Stator, method of manufacturing stator, method of manufacturing AC rotating electric machine, induction motor and blower

Abstract

To provide a structure and a manufacturing method of a stator which can reduce the height and weight of a coil end in an induction motor, can be easily manufactured, and can increase the efficiency of the motor.SOLUTION: A stator includes an inner core formed by laminating thin plates of electromagnetic steel sheets and formed into an annular shape by connecting a plurality of radially extending inner core pieces 4a via a thin portion, a coil 8 inserted into a slot formed between adjacent inner core pieces, and an annular outer core that connects the outer diameters of plurality of inner core pieces, and the coil is arranged such that the distance between a first coil end projecting from one surface of the inner core and the one surface is longer than the distance between a second coil end projecting from the opposite surface of the inner core and the opposite surface.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present application relates to a stator, a method for manufacturing a stator, a method for manufacturing an AC rotating electric machine, an induction motor, and a blower. [Background technology]

[0002] In an electric motor, the coil ends outside the stator core are not linked to the magnetic circuit. Therefore, the magnetic flux generated by the coil ends becomes leakage flux, which not only reduces the power factor but also increases the coil circumference and increases resistance. Therefore, it is important to reduce the coil ends.

[0003] In general electric motors, the coil is inserted between the slots using an insert method, so it is necessary to leave some margin in the coil circumference, which is known to result in large coil ends.To lower the coil ends, there is a method in which the stator core is divided into an outer ring yoke part and an inner ring magnetic pole part, and the coil is wound directly around the insulating material of the inner ring magnetic pole part (see, for example, Patent Document 1).

[0004] Furthermore, if a stator core is divided into partial circles that form a part of the stator core, it can be applied to lap winding with lower coil ends (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-6959 [Patent Document 2] JP 2009-254133 A Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, in a distributed winding motor, the fixed core can be divided into an inner ring and an outer ring to achieve low coil end lap winding, but it is difficult to further reduce the coil end height and circumference. In addition, because the teeth are separate, handling is difficult, including determining the position of each one.

[0007] The present application has been made to solve the above-mentioned problems, and has as its object to provide a stator that enables the coil end to be low-profile, a method for manufacturing a stator, a method for manufacturing an AC rotating electric machine, an induction motor, and a blower. [Means for solving the problem]

[0008] The stator disclosed in the present application is The coil is arranged so that the distance between a first coil end protruding from one surface of the inner core and the one surface is longer than the distance between a second coil end protruding from the opposite surface of the inner core and the opposite surface. The coil is arranged so that the distance between a first coil end protruding from the opposite surface of the inner core and the opposite surface is longer than the distance between a second coil end protruding from the opposite surface of the inner core and the opposite surface. And, a space between one surface of the inner core and the first coil end has a length that allows the inner core to be bent toward the outer diameter side, and the second coil end is disposed in a straight line along the opposite surface of the inner core; a portion of the second coil end is disposed inside the inner diameter of the annular inner core; The first coil end is bent toward the outer diameter side of the inner core so as not to impede the axial insertion of the rotor, and is disposed outside the inner diameter of the annular inner core. It is characterized by: Effect of the Invention

[0009] According to the stator disclosed in the present application, the coils are arranged so that the distance between the first coil end protruding from one face of the inner core and that face is longer than the distance between the second coil end protruding from the opposite face of the inner core and the opposite face, thereby making it possible to reduce the height of the coil ends. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a top view of the stator core. [Diagram 2] 2 is a top view of the inner core and the outer core that constitute the stator core. FIG. [Diagram 3] 3 is a side view of the linear inner core according to the first embodiment. FIG. [Figure 4] 3 is a view showing two adjacent inner cores according to the first embodiment as viewed from the inner diameter side. FIG. [Diagram 5] FIG. 2 is a diagram illustrating the shape of a coil according to the first embodiment. [Figure 6] 5A to 5C are diagrams illustrating insertion of a coil into a linear inner core in accordance with the first embodiment. [Figure 7] 5A to 5C are diagrams illustrating insertion of a coil into a linear inner core in accordance with the first embodiment. [Figure 8] 5A to 5C are diagrams illustrating a process for forming the linear inner core into an annular shape according to the first embodiment. [Figure 9] 5A to 5C are diagrams illustrating the arrangement of coils relative to an inner core according to the first embodiment. [Figure 10] 6A to 6C are diagrams illustrating a coil insertion process after the inner core in accordance with the first embodiment is shaped into a circular ring. [Figure 11] 3 is a diagram showing a configuration of a stator according to the first embodiment. FIG. [Figure 12] 3 is a diagram showing the coil in the slot according to the first embodiment as viewed from both sides of the annular inner core. FIG. [Figure 13] 5A to 5C are diagrams illustrating the relationship between the stator, an inner diameter jig, and coils according to the first embodiment. [Figure 14] 5A to 5C are diagrams illustrating a configuration in which a coil end according to the first embodiment is tilted toward the outer diameter side of an inner core. [Figure 15] FIG. 2 is a top view of the rotor according to the first embodiment. [Figure 16] 2 is a diagram showing a state in which a rotor is inserted into a stator according to the first embodiment, as viewed from above. FIG. [Figure 17]3 is a diagram showing a die layout for the stator core and rotor core according to the first embodiment. FIG. [Figure 18] 5 is a diagram illustrating a state in which the stator core and the rotor core according to the first embodiment have been punched together. FIG. [Figure 19] 1 is a diagram illustrating the configuration of an induction motor using a stator according to a first embodiment. [Figure 20] 1 is a side view of a blower using a stator according to a first embodiment. [Figure 21] 10A and 10B are diagrams illustrating the configuration of a linear outer core according to the second embodiment. [Figure 22] 13 is a view showing two adjacent outer cores according to the second embodiment as viewed from the inner diameter side. FIG. [Figure 23] 13 is a diagram illustrating a die layout for a linear outer core according to the second embodiment. FIG. [Figure 24] 10 is a diagram illustrating a die layout for a linear inner core according to the second embodiment. FIG. [Diagram 25] 10A and 10B are diagrams illustrating the structure of the inner diameter side of an outer core according to the second embodiment. [Figure 26] FIG. 11 is a top view of the stator according to the second embodiment. [Figure 27] 10A and 10B are diagrams illustrating the shape of teeth of an inner core according to a second embodiment. [Figure 28] 13 is a diagram illustrating the layout of dies for a linear inner core and an outer core divided into four according to embodiment 3. FIG. [Figure 29] 13 is a diagram illustrating positions of holes formed in an outer core divided into four parts according to embodiment 3. FIG. [Diagram 30] 13 is a diagram illustrating the stacking of the outer core divided into four parts according to the third embodiment. FIG. [Diagram 31] FIG. 11 is a top view of a stator according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, preferred embodiments of the stator according to the present invention will be described with reference to the drawings. The same reference numerals are used to designate the same contents and corresponding parts, and detailed descriptions thereof will be omitted. In the following embodiments, the same reference numerals are used to designate the same components, and redundant descriptions will be omitted.

[0012] First embodiment Figure 1 shows a stator core 3 which is composed of two parts, an inner core 1 and an outer core 2. That is, as shown in Figures 2(a) and (b), this core structure involves inserting a preformed coil into the inner core 1 by dropping it in from the outer diameter side or the inner diameter side, or winding it directly around the inner core 1, and then connecting the annular outer core 2 to the inner core 1 to form the stator core 3 in Figure 1.

[0013] In contrast, in the inner core 4 of the stator shown in Fig. 3, adjacent inner core pieces 4a are connected by thin-walled parts 5 at the tips on the inner diameter side and are arranged in a straight line. With this structure, a slot 6 for inserting a coil is formed between adjacent inner core pieces 4a. The inner core 4 is punched out of a roll of electromagnetic steel sheet using a die press. The grade of the electromagnetic steel sheet is not limited here.

[0014] Fig. 4 shows two adjacent inner core pieces 4a viewed from the inner diameter side. The inner core 4 is formed by laminating thin plates 7 of electromagnetic steel sheets. The thin-walled portion 5 connecting the adjacent inner core pieces 4a may be formed from one or more of the laminated thin plates 7, and may be formed from any layer of the laminate. The thickness of the thin plates is not limited here. The thin plates 7 between the laminated layers can be fixed by methods such as caulking or bonding, but these are not limited here.

[0015] Next, the shape of the coil 8 to be inserted into each slot 6 will be described with reference to Fig. 5. The coil 8 is formed in advance by winding magnet wire around a bobbin or the like. In this embodiment, a round copper wire is used as the magnet wire. Various types and diameters of magnet wire can be used depending on the size of the stator, the type of motor, etc.

[0016] As shown in Fig. 6, in this embodiment, the coil 8 is inserted into a predetermined slot 6 from the right side in the figure so as to form a lap winding in a stator with 16 slots. Here, for convenience of explanation, the coil 8 is shown with the number of turns of the winding of the coil 8 between the slots being 1. For convenience of explanation, this expression may also be used in other figures.

[0017] 7, the inner core pieces 4a are arranged in a straight line and are perpendicular to the coil 8, making insertion easy. As described above, the inner core pieces 4a are connected by the thin-walled portions 5, making it easy to manipulate the inner core 4 during insertion.

[0018] Next, with coils 8 inserted into all slots 6, as shown in Fig. 8, the inner diameter side of the inner core 4 is aligned with the outer periphery of the inner diameter jig 11 from the side where one layer of coils 8 is inserted (the left side of Fig. 6), and the inner core 4 connected by the thin-walled portion 5 is rotated around the inner diameter jig 11. During rotation, the thin-walled portion 5 bends and moves along the inner diameter jig 11, and rotates while connecting the inner core pieces 4a. For this reason, the thin-walled portion 5 needs to have a width large enough that it will not break due to the stress of a single bending.

[0019] When the inner core 4 is rotated, the coils 8 inserted in each slot 6 shown in Fig. 9(a) are pulled to one side by applying a force in the direction of arrow A (perpendicular to one surface of the inner core 4) in the cylindrical axial direction (height 9 direction) of the inner diameter jig 11 as shown in Fig. 9(b). As a result of the pulling, the coil 8 is deformed, and the length of the coil 8 in the circumferential direction 10 also changes according to the pulling in the direction of arrow A.

[0020] In other words, the coil 8 sticks to the inner core piece 4a, the length of the coil end on the side being pulled in the direction of arrow A becomes longer than the opposite side, and a gap 12 is formed between the inner core piece 4a and the coil 8. In order to pull the coil 8, when the coil 8 is formed in advance on the bobbin, it is necessary to form the coil 8 so that the length of the coil 8 is larger than the sum of the circumferential direction 10 and height 9 of the multiple inner core pieces 4a into which the coil 8 will be inserted.

[0021] As shown in Fig. 8, when the inner core 4 is rotated along the inner diameter jig 11, the coil 8 overlaps above the inner diameter jig 11, so the height of the inner diameter jig 11 needs to be the same as or lower than the axial height 9 of the inner core 4 laminated with the thin plates 7. Although not shown in the figure, it is sufficient that the support portion which is the rotation axis of the rotating inner diameter jig 11 does not come into contact with the coil 8. Here, the support portion of the inner diameter jig 11 will not be described in detail.

[0022] When the inner core 4 is formed into an annular shape along the inner diameter jig 11, the inner core pieces 4a that are not connected by the thin-walled portions 5 shown in Fig. 4 come into contact with each other, forming joints 13 as shown in Fig. 10. These joints 13 are joined to complete the annular inner core 4. The method for joining the inner core pieces 4a is not limited here.

[0023] When the inner core 4 becomes annular, the coils 8 not yet inserted in the slots 6 shown on the right side of Fig. 6 are inserted as shown by the arrows in Fig. 10 into the slots 6 where only one layer of coils 8 was inserted as shown on the left side of Fig. 8, until all of the coils 8 are inserted into the slots 6. Next, the outer core 14 is press-fitted onto the outer diameter side of the annular inner core 4, forming a stator 15 as shown in Fig. 11. In Fig. 11, the windings in the direction connecting the slots of the coils 8 are omitted.

[0024] In the stator 15 thus formed, the side of the coil 8 shown in FIG. 9(b) on which the coil end protruding from one surface of the inner core 4 is long is shown in FIG. 12(a) as the side 16 on which the core bar or rotor is inserted, and the opposite side is shown in FIG. 12(b) as the side 17 on which the rotor is not inserted. In FIG. 12(a) on the side 16 on which the rotor is inserted, the coil end passing through the inner diameter side in the slot is arched, and the coil end is located with a gap 12 from one surface of the inner core 4. In contrast, in FIG. 12(b) on the side 17 on which the rotor is not inserted, the coil end passing through the inner diameter side in the slot is arranged in a straight line along the opposite surface of the inner core 4. However, in both the side 16 on which the rotor is inserted and the side 17 on which the rotor is not inserted, the coil end is present on the inner diameter side of the slot, that is, above the inner diameter jig 11, as shown in FIG. 13, so that the inner diameter jig 11 cannot be removed in this state.

[0025] Therefore, as shown in Fig. 14, the coil end on the side 16 where the rotor is inserted is tilted toward the outer diameter side of the stator 15, making it possible to remove the inner diameter jig 11. That is, each of the coil ends of the coil 8 on the side 16 where the rotor is inserted that has been pulled toward the outer diameter side of the inner core 4 is bent. The force required to bend the coil ends varies depending on the size of the gap 12 between the coil ends and the inner core 4, so appropriate adjustments are required. When bending the coil ends, a mirror finish is applied to the bending jig used to bend the coils 8 without destroying their insulating coating, and the bending speed must also be adjusted, but this is not limited to this and will not be described in detail here.

[0026] In this way, compared to when all of the coil ends on both sides of the stator 15, the side 16 where the rotor is inserted and the side 17 where the rotor is not inserted, are arranged above the inner core 4 with a certain amount of gap, the coil ends on the side 17 where the rotor is not inserted are arranged in a straight line passing through the inner diameter side within the slot, and only the coil ends on the side 16 where the rotor is inserted are arranged above the inner core 4 with a gap, which makes it possible to shorten the circumferential length of the coil 8, thereby shortening the axial length of the motor and reducing the weight by reducing the amount of copper.

[0027] In this embodiment, the outer core 14 is pressed into the inner core 4 with the inner diameter jig 11 placed inside the stator 15. However, before pressing in the outer core 14, the coil end may be tilted down, the inner diameter jig 11 may be temporarily removed, and then a dedicated core bar that supports the inner diameter of the inner core 4 may be inserted to improve the pressing accuracy or to divide the process, and then the outer core 14 may be pressed in.

[0028] In addition, when rotating the inner core 4 connected by the thin-walled portion 5 while aligning the inner diameter side of the inner core 4 with the inner diameter jig 11, the coils 8 inserted in each slot 6 may be pulled to one side in the axial direction 9 of the coil, and at the same time, the coil ends may be tilted toward the outer diameter side, as shown in Figure 9(b).

[0029] With one coil end on one axial side tilted down, rotor 18 shown in Fig. 15 is inserted into stator 15. Rotor 18 is in a state where an aluminum bar is formed by aluminum die casting into a cage-shaped rotor core 19, shaft 20 is press-fitted, and bearings are attached to both ends of the shaft, but the detailed structure of rotor 18 is not limited here.

[0030] As shown in FIG. 16, after the rotor 18 is inserted, the frame and bracket that cover the stator 15 and the rotor 18 are attached, but depending on the structure of the frame and bracket, the coil end on one side that is tilted to the outer diameter side may be returned to above the rotor 18. Also, the coil end on the side 16 where the rotor is inserted may be fixed with varnish or lacing as necessary so as to not move. The coil end on the side 17 where the rotor is not inserted is straight with little slack on the inner diameter side, but may also be fixed with varnish or lacing as necessary so as not to move. Also, although not described in detail in this embodiment, the coil 8 may be inserted after attaching an insulating member for insulating the electromagnetic steel plate and the coil 8 to each inner core piece 4a.

[0031] The inner core 4 and the outer core 14 are formed by punching out rolled electromagnetic steel sheet material with a die. As shown in Fig. 17, the outer core 14, the inner core 4 in an annular shape, and the rotor core 19 are punched together. This punching process improves the fit between the outer core 14 and the inner core 4 when they are press-fitted. After punching, as shown in Fig. 18, one location of the thin-walled portion 5 of the annular inner core 4 is cut off and aligned in a straight line, and the coil 8 is inserted or directly wound. In addition, since the inner cores 1 shown in FIG. 1 have gaps between adjacent inner cores on the inner diameter side, after inserting the coils and forming the stator core 3, the work of inserting wedges is required to prevent the inserted coils from leaking out to the inner diameter side. However, in this embodiment, the inner cores 4 are connected by thin-walled portions 5, so that the coils 8 will not leak out to the inner diameter side, and therefore the work of inserting wedges is not required.

[0032] By mounting the stator 15, it is possible to provide an induction motor 31 that has a low coil end, is highly efficient, lightweight, and is easy to manufacture, as shown in Fig. 19. By mounting this induction motor 31 on a blower 32, for example, as shown in Fig. 20, it is possible to provide an energy-saving ventilation fan.

[0033] Embodiment 2 The stator structure and manufacturing method according to embodiment 2 will be described below. In embodiment 1, outer core 14 was an annular one-piece body, but in embodiment 2, as shown in Fig. 21, like inner core 4 in embodiment 1, divided outer core pieces 21a are arranged in a straight line in the same number as inner core pieces 4a, and each outer core piece 21a is connected by a thin portion 22 at the tip part on the outer diameter side. As shown in Fig. 22, like inner core piece 4a, outer core piece 21a is formed by laminating thin electromagnetic steel sheets 23.

[0034] As shown in Figures 23 and 24, the inner core 24 and the outer core 21 are punched out using a die press, and the inner core 24 and the outer core 21 connected in a daisy chain are separated at the thin-walled portions 22 as many as necessary and stacked to form the inner core 24 and the outer core 21. The thin-walled portions 22 connecting adjacent outer core pieces 21a need only be formed from one or more of the stacked thin plates 23, and may be formed from any of the stacked layers. The thickness of the thin plates 23 is not limited here. Methods such as caulking and adhesive are known for fixing the thin plates 23 between the layers, but are not limited here.

[0035] After the inner core 24 is formed into a circular ring shape, the outer core 21, which is similarly arranged in a straight line, is formed into a circular ring shape. When the outer core 21 is formed into a circular ring shape, the position is determined by the contact surfaces of the outer core pieces 21a, so the jig used to form the inner core 24 into a circular ring is not necessary, although it may be used depending on the desired accuracy.

[0036] The inner core 24 and the outer core 21 are formed into an annular shape, and the parts that are not connected by the thin-walled parts 22 are joined together. If the joints of the inner core 24 and the outer core 21 are located at the same position in the circumferential direction, there is a possibility that the mechanical strength may decrease. Therefore, the positions of the inner core 24 and the outer core 21 in the circumferential direction are determined so that the joints of the inner core 24 and the outer core 21 are located at different positions. Also, as shown in Figs. 25(a) and (b), a positioning groove may be provided on the inner diameter of the outer core 21 at the part where the outer diameter side of the inner core 24 and the inner diameter side of the outer core 21 contact, or as shown in Fig. 25(c), a concave-convex groove may be provided in which the inner core 24 and the outer core 21 fit together. The annular inner core 24 and the outer core 21 are press-fitted to form a stator 25 as shown in Fig. 26. The coil insertion and coil end bending are performed in the same manner as described in the first embodiment.

[0037] As described above, when the outer core 21 and the inner core 24 of the second embodiment are punched out by a die press, each has a linear shape, and the outer core 21 is arranged parallel to the rolling direction of the electromagnetic steel sheets as shown in Fig. 23. Also, the inner core 24 is arranged perpendicular to the rolling direction of the electromagnetic steel sheets as shown in Fig. 24.

[0038] This is because the magnetic steel sheets used are oriented magnetic steel sheets that have extremely excellent magnetic properties only in the rolling direction. As a result, magnetic flux flows in the circumferential direction of outer core 21 when it is formed into a ring shape, so by arranging them in a straight line parallel to the rolling direction, it is possible to obtain excellent magnetic properties in the circumferential direction of outer core 21 when it is formed into a ring shape.

[0039] Similarly, when the inner core 24 is formed into a ring shape, a lot of magnetic flux flows in each of the teeth 26 shown in Fig. 27, so by arranging them in a line and perpendicular to the rolling direction, it is possible to obtain excellent magnetic properties in the teeth 26 of each of the inner cores 24 when formed into a ring shape, and it is possible to reduce leakage magnetic flux flowing in the thin-walled portions 27 of the inner core 24, making it possible to further improve the efficiency of an induction motor equipped with the stator 25 of this embodiment. Also, the inner core 24 and outer core 21 are arranged in a line, and there are few gaps between them, making it possible to arrange them in a mold, resulting in extremely high yields.

[0040] Third embodiment The stator structure and manufacturing method according to embodiment 3 will be described below. While outer core 14 in embodiment 1 is an annular one-piece body, embodiment 3 uses outer core pieces 28a obtained by dividing an annular outer core into four as shown in Fig. 28. In this embodiment, the grade of the electromagnetic steel sheet is not limited.

[0041] Dividing the outer core 28 into four allows the outer core pieces 28a to be positioned in a die with fewer gaps, and the inner core 29 can also be positioned in a die with fewer gaps, resulting in a high yield. The outer core pieces 28a may be connected to each other by providing them with matching concave and convex grooves as described in the second embodiment, and then positioning them for connection.

[0042] Also, since the annular outer core 28 is divided into four as shown in Fig. 29, holes or outer peripheral grooves can be provided at positions 45 degrees from the center of each outer core piece 28a, and the four divided outer core pieces 28a can be connected together by alternately stacking them every 45 degrees as shown in Fig. 30 and fixing the holes with rivets, or welding to the outer peripheral grooves, or fixing with strap rivets, etc. The four divided outer core pieces 28a are formed into an annular shape, and the coils are inserted into the inner core 29 and the coil ends are bent in the same manner as described in embodiment 1, and the outer core 28 is press-fitted into the inner core as shown in Fig. 31 to form a stator.

[0043] Although the present application describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless modifications not exemplified are assumed within the scope of the technology disclosed in the present specification, including, for example, modifying, adding, or omitting at least one component, and further, extracting at least one component and combining it with a component of another embodiment. [Explanation of symbols]

[0044] 1, 4, 24, 29: inner core, 2, 14, 21, 28: outer core, 3: stator core, 4a: inner core piece, 5, 22, 27: thin wall portion, 6: slot, 7, 23: thin plate, 8: coil, 11: inner diameter jig, 12: gap, 13: joint, 15, 25: stator, 18: rotor, 19: rotor core, 20: shaft, 21a, 28a: outer core piece, 26: teeth portion, 31: induction motor, 32: blower

Claims

1. the coil is arranged such that a distance between a first coil end protruding from one surface of the inner core and the one surface is longer than a distance between a second coil end protruding from the opposite surface of the inner core and the opposite surface, a space between one surface of the inner core and the first coil end has a length that allows the inner core to be bent toward an outer diameter side, and the second coil end is disposed linearly along an opposite surface of the inner core, a portion of the second coil end is disposed inside an inner diameter of the annular inner core, A stator characterized in that the first coil end is bent toward the outer diameter side of the inner core so as not to interfere with axial insertion of the rotor, and is positioned outside the inner diameter of the annular inner core.

2. 2. The stator according to claim 1, wherein the outer core is formed by laminating thin electromagnetic steel sheets and connecting a plurality of outer core pieces via thin portions.

3. A method for manufacturing a stator, comprising stacking thin electromagnetic steel sheets, arranging a plurality of inner core pieces connected to each other via thin-walled portions in a linear manner, inserting a coil formed by winding a predetermined number of windings into a slot formed between adjacent inner core pieces, and before joining the inner core pieces at both ends arranged in a linear manner to form a circular inner core, pulling the coil in a direction perpendicular to one face of the inner core to deform the coil so that a distance between a first coil end protruding from one face of the inner core and the one face is longer than a distance between a second coil end protruding from the opposite face of the inner core and the opposite face.

4. 4. The method for manufacturing a stator according to claim 3, further comprising press-fitting an annular outer core into outer diameter ends of the inner core pieces extending in the radial direction of the annular inner core.

5. 5. The method for manufacturing a stator as described in claim 4, characterized in that the outer core is formed by stacking thin electromagnetic steel sheets, and the same number of outer core pieces as the inner core pieces are connected in a straight line via thin-walled portions, and the outer core pieces at both ends of the straight line are joined to form a circular ring shape.

6. 6. The method for manufacturing a stator according to claim 5, wherein the joint portion of the annular inner core and the joint portion of the annular outer core are disposed at different positions in the circumferential direction.

7. The method for manufacturing a stator as described in claim 5, characterized in that the electromagnetic steel sheets forming the inner core pieces and the outer core pieces are oriented electromagnetic steel sheets, and when the inner core pieces are formed by die pressing, they are arranged in a straight line perpendicular to the rolling direction and punched out, and when the outer core pieces are formed by die pressing, they are arranged in a straight line parallel to the rolling direction and punched out.

8. 5. The method for manufacturing a stator as described in claim 4, characterized in that the annular outer core is formed by punching out four arc-shaped outer core pieces using a die press and stacking them, and connecting portions are formed to connect the four arc-shaped outer core pieces to each other.

9. a coil formed by winding a predetermined number of turns of wire into a slot formed between adjacent inner core pieces; before joining the linearly arranged inner core pieces at both ends to form a circular inner core, the coil is deformed by pulling the coil in a direction perpendicular to one face of the inner core so that a distance between a first coil end protruding from one face of the inner core and the one face is made longer than a distance between a second coil end protruding from an opposite face of the inner core and the opposite face; and when inserting a rotor into the circular inner core, the first coil end is bent toward the outer diameter of the inner core.

10. 10. The method for manufacturing an AC rotating electric machine according to claim 9, further comprising the step of: bending the first coil end bent toward the outer diameter side of the inner core toward the inner diameter side of the inner core after inserting a rotor.

11. An induction motor equipped with the stator according to claim 1 or 2.

12. A blower equipped with the induction motor according to claim 11.

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