 is an IPM rotor, but this is not limiting. For example, if a permanent magnet rotor is used as the rotor 20, a surface permanent magnet rotor (SPM rotor) in which multiple permanent magnets are provided on the outer surface of the rotor core may be used. The winding structure of the present disclosure can also be applied to a reluctance motor that does not use permanent magnets.

[0125] In the above embodiment, the electric motor 100 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 winding coil 12 may be a generator. In addition, the winding structure of the present disclosure is used as the winding coil 12 of the stator 10, but the present invention is not limited thereto and may be used as the winding coil 12 of a component other than a stator.

[0126] The winding structure of the present disclosure is not limited to use in the electric motor 100, but may also be used in a generator. The winding structure of the present disclosure may also be used as a transformer, an inductor, a power choke coil, or the like.

[0127] In addition, the present disclosure also includes forms obtained by applying various modifications to the above-mentioned embodiments that would occur to a person skilled in the art, and forms realized by arbitrarily combining the components and functions of the above-mentioned embodiments within the scope of the present disclosure. Furthermore, the present disclosure also includes any combination of one or more components of each of the multiple claims described in the claims at the time of filing with the components of other claims. Furthermore, when a dependent claim described in the claims at the time of filing is made into a multiple claim or multiple multiple claim that cites any multiple claims (for example, when a multiple claim or multiple multiple claim that cites all of the parent claims of each claim), all forms obtained by combining all of the claims included in that multiple claim or multiple multiple claim are also included in the present disclosure.

[0128] The winding structure, electric motor, and method for manufacturing a winding structure according to the present disclosure can be widely used in a variety of products, including rotating electrical machines such as electric motors, as well as passive elements such as magnetic devices such as inductors or transformers. In this way, the winding structure, electric motor, and method for manufacturing a winding structure according to the present disclosure are industrially useful.

[0129] REFERENCE SIGNS LIST 10 stator 11 stator core 11a teeth 11b yoke 11c slot 12, 12A, 12B, 12X winding coil 12a, 12aA, 12aB, 12aX flat wire 20 rotor 21 rotor core 22 permanent magnet 23 rotating shaft 31 metal layer 32, 32A heat conduction layer 40 insulating layer 41 first insulating layer 42, 42B second insulating layer 51 first insulating member 52 second insulating member 100, 100X electric motor

Claims

1. A winding structure in which a flat wire is wound, wherein the flat wire has a laminated structure formed by laminating metal layers in the thickness direction of the flat wire, and at least one heat conduction layer having a higher thermal conductivity than the metal layer is inserted in the thickness direction of the flat wire in the laminated structure.

2. The winding structure according to claim 1, wherein a plurality of the metal layers and the heat conduction layers are alternately laminated one by one.

3. The winding structure according to claim 2, wherein the metal layer is made of copper.

4. The winding structure according to claim 2, wherein the heat conduction layer is made of a graphite sheet.

5. The winding structure according to any one of claims 1 to 4, wherein the heat conduction layer has insulation properties.

6. The winding structure according to any one of claims 1 to 4, further comprising a first insulating layer covering a first laminated surface which is one of a pair of laminated surfaces of the laminated structure, and a second insulating layer covering a second laminated surface which is the other of the pair of laminated surfaces of the laminated structure.

7. The winding structure according to claim 6, further comprising a first insulating member covering a side surface on the inner peripheral side of the laminated structure, and a second insulating member covering a side surface on the outer peripheral side of the laminated structure.

8. The insulating material constituting the first insulating member is different from the insulating materials constituting the first insulating layer, the second insulating layer, and the second insulating member. The winding structure according to claim 7.

9. The thermal conductivity of the first insulating member is higher than the thermal conductivities of the first insulating layer, the second insulating layer, and the second insulating member. The winding structure according to claim 8.

10. The first insulating member is made of ceramic, and the first insulating layer, the second insulating layer, and the second insulating member are made of a resin material. The winding structure according to claim 8.

11. The insulating materials constituting the first insulating member, the first insulating layer, and the second insulating layer are the same, and the insulating material constituting the second insulating member is different from the insulating materials constituting the first insulating member, the first insulating layer, and the second insulating layer. The winding structure according to claim 7.

12. The thermal conductivity of the second insulating member is lower than the thermal conductivities of the first insulating layer, the second insulating layer, and the first insulating member. The winding structure according to claim 11.

13. The winding structure according to claim 12, wherein the first insulating layer, the second insulating layer, and the first insulating member are made of ceramic.

14. At least one of the plurality of heat conduction layers is divided into a plurality along the extending direction of the flat wire, and two metal layers sandwiching the divided heat conduction layer among the plurality of metal layers are in contact with each other at a location where the heat conduction layer does not exist. The winding structure according to any one of claims 1 to 4.

15. An electric motor comprising a stator and a rotor that rotates by the magnetic force of the stator, wherein the stator has a stator core having a plurality of teeth and a winding coil wound around the plurality of teeth, and the winding coil is the winding structure according to any one of claims 1 to 4.

16. A method for manufacturing the winding structure according to any one of claims 1 to 4, the method including a step of forming the laminated structure in the winding structure by a sheet AM (Additive Manufacturing) method.

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