Winding of an electromagnetic component, stator of a rotating electric machine, rotating electric machine and wheel

Abstract

The objective of this invention is to provide a winding of an electromagnetic component, a stator of a rotary motor, a rotary motor, and a wheel that can improve the connection quality of the coil ends and simplify the assembly process. The winding of the electromagnetic component includes a first conductor (3) and a second conductor (4) electrically connected to the first conductor (3). The first conductor (3) and the second conductor (4) are fixed within the electromagnetic component. At least one of the first conductor (3) and the second conductor (4) has a bend (10). The first conductor (3) is pressed into close contact with the second conductor (4) by a restoring force (12) caused by the residual stress of the bend (10).

Description

Technical Field

[0001] This invention relates to windings of electromagnetic components, stators of rotary motors, rotary motors, and wheels. Background Technology

[0002] In the drive motors of xEVs (electric vehicles: electric vehicles, plug-in hybrid vehicles, hybrid vehicles, hydrogen fuel cell vehicles, etc.), high torque is required, necessitating the flow of large currents in the motor windings. Therefore, square wires, which increase slot occupancy and suppress conductor resistance, are used to reduce copper losses.

[0003] In the coil end forming process, segmented coils are inserted into stator slots and then welded or soldered. However, there are concerns that insufficient pressure between the coils during welding may lead to poor welding, and in dissimilar metal joining such as soldering, there are concerns that the heat during melting may cause the coil bending portion to deform due to residual stress, resulting in poor joining. Therefore, the coils are pressed together by riveting (for example, see Patent Document 1) or clamps.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2001-037131 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] The technology disclosed in Patent Document 1 can improve the bonding quality of the coil ends. However, it increases the number of parts and the workload, thus failing to simplify the assembly process.

[0009] The purpose of this invention is to provide an electromagnetic component winding, a stator of a rotary motor, a rotary motor, and a wheel that can improve the connection quality of the coil ends and simplify the assembly process.

[0010] Technical solutions for solving the problem

[0011] To achieve the above objectives, the present invention includes a first conductor and a second conductor electrically connected to the first conductor, the first conductor and the second conductor being fixed within an electromagnetic component, at least one of the first conductor and the second conductor having a bend, the first conductor being pressurized by a restoring force caused by the residual stress of the bend and thus in close contact with the second conductor.

[0012] Invention Effects

[0013] According to the present invention, the bonding quality of the coil ends can be improved, while the assembly process is simplified. Other issues, structures, and effects not described above will be explained through the following description of embodiments. Attached Figure Description

[0014] Figure 1 This is a perspective view of the main part of the electromagnetic component including the winding in this embodiment.

[0015] Figure 2 This is a diagram showing the segmented coils (first conductor) and segmented coils (second conductor) that make up the windings, viewed from the axial direction of the electric motor (rotating motor).

[0016] Figure 3A This is a diagram illustrating an example where the shape of a curved section is an arc.

[0017] Figure 3B This is a diagram illustrating an example of a curved section with an inverted V-shape.

[0018] Figure 4A This is a diagram illustrating resilience.

[0019] Figure 4B This is a diagram illustrating the clamping force.

[0020] Figure 5 This is an enlarged view of the curved section.

[0021] Figure 6A It is a diagram used to illustrate the positional relationship of multiple segmented coils.

[0022] Figure 6B Viewed from the axial direction Figure 6A The diagram shows multiple segmented coils.

[0023] Figure 7 This is a diagram used to illustrate two curved sections.

[0024] Figure 8 This is a diagram illustrating the magnitude relationship of residual stress.

[0025] Figure 9 This is an explanatory diagram showing the relative positions of the two bends.

[0026] Figure 10 This is an explanatory diagram showing the relative positions of the two bends.

[0027] Figure 11 This is an illustration of the positional relationship of multiple segmented coils.

[0028] Figure 12A This is an illustration of the positional relationship of multiple segmented coils.

[0029] Figure 12B It is a magnified 3D view of a portion of the stator, showing the positional relationship of multiple segmented coils.

[0030] Figure 13This is an illustration of the positional relationship of multiple segmented coils.

[0031] Figure 14 This is an illustration of the positional relationship of multiple segmented coils.

[0032] Figure 15 This is an explanatory diagram of the circumferential length of the insertion part.

[0033] Figure 16 This diagram shows that the curved part is approximately parallel to the axis of rotation.

[0034] Figure 17 This is an illustration of welding.

[0035] Figure 18A This diagram illustrates the manufacturing process of a coil, showing the stamping of a sheet metal.

[0036] Figure 18B This diagram illustrates the manufacturing process of a coil, showing the bending of a flat electromagnetic wire.

[0037] Figure 19 This is a perspective view of a wheel including an electric motor (rotary motor) using windings according to this embodiment. Detailed Implementation

[0038] The structure of the winding in this embodiment will be described below using the accompanying drawings. The winding is used in electromagnetic components such as transformers, generators, and motors. Furthermore, in each figure, the same reference numeral denotes the same part.

[0039] First, use Figure 1 Explain the structure around winding 15. Figure 1 This is a perspective view showing the main part of the electromagnetic component including the winding 15 in this embodiment. Figure 1 In this example, the electromagnetic component is the stator 14 of the electric motor (rotating machine). The stator 14 includes a stator core 2 (core) and windings 15. The windings 15 include segmented coils 3 (first conductors) and segmented coils 4 (second conductors).

[0040] (Structure of the winding) Figure 2 This is a diagram showing the segmented coil 3 (first conductor) and segmented coil 4 (second conductor) constituting the winding 15, viewed from the axial direction of the electric motor (rotating motor).

[0041] In the stator (electromagnetic component), segmented coil 3 (first conductor) and segmented coil 4 (second conductor) are electrically connected. Segmented coil 3 (first conductor) and segmented coil 4 (second conductor) are fixed inside the stator (electromagnetic component). At least one of segmented coil 3 (first conductor) and segmented coil 4 (second conductor) has a bend 10.

[0042] The residual stress in the bent portion 10 creates a restoring force 12, which applies pressure to bring the connecting portion 6 of the segmented coil 3 (first conductor) into close contact with the insertion portion 11 of the segmented coil 4 (second conductor). As a result, the clamping force 13 is transmitted from the segmented coil 3 (first conductor) to the segmented coil 4 (second conductor) via the connecting surface 9.

[0043] In the bent portion 10, there is a residual stress σ1 in the direction that presses the connecting portion 6 toward the segmented coil 4 (second conductor). When the temperature rises, a restoring force 12 is generated in the direction that deforms to release the residual stress σ1. Therefore, due to the restoring force 12 caused by the residual stress σ1, the connecting portion 6 of the segmented coil 3 (first conductor) is pressed against the insertion portion 11 of the segmented coil 4 (second conductor).

[0044] Furthermore, the segmented coil 3 (first conductor) has an intermediate portion 7 (first intermediate portion) between the bent portion 10 and the insertion portion 5, and an intermediate portion 8 (second intermediate portion) between the bent portion 10 and the connecting portion 6. The insertion portion 5 of the segmented coil 3 (first conductor) is fixed inside the stator (electromagnetic component).

[0045] The connecting surface 9 is the surface that electrically connects the segmented coil 3 (first conductor) and the segmented coil 4 (second conductor). The segmented coil 3 (first conductor) and the segmented coil 4 (second conductor) are manufactured with the goal of non-interference and non-separation of dimensions, and the connecting part 6 is pressed against the insertion part 11 by the restoring force 12.

[0046] The bending portion 10 can be bent from the flat plate, and the bending radius (R) can be arbitrary. That is, it can also be an arc. Because of the restoring force caused by residual stress, the bending portion 10, which is closest to the insertion portion 5 (fixed portion) of the segmented coil 3 (first conductor), protrudes towards the segmented coil 4 (second conductor).

[0047] (Stator Structure) Stator of Rotary Electric Machine 14 Figure 1 As shown, it includes a stator core 2 (core) with slot 1 and multiple segmented coils 3 and 4 (coils) with rectangular cross-sections inserted into slot 1. The multiple segmented coils 3 (coils) are as follows... Figure 2 As shown, the device includes an insertion portion 5 in an insertion slot 1, a connecting portion 6 electrically connected to other segmented coils 4 (coils) among a plurality of segmented coils 3, 4 (coils), and an intermediate portion (whole) formed between the insertion portion 5 and the connecting portion 6. Furthermore, the intermediate portion (whole) includes an intermediate portion 7 (first intermediate portion) and an intermediate portion 8 (second intermediate portion).

[0048] On the connecting portion 6, a connecting surface 9 is formed that faces the other segmented coils 4 (coils) in the radial direction of the motor (rotary motor). The middle portion (whole) has at least one bend 10 when viewed from the direction of rotation axis (axial direction) of the motor (rotary motor). The bend 10 closest to the insertion portion 5 forms a protrusion on the side of the other segmented coils 4 (coils).

[0049] (Details of the structure) as follows Figure 3A As shown, the shape of the curved portion 10, viewed from the axial direction of the electric motor (rotary motor), can be an arc. Additionally, as... Figure 3B As shown, the shape of the bent portion 10 viewed from the axial direction of the electric motor (rotary motor) can also be a bend (inverted V-shape).

[0050] Figure 4A The restoring force 12 shown is a force that deforms in the direction of releasing the residual stress σ1 when the bent portion 10 is bent, and has the property of returning to straightness after time when heated or subjected to external force. Figure 4B The clamping force 13 shown is the force of the restoring force 12 caused by the residual stress σ1, which presses the connecting part 6 against the insertion part 11 of the segmented coil 4 (second conductor) with the bending part 10 as the fulcrum.

[0051] When the convex shape of the bent portion 10 is to be restored to its original flat shape before bending due to the restoring force 12 caused by residual stress σ1, the connecting portion 6 is pressed against the insertion portion 11, making welding and other fusion bonding easier. Poor bonding is prone to occur when the welded portions are not in close contact. The bent portion 10 must protrude towards the insertion portion 11 of the segmented coil 4 (second conductor).

[0052] Figure 4A The intermediate portion 7 (first intermediate portion) shown is located between the insertion portion 5 and the bending portion 10 and does not move. The intermediate portion 8 (second intermediate portion) is located between the bending portion 10 and the connecting portion 6, and moves together with the connecting portion 6 toward the insertion portion 11 of the segmented coil 4 (second conductor).

[0053] Figure 5 This is an enlarged view of the bent section 10. Tensile stress is generated on the outer side of the bend in the bent section 10. The stress is greater towards the outer side, which is a region of plastic deformation, and there is also an elastic region near the mid-face. Because it is stretched, it has the property of contraction. Compressive stress is generated on the inner side of the bend in the bent section 10. The stress is greater towards the inner side, which is a region of plastic deformation, and there is also an elastic region near the mid-face. Because it is flattened, it has the property of elongation. The mid-face is the surface where the stress is zero when the tensile and compressive stresses switch. In reality, there is a tendency for insufficient material on the outer side and an excess material on the inner side. Therefore, the stronger the bend (the greater the plate thickness and the smaller the bending radius R), the more the mid-face moves inward compared to the center of the plate thickness.

[0054] like Figure 6A , Figure 6B As shown, the stator 14 of the electric motor (rotary motor) includes a plurality of segmented coils, including a segmented coil 3 (first coil) that can be inserted into slot 1 (first slot) and a segmented coil 4 (second coil) that can be inserted into slot 1 (second slot) which is adjacent to slot 1 (first slot) in the circumferential direction.

[0055] The bent portion 10 is formed at a position that is equidistant from the insertion portion 5 of the segmented coil 3 (first coil) and the insertion portion 11 of the segmented coil 4 (second coil), or closer to the insertion portion 5 of the segmented coil 3 (first coil) than to the insertion portion 11 of the segmented coil 4 (second coil).

[0056] Because the bent portion 10 acts as a fulcrum for the rotating movement of the connecting portion 6, a longer arm length L2 allows for a smaller rotation angle to ensure the amount of movement of the connecting portion 6. Furthermore, if the gap between the connecting portion 6 and the segmented coil 4 (second coil) is the same, a shorter arm length L2 results in a larger rotation angle, causing the connecting portion 6 to tilt and making it difficult for the connecting surface 9 to make face contact. This can easily lead to poor welding. Therefore, the arm length L2 is preferably longer, thus limiting it to L2 ≥ L1. However, there are still advantages outside this range.

[0057] Alternatively, the segmented coils of adjacent slots 1 of the stator core 2 can be connected, but if there is a bend, the connection can also skip slot 1. Figure 6A , 6B This is an example with one bend point, so it is not a connection on the same layer, but you can also set multiple bend points to connect the same layer.

[0058] like Figure 7 As shown, the multiple segmented coils (coils) include a segmented coil 3 (first coil) that can be inserted into slot 1 (first slot) and a segmented coil 4 (second coil) that can be inserted into slot 1 (second slot) which is circumferentially adjacent to slot 1 (first slot).

[0059] The bending portion includes a bending portion 10 (first bending portion) formed on one side near the insertion portion 5 of the segmented coil 3 (first coil) and having a shape that protrudes toward the side of the segmented coil 4 (second coil), and a bending portion 10 (second bending portion) formed on one side near the insertion portion 11 of the segmented coil 4 (second coil) and having a shape that protrudes toward the side opposite to the bending portion 10 (first bending portion).

[0060] Figure 8This is a diagram illustrating the magnitude relationship of residual stress. The conditions for increasing residual stress are as follows (i) to (iv): (i) The thinner the plate, the greater the stress. (ii) The greater the tensile strength of the material, the greater the stress. (iii) The larger the bending angle, the greater the stress. (iv) The larger the bending radius (R), the greater the stress.

[0061] When the connecting part 6 of the segmented coil 3 (first coil) is arranged on the inner periphery of the insertion part 11 of the segmented coil 4 (second coil), the following relationship holds.

[0062] The bending angle θ1 of the first bend is greater than the bending angle θ2 of the second bend.

[0063] The residual stress σ1 at the first bend is greater than the residual stress σ2 at the second bend.

[0064] When the insertion part 5 of the segmented coil 3 (first coil) is used as the fixing point, the difference between σ1 and σ2 leaves residual stress that causes the connecting part 6 of the segmented coil 3 (first coil) to deform in the outward direction. Because of this stress, the connecting part 6 of the segmented coil 3 (first coil) is pressed against the insertion part 11 of the segmented coil 4 (second coil).

[0065] like Figure 9 As shown, the bending portion 10 (first bending portion) and the bending portion 10 (second bending portion) are formed such that the distance L2 between these bending portions is greater than the distance L1 between the bending portion 10 (first bending portion) and the insertion portion 5 of the segmented coil 3 (first coil).

[0066] Because the curved portion 10 (first curved portion) acts as a fulcrum for the rotating movement of the connecting portion 6, a longer arm length L2 allows for a smaller rotation angle to ensure the amount of movement of the connecting portion 6. Furthermore, if the gap between the connecting portion 6 and the segmented coil 4 (second coil) is the same, a shorter arm length L2 results in a larger rotation angle, causing the connecting portion 6 to tilt and making it difficult for the connecting surface 9 to make face contact. This can easily lead to poor welding. Therefore, the arm length L2 is preferably longer, thus limiting it to L2 ≥ L1. However, there are still advantages outside this range.

[0067] like Figure 10 As shown, the bending portion 10 (first bending portion) and the bending portion 10 (second bending portion) are formed such that the distance L2 between these bending portions is greater than the distance L3 between the insertion portion 11 of the segmented coil 4 (second coil) and the bending portion 10 (second bending portion).

[0068] The bending portion 10 (first bending portion) deforms in the direction that brings the connecting portion 6 closer to the segmented coil 4 (second coil), and the bending portion 10 (second bending portion) protrudes in the opposite direction, deforming in the direction that moves the connecting portion 6 away from the segmented coil 4 (second coil).

[0069] It is preferable that the length L2+L3 of the arm of the bent portion 10 (first bent portion) is longer, and it is preferable that the length L3 of the arm of the bent portion 10 (second bent portion) is shorter. If it is longer, the deformation of the connecting portion 6 in the direction away from the segmented coil 4 (second coil) will increase. Therefore, the length L3 of the arm of the bent portion 10 (second bent portion) is preferably shorter, thus limiting it to L2≥L3. However, there are still advantages outside this range.

[0070] like Figures 11-14 As shown, the segmented coil 3 (first coil) has two or more bends 10 at different positions in the direction of the rotation axis of the motor (rotary motor). The segmented coil 3 (first coil) is inserted into the first layer of the first slot, and the segmented coil 4 (second coil) is inserted into the second slot. The winding 15 has a segmented coil 4_1 (third coil) inserted into the same second slot as the segmented coil 4 (second coil) and in a layer that is radially adjacent to the segmented coil 4 (second coil) in the motor (rotary motor).

[0071] The connecting part 6 of segmented coil 3 (first coil) and the insertion part 11_1 of segmented coil 4_1 (third coil) are located on the same layer and are arranged in... Figure 11 The rotation axis shown is located outwards.

[0072] When forming the connection portion 6 on the same layer, the conductor plate thickness must be machined to 1 / 2. However, if the bent portions 10 are offset axially and the connection portion 6 of the segmented coil 3 (first coil) and the insertion portion 11_1 of the segmented coil 4_1 (third coil) are arranged on the same layer, the radial dimension can be suppressed without machining the plate thickness to 1 / 2. However, the weakness is the increase in axial dimension.

[0073] Additionally, the second slot is for inserting segmented coil 4 (the second coil) and segmented coil 4_1 (the third coil). However, the second slot does not need to be adjacent to the first slot. The layer refers to the coil position within the slot. Figure 11 In the example, there are a total of 6 layers, from the first layer to the sixth layer.

[0074] like Figure 15 As shown, the end face of the joint is formed in a direction substantially perpendicular to the rotation axis of the electric motor (rotary motor). The circumferential length of the connecting portion 6 of the segmented coil 3 (first coil) is longer than the circumferential length of the insertion portion 11 of the segmented coil 4 (second coil).

[0075] If the end face of the joint is perpendicular to the rotation axis, and the circumferential length of the connecting portion 6 of the segmented coil 3 (first coil) is longer than that of the insertion portion 11 (fixed in the slot) of the segmented coil 4 (second coil), then the joint can be secured even if the connecting portions 6 of the segmented coil 3 (first coil) are offset circumferentially. This allows for the absorption of component tolerances and assembly tolerances.

[0076] Furthermore, the coils of an electric motor (rotary motor) are typically multi-layered (wound in multiple turns) radially. The inner and outer coils have different circumferences, resulting in differences in the distance between the coils and necessitating the use of different components. In this embodiment, if the length difference is greater than the circumference difference, the same component can be used. This helps reduce the number of molds and lower costs due to the increased batch production effect caused by the increased number of identical components.

[0077] like Figure 16 As shown, the bent portion 10 is configured to be approximately parallel to the rotation axis. If a structure is adopted that bends parallel to the rotation axis, the insertion portion 11 of the segmented coil 4 (second coil) and the connecting portion 6 of the segmented coil 3 (first coil) can be made to be in simple parallel and surface contact.

[0078] Even if it is bent at an angle relative to the axis of rotation, it can still make surface contact, but it will become a 3D (three-dimensional) twisted shape, thus increasing the difficulty of manufacturing.

[0079] If the joint has good ground contact, the weld joint quality is improved, and it can also handle dissimilar metal joints such as soft brazing and hard brazing, in addition to welding.

[0080] like Figure 17 As shown, segmented coil 3 (first coil) and segmented coil 4 (second coil) are fixed, for example, by beam welding. Beam welding is a high-energy-density welding method such as electron beam welding (EBW) and laser welding. Because it allows for deep penetration with a narrower width, even flat-section coils can be welded from the side. Because it allows for point-like heating and melting, deformation is relatively small, and even thin plates can be welded.

[0081] Alternatively, arc welding such as TIG welding, beam welding such as EBW, or soft soldering or hard soldering can be used. The weld penetration depth should be at least equal to the plate thickness. The inventors have confirmed through actual measurements that there is no decrease in resistance. Copper is the most common material for the coil, but it can also be a conductor such as aluminum. It can also be a combination of dissimilar metals such as copper and aluminum.

[0082] (Coil manufacturing method) Figure 18A , 18B This diagram illustrates the manufacturing method of the segmented coil 3 (first coil). The segmented coil 3 (first coil) is formed, for example, by stamping a sheet metal (see reference). Figure 18A ), bending of flat electromagnetic wire (reference) Figure 18B The manufacturing method is the same for segmented coil 4 (second coil), segmented coil 4_1 (third coil), and other coils.

[0083] For coils, stamping of sheet metal or bending of flat wire can be used. Coils can be non-composite materials or electromagnetic wire with an insulating film.

[0084] (In-wheel motor) Figure 19 This is a perspective view of a wheel 17 including an electric motor (rotary motor) 16 using winding 15 according to this embodiment. In this example, an external rotor type electric motor is assembled inside the wheel 17 as an in-wheel motor 16. However, the electric motor 16 is not limited to an external rotor type and can also be an internal rotor type. A flat coil with a rectangular cross-section is inserted into a slot 1 of the stator core 2 from the direction of rotation and is fixed in the slot 1.

[0085] The coil can be single-layered or multi-layered. Figure 19 In this example, the coil has 6 layers. The coil connections are joined axially using beam welding methods such as electron beam welding (EBW), laser welding, or TIG welding. Soft soldering or hard soldering can also be used.

[0086] As explained above, according to this embodiment, the bonding quality of the coil ends can be improved, and the assembly process can be simplified.

[0087] Furthermore, the present invention is not limited to the embodiments described above, and includes various modifications. For example, the embodiments described above are detailed for ease of understanding and explanation of the present invention, and are not limited to having all the structures described. Additionally, a portion of the structure of one embodiment can be replaced with the structure of another embodiment, and structures of other embodiments can be added to the structure of one embodiment. Furthermore, for a portion of the structure of each embodiment, other structures can be added, deleted, or replaced.

[0088] Alternatively, the present invention can also be implemented in the following ways.

[0089] (2). A stator of a rotary motor having (a) a core with a groove and (b) a plurality of coils with a rectangular cross-section capable of being inserted into the groove, wherein (c) the plurality of coils include an insertion portion 5 capable of being inserted into the groove, (d) a connecting portion 6 electrically connected to the insertion portion 11 of the other coils among the plurality of coils, and (e) an intermediate portion 7 formed between the insertion portion and the connecting portion, (f) the connecting portion having a connecting surface 9 opposite to the other coils in the radial direction of the rotary motor, (g) the intermediate portion having at least one bend 10 when viewed from the rotation axis direction of the rotary motor, and (h) the bend closest to the insertion portion forming a protrusion on the side of the other coils, (i) a stator of a rotary motor.

[0090] (3). In the stator of the rotary motor described in (2), the plurality of coils include a first coil that can be inserted into a first slot and a second coil that can be inserted into a second slot that is circumferentially adjacent to the first slot. The connection between the middle portion of the first coil and the second coil is defined as a first connection portion. The bent portion is formed at a position where the distance between the insertion portion of the first coil and the insertion portion of the second coil is equal or closer to the insertion portion of the first coil than the first connection portion.

[0091] (4). In the stator of the rotary motor described in (2), the plurality of coils include a first coil that can be inserted into a first slot and a second coil that can be inserted into a second slot that is circumferentially adjacent to the first slot. The connection between the middle portion of the first coil and the second coil is defined as a first connection portion. The bending portion includes a first bending portion formed on the side near the insertion portion of the first coil and having a shape that protrudes toward the side of the second coil, and a second bending portion formed on the side near the first connection portion and having a shape that protrudes toward the side opposite to the first bending portion.

[0092] (6). In the stator of the rotary motor described in (4), the first curved portion and the second curved portion are formed such that the distance between the curved portions is greater than the distance between the second curved portion and the first connecting portion.

[0093] Explanation of reference numerals in the attached figures

[0094] 1…slot, 2…stator core, 3…segmented coil, 4…segmented coil, 4_1…segmented coil, 5…insertion part, 6…connection part, 7…intermediate part (first intermediate part), 8…intermediate part (second intermediate part), 9…connection surface, 10…bending part, 11…insertion part, 11_1…insertion part, 12…restoring force, 13…clamping force, 14…stator (electromagnetic component), 15…winding, 16…motor (rotary motor), 17…wheel.

Claims

1. A stator for a rotary electric motor, characterized in that: It includes a core with multiple slots and multiple coils with rectangular cross-sections that can be inserted into each of the slots. Each coil includes an insertion portion that can be inserted into the slot, a connection portion that is electrically connected to other coils, and an intermediate portion formed between the insertion portion and the connection portion. The plurality of coils includes a first coil capable of being inserted into a first slot and a second coil capable of being inserted into a second slot circumferentially adjacent to the first slot. The first coil includes: A first curved portion formed on the side near the insertion portion of the first coil, protruding towards the second coil; and A second curved portion, formed on the side near the insertion portion of the second coil, protrudes in a shape opposite to the first curved portion. The first coil is pressed into close contact with the second coil by the restoring force caused by the residual stress of the first and second bends.

2. The stator of the rotary electric motor as described in claim 1, characterized in that: The first bend and the second bend are formed such that the distance between the first bend and the second bend is greater than the distance between the first bend and the insertion portion of the first coil.

3. The stator of the rotary electric motor as described in claim 1, characterized in that: The first bend and the second bend are formed such that the distance between the first bend and the second bend is greater than the distance between the insertion portion of the second coil and the second bend.

4. The stator of the rotary electric motor as described in claim 1, characterized in that: The plurality of coils includes a third coil. The first curved portion and the second curved portion are positioned differently along the rotation axis of the rotary motor, and the first coil is inserted into the first layer of the first slot. The second coil is inserted into the second slot. The third coil is inserted into the second slot into which the second coil is inserted, and is inserted into the layer adjacent to the second coil in the radial direction of the rotary motor. The connection portion of the first coil and the insertion portion of the third coil are located on the same layer and are positioned on the outside in the direction of rotation axis.

5. The stator of the rotary electric motor as described in claim 1, characterized in that: The end face of the joint where the first coil and the second coil engage is formed in a direction substantially perpendicular to the rotation axis of the rotary motor. The circumferential length of the connecting portion of the first coil is longer than the circumferential length of the insertion portion of the second coil.

6. The stator of the rotary electric motor as described in claim 1, characterized in that: The first curved portion and the second curved portion are configured to be substantially parallel to the axis of rotation.

7. A rotary electric motor, characterized in that: Includes the stator as described in claim 1.

8. A wheel, characterized in that: Including the rotary motor as described in claim 7.

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