Rotating electric machine stator

Abstract

To prevent adjacent stator coils from interfering with each other in a radial direction or a circumferential direction of the stator core.SOLUTION: A stator includes: a stator core 12 having a plurality of slots 18 and a plurality of teeth 16; and a stator coil 20 that is constituted by using a rectangular wire having a rectangular cross section and in which each slot insertion unit 22 inserted into different slots 18 separated in a circumferential direction of the stator core 12 is connected in the circumferential direction by a coil end unit 24 located outside the slot 18. The coil end portion 24 includes: two curved portions 24A that extend along the circumferential direction of the stator core 12 when viewed in a shaft direction of the stator core 12; and a crank portion 24B that is provided between the two curved portions 24A, connects both of them, and is bent in a crank shape so as to shift the two curved portions 24A in a radial direction of the stator core 12. Each curved portion 24A is bent at a bent portion B located on a center line L1 of the teeth 16 passing through a center of the stator core 12 as viewed in the shaft direction.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a stator for a rotating electrical machine, and more particularly to a stator having a stator coil made of rectangular wire having a rectangular cross section. [Background technology]

[0002] In recent years, rotating electric machines for vehicle drive have become increasingly smaller and more powerful, and some of them have stator windings made of stator coils made of rectangular wires with a rectangular cross section (see, for example, Patent Documents 1 and 2 listed below). The stator coils are configured such that slot insertion portions inserted into different circumferentially separated slots of the stator core are connected in the circumferential direction of the stator core by coil end portions located outside the slots. The coil end portions have two arc-shaped portions extending in the circumferential direction of the stator core when viewed in the axial direction of the stator core, and a crank portion provided between the two arc-shaped portions to connect them and bent in a crank shape so as to displace the two arc-shaped portions in the radial direction of the stator core. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6461158 [Patent Document 2] Patent No. 6638629 Summary of the Invention [Problem to be solved by the invention]

[0004] In each of the above prior arts, the coil end portion of the stator coil has two arc-shaped portions formed as arcs with a constant radius, and the four sides of the slot insertion portion with a rectangular cross section do not lie on a plane containing the central axis of the stator core and the central axis of the slot insertion portion, so the centers of curvature of the two arc-shaped portions do not coincide with the center of the stator core.

[0005] The misalignment of the centers of curvature described above manifests as interference between adjacent stator coils in the radial or circumferential direction. Measures to prevent this interference include providing clearance between the slot insertion portions, or ensuring a minimum spatial distance for insulation by adjusting the thickness of the insulation coating even if the stator coils interfere with each other. However, the former approach reduces the conductor space factor in the slot, reducing efficiency, while the latter approach requires optimizing the thickness of the insulation coating according to individual designs, taking into account the effect of stress on the insulation coating at the interference portion.

[0006] In consideration of the above, an object of the present invention is to provide a stator for a rotating electric machine that can prevent adjacent stator coils from interfering with each other in the radial or circumferential direction of the stator core. [Means for solving the problem]

[0007] The stator of a first aspect of a rotating electric machine comprises a stator core having a plurality of teeth and a plurality of slots, and a stator coil constructed using a flat wire with a rectangular cross section, in which slot insertion portions inserted into different slots spaced apart in the circumferential direction of the stator core are connected in the circumferential direction by coil end portions located outside the slots, and the coil end portions have two curved portions extending along the circumferential direction when viewed in the axial direction of the stator core, and a crank portion provided between the two curved portions to connect them and bent in a crank shape so as to shift the two curved portions radially of the stator core, and each of the curved portions is bent at a bending portion located on the center line of the tooth passing through the center of the stator core when viewed in the axial direction.

[0008] A first aspect of the stator for a rotating electric machine includes a stator core and a stator coil. The stator core has multiple slots and multiple teeth. The stator coil is constructed using a rectangular wire with a rectangular cross section. The slot insertion portions inserted into different circumferentially spaced slots of the stator core are connected in the circumferential direction by coil end portions located outside the slots. The coil end portions have two curved portions extending along the circumferential direction of the stator core when viewed in the axial direction of the stator core, and a crank portion provided between the two curved portions, connecting them and bending them in a crank shape so as to offset the two curved portions radially of the stator core. Each curved portion is bent at a bend located on the center line of a tooth passing through the center of the stator core when viewed in the axial direction of the stator core. This makes it possible to suppress the radial offset of each curved portion that would occur if each curved portion were an arc of a constant radius. As a result, it is possible to suppress interference between adjacent stator coils in the radial or circumferential direction of the stator core.

[0009] In the second aspect of the stator of a rotating electric machine, in the first aspect, each curved portion has a straight line, the portion between adjacent bent portions in the circumferential direction being perpendicular to the center line of the slot passing through the center of the stator core when viewed in the axial direction.

[0010] In the stator for a rotating electric machine according to the second aspect, the two curved portions of the coil end portion of the stator coil are arranged such that the portion between adjacent curved portions in the circumferential direction of the stator core is linear and perpendicular to the center line of the slot passing through the center of the stator core when viewed in the axial direction of the stator core, thereby forming a polygonal arc shape, and effectively suppressing deviation of the curved portions in the radial direction of the stator core.

[0011] The stator of the rotating electric machine of the third aspect is the same as that of the first aspect, in which each of the curved portions is bent in a convex shape that is similar in shape to the radially outward or radially inward when viewed in the axial direction, at the portion between adjacent bent portions in the circumferential direction.

[0012] In the stator of the third aspect of the rotating electric machine, the two curved portions of the coil end portion of the stator coil are bent in a similar convex shape toward the radially outer side or the radially inner side of the stator core when viewed in the axial direction of the stator core, at a portion between adjacent curved portions in the circumferential direction of the stator core. By making the curved shapes of the above-mentioned portions similar in each stator coil, interference due to misalignment of the curved portions in the radial direction of the stator core can be effectively suppressed.

[0013] A fourth aspect of the stator for a rotating electric machine is any one of the first to third aspects, wherein the circumferential center of the crank portion is located on the center line when viewed in the axial direction.

[0014] In the stator of the rotating electric machine of the fourth aspect, the crank portion provided at the coil end portion of each stator coil has a central portion in the circumferential direction of the stator core that is located on the center line of each tooth that passes through the center of the stator core when viewed in the axial direction of the stator core. In other words, the bent portion provided at each curved portion of the coil end portion and the central portion of the crank portion are both located on the center line. This fourth aspect also achieves the effects of the first aspect by incorporating the configuration of the first aspect. [Effects of the Invention]

[0015] As described above, in the stator of the rotary electric machine according to the present invention, it is possible to prevent adjacent stator coils from interfering with each other in the radial or circumferential direction of the stator core. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 2 is a perspective view showing a stator of the rotary electric machine according to the embodiment; [Figure 2] 2 is a perspective view showing a part of a stator coil and a stator core provided in the stator of the rotary electric machine according to the embodiment; FIG. [Figure 3] FIG. 3 is an enlarged perspective view of a portion of the configuration shown in FIG. 2. [Figure 4] 4 is a plan view showing the configuration shown in FIG. 3 as viewed in the axial direction of the stator core. FIG. [Figure 5] FIG. 2 is a plan view showing a stator coil and a part of a stator core as viewed in the axial direction of the stator core. [Figure 6] FIG. 2 is a plan view showing a part of the stator core and the outermost layer of the stator coil in the stator according to the embodiment. [Figure 7] 5 is a plan view corresponding to FIG. 4 for comparing the stator coil according to the embodiment with a conventional stator coil. FIG. [Figure 8] FIG. 4 is a perspective view corresponding to FIG. 3 and showing a part of a conventional stator coil and stator core. [Figure 9] 9 is a plan view showing the configuration shown in FIG. 8 as viewed in the axial direction of the stator core. [Figure 10] 8 is a plan view corresponding to FIG. 7, showing a part of the stator core and the stator coils in the outermost layer of a conventional stator. FIG. [Figure 11] 11 is a plan view corresponding to a part of FIG. 10, in which the stator coils of the outermost layer are shown only in outline form. [Figure 12] 7 is a plan view corresponding to a part of FIG. 6, in which the stator coils in the outermost layer are shown only in outline form. [Figure 13] FIG. 6 is a plan view corresponding to FIG. 5, showing a first modified example of the embodiment. [Figure 14] FIG. 8 is a plan view corresponding to FIG. 7, showing a first modified example of the embodiment. [Figure 15] FIG. 6 is a plan view corresponding to FIG. 5, showing a second modified example of the embodiment. [Figure 16] FIG. 8 is a plan view corresponding to FIG. 7, showing a second modified example of the embodiment. [Figure 17] FIG. 6 is a plan view corresponding to FIG. 5 and showing a third modified example of the embodiment. [Figure 18] FIG. 8 is a plan view corresponding to FIG. 7 and showing a third modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] A stator 10 (hereinafter simply referred to as "stator 10") for a rotating electric machine according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 18. Note that in each drawing, some reference numerals may be omitted to make the drawings easier to understand. As shown in FIG. 1, the stator 10 according to this embodiment includes a stator core 12 and a number of stator coils 20. This stator 10, together with a rotor (not shown), constitutes a three-phase AC rotating electric machine. Note that in FIG. 1, arrows Z, A, and D indicate the circumferential direction, axial direction, and radial direction of the stator core 12, respectively. Hereinafter, the circumferential direction of the stator core 12 may be simply referred to as the "circumferential direction," the axial direction of the stator core 12 may be simply referred to as the "axial direction," and the radial direction of the stator core 12 may be simply referred to as the "radial direction."

[0018] The stator core 12 is formed into a cylindrical shape by laminating a large number of electromagnetic steel sheets. The stator core 12 has a yoke 14, a large number of teeth 16, and a large number of slots 18. The large number of teeth 16 and the large number of slots 18 are formed on the inner periphery of the stator core 12, alternately arranged in the circumferential direction. The large number of slots 18 are open on both axial sides and radially inward.

[0019] 2, the stator coil 20 is, for example, a segment coil, formed by shaping a rectangular wire made of copper or the like into a substantially U-shape. The stator coil 20 has a pair of slot insertion portions 22 extending parallel to each other, a coil end portion 24 connecting one end of the pair of slot insertion portions 22, and a pair of lead portions 26 extending from the other end of the pair of slot insertion portions 22. The stator coil 20 is covered with an insulating coating except for the tip ends of the pair of lead portions 26.

[0020] A pair of slot insertion portions 22 are inserted from one axial side into different slots 18 that are spaced apart in the circumferential direction of the stator core 12. The coil end portions 24 are disposed outside the slots 18 on one axial side of the stator core 12, and connect one ends of the pair of slot insertion portions 22 to each other in the circumferential direction. As shown in FIG. 1 , a large number of stator coils 20 are stacked in multiple layers (three layers in this case) in the radial direction of the stator core 12 and aligned in an annular shape. A pair of lead portions 26 of each stator coil 20 protrudes from the end face on the other axial side of the stator core 12. These lead portions 26 are twisted and joined to the lead portions 26 of other stator coils 20.

[0021] As shown in FIG. 3, the coil end portion 24 of the stator coil 20 is formed in a substantially V- or U-shape when viewed in the radial direction. When viewed in the axial direction as shown in FIG. 4, the coil end portion 24 is curved in a bow shape along the circumferential direction. When viewed in the axial direction, the coil end portion 24 has two curved portions 24A extending along the circumferential direction, and a crank portion 24B provided between and connecting the two curved portions 24A. The crank portion 24B is bent in a crank shape so that the two curved portions 24A are offset from each other in the radial direction by approximately the thickness of the rectangular wire.

[0022] 1, the multiple stator coils 20 form one layer by sequentially inserting the slot insertion portions 22 into the slots 18 of the stator core 12, shifting the slots 18 one by one in the circumferential direction, to complete one turn. In this embodiment, three layers of stator coils 20 are formed. The circumferential length of the stator coils 20 for each layer varies slightly depending on the radial position of each layer.

[0023] As shown in FIG. 4, each of the two curved portions 24A of the coil end portion 24 is bent at a plurality of (here, three) bent portions B arranged at equal intervals in the circumferential direction. Each bent portion B is located on the center line L1 of each tooth 16 passing through the center of the stator core 12 when viewed in the axial direction. The bending angle θ (see FIG. 4) of each curved portion 24A at each bent portion B is set to "360 degrees divided by the number of slots 18." In each curved portion 24A, a region S (hereinafter referred to as "side portion S") between adjacent bent portions B in the circumferential direction forms a straight line perpendicular to the center line L1 when viewed in the axial direction. As a result, each curved portion 24A forms a polygonal arc shape. In the present embodiment, as an example, the circumferential center of the crank portion 24B is located on the center line L2 of the slot 18 passing through the center of the stator core 12 when viewed in the axial direction.

[0024] In this embodiment, the stator coil 20 is formed of a rectangular metal wire with a rectangular cross section. However, this is not a limitation. The stator coil may be formed of a rectangular metal wire with a rectangular cross section made up of multiple strands. In this embodiment, the lead portion 26 of one stator coil 20 is joined to the lead portion 26 of another stator coil 20. However, this is not a limitation. The stator coil may be electrically joined to another stator coil within a slot in the stator core. Alternatively, the stator coil may be a so-called wave winding coil wound continuously around the entire circumference of the stator core. In this embodiment, the stator core 12 is formed of laminated steel plates. However, this is not a limitation. The stator core may be formed, at least in part, of a powder magnetic core.

[0025] (Action and effect) This embodiment includes a stator core 12 and a stator coil 20. The stator core 12 has a plurality of slots 18 and a plurality of teeth 16. The stator coil 20 is formed using a flat wire with a rectangular cross section, and slot insertion portions 22 inserted into different slots 18 spaced apart in the circumferential direction of the stator core 12 are connected in the circumferential direction of the stator core 12 by coil end portions 24 located outside the slots 18. The coil end portions 24 have two curved portions 24A extending along the circumferential direction of the stator core 12 when viewed in the axial direction of the stator core 12, and a crank portion 24B provided between the two curved portions 24A to connect them and bent in a crank shape so as to displace the two curved portions 24A in the radial direction of the stator core 12.

[0026] Each curved portion 24A is bent at a bend B located on the center line L1 of each tooth 16 passing through the center of the stator core 12 when viewed in the axial direction of the stator core 12. Furthermore, each curved portion 24A has a side S between adjacent bends B in the circumferential direction of the stator core 12 that is linear and perpendicular to the center line L2 of each slot 18 passing through the center of the stator core 12 when viewed in the axial direction of the stator core 12. This allows each curved portion 24A to have a polygonal arc shape, effectively preventing the radial misalignment of each curved portion 24A (see the two-dot chain line in FIG. 7 ) that would occur if each curved portion were an arc with a constant radius. As a result, it is possible to prevent adjacent stator coils 20 from interfering with each other in the radial or circumferential direction of the stator core 12. This facilitates the manufacture of the stator 10, improves the space factor of the stator coil 20, and makes it easier to ensure the insulation of the stator coil 20 and the axial positional accuracy of the coil end portions 24.

[0027] The above-mentioned effects will be further explained using a comparative example shown in Figs. 8 to 10. This comparative example has the same configuration as the present embodiment, except that the two arc-shaped portions 24A of the stator coil 20 are formed into arcs with a constant radius. In this comparative example, as shown in Fig. 9, in the stator coil 20, the four sides S1, S2, S3, and S4 of the slot insertion portion 22, which has a rectangular cross section, do not lie on a plane P that includes the central axis of the stator core 12 and the central axis of the slot insertion portion 22. Therefore, in this comparative example, the centers of curvature of the two arc-shaped portions 24A do not coincide with the center of the stator core 12.

[0028] As shown in Fig. 11, the mismatch in the centers of curvature manifests as interference between circumferentially or radially adjacent stator coils 20. Note that Fig. 11 is a plan view corresponding to a portion of Fig. 10, which shows only the outline of the outermost layer stator coil 20. To prevent this interference, various measures have been taken, such as providing clearance between radially adjacent slot insertion portions 22, or ensuring a minimum spatial distance for insulation by adjusting the thickness of the insulating coating even if the stator coils 20 interfere with each other. However, the former approach reduces the conductor space factor in the slot, reducing efficiency, while the latter approach poses the problem of needing to optimize the thickness of the insulating coating according to individual designs, taking into account the effect of stress on the insulating coating at the interference portion.

[0029] The mismatch in the centers of curvature also manifests as internal stress when the stator coil 20 is manufactured using a rectangular wire made up of multiple strands. As a result of this internal stress being alleviated, problems arise such as the arc-shaped portions 24A not forming a circular arc, or the strands becoming twisted and damaging the insulating coating.

[0030] In contrast, in this embodiment, as shown in Fig. 12, each curved portion 24A of the coil end portion 24 has a polygonal arc shape, which makes it possible to effectively suppress radial displacement of each curved portion 24A. As a result, it is possible to suppress interference between adjacent stator coils 20 in the radial or circumferential direction of the stator core 12. Furthermore, even when the stator coil 20 is manufactured using a flat wire having a rectangular cross section made up of multiple strands, it is possible to suppress the occurrence of internal stress.

[0031] In the above embodiment, the circumferential center of the crank portion 24B provided in the coil end portion 24 is located on the center line L2 of the slot 18 passing through the center of the stator core 12 when viewed in the axial direction. However, this is not limited to this, and a configuration such as the first modified example shown in FIGS. 13 and 14 may also be used. In this first modified example, the circumferential center of the crank portion 24B is located on the center line L1 of the tooth 16 passing through the center of the stator core 12 when viewed in the axial direction. In this first modified example, the configuration other than the above is the same as in the above embodiment. In this first modified example, basically the same actions and effects as in the above embodiment are achieved.

[0032] In the above embodiment, the side S of each curved portion 24A of the coil end portion 24 is linear and perpendicular to the center line L1 of the tooth 16 passing through the center of the stator core 12 when viewed in the axial direction. However, this is not limited to this, and a configuration such as a second modified example shown in Figures 15 and 16 may be used. In this second modified example, the side S of each curved portion 24A of the coil end portion 24 is curved in an arc shape that convexly extends radially outward when viewed in the axial direction. Note that the side S of each curved portion 24A may also be curved in an arc shape that convexly extends radially inward when viewed in the axial direction.

[0033] In this second modified example, when a polygonal arc shape is drawn by connecting the centers of the bent portions B and the centers of the slot insertion portions 22 with imaginary straight lines (see two-dot chain lines V1, V2, and V3 in FIG. 15 ), the position of each bent portion B is set so that the smaller of the angles formed by these straight lines is 360 degrees divided by the number of slots 18. In this second modified example, the configuration other than the above is the same as in the above embodiment. In this second modified example, by similarly matching the bending shape of each side portion S in each stator coil 20, radial deviation of each curved portion 24A can be effectively suppressed, and basically the same actions and effects as in the above embodiment can be achieved.

[0034] Furthermore, in the second modified example described above, the circumferential center of the crank portion 24B provided in the coil end portion 24 is located on the center line L2 of the slot 18 that passes through the center of the stator core 12 when viewed in the axial direction, but this is not limiting and a configuration like the third modified example shown in Figures 17 and 18 may also be used. In this third modified example, as in the first modified example, the circumferential center of the crank portion 24B is located on the center line L1 of the tooth 16 that passes through the center of the stator core 12 when viewed in the axial direction. In this third modified example, too, basically the same actions and effects as in the above embodiment are achieved.

[0035] In addition, the present invention can be implemented with various modifications within the scope of the gist thereof. Furthermore, it goes without saying that the scope of the rights of the present invention is not limited to the above-described embodiment and each of the modifications. [Explanation of symbols]

[0036] 10 Stator 12 Stator core 16 Teeth 18 slots 20 stator coil 22 Slot insertion part 24 Coil end 24A curved section 24B crank section B Bending section L1: The center line of the teeth that passes through the center of the stator core when viewed in the axial direction of the stator core L2: The centerline of the slot that passes through the center of the stator core when viewed in the axial direction of the stator core S-side section (the section between adjacent bent sections in the circumferential direction of the stator core)

Claims

1. a stator core having a plurality of teeth and a plurality of slots; a stator coil formed using a rectangular wire having a rectangular cross section, the stator coil having slot insertion portions inserted into different slots spaced apart in the circumferential direction of the stator core and connected in the circumferential direction by coil end portions located outside the slots; Equipped with The coil end portion is two curved portions extending across at least two or more of the teeth along the circumferential direction when viewed in the axial direction of the stator core; a crank portion provided between the two curved portions to connect them and bent in a crank shape so as to displace the two curved portions in the radial direction of the stator core, Each of the curved portions is bent at a bending portion located on a center line of the tooth passing through a center of the stator core as viewed in the axial direction, the bent portion is provided for each of the teeth that the curved portion spans, A stator for a rotating electric machine in which each curved portion has a polygonal arc shape, or the portion between adjacent bent portions in the circumferential direction is bent in an arc shape that convex outward in the radial direction when viewed in the axial direction.

2. A stator for a rotating electric machine as described in Claim 1, wherein the circumferential central portion of the crank portion is located on the center line of the teeth when viewed in the axial direction.

Images