WO2022118508A1

WO2022118508A1 - Dynamo electric machine stator, and method for manufacturing dynamo electric machine stator

Info

Publication number: WO2022118508A1
Application number: PCT/JP2021/032023
Authority: WO
Inventors: 章人戸谷; 明鳥羽; 奨太川口; 健一中山; 勇輝熊田; 康彦木村
Original assignee: 日立Astemo株式会社
Priority date: 2020-12-01
Filing date: 2021-08-31
Publication date: 2022-06-09
Also published as: JPWO2022118508A1; CN116615856A

Abstract

This dynamo-electric machine stator comprises a cylindrical stator core in which a plurality of slots are formed, and a plurality of segment coils inserted in the slots layered along the radial direction of the stator core, wherein: in one end of the stator core, the segment coils have a first bent part that is bent facing the stator core, a second bent part that is formed at the side closest to a connecting part, and an oblique part between the first bent part and the second bent part formed between the connecting part connected to another segment coil and an insertion part arranged inside the stator core; the segment coils include a first segment coil positioned at a prescribed layer among the layers, and a second segment coil positioned at the same layer as the first segment coil; the distance from the end surface of the stator core to the second bent part in the second segment coil is the same as the distance from the end surface of the stator core to the second bent part in the first segment coil; and the length of the oblique part in the second segment coil is different from the length of the oblique part in the first segment coil.

Description

Manufacturing method of stator of rotary electric machine and stator of rotary electric machine

The present invention relates to a stator of a rotary electric machine and a method of manufacturing a stator of a rotary electric machine.

Rotating electric machines such as motors and generators are constantly required to improve performance and reduce costs. Improving productivity is one of the means of cost reduction. Patent Document 1 uses an annular stator core having a plurality of slots arranged along the inner peripheral direction, and a plurality of conductor segments inserted across two predetermined slots separated by predetermined slot intervals. , A plurality of stator coils that are wound around the stator core while sequentially joining the tips of the respective conductor segments at the axial end of the stator core to form a joint, and are inserted across two predetermined slots. A plurality of joints formed by joining adjacent conductor segments to each other have different axial heights of the joints arranged adjacent to each other in the radial direction of the stator core, and the axial heights are high. A rotary electric stator is disclosed in which a joint portion and a joint portion having a low axial height are alternately arranged along a radial direction.

Japanese Patent Application Laid-Open No. 2015-119535

In the invention described in Patent Document 1, there is room for study in the productivity of the segment coil.

The stator of the rotary electric machine according to the first aspect of the present invention is inserted into the slot in a cylindrical stator core in which a plurality of slots are formed, and in layers along the radial direction of the stator core. A stator of a rotary electric machine including a plurality of segment coils, at one end of the stator core, the segment coil is arranged inside a connection portion connected to another segment coil and the stator core. Between the insertion portion, the first bending portion that bends toward the stator core, the second bending portion formed on the side closest to the connection portion, and the first bending portion and the second bending portion. A diagonal portion between the layers is formed, and includes the first segment coil located in a predetermined layer of the layers and the second segment coil located in the same layer as the first segment coil, and includes the second segment coil. The distance from the end face of the stator core to the second bent portion in the segment coil is the same as the distance from the end face of the stator core to the second bent portion in the first segment coil, and the second segment. The length of the skew portion in the coil is different from the length of the skew portion in the first segment coil.
In the method for manufacturing a stator of a rotary electric machine according to the second aspect of the present invention, the stator core in which a plurality of slots are formed and the stator core are inserted into the slots in layers along the radial direction of the stator core. A method for manufacturing a stator of a rotary electric machine including a plurality of segment coils, wherein the first segment coil and the second segment coil in which the axial length of the rotary electric machine is formed to be larger than that of the first segment coil are described above. The second segment coil is fixed by moving the jig in the circumferential direction of the stator core, the first step of inserting the jig into the slot, and the second step of bringing the jig into contact with the second segment coil. A third step of tilting the child core in the circumferential direction and a first step of moving the stator in the axial direction of the stator core to bring the first segment coil into contact with the jig in addition to the second segment coil. The four steps include a fifth step of tilting the first segment coil and the second segment coil in the circumferential direction by moving the jig in the circumferential direction of the stator core.

According to the present invention, the productivity of the segment coil can be improved.

External view of the stator Schematic diagram showing a segment coil Diagram showing multiple segment coils across layers The figure which shows the connection part of each phase The figure which shows the relationship between the 1st segment coil and the 2nd segment coil. The figure which shows the molding method of a segment coil The figure which shows the segment coil in 2nd Embodiment

-First embodiment-
Hereinafter, the first embodiment of the method for manufacturing the stator of the rotary electric machine and the stator of the rotary electric machine will be described with reference to FIGS. 1 to 6.

FIG. 1 is an external view of a stator 100 used in a rotary electric machine, for example, a permanent magnet type brushless motor. The stator 100 includes a stator core 20 and a plurality of segment coils 30. However, in FIG. 1, the segment coil 30 shows only one of the three phases. The stator core 20 has a hollow cylindrical shape. The stator core 20 has a plurality of slots 21, and a plurality of segment coils 30 are inserted into the respective slots 21 at different positions in the radial direction. That is, the segment coil 30 forms a plurality of cylindrical layers having the same center as the stator core 20. Hereinafter, this layer is referred to as a "layer". The "layer" can also be said to be a cylindrical layer composed of a group of segment coils 30 having the same radial position.

FIG. 2 is a schematic diagram showing the segment coil 30. FIG. 2A is a diagram showing the shape of the segment coil 30, and FIG. 2B is a diagram showing two segment coils 30 inserted into the slot 21. The segment coil 30 is used by bending a linear coil as shown in FIG. 2A. Each segment coil 30 has a connecting portion 31, an inserting portion 32, an oblique portion 33, a first bent portion 34, and a second bent portion 35.

The connection portion 31 is a portion connected to another segment coil 30 at one end of the stator core 20. The insertion portion 32 is a portion to be inserted inside the stator core 20. The first bending portion 34 is a portion that bends toward the stator core 20. The second bent portion 35 is a portion that bends toward the connecting portion 31, and is also a portion that is closest to the connecting portion 31 among the bent portions of the segment coil 30. The oblique portion 33 is a portion between the first bent portion 34 and the second bent portion 35. In FIG. 2, the first bent portion 34 and the second bent portion 35 are described as connecting portions of two straight lines, but actually draw an arc. Hereinafter, the length of the skewed portion 33 is referred to as a “skewed portion length” 33L.

As shown in FIG. 2B, the segment coil 30 is connected to other adjacent segment coils 30 and the connection portions 31 to each other. The distance between adjacent slots 21 is called a "slot pitch" and is used as a unit of length in the present embodiment. Hereinafter, the distance between the connection portion 31 and the insertion portion 32 is referred to as a “twist amount” T. In the two segment coils 30 shown in FIG. 2, the insertion portions 32 are separated from each other by 5 slot pitches. Therefore, the twist amount T of these segment coils 30 is 2.5 slot pitch.

The segment coil 30 included in the stator 100 has one of two twist amounts T. Here, the two twist amounts T are referred to as a standard twist amount Ts and an excess twist amount Tt for convenience. Further, in the following, the segment coil 30 in which the twist amount T is the standard twist amount Ts is referred to as the first segment coil 30A, and the segment coil 30 in which the twist amount T is the excess twist amount Tt is referred to as the second segment coil 30B.

The majority of the segment coils 30 included in the stator 100 are the first segment coils 30A, and the second segment coils 30B exist only at locations that straddle the layers. However, all the segment coils 30 straddling the layers do not have to be the second segment coil 30B. In other words, in at least one of the segment coils 30 straddling the layers, the twist amount T is not the standard twist amount Ts. In the present embodiment, the standard twist amount Ts will be set to 2.5 slot pitch, and a specific description will be given.

FIG. 3 is a diagram showing a plurality of segment coils 30 straddling layers. FIG. 3 (a) and FIG. 3 (b) differ only in the hatch position. This hatch shows the segment coil 30 of interest. In FIG. 3A, the hatched segment coil 30 corresponds to the second segment coil 30B when the standard twist amount Ts is 2.5 slot pitch because the insertion portions 32 are separated from each other by 6 slot pitch. In FIG. 3B, the hatched segment coil 30 corresponds to the first segment coil 30A when the standard twist amount Ts is 2.5 slot pitch because the insertion portions 32 are separated from each other by 5 slot pitch. In this way, the first segment coil 30A and the second segment coil 30B may be mixed in the segment coil 30 straddling the layers.

FIG. 4 is a diagram showing a connection portion of each phase. In this embodiment, both phases have a second segment coil 30B at the ends of the innermost and outermost layers. The second segment coils 30B on the innermost circumference are connected to each other by the connecting member C to form a neutral wire. In FIG. 4, the second segment coil 30B on the innermost circumference of the U phase is represented by the reference numeral 30B-U, the second segment coil 30B on the innermost circumference of the V phase is represented by the reference numeral 30B-V, and the innermost circumference of the W phase is represented by the reference numeral 30B-V. The second segment coil 30B of the above is represented by reference numeral 30B-W.

FIG. 5 is a diagram showing the relationship between the first segment coil 30A and the second segment coil 30B. Most of the segment coils 30 shown in FIG. 5 are the first segment coils 30A, and only one shown in the substantially center is the second segment coil 30B. In all the segment coils 30 shown in FIG. 5, the insertion portion 32 is inserted into the stator core 20. The distance Y from the end face of the stator core 20 to the second bent portion 35 is common to the first segment coil 30A and the second segment coil 30B. In other words, the distance in the central axis direction of the stator core 20 from the first bent portion 34 to the second bent portion 35 in the state where the segment coil 30 is inserted into the stator core 20 is the first segment coil 30A and the first. Common to the 2-segment coil 30B.

Further, as described above, the second segment coil 30B has a longer twist amount T than the first segment coil 30A. Therefore, the oblique portion length 33L of the second segment coil 30B is longer than the oblique portion length 33L of the first segment coil 30A. As shown in FIG. 4, the distance from the second bent portion 35 to the connecting portion 31 is longer in the second segment coil 30B than in the first segment coil 30A.

FIG. 6 is a diagram showing a molding method of the segment coil 30. The segment coil 30 is created by the procedure shown in FIGS. 6 (a) to 6 (e) using the twisting jig J. The twisting jig J is a cylindrical jig in which a recess is provided at a position corresponding to each of the first segment coil 30A and the second segment coil 30B. The depth of the recess is deeper at the position corresponding to the second segment coil 30B than at the position corresponding to the first segment coil 30A.

In FIG. 6, two second segment coils 30B are formed in the upper part of the drawing, and the first segment coil 30A is formed in all of the other parts in the upper part and the lower part in the drawing. Further, in the following, the rod-shaped first segment coil 30A that becomes the first segment coil 30A by being molded is referred to as a “rod-shaped first segment coil” 130A. Similarly, the rod-shaped second segment coil 30B that becomes the second segment coil 30B by being molded is referred to as a "rod-shaped second segment coil" 130B.

First, in the insertion step, the rod-shaped segment coil 30 is inserted into the stator core 20. FIG. 6A shows a state in which the insertion step is completed. The rod-shaped second segment coil 130B is longer than the rod-shaped first segment coil 130A. In the next initial position adjustment step, the twisting jig at the upper part of the drawing is moved in the direction indicated by reference numeral F1 in FIG. 6A. Specifically, in the initial position adjustment step, the twisting jig J is brought closer to the end face of the stator core 20 from a distance in the axial direction of the stator core 20, and only the tip of the rod-shaped second segment coil 130B is recessed in the twisting jig J. Adjust to the position where it will be inserted into. FIG. 6B shows a state in which the initial position adjustment step is completed.

In the next initial twisting step, as shown by reference numeral F2 in FIG. 6B, the relative positions of the stator core 20 and the twisting jig J are shifted by a predetermined amount in the circumferential direction, that is, twisted to form a rod-shaped second segment. The coil 130B is slightly deformed. FIG. 6 (c) shows a state in which the first twisting step is completed. In the next final position adjustment step, as shown by reference numerals F3 and F4 in FIG. 6B, the twisting jig J is brought closer to the end face of the stator core 20 from a distance in the axial direction of the stator core 20 to form a rod. Not only the two-segment coil 130B but also the tip of the rod-shaped first segment coil 130A is adjusted to the position where it is inserted into the recess of the twisting jig J. FIG. 6D shows a state in which the final position adjustment step is completed.

In the final final twisting step, as shown by reference numerals F5 and F6 in FIG. 6D, the relative positions of the stator core 20 and the twisting jig J are shifted by a predetermined amount in the circumferential direction, that is, twisted. As a result, the rod-shaped first segment coil 130A and the rod-shaped second segment coil 130B are deformed to form the first segment coil 30A and the second segment coil 30B. The segment coil 30 is formed by the above processing.

According to the first embodiment described above, the following effects can be obtained.
(1) The stator 100 is used for a rotary electric machine. The stator 100 includes a cylindrical stator core 20 in which a plurality of slots 21 are formed, and a plurality of segment coils 30 inserted into the slots 21 in layers along the radial direction of the stator core 20. .. At one end of the stator core 20, the segment coil 30 faces the stator core 20 between the connection portion 31 connected to the other segment coil 30 and the insertion portion 32 arranged inside the stator core 20. The first bent portion 34 to be bent, the second bent portion 35 which is a bent portion formed on the side closest to the connecting portion 31, and the oblique portion between the first bent portion 34 and the second bent portion 35. 33, is formed. The stator 100 includes a first segment coil 30A located on a predetermined layer of the layers and a second segment coil 30B located on the same layer as the first segment coil 30A. As shown in FIG. 5, the distance from the end face of the stator core 20 in the second segment coil 30B to the second bent portion 35 is from the end face of the stator core 20 in the first segment coil 30A to the second bent portion 35. It is Y which is the same as the distance of. The length of the skew portion 33 in the second segment coil 30B is different from the length of the skew portion 33 in the first segment coil 30A. Therefore, a plurality of segment coils 30 having different twist amounts T can be manufactured in one step, and productivity can be improved.

(2) The slanted portion 33 of the second segment coil 30B is formed longer than the slanted portion 33 of the first segment coil 30A. The length between the second bent portion 35 and the connecting portion 31 in the second segment coil 30B is formed longer than the length between the second bent portion and the connecting portion in the first segment coil. Therefore, it is not necessary to process only the tip portion of the second segment coil 30B, and the segment coil 30 can be molded with only one twisting jig J.

(3) The first segment coil 30A is connected to the segment coil 30 arranged in the adjacent layer. The second segment coil 30B constitutes a neutral wire by being connected to another segment coil 30 via the connecting member C. Therefore, since the position of the connecting portion 31 of the second segment coil 30B can be adjusted according to the shape of the neutral wire to be connected, the degree of freedom in designing the shape of the neutral wire is increased.

(4) The layer to which the first segment coil 30A and the second segment coil 30B belong is at least one layer of the innermost peripheral layer and the outermost outer peripheral layer of the stator 100. Therefore, since the connecting portion 31 is located on the innermost circumference or the outermost circumference, there is a margin of space, welding of the connecting portion 31 is facilitated, and the coil end can be kept low.

(5) The number of the second segment coil 30B is smaller than that of the first segment coil 30A. The second segment coil 30B is formed so that the length between the second bent portion 35 and the connecting portion 31 is longer than the length between the second bent portion 35 and the connecting portion 31 of the first segment coil 30A. Therefore, the number of segment coils 30 in which the second segment coil 30B is first inserted into the twisting jig J is small, and the productivity is improved. If the number of the second segment coil 30B is larger than that of the first segment coil 30A, more than half of the ends of the segment coil 30 will be inserted into the groove of the twisting jig J in the initial position adjustment step. Therefore, selection is complicated and inefficient.

(6) The method for manufacturing the stator 100 includes the following first to fourth steps. The first step is the above-mentioned insertion step, in which the first segment coil 30A and the second segment coil 30B having a longer axial length of the stator core 20 than the first segment coil 30A are inserted into the slot 21. Is. The second step is the above-mentioned initial position adjustment step, which is a step of bringing the twisting jig J into contact with the second segment coil 30B. The third step is the first twisting step described above, and is a step of tilting the second segment coil 30B in the circumferential direction of the stator core 20 by moving the twisting jig J in the circumferential direction of the stator core 20. The fourth step is the final position adjustment step described above, and by moving the twisting jig J in the axial direction of the stator core 20, the first segment coil 30A is used as the twisting jig J in addition to the second segment coil 30B. This is the process of contacting. The fourth step is the final twisting step described above, and is a step of tilting the first segment coil 30A and the second segment coil 30B in the circumferential direction by moving the twisting jig J in the circumferential direction. Therefore, the segment coil 30 can be formed in one step by appropriately moving the twisting jig J.

(Modification 1)
In the above-described embodiment, the second segment coil 30B has a longer skew portion length 33L than the first segment coil 30A, and the distance from the second bending portion 35 to the connection portion 31 is longer. However, the second segment coil 30B may have a shorter oblique portion length 33L than the first segment coil 30A, and the distance from the second bent portion 35 to the connecting portion 31 may be shorter.

(Modification 2)
The tip of the rod-shaped second segment coil 130B may be bent in advance and then inserted into the slot 21 to execute the final position adjusting step and the final twisting step without going through the initial position adjusting step and the initial twisting step.

(Modification 3)
In the above-described embodiment, the twist amount T of the first segment coil 30A, that is, the standard twist amount Ts is 2.5 slot pitch, and the twist amount T of the second segment coil 30B, that is, the excess twist amount Tt is 3.0 slot pitch. Illustrated as. By connecting the two first segment coils 30A, one of the slots 21 goes in and out of the other slot 21, so that the standard twist amount Ts is a multiple of 0.5 slot pitch. However, the excess twist amount Tt does not have to be a multiple of 0.5 slot pitch because only one end is inserted into the slot 21 especially when it is set at the end.

-Second embodiment-
The second embodiment of the stator of the rotary electric machine and the method of manufacturing the stator of the rotary electric machine will be described with reference to FIG. 7. In the following description, the same components as those in the first embodiment are designated by the same reference numerals, and the differences will be mainly described. The points not particularly described are the same as those in the first embodiment. This embodiment differs from the first embodiment mainly in that another variation in the shape of the segment coil is added.

FIG. 7 is a diagram showing a segment coil 30 in the second embodiment. In the present embodiment, the segment coil 30 includes a third segment coil 30C. The twist amount T and the length of the skew portion 33 of the third segment coil 30C are longer than those of the second segment coil 30B. That is, the twist amount T and the skew portion length 33L become longer in the order of the first segment coil 30A, the second segment coil 30B, and the third segment coil 30C. The distance from the end face of the stator core 20 to the second bent portion 35 is the same for all of the first segment coil 30A, the second segment coil 30B, and the third segment coil 30C. As shown in FIG. 7, the second segment coil 30B is arranged between the first segment coil 30A and the third segment coil 30C.

(Production method)
Hereinafter, the rod-shaped third segment coil 30C that becomes the third segment coil 30C by being molded is referred to as a “rod-shaped third segment coil” 130C. The rod-shaped third segment coil 130C is shorter than the rod-shaped second segment coil 130B and longer than the rod-shaped first segment coil 130A. Hereinafter, the differences from the manufacturing method in the first embodiment will be mainly described. The method for manufacturing the segment coil 30 in the present embodiment is significantly different from the first embodiment in that a second position adjusting step and a second twisting step are included between the first twisting step and the final position adjusting step.

The twisting jig J2 used in the present embodiment is a cylindrical jig having recesses at positions corresponding to the first segment coil 30A, the second segment coil 30B, and the third segment coil 30C, respectively. As shown in FIG. 7, the depth of the recess of the twisting jig J2 is deeper at the position corresponding to the third segment coil 30C than at the position corresponding to the first segment coil 30A, and corresponds to the second segment coil 30B. The position to do is the deepest.

First, in the insertion step, all the rod-shaped segment coils 30 are inserted into the stator core 20. The rod-shaped segment coil 30 inserted at this time is different from the first embodiment in that the rod-shaped third segment coil 130C is included. The initial position adjustment step and the initial twisting step are the same as those in the first embodiment. That is, in the first twisting step, only the longest rod-shaped second segment coil 130B is machined.

In the second position adjustment step, the twisting jig J is brought closer to the end face of the stator core 20 from a distance in the axial direction of the stator core 20, and the tip of the rod-shaped third segment coil 130C is twisted in addition to the rod-shaped second segment coil 130B. Adjust the position so that it is inserted into the recess of the jig J. In the subsequent second twisting step, the relative positions of the stator core 20 and the twisting jig J are shifted by a predetermined amount in the circumferential direction, that is, twisted to deform the rod-shaped second segment coil 130B and the rod-shaped third segment coil 130C.

The next final position adjustment step is the same as that of the first embodiment. Adjust the tip to the position where it is inserted into the recess of the twisting jig J. The final final twisting step is the same as that of the first embodiment, and the relative positions of the stator core 20 and the twisting jig J are shifted by a predetermined amount in the circumferential direction, that is, the shapes of all the segment coils 30 are formed by twisting. To process.

According to the second embodiment described above, the following effects can be obtained.
(7) A third segment coil 30C having an oblique portion 33 longer than the oblique portion 33 in the second segment coil 20B is provided. In a predetermined layer, the second segment coil 30B is arranged between the first segment coil 30A and the third segment coil 30C. Therefore, even if the variation of the segment coil 30 is increased, the segment coil 30 can be molded in one step as in the first embodiment.

The above-mentioned embodiments and modifications may be combined. Although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other aspects considered within the scope of the technical idea of the present invention are also included within the scope of the present invention.

20 ... Stator core 21 ... Slot 30 ... Segment coil 30A ... First segment coil 30B ... Second segment coil 30C ... Third segment coil 130A ... Rod-shaped first segment coil 130B ... Rod-shaped second segment coil 130C ... Rod-shaped third segment Coil 31 ... Connection part 32 ... Insertion part 33 ... Oblique part 33L ... Oblique part length 34 ... First bending part 35 ... Second bending part 100 ... Stator C ... Connecting members J, J2 ... Twisting jig

Claims

A stator of a rotary electric machine including a cylindrical stator core in which a plurality of slots are formed, and a plurality of segment coils inserted into the slots in layers along the radial direction of the stator core. ,
At one end of the stator core, the segment coil is located between a connection portion connected to another segment coil and an insertion portion arranged inside the stator core.
The first bending portion that bends toward the stator core,
The second bent portion formed on the side closest to the connecting portion,
And an oblique portion between the first bent portion and the second bent portion is formed.
A first segment coil located in a predetermined layer among the layers, and
Includes a second segment coil located on the same layer as the first segment coil.
The distance from the end face of the stator core in the second segment coil to the second bent portion is the same as the distance from the end face of the stator core in the first segment coil to the second bent portion.
A stator of a rotary electric machine in which the length of the skew portion in the second segment coil is different from the length of the skew portion in the first segment coil.
The stator of the rotary electric machine according to claim 1.
The skewed portion of the second segment coil is formed longer than the skewed portion of the first segment coil.
A rotary electric machine in which the length between the second bent portion and the connecting portion in the second segment coil is formed longer than the length between the second bent portion and the connecting portion in the first segment coil. Stator.
The stator of the rotary electric machine according to claim 2.
The first segment coil is connected to the segment coil arranged in the adjacent layer.
The second segment coil is a stator of a rotary electric machine that constitutes a neutral wire by being connected to another segment coil via a connecting member.
The stator of the rotary electric machine according to claim 3, wherein the stator
Further comprising a third segment coil having the skew portion longer than the skew portion in the second segment coil.
In the predetermined layer, the second segment coil is a stator of a rotary electric machine arranged between the first segment coil and the third segment coil.
The stator of the rotary electric machine according to claim 3, wherein the stator
The predetermined layer is a stator of a rotary electric machine, which is at least one layer of the innermost layer and the outermost layer of the stator.
The stator of the rotary electric machine according to claim 1.
The number of the second segment coil is smaller than that of the first segment coil.
A stator of a rotary electric machine in which the length between the second bent portion and the connection portion is formed longer than the length between the second bending portion and the connection portion of the first segment coil.
A method for manufacturing a stator of a rotary electric machine, comprising a stator core in which a plurality of slots are formed, and a plurality of segment coils formed in layers along the radial direction of the stator core and inserted into the slots. hand,
The first step of inserting the first segment coil and the second segment coil in which the axial length of the rotary electric machine is formed larger than that of the first segment coil into the slot.
The second step of bringing the jig into contact with the second segment coil and
A third step of tilting the second segment coil in the circumferential direction of the stator core by moving the jig in the circumferential direction of the stator core.
A fourth step of bringing the first segment coil into contact with the jig in addition to the second segment coil by moving the jig in the axial direction of the stator core.
A method for manufacturing a stator of a rotary electric machine, comprising a fifth step of tilting the first segment coil and the second segment coil in the circumferential direction by moving the jig in the circumferential direction of the stator core.