JP2019180214A - motor - Google Patents

Abstract

To provide a motor that hardly produces shavings and has high stator rigidity by minimizing an influence of contacting between a stator and a housing on magnetic characteristics of the stator.SOLUTION: A stator core 120 has a plurality of core pieces 131 which are arrayed in a circumferential direction and an insert member 139 which are columnar magnetic bodies and held between adjacent core pieces. A core piece has a core back part 121 in an arcuate shape. An outer peripheral surface of the stator core is in contact with a housing 13. The stator core is provided with an inserted part 132a into which the insert member is inserted at a connection region between adjacent core back parts. The inserted part is a through hole extending along the center axis of the stator core or a groove which extends along the center axis and is open radially inside the core back parts. The insert member is held in contact with two core back parts adjacent in a circumferential direction at the inserted part.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a motor.

  2. Description of the Related Art Conventionally, an inner rotor type motor having a rotor that rotates about a central axis and a stator that surrounds the rotor from the outside in the radial direction is known. As a stator provided in an inner rotor type motor, a configuration in which a plurality of stator core blocks divided in the circumferential direction are integrated to form a cylindrical stator is known.

  In a stator configured by integrating a plurality of stator core blocks, a gap is generated between adjacent stator core blocks, and there is a possibility that magnetic characteristics may deteriorate between adjacent stator core blocks.

  Therefore, in Patent Document 1, after inserting a stator configured by integrating a plurality of stator core blocks into a cylindrical frame, a columnar wedge is inserted outside the stator in the radial direction, thereby adjacent stators. The contact parts between the iron core blocks are in close contact. Thereby, in the motor having the stator of Patent Document 1, the deterioration of the magnetic characteristics is suppressed, and the cogging torque is suppressed.

JP 2009-291003 A

  However, in the configuration of the motor of Patent Document 1, a columnar wedge is driven between the stator and the frame, and the stator and the frame are fixed by the driven wedge. In the stator of the motor having such a configuration, stress is concentrated on a specific portion where the wedge is driven.

  In this case, the stress concentrated on a specific portion outside the stator extends to the inside in the radial direction of the stator core block constituting the stator without being dispersed around the stator, and there is a risk of deteriorating the magnetic characteristics of the stator. .

  Further, in the configuration of the motor disclosed in Patent Document 1, when a columnar wedge is driven, there is a possibility that shavings may be generated due to friction between the wedge and the stator iron core block or the wedge and the frame. In the motor of Patent Document 1, a gap is easily left between the stator and the frame by driving a wedge between the stator and the frame. For this reason, when shavings are generated, the shavings do not stay between the stator and the frame and may move from between the stator and the frame to the inside of the stator. In this case, there is a possibility that the shavings may enter between the stator and the rotor and hinder the movement. In addition, the shavings may come into contact with the coil and cause a short circuit.

  The present invention has been made in view of such circumstances, minimizing the influence of the contact between the stator and the housing on the magnetic characteristics of the stator, making it difficult for shavings to occur, and the rigidity of the stator to be reduced. The object is to provide a high motor.

  In order to solve the above-described problems, according to one aspect of the present invention, a rotor that can rotate around a central axis, a stator that surrounds the rotor with a gap from the radial outer side of the rotor, and the stator are accommodated And the stator includes a coil and a stator core around which the coil is wound, and the stator core includes a plurality of core pieces arranged in a circumferential direction. An insertion member sandwiched between adjacent core pieces, and the core piece has a core back portion having an arc shape when viewed from the central axis direction, and an outer periphery of the stator core The surface is in contact with the housing, and the insertion member is inserted into a connection portion between the core back portions adjacent to each other in the circumferential direction in the stator core. An insertion portion is provided, and the insertion portion is a through hole extending in the direction of the central axis in the stator core or a groove extending in the direction of the central axis and opening radially inward of the core back portion, and the insertion member Provides a motor that is held in contact with the core back portions of the two core pieces adjacent in the circumferential direction in the inserted portion.

  According to the present invention, it is possible to provide a motor in which the influence of the contact between the stator and the housing on the magnetic characteristics of the stator is minimized, shavings are hardly generated, and the stator has high rigidity.

Drawing 1 is an exploded perspective view showing motor 1 of an embodiment. FIG. 2 is a plan view of the stator 12 accommodated in the housing 13. FIG. 3 is an explanatory diagram for explaining a method for manufacturing the motor 1. FIG. 4 is an explanatory view for explaining an insertion member held between the core pieces 131. FIG. 5 is an explanatory view for explaining the insertion member held between the core pieces 131. FIG. 6 is an explanatory diagram for explaining a method for manufacturing the motor 1. FIG. 7 is an explanatory view showing a modification of the core piece of the motor 1. FIG. 8 is an explanatory view showing a modification of the core piece of the motor 1.

  Hereinafter, the motor according to the present embodiment will be described with reference to FIGS.

  Each figure shows the Z-axis as appropriate. The Z-axis direction in each figure is a direction parallel to the axial direction of the central axis J shown in FIG. In the following description, the positive side (+ Z side, one side) in the Z-axis direction is referred to as “upper side”, and the negative side (−Z side, the other side) in the Z-axis direction is referred to as “lower side”. Call. The upper side and the lower side are directions used for explanation only, and do not limit the actual positional relationship and direction.

  Unless otherwise specified, the direction parallel to the central axis J (Z-axis direction) is simply referred to as “axial direction” or “vertical direction”, and the radial direction around the central axis J is simply referred to as “radial direction”. The circumferential direction around the central axis J, that is, the circumference of the central axis J is simply referred to as “circumferential direction”.

  In the following description, “plan view” means a state viewed from the axial direction.

  In the following description, the “plan view” means a view when seen in a plan view.

  Moreover, in the following drawings, in order to make each structure easy to understand, the actual structure may be different from the scale, number, or the like in each structure.

  FIG. 1 is an exploded perspective view showing a motor 1 of the present embodiment. In FIG. 1, a part of the configuration is omitted.

  As shown in FIG. 1, the motor 1 includes a rotor 11, a stator 12, and a housing 13.

(Rotor)
The rotor 11 includes a shaft 20 disposed along a central axis J extending in the vertical direction, and a bearing 15, a rotor core 18, and a bearing 16 arranged along the central axis on the shaft 20. The bearing 15, the rotor core 18, and the bearing 16 are arranged in this order from the lower side to the upper side.

  The shaft 20 is a columnar member extending in the axial direction. The shaft 20 is rotatably supported by the bearing 15 and the bearing 16.

  The rotor core 18 is fixed to the outer surface of the shaft 20. The rotor core 18 surrounds the shaft 20 in the circumferential direction. The rotor core 18 has a plurality of rotor magnets (not shown). In the rotor magnet, N poles and S poles are alternately arranged in the circumferential direction and fixed. The rotor core 18 rotates together with the shaft 20.

(Stator)
The stator 12 surrounds the rotor 11 with a gap from the radially outer side of the rotor 11.
The stator 12 includes a stator core 120 and a coil 123. In FIG. 1, only a part of the core back 121, the teeth 122, and the coil 123 is shown. Moreover, in FIG. 1, illustration of the structures with which a normal stator, such as an insulator and an insulating sheet, is omitted.
The stator 12 will be described in detail later.

  The stator core 120 includes a cylindrical core back 121 centered on the central axis J, and a plurality of teeth 122 extending radially inward from the core back 121 and arranged in the circumferential direction. The coil 123 is wound around the tooth 122.

  A plurality of concave grooves 125 extending along the central axis direction are provided in the outer peripheral surface of the stator 12, that is, the outer peripheral surface 121 x of the core back 121. The concave groove 125 is recessed inward in the radial direction. That is, the concave groove 125 is opened on the radially outer side, the upper side, and the lower side, respectively. The plurality of concave grooves 125 overlap each of the plurality of teeth 122 in a one-to-one manner when viewed from the radial direction.

  The concave groove 125 is used as a reference when the coil 123 is wound around the tooth 122, for example.

  The number of poles and the number of slots of the motor 1 are not limited to this embodiment, and are appropriately selected according to the required output and the winding method. The motor 1 in the present embodiment is a three-phase motor having 10 poles and 12 slots.

(housing)
The housing 13 accommodates the rotor 11 and the stator 12. The housing 13 surrounds the stator 12 from the outside in the radial direction and fixes the stator 12, a bracket 13b provided at the lower end of the cylindrical portion 13a, and an unillustrated provided at the upper end of the cylindrical portion 13a. And a flange.

  A bearing holder 140 is provided on the bracket 13b. The bearing holder 140 holds the bearing 15.

  A through hole 141 is provided in the central portion of the bracket 13b in plan view. The lower end of the shaft 20 is inserted into the through hole 141. The lower end of the shaft 20 protrudes from the through hole 141 to the outside of the housing 13.

  A bearing holder (not shown) is provided inside the housing 13 on the upper side of the stator 12. The bearing holder holds the bearing 16.

FIG. 2 is a plan view of the stator 12 accommodated in the housing 13.
The stator 12 is fixed to the housing 13 with an interference fit. The interference fit may be press fit or shrink fit. The outer peripheral surface 121 x of the stator 12 is in contact with the inner peripheral surface 13 x of the housing 13.

  The stator core 120 has a plurality of core pieces 131 arranged in the circumferential direction and a plurality of insertion members 139 sandwiched between adjacent core pieces 131.

  The core piece 131 includes a core back portion 132 that has an arc shape in plan view, and a tooth 122 that extends radially inward from the core back portion 132.

  The core piece 131 is a laminated body in which a plurality of electromagnetic steel plates punched out in a plan view of the core piece 131 are laminated in the axial direction.

  In the stator core 120, an insertion portion 132 a into which the insertion member 139 is inserted is provided at a connection site A between the core back portions 132 adjacent in the circumferential direction. In the stator core 120 shown in the drawing, the end portions of the core back portion 132 facing each other at the connection site A are provided with recess portions 132b that are recessed in the circumferential direction. The inserted portion 132a is integrally formed.

  In addition, the concave stripe part 132b is good also as being provided only in either one of the adjacent core back parts 132. FIG. In this case, a portion surrounded by the concave stripe portion 132b provided in one core back portion 132 and the end portion of the other core back portion 132 is an inserted portion.

The inserted portion 132 a is a through-hole extending in the axial direction in the stator core 120 or a groove extending in the axial direction and opening in the radial inner side of the core back portion 132, that is, the inner peripheral surface 121 y of the core back 121. The inserted portion 132a is preferably a groove.
In the drawing, the inserted portion 132a is shown as a groove.

  The insertion member 139 is a columnar magnetic body. The circumferential width of the insertion member 139 is larger than the circumferential width of the inserted portion 132a.

  The radially inner surface 139a of the insertion member 139 inserted into the groove-like inserted portion 132a is continuous with the inner peripheral surface 121y of the core back 121 without a step, or has a diameter larger than the inner peripheral surface 121y of the core back 121. It is preferable that it protrudes inward in the direction.

  The inserted portions 132a are provided in all the connection portions A of the stator core 120, respectively. The plurality of insertion members 139 are inserted into all the inserted portions 132a. The insertion members 139 are respectively held in contact with the core back portions 132 of the two core pieces 131 adjacent in the circumferential direction in the inserted portion 132a.

Next, a method for manufacturing the motor 1 will be described.
First, as shown in FIG. 3, a plurality of plate members 150 having the same shape as the plan view shape of the stator core 120 are manufactured from the base material 1000 of the electromagnetic steel plate. The plate member 150 is further divided into a plurality of plate members 151 having the same shape as the plan view of the core piece 131. The core piece 131 is manufactured by laminating a plurality of plate members 151 in the axial direction.

  As described above, the stator core 120 is manufactured by arranging the obtained core pieces 131 in the circumferential direction.

  Here, when the stator core 120 is manufactured using the manufactured core piece 131, the plurality of core pieces 131 can be arranged in the circumferential direction while matching the rolling direction of the plate material 151 included in each of the plurality of core pieces 131. preferable.

  By arranging the plurality of plate members 151 so as to restore the original plate member 150, the growth directions of the metal structures of the adjacent plate members 151 coincide with each other, and it is difficult for magnetic flux disturbance to occur between the plate members 151.

  Here, the structure of the base material 1000 is stretched in the rolling direction α of the base material. Therefore, even if the plurality of plate materials 151 have the same shape, the growth directions of the metal structures of the plate materials 151 are matched as described above by matching the rolling directions of the respective plate materials 151, and between the plate materials 151. This makes it difficult to disturb the magnetic flux.

  The rolling direction of the plate material 151 can be observed visually or with a microscope. Specifically, the rolling direction of the plate material 151 can be confirmed by observing the surface of the plate material 151. That is, when the surface of the plate 151 is observed, a plurality of streak lines extend in the same direction. The direction parallel to the direction in which the streak line extends is the rolling direction.

  Further, when the core piece 131 is manufactured by laminating a plurality of plate materials 151, it is preferable to collect and laminate the plate materials 151 having the same rolling direction α among the plurality of plate materials 151 made from the plurality of plate materials 150.

  4 and 5 are explanatory views for explaining an insertion member sandwiched between the core pieces 131.

  As shown in FIG. 4, the insertion member 139 </ b> A may be a laminate in which a plurality of plate materials 152 manufactured from a base material of an electromagnetic steel plate are laminated in the axial direction. The plate member 152 has the same shape as the plan view shape of the insertion member 139A.

  As shown in FIG. 4, such an insertion member 139A is a laminated body of electromagnetic steel plates like the core piece 131A and the core piece 131B sandwiching the insertion member 139A, so that the growth direction of the metal structure in the electromagnetic steel plates is the same in-plane direction It becomes. Therefore, magnetic flux disturbance is less likely to occur at the interface between the core piece 131A and the insertion member 139A and at the interface between the core piece 131B and the insertion member 139A.

Moreover, as shown in FIG. 5, the insertion member 139B may be a columnar single member.
Such an insertion member 139B is preferable because it is sandwiched between the core piece 131A and the core piece 131B and is not easily damaged even when tightened with a high pressure.
As shown in FIGS. 4 and 5, in the motor 1 of the present embodiment, the insertion member 139 is sandwiched between the adjacent core piece 131 </ b> A and core piece 131 </ b> B during assembly, and is sandwiched in contact with each other. Therefore, compared with the case where the insertion member 139 is driven in the axial direction, when the insertion member 139 is inserted into the inserted portion 132a, internal stress due to axial friction between the insertion member 139 and the core piece is less likely to occur, and the obtained stator core Degradation of magnetic properties can be suppressed.

  Next, as shown in FIG. 6, the coil 123 is wound around the teeth 122 included in each core piece 131. The coil 123 is wound around the tooth 122 by so-called concentrated winding.

  In the motor of the present embodiment, since the stator core 120 is divided into the plurality of core pieces 131, the operation of winding the coil 123 around the teeth 122 is easier than in the case of an integral core in which the stator core is not divided in the circumferential direction. Thereby, many coils 123 can be wound around the teeth 122, and a space factor can be raised.

  Next, a plurality of core pieces 131 in which the coil 123 is wound around the teeth 122 are arranged in the circumferential direction. Further, the insertion member 139 is inserted into the inserted portion 132 a provided in the adjacent core back portion 132, and the whole is tightened from the radially outer surface of the core piece 131.

  As described above, the circumferential width of the insertion member 139 is larger than the circumferential width of the inserted portion 132a. Therefore, the insertion member 139 contacts the adjacent core back part 132 in a state having internal stress.

  Next, the adjacent core pieces 131 are welded and fixed to each other on the radially outer surface 132x of the core back portion 132, so that the stator core 120 is obtained. In the figure, the welding location is indicated by the symbol X.

  Thereafter, as shown in FIG. 2, the obtained stator core 120 is inserted into the housing 13 by press fitting or shrink fitting and fixed.

  When the stator core 120 is press-fitted into the housing 13 and fixed, the stator core 120 and the housing 13 may be rubbed to generate shavings. Therefore, when press-fitting the stator core 120, an adhesive may be applied to the outer peripheral surface of the stator core 120. The adhesive applied to the outer peripheral surface of the stator core 120 captures the generated shavings and holds the shavings between the stator core 120 and the housing 13. Thereby, malfunctions, such as a lock | rock and a short circuit which arise due to shavings, can be suppressed.

  When the stator core 120 is fixed to the housing 13 by shrink fitting, it is preferable because the stator core 120 and the housing 13 are not easily rubbed and shavings are not easily generated.

  As shown in FIG. 2, the outer peripheral surface of the stator core 120 is in close contact with the inner peripheral surface 13 x of the housing 13 over the entire periphery in plan view. Therefore, the internal stress generated in the stator core 120 due to press fitting or shrink fitting is distributed over the entire contact surface between the stator core 120 and the housing 13. In such a configuration, internal stress generated on the outer peripheral surface of the stator core 120 is difficult to reach the inner peripheral surface of the stator core 120, and adverse effects on magnetic properties can be suppressed.

  In addition, the motor 1 can be manufactured by assembling the rotor 11 and the like.

  As described above, in a stator configured by integrating a plurality of core pieces, there is a possibility that a gap is generated between adjacent core pieces, and the magnetic characteristics are deteriorated between the adjacent core pieces. If the magnetic characteristics of the stator deteriorate, the cogging torque may increase.

  On the other hand, in the motor 1 of this embodiment, the outer peripheral surface of the stator core 120 is fixed by the housing 13 and further welded. Therefore, in the motor 1, it is difficult for a gap to be generated between the adjacent core pieces 131 on the outer peripheral surface 121 x side of the stator core 120.

  In addition, on the inner peripheral surface side of the stator core 120, the insertion member 139 that is a magnetic body is held in contact with the core back portion 132 of the adjacent core piece 131. Therefore, in the stator core 120, the magnetic characteristics are improved as compared with the stator core that does not have the insertion member 139, and the magnetic flux generated by the coil 123 wound around the teeth 122 is favorably generated on the inner peripheral surface side of the stator core 120.

  Further, the stress that the stator core 120 receives from the housing 13 is distributed over the entire outer peripheral surface without being concentrated on a specific portion on the outer peripheral surface of the stator core 120. Therefore, the stress generated on the outer peripheral surface of the stator core 120 is difficult to reach the inner peripheral surface of the stator core 120, and a decrease in magnetic characteristics can be suppressed.

  Therefore, according to the motor 1 of the present embodiment, the influence of the contact between the stator and the housing on the magnetic characteristics of the stator is minimized, the shavings are hardly generated, and the stator has high rigidity.

  In the present embodiment, the stator core 120 is obtained using the plurality of core pieces 131 and the plurality of insertion members 139, but the configuration of the core piece 131 is not limited to the configuration shown in the figure.

  7 and 8 are explanatory views showing a modification of the core piece included in the motor of the present embodiment.

  First, as shown in a partially enlarged view of FIG. 7, the stator core 126 has a plurality of core pieces 133 arranged in the circumferential direction and a plurality of insertion members 139 sandwiched between adjacent core pieces 133.

  The core piece 133 includes a core back portion 134 that has an arc shape in plan view, and teeth 122 that extend radially inward from the core back portion 134.

A concave portion 134a that is recessed in the circumferential direction is provided at one of the ends of the pair of core back portions 134 that face each other at the connection portion A of the stator core 126.
The other end of the pair of core back portions 134 is provided with a convex portion 134b that protrudes in the circumferential direction and that fits complementarily with the concave portion 134a.

  The core pieces 133 having such a configuration are easy to fasten the core pieces 133 together. Further, when assembling the stator core 126 by arranging a plurality of core pieces 133 in the circumferential direction, the core pieces 133 are not easily displaced in the radial direction, and assembly is facilitated.

  The core piece 133 as shown in FIG. 7 is a laminated body in which a plurality of electromagnetic steel sheets punched out in a plan view shape of the core piece 133 are laminated in the axial direction. Such a core piece 133 is obtained by first punching an electromagnetic steel plate into the shape of the stator core 126 in plan view, then dividing the obtained plate material into the shape of each core piece 133, and stacking the obtained plate material in the axial direction. It is preferable to manufacture it.

  Generally, the punching process of the electromagnetic steel sheet is performed using a press die. In this case, the size of the obtained plate material may slightly change due to wear of the mold. Therefore, if the laminated bodies that are laminated after individually punching the plate members in a plan view of the core pieces are arranged in the circumferential direction, due to a slight deviation in the size of the plate members, There may be gaps or steps.

  On the other hand, as described above, when the shape of the stator core 126 is first punched out from the base material of the electromagnetic steel sheet and then divided into the shape of the core piece 133, the size of the obtained plate material has an influence on the wear of the mold. It is hard to receive and is preferable. When the core piece 133 manufactured in this way is used, the assembly accuracy is improved.

  Here, when the size of the plate material in the shape of the stator core 126 is compared with the size when the plate material in the shape of the core piece 133 obtained by the above method is arranged in the circumferential direction, the cut in which the plate material in the shape of the stator core 126 is divided. The core piece 133 may be smaller by the width of the portion. Further, when the core piece 133 is manufactured by the above method, it is difficult to enlarge the size of the core piece 133 in the circumferential direction.

  On the other hand, in the motor 1 of this embodiment, the insertion member 139 is clamped by the core piece 133, so that the gap between the core pieces 133 can be eliminated and the deterioration of the magnetic characteristics can be suppressed. Therefore, even if the core piece 133 obtained by the above method is used, a good motor can be obtained.

  Also, the plurality of core pieces 135 shown in FIG. 8 constitutes a straight core 127 that is connected to the adjacent core pieces 135 in the core back portion 136 in a band shape in the circumferential direction. The plurality of core pieces 135 are connected by a connecting portion 137 in the core back portion 136.

  When the stator is obtained using the straight core 127, it is preferable that the core pieces 135 positioned at both ends in the circumferential direction of the straight core 127 are welded to the radially outer surface of the core back portion 136.

  In the straight core 127 having such a configuration, a gap is easily formed between adjacent core pieces 135, and the magnetic characteristics are easily deteriorated. However, as in the present embodiment, the stator core is configured by inserting the above-described insertion member into the inserted portion 136a provided in the core back portion 136, thereby improving the magnetic characteristics and suppressing the cogging torque. Become.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to such examples. For example, the inserted portion may not be provided between all adjacent core pieces. In the case of a three-phase motor, even if the stator core has a configuration in which inserted portions are provided at three locations to be pointed about the central axis J, and the insertion member 139 is inserted into the three inserted portions. Good. In such a configuration, the cogging torque is suppressed.

  Further, the shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Motor, 11 ... Rotor, 12 ... Stator, 13 ... Housing, 120, 126 ... Stator core, 121 ... Core back, 123 ... Coil, 127 ... Straight core, 131, 131A, 131B, 133, 135 ... Core piece, 132, 134,136 ... core back part, 132a, 136a ... inserted part, 132b ... concave line part, 132x, 139a ... surface, 134a ... concave part, 134b ... convex part, 139, 139A, 139B ... insertion member, 1000 ... base material A: Connection site, J: central axis, α: rolling direction

Claims (12)

A rotor rotatable about a central axis;
A stator surrounding the rotor with a gap from the outside in the radial direction of the rotor;
A housing for accommodating and fixing the stator,
The stator includes a coil;
A stator core having teeth, and the coil wound around the teeth,
The stator core includes a plurality of core pieces arranged in a circumferential direction;
An insertion member that is a columnar magnetic body and is sandwiched between adjacent core pieces,
The core piece has a core back portion having an arc shape when viewed from the central axis direction,
An outer peripheral surface of the stator core is in contact with the housing;
In the stator core, an insertion portion into which the insertion member is inserted is provided at a connection portion between the core back portions adjacent in the circumferential direction.
The inserted portion is a through-hole extending in the direction of the central axis in the stator core or a groove extending in the direction of the central axis and opening radially inward of the core back portion;
The motor in which the insertion member is held in contact with the core back portions of the two core pieces adjacent to each other in the circumferential direction in the insertion portion. In each of the end portions of the pair of core back portions facing each other at the connection site, a concave strip portion that is recessed in the circumferential direction is provided,
The motor according to claim 1, wherein the pair of concave portions are integrated to form the inserted portion.   The motor according to claim 1, wherein the core piece and the insertion member are a laminated body in which electromagnetic steel plates are laminated in the direction of the central axis. The core piece is a laminate in which electromagnetic steel sheets are laminated in the direction of the central axis,
The motor according to claim 1, wherein the insertion member is a columnar single member. The core piece is a laminate in which electromagnetic steel sheets are laminated in the direction of the central axis,
The motor according to any one of claims 1 to 4, wherein the stator core has a rolling direction of the electromagnetic steel sheet included in each of the plurality of core pieces. In the connection part, a concave portion that is recessed in the circumferential direction is provided at one end portion of the pair of end portions facing each other, the core back portions,
The motor according to claim 1, wherein a convex portion that protrudes in the circumferential direction and fits into the concave portion is provided at the other end portion of the pair of end portions.   The motor according to claim 1, wherein the adjacent core pieces are welded to each other at a radially outer surface of the core back portion.   5. The motor according to claim 1, wherein the plurality of core pieces are straight cores connected in a band shape in the circumferential direction at the core back portion.   The motor according to claim 8, wherein the core pieces positioned at both ends of the straight core in the circumferential direction are welded to the radially outer surface of the core back portion.   The motor according to any one of claims 1 to 9, wherein the stator is fixed to the housing by an interference fit. A plurality of the insertion members;
In the stator core, the inserted portions are provided in all the connection parts,
The motor according to any one of claims 1 to 10, wherein the insertion member is inserted into all the inserted portions. The motor is a three-phase motor,
Three insertion members,
In the stator core, the inserted portion is provided at three points to be pointed around the central axis,
The motor according to any one of claims 1 to 10, wherein the insertion member is inserted into the inserted portion at three locations.

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