Stator of rotary electric machine

Abstract

To achieve approximately uniform rigidity and magnetic resistance of a stator core in a circumferential direction.SOLUTION: In a stator core (11q), abutting portions (11a) of end surfaces (11e) in a circumferential direction of stacked "C" shaped steel plates are bonded on an outer circumferential side. The abutting portion is provided at a portion between teeth (22) adjacent to each other in a back yoke (21). A bonded portion (11m) in the abutting portion has a length less than or equal to 50% of a length of the whole abutting portion in a radial direction of the stator core. The back yoke has formed therein at least one slit (25) extending with a length more than or equal to 50% of a length of the whole back yoke in the radial direction of the stator core.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a stator for a rotating electrical machine. [Background technology]

[0002] For example, there is a stator core that is made by stacking a predetermined number of rectangular plate-shaped magnetic members, each having trapezoidal slots that widen toward the opening and are formed at a predetermined pitch, and then laser welding the outer periphery to create a rectangular parallelepiped base core.A winding assembly is inserted into the base core, and the base core is rolled into a cylindrical shape, and the end faces are abutted and welded together (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3310971 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when joining the abutting portions of the end faces of the elemental iron cores, the abutting portions are joined from either the outer or inner circumferential side of the elemental iron cores. In this case, the proportion of the joined portion of the abutting portion in the radial direction of the elemental iron core is often 50% or less of the entire abutting portion. At the abutting portion, only the joined portion essentially functions as a core, and the unjoined portion essentially does not function as a core. Therefore, at the abutting portion of the end faces, the radial thickness of the stator core is essentially thinner than other portions, which may result in non-uniform rigidity and magnetic resistance of the stator core in the circumferential direction.

[0005] The present invention has been made to solve the above-mentioned problems, and its main purpose is to make the rigidity and magnetic resistance of a stator core nearly uniform in the circumferential direction in a stator core in which the outer or inner sides of the abutting portions between the circumferential end faces of stacked ``C''-shaped steel plates are joined. [Means for solving the problem]

[0006] The first means for solving the above problem is: A stator (10) for a rotating electric machine includes a stator core (11) formed by joining an outer circumferential side or an inner circumferential side of abutting portions (11a) between circumferential end faces (11e) of stacked C-shaped steel plates (20), and a stator winding (12) inserted into a plurality of slots (23) formed in the stator core, The stator core includes a back yoke (21) extending in a circumferential direction around a central axis of the stator core, and a plurality of teeth (22) extending from the back yoke toward the central axis, and the slots are formed between adjacent teeth, the abutment portion is provided in a portion of the back yoke between adjacent teeth, In the radial direction of the stator core, the length of the joined portion (11 m) of the contact portion is 50% or less of the entire length of the contact portion, The back yoke is formed with at least one slit (25) extending in the radial direction of the stator core over a length that is 50% or more of the entire length of the back yoke.

[0007] According to the above configuration, in the stator core, the outer or inner circumferential sides of the abutment portions between the circumferential end faces of the stacked "C"-shaped steel plates are joined. When manufacturing such a stator core, the abutment portions are joined on the outer or inner circumferential sides of the stator core. In addition, in the radial direction of the stator core, the length of the joined portion of the abutment portion is 50% or less of the entire length of the abutment portion. Here, in the abutment portion, only the joined portion essentially functions as a core, and the unjoined portion essentially does not function as a core. Therefore, the radial thickness of the back yoke at the abutment portion is essentially 50% or less of the entire radial thickness of the back yoke, which may result in non-uniform rigidity and magnetic resistance of the stator core in the circumferential direction.

[0008] In this regard, the back yoke has at least one slit formed in the radial direction of the stator core, the slit extending over a length equal to or greater than 50% of the entire length of the back yoke. At circumferential positions where the slit is formed in the back yoke, only the portion where the slit is not formed essentially functions as a core, and the portion where the slit is formed does not essentially function as a core. Therefore, the radial thickness of the back yoke at the circumferential position where the slit is formed is substantially 50% or less of the entire radial thickness of the back yoke. Therefore, the rigidity and magnetic resistance of the stator core at the circumferential position where the slit is formed can be made closer to the rigidity and magnetic resistance of the stator core at the abutment portion. Therefore, the rigidity and magnetic resistance of the stator core can be made closer to uniformity in the circumferential direction. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. 10 is a schematic diagram showing a conventional bare iron core after bending deformation. [Figure 5] 10 is a graph showing the relationship between the phase and stiffness of a conventional stator core. [Figure 6] 10 is a schematic diagram showing a state in which the roundness of a conventional core is reduced after bending deformation. [Figure 7] 10 is a graph showing the relationship between the phase and magnetic resistance of a conventional stator core. [Figure 8] An enlarged view of a rectangular steel plate. [Figure 9] FIG. [Figure 10] 4 is a graph showing the relationship between the phase and stiffness of a stator core. [Figure 11] FIG. [Figure 12] 4 is a graph showing the relationship between the phase of a stator core and magnetic resistance. [Figure 13]FIG. 10 is a perspective view showing a manner in which a plurality of conductor segments are inserted into a stator core. [Figure 14] FIG. [Figure 15] A close-up of a portion of the steel plate in a bent state. [Figure 16] 1 is a graph showing the relationship between residual stress and iron loss. [Figure 17] FIG. 10 is a partially enlarged view showing an example of a modified steel plate. [Figure 18] FIG. 10 is a partially enlarged view showing another modified example of the steel plate. [Figure 19] FIG. 10 is a partially enlarged view showing another modified example of the steel plate. [Figure 20] FIG. 10 is a partially enlarged view showing another modified example of the steel plate. [Figure 21] FIG. 10 is a partially enlarged view showing another modified example of the steel plate. [Figure 22] FIG. 10 is a partially enlarged view showing another modified example of the steel plate. [Figure 23] FIG. 10 is a schematic diagram showing a modified example of the stator core. [Figure 24] FIG. 10 is a partially enlarged view showing a modified example of the slit. [Figure 25] FIG. 10 is a partially enlarged view showing another modified example of the slit. [Figure 26] 10A and 10B are schematic diagrams showing examples of modifications to the bare iron core after bending deformation. [Figure 27] FIG. 10 is an enlarged partial view showing the neutral line during bending deformation. [Figure 28] FIG. 10 is an enlarged partial view showing the neutral line after bending deformation. [Figure 29] FIG. 10 is a schematic diagram showing a buckling portion after bending deformation. [Figure 30] FIG. [Figure 31] FIG. 10 is a partially enlarged view showing a modified example of the recessed portion. [Figure 32] FIG. 10 is a partially enlarged cross-sectional view showing a modified example of the recessed portion. [Figure 33] FIG. [Figure 34] FIG. [Figure 35] FIG. [Figure 36] FIG. 10 is a schematic diagram showing a modified example of the bare iron core. [Figure 37] FIG. [Figure 38] FIG. 4 is a schematic diagram showing how a winding assembly is inserted into a slot of an iron core. [Figure 39] FIG. 4 is a schematic diagram showing an elemental iron core after bending deformation. [Figure 40] FIG. 10 is a schematic diagram showing another modified example of the stator core. [Figure 41] FIG. 10 is a schematic diagram showing another modified example of the stator core. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment embodied in a stator of a rotating electric machine mounted on a vehicle (for example, a hybrid vehicle or an electric vehicle) will be described below with reference to the drawings. In the following embodiments and modifications, identical or equivalent parts are designated by the same reference numerals in the drawings, and the same explanations are incorporated herein for the parts with the same reference numerals. The rotating electric machine is, for example, an electric motor (motor), a generator, or an MG (Motor Generator).

[0011] The rotating electric machine of this embodiment is applicable to permanent magnet synchronous motors, wound field motors, and induction motors, and is a rotating electric machine with multiple phase windings. The rotating electric machine includes a cylindrical stator 10 (shown in FIG. 1 ), a rotor (not shown) disposed radially inside the stator 10, and the like. The rotor is disposed rotatably about a rotation axis (central axis) relative to the stator 10. Hereinafter, the term "axial direction" refers to the axial direction of the stator 10, i.e., the axial direction of the rotor's rotation axis; the term "radial direction" refers to the radial direction of the stator 10, i.e., the direction passing through the center of the rotor's rotation axis and perpendicular to the rotation axis; and the term "circumferential direction" refers to the circumferential direction of the stator 10, i.e., the direction around the rotor's rotation axis.

[0012] As shown in FIGS. 1 and 2 , the stator 10 includes a cylindrical (annular) stator core 11 and a stator winding 12 wound around the stator core 11. The rotating electric machine of this embodiment is an inner rotor type rotating electric machine, in which a rotor is rotatably disposed radially inside the stator 10. In this embodiment, 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. A power line bus bar 13 is connected to one end of each phase winding, and a neutral line bus bar 14 is connected to the other end. In the stator winding 12, the area that overlaps with the stator core 11 in the axial direction is an in-slot coil portion CS, and the portions axially outward of the stator core 11 on both axial sides are coil end portions CE1 and CE2.

[0013] The case 15 is shrink-fitted or press-fitted onto the outer periphery of the stator core 11. More specifically, the case 15 (housing) is made of metal and has a cylindrical shape. The case 15 is heated and expanded, and the stator core 11, whose outer diameter at room temperature is slightly larger than the inner diameter of the case 15, is fitted into the case 15, and then cooled to fix the two together. The case 15 is formed with an escape groove or the like to allow the power bus bar 13 to escape. Alternatively, the power bus bar 13 can be positioned so that it does not interfere with the case 15.

[0014] The stator core 11 is formed by rolling an element core 11p shown in Fig. 3 into a cylindrical shape. The element core 11p is formed by stacking a predetermined number of rectangular steel plates 20 (magnetic members) in which slots 23 are formed at a predetermined pitch. The slots 23 are formed between adjacent teeth 22. The stacked steel plates 20 are joined together to form the element core 11p in a rectangular parallelepiped shape.

[0015] 4 is a schematic diagram showing a conventional elemental iron core 11q after bending deformation. The elemental iron core 11q is formed by rolling (bending) the elemental iron core 11p into a cylindrical shape. More specifically, the elemental iron core 11q is formed by rolling the elemental iron core 11p into a "C" shape and joining, for example welding, the outer peripheries of the abutting portions 11a between the circumferential end faces 11e. A welded portion 11m (joint portion) is formed on the outer periphery of the abutting portion 11a (0° position).

[0016] In the radial direction of the raw iron core 11q, the proportion of the welded portion 11m in the contact portion 11a is 50% or less, for example 25%, of the entire contact portion 11a. Therefore, as shown in FIG. 5, in the core formed by the raw iron core 11q, the rigidity of the contact portion 11a (0° position) is significantly lower than the rigidity of other portions. In other words, the rigidity of the stator core 11 becomes uneven in the circumferential direction. Therefore, the raw iron core 11q is deformed as shown in FIG. 6 due to a repulsive force that tries to return it to its original rectangular parallelepiped shape. As a result, the roundness of the raw iron core 11q decreases.

[0017] Furthermore, at the abutting portion 11a, only the welded portion 11m essentially functions as a core, and the unwelded portion (the portion of the end face 11e that is only abutting) does not essentially function as a core. Therefore, at the abutting portion 11a where the end faces 11e are abutted, the radial thickness of the stator core 11 is substantially thinner than other portions. Therefore, as shown in FIG. 7, in the core formed by the bare iron core 11q, the magnetic resistance at the abutting portion 11a (0° position) is significantly higher than the magnetic resistance of other portions. In other words, the magnetic resistance of the stator core 11 becomes non-uniform in the circumferential direction.

[0018] Therefore, in this embodiment, the steel plates 20 that make up the element core 11p are formed as shown in Fig. 8. Note that the same parts as those in the prior art are given the same reference numerals and the description thereof will be incorporated herein.

[0019] The steel plate 20 (magnetic member) is formed in a rectangular plate shape. The back yoke forming portion 21a of the steel plate 20 is a portion that forms the back yoke 21 of the stator core 11 after the steel plate 20 is laminated and bent. In the back yoke forming portion 21a of the steel plate 20, one slit 25 is formed at each position corresponding to the plurality of slots 23, so that the slit 25 opens toward the slot 23. That is, the plurality of slits 25 are formed side by side in the longitudinal direction (the circumferential direction after bending) in the back yoke forming portion 21a. The slits 25 extend in the outer radial direction with a width narrower than the width of the slots 23 in the circumferential direction. The slits 25 are formed in a V-shape in the back yoke forming portion 21a that widens from a predetermined position in the radial direction of the stator core 11 toward the inner radial direction. In the short-side direction (width direction) of the rectangular steel plate 20, the slits 25 extend a length that is 50% or more of the entire length of the back yoke forming portion 21a. Opposing side surfaces 25a of the slits 25 (hereinafter also referred to as "slit mating surfaces 25a") are formed flat. A predetermined number of steel plates 20 of the same shape are stacked and the stacked steel plates 20 are joined together, for example, by welding, to form the rectangular parallelepiped element core 11p shown in Figure 3.

[0020] When bending the rectangular parallelepiped element core 11p into a cylindrical shape, the element core 11p is deformed so that the slit mating surfaces 25a approach each other. The slit mating surfaces 25a are then brought into contact with or close to each other. By rolling (bending) the element core 11p into a cylindrical shape, an element core 11q similar to that shown in FIG. 4 is formed.

[0021] FIG. 9 is a partially enlarged view showing a welded portion 11m of an element core 11q of this embodiment. The stator core 11 has an annular back yoke 21. The back yoke 21 extends in the circumferential direction about a central axis C1 (not shown). The stator core 11 has a plurality of teeth 22 that protrude radially inward (toward the central axis C1) from the back yoke 21 and are arranged at predetermined distances in the circumferential direction. In the radial direction of the stator core 11, the length of the back yoke 21 is 70% or more, for example, 75 to 85%, of the length of the teeth 22. Slots 23 are formed between adjacent teeth 22. The slots 23 have an opening shape that extends radially and are arranged at equal intervals in the circumferential direction of the stator core 11. The number of slots 23 in the stator core 11 is, for example, 48. The slots 23 open to the inner circumferential side of the stator core 11.

[0022] The elemental iron core 11q is formed by rolling the elemental iron core 11p into a "C" shape and joining, for example welding, the outer periphery sides of the abutment portions 11a between the circumferential end faces 11e of the elemental iron core 11p. The abutment portions 11a are provided between adjacent teeth 22 on the back yoke 21. That is, the abutment portions 11a are provided in the circumferential direction of the back yoke 21 (elemental iron core 11q) at positions corresponding to the slots 23, not at positions corresponding to the teeth 22. The abutment portions 11a are welded from the outer periphery side of the elemental iron core 11q. A welded portion 11m (joint) is formed on the outer periphery side of the abutment portion 11a (0° position). In the radial direction of the elemental iron core 11q (stator core 11), the length of the welded portion of the abutment portion 11a (welded portion 11m) is 50% or less, for example 20 to 40%, of the entire length of the abutment portion 11a.

[0023] The element core 11q is formed with a series of axially overlapping slits 25 corresponding to each slot 23. As a result, the element core 11q has 48 slits 25 formed at equal intervals in the circumferential direction. That is, the back yoke 21 has at least one slit 25 extending in the radial direction of the element core 11q. The slit 25 extends in the radial direction of the element core 11q by 50% or more, for example, 60 to 80%, of the overall length of the back yoke 21. That is, the length of the slit 25 in the radial direction of the element core 11q corresponds to the length of the unwelded portion (portion that is only in contact) of the contact portion 11a in the radial direction of the element core 11q. As a result, the rigidity of the portion of the back yoke 21 where the slit 25 is formed is made closer to the rigidity of the contact portion 11a.

[0024] As shown in FIG. 10, in the core formed by the base iron core 11q, the rigidity of the portion where the slits 25 are formed is close to the rigidity of the abutment portion 11a (0° position). In other words, the rigidity of the stator core 11 is nearly uniform in the circumferential direction. Therefore, even if a repulsive force occurs in the base iron core 11q that tries to return it to its original rectangular parallelepiped shape, a decrease in the circularity of the stator core 11 is suppressed. As a result, the cylindrical shape of the stator core 11 is maintained, as shown in FIG. 11.

[0025] Furthermore, at the abutting portion 11a, only the welded portion 11m essentially functions as a core, and the unwelded portion (the portion of the end face 11e that is only abutting) does not essentially function as a core (its function as a core is reduced). Similarly, at the position corresponding to the slit 25 in the circumferential direction of the back yoke 21, only the portion without the slit essentially functions as a core, and the portion with the slit 25 does not essentially function as a core (its function as a core is reduced). At the abutting portion 11a between the end faces 11e, the radial thickness of the stator core 11 is substantially thinner than other portions. Similarly, at the position corresponding to the slit 25 in the circumferential direction of the back yoke 21, the radial thickness of the stator core 11 is substantially thinner than other portions. Therefore, as shown in FIG. 12, in the core formed by the bare iron core 11q, the difference between the magnetic resistance at the abutting portion 11a (0° position) and the magnetic resistance of other portions is reduced. That is, the magnetic resistance of the stator core 11 becomes nearly uniform in the circumferential direction.

[0026] 13 is a perspective view showing how multiple conductor segments 30 are inserted into the stator core 11. The multiple conductor segments 30 are arranged in a predetermined order and inserted vertically along the central axis C1 of the stator core 11 into the corresponding slots 23, respectively.

[0027] The stator winding 12 is configured by connecting multiple phase windings in a Y connection (star connection), a Δ connection, or a Y-Δ connection. The stator winding 12 is configured by connecting multiple conductor segments 30, which are divided conductors formed into a roughly U-shape from an electrical conductor of a uniform thickness with a roughly rectangular cross section (flat square cross section). The stator winding 12 is distributedly wound around the teeth 22.

[0028] More specifically, multiple conductor segments 30 are inserted into the slots 23 of the stator core 11 in a radially aligned state. In this embodiment, the slots 23 are configured to accommodate the linear portions 31 of the conductor segments 30 stacked in four layers (multiple layers). In the conductor segment 30, a pair of linear portions 31 is accommodated in two slots 23 that are spaced apart by two or more slots (separated by a predetermined coil pitch). Two slots 23 that are spaced apart by two or more slots do not refer to two adjacent slots 23, but rather to two slots 23 with one or more slots 23 sandwiched between them. The two slots 23 that are spaced apart by two or more slots to accommodate a pair of linear portions 31 may be, for example, two slots 23 that are spaced apart by three to six slots (every four to seven slots). The pair of linear portions 31 of the conductor segment 30 are accommodated in the two slots 23 with their radial positions shifted by one. For example, when one straight section 31 is accommodated in the nth position from the radially inner side (the back yoke 21 side), the other straight section 31 is accommodated in the n+1th or nth position from the radially inner side.

[0029] In this way, the stator 10 shown in Fig. 1 is configured. The stator winding 12 generates magnetic flux when a current (alternating current) is supplied from a power source via an inverter (not shown).

[0030] The present embodiment described above in detail has the following advantages.

[0031] At least one slit 25 is formed in the back yoke 21 in the radial direction of the stator core 11, extending a length equal to or greater than 50% of the overall length of the back yoke 21. At circumferential positions of the back yoke 21 where the slit 25 is formed, only the portions where the slit 25 is not formed essentially function as cores, and the portions where the slit 25 is formed do not essentially function as cores. Therefore, the radial thickness of the back yoke 21 at the circumferential positions where the slit 25 is formed is substantially 50% or less of the overall radial thickness of the back yoke 21. Therefore, the rigidity and magnetic resistance of the stator core 11 at the circumferential positions where the slit 25 is formed can be made closer to the rigidity and magnetic resistance of the stator core 11 at the abutment portion 11a. This makes it possible to make the rigidity and magnetic resistance of the stator core 11 more uniform in the circumferential direction.

[0032] In high-power density rotating electric machines, the length of the back yoke 21 in the radial direction of the stator core 11 is often 70% or more of the length of the teeth 22. In such a configuration, the length of the joined portion (welded portion 11m) of the contact portion 11a in the radial direction of the stator core 11 is likely to be particularly short compared to the entire length of the contact portion 11a. This makes it easy for the rigidity and magnetic resistance of the stator core 11 to become non-uniform in the circumferential direction, which can reduce the roundness of the stator core 11 and deteriorate the NV (Noise Vibration) characteristics of the rotating electric machine. Since the rigidity and magnetic resistance can be made nearly uniform in the circumferential direction of such a stator core 11, it is more effective in improving the roundness of the stator core 11 and improving the NV characteristics of the rotating electric machine.

[0033] The stator winding 12 is wound in a distributed manner around the teeth 22. With this configuration, the stator winding 12 is wound around a plurality of teeth 22, which has the effect of making the rigidity of the stator core 11 uniform. Therefore, the rigidity of the stator core 11 can be made more uniform in the circumferential direction.

[0034] A cylindrical case 15 is fitted to the outer periphery of the stator core 11. With this configuration, if the stator core 11 does not have a high degree of circularity, it becomes difficult to fit the cylindrical case 15 to the outer periphery of the stator core 11. However, since the rigidity of this stator core 11 can be made nearly uniform in the circumferential direction, the circularity of the stator core 11 can be improved. As a result, it becomes easier to fit the cylindrical case 15 to the outer periphery of the stator core 11.

[0035] Because the outer periphery of the contact portion 11a is joined, an unjoined portion is formed on the inner periphery of the contact portion 11a. In the back yoke 21, the slits 25 open on the inner periphery. Therefore, the unjoined portion of the contact portion 11a and the slits 25 both open on the inner periphery. Therefore, the rigidity and magnetic resistance of the stator core 11 at the circumferential position where the slits 25 are formed can be made even closer to the rigidity and magnetic resistance of the stator core 11 at the contact portion 11a. Therefore, the rigidity and magnetic resistance of the stator core 11 can be made even more uniform in the circumferential direction.

[0036] The above embodiment can be modified as follows: The same parts as those in the above embodiment are denoted by the same reference numerals and the description thereof will be incorporated herein.

[0037] 14, a circular hole 25b (hole) may be formed at the end (base) of the slit 25 on the opposite side (outer diameter side) from the slot 23. With this configuration, when bending a rectangular steel plate 20 (a rectangular parallelepiped element core 11p) into an annular (cylindrical) shape, the steel plate 20 can be deformed so that the slit mating surfaces 25a approach each other, using the circular hole 25b as a fulcrum. Therefore, workability can be further improved when bending the steel plate 20 into an annular shape.

[0038] 15 is a partially enlarged view of the steel plate 20 in a bent state. The dashed-dotted lines schematically show the positions where stress remains, and the residual stress at the position corresponding to point P is greater than in other parts. Because the stator core 11 is formed in the shape of a polygonal pillar, the residual stress due to the tensile deformation of the steel plate 20 is concentrated at the corners (outer edge portions 26) of the stator core 11.

[0039] FIG. 16 is a graph showing the relationship between residual stress and iron loss. As shown in the graph, the iron loss increases as the residual tensile stress increases. When rectangular steel plate 20 (rectangular solid-shaped element iron core 11p) is bent into an annular (cylindrical) shape, the tensile stress at outer edge 26 of stator core 11 increases, as indicated by arrow A1. As a result, iron loss increases to L1. Thereafter, case 15 is shrink-fitted onto the outer periphery of stator core 11, and the tensile stress decreases due to the compressive load, as indicated by arrow A2. As a result, iron loss decreases to L2.

[0040] As shown in Fig. 17(a), a recess 25c may be formed on one of the opposing side surfaces 25a (slit mating surfaces 25a) of the slit 25, and a protrusion 25d may be formed on the other. As shown in Fig. 17(b), the recess 25c and the protrusion 25d may be press-fitted together. With this configuration, the recess 25c and the protrusion 25d formed on the slit mating surfaces 25a and press-fitted together can prevent the slit mating surfaces 25a from separating.

[0041] As shown in Fig. 18(a), an acute-angled notch 25e (first engagement portion) may be formed on one of the opposing side surfaces 25a (slit mating surfaces 25a) of the slit 25, and a protrusion 25f (second engagement portion) having an R portion (rounded portion) may be formed on the other. As shown in Fig. 18(b), the notch 25e and the protrusion 25f may be fitted (engaged). With this configuration, the notch 25e and the protrusion 25f formed in and fitted to the slit mating surface 25a can prevent the slit mating surfaces 25a from separating.

[0042] As shown in Fig. 19, a notch 27 may be formed in the outer edge 20a of the steel sheet 20 corresponding to the end (circular hole 25b) of the slit 25 opposite the slot 23. The notch 27 is formed in a V-shape or a U-shape. With this configuration, it is possible to reduce the portion (outer edge 20a) where stress remains when the rectangular steel sheet 20 is deformed into an annular shape, and therefore the amount of springback can be reduced.

[0043] 20 , the end (circular hole 25b) of each slit 25 opposite the slot 23 may be located in the radially outer direction of the tooth 22, as indicated by the dashed arrow. That is, the end of each slit 25 opposite the slot 23 may be offset from the radially outer direction of the slot 23. The end (opening) of each slit 25 on the same side as the slot 23 is located in the radially outer direction of the slot 23. With this configuration, when the magnetic flux flowing in the circumferential direction of the back yoke 21 is blocked by the notch 27 or the circular hole 25b formed in the outer edge portion 20a of the rectangular steel plate 20, the magnetic flux can be diverted to the portion of the back yoke 21 in the radially outer direction of the tooth 22 and flow in the circumferential direction. Therefore, deterioration of the magnetic characteristics of the stator core 11 due to magnetic saturation can be suppressed.

[0044] As shown in FIG. 21 , the opposing side surfaces 25a of the slit 25 may be formed in an arc-like shape. In this case, the opposing side surfaces 25a have the same radius of curvature. With this configuration, when the rectangular steel plate 20 is deformed into an annular shape, the slit mating surfaces 25a are easily deformed so that the curvature of the arc-shaped slit mating surfaces 25a changes, which makes it easier to absorb any shape differences in the slit mating surfaces 25a due to manufacturing errors or the like. This makes it easier to bring the slit mating surfaces 25a into close contact with each other over their entire surfaces, thereby improving the magnetic characteristics of the stator core 11.

[0045] As shown in FIG. 22, the opposing side surfaces 25a1, 25a2 (slit mating surfaces) of the slit 25 may have a larger radius of curvature for the side surface 25a2 that will be subsequently deformed into an annular shape than the side surface 25a1 that will be initially deformed into an annular shape. This configuration allows the side surface 25a2 that will be subsequently deformed into an annular shape to conform to the side surface 25a1 that will be initially deformed into an annular shape, making it easier to bring the slit mating surfaces 25a1, 25a2 into close contact with each other over their entire surfaces. This improves the magnetic properties of the stator core 11.

[0046] FIG. 23 is a schematic diagram showing a modified example of the stator core 11. FIG. 23(b) shows an enlarged view of the R portion of FIG. 23(a). The radial direction D1 positions of the outer peripheral surfaces S1, S2, and S3 of the rectangular steel plate 20 deformed into an annular shape may be shifted from one another in the stacking direction D2. This configuration can increase the area of ​​the outer surface of the stator core 11, thereby improving the heat dissipation performance of the stator core 11. In the above configuration, the stator core 11 and the case may be fastened together by bolts or screws, rather than shrink-fitting (pressure-fitting) the case 15 onto the outer periphery of the stator core 11.

[0047] 24, the back yoke forming portion 21a of the rectangular steel plate 20 may be formed with two (or more) slits 25 at positions corresponding to the slots 23, each slit opening toward the slot 23. That is, in addition to the above embodiment, the back yoke forming portion 21a of the rectangular steel plate 20 may be formed with at least one slit 25 at a position corresponding to the slot 23, each slit opening toward the slot 23.

[0048] 25, the back yoke forming portion 21a of the rectangular steel plate 20 may be formed with one slit 25 for each of the plurality of slots 23, so that the slit 25 opens toward the slot 23. Note that the back yoke forming portion 21a of the rectangular steel plate 20 may be formed with multiple slits 25 for each of the plurality of slots 23, so that the slits 25 open toward the slot 23.

[0049] As shown in FIG. 26 , the back yoke 21 may be formed with at least one slit 25 that extends over 50% or more of the entire length of the back yoke 21 in the radial direction of the stator core 11 and opens to the outer circumferential side (outer diameter side). Furthermore, the base iron core 11q may be formed by rolling the base iron core 11p into a C-shape and joining the inner circumferential sides of the contact portions 11a of the circumferential end faces 11e of the base iron core 11p. The method of joining the contact portions 11a is not limited to welding, and may also be brazing, adhesive, crimping, or the like. Even in these cases, if the proportion of the joints among the contact portions 11a in the radial direction of the base iron core 11q is 50% or less of the entire contact portions 11a, the above-described embodiments and their modifications can be applied to achieve similar effects.

[0050] When the rectangular steel plate 20 shown in FIG. 27 is deformed into an annular shape as shown in FIG. 28, tensile stress acts on the outer diameter side of the neutral line N in the back yoke forming portion 21a, and compressive stress acts on the inner diameter side of the neutral line N. For this reason, as shown in FIG. 29, on the inner diameter side of the neutral line N, the back yoke forming portion 21a may buckle (bulge) in the thickness direction of the steel plate 20, causing a buckling portion 21b (bulge). This may cause wrinkles or undulations in the back yoke forming portion 21a.

[0051] 30, recesses 21c may be formed in the circumferential direction of the steel plate 20 (stator core 11) deformed into an annular shape at positions corresponding to the slits 25 of the back yoke forming portion 21a. With this configuration, when the rectangular steel plate 20 (element core 11p) is rolled into an annular (cylindrical) shape and deformed into a "C" shape, it is possible to prevent the steel plate 20 from expanding in the thickness direction. As a result, it is possible to prevent the steel plate 20 from wrinkling or swell.

[0052] For example, recess 21c is formed on the front side surface (one surface) of back yoke forming portion 21a. The planar shape of recess 21c can be a semicircle as shown in FIG. 31(a), an inverted triangle as shown in FIG. 31(b), a rectangle as shown in FIG. 31(c), or the like. The cross-sectional shape of recess 21c can be a trapezoid as shown in FIG. 32(a), a rectangle as shown in FIG. 32(b), or the like. Note that recess 21c may be formed on both the front side surface and the back side surface of back yoke forming portion 21a, as shown in FIG. 32(c).

[0053] As shown in FIGS. 33, 34(a), and 34(b), the back yoke 21 may be provided with thin portions 21d in which the thickness of the back yoke 21 in the direction of the central axis C1 of the stator core 11 is thinner than the thickness of the teeth 22. This configuration can be formed, for example, by rolling stacked rectangular steel plates 20 (element cores 11p) into an annular (cylindrical) shape, deforming them into a C-shape, and then pressing part or all of the back yoke 21 in the direction of the central axis C1 of the stator core 11. Therefore, even if wrinkles or undulations occur in the steel plates 20 when rolling the rectangular steel plates 20 into an annular shape and deforming them into a C-shape, they can be corrected by pressing. The thin portions 21d may be provided in the outer peripheral edge of the back yoke 21 as shown in FIG. 35(a) or the entire back yoke 21 as shown in FIG. 35(b).

[0054] 36, before bending the element core 11p into a cylindrical shape, both longitudinal ends of the element core 11p may be bent inward in advance. This configuration makes it easier to improve the circularity of the element core 11q.

[0055] As shown in Figure 37, the stator winding 12 may be assembled in advance as a winding assembly 12a. Then, as shown in Figure 38, the winding assembly 12a may be inserted into the slots 23 of the base iron core 11p, and the base iron core 11p may then be deformed into a cylindrical shape to form (manufacture) the stator 10, as shown in Figure 39. Note that the conductor wire undergoes work hardening when the winding assembly 12a is formed. For this reason, before deforming the base iron core 11p into a cylindrical shape, the winding assembly 12a may be subjected to a heat softening treatment to make the winding assembly 12a easier to deform.

[0056] Alternatively, a configuration may be adopted in which the opening width of the slots 23 is wider than the thickness of the conductor wire before the raw iron core 11p is deformed into a cylindrical shape, and the opening width of the slots 23 is narrower than the thickness of the conductor wire after the raw iron core 11p is deformed into a cylindrical shape. Furthermore, after the raw iron core 11p is deformed into a cylindrical shape, the tip ends of the teeth 22 may be deformed to further narrow the opening width of the slots 23. The conductor wire may be a rectangular wire or a round wire.

[0057] Furthermore, the stator winding 12 may be disposed inside the slot 23 closer to the outer diameter side, and a gap may be formed between the tip of the tooth 22 and the stator winding 12. Furthermore, the stator winding 12 may be configured inside the slot 23 so as to be divided into multiple layers in the radial direction.

[0058] The stator winding 12 may be concentratedly wound around the teeth 22. In addition, the length of the back yoke 21 in the radial direction of the stator core 11 may be 50% or more and less than 70% of the length of the teeth 22.

[0059] The stator core 11 may be composed of core portions 11A and 11B as shown in FIG. 40, or may be composed of core portions 11C to 11F as shown in FIG. 41. That is, the stator core 11 may be a divided core divided into a plurality of portions in the circumferential direction. In these cases, the number of abutment portions 11a and welded portions 11m (joint portions) provided on the stator core 11 is equal to the number of portions divided. The back yoke 21 is formed with at least one slit (not shown) extending in the radial direction of the stator core 11 over a length of 50% or more of the entire length of the back yoke 21. Even with such a configuration, it is possible to achieve the same effects as the above-described embodiment and its modifications.

[0060] The above modifications may be implemented in combination.

[0061] Characteristic configurations extracted from the above-described embodiment and modified examples will be described below. [Configuration 1] A stator (10) for a rotating electric machine includes a stator core (11) formed by joining an outer circumferential side or an inner circumferential side of abutting portions (11a) between circumferential end faces (11e) of stacked C-shaped steel plates (20), and a stator winding (12) inserted into a plurality of slots (23) formed in the stator core, The stator core includes a back yoke (21) extending in a circumferential direction around a central axis of the stator core, and a plurality of teeth (22) extending from the back yoke toward the central axis, and the slots are formed between adjacent teeth, the abutment portion is provided in a portion of the back yoke between adjacent teeth, In the radial direction of the stator core, the length of the joined portion (11 m) of the contact portion is 50% or less of the entire length of the contact portion, A stator for a rotary electric machine, wherein the back yoke has at least one slit (25) formed therein, the slit extending in the radial direction of the stator core over a length that is 50% or more of the entire length of the back yoke. [Configuration 2] 2. The stator of claim 1, wherein the length of the back yoke in the radial direction of the stator core is 70% or more of the length of the teeth. [Configuration 3] 3. The stator of the rotating electric machine according to configuration 1 or 2, wherein the stator winding is distributedly wound around the teeth. [Configuration 4] 4. The stator of any one of configurations 1 to 3, wherein a cylindrical housing (15) is fitted onto the outer periphery of the stator core. [Configuration 5] 5. The stator for a rotary electric machine according to any one of configurations 1 to 4, wherein a plurality of the contact portions are provided on the stator core. [Configuration 6] The outer periphery of the contact portion is joined, 6. The stator for a rotating electric machine according to any one of configurations 1 to 5, wherein the slits in the back yoke are open to an inner peripheral side. [Configuration 7] The stator of any one of configurations 1 to 6, wherein a back yoke forming portion (21a) that forms the back yoke in the "C"-shaped steel plate has a recess (21c) formed at a position corresponding to the slit in the circumferential direction of the stator core. [Configuration 8] The stator for a rotating electric machine according to any one of configurations 1 to 7, wherein the back yoke is provided with a thin portion (21d) in which the thickness of the back yoke is thinner than the thickness of the teeth in the central axis direction of the stator core. [Explanation of symbols]

[0062] 10... stator, 11... stator core, 11a... abutment portion, 11e... end face, 11m... welded portion, 12... stator winding, 20... steel plate, 21... back yoke, 22... teeth, 23... slot, 25... slit

Claims

1. A stator (10) for a rotating electric machine, comprising: a stator core (11) formed by joining the outer or inner circumferential sides of abutting portions (11a) of circumferential end faces (11e) of stacked "C"-shaped steel plates (20); and a stator winding (12) inserted into a plurality of slots (23) formed in the stator core, The stator core includes a back yoke (21) extending in a circumferential direction around a central axis of the stator core, and a plurality of teeth (22) extending from the back yoke toward the central axis, and the slots are formed between adjacent teeth, the abutment portion is provided in a portion of the back yoke between adjacent teeth, In the radial direction of the stator core, the length of the joined portion (11 m) of the contact portion is 50% or less of the entire length of the contact portion, A stator for a rotating electric machine, wherein the back yoke has at least one slit (25) formed therein, the slit extending in the radial direction of the stator core over a length equal to or greater than 50% of the entire length of the back yoke.

2. 2. The stator of claim 1, wherein the length of the back yoke in the radial direction of the stator core is 70% or more of the length of the teeth.

3. 3. The stator of claim 1, wherein the stator winding is distributed around the teeth.

4. 3. The stator of claim 1, wherein a cylindrical housing (15) is fitted onto an outer periphery of the stator core.

5. The stator of claim 1 or 2, wherein the stator core is provided with a plurality of the contact portions.

6. The outer periphery of the contact portion is joined, 3. The stator for a rotating electric machine according to claim 1, wherein the slits in the back yoke are open to an inner peripheral side.

7. 3. The stator of claim 1, wherein a back yoke forming portion (21 a) that forms the back yoke in the C-shaped steel plate has a recess (21 c) formed at a position corresponding to the slit in the circumferential direction of the stator core.

8. 3. The stator for a rotating electric machine according to claim 1, wherein the back yoke is provided with thin portions (21d) in which the thickness of the back yoke is thinner than the thickness of the teeth in the central axis direction of the stator core.

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