Stator

Abstract

To provide a stator for which it is possible to easily determine the performance of welding between conductors, and a method for manufacturing the same.SOLUTION: A stator includes a stator core and a stator winding provided to the stator core. The stator winding consists of a plurality of rectangular conductor segments in which conductors 34 are covered with insulating coatings 35, and exposed portions 33 at which the conductors are exposed are formed at the tip portions of the conductor segments. At a coil end portion of the stator winding, the exposed portions of different conductor segments are connected by laser welding. The conductor width in a joint direction of the exposed portions is smaller on a laser irradiation side of each exposed portion on which laser irradiation of each exposed portion is performed than that on a non-irradiation side opposite to the laser irradiation side.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The disclosure of this specification relates to the fixation of rotating electrical machines. Child

Background Art

[0002] In the stator of a rotating electrical machine, a stator winding is provided on a stator core. The stator winding is configured by connecting a plurality of conductor segments made of, for example, rectangular conductors, such that the conductor segments are connected to each other. More specifically, an exposed portion with the insulating coating removed is provided at the tip of each conductor segment, and a configuration is known in which the exposed portions of different conductor segments are joined to each other and then connected by laser welding (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a configuration where the exposed portions of different conductor segments are connected by laser welding as described above, if the welding is not performed properly, there are concerns about inconveniences such as problems with energization in the stator winding. In this case, as a state where the welding is not proper, it is conceivable that the depth of the welding at the welded portion is insufficient. However, it has become difficult to confirm the depth of the welding, that is, the appearance of the welding, from the outside at the welded portion of the conductor segment.

[0005] The present invention has been made in view of the above problems, and its main object is to provide a stator and a method for manufacturing the same that can easily determine the appearance of the welding between conductors.

Means for Solving the Problems

[0006] The stator of means 1 includes a stator core and a stator winding provided on the stator core. The stator winding is composed of a plurality of flat conductors in which the conductors are covered with an insulating film. An exposed portion where the conductor is exposed is formed at the tip of the conductor. At the coil end portion of the stator winding, the exposed portions of the different conductors are connected by laser welding. It is characterized in that the conductor width in the joining direction of the exposed portions is smaller on the laser irradiation side, which is the side where the laser irradiation of each exposed portion is performed, than on the anti-irradiation side, which is the opposite side.

[0007] In a configuration where the exposed portions of the conductors are joined by laser welding, the melting degree by the laser is different between the laser irradiation side where the laser irradiation is performed at the joining portion of the exposed portions and the anti-irradiation side which is the opposite side, and the melting degree is larger on the laser irradiation side. Regarding the non-melted portion in the joining direction of the exposed portions in each exposed portion, the non-melted range is smaller on the laser irradiation side and larger on the anti-irradiation side. In this case, when joining the exposed portions, it is considered that the exposed portions approach each other according to the melting degree at the joining portion of the exposed portions. In other words, it is considered that the side surfaces on the side opposite to the joining surface approach each other in each exposed portion. Also, considering that the melting degree by the laser is different between the laser irradiation side and the anti-irradiation side, it is considered that a difference occurs in the conductor width in the joining direction of the exposed portions between the laser irradiation side and the anti-irradiation side. Here, since a difference in the melting degree in the laser irradiation direction correlates with the depth of the laser welding, the depth of the laser welding can be grasped from the dimensional change due to melting in each exposed portion.

[0008] In this regard, in the stator configured as described above, in the stator winding, exposed portions of conductor wires formed of straight wires are welded together, and the conductor width in the joining direction of the exposed portions is smaller on the laser irradiation side, which is the side where laser irradiation of each exposed portion is performed, than on the opposite side, the anti-irradiation side. In this configuration, the fact that the conductor width on the laser irradiation side is smaller than the conductor width on the anti-irradiation side means that melting at each exposed portion has been appropriately performed. Therefore, it is possible to provide a stator in which proper laser welding has been performed.

[0009] In means 2, at the joining boundary portion where the exposed portions are joined together, a raised portion formed of a molten conductor is formed on the laser irradiation side.

[0010] In two mutually joined exposed portions, the conductor width on the laser irradiation side is smaller than the conductor width on the anti-irradiation side, and a raised portion formed of a molten conductor is formed on the laser irradiation side. From this configuration, it can be seen that the raised portion has been formed on the laser irradiation side due to melting of the conductor. That is, it can be seen that melting of the conductor has progressed on the laser irradiation side, and the exposed portions have come closer to each other, resulting in an overhang of the molten conductor. Therefore, the raised portion serves as a mark indicating that melting at each exposed portion has been appropriately performed. As a result, it becomes possible to grasp the state of welding from the appearance.

[0011] In means 3, the stator winding is provided in a state where the conductor wires are accommodated in multiple layers in the radial direction in the slots of the stator core, and at the coil end portion, a plurality of axial end portions formed by connecting the exposed portions are arranged so as to be aligned in the radial direction and the circumferential direction, and each of the exposed portions at the axial end portion is connected by laser welding in a state of being radially overlapped.

[0012] In the stator with the above configuration, the conductors are accommodated in multiple layers in the radial direction in the slots of the stator core, and a plurality of axial end portions formed by connecting the exposed portions of the conductors at the coil end portions are arranged side by side in the circumferential direction and the radial direction. In such a configuration, in the coil end portion, the axial end portions are arranged in a state of being separated from each other, but the separation distance between the axial end portions in the radial direction is shorter than the separation distance in the circumferential direction.

[0013] In this regard, in each exposed portion at the axial end portion, since the conductor width on the laser irradiation side is smaller than the conductor width on the anti-irradiation side, compared with the configuration in which the conductor width on the laser irradiation side is the same as the conductor width on the anti-irradiation side, the separation distance (insulation distance) between the axial end portions can be increased. In particular, in the configuration in which the exposed portions are connected by laser welding in a state of being overlapped in the radial direction, the axial end portions are closer to each other compared with the configuration in which the exposed portions are overlapped in the circumferential direction, but even in such a configuration, appropriate insulation can be realized.

[0014] In means 4, the coil end portion is configured by connecting the tip portion of the conductor extending in a certain direction in the circumferential direction on the outer side in the axial direction of the stator core and the tip portion of the other conductor extending in a direction opposite to the certain direction in the circumferential direction. The exposed portions are respectively formed at the tip portions of the conductors extending from opposite sides in the circumferential direction, and the exposed portions are connected by laser welding. The conductor width in the joining direction of the exposed portions is smaller on the laser irradiation side than on the anti-irradiation side.

[0015] In the configuration in which the exposed portions are respectively formed at the tip portions of the conductors (circumferential tip portions) extending from opposite sides in the circumferential direction and the circumferential tip portions are connected by laser welding, compared with the configuration in which the tip portions including the exposed portions in each conductor extend in the axial direction and the tip portions extending in the axial direction (axial tip portions) are connected by laser welding, it is considered that it becomes even more difficult to confirm the welding depth. In this regard, since the conductor width on the laser irradiation side is smaller than the conductor width on the anti-irradiation side after laser welding, the welding depth can be appropriately confirmed, and thus the quality of the stator winding can be improved.

[0016] In means 5, a resin-sealed portion is provided with an insulating resin in a range including the exposed portion in the axial direction at the coil end portion.

[0017] A resin-sealed portion is provided with an insulating resin in a range including the exposed portion in the axial direction at the coil end portion. Thereby, the insulation between the conducting wires can be maintained in a good state.

[0018] In means 6, the stator winding is provided in a state where the conducting wires are accommodated in multiple layers in the radial direction in the slots of the stator core. In the coil end portion, a plurality of axial end portions formed by connecting the exposed portions are arranged so as to be aligned in the radial direction and the circumferential direction. The resin-sealed portion seals the plurality of axial end portions together and forms an annular shape extending along the axial end face of the stator core. The inner peripheral side surface on the radially inner side and the outer peripheral side surface on the radially outer side in the resin-sealed portion are inclined with respect to the axial direction in a direction approaching each other on the outer side in the axial direction. At the exposed portion of the axial end portion that is the most radially inner among the plurality of axial end portions aligned in the radial direction and the exposed portion of the axial end portion that is the most radially outer, the surfaces facing the inner peripheral side surface and the outer peripheral side surface of the resin-sealed portion are inclined with respect to the axial direction in the same direction as those inner peripheral side surface and outer peripheral side surface.

[0019] In a configuration where a plurality of axial ends, formed by connecting exposed portions of a conductor, are arranged side by side in the radial and circumferential directions at the coil end portion, since the plurality of axial ends are collectively sealed and a resin sealing portion is provided so as to form an annular shape along the axial end surface of the stator core, a resin sealing portion can be appropriately provided for a large number of axial ends in the coil end portion. Further, in the exposed portions of the axial end portion that is the innermost in the radial direction and the exposed portion of the axial end portion that is the outermost in the radial direction among the plurality of axial ends arranged in the radial direction, the surfaces facing the inner peripheral side surface and the outer peripheral side surface of the resin sealing portion are inclined with respect to the axial direction in the same direction as those inner peripheral side surface and outer peripheral side surface. Thereby, it is possible to make uniform the thickness of the insulating resin up to the exposed portion on the inner peripheral side and the outer peripheral side of the resin sealing portion. Therefore, even if a difference in thermal expansion occurs between the conductor and the insulating resin according to the difference in the linear expansion coefficient, the load acting on the exposed portion can be equalized. Thereby, the stator winding can be protected.

[0020] In means 7, between the two exposed portions connected by welding, there are a welded portion formed by a molten conductor and a non-welded portion where the non-molten conductors face each other, and the non-welded portions of the respective exposed portions are in contact with each other.

[0021] In the configuration where each exposed portion is sealed with an insulating resin in the coil end portion, if the insulating resin enters between the two exposed portions connected by welding, there is a concern that shear may occur in the welded portion between the exposed portions due to the difference in the linear expansion coefficient between the conductor and the insulating resin. In this regard, since the non-welded portions are in contact with each other between the two exposed portions connected by welding, it is possible to suppress the shear of the welded portion caused by the difference in the linear expansion coefficient between the conductor and the insulating resin.

[0022] Means 8 includes a stator core and a stator winding provided on the stator core. The stator winding is composed of a plurality of flat conductors in which the conductor is covered with an insulating coating. An exposed portion where the conductor is exposed is formed at the tip of the conductor. A method for manufacturing a stator in which exposed portions of different ones of the conductor wires are connected by welding at the coil end portion of the stator winding, an assembling step of assembling the conductor wires to the stator core, and after the assembling, a welding step of welding the exposed portions of different ones of the conductor wires by laser irradiation at the coil end portion, characterized in that, in the welding step, while the exposed portions are in a pressure-bonded state, laser irradiation is performed on the joint portion of the exposed portions, and the conductor width in the joining direction of the exposed portions is made smaller on the laser irradiation side, which is the side where the laser irradiation of each exposed portion is performed, than on the opposite side, which is the anti-irradiation side.

[0023] In the welding step during the manufacture of the stator, while the exposed portions of the conductor wires are in a pressure-bonded state, laser irradiation is performed on the joint portion of the exposed portions, and the conductor width in the joining direction of the exposed portions is made smaller on the laser irradiation side, which is the side where the laser irradiation of each exposed portion is performed, than on the opposite side, which is the anti-irradiation side. In this case, considering that the degree of melting by the laser is different between the laser irradiation side and the anti-irradiation side at the joint portion of the exposed portions, and that the degree of melting in the laser irradiation direction correlates with the depth of the laser welding, the depth of the laser welding can be grasped by the dimensional change due to melting at each exposed portion. That is, the fact that the conductor width on the laser irradiation side is smaller than the conductor width on the anti-irradiation side means that melting at each exposed portion has been properly performed. Thereby, a stator in which proper laser welding has been performed can be provided.

[0024] In means 9, after welding in the welding step, there is an inspection step of inspecting the welded portion of the exposed portions by comparing the conductor width on the laser irradiation side and the conductor width on the anti-irradiation side.

[0025] While considering that the difference in the conductor width between the laser irradiation side and the anti-irradiation side changes according to the welding depth, the appearance of the welded portion can be properly managed.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Modes for Carrying Out the Invention

[0027] Hereinafter, embodiments of the rotating electrical machine according to the present invention will be described with reference to the drawings. In the following embodiments and modifications, parts that are identical or equivalent to each other are denoted by the same reference numerals in the drawings, and the description of the parts with the same reference numerals is incorporated herein. The motor as the rotating electrical machine of this embodiment is used, for example, as an electric motor for a vehicle or an electric motor for an aircraft.

[0028] (First Embodiment) The rotating electrical machine of this embodiment can be applied to a permanent magnet synchronous motor, a wound field type, an induction machine, etc., and is a rotating electrical machine having a three-phase winding. The rotating electrical machine includes a cylindrical stator 10 shown in FIG. 1 and a rotor (not shown) disposed radially inside the stator 10. The rotor is rotatably disposed with respect to the stator 10 about the rotation axis. Hereinafter, the axial direction refers to the axial direction of the stator 10, that is, the axial direction of the rotation axis of the rotor, the radial direction refers to the radial direction of the stator 10, that is, the direction passing through the center of the rotation axis of the rotor and orthogonal to the rotation axis, and the circumferential direction refers to the circumferential direction of the stator 10, that is, the circumferential direction centered on the rotation axis of the rotor.

[0029] As shown in FIGS. 1 and 2, the stator 10 includes an annular stator core 11 and a stator winding 12 wound around the stator core 11. The rotating electrical machine of this embodiment is an inner rotor type rotating electrical machine, and the rotor is disposed rotatably radially inside the stator 10. The stator winding 12 is a three-phase winding having a U-phase winding, a V-phase winding, and a W-phase winding as phase windings for each phase. In the stator winding 12, the range overlapping the stator core 11 in the axial direction is the in-slot coil portion CS, and the portions on both axial sides and axially outside the stator core 11 are the coil end portions CE1 and CE2.

[0030] As shown in FIG. 3, the stator core 11 has an annular back yoke 21 and a plurality of teeth 22 protruding radially inward from the back yoke 21 and arranged at a predetermined distance in the circumferential direction. Slots 23 are formed between adjacent teeth 22. The slots 23 have an opening shape extending in the radial direction as the longitudinal direction and are provided at equal intervals in the circumferential direction in the stator core 11. And the stator winding 12 is provided in a state of being wound around the slots 23. The stator core 11 is configured as a core sheet laminate in which core sheets made of electromagnetic steel sheets, which are magnetic materials for example, are laminated in the axial direction.

[0031] The stator winding 12 is configured by connecting three-phase windings by a Y-connection (star connection). The stator winding 12 generates a magnetic flux when electric power (alternating current power) is supplied from a power source via an inverter (not shown). The stator winding 12 is configured using a plurality of conductor segments 30 as substantially U-shaped divided conductors. Hereinafter, the segment structure of the stator winding 12 will be described in detail.

[0032] FIG. 4 is a perspective view showing a conductor segment 30 and a part of the stator core 11. As shown in FIG. 4, the conductor segment 30 has a substantially U shape and has a pair of linear portions 31 that are linear and a turn portion 32 that is bent to connect the pair of linear portions 31. The pair of linear portions 31 have a length longer than the axial thickness of the stator core 11. The conductor segment 30 is configured using a flat wire in which a conductor having a rectangular cross section (a conductor having a pair of opposing planar portions) is coated with an insulating film, and the tip of each linear portion 31 is an exposed portion 33 where the conductor is exposed by removing the insulating film.

[0033] A plurality of conductor segments 30 are inserted into the slots 23 of the stator core 11 in a state where they are arranged in a line in the radial direction. In the present embodiment, the slots 23 are configured to accommodate the straight portions 31 of the conductor segments 30 in a state where they are stacked in seven layers. In the conductor segment 30, a pair of straight portions 31 are respectively accommodated in two slots 23 separated by a predetermined coil pitch. Among the straight portions 31, the portions accommodated in the slots 23 correspond to the in-slot coil portions CS of the stator winding 12. Note that an insulating sheet 24 for electrically insulating between the stator core 11 and the stator winding 12 (conductor segment 30) is provided in the slots 23. The insulating sheet 24 is bent so as to collectively surround the plurality of conductor segments 30 inserted into the slots 23, and is provided in a state of being sandwiched between the inner peripheral surface (inner wall surface) of the stator core 11 and the conductor segment 30 in the slots 23.

[0034] A pair of straight portions 31 of the conductor segment 30 are respectively accommodated in two slots 23 with their radial positions shifted by one. For example, when one straight portion 31 is accommodated at the n-th position from the radially inner side (back yoke side), the other straight portion 31 is accommodated at the (n + 1)-th position from the radially inner side.

[0035] When inserting each conductor segment 30 into the slots 23 of the stator core 11, the straight portion 31 of each conductor segment 30 is inserted from the first end side among the first end side and the second end side at both axial ends of the stator core 11, and the tip of the straight portion 31 protrudes from the second end side. In this case, at the first end side of the stator core 11, one coil end portion CE1 is formed by the turn portion 32 of the conductor segment 30. At the second end side of the stator core 11, the anti-turn portion sides of the straight portions 31 are bent in the circumferential direction, and the straight portions 31 of different conductor segments 30 are connected to each other, thereby forming the other coil end portion CE2. The outlines of the coil end portions CE1 and CE2 are as shown in FIG. 2.

[0036] FIG. 5 is a perspective view showing a state in which a plurality of conductor segments 30 are connected to each other. In the conductor segment 30, on the side of the return portion of the pair of straight portions 31 (the upper end portion in the figure), there are a bridging portion 30a extending in the circumferential direction and a conductor tip portion 30b bent from the bridging portion 30a and extending in the axial direction, and an exposed portion 33 is provided at the conductor tip portion 30b. And in a state where the exposed portions 33 of the conductor tip portions 30b in different conductor segments 30 are joined to each other in the radial direction, these exposed portions 33 are connected by laser welding. Note that the conductor segments 30 include those in which the bridging portion 30a is bent to the same side as the turn portion 32 and those in which the bridging portion 30a is bent to the side opposite to the turn portion 32 on the side of the return portion of each straight portion 31.

[0037] In terms of FIG. 3, in the coil end portion CE2, the conductor segment 30 protrudes from the axial end face (the upper end face in the figure) of the stator core 11 and is bent in the circumferential direction so as to obliquely travel with a predetermined angle with respect to the core end face. Also, by joining the exposed portions 33 of the tip portions (conductor tip portions 30b) of different conductor segments 30 by laser welding, a plurality of conductor segments 30 are connected. In the coil end portion CE2, the axial end portion AX of the stator winding 12 is formed by connecting the exposed portions 33 to each other, and a plurality of axial end portions AX are arranged side by side in the radial direction and the circumferential direction.

[0038] FIG. 6 is a front view showing an enlarged configuration near the exposed portion 33 in the conductor segment 30. The conductor segment 30 has a linear conductor 34 and an insulating coating 35 covering the conductor 34, and the portion where the conductor 34 is exposed at the conductor tip portion 30b is the exposed portion 33. In each conductor segment 30, the bridging portion 30a extends in the circumferential direction (the left - right direction in the figure), while the conductor tip portion 30b extends in the axial direction (the up - down direction in the figure), and the exposed portions 33 are connected by welding in a state where they overlap in the radial direction (the direction orthogonal to the drawing plane).

[0039] In FIG. 6, W is a welded portion formed by melting the conductor 34. At the joint portion between the exposed portions 33, laser welding is performed by irradiating the laser from the anti-core side in the upper direction of the figure, that is, in the axial direction. That is, the vertical direction of the figure is the laser irradiation direction, the upper side of the figure in the exposed portion 33 is the laser irradiation side, and the lower side is the anti-irradiation side.

[0040] By the way, in a configuration where the exposed portions 33 of the conductor segments 30 are welded to each other, it is considered difficult to confirm from the appearance the depth of the welding, that is, the quality of the welding, at the welded portion W. In this regard, in the present embodiment, the degree of melting of the conductor 34 is different in the depth direction (laser irradiation direction) of the welding at the welded portion W, the degree of melting is large on the laser irradiation side, and the degree of melting is small on the anti-irradiation side. Furthermore, paying attention to the fact that the conductor width in the joining direction of the exposed portions 33 (conductor joining direction) differs in the axial direction due to the difference in the degree of melting of the conductor 34, the depth of the welding can be determined according to the conductor width in the conductor joining direction.

[0041] Hereinafter, the configuration regarding the welding of the exposed portion 33 of the conductor segment 30 will be described in more detail. FIG. 7 is a longitudinal sectional view obtained by cutting each exposed portion 33 of the conductor segment 30 in a direction crossing the joint portion, and this corresponds to a sectional view taken along line 7-7 in FIG. 6. In FIG. 7, the left-right direction is the radial direction.

[0042] As shown in FIG. 7, at the tip of the conductor segment 30, the portion between the exposed portions 33 forms a welded portion W, and the welded portion W is formed from the upper part of the exposed portion 33 on the laser irradiation side toward the lower part of the exposed portion 33 on the anti-irradiation side. In each exposed portion 33, the welded portion W is the portion where the conductor 34 is melted during laser welding, and the portion other than the welded portion W is the non-melted portion. In this case, in the axial direction, the non-melted range in the conductor joining direction is small (i.e., the melted range is large) on the laser irradiation side, and the non-melted range in the conductor joining direction is large (i.e., the melted range is small) on the anti-irradiation side. As a result, the conductor width in the conductor joining direction is different in the axial direction, and the conductor width L1 on the laser irradiation side is smaller than the conductor width L2 on the anti-irradiation side (L1 < L2). In this configuration, the fact that the conductor width L1 on the laser irradiation side is smaller than the conductor width L2 on the anti-irradiation side means that the melting at each exposed portion 33 was properly performed. Therefore, according to the conductor widths L1 and L2 at the exposed portions 33 joined to each other, it is possible to confirm that proper laser welding has been performed.

[0043] In addition to the welded portion W formed by the melted conductor existing between the two exposed portions 33 connected by welding, there are non-welded portions UW where the non-melted conductors face each other. In this case, the non-welded portions UW of each exposed portion 33 are in contact with each other, and therefore, there is no gap between the two exposed portions 33. Here, it is preferable that the welded portion W is provided in a range of at least 1 / 2 of the exposed portion 33 in the axial direction (laser irradiation direction), and the exposed portions 33 are in contact with each other at the non-welded portion UW which is the remaining range.

[0044] Also, at the joining boundary portion where the exposed portions 33 are joined, a raised portion 36 made of melted conductor is formed on the laser irradiation side. This raised portion 36 is a bulging portion formed by the surplus conductor accompanying the fact that the conductor width L1 on the laser irradiation side is smaller than the conductor width L2 on the anti-irradiation side in the two exposed portions 33 joined to each other.

[0045] FIG. 8 is a diagram showing a state in which a plurality of axial ends AX are arranged radially in the coil end portion CE2. As described above, in the two joined exposed portions 33, the conductor width L1 on the laser irradiation side is smaller than the conductor width L2 on the anti-irradiation side. Therefore, the axial ends AX each composed of a pair of two exposed portions 33 have an increased separation distance in the radial direction, and the insulation performance is improved.

[0046] Each conductor segment 30 is accommodated in each slot 23 arranged in the circumferential direction, while being provided in a state of being arranged in multiple layers in the radial direction in each slot 23. In this case, when comparing the separation distance between the axial ends AX in the circumferential direction and the separation distance between the axial ends AX in the radial direction, the latter (the separation distance in the radial direction) is shorter. Therefore, there is a concern about unintentional insulation defects for the axial ends AX arranged in the radial direction.

[0047] In this regard, in the present embodiment, the exposed portions 33 are welded in a state where they are joined in the radial direction, and for the conductor widths of the two joined exposed portions 33, the conductor width L1 on the laser irradiation side is smaller than the conductor width L2 on the anti-irradiation side. Therefore, compared with a configuration in which the conductor width L1 on the laser irradiation side has the same dimension as the conductor width L2 on the anti-irradiation side, the separation distance between the axial ends AX in the radial direction can be widened. In particular, in the configuration of the present embodiment in which the exposed portions 33 are connected by laser welding in a state where they are overlapped in the radial direction, although the axial ends AX are closer to each other compared with a configuration in which the exposed portions 33 are overlapped in the circumferential direction, even in such a configuration, appropriate insulation can be realized.

[0048] The coil end portion CE2 is sealed with an insulating resin, and its configuration is shown in FIGS. 9 and 10. FIG. 10 shows a state in which the axial ends AX formed by connecting the exposed portions 33 are arranged radially, and the resin sealing portion 41 is indicated by a virtual line. As shown in these figures, an annular resin sealing portion 41 is provided in the coil end portion CE2 with an insulating resin.

[0049] As shown in FIG. 10, the resin sealing portion 41 is provided in a range including the exposed portion 33 of the conductor segment 30 in the axial direction. That is, the axial range of the resin sealing portion 41 includes the exposed portion 33 in the conductor segment 30 and extends to a position away from the axial end face of the stator core 11. In this case, since a resin-sealing-free region is provided between the resin sealing portion 41 and the core end face, it is possible to use that region as a coil cooling portion for cooling the stator winding 12. Note that as cooling of the stator winding 12, cooling using cooling oil or cooling water as a refrigerant (oil cooling, water cooling), cooling by air (air cooling), etc. are assumed.

[0050] The resin sealing portion 41 collectively seals a plurality of axial end portions AX arranged in the radial direction and circumferential direction, and has an annular shape extending along the axial end face of the stator core 11. In the resin sealing portion 41, the side surfaces 41a and 41b on both sides in the radial direction are the inner circumferential side surface on the inner side in the radial direction and the outer circumferential side surface on the outer side in the radial direction, respectively, and these side surfaces 41a and 41b are inclined with respect to the axial direction in a direction approaching each other on the outer side in the axial direction. The inclination of each side surface 41a, 41b of the resin sealing portion 41 is the draft gradient during the formation of the sealing portion. And in the exposed portion 33 of the axial end portion AX that is the innermost in the radial direction and the exposed portion 33 of the axial end portion AX that is the outermost in the radial direction among the plurality of axial end portions AX arranged in the radial direction, the surfaces facing the respective side surfaces 41a, 41b of the resin sealing portion 41 are inclined with respect to the axial direction in the same direction as these side surfaces 41a, 41b.

[0051] In this case, the side surfaces 41a and 41b on both radial sides are provided in an inclined direction with respect to the axial direction, and the inclination angle may be adjusted to match the inclination angle of the exposed portion 33. That is, each side surface 41a, 41b of the resin sealing portion 41 is such that the insulation resin thicknesses D1 and D2 are uniform with respect to the exposed portion 33 of the axial end portion AX that is the innermost in the radial direction and the exposed portion 33 of the axial end portion AX that is the outermost in the radial direction among the axial end portions AX arranged in the radial direction. Thereby, even if a difference in thermal expansion occurs between the conductor 34 and the insulating resin of the resin sealing portion 41 according to the difference in the linear expansion coefficient, the load acting on the exposed portion 33 can be equalized.

[0052] Also, as described above, between the two exposed portions 33 connected by welding, there are a welded portion W formed by the molten conductor and a non-welded portion UW where the non-molten conductors face each other, and the non-welded portions UW of the respective exposed portions 33 are in contact with each other. Therefore, no insulating resin enters between the two exposed portions 33 at each axial end portion AX, and inconveniences such as shear occurring in the welded portion W between the exposed portions 33 due to the difference in the linear expansion coefficient between the conductor and the insulating resin are suppressed.

[0053] Next, a method for manufacturing the stator 10 will be described. The manufacturing method generally includes an assembling step of assembling the conductor segment 30 to the stator core 11, a welding step of laser-welding the exposed portions 33 by irradiating a laser to the joint portion between the exposed portions 33 of the conductor segment 30, and an inspection step after welding.

[0054] In the assembling step, a plurality of conductor segments 30 are inserted into each slot 23 of the stator core 11. Also, at one axial end side, the protruding portion of the straight portion 31 of the conductor segment 30 is bent in the circumferential direction so that the exposed portions 33 of different conductor segments 30 face each other in the radial direction.

[0055] In the welding process, laser welding is performed by irradiating a laser on the joint portion between the exposed portions 33 of the conductor segments 30. FIGS. 11(a) to 11(c) are diagrams showing changes in the states of the respective exposed portions 33 when performing laser welding.

[0056] In FIG. 11(a), the exposed portions 33 of the respective conductor segments 30 are in a state of facing each other in the radial direction. This is the state immediately before welding. In each exposed portion 33, the conductor width in the joining direction (the left - right direction in the figure) is the same at any position in the axial direction. In this state, the side surfaces 33a on the side opposite to the joining surfaces of the respective exposed portions 33 are substantially parallel to each other. Although in FIG. 11(a), the inner opposing surfaces of the exposed portions 33 are separated from each other, for example, by expanding the conductor exposure range at least inside each exposed portion 33, it is also possible to bring the opposing surfaces of the exposed portions 33 into contact with each other.

[0057] Thereafter, as shown in FIG. 11(b), laser welding is performed with a pair of pressing plates PL pressed against the respective side surfaces 33a of the two exposed portions 33. At this time, with the exposed portions 33 pressed against each other by the pair of pressing plates PL, a laser is irradiated from the outside in the axial direction onto the joint portion between the exposed portions 33. As a result, the exposed portions 33 melt with the laser irradiation, and the melting range gradually expands downward in the axial direction. Also, because the exposed portions 33 are pressed against each other, as the exposed portions 33 melt, the exposed portions 33 move closer to each other on the side where they approach each other.

[0058] Here, the depth of laser welding, that is, the axial depth of the molten pool formed by the accumulation of the molten conductor, is correlated with the difference in the melting amounts on the laser - irradiated side and the anti - irradiated side. Specifically, the deeper the depth of laser welding (the depth of the molten pool), the larger the melting amount on the laser - irradiated side, and the larger the difference in the melting amounts between the laser - irradiated side and the anti - irradiated side. Also, according to the difference in the melting amounts between the laser - irradiated side and the anti - irradiated side, the degree to which the exposed portions 33 approach each other changes, and the distance between the side surfaces 33a on the anti - joining side of each exposed portion 33 changes.

[0059] Then, as shown in FIG. 11(c), when the deepest part of the welding reaches near the end of the exposed portion 33, that is, when the welding depth becomes approximately the same as the axial length of the exposed portion 33, the laser welding is terminated. At this time, in the joining direction of the exposed portions 33, the conductor width L1 on the laser irradiation side is smaller than the conductor width L2 on the anti-irradiation side. Also, at the joining boundary where the exposed portions 33 are joined to each other, it is assumed that there are non-welded portions UW where the unfused conductors face each other, but the non-welded portions UW of each exposed portion 33 are in contact with each other, and there is no gap between the two exposed portions 33. In the conductor segment 30, the insulating coating 35 near the boundary of the exposed portion 33 is melted by the heat of the laser, and the exposed portions 33 are in contact with each other. In the welding process, the welding conditions such as the intensity of the laser may be adjusted according to the ratio of the desired conductor widths L1 and L2.

[0060] Also, during laser welding, due to the pressure contact of the exposed portions 33 with each other, the exposed portions 33 approach each other on the laser irradiation side, causing the molten conductor to protrude axially outward, and a raised portion 36 is formed.

[0061] After the completion of the laser welding, the welded portion W of the exposed portions 33 is inspected by comparing the conductor width L1 on the laser irradiation side and the conductor width L2 on the anti-irradiation side (inspection process). At this time, since the conductor width L1 on the laser irradiation side is smaller than the conductor width L2 on the anti-irradiation side, and the ratio of these conductor widths L1 and L2 is within a predetermined range, it is determined that the depth of the laser welding is the desired depth and the melting at each exposed portion 33 has been properly performed.

[0062] Thereafter, a resin sealing portion 41 is formed at the coil end portion CE2. For example, the coil end portion CE2 may be immersed in a sealing portion forming container containing a liquid resin material, and the resin sealing portion 41 may be formed in that state. At this time, as described above, since there is no gap between the two exposed portions 33, the entry of the resin material between the exposed portions 33 is suppressed.

[0063] According to the above embodiment, it has the following excellent effects.

[0064] In a configuration where the exposed portions 33 are welded together, a difference in the amount of melting occurs between the laser irradiation side and the anti-irradiation side on the joint surface in correlation with the depth of laser welding, and a change occurs in the conductor width between the exposed portions 33 according to the amount of melting. Therefore, the depth of laser welding of the exposed portions 33 can be grasped from the change in the conductor width. In this regard, in the stator winding 12, the exposed portions 33 of the conductor segments 30 are welded together, and the conductor width in the joining direction of the exposed portions 33 is smaller on the laser irradiation side, which is the side where the laser irradiation of each exposed portion 33 is performed, than on the anti-irradiation side, which is the opposite side. In this configuration, the fact that the conductor width L1 on the laser irradiation side is smaller than the conductor width L2 on the anti-irradiation side means that melting at each exposed portion 33 has been properly performed. Therefore, a stator 10 in which proper laser welding has been performed can be provided.

[0065] In two mutually joined exposed portions 33, the conductor width L1 on the laser irradiation side is smaller than the conductor width L2 on the anti-irradiation side, and a raised portion 36 made of a molten conductor is formed on the laser irradiation side. In this configuration, it can be seen that the raised portion 36 has been formed on the laser irradiation side due to the melting of the conductor. That is, it can be seen that melting of the conductor has progressed on the laser irradiation side, and the exposed portions 33 have moved closer to each other, resulting in the overflow of the molten conductor. Therefore, the raised portion 36 serves as a mark indicating that melting at each exposed portion 33 has been properly performed. Thereby, it becomes possible to grasp the welding state from the appearance.

[0066] Since the conductor width L1 on the laser irradiation side is smaller than the conductor width L2 on the anti-irradiation side with respect to the conductor width in the joining direction of the exposed portions 33, the separation distance (insulation distance) between the respective axial end portions AX can be increased as compared with a configuration in which the conductor width L1 on the laser irradiation side has the same dimension as the conductor width L2 on the anti-irradiation side. In particular, in a configuration where the respective exposed portions 33 are connected by laser welding in a state of being radially overlapped, although the respective axial end portions AX are closer to each other as compared with a configuration in which the respective exposed portions 33 are circumferentially overlapped, even in such a configuration, proper insulation can be realized.

[0067] In the coil end portion CE2, a resin sealing portion 41 is provided with an insulating resin in a range including the exposed portion 33 in the axial direction. Thereby, the insulation between the conductor segments 30 can be maintained in a good state.

[0068] In the configuration where the axial end portion AX of the stator winding 12 is arranged in the coil end portion CE2 so as to be aligned in the radial direction and the circumferential direction, a plurality of axial end portions AX are collectively sealed, and the resin sealing portion 41 is provided so as to form an annular shape along the axial end surface of the stator core 11. Therefore, the resin sealing portion 41 can be appropriately provided for a large number of axial end portions AX in the coil end portion CE2. Further, in the exposed portion 33 of the axial end portion AX that is the innermost in the radial direction and the exposed portion 33 of the axial end portion AX that is the outermost in the radial direction among the plurality of axial end portions AX arranged in the radial direction, the surfaces facing the respective side surfaces 41a, 41b (inner peripheral side surface and outer peripheral side surface) of the resin sealing portion 41 are inclined with respect to the axial direction in the same direction as those side surfaces 41a, 41b. Thereby, the thickness of the insulating resin up to the exposed portion 33 can be made uniform on the inner peripheral side and the outer peripheral side of the resin sealing portion 41. Therefore, even if a difference in thermal expansion occurs between the conductor and the insulating resin according to the difference in the linear expansion coefficient, the load acting on the exposed portion 33 can be equalized. Thereby, the stator winding 12 can be protected.

[0069] The welding portion W is provided in a range of 1 / 2 or more of the exposed portion 33 in the laser irradiation direction, and the non-welding portions UW of the respective exposed portions 33 are in contact with each other. Thereby, a highly reliable welding portion W can be formed.

[0070] Further, in the coil end portion CE2, in the configuration where each exposed portion 33 is sealed with an insulating resin, if the insulating resin enters between the two exposed portions 33 connected by welding, due to the difference in the linear expansion coefficient between the conductor and the insulating resin, there is a concern that shear may occur in the welding portion W between the exposed portions 33. In this regard, since the non-welding portions UW are in contact with each other between the two exposed portions 33 connected by welding, the shear of the welding portion due to the difference in the linear expansion coefficient between the conductor and the insulating resin can be suppressed.

[0071] In the welding process during the manufacture of the stator 10, laser irradiation is performed on the joint portion of the exposed portions 33 in a state where the exposed portions 33 are pressed against each other, such that the conductor width L1 on the laser irradiation side in the conductor joining direction is smaller than the conductor width L2 on the anti-irradiation side. Thereby, the stator 10 in which laser welding is appropriately performed can be manufactured.

[0072] In the inspection process after laser welding, by comparing the conductor width L1 on the laser irradiation side with the conductor width L2 on the anti-irradiation side, the inspection regarding laser welding can be appropriately performed, and thus the appearance of the welded portion W can be appropriately managed.

[0073] (Second Embodiment) The stator winding 12 in the second embodiment will be described. FIG. 12 is a perspective view of the stator 10 in the second embodiment, and FIG. 13 is a front view of the stator 10 in the second embodiment. In the second embodiment, the configuration of the conductor segment 30 is different from that in the first embodiment, and the description will focus on the differences from the configuration of the conductor segment 30 in the first embodiment shown in FIG. 5.

[0074] FIG. 14 is a perspective view showing a state where a plurality of conductor segments 30 are connected to each other. In the conductor segment 30, on the side of the anti-turn portion of the pair of straight portions 31, there is a connecting portion 30a extending in the circumferential direction, and an exposed portion 33 is provided on the connecting portion 30a. And in a state where the exposed portions 33 of different conductor segments 30 are joined to each other in the radial direction, these exposed portions 33 are connected by laser welding. That is, in the configuration of FIG. 14, different from the configuration of FIG. 5, the conductor segment 30 does not have a conductor tip portion 30b extending in the axial direction, and the exposed portions 33, which are the circumferential tip portions of the connecting portion 30a extending in the circumferential direction, are connected by welding. The coil end portion CE2 is configured by connecting the tip portion of a conductor (straight portion 31) extending in a certain direction in the circumferential direction and the tip portion of another conductor (straight portion 31) extending in a direction opposite to the certain direction in the circumferential direction.

[0075] In this embodiment, as shown in FIG. 15(a), at the exposed portion 33 of the conductor segment 30, the axially outer axially outer surface 33b, that is, the upper surface of the figure, in the axial direction is an arcuate surface that protrudes axially outward. Further, each surface of the exposed portion 33 other than the axially outer surface 33b, that is, the axially inner surface, the radially outer surface, and the radially inner surface, are all flat surfaces. Then, as shown in FIG. 15(b), the exposed portions 33 of the respective conductor segments 30 are overlapped in the radial direction and joined to each other, and are connected by laser welding in that state. In this case, the exposed portions 33 are joined to each other with their respective axially outer surfaces 33b being substantially flush, and laser welding is performed with the axially outer surface 33b (the upper surface of the figure) as the laser irradiation surface. Note that the portion where the exposed portions 33 face each other has a horizontally long shape where the circumferential direction is longer than the axial direction. During laser welding, laser scanning is performed within a predetermined range in the circumferential direction along the arcuate axially outer surface 33b.

[0076] At the joined portion of the exposed portions 33, by irradiating the laser from above the figure, a welded portion W is formed as shown in the figure by melting the conductor 34 in the exposed portion 33. In this case, as shown in FIG. 16 which is a cross-sectional view taken along line 16-16 of FIG. 15(b), the degree of melting of the conductor 34 is different between the laser irradiation side and the anti-irradiation side in the axial direction. That is, in the axial direction, on the laser irradiation side, the non-melting range in the conductor joining direction is small (that is, the melting range is large), and on the anti-irradiation side, the non-melting range in the conductor joining direction is large (that is, the melting range is small). As a result, the conductor width in the conductor joining direction is different in the axial direction, and the conductor width L11 on the laser irradiation side is smaller than the conductor width L12 on the anti-irradiation side (L11 < L12). In this configuration, the fact that the conductor width L11 on the laser irradiation side is smaller than the conductor width L12 on the anti-irradiation side means that melting at each exposed portion 33 has been appropriately performed, and according to this configuration, it is possible to confirm that appropriate laser welding has been performed. Further, at the joined boundary portion where the exposed portions 33 are joined, a raised portion 36 made of a molten conductor is formed on the laser irradiation side.

[0077] In the welding process of the conductor segment 30, laser welding is performed as follows. The welding process follows the procedure described in FIG. 11.

[0078] In a state where the exposed portions 33 are pressed against each other by a pair of pressing plates PL (see FIG. 11), laser irradiation is performed from the side opposite to the stator core 11 with respect to the joint surface between the exposed portions 33, thereby performing laser welding. At this time, in correlation with the depth of the laser welding, a difference in the melting amount occurs between the laser irradiation side and the anti-irradiation side on the joint surface, so that a change occurs in the conductor width of the exposed portions 33 according to the melting amount, and the conductor width L1 on the laser irradiation side becomes smaller than the conductor width L2 on the anti-irradiation side.

[0079] Here, in a configuration where the exposed portions 33 are respectively formed at the tip portions (circumferential direction tip portions) of the crossing portions 30a of the conductor segments 30 extending from opposite sides in the circumferential direction, and the circumferential direction tip portions are connected by laser welding, it is considered that it becomes even more difficult to confirm the welding depth compared to a configuration where the tip portions including the exposed portions 33 in each conductor segment 30 extend in the axial direction and the tip portions (axial direction tip portions) extending in the axial direction are connected by laser welding.

[0080] In this regard, in the present embodiment, the conductor width L1 on the laser irradiation side is smaller than the conductor width L2 on the anti-irradiation side, and from this configuration, it can be determined that the welding of the exposed portions 33 is properly performed, that is, the depth of the laser welding of the exposed portions 33 is a depth of a certain level or more, and the melting at each exposed portion 33 by the laser welding is properly performed.

[0081] (Modification example) In each of the above embodiments, a part of the configuration may be changed.

[0082] · The stationary winding 12 does not have to have a segment structure. In this case, in each phase winding provided for each phase of the stationary winding 12, a plurality of conductors are connected by laser welding. On the other hand, the conductor width in the joining direction of the exposed portions only needs to be smaller on the laser irradiation side, which is the side where the laser irradiation of each exposed portion is performed, than on the anti-irradiation side, which is the opposite side.

[0083] · In the above embodiment, the resin sealing portion 41 is provided at the coil end portion CE2 of the stationary winding 12, but a configuration in which the resin sealing portion 41 is not provided may also be used.

Explanation of reference numerals

[0084] 10... stator, 11... stator core, 12... stationary winding, 30... conductor segment, 33... exposed portion, 34... conductor, 35... insulating film, CE2... coil end portion.

Claims

1. comprising a stator core (11) and a stator winding (12) provided on the stator core; The stator winding is composed of a plurality of flat conductors (30) in which a conductor (34) is covered with an insulating film (35), and the conductors are provided in a state of being radially multi-layered and accommodated in slots of the stator core. An exposed portion (33) where the conductor is exposed is formed at the tip of the conductor. In the coil end portion (CE2) of the stator winding, the exposed portions of different conductors are connected by laser welding, and a plurality of axial end portions (AX) formed by connecting the exposed portions are arranged side by side in the radial direction and the circumferential direction. The conductor width in the joining direction of the exposed portions is smaller on the laser irradiation side, which is the side where the laser irradiation of each exposed portion is performed, than on the anti-irradiation side, which is the opposite side. A resin sealing portion (41) is provided by an insulating resin in a range including the exposed portion in the axial direction in the coil end portion. The resin sealing portion seals the plurality of axial end portions together and forms an annular shape extending along the axial end face of the stator core. The inner peripheral side surface on the radially inner side and the outer peripheral side surface on the radially outer side in the resin sealing portion are inclined with respect to the axial direction in a direction approaching each other on the outer side in the axial direction. In the exposed portion of the axial end portion that is the innermost in the radial direction and the exposed portion of the axial end portion that is the outermost in the radial direction among the plurality of axial end portions arranged in the radial direction, the surfaces facing the inner peripheral side surface and the outer peripheral side surface of the resin sealing portion are inclined with respect to the axial direction in the same direction as those inner peripheral side surface and outer peripheral side surface. A stator (10).

2. Between the two exposed portions connected by welding, there are a welded portion formed by a molten conductor and a non-welded portion where the non-molten conductors face each other, and the non-welded portions of the respective exposed portions are in contact with each other. The stator according to claim 1.

3. In the joint boundary portion where the exposed portions are joined, a raised portion (36) made of a molten conductor is formed on the laser irradiation side, the stator according to claim 1 or 2.

4. The coil end portion is configured by connecting a tip portion of the conductor extending in a certain circumferential direction on the outer side in the axial direction of the stator core and a tip portion of the other conductor extending in a direction opposite to the certain circumferential direction. The exposed portions are respectively formed at the tip portions of the conductors extending from opposite sides in the circumferential direction, and the exposed portions are connected by laser welding. The conductor width in the joining direction of the exposed portions is smaller on the laser irradiation side than on the anti-irradiation side. The stator according to any one of claims 1 to 3.

Images