Method of manufacturing stator coil

Abstract

To provide a method of manufacturing a stator coil capable of ensuring stable weld quality.SOLUTION: Provided is a method of manufacturing a stator coil which is formed by mutually connecting a plurality of base materials via a filler material by arc welding using a weld electrode provided on a tip end side oof a weld torch. The method of manufacturing the stator coil includes: an arrangement step of arranging the filler material within a region, where one base material overlaps the other base material, between the one base material and the other base material; and a weld step of performing welding by disposing the weld electrode in a direction toward a welding surface of the filler material so as to pass an intersection of the one base material and the other base material.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a method for manufacturing a stator coil. [Background technology]

[0002] Conventionally, when a stator is fabricated by inserting unit coils, each of which is formed by concentrated winding of rectangular wire, into teeth provided on a stator core of a rotating electrical machine, connections are made between the unit coils and between the neutral point and the coils. Such connections are sometimes made by providing a filler material between each base material, such as between the unit coils, and by arc welding, such as TIG welding. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-213423 Summary of the Invention [Problem to be solved by the invention]

[0004] However, during arc welding, the filler metal melts unevenly, sometimes melting one side of the base metal and the other side of the base metal, resulting in so-called melting bias. Therefore, there is room for improvement in terms of ensuring stable welding quality.

[0005] Therefore, an object of the present invention is to provide a method for manufacturing a stator coil that can ensure stable welding quality. [Means for solving the problem]

[0006] In order to solve the above problems, a method for manufacturing a stator coil is a method for manufacturing a stator coil formed by connecting multiple base materials to each other via a filler material by arc welding with a welding electrode provided at the tip side of a welding torch, and includes: a placement process for placing the filler material between one of the base materials and the other of the base materials in a region where the one of the base materials and the other of the base materials overlap; and a welding process for welding by placing the welding electrode in a direction toward the welding surface of the filler material so that it passes through the intersection of the one of the base materials and the other of the base materials. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view schematically illustrating an example of a stator including a stator coil according to a first embodiment; [Figure 2] FIG. 1 is a perspective view schematically showing an example of a connection portion between one unit coil and another unit coil in a stator coil according to a first embodiment; [Figure 3] FIG. 1 is a perspective view showing an example of the appearance of a filler metal in a stator coil according to a first embodiment; [Figure 4] FIG. 10 is a plan view showing an example of a state in which a welding electrode is brought into contact with a filler material in the method for manufacturing a stator coil according to the first embodiment. [Figure 5] FIG. 10 is a side view showing an example of a state in which a welding electrode is brought into contact with a filler material in the method for manufacturing a stator coil according to the first embodiment. [Figure 6] FIG. 10 is a plan view showing an example of a state in which a welding electrode is brought into contact with a filler material in the method for manufacturing a stator coil according to the second embodiment. [Figure 7] FIG. 10 is a plan view showing another example of a state in which the welding electrode is brought into contact with the filler material in the method for manufacturing the stator coil according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Stator coils according to several embodiments will be described below with reference to the drawings. Substantially identical elements in each embodiment are designated by the same reference numerals, and descriptions thereof will be omitted. Furthermore, in the following embodiments, the terms "first" and "second" attached to components are intended to simply distinguish between similar components, and do not indicate superiority or inferiority between the components or a time factor. Furthermore, in each drawing, the dimensions of each component may be enlarged as necessary for ease of explanation, and the dimensional ratios between the components may not necessarily be the same as in reality.

[0009] (First embodiment) First, the first embodiment will be described with reference to FIGS. The stator 10 of the embodiment shown in FIG. 1 constitutes, for example, a part of an inner rotor type rotating electric machine (not shown). A rotor (not shown) is rotatably provided inside the stator 10 with a predetermined gap therebetween relative to the stator 10. The stator 10 is formed, for example, in a substantially cylindrical shape as a whole. In the following description, a direction parallel to the axis of the stator 10 will be referred to as the axial direction. Furthermore, the radial direction of the stator 10 centered on the axis will be simply referred to as the radial direction, and the circumferential direction of the stator 10 centered on the axis will be simply referred to as the circumferential direction.

[0010] The stator 10 has a yoke 11, teeth 12, and a stator coil 20. The yoke 11 and the teeth 12 are formed, for example, by stacking a plurality of flat, annular electromagnetic steel plates. The yoke 11 is formed, for example, in a substantially cylindrical shape as a whole. The teeth 12 are formed extending radially inward from the yoke 11, and are provided in plurality at intervals in the circumferential direction. Slots 13 are provided between adjacent teeth 12 in the circumferential direction. The slots 13 are formed to open radially inward. Note that in FIG. 1, to make the drawing easier to understand, only some of the teeth 12 and slots 13 are labeled with reference numerals, and the reference numerals of the remaining teeth 12 and slots 13 are omitted.

[0011] The stator coil 20 is wound around the teeth 12. The stator coil 20 is electrically connected to a control circuit (not shown) via connection terminals and receives power. The stator coil 20 is formed of a rectangular wire made of a metal material such as a copper alloy or an aluminum alloy. The rectangular wire has a substantially rectangular cross section. The stator coil 20 is made up of a plurality of unit coils 21, each of which has three phases: a U phase, a V phase, and a W phase. The unit coils 21 are assembled and attached so as to be wound around each of the teeth 12. The unit coils 21 are, for example, edgewise coils, and are, for example, about 3 mm thick and about 6 mm wide.

[0012] In this embodiment, the stator coil 20 employs a double star connection, with adjacent unit coils 21 of the same phase being connected to each other by a connection portion 22. Also, unit coils 21 of different phases are connected to each other via a neutral point 23. At the connection portion 22, an end portion 211a of one unit coil 211 and an end portion 212a of the other unit coil 212 are connected to each other.

[0013] The end 211a of one unit coil 211 and the end 212a of the other unit coil 212 are arranged, for example, perpendicular to each other. Of the unit coils 21 of the same phase connected by a connection portion 22, one unit coil 211 corresponds to one base material, and the other unit coil 212 corresponds to the other base material. In the following description, the end 211a of one unit coil 211 may be referred to as a first end 211a, and the end 212a of the other unit coil 212 may be referred to as a second end 212a. In FIG. 1 , to make the drawing easier to understand, only some of the unit coils 21 and connection portions 22 are indicated by reference numerals, and the reference numerals of the other unit coils 21 and connection portions 22 are omitted.

[0014] In the connection portion 22, the first end 211a and the second end 212a are connected to each other via the filler material 31 by arc welding, such as TIG (Tungsten Inert Gas) welding, in which an arc discharge is performed using a welding electrode 91 provided at the tip of a welding torch (not shown). That is, in the connection portion 22, as shown in FIG. 2, the filler material 31 is provided between the first end 211a and the second end 212a. The welding method is not limited to TIG welding, and other methods such as shielded metal arc welding and MIG welding may also be used. As shown in FIG. 3, the filler material 31 is made of, for example, copper and configured in a generally rectangular shape as a whole. The filler material 31 can be configured of the same material as the stator coil 20. The thickness t of the filler material 31 is, for example, 3 mm or less. The width W of the filler material 31 is approximately 2 to 3 mm, and the length L of the filler material 31 is approximately 3 to 4 mm.

[0015] As shown in FIG. 3 , the filler material 31 has an oval cross-sectional shape as viewed in the width direction of the filler material 31. In this case, the filler material 31 is formed by vertically compressing a material cut to a predetermined size from a round bar material having a circular cross-sectional shape. This improves the manufacturability of the filler material 31, thereby suppressing increases in the manufacturing cost of the stator 10. The shape of the filler material 31 is not limited to this, and the cross-sectional shape as viewed in the width direction may be approximately circular or approximately rectangular. When the cross-sectional shape as viewed in the width direction is approximately rectangular, the filler material 31 may be configured with rounded surfaces with chamfered corners. The shape of the filler material 31 is determined mainly for the following purposes (1) to (3): (1) The melting of the filler material 31 ensures welding at the overlapping surfaces with the base materials, such as the unit coils 211 and 212. (2) The heat conduction due to contact with the base materials is utilized to promote welding with the base materials. (3) The remaining molten zone between the base materials suppresses the generation of tensile residual stress in the welded zone.

[0016] Next, an example of a method for connecting one unit coil 211 to the other unit coil 212, i.e., a method for connecting the first end 211a to the second end 212a, will be described with reference to Figures 4 and 5. In connecting the first end 211a to the second end 212a, for example, an arrangement step and a welding step are performed in this order. The arrangement step and the welding step are performed on multiple connection portions 22, thereby manufacturing the stator coil 20. The arrangement step includes a step of placing a filler material 31 in a region S between one unit coil 211 and the other unit coil 212, where the first end 211a and the second end 212a overlap. In Figure 4 and other figures, the range of the region S is indicated by hatching.

[0017] As shown in FIG. 4, the positioning step includes positioning the welding surface 311 of the filler material 31 facing the welding electrode 91 so that it is oriented at a predetermined angle θ1 with respect to the extending direction of the first end 211a and the second end 212a. The predetermined angle θ1 is set to any angle between 40 and 50 degrees, preferably 45 degrees. The welding surface 311 is formed by the outer side surface of the filler material 31 in the longitudinal direction. In this case, the intersection of the first end 211a and the second end 212a is located within the extending region of the welding surface 311. The filler material 31 is temporarily fixed by the elastic force acting between the first end 211a and the second end 212a.

[0018] The welding process includes a step of welding by positioning the welding electrode 91 toward the welding surface 311 of the filler material 31 so that the electrode passes through the intersection of the first end 211a and the second end 212a, as indicated by the black arrow in FIG. 5 . Then, with the tip of the welding electrode 91 positioned a predetermined distance, e.g., 1.5 mm, from the welding surface 311, an arc discharge is generated by passing current through the electrode 91, and the filler material 31 is welded to each end 211a, 212a. In this case, by passing the welding electrode 91 through the intersection of the first end 211a and the second end 212a, the welding electrode 91 is positioned at the shortest distance from the welding surface 311. Furthermore, during welding, the welding electrode 91 is positioned perpendicular to the welding surface 311. This positions the filler material 31 within the range of the arc discharge generated by the welding electrode 91, allowing the filler material 31 to be uniformly melted. In this way, the first end 211a and the second end 212a can be stably welded together via the filler material 31, thereby ensuring sufficient welding strength. The above-described method of connecting the first end 211a and the second end 212a can also be applied to connecting the unit coil 21 to the neutral point 23, etc.

[0019] According to the embodiment described above, the method for manufacturing the stator coil 20 is a method for manufacturing the stator coil 20 by connecting one unit coil 211 and the other unit coil 212 to each other via the filler material 31 by arc welding with the welding electrode 91 provided at the tip side of a welding torch. The method for manufacturing the stator coil 20 includes an arrangement step and a welding step. The arrangement step includes a step of arranging the filler material between the one unit coil 211 and the other unit coil 212 in a region S where the one unit coil 211 and the other unit coil 212 overlap. The welding step includes a step of welding by placing the welding electrode 91 in a direction toward the welding surface 311 of the filler material 31 so as to pass through an intersection between the one unit coil 211 and the other unit coil 212.

[0020] This allows the filler material 31 to be melted uniformly during arc welding, thereby preventing uneven melting and ensuring stable welding quality, thereby improving the quality of the stator coil 20.

[0021] The first end 211a and the second end 212a are disposed perpendicular to each other. The disposing step includes a step of disposing the welding surface 311 of the filler material 31 facing the welding electrode 91 so that the welding surface 311 faces an angle ranging from 40 degrees to 50 degrees with respect to the extending direction of the first end 211a and the second end 212a.

[0022] This allows the arc discharge from the welding electrode 91 to be brought into uniform contact with the filler material 31, so that arc heat can be effectively input to the first end 211a and the second end 212a. This ensures a stable molten state, further improving the welding quality.

[0023] The filler metal 31 has an oval cross section when viewed from the width direction. This allows the contact area of the filler metal 31 with the first end 211a and the second end 212a to be stably secured. This allows arc heat to be effectively input to the first end 211a and the second end 212a during welding, ensuring stable welding quality.

[0024] The unit coils 211, 212 are set to a thickness of 3 mm and a width of 6 mm. The thickness of the filler material 31 is 3 mm or less. This makes it easier for the filler material 31 to melt uniformly at the first end 211a and the second end 212a. This prevents uneven melting of the filler material 31 and ensures stable welding quality.

[0025] (Second embodiment) Next, a second embodiment will be described with reference to FIGS. 6 and 7. The second embodiment differs from the first embodiment in the content of the arrangement step. Specifically, in the first embodiment, the arrangement step involves arranging the welding surface 311 of the filler material 31 facing the welding electrode 91 so that it faces a predetermined angle θ1 with respect to the extending direction of the first end 211a and the second end 212a. In contrast, in the second embodiment, the arrangement step includes a step of arranging the welding surface 311 of the filler material 31 facing the welding electrode 91 so that it faces parallel to the extending direction of the first end 211a or the extending direction of the second end 212a.

[0026] Specifically, the filler material 31 is arranged so that the welding surface 311 faces parallel to the direction in which the second end 212a extends. In this case, during the welding process, the welding electrode 91 is arranged in a direction from the second end 212a toward the inside of the region S. During the welding process, the welding electrode 91 faces the welding surface 311 at an angle θ2. The angle θ2 is set in the range of 55 degrees to 65 degrees, and preferably 62 degrees. This second embodiment also achieves the same effects as the first embodiment.

[0027] Furthermore, since the arc discharge from the welding electrode 91 can be brought into uniform contact with the filler material 31, arc heat can be effectively input to the first end 211a and the second end 212a. This ensures a stable molten state, further improving the welding quality.

[0028] 7, the filler metal 31 may be arranged so that the welding surface 311 faces parallel to the direction in which the first end portion 211a extends. In the example of FIG. 7, in the welding process, the welding electrode 91 is arranged in a direction from the first end portion 211a side toward the inside of the region S.

[0029] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as defined in the claims. [Explanation of symbols]

[0030] In the drawing, 20 indicates a stator coil, 211 indicates one unit coil (one base material), 211a indicates a first end (end of one base material), 212 indicates the other unit coil (the other base material), 212a indicates a second end (end of the other base material), and 91 indicates a welding electrode.

Claims

1. A method for manufacturing a stator coil formed by connecting a plurality of base materials to each other via a filler material by arc welding using a welding electrode provided at the tip side of a welding torch, a disposing step of disposing the filler metal between one of the base materials and the other of the base materials in a region where the one of the base materials and the other of the base materials overlap; a welding process in which the welding electrode is positioned in a direction toward the welding surface of the filler metal so as to pass through an intersection between one of the base metals and the other of the base metals, A method for manufacturing a stator coil.

2. an end portion of one of the base materials and an end portion of the other of the base materials are disposed perpendicular to each other; The positioning step includes a step of positioning the filler metal so that the welding surface of the filler metal facing the welding electrode is oriented at an angle ranging from 40 degrees to 50 degrees with respect to an extending direction of an end portion of one of the base metals and an end portion of the other of the base metals. The method for manufacturing a stator coil according to claim 1 .

3. The positioning step includes a step of positioning the filler metal so that the welding surface of the filler metal facing the welding electrode is oriented parallel to an extension direction of an end portion of one of the base metals or an extension direction of an end portion of the other base metal. The method for manufacturing a stator coil according to claim 1 .

4. The filler material has an oval cross-sectional shape when viewed from the width direction. The method for manufacturing a stator coil according to claim 1 .

5. The base material has a thickness of 3 mm and a width of 6 mm, The thickness of the filler metal is 3 mm or less. The method for manufacturing a stator coil according to claim 4 .

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