Method for manufacturing stator of rotating electric machine, stator of rotating electric machine, and rotating electric machine

Abstract

The present invention improves the reliability of a rotating electric machine. The present invention is a method for manufacturing a stator, the stator being used in a rotating electric machine, the method comprising: a first step of arranging a first segment coil and a second segment coil relative to each other; a second step of processing the first segment coil in such a way as to generate a bridge portion contacting the second segment coil; and a third step of joining the bridge portion and the second segment coil by laser welding.

Description

Technical Field

[0001] The present invention relates to a stator of a rotating electrical machine and a method for manufacturing the same. Background Art

[0002] Rotating electric machines generate a rotating magnetic field by supplying alternating current to the stator coils, which in turn rotates the rotor. Furthermore, mechanical energy applied to the rotor can be converted into electrical energy, outputting alternating current from the coils. In this way, rotating electric machines operate as motors or generators. The increasing number of turns of the flat wire in the stator of rotating electric machines, and the resulting increase in the number of weld points, has traditionally posed a productivity challenge in TIG welding.

[0003] Therefore, the industry is looking into using laser welding to manufacture stators.

[0004] The following prior art serves as background technology in this technical field. Patent Document 1 (Japanese Patent Application Laid-Open No. 2013-109948) describes a structure for joining flat wires, namely, a joined body, in which the ends of flat wires with a rectangular cross-section and coated with an insulating film are welded together. The structure is achieved by irradiating the end faces of the flat wires with a laser spot from above to heat the flat wires, while the ends are joined together with the insulating film peeled off from only one side of the ends facing each other.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-109948 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] When laser welding is used in stator manufacturing, the laser irradiates the insulation (eg, enamel) covering the winding surface, burning the insulation and exposing the copper. This degrades the insulation of the coil and reduces the reliability of the rotating electrical machine.

[0010] Technical means to solve the problem

[0011] A representative example of the invention disclosed in this application is shown below. Specifically, a method for manufacturing a stator for use in a rotating electrical machine is characterized by comprising: a first step of arranging a first segment coil and a second segment coil facing each other; a second step of processing the first segment coil to form a bridge portion that contacts the second segment coil; and a third step of joining the bridge portion and the second segment coil by laser welding.

[0012] Effects of the Invention

[0013] According to the present invention, welding is performed while leaving the enamel coating on the non-joined surfaces, thereby ensuring insulation and improving the reliability of the rotating electrical machine. Other issues, configurations, and effects will become clearer through the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram showing the overall structure of a rotating electrical machine according to an embodiment of the present invention.

[0015] Figure 2 It is a perspective view showing a stator of a rotating electrical machine according to an embodiment of the present invention.

[0016] Figure 3 A three-dimensional diagram of the stator core.

[0017] Figure 4 This is a three-dimensional view of the coil end after welding.

[0018] Figure 5A This figure shows a flat wire before being processed into segment coils.

[0019] Figure 5B This figure shows the flat line after the enamel coating is removed.

[0020] Figure 5C This is a diagram showing the flat wire after cutting.

[0021] Figure 5D FIG. 1 is a diagram showing the segment coil after shaping.

[0022] Figure 6A A perspective view of the segment coils arranged in the armature slots.

[0023] Figure 6B This is a perspective view of the segment coil after the bridge portion is formed.

[0024] Figure 6C A diagram showing the formation of a bridge portion.

[0025] Figure 6D A diagram showing the welding of segment coils.

[0026] Figure 6E This is a three-dimensional view of the segment coil after welding.

[0027] Figure 7 A three-dimensional view of the coil end after TIG welding. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0029] The rotating electric machine of this embodiment is suitable for use in automobiles. Electric vehicles that use rotating electric machines include hybrid electric vehicles (HEVs) equipped with both an engine and a rotating electric machine, and pure electric vehicles (EVs) that rely solely on the rotating electric machine for propulsion without an engine. The rotating electric machine described below can be used in both types of vehicles.

[0030] Figure 1 Schematic diagram showing the overall structure of a rotating electrical machine 100 according to an embodiment of the present invention. Figure 1 , a portion of the rotating electrical machine 100 is shown in cross section to illustrate the interior of the rotating electrical machine 100. The rotating electrical machine 100 is disposed within a housing 10 and includes a case 112, a stator 130, and a rotor 150. The stator 130 is fixed to the housing 112 and includes a stator core 132. The rotor 150 is rotatably disposed within the stator 130. The housing 10 can be integrally formed with an engine housing or a transmission housing.

[0031] The rotating electrical machine 100 is a three-phase synchronous motor with an internal permanent magnet. In this embodiment, a three-phase synchronous motor is described as an example of the rotating electrical machine 100, but the present invention can also be applied to an induction motor.

[0032] Rotating electric machine 100 of this embodiment operates as an electric motor, rotating rotor 150 by supplying three-phase AC current to stator coils 138 wound around stator core 132. Furthermore, when driven by the engine, rotating electric machine 100 operates as a generator, outputting the generated three-phase AC power. In other words, rotating electric machine 100 functions both as an electric motor, generating rotational torque from electrical energy, and as a generator, generating electricity from mechanical energy. These functions can be selectively utilized depending on the vehicle's driving conditions.

[0033] Stator 130 is fixed in housing 112. Flange 115 provided on housing 112 is fastened to casing 10 by bolts 12, thereby securing and retaining stator 130 within casing 10. Rotor 150, fixed to shaft 118, is supported by bearings 14A and 14B of casing 10 and rotatably retained within stator core 132.

[0034] Figure 2 1 is a perspective view showing the stator 130 installed in the housing 112. Figure 3 The stator core 132 is a three-dimensional view. The housing 112 is formed into a cylindrical shape by drawing a steel plate (high-tensile steel plate, etc.) with a thickness of about 2 to 5 mm. A flange 115 is provided at one axial end of the housing 112 and is fixed to the housing 10 by bolts as described above (see FIG. Figure 1The flange 115 is formed integrally with the housing 112 by drawing. Alternatively, the stator 130 may be directly fixed to the casing 10 without providing the housing 112.

[0035] Stator 130 is fixed to the inner circumference of housing 112 and comprises a cylindrical stator core 132 and stator coils 138 mounted on stator core 132. Stator core 132 is formed by laminating multiple electromagnetic steel sheets 133, for example, with a thickness of approximately 0.05 to 1.0 mm, formed by punching or etching. The stacked electromagnetic steel sheets 133 are connected and secured by welding to prevent deformation of the electromagnetic steel sheets 133 caused by the clamping force when pressed into housing 112.

[0036] A plurality of armature slots 420 extending in the axial direction are formed on the stator core 132 at equal intervals in the circumferential direction. The number of the armature slots 420 is, for example, 72 in this embodiment. Figure 2 As shown, the stator coil 138 is housed in the armature slot 420. Figure 3 In the example shown, the armature slots 420 are open armature slots, having openings formed on the inner circumference of the stator core 132. The circumferential width of the openings is preferably approximately equal to or slightly smaller than the coil mounting portions of the armature slots 420 in which the stator coils 138 are mounted.

[0037] Furthermore, insulating paper (so-called slot liner) 300 is disposed within each armature slot 420. The insulating paper 300 is, for example, a heat-resistant polyamide paper insulating sheet having a thickness of approximately 0.1 to 0.5 mm. The insulating paper 300 is disposed between the armature slots 420 and the coil ends 140a and 140b. By disposing the insulating paper 300 within the armature slots 420, the insulation between the coils inserted into the armature slots 420 and between the coils and the inner surfaces of the armature slots 420 is improved.

[0038] The stator coil 138 is a plurality of U-shaped segment coils 28 (see Figure 4 、 Figure 5D ) are connected to each other. The segment coils 28 are arranged so that their ends protrude from the armature slots 420 (i.e., the stator 130) with one end adjacent to another segment coil 28 and the other end adjacent to yet another segment coil 28. The adjacent ends of the segment coils 28 with adjacent ends are connected to each other, thereby forming the stator coil 138 wound around the stator core 132.

[0039] Furthermore, the insulating paper 300 provided at the coil ends 140a and 140b is annularly arranged between the coils to provide phase insulation and conductor insulation at the coil ends 140a and 140b. Thus, in the rotating electric machine 100 of this embodiment, the insulating paper 300 is provided inside the armature slots 420 and at the coil ends 140a and 140b. This ensures that the required dielectric strength is maintained even if the enamel coating 281 used for coil insulation is damaged or degraded.

[0040] Pinions 430 are formed between the armature slots 420. Each pinion 430 is integrally formed with an annular core back 440. The stator core 132 is a one-piece core in which each pinion 430 is integrally formed with the core back 440. The pinions 430 guide the rotating magnetic field generated by the stator coil 138 to the rotor 150, causing the rotor 150 to generate rotational torque.

[0041] The rotor 150 includes a rotor core 152 and permanent magnets 154 held in magnet insertion holes formed in the rotor core 152 .

[0042] The rotor core 152 has rectangular magnet insertion holes formed near the outer periphery at equal intervals along the circumferential direction. Permanent magnets 154 are embedded in each magnet insertion hole and secured with adhesive or the like. The circumferential width of the magnet insertion holes is larger than the circumferential width of the permanent magnets 154, thereby forming magnetic gaps 156 on either side of the permanent magnets 154. These magnetic gaps 156 can be embedded with adhesive or solidified with the permanent magnets 154 using resin.

[0043] Permanent magnets 154 form the field magnetic poles of rotor 150. While one permanent magnet 154 forms one magnetic pole in this embodiment, multiple permanent magnets may also form one magnetic pole. By increasing the number of permanent magnets used to form each magnetic pole, the magnetic flux density of each magnetic pole emitted by the permanent magnets increases, thereby increasing the magnet torque. Permanent magnets 154 can be made of neodymium or samarium sintered magnets, ferrite magnets, or neodymium bonded magnets. The ideal residual magnetic flux density of permanent magnets 154 is approximately 0.4 to 1.3 T, with neodymium magnets being particularly suitable. Auxiliary magnetic poles may also be formed between each permanent magnet 154.

[0044] When a rotating magnetic field is generated in stator 130 by supplying three-phase AC current to stator coil 138, this rotating magnetic field acts on permanent magnets 154 of rotor 150, generating magnet torque. In addition to this magnet torque, the aforementioned reluctance torque is also generated in rotor 150. Therefore, both the magnet torque and the reluctance torque act on rotor 150 as rotational torque, enabling a high rotational torque to be obtained.

[0045] Figure 4This is a perspective view of the coil end portion 140b after welding.

[0046] In this embodiment, eight segment coils 28 are arranged in each armature slot 420. Figure 4 As shown, the ends of two adjacent segment coils 28 are connected by welding to form coil end portions 140b. For example, the ends of the segment coils 28 are connected by melting the base material of the copper wire constituting the segment coils 28 using arc welding such as laser welding or TIG (Tungsten Inert Gas) welding, or plasma welding to form welded portions 30.

[0047] 5A to 5D This is a diagram showing the processing of the segment coil 28.

[0048] The segment coil 28 is Figure 5A The long flat wire shown in the figure is processed.

[0049] Then, the flat wire is thinned by removing the enamel coating 281 at the end of the segment coil 28 (see FIG. Figure 5B The enamel coating 281 can be removed by laser or surface cutting. When the segment coil 28 is processed, the enamel removal portion 282 is set on a different surface of the flat wire (refer to Figure 5D ), so the enamel coating 281 is removed on different sides of the flat wire (reference Figure 5C ).

[0050] Thereafter, the flat wire is cut to a predetermined length at the position of the enamel removal portion 282. The segment coil 28 cut to the desired length has enamel removal portions 282 at both ends, and the enamel removal portions 282 are provided on the opposite side surfaces (see FIG. Figure 5C ).

[0051] Afterwards, if Figure 5D As shown, the flat wire is shaped into a U-shaped segment coil 28 and inserted into the armature slot 420 of the stator core 132 .

[0052] Figures 6A to 6E It is a figure which shows the welding process of the end part of the segment coil 28.

[0053] like Figure 6A As shown, the segment coils 28 inserted into the armature slots 420 of the stator core 132 are arranged with their enamel-removed portions 282 facing each other (first step). In this state, the enamel-removed portions 282 are formed on the facing surfaces of the segment coils 28, while the enamel coating 281 remains on the surfaces other than the facing surfaces. The removal of the enamel coating (or the copper base material together with the enamel coating 281) creates a gap 29 between the facing segment coils 28.

[0054] Then, along the specified direction ( Figure 6B The end faces of the segment coils 28 are cut (from right to left in the figure) to form bridges 283 in the gaps 29 between the segment coils 28 (the second step). The bridges 283 are formed so as to extend until they contact the segment coils 28 facing their ends. It is preferable to form an R-shaped portion with a radius of approximately 0.5 mm on the side of the segment coils 28 opposite the bridge 283 where the bridges 283 are formed.

[0055] Regarding the processing of the bridge portion 283, for example, Figure 6C As shown, the tip of the segment coil 28 is clamped between the lower and upper blades. The upper blade is then moved in the direction of the arrow to cut the end of the segment coil 28. This forms a bridge 283 and rounded edge 284 at the end of the segment coil 28 on the upper blade side. The gap between the upper and lower blades is preferably 0.04 to 0.08 mm.

[0056] Furthermore, it is preferable to provide a slight chamfer (e.g., approximately 0.5 mm) or curved surface at the tip of the upper blade to form the bridge portion 283 of an appropriately sized portion. Furthermore, the bridge portion 283 and the rounded portion 284 can also be formed using a mold (e.g., a die). In this case, the bridge portion 283 and the rounded portion 284 are preferably formed before the segment coil 28 is inserted into the armature slot 420. For example, the bridge portion 283 and the rounded portion 284 can be formed when the flat wire is cut or processed into a U-shape.

[0057] like Figure 6B As shown, the bridge portion 283 may be formed in one segment coil 28 or in two segment coils 28. In this case, the segment coils 28 are arranged so that the bridge portions 283 face each other.

[0058] After forming the bridge portion 283, as shown in FIG. Figure 6D As shown, laser light is irradiated onto bridge portion 283 to melt the copper and form welded portion 30 (third step). Bridge portion 283 blocks the gap 29 between segment coils 28 from being visible from above. Bridge portion 283 shields the laser light irradiated from above, preventing the laser light from entering gaps 29 between segment coils 28 and impinging on enamel coating 281, thereby reducing damage to enamel coating 281 during welding.

[0059] Then, if Figure 6E As shown, the molten copper enters the gap 29 to form a weld 30. The molten copper flows into the gap 29 between the segment coils 28 to electrically and mechanically connect the segment coils 28 to each other.

[0060] In the above description, the segment coils 28 are connected by laser welding, but it can also be connected by Figure 7 As shown, the segment coils 28 are connected by TIG welding.

[0061] As described above, according to the embodiment of the present invention, the first step of arranging the first segment coil 28 and the second segment coil 28 facing each other is included; the second step of processing the first segment coil 28 to form a bridge portion 283 that contacts the second segment coil 28; and the third step of joining the bridge portion 283 and the second segment coil 28 by laser welding. Consequently, the enamel coating 281 of the segment coil 28 is removed from the surface facing the other segment coil 28 in the weld portion 30, leaving the enamel coating 281 on the other surfaces. This allows connection with the enamel coating 281 remaining on the surfaces other than the connection surface, improving insulation. Furthermore, since the enamel coating 281 is more easily adhered to by powder coating than copper, the enamel coating 281 and the powder coating enhance insulation. Furthermore, laser welding prevents bulging of the weld portion 30, reducing the height of the coil ends.

[0062] Furthermore, in the third step, since the segment coils 28 are joined together by irradiating the bridge portion 283 with laser light, damage to the enamel coating 281 can be reduced and only copper required for joining can be melted.

[0063] In addition, the segment coil 28 has a covered portion covered by an insulating film and an exposed portion not covered by the insulating film. The segment coil 28 is arranged relative to each other with a gap 29 between the exposed portions, so the portion other than the joint surface is covered by the enamel coating 281, thereby reducing the distance between the segment coil 28 and the shell 112.

[0064] Furthermore, the above description is merely an example, and the interpretation of the invention is neither limited nor constrained by the correspondence between the matters described in the above embodiments and the matters described in the claims. For example, the above embodiments illustrate a rotating electrical machine with permanent magnets in its rotor, but the present invention is equally applicable to the stators of rotating electrical machines such as induction motors. Furthermore, the present invention can be applied to other rotating electrical machines besides those used to drive vehicles. Furthermore, a portion of the components of one embodiment may be replaced with components of another embodiment, and components of another embodiment may be added to components of one embodiment.

[0065] Furthermore, the present invention encompasses various variations and equivalent configurations within the spirit of the appended claims and is not limited to the aforementioned embodiments. For example, the aforementioned embodiments are provided for the purpose of providing a detailed description of the present invention in an easily understandable manner, and the present invention is not necessarily limited to all of the configurations described. Furthermore, portions of the configurations of one embodiment may be replaced with configurations of another embodiment. Furthermore, configurations of another embodiment may be added to the configurations of one embodiment.

[0066] Furthermore, part of the configuration of each embodiment may be added, deleted, or replaced with another configuration.

[0067] Explanation of symbols

[0068] 28…Segment coil

[0069] 29…Gap

[0070] 30…Welding section

[0071] 100...Rotating motor

[0072] 130…stator

[0073] 132… stator core

[0074] 140a, 140b...coil ends

[0075] 150…Rotor

[0076] 281…Enamel coating

[0077] 282…Enamel removal

[0078] 283…Hashibe

[0079] 284…R

[0080] 300...Insulation paper

[0081] 420…Armature slot.

Claims

1. A method for manufacturing a stator, wherein the stator is used in a rotating electrical machine, the method comprising: The first step is to arrange the first section coil and the second section coil relative to each other; a second step of processing the first segment coil so as to generate a bridge portion in contact with the second segment coil; and In a third step, the bridge portion and the second segment coil are joined by laser welding. The first segment coil and the second segment coil each have an exposed portion not covered by an insulating film and a covered portion covered by an insulating film formed on a surface opposite to the exposed portion. The first segment coil and the second segment coil are arranged to face each other with a gap therebetween at a location where the exposed portion faces each other.

2. The method for manufacturing a stator according to claim 1, characterized in that: In the third step, the bridge portion is irradiated with laser light to join the first segment coil and the second segment coil.

3. A method for manufacturing a stator, wherein the stator is used in a rotating electrical machine, the method for manufacturing the stator comprising: The first step is to process the first segment coil in such a manner as to produce a bridge portion in contact with the second segment coil; a second step of arranging the first segment coil and the second segment coil to be opposite to each other; and In a third step, the bridge portion and the second segment coil are joined by laser welding. The first segment coil and the second segment coil each have an exposed portion not covered by an insulating film and a covered portion covered by an insulating film formed on a surface opposite to the exposed portion. The first segment coil and the second segment coil are arranged to face each other with a gap therebetween at a location where the exposed portion faces each other.

4. The method for manufacturing a stator according to claim 3, characterized in that: In the third step, the bridge portion is irradiated with laser light to join the first segment coil and the second segment coil.

5. A stator of a rotating electrical machine, comprising: a core portion having armature slots formed therein; and The segment coil is arranged in the armature slot and covered by an insulating film. The stator is characterized in that The segment coil has a bridge portion protruding from one or both ends of the pair of segment coils and contacting the other segment coil. The pair of segment coils are joined by welding the bridge portion, and a welded portion is formed at the position of the bridge portion. Each of the segment coils has an exposed portion not covered by an insulating film and a covered portion formed on a surface opposite to the exposed portion and covered by the insulating film. The welding portion is formed in the exposed portion so as to fill the gap between the segment coils.

6. The stator according to claim 5, characterized in that: A corner portion of an end portion of the segment coil having the bridge portion, which is opposite to the welding portion, is formed as a curved surface.

7. The stator according to claim 5, characterized in that: The pair of segment coils are joined together by irradiating the bridge portion with laser light.

8. A rotating electrical machine, characterized in that: A stator according to any one of claims 5 to 7 is provided.

Images