Stator manufacturing method

Abstract

The present invention uniformly welds two coil ends to a busbar with one weld.　Provided is a stator manufacturing method in which two coil ends (181) that lead out from a coil (18) wrapped around teeth of a stator core are welded to a coil joining part (22U2) of a busbar (22U), so as to manufacture a stator. In this manufacturing method, when the two coil ends (181) are welded to the coil joining part (22U2) by generating an arc between one of the coil ends (181) and an electrode of an arc welding machine in a state where the two coil ends (181) which each extend in a first direction and are adjacent to each other in a second direction are placed in contact in a third direction with an end face of the coil joining part (22U2), the combined volume of the two coil ends (181) and the coil joining part (22U2) is set to be greater on one coil end (181) side than on the other coil end (181) side.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a stator.

Background Art

[0002] Japanese Patent No. 5153167 discloses a winding connection device for a rotating machine including a connection member (bus bar) that is connected externally to a stator winding (coil) wound around a stator core of the stator. In this device, the connection member is provided with a winding connection terminal for accommodating an end portion of the stator winding. The winding connection terminal is provided with a U-shaped groove capable of accommodating the stator winding between a main body portion and two corner portions extending from the main body portion. One end (coil terminal) of the stator winding is accommodated in this U-shaped groove, and the two corner portions are melted and welded by TIG welding. When the total area of the two corner portions is T and the cross-sectional area of the stator winding is S, the winding connection terminal is formed so as to satisfy 1 ≤ (T / S) ≤ 3. Thereby, the winding connection terminal is made into an optimal welding shape.

Summary of the Invention

Problems to be Solved by the Invention

[0003] In the above prior art, although one coil terminal is welded to the bus bar, there are cases where two coil terminals are welded to the bus bar. In that case, for example, while the two coil terminals are brought into contact with the bus bar by a jig, arc welding is performed aiming at one coil terminal. Thus, when aiming at one coil terminal, the side of the one coil terminal is preferentially melted, and there may be a case where the other coil terminal has insufficient welding.

[0004] In consideration of the above facts, an object of the present invention is to obtain a method for manufacturing a stator capable of evenly welding two coil terminals to a bus bar by a single welding.

Means for Solving the Problems

[0005] A first aspect of the present invention is a method for manufacturing a stator, which involves welding two coil ends leading out from a coil wound around the teeth of a stator core to a coil joint of a busbar, wherein the two coil ends, each extending in a first direction and adjacent to each other in a second direction perpendicular to the first direction, are in contact with the end face of the coil joint in a third direction perpendicular to both the first and second directions, and an arc is generated between one of the coil ends and the electrode of an arc welding machine to weld the two coil ends to the coil joint, wherein the combined volume of the two coil ends and the coil joint is set to be larger on the side of one coil end than on the side of the other coil end.

[0006] In the first embodiment, the volume of the two coil ends is the volume of the portion of the two coil ends that overlaps with the coil joint when viewed from the third direction, and the volume of the portion of the two coil ends that is closer to the tip than those portions.

[0007] In the first embodiment of the stator manufacturing method, the stator is manufactured by welding two coil ends, which are derived from a coil wound around the teeth of the stator core, to the coil joint of a busbar. In this manufacturing method, two coil ends, each extending in a first direction and adjacent to each other in a second direction perpendicular to the first direction, are in contact with the end face of the coil joint in a third direction perpendicular to both the first and second directions. In this state, an arc is generated between one coil end and the electrode of an arc welding machine, and the two coil ends are welded to the coil joint. In other words, arc welding is performed targeting one of the coil ends. During this welding, the combined volume of the two coil ends and the coil joint is set to be larger on the side of one coil end than on the side of the other coil end. This makes it possible to equalize the heat capacity, including the coil joint, on both the side of one coil end and the side of the other coil end when arc welding is performed targeting one of the coil ends. As a result, the two coil ends and the coil joint can be melted evenly on both sides, making it possible to weld both coil ends evenly to the busbar in a single welding operation.

[0008] A second embodiment of the present invention is a method for manufacturing a stator in which, in the first embodiment, the coil joint is formed in an asymmetric shape in the second direction.

[0009] In the second embodiment of the stator manufacturing method, the coil joint of the busbar is formed in an asymmetric shape in the second direction. This makes it possible to set the volume of the coil joint to be larger on one coil end side than on the other coil end side.

[0010] A third aspect of the present invention relates to a method for manufacturing a stator, in which, in the second aspect, an overhang is provided at the coil joint that contacts one coil terminal from the opposite side of the other coil terminal.

[0011] In the third embodiment of the stator manufacturing method, a protruding portion is provided at the coil joint that contacts one coil end from the opposite side of the other coil end. This makes it possible to form the coil joint of the busbar in an asymmetric shape in the second direction, and to set the volume of the coil joint to be larger on the side of one coil end than on the side of the other coil end.

[0012] A fourth aspect of the present invention is a method for manufacturing a stator, in which two coil ends leading out from a coil wound around the teeth of a stator core are welded to a coil joint of a busbar, wherein the two coil ends, each extending in a first direction and adjacent to each other in a second direction perpendicular to the first direction, are brought into contact with the end face of the coil joint using a jig in a third direction perpendicular to both the first and second directions, and an arc is generated between one of the coil ends and the electrode of an arc welding machine to weld the two coil ends to the coil joint, wherein the combined volume of the two coil ends, the coil joint, and the jig is set to be larger on the side of one coil end than on the side of the other coil end.

[0013] In a fourth embodiment of the stator manufacturing method, the stator is manufactured by welding two coil ends derived from a coil wound around the teeth of the stator core to the coil joint of a busbar. In this manufacturing method, two coil ends, each extending in a first direction and adjacent to each other in a second direction perpendicular to the first direction, are welded to the end face of the coil joint in the first and second directions. The coils are brought into contact with a jig in a third, orthogonal direction. In this state, an arc is generated between one coil end and the electrode of the arc welding machine, and the two coil ends are welded to the coil joint. In other words, arc welding is performed targeting one coil end. During this welding, the combined volume of the two coil ends, the coil joint, and the jig is set to be larger on the side of one coil end than on the side of the other coil end. This makes it possible to equalize the heat capacity, including the coil joint and the jig, on both the side of one coil end and the other coil end when arc welding is performed targeting one coil end. As a result, the two coil ends and the coil joint can be melted evenly on both sides, making it possible to weld both coil ends evenly to the busbar in a single welding pass. [Effects of the Invention]

[0014] As described above, the stator manufacturing method according to the present invention makes it possible to evenly weld two coil ends to the busbar in a single welding operation. [Brief explanation of the drawing]

[0015] [Figure 1] This is a perspective view showing the stator in the manufacturing process according to the embodiment. [Figure 2] This is a plan view showing the stator in the manufacturing process according to the embodiment. [Figure 3] This is a perspective view showing a magnified portion of Figure 1. [Figure 4] This is a plan view showing an enlarged portion of Figure 2. [Figure 5] This is a perspective view showing a part of the busbar unit included in the stator according to the embodiment. [Figure 6] It is a plan view showing a coil joint of a bus bar and two coil terminals. [Figure 7] It is a schematic diagram showing an arc welding machine used for welding the coil joint and the two coil terminals. [Figure 8] It is a plan view showing a state where the coil joint and the two coil terminals are welded. [Figure 9] It is a side view showing a state where the coil joint and the two coil terminals are welded. [Figure 10] It is a plan view showing a coil joint of a bus bar according to a comparative example and two coil terminals. [Figure 11] It is a plan view showing a state where the coil joint of the bus bar according to the comparative example and the two coil terminals are welded. [Figure 12] It is a plan view showing a coil joint of a bus bar included in a stator according to a first modification example and two coil terminals. [Figure 13] It is a side view showing a state of viewing the two coil terminals shown in FIG. 12 from the side. [Figure 14] It is a plan view showing a coil joint of a bus bar included in a stator according to a second modification example and two coil terminals. [Figure 15] It is a side view showing a state of viewing the two coil terminals shown in FIG. 14 from the side. [Figure 16] It is a plan view showing a coil joint of a bus bar included in a stator according to a third modification example and two coil terminals. [Figure 17] It is a side view showing the configuration shown in FIG. 16 as viewed from the right side of FIG. 16. [Figure 18] It is a plan view showing a coil joint of a bus bar included in a stator according to a fourth modification example and two coil terminals. [Figure 19] It is a side view showing the configuration shown in FIG. 18 as viewed from the right side of FIG. 18. [Figure 20] It is a plan view showing a coil joint of a bus bar included in a stator according to a fifth modification example and two coil terminals. [Figure 21]This is a plan view showing the coil joint of the busbar, the two coil terminals, and the jig of the stator according to the sixth modified example. [Modes for carrying out the invention]

[0016] The method for manufacturing a stator according to an embodiment of the present invention will be described below with reference to Figures 1 to 20. Note that the scale of the drawings has been appropriately adjusted in each figure. Also, some reference numerals have been omitted in each figure for the sake of clarity.

[0017] Figures 1 and 2 show the stator 10 in the process of being manufactured by the stator manufacturing method according to this embodiment. First, the configuration of the stator 10 will be described. This stator 10 is an armature (stator) comprising a stator core 12, a plurality of coils 18 (24 in this case), and a busbar unit 20. The stator core 12, the plurality of coils 18, and the busbar unit 20 are housed in a cylindrical case 28. A rotor (not shown) is arranged inside this stator 10, forming an inner rotor type motor (rotating electric machine). This motor is a three-phase motor as an example.

[0018] The stator core 12 is constructed by laminating multiple iron core pieces made of electrical steel sheets. This stator core 12 is formed in an annular shape and has a yoke 14 and multiple (in this case, 24) teeth 16. The yoke 14 is cylindrical. The multiple teeth 16 are formed to protrude radially inward from the inner circumferential surface of the yoke 14. The multiple teeth 16 are formed at equal intervals in the circumferential direction of the stator core 12, and slots (not shown) are formed between each of the multiple teeth 16. This stator 10 is fitted inside the case 28. Note that the number of poles and slots of the stator 10 shown in Figures 1 and 2 are merely examples and are not limited thereto.

[0019] Multiple coils 18 are each spirally wound around multiple teeth 16. An insulator, such as an insulator, insulating paper, or varnish, is interposed between each coil 18 and each tooth 16. Each coil 18 is constructed by covering strands made of, for example, copper, aluminum, silver, or alloys thereof with an insulating coating such as enamel. The strands are described as round wires here, but they may also be flat wires or hexagonal wires. When viewed from the radial direction of the stator core 12, the coil 18 is wound in a substantially elongated rectangular shape with the axial direction of the stator core 12 as its longitudinal side. In this embodiment, as an example, each coil 18 is constructed by winding two wires. The two wires may be wound simultaneously or separately.

[0020] As shown in Figures 3 and 4, each coil 18 has two coil terminals 181 at one end and two coil terminals 182 at the other end. In this embodiment, as an example, both the two coil terminals 181 and the two coil terminals 182 are led out to one side in the axial direction of the stator core 12. The two coil terminals 181 are located at the base of the teeth 16, and the two coil terminals 182 are located at the tip of the teeth 16. The two coil terminals 181 extend parallel to each other in the axial direction of the stator core 12 and are adjacent to each other (in this case, touching each other) in the circumferential direction of the stator core 12. Similarly, the two coil terminals 182 extend parallel to each other in the axial direction of the stator core 12 and are adjacent to each other (in this case, touching each other) in the circumferential direction of the stator core 12. The axial direction of the stator core 12 corresponds to the "first direction" in this invention, and the circumferential direction of the stator core 12 corresponds to the "second direction" in this invention. The two coil terminals 181 may be separated by a distance of approximately 10% or less of the coil diameter. The same applies to the two coil terminals 182. Furthermore, the coil terminals 181 and 182 may be configured to be close to the inner or outer diameter of the stator core 12, or the coil terminals 181 and 182 may be configured to be separated axially above and below the stator core 12.

[0021] The multiple coils 18 are composed of multiple (in this case, 8) U-phase coils 18U, multiple (in this case, 8) V-phase coils 18V, and multiple (in this case, 8) W-phase coils 18W. Along the circumferential direction of the stator core 12, the U-phase coils 18U, V-phase coils 18V, and W-phase coils 18W are arranged sequentially in that order. Each U-phase coil 18U, each V-phase coil 18V, and each W-phase coil 18W are mounted on the teeth 16 of the stator core 12 with spacing in the circumferential direction of the stator core 12. Adjacent coils 18 of the same phase (U-phase, V-phase, or W-phase) are electrically connected to each other by a busbar unit 20.

[0022] As shown in Figures 1 to 4, the busbar unit 20 is positioned on one side in the axial direction relative to the stator core 12. As shown in Figure 5, the busbar unit 20 comprises a first busbar 22, a second busbar 24, and an insulator 26. Both the first busbar 22 and the second busbar 24 correspond to the "busbar" in this invention. The first busbar 22 is composed of a U-phase busbar 22U, a V-phase busbar 22V, and a W-phase busbar 22W. The second busbar 24 is composed of, for example, a plurality (in this case, eight) of busbar segments 24S. The U-phase busbar 22U, V-phase busbar 22V, W-phase busbar 22W, and the busbar segments 24S are, for example, manufactured by press-forming metal plates, but are not limited to this. For example, similar to the coil 18, the U-phase busbar 22U, V-phase busbar 22V, W-phase busbar 22W, and busbar segment 24S may be manufactured using round wire, flat wire, hexagonal wire, etc. Furthermore, the configuration of the busbar unit 20 is merely an example and can be modified as appropriate.

[0023] The U-phase busbar 22U, V-phase busbar 22V, and W-phase busbar 22W each have a first extension portion 22U1, 22V1, and 22W1 that extend annularly in the circumferential direction of the stator core 12 along the yoke 14, and a plurality of first coil joint portions 22U2, 22V2, and 22W2 that extend from the first extension portions 22U1, 22V1, and 22W1 toward the root side of each tooth 16. The plurality of first coil joint portions 22U2, 22V2, and 22W2 all correspond to the "coil joint portion" in the present invention. Furthermore, the U-phase busbar 22U, V-phase busbar 22V, and W-phase busbar 22W each have U-phase terminal portions 22U3, V-phase terminal portions 22V3, and W-phase terminal portions 22W3 (see Figures 1 and 2) that extend radially outward from the first extension portions 22U1, 22V1, and 22W1 of the stator core 12. Alternatively, the U-phase terminal portions 22U3, V-phase terminal portions 22V3, and W-phase terminal portions 22W3 may be configured to extend axially outward from the first extension portions 22U1, 22V1, and 22W1 of the stator core 12.

[0024] The first extension portion 22U1 of the U-phase busbar 22U, the first extension portion 22V1 of the V-phase busbar 22V, and the first extension portion 221W1 of the W-phase busbar 22W are arranged concentrically with the stator core 12. The first extension portions 22U1, 22V1, and 22W1 are spaced apart from the radially outer side of the stator core 12. The first extension portions 22U1, 22V1, and 22W1 are located in the region that overlaps with the yoke 14 when viewed from the axial direction of the stator core 12. Note that the above positional relationship of the first extension portions 22U1, 22V1, and 22W1 in the radial direction of the stator core 12 is merely an example and can be changed as appropriate. Alternatively, multiple busbars may be arranged in the axial direction of the stator core 12.

[0025] The first coil joints 22U2, 22V2, and 22W2 extend from the first extensions 22U1, 22V1, and 22W1 toward the opposite side of the stator core 12, and then bend radially inward toward the stator core 12, with each tip positioned near the base of each tooth 16. The tip surfaces of the first coil joints 22U2, 22V2, and 22W2 face radially inward toward the stator core 12. The radial direction of the stator core 12 corresponds to the "third direction" in this invention. The axial direction, circumferential direction, and radial direction of the stator core 12 are orthogonal to each other.

[0026] As shown in Figure 6, two concave curved surfaces 23 (notation omitted outside of Figure 6) are formed on the end faces of the first coil joints 22U2, 22V2, and 22W2, respectively, in an arc shape that recesses radially outward from the stator core 12 when viewed from the axial direction of the stator core 12, and are arranged in the circumferential direction of the stator core 12. The outer surfaces of the two coil terminals 181 are in contact with the two concave curved surfaces 23, respectively. Each concave curved surface 23 is formed concentrically with the outer surface of each coil terminal 181.

[0027] Furthermore, each of the first coil joints 22U2, 22V2, and 22W2 is provided with an overhang 25 that contacts one coil terminal 181 from the opposite side of the other coil terminal 181 (i.e., one side in the circumferential direction of the stator core 12). As a result, each of the first coil joints 22U2, 22V2, and 22W2 is formed with an asymmetrical shape in the circumferential direction of the stator core 12. As will be described in detail later, each of the first coil joints 22U2, 22V2, and 22W2 is configured to have two coil terminals 181 welded to it. Alternatively, the two concave curved surfaces 23 may not be formed on the tip surfaces of each joint 22U2, 22V2, and 22W2. In that case, for example, each of the tip surfaces of each joint 22U2, 22V2, and 22W2 may be a flat surface, and the two coil terminals 181 will be in contact with this flat surface.

[0028] Each of the multiple busbar divisions 24S constituting the second busbar has a second extension portion 24S1 that extends in an arc shape in the circumferential direction of the stator core 12 along the yoke 14, and a plurality (in this case, three) of second coil joint portions 24S2 that extend from the second extension portion 24S1 toward the tip side of each tooth 16. The second extension portion 24S1 is positioned at a distance from the first extension portion 22W1 of the W-phase busbar 22W radially inward of the stator core 12 and is curved in an arc shape concentric with the stator core 12.

[0029] Multiple second coil joints 24S2 extend from the second extension 24S1 toward the opposite side of the stator core 12, then bend radially inward toward the stator core 12, with each tip positioned near the tip of each tooth 16. The tip surface of each second coil joint 24S2 faces radially inward toward the stator core 12. As shown in Figure 6, two concave curved surfaces 23 (notation omitted outside of Figure 6) are formed on the tip surface of each second coil joint 24S2, recessed in an arc shape radially outward toward the stator core 12 when viewed from the axial direction of the stator core 12, and are arranged circumferentially toward the stator core 12. The outer circumferential surfaces of two coil terminals 182 are in contact with the two concave curved surfaces 23, respectively. Each concave curved surface 23 is formed concentrically with the outer circumferential surface of each coil terminal 182.

[0030] Furthermore, the tip of the second coil joint 24S2 is provided with an overhang 25 that contacts one coil terminal 182 from the opposite side of the other coil terminal 182 (i.e., one side in the circumferential direction of the stator core 12). As a result, the tip of the second coil joint 24S2 is formed in an asymmetrical shape in the circumferential direction of the stator core 12. As will be described in detail later, two coil terminals 182 are welded to the tip of each second coil joint 24S2. Alternatively, the tip surface of the second coil joint 24S2 may not have two concave curved surfaces 23. In that case, for example, the tip surface of the second coil joint 24S2 may be a flat surface, and the two coil terminals 182 will contact this flat surface. Alternatively, the second busbar 24 may be formed as a single unit without being divided into multiple busbar segments 24S.

[0031] The insulator 26 is, for example, made of molded resin and is formed in an annular shape. This insulator 26 is fitted inside the case 28. This insulator 26 is made of a thermosetting resin such as epoxy resin or a thermoplastic resin, with a non-magnetic powder mixed in as a filler, and has thermal conductivity and insulating properties. The first extensions 22U1, 22V1, and 22W1 of the U-phase busbar 22U, V-phase busbar 22V, and W-phase busbar 22W, and the second extensions 24S1 of the multiple busbar divisions 24S are embedded in this insulator 26. The first extensions 22U1, 22V1, and 22W1 of the U-phase busbar 22U, V-phase busbar 22V, and W-phase busbar 22W, and the second extensions 24S1 of the multiple busbar divisions 24S are held by this insulator 26.

[0032] The configuration of the insulator 26 is not limited to the above and can be changed as appropriate. For example, the insulator 26 may be formed in an annular shape from a resin having thermal conductivity and insulating properties, and a plurality of annular grooves opening on one side in the axial direction of the stator core 12 may be formed concentrically, with the first extended portion 22U1, 22V1, 22W1 and the second extended portion 24S1 inserted and held in these annular grooves. Alternatively, for example, the insulator 26 may be integrated with an insulator (not shown) interposed between the stator core 12 and each coil 18.

[0033] Next, the main parts of this embodiment will be described. In the stator manufacturing method according to this embodiment, two coil terminals 181 are welded to the tip of each of the first coil joints 22U2, 22V2, and 22W2, and two coil terminals 182 are welded to the tip of the second coil joint 24S2. Since the welding of two coil terminals 181 to the tips of the first coil joints 22U2, 22V2, and 22W2 and the welding of two coil terminals 182 to the tip of the second coil joint 24S2 are basically the same, the following description will mainly focus on the welding of two coil terminals 181 to the tip of the first coil joint 22U2, and the description of welding at other locations will be omitted. In the following description, the first coil joint 22U2 may be simply referred to as "coil joint 22U2," and the U-phase busbar 22U may be simply referred to as "busbar 22U."

[0034] The welding described above uses an arc welding machine 40 shown in Figure 7. This arc welding machine 40 has a welding machine body 42, a torch 44, and a drive source (not shown) that drives the torch 44 up and down. The lower end of the torch 44 is provided with a tungsten electrode 46 and an outlet (not shown) for an inert gas, argon gas G. Below the tungsten electrode 46, two coil terminals 181 are positioned in contact with the coil joint 22U2 of the busbar 22U, facing radially outward from the stator core 12. The contact of the two coil terminals 181 with the coil joint 22U2 is performed, for example, using a jig provided on the arc welding machine 40.

[0035] In welding using the arc welding machine 40 described above, first, with the two coil terminals 181 in contact with the coil joint 22U2 facing radially outward from the stator core 12, the tungsten electrode 46 is brought into contact with one coil terminal 181 at a position closer to the other coil terminal 181 (see the position labeled WP1 in Figure 6) to check for conductivity. The reason for bringing the tungsten electrode 46 into contact with one coil terminal 181 is to ensure that the arc discharge is directed precisely in the intended direction and that the entire assembly is welded uniformly. This position is set, for example, to the area of ​​one-third of one coil terminal 181 closer to the other coil terminal 181. Furthermore, in the case of high-voltage arc welding, for example, it is not necessary to bring the tungsten electrode 46 and the coil terminal 181 into contact; they can simply be placed close together and facing each other. Even when they are separated, arc welding can be performed by applying a high-frequency voltage to cause dielectric breakdown of the air. Furthermore, in the case of high-voltage arc welding, for example, by performing three-dimensional image recognition, contact of the tungsten electrode 46 with one of the coil terminals 181 becomes unnecessary.

[0036] Next, the torch 44 is raised upward to generate an arc between one coil end 181 and the tungsten electrode 46. Then, after raising the torch 44 to a predetermined height, the main welding is performed. This welds the two coil ends 181 to the coil joint 22U2. The welding current is set to, for example, within the range of 100A to 300A, and the welding time is set to, for example, within the range of 0.1 seconds to 0.3 seconds.

[0037] During the welding described above, the volume of the coil joint 22U2 is set to be larger on the side of one coil terminal 181 (the coil terminal 181 labeled WP1 in Figure 6) than on the side of the other coil terminal 181. Specifically, in this embodiment, a protruding portion 25 is provided on the coil joint 22U2 that contacts one coil terminal 181 from the opposite side of the other coil terminal 181, so that the coil joint 22U2 is formed in an asymmetric shape in the circumferential direction (second direction) of the stator core 12. As a result, the combined volume of the two coil terminals 181 and the coil joint 22U2 is set to be larger on the side of one coil terminal 181 than on the side of the other coil terminal 181. Then, with the volume set as described above, the coil joint 22U2 and the two coil terminals 181 are welded together. Figure 8 shows a plan view of the surrounding area of ​​the weld 30 between the coil joint 22U2 and the two coil terminals 181, and Figure 9 shows a side view of the surrounding area of ​​the same weld 30. The volume of the two coil terminals 181 is the volume of the portion of the two coil terminals 181 that overlaps with the coil joint 22U2 when viewed from the radial direction (third direction) of the stator core 12, and the volume of the portion of the two coil terminals 181 that is closer to the tip than those portions.

[0038] The stator 10 is completed when the welding of two coil terminals 181 to multiple first coil joints 22U2, 22V2, and 22W2, and the welding of two coil terminals 182 to multiple second coil joints 24S2, are completed. In the completed stator 10, the U-phase terminals 22U3, V-phase terminals 22V3, and W-phase terminals 22W3 of the U-phase busbar 22U, V-phase busbar 22V, and W-phase busbar 22W are connected to a three-phase power supply. As a result, the stator 10 with the above configuration functions as a stator for a three-phase motor.

[0039] (Mechanism of Action and Effects) In this embodiment, the stator 10 is manufactured by welding two coil ends 181, which are led out from a coil 18 wound around the teeth 16 of the stator core 12, to a coil joint 22U2 of a busbar 22U. In this manufacturing method, two coil ends 181, each extending in the axial direction of the stator core 12 and touching each other in the circumferential direction of the stator core 12, are brought into contact with the tip surface of the coil joint 22U2 in the radial direction of the stator core 12. In this state, an arc is generated between one of the coil ends 181 and the tungsten electrode 46 of the arc welding machine 40, and the two coil ends 181 are welded to the coil joint 22U2. In other words, arc welding is performed targeting one of the two coil ends 181.

[0040] During the welding described above, the combined volume of the coil joint 22U2 is set to be larger on one coil end 181 side than on the other coil end 181 side. This allows the heat capacity, including the coil joint 22U2, to be equalized on both the one coil end 181 side and the other coil end 181 side when arc welding is performed targeting one coil end 181. As a result, the two coil ends 181 and the coil joint 22U2 can be melted evenly on both sides, making it possible to weld both coil ends 181 evenly to the U-phase busbar 22U in a single welding pass.

[0041] Furthermore, in this embodiment, the coil joint portion 22U2 of the U-phase busbar 22U is formed in an asymmetrical shape in the circumferential direction of the stator core 12. This makes it possible to set the volume of the coil joint portion 22U2 to be larger on one coil end 181 side than on the other coil end 181 side.

[0042] Furthermore, in this embodiment, a protruding portion 25 is provided on the coil joint portion 22U2 that contacts one coil terminal 181 from the opposite side of the other coil terminal 181. This allows the coil joint portion 22U2 to be formed in an asymmetrical shape in the circumferential direction of the stator core 12, and the volume of the coil joint portion 22U2 can be set to be larger on the side of one coil terminal 181 than on the side of the other coil terminal 181.

[0043] The effects of this embodiment will be supplemented by referring to the comparative example shown in Figures 10 and 11. In this comparative example, the coil joint 22U2 is provided with protrusions 25 on both sides in the circumferential direction of the stator core 12 for the two coil terminals 181, and the coil joint 22U2 is formed in a symmetrical shape in the circumferential direction of the stator core 12. The volume of the coil joint 22U2 is set to be the same on the side of one coil terminal 181 and the side of the other coil terminal 181. In this comparative example, if arc welding is performed targeting a position on one coil terminal 181 closer to the other coil terminal 181 (see the position labeled WP1 in Figure 10), as shown in Figure 11, the side of one coil terminal 181 melts preferentially, and the welded portion 30 is biased towards the side of one coil terminal 181, resulting in insufficient welding of the other coil terminal 181.

[0044] In the comparative example described above, arc welding can also be performed targeting a position near the midpoint between the two coil terminals 181 in the coil joint 22U2 (the position labeled WP2 in Figure 10). However, in this case, the two coil terminals 181 will melt near the position labeled WP2, but the entire area of ​​the two coil terminals 181 will not melt, resulting in insufficient welding. Furthermore, in the comparative example described above, the two protruding portions 25 of the coil joint 22U2 can be crimped together in a direction that brings them closer to each other to create electrical contact with the two coil terminals 181, and welding can be performed in this state. However, if there is variation in the strength of the crimping, the melting will easily propagate to the side of the two coil terminals 181 that is in stronger contact with the coil joint 22U2, resulting in inconsistent welding. For this reason, it is preferable to bring the coil joint 22U2 into contact with the two coil terminals 181 using a jig or the like, without crimping.

[0045] In this embodiment, since two coil terminals 181 can be evenly welded to the U-phase busbar 22U in a single welding operation, it is possible to shorten the manufacturing cycle while improving quality, durability, and manufacturing yield. Furthermore, since the crimping process is unnecessary, the manufacturing process can be simplified. In addition, since there is no need to secure space for inserting a crimping tool in the stator 10, space can be used more effectively.

[0046] Furthermore, in this embodiment, the first coil joints 22U2, 22V2, and 22W2 of the first busbar 22 are formed with first insertion portions 23 into which the coil terminals 181 of the coil 18 are inserted, and the second coil joint 24S2 of the second busbar 24 is formed with a second insertion portion 25 into which the coil terminals 182 of the coil 18 are inserted. This insertion stabilizes the positional relationship between the coil terminals 181 and 182 of the coil 18 and the first coil joints 22U2, 22V2, 22W2, and the second coil joint 24S2, making it easier to connect the coil terminals 181 and 182 to the first coil joints 22U2, 22V2, 22W2, and the second coil joint 24S2.

[0047] <Variation> Hereinafter, modifications of this embodiment will be described with reference to Figures 12 to 20. In Figures 12 to 20, the same reference numerals are used for components similar to those in the above embodiment. In Figures 13 and 15, SW is the wire of the coil 18, and IC is the insulating coating of the coil 18. In the first modification shown in Figures 12 and 13, the coil joint 22U2 is not formed in an asymmetrical shape, but rather the two wires constituting the coil 18 are set to different thicknesses, and the two coil terminals 181 are set to different thicknesses. For example, the diameter of one coil terminal 181 is set to φ2.0, and the diameter of the other coil terminal 181 is set to φ1.5. In this first modification, arc welding is performed targeting a position on one coil terminal 181 closer to the other coil terminal 181 (see the position labeled WP1 in Figure 12). As a result, the combined volume of the two coil terminals 181 and the coil joint 22U2 is set to be larger on one coil terminal 181 side than on the other coil terminal 181 side. In this first modified example as well, the heat capacity, including the coil joint 22U2, can be equalized on both the one coil terminal 181 side and the other coil terminal 181 side. As a result, the two coil terminals 181 and the coil joint 22U2 can be melted evenly on both sides, making it possible to evenly weld the two coil terminals 181 to the U-phase busbar 22U in a single welding operation. Although Figures 12 and 13 show a method of even welding by changing the diameter of the coil terminals 181, it is also possible to create a difference in heat capacity by changing the height (making the one welded first taller) while keeping the diameter of the two coil terminals 181 the same. It is also possible to create a difference in heat capacity by changing both the diameter and height of the coil terminals 181.

[0048] In the second modified example shown in Figures 14 and 15, the two wires constituting the coil 18 are set to the same thickness, but in the process of removing the insulating coating IC before welding, more wire is removed from the other coil terminal 181 than from the other coil terminal 181. As a result, the other coil terminal 181 is made thinner than the one coil terminal 181. In this second modified example, arc welding is performed targeting a position on one coil terminal 181 closer to the other coil terminal 181 (see the position labeled WP1 in Figure 14). In this second modified example as well, the heat capacity, including the coil joint 22U2, can be equalized on both the one coil terminal 181 side and the other coil terminal 181 side. As a result, the two coil terminals 181 and the coil joint 22U2 can be melted evenly on both sides, making it possible to evenly weld the two coil terminals 181 to the U-phase busbar 22U in a single welding operation.

[0049] The same effects and advantages as those of the above embodiment can be obtained in the first and second modified examples described above. Moreover, in the first and second modified examples described above, it is not necessary to make the coil joint portion 22U2 asymmetrical in shape, so there is no need to distinguish the orientation of the coil joint portion 22U2 during manufacturing, making manufacturing easier.

[0050] In the third modified example shown in Figures 16 and 17, the two coil terminals 181 are aligned radially on the stator core 12, and the two coil terminals 181 and the coil joint 22U2 are in contact with the stator core 12 in the circumferential direction. The same effects and advantages as in the above embodiment can be obtained in this third modified example as well.

[0051] In the fourth modified example shown in Figures 18 and 19, similar to the third modified example, the two coil terminals 181 are aligned radially on the stator core 12. The coil joint portion 22U2 is plate-shaped with the circumferential direction of the stator core 12 as the plate thickness direction, and contacts the two coil terminals 181 in the circumferential direction of the stator core 12. The tip of the coil joint portion 22U2 is an arc-shaped protrusion 25 that curves toward one side in the circumferential direction of the stator core, and contacts one coil terminal 181 from the opposite side to the other coil terminal 181. The same effects and advantages as in the above embodiment can be obtained in this fourth modified example as well. Note that Figures 16 and 18 illustrate an example in which the two coil terminals 181 are aligned radially on the stator core 12, but the two coil terminals 181 are Try arranging them diagonally with respect to the radial direction of the stator core 12.

[0052] The fifth modified example shown in Figure 20 is similar to the fourth modified example, but the two coil terminals 181 are aligned in the circumferential direction of the stator core 12, and the coil joint portion 22U2 is in radial contact with the two coil terminals 181 of the stator core 12. The same effects and advantages as in the above embodiment can be obtained with this fourth modified example as well.

[0053] In the sixth modified example shown in Figure 21, two coil ends 181 are brought into contact with the end face of the coil joint 22U2 using a jig 50. In this state, an arc is generated between one coil end 181 and the tungsten electrode 46 of the arc welding machine 40, and the two coil ends 181 are welded to the coil joint 22U2. During this welding, the combined volume of the two coil ends 181, the coil joint 22U2, and the jig 50 is set to be larger on the side of one coil end 181 than on the side of the other coil end 181. Specifically, the jig 50 is provided with an overhang 51 that contacts one coil end 181 from the opposite side from the other coil end 181, making the jig 50 asymmetrical in shape. This makes it possible to equalize the heat capacity, including the coil joint 22U2 and the jig 50, between one coil terminal 181 and the other coil terminal 181 when arc welding is performed targeting one coil terminal 181. The same effects as in the above embodiment can be obtained in this sixth modified example.

[0054] Although the present invention has been described above with reference to embodiments and several modifications, the present invention can be implemented with various modifications without departing from its spirit. Furthermore, it goes without saying that the scope of the present invention is not limited to the above embodiments and each of the above modifications.

[0055] Furthermore, the disclosure of Japanese Patent Application No. 2021-160056, filed on September 29, 2021, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually described as being incorporated by reference.

Claims

1. A method for manufacturing a stator, comprising welding two coil ends, which are derived from coils wound around the teeth of a stator core, to the coil joints of a busbar, A method for manufacturing a stator, wherein when an arc is generated between one of the coil terminals and the electrode of an arc welding machine to weld the two coil terminals to the coil joint, with the two coil terminals, each extending in a first direction and adjacent to each other in a second direction perpendicular to the first direction, in contact with the end face of the coil joint in a third direction perpendicular to the first and second directions, the combined volume of the two coil terminals and the coil joint is set to be larger on the side of one coil terminal than on the side of the other coil terminal.

2. The method for manufacturing a stator according to claim 1, wherein the coil joint portion is formed in an asymmetrical shape in the second direction.

3. The method for manufacturing a stator according to claim 2, wherein an overhang portion is provided at the coil joint portion that contacts one of the coil terminals from the opposite side to the other coil terminal.

4. A method for manufacturing a stator, comprising welding two coil ends, which are derived from coils wound around the teeth of a stator core, to the coil joints of a busbar, A method for manufacturing a stator, wherein when an arc is generated between one of the coil terminals and the electrode of an arc welding machine to weld the two coil terminals to the coil joint, with the two coil terminals, each extending in a first direction and adjacent to each other in a second direction perpendicular to the first direction, in contact with the end face of the coil joint using a jig in a third direction perpendicular to the first and second directions, the combined volume of the two coil terminals, the coil joint, and the jig is set to be larger on the side of one coil terminal than on the side of the other coil terminal.

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