Stator, motor, and method for manufacturing stator

Abstract

One embodiment of a stator according to the present invention is a stator that faces a rotor that can rotate around a central axis line in the axial direction, the stator being provided with: a plurality of teeth arranged in the circumferential direction; coils respectively attached to the plurality of teeth; and a first resin part for holding the plurality of teeth. The first resin part has an insulator part positioned between the teeth and the coils.

Description

Stator, motor, and method for manufacturing the stator

[0001] This application is based on Japanese Patent Application No. 2024-001884, filed on January 10, 2024. This application claims the benefit of priority to that application, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a stator, a motor, and a method for manufacturing a stator.

[0003] Axial gap motors, in which a rotor and a stator face each other in the axial direction, have advantages such as light weight and high torque density. Japanese Patent Laid-Open Publication No. 2015-180150 discloses an axial gap motor having multiple stator cores formed by insert-molding a core body made of multiple steel plates inside a bobbin.

[0004] Japanese Patent Publication No. 2015-180150

[0005] In conventional axial gap motors, multiple stator cores had to be separately connected and arranged in a circular ring shape, which made the manufacturing process complicated.

[0006] The present invention has been made in view of the above-mentioned problems, and one of its objects is to provide a stator, a motor, and a method for manufacturing a stator that can simplify the manufacturing process.

[0007] One aspect of the stator of the present invention is a stator that faces a rotor rotatable about a central axis in an axial direction, and includes a plurality of teeth arranged in a circumferential direction, coils attached to the plurality of teeth, respectively, and a first resin portion that holds the plurality of teeth. The first resin portion has an insulator portion located between the teeth and the coils.

[0008] One aspect of the motor of the present invention includes the stator and the rotor.

[0009] One aspect of the method for manufacturing a stator of the present invention is a method for manufacturing a stator that axially faces a rotor that is rotatable around a central axis, and includes an arrangement step of arranging multiple teeth in a cavity of a mold, a molding step of filling the cavity with resin to mold a first resin part, forming insulator parts on the surfaces of the teeth, and holding the multiple teeth with the first resin part, and an attachment step of attaching coils to the teeth via the insulator parts.

[0010] According to one aspect of the present invention, it is possible to provide a stator, a motor, and a method for manufacturing a stator that can simplify the manufacturing process.

[0011] FIG. 1 is an exploded perspective view of a motor according to the first embodiment. FIG. 2 is a cross-sectional view of the motor according to the first embodiment. FIG. 3 is a perspective view showing multiple teeth according to the first embodiment. FIG. 4 is a perspective view of multiple teeth and a first resin portion according to the first embodiment. FIG. 5 is a partially enlarged view of FIG. 4. FIG. 6 is a schematic cross-sectional view of a mold for molding the first resin portion according to the first embodiment. FIG. 7 is a cross-sectional view of the mold along the radial direction taken along line VII-VII in FIG. 6. FIG. 8 is a perspective view of a molded part according to the first embodiment to which a coil and a bus bar are attached. FIG. 9 is a perspective view of a molded part according to the first embodiment to which a coil, a bus bar, and a shaft are attached. FIG. 10 is a perspective view of a molded part according to the first embodiment to which each component is attached and which is filled with a second resin portion. FIG. 11 is a perspective view of multiple U-phase coils according to the first embodiment. FIG. 12 is a perspective view of multiple V-phase coils according to the first embodiment. FIG. 13 is a perspective view of multiple W-phase coils according to the first embodiment. FIG. 14 is a schematic diagram showing a steel plate cutting process for a modified example of the first embodiment. FIG. 15 is a perspective view of a tooth for a modified example of the first embodiment. FIG. 16 is a perspective view of a stator for a second embodiment. FIG. 17 is a perspective view of the stator for the second embodiment with the second resin portion omitted. FIG. 18 is a perspective view of a motor for a third embodiment. FIG. 19 is a perspective view of a molded part for a third embodiment. FIG. 20 is an exploded perspective view of a plurality of teeth and a back yoke for the third embodiment. FIG. 21 is a schematic cross-sectional view of a mold for molding the first resin portion for the third embodiment. FIG. 22 is a side view of an electric motorcycle having a motor for any of the embodiments. FIG. 23 is a perspective view of an unmanned aerial vehicle having a motor for any of the embodiments. FIG. 24 is a schematic view of an electric power steering device having a motor for any of the embodiments.

[0012] Motors according to embodiments of the present invention will be described below with reference to the drawings. Note that the scope of the present invention is not limited to the following embodiments and can be modified as desired within the scope of the technical concept of the present invention. A Z-axis is shown in each figure as appropriate. The Z-axis is an imaginary axis parallel to the central axis J, which will be described later. The Z-axis is also an up-down direction, with the positive side being the "upper side" and the negative side being the "lower side." However, the orientation of the motor relative to the up-down direction in this specification is an example for the purpose of explanation and does not limit the orientation of the motor when in use.

[0013] [First embodiment] Fig. 1 is an exploded perspective view of a motor 1 according to a first embodiment. Fig. 2 is a cross-sectional view of the motor 1 according to the first embodiment.

[0014] As shown in FIG. 1 , the motor 1 of this embodiment has a pair of rotors 10 and 20 and a stator 60 disposed between the pair of rotors 10 and 20 .

[0015] The stator 60 of this embodiment faces the rotors 10 and 20 in the axial direction with a gap therebetween. The motor 1 of this embodiment is a single-stator, double-rotor axial gap motor. The motor 1 of this embodiment is also a three-phase AC motor.

[0016] <Rotor> The pair of rotors 10, 20 are rotatable about a central axis J. In this specification, the central axis J is an imaginary line extending in the vertical direction. In the following description, the axial direction of the central axis J may be simply referred to as the "axial direction," the direction corresponding to the lower side of the axial direction may be simply referred to as the "one axial side," and the direction corresponding to the upper side may be simply referred to as the "other axial side." Furthermore, in the following description, the radial direction centered on the central axis J may be simply referred to as the "radial direction," and the circumferential direction centered on the central axis J may be simply referred to as the "circumferential direction."

[0017] 2, one of the pair of rotors 10, 20 is located above the stator 60, and the other is located below the stator 60. The pair of rotors 10, 20 rotate synchronously around the central axis J. According to this embodiment, by sandwiching the stator 60 between the pair of rotors 10, 20 from both sides in the axial direction, it is possible to effectively utilize the magnetic flux above and below the stator 60, thereby providing a motor 1 with high torque and high efficiency.

[0018] In the following description, when distinguishing between the pair of rotors 10, 20, the upper one will be referred to as the first rotor 10 and the lower one will be referred to as the second rotor 20. The first rotor 10 and the second rotor 20 are connected to each other to form a rotor assembly 2.

[0019] As shown in FIG. 1 , the first rotor 10 includes a first frame 16 , a first yoke portion 13 , a first magnet group 11 , and a first bearing 17 .

[0020] The first frame 16 has a bearing holder 16a, a disk portion 16b, and a cylindrical portion 16c. The bearing holder 16a holds the outer ring of the first bearing 17 from the radially outer side. The inner ring of the first bearing 17 holds the outer peripheral surface of a shaft 61 of a stator 60 (described later). This allows the first rotor 10 to be rotatably supported relative to the stator 60. The disk portion 16b extends radially outward from the bearing holder 16a. The cylindrical portion 16c has a cylindrical shape centered on the central axis J. The cylindrical portion 16c extends downward from the outer edge of the disk portion 16b. The cylindrical portion 16c surrounds the stator 60 from the radially outer side. The cylindrical portion 16c is provided with a plurality of ventilation holes 16w arranged along the circumferential direction.

[0021] The first yoke portion 13 has a plate shape extending along a plane perpendicular to the central axis J. The first yoke portion 13 is fixed to the lower surface of the disk portion 16b of the first frame 16. The first yoke portion 13 contacts the upper surface of the first magnet group 11.

[0022] As shown in FIG. 2 , the first magnet group 11 has an annular shape centered on the central axis J. The first magnet group 11 includes a plurality of main magnets 11a and a plurality of sub-magnets 11b. The first magnet group 11 has the same number of main magnets 11a and sub-magnets 11b. The main magnets 11a and sub-magnets 11b are permanent magnets. The main magnets 11a and sub-magnets 11b are arranged alternately in the circumferential direction. The main magnets 11a have a magnetization direction in the axial direction Z. On the other hand, the sub-magnets 11b have a magnetization direction in the circumferential direction. As a result, the first magnet group 11 forms a Halbach array.

[0023] As shown in FIG. 1 , the second rotor 20 includes a second frame 26 , a second yoke portion 23 , a second magnet group 21 , and a second bearing 27 .

[0024] The second frame 26 has a bearing holder 26a and a disk portion 26b. The bearing holder 26a holds the outer ring of the second bearing 27 from the radially outer side. The inner ring of the second bearing 27 holds the outer peripheral surface of a shaft 61 of a stator 60 (described later). This allows the second rotor 20 to be rotatably supported relative to the stator 60. The disk portion 26b extends radially outward from the bearing holder 26a. The lower end of the cylindrical portion 16c of the first rotor 10 is connected to the outer edge of the disk portion 26b. This allows the first rotor 10 and the second rotor 20 to be fixed to each other.

[0025] The second yoke portion 23 has a plate shape extending along a plane perpendicular to the central axis J. The second yoke portion 23 is fixed to the upper surface of the disk portion 26b of the second frame 26. The second yoke portion 23 contacts the lower surface of the second magnet group 21.

[0026] 2, the second magnet group 21 is annular and centered on the central axis J. The second magnet group 21 has a configuration substantially similar to that of the first magnet group 11. That is, the second magnet group 21 includes a plurality of main magnets 21a and a plurality of sub-magnets 21b arranged alternately in the circumferential direction. The second magnet group 21 forms a Halbach array.

[0027] The first magnet group 11 and the second magnet group 21 have opposite magnetic poles facing the stator 60. That is, the magnetic pole of the second rotor 20 arranged at a position overlapping the N pole of the first rotor 10 in the axial direction Z is an S pole. Similarly, the magnetic pole of the second rotor 20 arranged at a position overlapping the S pole of the first rotor 10 in the axial direction Z is an N pole.

[0028] <Stator> The stator 60 is located below the first rotor 10 and above the second rotor 20. When viewed from the axial direction Z, the stator 60 has an annular shape surrounding the central axis J.

[0029] As shown in FIG. 1 , the stator 60 includes a plurality of teeth 30 , a plurality of coils 63 , a first resin portion 40 , a second resin portion 50 , a plurality of bus bars 66 , 67 , 68 , 69 , and a shaft 61 .

[0030] FIG. 3 is a perspective view showing a plurality of teeth 30 of this embodiment.

[0031] The stator 60 of this embodiment is provided with twelve teeth 30. The teeth 30 of this embodiment are arranged at equal intervals in the circumferential direction.

[0032] 4 is a perspective view of the plurality of teeth 30 of this embodiment and the first resin portion 40 that holds the plurality of teeth 30. The first resin portion 40 is molded by insert molding, which embeds and holds the plurality of teeth 30. The plurality of teeth 30 are held in the first resin portion 40, thereby maintaining their relative positional relationship. The first resin portion 40 is made of an insulating resin material. In the following description, the plurality of teeth 30 and the first resin portion 40 in which the plurality of teeth 30 are insert-molded will be referred to as a molded part 40M.

[0033] FIG. 5 is a partially enlarged view of FIG. 4 . Each tooth 30 includes multiple steel sheet pieces 30p stacked along the stacking direction D1. The steel sheet pieces 30p are made of so-called electromagnetic steel sheets. In this embodiment, the stacking direction D1 is the radial direction. Each steel sheet piece 30p is rectangular. The axial dimensions of each steel sheet piece 30p are equal to each other. Furthermore, the circumferential width dimensions of each steel sheet piece 30p are different from each other. In each tooth 30, the center positions of the width dimensions of the multiple steel sheet pieces 30p are aligned with each other. Furthermore, in each tooth 30, the width dimensions of the multiple steel sheet pieces 30p gradually increase toward the radially outer side, which is one side of the stacking direction D1, and decrease toward the radially outer side only near the radially outer end. Therefore, each tooth 30 has a generally triangular shape whose circumferential dimension increases toward the radially outer side.

[0034] As shown in FIG. 4 , the first resin portion 40 has a plurality of insulator portions 42 , a bottom wall portion 41 , an outer wall portion 44 , and an inner wall portion 43 .

[0035] The insulator portions 42 are provided in the same number as the teeth 30. The insulator portions 42 cover at least a portion of the outer surface of the teeth 30. As shown in Fig. 2, the insulator portions 42 are located between the teeth 30 and the coils 63, and ensure insulation between the teeth 30 and the coils 63. The bottom wall portion 41 covers the multiple coils 63 from below (one side in the axial direction Z).

[0036] As shown in Fig. 4, the bottom wall portion 41 has a plate shape extending along a plane perpendicular to the central axis J. The bottom wall portion 41 has an annular shape centered on the central axis J. The bottom wall portion 41 is connected to the lower ends of the insulator portions 42. As a result, the bottom wall portion 41 connects the multiple insulator portions 42 together. The bottom wall portion 41 also connects the outer wall portion 44 and the inner wall portion 43.

[0037] The outer wall portion 44 has a cylindrical shape centered on the central axis J. The outer wall portion 44 extends upward from the outer edge of the bottom wall portion 41. The outer wall portion 44 surrounds the plurality of teeth 30 from the radially outer side.

[0038] The inner wall portion 43 has a cylindrical shape centered on the central axis J. The inner wall portion 43 extends upward from the inner edge of the bottom wall portion 41. The inner wall portion 43 is located radially inward of the plurality of teeth 30. The inner wall portion 43 has three anti-rotation portions 43a and three notches 43b. The anti-rotation portions 43a protrude radially inward from the inner circumferential surface of the inner wall portion 43. The anti-rotation portions 43a extend in a rib-like manner along the axial direction Z. The three anti-rotation portions 43a are arranged at equal intervals along the circumferential direction. The notches 43b extend downward from the upper end of the inner wall portion 43. The notches 43b penetrate the inner wall portion 43 in the radial direction. The three notches 43b are arranged at equal intervals along the circumferential direction. The notches 43b are located between two circumferentially adjacent anti-rotation portions 43a.

[0039] According to the present embodiment, the first resin portion 40 has a plurality of insulator portions 42 and an inner wall portion 43 connecting the plurality of insulator portions 42 to each other. Therefore, the first resin portion 40 of the present embodiment can hold the plurality of teeth 30 and fix the plurality of teeth 30 relative to each other. According to the present embodiment, the first resin portion 40, which functions as an insulator, also has the function of fixing the plurality of teeth 30 to each other. Therefore, compared to a case where separate components are prepared to perform these functions, the number of parts of the stator 60 can be reduced and the structure of the stator 60 can be simplified. Furthermore, compared to a case where teeth provided with insulators are separately connected to each other, the manufacturing process can be simplified and the stator 60 can be manufactured inexpensively.

[0040] 5 , the surfaces of the teeth 30 are provided with exposed portions 31 that are exposed from the insulator portions 42. That is, the insulator portions 42 do not cover the exposed portions 31 of the teeth 30. The exposed portions 31 have a pair of exposed end faces 32 and an exposed outer surface 33.

[0041] One of the pair of exposed end faces 32 is located on the upper surface 30a of the tooth 30, exposing the entire upper surface 30a from the insulator portion 42. The other of the pair of exposed end faces 32 is located on the lower surface 30b of the tooth 30, exposing the entire lower surface 30b from the insulator portion 42. That is, the pair of exposed end faces 32 are each located on an end surface of the tooth 30 facing the axial direction Z. As shown in FIG. 2 , the upper surface 30a of the tooth 30 faces the first rotor 10 in the axial direction Z and allows magnetic flux to flow toward the first rotor 10. The lower surface 30b of the tooth 30 faces the second rotor 20 in the axial direction Z and allows magnetic flux to flow toward the second rotor 20. According to this embodiment, the upper surface 30a and the lower surface 30b of the tooth 30 are exposed from the first resin portion 40, so that the first resin portion 40 does not enter the air gap between the stator 60 and the pair of rotors 10, 20. This makes it easier to reduce the air gap and improve torque.

[0042] 5 , the exposed outer surface 33 is continuous with one of the exposed end surfaces 32. The exposed outer surface 33 faces a direction perpendicular to the axial direction Z. The exposed outer surface 33 has a first exposed surface (exposed surface) 33 a at its radially outer end facing radially outward, a second exposed surface (exposed surface) 33 b at its radially inner end facing radially inward, and an upper end exposed portion 33 c located at the upper end of the tooth 30.

[0043] The first exposed surface 33a is provided on the radially outward facing surface of one of the steel plate pieces 30p located at the outermost radial position. The second exposed surface 33b is provided on the radially inward facing surface of one of the steel plate pieces 30p located at the innermost radial position. Therefore, the first exposed surface 33a and the second exposed surface face in opposite directions. The first exposed surface 33a has a first linear portion (linear portion) 33aa extending linearly along the axial direction Z. Similarly, the second exposed surface 33b has a second linear portion (linear portion) 33ba extending linearly along the axial direction Z. In this embodiment, the first linear portion 33aa and the second linear portion 33ba each have a uniform width extending from the upper end to the lower end of the steel plate piece 30p. Furthermore, in this embodiment, the width dimensions of the first linear portion 33aa and the second linear portion 33ba are equal to each other. However, the width dimension of the first linear portion 33aa and the width dimension of the second linear portion 33ba may be different from each other.

[0044] The upper end exposed portion 33c is a surface (side surface) of the outer peripheral surface of the tooth 30 that is perpendicular to the axial direction and is provided in a region that continues to the upward-facing exposed end surface 32. The upper end exposed portion 33c is configured such that a radial surface and a circumferential surface are connected in a stepped manner. The upper end exposed portion 33c connects the first exposed surface 33a and the second exposed surface 33b.

[0045] Fig. 6 is a schematic cross-sectional view taken along the radial direction of a mold 90 that molds the first resin portion 40 of this embodiment. Fig. 7 is a cross-sectional view taken along the radial direction along line VII-VII in Fig. 6. Figs. 6 and 7 show the teeth 30 embedded in the first resin portion 40. Note that Fig. 6 is a cross-section of a portion slightly shifted from the circumferential center of the teeth 30.

[0046] 6 , the mold 90 has a first die 91, a second die 92, and a pressing portion 93. The first die 91 and the second die 92 are disposed facing each other in the axial direction Z. A cavity C is provided between the first die 91 and the second die 92. The mold 90 can open the cavity C to the outside by moving the first die 91 and the second die 92 relatively along the axial direction Z.

[0047] The cavity C includes a plurality of first spaces C1 and one second space C2. The first spaces C1 are used to mold the insulator portions 42 (see FIG. 4 ). The teeth 30 are disposed in the first spaces C1. The molten resin material flows into the gap between the inner surfaces of the first spaces C1 and the outer surfaces of the teeth 30, hardens, and forms the insulator portions 42. The second spaces C2 are used to mold the bottom wall portions 41 (see FIG. 4 ). The second spaces C2 connect the plurality of first spaces C1 to each other. Although not shown, the cavity C has separate regions for molding the inner wall portions 43 and the outer wall portions 44 in addition to the first spaces C1 and the second spaces C2.

[0048] In this embodiment, the first die 91 has a first opposing surface 91g facing the second die 92 (i.e., upward). The first opposing surface 91g is a flat surface extending along a plane perpendicular to the axial direction Z. The second die 92 has a second opposing surface 92g facing the first die 91 (i.e., downward). The second space C2 is provided in the gap between the first opposing surface 91g and the second opposing surface 92g. The second opposing surface 92g is provided with a recess 92e recessed upward. The first space C1 is provided inside the recess 92e. Furthermore, an accommodating recess 92d recessed further upward is provided at the bottom of the recess 92e. That is, the accommodating recess 92d is provided on the inner surface of the mold 90. The upper end (end in the axial direction Z) of the tooth 30 is accommodated in the accommodating recess 92d. The accommodation recess 92d has a bottom surface 92b facing downward and a side surface 92c extending downward from the bottom surface 92b. The side surface 92c of the accommodation recess 92d has a stepped shape that follows the outline of the side surface of the tooth 30 when viewed from the axial direction Z.

[0049] In this embodiment, within the cavity C, the lower surfaces 30b of the teeth 30 contact the first opposing surface 91g, and the upper surfaces 30a of the teeth 30 contact the bottom surfaces 92b of the accommodating recesses 92d. That is, the teeth 30 within the cavity C are sandwiched between the first opposing surface 91g and the bottom surface 92b from the top-bottom direction. This positions the teeth 30 in the axial direction Z within the cavity C. Furthermore, the upper surfaces 30a and lower surfaces 30b of the teeth 30 contact the inner surfaces of the mold 90, and therefore do not come into contact with the molten resin material within the cavity C. Therefore, these portions are exposed from the first resin portion 40 as exposed end surfaces 32 after the first resin portion 40 is molded.

[0050] In this embodiment, the upper ends of the teeth 30 are accommodated in the accommodation recesses 92d. Furthermore, the upper ends of the side surfaces of the teeth 30 contact the side surfaces 92c of the accommodation recesses 92d. This allows the multiple steel plate pieces 30p constituting the teeth 30 to be aligned in the stacking direction D1 with the centers of their widths aligned with one another. This positions the multiple steel plate pieces 30p in the cavity C in a direction perpendicular to the axial direction Z. Furthermore, the upper ends of the side surfaces of the teeth 30 contact the inner surface of the mold 90 (more specifically, the side surfaces 92c of the accommodation recesses 92d), and therefore do not come into contact with the molten resin material in the cavity C. Therefore, after the first resin portion 40 is molded, these portions are exposed from the first resin portion 40 as exposed upper end portions 33c (see FIG. 5 ).

[0051] The manufacturing method for manufacturing the stator 60 of this embodiment includes an arrangement process of arranging the multiple teeth 30 in the cavity C of the mold 90, and a molding process of molding the first resin portion 40. In the molding process, molten resin material is injected into the cavity C. The injected resin material hardens to form the first resin portion 40. In other words, the molding process is a process of filling the cavity C with resin and molding the first resin portion 40. In addition, the molding process is a process of forming insulator portions 42 on the surfaces of the teeth 30 and holding the multiple teeth 30 with the first resin portion 40.

[0052] According to the manufacturing method of this embodiment, in the molding process, the plurality of insulator portions 42 are molded, and the bottom wall portion 41 connecting the plurality of insulator portions 42 is also molded. Therefore, in the molding process, the insulator portions 42 are molded, and the plurality of teeth 30 can be fixed relative to each other.

[0053] Furthermore, according to this embodiment, since the insulator portions 42 are formed by insert molding, it is easier to form the insulator portions 42 thinner than when pre-formed insulators are attached to the teeth. Therefore, according to this embodiment, as shown in Fig. 2, the space factor of the coils attached to the teeth 30 via the insulator portions 42 can be increased, and the magnetic characteristics of the stator 60 can be improved.

[0054] 4 , the teeth 30 of the stator 60 manufactured by the manufacturing method of this embodiment are provided with exposed portions 31 having a pair of exposed end faces 32 and an exposed outer surface 33. According to the stator 60 of this embodiment, by providing the pair of exposed end faces 32 and the exposed outer surface 33 on the surfaces of the teeth 30, the teeth 30 can be brought into contact with the mold 90 at the pair of exposed end faces 32 and the exposed outer surface 33 when molding the first resin portion 40. This improves the positioning accuracy of the teeth 30 relative to the mold 90, and stabilizes the performance of the stator 60.

[0055] 6, in the arrangement step and molding step of this embodiment, the inner surface of the accommodation recess 92d of the mold 90 contacts the end faces of the teeth 30 facing the axial direction Z (i.e., the pair of exposed end faces 32) and the outer surface (i.e., the exposed outer surface 33) that is connected to the end faces and faces perpendicular to the axial direction. According to this embodiment, the teeth 30 can be held on the inner surface of the accommodation recess 92d in the arrangement step and molding step, allowing the multiple teeth 30 to be positioned when insert molding is performed. The manufacturing method of this embodiment makes it possible to form a stator 60 with excellent relative geometric tolerances between the multiple teeth 30.

[0056] As shown in FIG. 7, the second die 92 has a protrusion 92a provided on the inner surface of the first space C1 of the cavity C, and a slide accommodating portion 92h.

[0057] The protrusion 92a protrudes radially outward from the radially inner end of the inner surface of the first space C1. The protrusion 92a may be located at the end of the steel plate pieces 30p in the stacking direction D1 on the inner surface of the first space C1. In this embodiment, the protrusion 92a extends in the axial direction Z with a uniform width. The tip surface of the protrusion 92a is a flat surface perpendicular to the stacking direction D1. In the following description, the tip surface of the protrusion 92a will be referred to as the first pressing surface 92f. The first pressing surface 92f contacts the radially inward surface of one of the multiple steel plate pieces 30p that constitute the teeth 30 arranged in the cavity C, which is located most radially inner.

[0058] The slide accommodating portion 92h is recessed radially outward from the radially outer end of the inner surface of the first space C1. The slide accommodating portion 92h may be located at the end of the inner surface of the first space C1 opposite the protruding portion 92a in the stacking direction D1. The slide accommodating portion 92h in this embodiment has a uniform width and extends in the axial direction Z like a groove.

[0059] The pressing portion 93 is a square prism-shaped block extending along the axial direction Z. The pressing portion 93 is accommodated in the slide accommodating portion 92h. The tip of the pressing portion 93 protrudes radially inward from the slide accommodating portion 92h. The tip surface of the pressing portion 93 is a flat surface perpendicular to the stacking direction D1. In the following description, the tip surface of the pressing portion 93 is referred to as the second pressing surface 93f. The second pressing surface 93f contacts the radially outward facing surface of one of the multiple steel plate pieces 30p that constitute the tooth 30 arranged in the cavity C, which is located at the outermost radial position.

[0060] The pressing portion 93 is movable in the radial direction (i.e., the stacking direction D1) while contacting the inner surface of the slide accommodating portion 92h. A pressing mechanism 99 is provided inside the slide accommodating portion 92h to apply stress to the radially outer end surface of the pressing portion 93. The pressing mechanism 99 may be, for example, a hydraulic mechanism or a spring. The pressing portion 93 presses the second pressing surface 93f against the radially outer side of the tooth 30 by the action of the pressing mechanism 99.

[0061] The inner surface of the mold 90 of this embodiment is provided with a pair of pressing surfaces 92f, 93f that come into contact with end faces on one side and the other side in the stacking direction D1 of the teeth 30. According to the molding process of this embodiment, the first resin portion 40 is insert-molded while the end faces on one side and the other side in the stacking direction D1 of the teeth 30 are supported by the pair of pressing surfaces 92f, 93f. According to this embodiment, it is possible to prevent gaps from being formed among the stacked steel plate pieces 30p in the cavity C, and to prevent molten resin material from entering between the stacked steel plate pieces 30p.

[0062] The die 90 of this embodiment can hold multiple steel plate pieces 30p together within the cavity C using a pair of pressing surfaces 92f, 93f. Generally, in conventional manufacturing methods, teeth are placed in the cavity after a preliminary process of fixing multiple steel plate pieces to each other by crimping, welding, or the like. In contrast, according to this embodiment, the die 90 holds the multiple steel plate pieces 30p without gaps, so the preliminary process can be omitted. That is, according to this embodiment, the multiple steel plate pieces 30p can be fixed to each other using only the first resin portion 40, thereby simplifying the manufacturing process of the stator 60. According to this embodiment, there is no need to crimp or weld the steel plate pieces 30p, so deterioration of the magnetic properties of the steel plate pieces 30p due to crimping or welding can be suppressed.

[0063] As shown in FIG. 5 , the teeth 30 of the stator 60 manufactured by the manufacturing method of this embodiment have a pair of exposed surfaces (first exposed surface 33 a, second exposed surface 33 b) on one end surface and the other end surface in the stacking direction D1 as traces of the pair of pressing surfaces 92 f, 93 f. According to the stator 60 of this embodiment, by providing the first exposed surface 33 a and the second exposed surface 33 b on the surface of the teeth 30, the teeth 30 can be brought into contact with the mold 90 at both end surfaces in the stacking direction D1 of the plurality of steel plate pieces 30 p during molding of the first resin portion 40. This prevents gaps from forming between the plurality of steel plate pieces 30 p. Furthermore, the stator 60 can be configured to fix the steel plate pieces 30 p together without crimping, thereby improving the magnetic performance of the stator 60.

[0064] As shown in FIG. 7 , the mold 90 of this embodiment has a pressing portion 93 movable in the stacking direction D1. The pressing portion 93 is disposed on the inner surface of the mold 90 that surrounds the cavity C and faces the stacking direction D1. The pressing portion 93 has a first pressing surface 93f, which is one pressing surface, and presses the teeth 30 against a second pressing surface 92f, which is the other pressing surface. According to this embodiment, when the steel plate pieces 30p are not fixed to each other by caulking or the like, insert molding while applying appropriate pressure using the movable pressing portion can further prevent resin from seeping between the steel plate pieces 30p. Furthermore, according to this embodiment, compared to a case where only a non-movable pressing portion is provided, since the steel plate pieces 30p are more easily fixed to the mold 90, the intrusion of resin material between the steel plate pieces 30p can be prevented even when the dimensional accuracy of the mold 90 is low. This allows the mold 90 to be manufactured inexpensively, thereby reducing the manufacturing cost of the stator 60.

[0065] 5 , the stator 60 manufactured by the manufacturing method of this embodiment has a first linear portion 33aa on the first exposed surface 33a and a second linear portion 33ba on the second exposed surface 33b. The first linear portion 33aa is a trace of contact with the second pressing surface 93f during molding of the first resin portion 40. Similarly, the second linear portion 33ba is a trace of contact with the first pressing surface 92f during molding of the first resin portion 40. According to the stator 60 of this embodiment, by providing the first linear portion 33aa and the second linear portion 33ba extending along the axial direction Z on the end surfaces of the teeth 30 in the stacking direction D1, it is possible to bring the pressing surfaces 92f, 93f extending along the axial direction Z into contact with both end surfaces of the plurality of steel plate pieces 30p in the stacking direction D1 during molding of the first resin portion 40. This allows the entire area of ​​the steel plate pieces 30p in the axial direction Z to be pressed against the inner surface of the mold 90 in the stacking direction D1, more reliably preventing gaps from being formed between the steel plate pieces 30p.

[0066] The shapes of the first linear portion 33aa and the second linear portion 33ba are formed by transferring the shapes of the first pressing surface 92f and the second pressing surface 93f, respectively. Therefore, the shapes of the first linear portion 33aa and the second linear portion 33ba can be freely changed by changing the shapes of the first pressing surface 92f and the second pressing surface 93f. The shapes of the first linear portion 33aa and the second linear portion 33ba may be changed within a range that can sufficiently hold the multiple steel plate pieces 30p in the stacking direction D1, suppress contact between the teeth 30 and the coils 63 as the insulator portion 42, and ensure releasability from the mold 90. The shapes of the first linear portion 33aa and the second linear portion 33ba do not have to be linear. They may also be trapezoidal, with widths increasing upward or downward, or may be discontinued in the axial direction Z without reaching the upper end.

[0067] 5 , in this embodiment, the width of the first straight portion 33aa is preferably smaller than the width of one of the steel plate pieces 30p located at the radially outer end of the plurality of steel plate pieces 30p constituting the tooth 30. Similarly, the width of the second straight portion 33ba is preferably smaller than the width of one of the steel plate pieces 30p located at the radially inner end of the plurality of steel plate pieces 30p constituting the tooth 30. This allows the circumferential end of the surface of the steel plate piece 30p located at the radial end, facing the stacking direction, to be covered by the first resin portion 40, thereby preventing the steel plate piece 30p from detaching from the tooth 30. Furthermore, by covering the circumferential end of the end steel plate piece 30p with the first resin portion 40, the first resin portion 40 can easily prevent direct contact between the end steel plate piece 30p and the coil 63. Additionally, according to this embodiment, by covering the circumferential ends of the end steel plate pieces 30p with the first resin portion 40, the resin material molten in the cavity C can easily flow around the side surfaces of the teeth 30 along the outer periphery of the teeth 30. This makes it possible to stably mold insulator portions 42 with a uniform thickness. This effect becomes more pronounced when protrusions 130g are provided on the outer periphery of the teeth 30 (see FIG. 15, which will be described later as a modified example).

[0068] 8 to 10 are perspective views showing the process of assembling each component to molded component 40M. Fig. 8 shows the state where multiple coils 63 and multiple bus bars 66, 67, 68, and 69 are attached to molded component 40M, Fig. 9 shows the state where shaft 61 is further attached, and Fig. 10 shows the state where second resin portion 50 is further molded.

[0069] 8 , the coils 63 are attached to the teeth 30, respectively. The coils 63 in this embodiment are made of, for example, a strip-shaped coil wire whose thickness direction is the axial direction Z. The strip-shaped coil wire extends in a spiral shape along the outer periphery of the teeth 30.

[0070] The stator 60 of this embodiment is provided with twelve coils 63. The twelve coils 63 are classified into four U-phase coils 63U, four V-phase coils 63V, and four W-phase coils 63W. That is, the multiple coils 63 are classified into multiple phase coils 63. AC currents of the same phase flow through the multiple coils 63 of the same phase. Furthermore, AC currents flowing through the coils 63 of different phases are out of phase with each other. In this embodiment, AC currents with phases shifted by 120° flow through the U-phase coils 63U, V-phase coils 63V, and W-phase coils 63W, respectively. Note that the number of coils 63 for each phase is not limited to that of this embodiment.

[0071] The multiple bus bars 66, 67, 68, 69 are plate-shaped with their thickness direction aligned with the axial direction Z. The multiple bus bars 66, 67, 68, 69 are strip-shaped with their width direction aligned with the radial direction and extend in an arc shape along the circumferential direction. In this embodiment, the three connection bus bars 66, 67, 68 have the same shape. Furthermore, the neutral point bus bar 69 has a larger circumferential length than the connection bus bars 66, 67, 68.

[0072] The multiple bus bars 66, 67, 68, and 69 connect the coils 63 to one another. In this embodiment, the multiple bus bars 66, 67, 68, and 69 include three connecting bus bars 66, 67, and 68 that connect the coils 63 of the same phase and one neutral bus bar 69 that connects the three-phase coils 63. The three connecting bus bars 66, 67, and 68 include a U-phase connecting bus bar 66, a V-phase connecting bus bar 67, and a W-phase connecting bus bar 68. In this embodiment, the multiple bus bars 66, 67, 68, and 69 connect the multiple coils 63 to form a Y-connection. As shown in FIG. 2 , power supply lines 62 that pass AC current through the coils 63 of each phase are connected to the U-phase coil 63U, the V-phase coil 63V, and the W-phase coil 63W, respectively. That is, the stator 60 has three power supply lines 62. Each power supply line 62 is connected to an external power supply.

[0073] The multiple bus bars 66, 67, 68, and 69 are arranged side by side at intervals along the axial direction Z. According to this embodiment, the multiple bus bars 66, 67, 68, and 69 overlap one another as viewed in the axial direction Z. According to this embodiment, the multiple bus bars 66, 67, 68, and 69 can be arranged in a concentrated manner as viewed in the axial direction Z, thereby reducing the radial dimension of the stator 60. Furthermore, since each of the bus bars 66, 67, 68, and 69 in this embodiment has a plate shape with the axial direction Z as its thickness direction, even when the bus bars are arranged overlapping one another in the axial direction Z, an increase in the size of the stator 60 in the axial direction Z can be suppressed.

[0074] FIG. 11 is a perspective view showing multiple teeth 30, a U-phase connecting bus bar 66, and multiple U-phase coils 63U of this embodiment. FIG. 12 is a perspective view showing multiple teeth 30, a V-phase connecting bus bar 67, and multiple V-phase coils 63V of this embodiment. FIG. 13 is a perspective view showing multiple teeth 30, a W-phase connecting bus bar 68, and multiple W-phase coils 63W of this embodiment. FIGS. 11 to 13 illustrate the circumferential direction θ around the central axis J. In the following description, the direction in which the arrow indicating the circumferential direction θ in the figures points is referred to as one circumferential side (+θ), and the opposite side is referred to as the other circumferential side (−θ).

[0075] As shown in FIG. 11 , the four U-phase coils 63U in this embodiment are divided into two sets (a first set 1U and a second set 2U) each including two U-phase coils 63U. The U-phase coils 63U of the same set are attached to circumferentially adjacent teeth 30. Four teeth 30 for attaching coils 63 of other phases are arranged between the U-phase coils 63U of different sets in the circumferential direction. The circumferentially adjacent U-phase coils 63U of the same set are connected to each other at bridge portions (not shown). The U-phase coils 63U of different sets are connected to each other by U-phase connecting bus bars 66.

[0076] The U-phase coil 63U located on one circumferential side (+θ) of the U-phase coils 63U of the first set 1U and the U-phase coil 63U located on the other circumferential side (−θ) of the U-phase coils 63U of the second set 2U each have a first connection portion 63Ua. The first connection portion 63Ua extends radially inward from the U-phase coil 63U. A U-phase connecting bus bar 66 is connected to the upper surface of the tip end of the first connection portion 63Ua. This connects the two sets of U-phase coils 63U to each other. The first connection portion 63Ua and the U-phase connecting bus bar 66 are electrically connected by means such as resistance welding.

[0077] Of the U-phase coils 63U of the first set 1U, the U-phase coil 63U located on the other circumferential side (-θ) has a second connection portion 63Ub. The second connection portion 63Ub extends radially inward from the U-phase coil 63U. The top surface of the tip of the second connection portion 63Ub is connected to a power supply line 62 that is connected to an external power supply. The second connection portion 63Ub and the power supply line 62 are electrically connected by means of, for example, soldering.

[0078] Of the U-phase coils 63U of the second set 2U, the U-phase coil 63U located on one circumferential side (+θ) has a third connection portion 63Un. The third connection portion 63Un extends radially inward from the U-phase coil 63U. A neutral point bus bar 69 is connected to the upper surface of the tip end of the third connection portion 63Un. This connects the third connection portion 63Un of the U-phase coil 63U to the third connection portion of the other phase. The third connection portion 63Un and the neutral point bus bar 69 are electrically connected by means such as resistance welding.

[0079] As shown in FIG. 12 , the four V-phase coils 63V in this embodiment are divided into two sets (a third set 3V and a fourth set 4V) each including two V-phase coils 63V. The V-phase coils 63V of the same set are attached to circumferentially adjacent teeth 30. Furthermore, four teeth 30 for attaching coils 63 of other phases are arranged between the V-phase coils 63V of different sets in the circumferential direction. The circumferentially adjacent V-phase coils 63V of the same set are connected to each other at crossover portions (not shown). The V-phase coils 63V of different sets are connected to each other by a V-phase connecting bus bar 67.

[0080] The V-phase coil 63V located on one circumferential side (+θ) of the V-phase coils 63V of the third set 3V and the V-phase coil 63V located on the other circumferential side (−θ) of the V-phase coils 63V of the fourth set 4V each have a first connection portion 63Va. The first connection portion 63Va extends radially inward from the V-phase coil 63V. A V-phase connecting bus bar 67 is connected to the upper surface of the tip end of the first connection portion 63Va. This connects the two sets of V-phase coils 63V to each other. The first connection portion 63Va and the V-phase connecting bus bar 67 are electrically connected by means such as resistance welding.

[0081] Of the V-phase coils 63V of the third set 3V, the V-phase coil 63V located on the other circumferential side (-θ) has a second connection portion 63Vb. Second connection portion 63Vb extends radially inward from V-phase coil 63V. The top surface of the tip of second connection portion 63Vb is connected to a power supply line 62 that is connected to an external power supply. Second connection portion 63Vb and power supply line 62 are electrically connected by means of, for example, soldering.

[0082] Of the V-phase coils 63V of the fourth set 4V, the V-phase coil 63V located on one circumferential side (+θ) has a third connection portion 63Vn. The third connection portion 63Vn extends radially inward from the V-phase coil 63V. A neutral point bus bar 69 is connected to the upper surface of the tip end of the third connection portion 63Vn. This connects the third connection portion 63Vn of the V-phase coil 63V to the third connection portion of the other phase. The third connection portion 63Vn and the neutral point bus bar 69 are electrically connected by means such as resistance welding.

[0083] As shown in FIG. 13 , the four W-phase coils 63W in this embodiment are divided into two sets (a fifth set 5W and a sixth set 6W) each including two W-phase coils 63W. The W-phase coils 63W in the same set are attached to circumferentially adjacent teeth 30. Four teeth 30 for attaching coils 63 of other phases are arranged between the W-phase coils 63W in different sets in the circumferential direction. The circumferentially adjacent W-phase coils 63W in the same set are connected to each other at crossover portions (not shown). The W-phase coils 63W in different sets are connected to each other by W-phase connecting bus bars 68.

[0084] The W-phase coil 63W located on one circumferential side (+θ) of the W-phase coils 63W of the fifth set 5W and the W-phase coil 63W located on the other circumferential side (−θ) of the W-phase coils 63W of the sixth set 6W each have a first connection portion 63Wa. The first connection portion 63Wa extends radially inward from the W-phase coil 63W. A W-phase connecting bus bar 68 is connected to the upper surface of the tip end of the first connection portion 63Wa. This connects the two sets of W-phase coils 63W to each other. The first connection portion 63Wa and the W-phase connecting bus bar 68 are electrically connected by means such as resistance welding.

[0085] Of the W-phase coils 63W of the fifth set 5W, the W-phase coil 63W located on the other circumferential side (-θ) has a second connection portion 63Wc. Second connection portion 63Wc extends radially inward from W-phase coil 63W. An upper surface of a tip end of second connection portion 63Wc is connected to power supply line 62 that is connected to an external power supply. Second connection portion 63Wc and power supply line 62 are electrically connected by means of, for example, soldering.

[0086] Of the W-phase coils 63W of the sixth set 6W, the W-phase coil 63W located on one circumferential side (+θ) has a third connection portion 63Wn. The third connection portion 63Wn extends radially inward from the W-phase coil 63W. A neutral point bus bar 69 is connected to the upper surface of the tip end of the third connection portion 63Wn. This connects the third connection portion 63Wn of the W-phase coil 63W to the third connection portion of the other phase. The third connection portion 63Wn and the neutral point bus bar 69 are electrically connected by means such as resistance welding.

[0087] As described above, in this embodiment, some (six in this embodiment) of the multiple coils 63 have first connection portions 63Ua, 63Va, 63Wa connected to the connection bus bars 66, 67, 68. Some (three in this embodiment) of the multiple coils 63 have second connection portions 63Ub, 63Vb, 63Wc connected to the power supply line 62. Furthermore, some (three in this embodiment) of the multiple coils 63 have third connection portions 63Un, 63Vn, 63Wn connected to the neutral point bus bar 69.

[0088] As shown in FIG. 11 , two first connection portions 63Ua connected by a U-phase connecting bus bar 66 are positioned at the same height. As shown in FIG. 12 , two first connection portions 63Va connected by a V-phase connecting bus bar 67 are positioned at the same height. As shown in FIG. 13 , two first connection portions 63Wa connected by a W-phase connecting bus bar 68 are positioned at the same height. That is, the axial positions of the first connection portions 63Ua, 63Va, and 63Wa of the same phase connected by any one of the connecting bus bars 66, 67, and 68 are aligned. According to this embodiment, the connecting bus bars 66, 67, and 68 can be positioned along a plane perpendicular to the central axis J over their entire lengths. That is, there is no need to provide the connecting bus bars 66, 67, and 68 with portions that bend in the axial direction Z, simplifying the structure of the connecting bus bars 66, 67, and 68. Furthermore, according to this embodiment, the connection bus bars 66, 67, 68 are supported at both ends by the first connection portions 63Ua, 63Va, 63Wa, which are at the same height, so there is no need to provide a separate structure to support the connection bus bars 66, 67, 68. This allows the structure around the connection bus bars 66, 67, 68 in the stator 60 to be simplified.

[0089] As shown in FIG. 11 , the two U-phase first connection portions 63Ua of this embodiment extend linearly from the lower end of the coil 63. That is, the U-phase first connection portion 63Ua does not have a bent portion bending in the axial direction Z, thereby reducing the processing costs of the connection portions. On the other hand, as shown in FIGS. 12 and 13 , the V-phase and W-phase first connection portions 63Va, 63Wa of this embodiment have bent portions bending in the axial direction Z. The circumferential positions θ of the V-phase and W-phase first connection portions 63Va, 63Wa overlap with the region in which the U-phase connecting bus bar 66 extends in the circumferential direction θ. Furthermore, since the U-phase connecting bus bar 66 is connected to the U-phase first connection portion 63Ua extending from the lower end of the coil 63, it is positioned in the axial direction Z near the axial position of the lower end of the coil 63. By providing the bent portion 6, the first connection portions 63Va, 63Wa of the V phase and the W phase are disposed at their radially inner ends above the U-phase connecting bus bar 66. In this embodiment, the first connection portions 63Va, 63Wa of the V phase and the W phase each have the bent portion 6, thereby suppressing interference with the U-phase connecting bus bar 66.

[0090] As shown in FIGS. 11 and 13 , the U-phase second connection portion 63Ub and the W-phase second connection portion 63Wc of this embodiment extend linearly from the lower end of the coil 63. That is, the U-phase and V-phase second connection portions 63Ub, 63Wc do not have bent portions in the axial direction Z, thereby reducing the processing costs of the connection portions. The U-phase and W-phase second connection portions 63Ub, 63Wc are positioned at positions offset in the circumferential direction θ with respect to the region in which the U-phase connecting bus bar 66 extends in the circumferential direction θ. Therefore, even though the U-phase and V-phase second connection portions 63Ub, 63Wc do not have bent portions, there is no concern about interference with the U-phase connecting bus bar 66. On the other hand, as shown in FIG. 12 , the V-phase second connection portion 63Vb of this embodiment has a bent portion 6 bent in the axial direction Z. The position of the V-phase second connection portion 63Vb in the circumferential direction θ overlaps with the region of the U-phase connecting bus bar 66 extending in the circumferential direction θ. The V-phase second connection portion 63Vb is disposed above the U-phase connecting bus bar 66 at its radially inner end. In this embodiment, the V-phase second connection portion 63Vb has the bent portion 6, which reduces interference with the U-phase connecting bus bar 66.

[0091] As described above, according to the stator 60 of this embodiment, the axial direction Z position of at least one first connection portion (in this embodiment, the first connection portion 63Ua of the U-phase) among the plurality of first connection portions 63Ua, 63Va, 63Wa and at least one second connection portion (in this embodiment, the second connection portions 63Ub, 63Wc of the U-phase and W-phase) among the plurality of second connection portions 63Ub, 63Vb, 63Wc coincides with the axial direction Z position of the lower end portion of the coil 63. According to this embodiment, there is no need to provide bent portions in the first connection portion 63Ua and the second connection portions 63Ub, 63Wc, and therefore it is possible to reduce the processing costs of the connection portions.

[0092] 9 , the shaft 61 is a hollow shaft that extends in the axial direction Z around a central axis J. The shaft 61 is located radially inward of the plurality of teeth 30 and the plurality of bus bars 66, 67, 68, and 69. The shaft 61 in this embodiment is made of metal. Examples of the metal material that constitutes the shaft 61 include steel such as stainless steel, and aluminum alloy.

[0093] The shaft 61 of this embodiment has a hollow portion 61h and a plurality of holes 61g. The hollow portion 61h extends in the axial direction Z around the central axis J and opens at the upper and lower ends of the shaft 61. The holes 61g extend radially outward from the hollow portion 61h and open at the outer peripheral surface of the shaft 61. In the shaft 61 of this embodiment, three holes 61g are arranged at equal intervals along the circumferential direction.

[0094] As shown in FIG. 2 , the outer circumferential surface of the shaft 61 is provided with a large diameter portion 61d and two small diameter portions 61e. The two small diameter portions 61e are located above and below the large diameter portion 61d. The diameters of the two small diameter portions 61e on the outer circumferential surface of the shaft 61 are smaller than that of the large diameter portion 61d. The inner rings of the bearings 17 and 27 are fitted into the two small diameter portions 61e, respectively. The inner wall portion 43 of the first resin portion 40 is fitted into the large diameter portion 61d. The large diameter portion 61d and the inner wall portion 43 are fixed to each other by a fixing means such as an adhesive.

[0095] The holes 61g open radially outward in the large diameter portion 61d of the shaft 61. Power supply wires 62 are passed through the holes 61g. The stator 60 of this embodiment is provided with three power supply wires 62 for U-phase, V-phase, and W-phase. One power supply wire 62 for each phase is passed through each of the three holes 61g.

[0096] In the present embodiment, the multiple holes 61g are arranged to overlap a range R in the axial direction Z in which the multiple bus bars 66, 67, 68, and 69 are arranged. This allows the power supply line 62 to be connected to the second connection portions 63Ub, 63Vb, and 63Wc of the coil 63 in the range R in the axial direction Z in which the multiple bus bars 66, 67, 68, and 69 are arranged, and the stator 60 can be made smaller in the axial direction Z than when a separate area is provided for passing the power supply line 62 through.

[0097] As shown in FIG. 9 , the hole 61g overlaps the notch 43b of the inner wall portion 43 when viewed in the radial direction. This prevents the opening of the hole 61g from being blocked by the inner wall portion 43. Furthermore, the large diameter portion 61d is provided with a groove 61k extending along the axial direction Z. In this embodiment, three grooves 61k are provided on the outer circumferential surface of the shaft 61. The three grooves 61k are arranged at equal intervals in the circumferential direction. The anti-rotation portion 43a of the inner wall portion 43 shown in FIG. 8 is inserted into the groove 61k. A portion of the outer surface of the anti-rotation portion 43a and a portion of the inner circumferential surface of the groove 61k face each other in the circumferential direction. This prevents the shaft 61 from rotating relative to the first resin portion 40.

[0098] As shown in FIG. 10 , the second resin portion 50 covers at least a portion of the multiple coils 63. Also, as shown in FIG. 2 , the second resin portion 50 covers at least a portion of the bus bars 66, 67, 68, and 69. In this embodiment, the second resin portion 50 is an insulating potting material. The second resin portion 50 may be an adhesive. The uncured second resin portion 50 is filled into the region surrounded by the outer wall portion 44, the inner wall portion 43, and the bottom wall portion 41 of the first resin portion 40 and then cured. When the potting process is performed, the hole 61g of the shaft 61 is blocked in advance.

[0099] In this embodiment, the thermal conductivity of the material making up the second resin part 50 is preferably higher than the thermal conductivity of the material making up the first resin part 40. By using a material with high thermal conductivity for making up the second resin part 50, the second resin part 50 absorbs heat from the coil 63 and bus bars 66, 67, 68, and 69 embedded therein and dissipates the heat to the atmosphere or other components. This allows the second resin part 50 to cool the coil 63 and bus bars 66, 67, 68, and 69.

[0100] In the first resin part 40 of this embodiment, the upper end of the inner wall part 43 is located lower than the upper end of the outer wall part 44. The shaft 61 is inserted into the inner circumferential surface of the inner wall part 43. The second resin part 50 is filled up to the upper end of the outer wall part 44. Therefore, the second resin part 50 of this embodiment comes into contact with the outer circumferential surface of the metal shaft 61. The second resin part 50 can transfer heat from the coil 63 and the bus bars 66, 67, 68, and 69 to the shaft 61, which has a large heat capacity, and dissipate the heat from the shaft 61 to the outside air. This allows the second resin part 50 to efficiently cool the coil 63 and the bus bars 66, 67, 68, and 69.

[0101] It is preferable to use an appropriate resin material taking into consideration the high thermal conductivity, viscosity, etc. as the material for the second resin portion 50. The material for the second resin portion 50 may also contain a filler to increase the thermal conductivity.

[0102] <Method of Manufacturing Stator> Next, a method of manufacturing the stator 60 of this embodiment will be described.

[0103] The manufacturing method of the stator 60 includes a steel plate cutting process, an arrangement process, a forming process, an attachment process, and a filling process. In the manufacturing method of the stator 60 of this embodiment, the steel plate cutting process, the arrangement process, the forming process, the attachment process, and the filling process are performed in this order.

[0104] The steel plate cutting process is a process for manufacturing a plurality of steel plate pieces 30p as shown in FIG. 5 . The plurality of steel plate pieces 30p used for one tooth 30 are each rectangular plate-shaped. The plurality of steel plate pieces 30p have the same plate thickness and dimension in the axial direction Z. On the other hand, the plurality of steel plate pieces 30p have different width dimensions along the circumferential direction. In the steel plate cutting process of this embodiment, a strip-shaped steel plate is cut to form a plurality of steel plate pieces 30p. In the steel plate cutting process of this embodiment, the steel plate pieces 30p are formed by repeatedly cutting the strip-shaped steel plate along linear cutting lines in the length direction of the steel plate.

[0105] According to the steel plate cutting process of this embodiment, by changing the spacing between the cutting lines, it is possible to easily manufacture multiple types of steel plate pieces 30p used for one tooth 30. That is, according to the steel plate cutting process of this embodiment, it is possible to easily manufacture multiple rectangular steel plate pieces 30p having different width dimensions. Furthermore, according to the steel plate cutting process of this embodiment, no steel plate scraps are produced during manufacturing, compared to when steel plates are press-formed and laminated, and it is possible to increase the yield of steel plates.

[0106] The steel plate cutting step will be described in more detail later with reference to FIG. 14 showing a modified example of the steel plate cutting step.

[0107] 6, the arrangement process is a process of arranging the plurality of teeth 30 in the first space C1 of the cavity C. As described above, in this embodiment, the plurality of steel plate pieces 30p are not fixed in advance by caulking, welding, or the like. Therefore, in the arrangement process, the plurality of steel plate pieces 30p are stacked in the stacking direction D1, arranged in the cavity C, and supported by the mold 90. Furthermore, in this embodiment, the plurality of steel plate pieces 30p are held by a pair of pressing surfaces 92f, 93f.

[0108] The molding process is a process of manufacturing a molded part 40M (see FIG. 4) by filling a cavity C with resin. In the cavity C shown in FIG. 6, first spaces C1 for forming the insulator portions 42 are connected to each other via second spaces C2 for molding the bottom wall portions 41. Therefore, the multiple insulator portions 42 formed through the molding process are connected to each other by the bottom wall portions 41. Furthermore, each insulator portion 42 holds a tooth 30. Therefore, the multiple teeth 30 are fixed to each other through the molding process.

[0109] The mounting process is a process of mounting the coil 63, bus bars 66, 67, 68, and 69, and shaft 61 to the molded part 40M. As shown in FIG. 8 , in the mounting process, the coil 63 is mounted to the teeth 30 via the insulator portion 42. In this embodiment, the coil 63 is pre-formed into a spiral shape and then inserted into the teeth 30. In the mounting process, the bus bars 66, 67, 68, and 69 are joined to the coil using a joining method such as welding. As shown in FIG. 9 , in the mounting process, the shaft 61 is fixed to the first resin portion 40. Note that the shaft 61 may be embedded in the first resin portion 40 together with the plurality of teeth 30 by insert molding.

[0110] The filling step is a step of filling an uncured potting material into the area surrounded by the outer wall portion 44, the inner wall portion 43, and the bottom wall portion 41 of the first resin portion 40 and curing the potting material to form the second resin portion 50. If the second resin portion 50 is an ultraviolet-curable resin, the filled second resin portion 50 is irradiated with ultraviolet light.

[0111] The stator 60 of this embodiment is manufactured through the above steps.

[0112] <Modification> A modified steel plate cutting process that can be employed in the first embodiment and a modified tooth 130 manufactured through the steel plate cutting process will be described.

[0113] FIG. 14 is a schematic diagram showing the steel plate cutting process of this modified example.

[0114] As in the above-described embodiment, the steel plate cutting process is performed before the arranging process, and is a process for manufacturing a plurality of steel plate pieces 130p. As in the above-described embodiment, the steel plate cutting process is a process for cutting the strip-shaped steel plate 130A along cutting lines 139 extending along the width direction to form a plurality of steel plate pieces 130p. According to such a steel plate cutting process, a plurality of rectangular steel plate pieces 130p can be easily manufactured, and the yield of the steel plate can be increased.

[0115] In the steel plate cutting process, cutting blades having the same shape as the cutting lines 139 are used. In the steel plate cutting process, the steel plate 130A is cut by pressing the cutting blades against the strip-shaped steel plate 130A being unwound from the roll in the thickness direction of the steel plate 130A. In the steel plate cutting process, the distance between the cutting lines 139 in the length direction of the steel plate 130A is changed by adjusting the feed amount of the strip-shaped steel plate 130A.

[0116] In this modified example, the cutting line 139 has a convex shape 139a that protrudes from one side in the length direction of the strip-shaped steel plate 130A. That is, in this modified example, the cutting blade that cuts the steel plate 130A has a convex shape that protrudes from one side in the length direction of the steel plate 130A. Because the cutting line 139 has the convex shape 139a, a convex portion 130g is provided on one side located on one side in the length direction of the formed steel plate piece 130p, and a concave portion 130h is provided on one side located on the other side in the length direction.

[0117] 15 is a perspective view of the tooth 130 of this modified example. The steel plate pieces 130p formed through the cutting process of this modified example are stacked in the stacking direction D1 in the arrangement process, and are covered with the insulator portion 142 of the first resin portion 140 in the molding process. The convex portion 130g and the concave portion 130h of the steel plate pieces 130p are arranged on the surfaces facing one and the other circumferential sides of the tooth 130.

[0118] The protruding height of the convex portion 130g is sufficiently small compared to the thickness of the insulator portion 142. The convex portion 130g is entirely embedded inside the insulator portion 142. This allows the insulator portion 142 to ensure insulation between the convex portion 130g and the coil 63. Furthermore, a portion of the insulator portion 142 fits inside the recess 130h.

[0119] According to the present embodiment, the protrusions 130g are embedded in the insulator portion 142, and thereby face a portion of the insulator portion 142 in the axial direction Z. Similarly, a portion of the insulator portion 142 enters the recesses 130h, and thus the inner surfaces of the recesses 130h face a portion of the insulator portion 142 in the axial direction Z. Therefore, the protrusions 130g and the recesses 130h function as retaining portions that prevent the teeth 130 from moving in the axial direction Z relative to the insulator portion 142. In other words, the surfaces of the teeth 130 are provided with retaining portions that include at least the protrusions 130g or the recesses 130h. According to this modification, the teeth 130 and the first resin portion 140 can be fixed to each other with a simple structure.

[0120] In this modification, both the protrusions 130g and the recesses 130h are provided as retaining portions on the surfaces of the teeth 130. However, the retaining portions may have only one of the protrusions 130g or the recesses 130h. Furthermore, the retaining portions may have multiple protrusions 130g or multiple recesses 130h.

[0121] In this modified example, a case has been described in which a retaining portion (a convex portion 130g or a concave portion 130h) is provided on all of the steel plate pieces 130p that make up the tooth 130. In this case, even if all of the steel plate pieces 130p are not fixed to each other, it is possible to prevent all of the steel plate pieces 130p from falling out of the first resin portion 140. However, when multiple steel plate pieces 130p are fixed to each other by caulking or the like, it is sufficient that a retaining portion is provided on at least one of the steel plate pieces 130p.

[0122] Second Embodiment FIG. 16 is a perspective view of a stator 260 according to a second embodiment.

[0123] The stator 260 of the second embodiment differs from the above-described embodiments mainly in the configurations of the first resin portion 240 , the second resin portion 250 , and the bus bars 266 .

[0124] The same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0125] As in the above-described embodiment, the stator 260 of this embodiment includes a plurality of teeth 30, a plurality of coils 63, a first resin part 240, a second resin part 250, and a plurality of (three in this embodiment) bus bars 266.

[0126] As in the above-described embodiment, the plurality of teeth 30 are arranged in the circumferential direction. Coils 63 are attached to the teeth 30 via insulator portions 242 (described later). The plurality of coils 63 include U-phase, V-phase, and W-phase coils 63. A bus bar 266 is connected to the plurality of coils 63.

[0127] One of the three bus bars 266 connects the U-phase coil 63 and the V-phase coil 63, another connects the V-phase coil 63 and the W-phase coil 63, and the remaining one connects the V-phase coil 63 and the W-phase coil 63. In this way, the three bus bars 266 connect the multiple coils 63 to form a delta connection. In other words, the multiple bus bars 266 electrically connect the coils 63 to each other.

[0128] The stator 260 of this embodiment is provided with three bus bars 266. The three bus bars 266 have the same shape. The three bus bars 266 are arranged symmetrically about the central axis J. Each of the three bus bars 266 has a base portion 266b extending along the axial direction and a pair of connection terminal portions 266c extending in parallel radially outward from the lower end of the base portion 266b. The upper end of the base portion 266b is connected to an external power supply. The connection terminal portions 266c are connected to the coil 63.

[0129] 17 is a diagram of a stator 260 of this embodiment, omitting the second resin portion 250. The first resin portion 240 of this embodiment has a plurality of insulator portions 242, a bottom wall portion 241, and a bus bar holding portion 245.

[0130] As in the above-described embodiment, the insulator portions 242 cover at least a portion of the outer surfaces of the teeth 30. The bottom wall portions 241 are disk-shaped and extend along a plane centered on the central axis J and perpendicular to the central axis J. The bottom wall portions 241 are connected to the lower ends of the insulator portions 242. As a result, the bottom wall portions 241 connect the multiple insulator portions 242 together.

[0131] The busbar holding portion 245 is located at the center of the bottom wall portion 241. The busbar holding portion 245 is located radially inward of the plurality of teeth 30. The busbar holding portion 245 protrudes upward from the upper surface of the bottom wall portion 241. The busbar holding portion 245 of this embodiment has a hexagonal prism shape extending along the axial direction Z.

[0132] A plurality of bus bars 266 are partially embedded in the bus bar holding portion 245. The base portion 266b extends upward from the upper surface of the bus bar holding portion 245. The connection terminal portion 266c extends radially outward from the surface of the bus bar holding portion 245 facing radially outward.

[0133] The first resin portion 240 of this embodiment is formed by insert molding, in which the plurality of teeth 30 and the plurality of bus bars 266 are embedded. That is, the first resin portion 240 of this embodiment holds the plurality of teeth 30 and the plurality of bus bars 266. Therefore, the first resin portion 240 can fix the plurality of teeth 30 to one another and the plurality of bus bars 266 to one another, and can also fix the teeth 30 to the bus bars 266 to one another. This makes it possible to omit the step of attaching the bus bars 266 to the coils 63, simplifying the manufacture of the stator 260 and enabling the stator 260 to be manufactured inexpensively.

[0134] 16 , the second resin part 250 covers at least a portion of the coils 63, at least a portion of the bus bars 266, and at least a portion of the first resin part 240. In this embodiment, the second resin part 250 is molded using a mold. The second resin part 250 is molded by insert molding, in which the coils 63, the bus bars 266, and the first resin part 240 are embedded.

[0135] In this embodiment, the thermal conductivity of the material making up the second resin part 250 is the same as that of the material making up the first resin part 240. However, the material making up the second resin part 250 may be different from the material making up the first resin part 240. In this case, similar to the first embodiment, it is preferable that the thermal conductivity of the material making up the second resin part 250 be higher than the thermal conductivity of the material making up the first resin part 240. According to this embodiment, the second resin part 250 can absorb heat from the embedded coil 63 and dissipate the heat to the atmosphere or other members.

[0136] The second resin part 250 has a disk shape centered on the central axis J. The second resin part 250 is located above the bottom wall part 241 of the first resin part 240. The second resin part 250 has a plurality of coils 63 embedded therein.

[0137] The second resin part 250 has a shaft 251. The shaft 251 extends upward from the upper surface of the portion of the second resin part 250 where the multiple coils 63 are embedded. The shaft 251 is cylindrical and extends in the axial direction Z around the central axis J. The inner ring of the first bearing 17 (see FIG. 1 ) of the rotor 10 fits into the shaft 251. As a result, the shaft 251 rotatably supports the rotor 10. According to this embodiment, since the second resin part 250 has the shaft 251, there is no need to prepare a separate member for the shaft. This reduces the number of parts of the stator 260 and reduces the manufacturing cost of the stator 260. Note that in this embodiment, the case where the shaft 251 is part of the second resin part 250 has been described. However, the shaft 251 may be part of another member, such as the first resin part 240.

[0138] The shaft 251 embeds the base portions 266b of the multiple bus bars 266. The upper ends of the base portions 266b protrude upward from the upper end surface of the shaft 251. The upper ends of the base portions 266b are inserted into and connected to, for example, a socket portion of an external power supply. By embedding the base portions 266b in the shaft 251, the shaft 251 supports the base portions 266b. Therefore, even if the upper ends of the base portions 266b are subjected to stress from the socket of the external power supply, it is possible to prevent the base portions 266b from falling over.

[0139] According to the stator 260 of this embodiment, at least some of the multiple bus bars 266 are embedded inside the shaft 251, which is part of the second resin part 250. According to this embodiment, by embedding the bus bars 266 inside the shaft 251, the bus bars 266 can be supported by the shaft 251.

[0140] [Third Embodiment] Fig. 18 is a perspective view of a motor 301 according to a third embodiment. Fig. 19 is a perspective view of a molded part 340M according to a third embodiment. Fig. 20 is an exploded perspective view of a plurality of teeth 30 and a back yoke 335 according to the third embodiment.

[0141] The same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0142] As shown in Fig. 18, the motor 301 of this embodiment has a pair of stators 360 and one rotor 310 disposed between the pair of stators 360. The pair of stators 360 of this embodiment face the rotor 310 in the axial direction Z with a gap therebetween. The motor 301 of this embodiment is a double-stator, single-rotor axial gap motor. Although not shown, the rotor 310 has a magnet group similar to that of the rotor 310 of the first embodiment (see Fig. 1).

[0143] The pair of stators 360 have the same structure. The pair of stators 360 are disposed inverted relative to each other in the axial direction Z. In the following description, the stator 360 will be described based on the posture of one of the pair of stators 360 that is located on the lower side.

[0144] A stator 360 of this embodiment includes a plurality of teeth 30 (see FIG. 19 ), a plurality of coils 63, a back yoke 335, and a first resin portion 340. The plurality of teeth 30 and the back yoke 335 are embedded in the first resin portion 340. In the following description, the plurality of teeth 30, the back yoke 335, and the first resin portion 340 in which they are embedded are referred to as a molded part 340M.

[0145] 20, the teeth 30 are arranged in the circumferential direction. As in the above-described embodiment, the teeth 30 are made of steel plate pieces 30p stacked in the radial direction.

[0146] The back yoke 335 is located below the multiple teeth 30. The back yoke 335 is annular and centered on the central axis J. The lower surfaces 30b of the multiple teeth 30 contact an upper surface 335f of the back yoke 335. Magnetic flux flowing downward from the lower surfaces 30b of the teeth 30 penetrates the back yoke 335. The back yoke 335 serves as a path for magnetic flux flowing between the multiple teeth 30, reducing magnetic resistance between the teeth 30.

[0147] The back yoke 335 of this embodiment is made of a strip-shaped steel plate 335B that is tightly wound in a spiral shape around the central axis J. The back yoke 335 has an inner circumferential surface 335d facing radially inward and an outer circumferential surface 335e facing radially outward.

[0148] In the following description, the steel plate 335B constituting the back yoke 335 will be referred to as a strip-shaped steel plate. In this embodiment, the strip-shaped steel plate 335B is a single continuous piece. The strip-shaped steel plate 335B has an inner peripheral end 335a, which is the end on the inner periphery, and an outer peripheral end 335b, which is the end on the outer periphery. The inner peripheral end 335a is located on an inner periphery surface 335d of the back yoke 335, and the outer peripheral end 335b is located on an outer periphery surface 335e of the back yoke 335.

[0149] 19 , the first resin portion 340 of this embodiment has a plurality of insulator portions 342 and a bottom wall portion 341. The insulator portions 342 cover at least a portion of the outer surface of the teeth 30. Meanwhile, the bottom wall portion 341 covers at least a portion of the back yoke 335. The bottom wall portion 341 is disk-shaped and extends along a plane perpendicular to the central axis J. The bottom wall portion 341 is connected to the lower ends of the insulator portions 342. As a result, the bottom wall portion 341 connects the plurality of insulator portions 342 together.

[0150] The bottom wall portion 341 is provided with a central hole 341h centered on the central axis J. The central hole 341h penetrates the bottom wall portion 341 in the axial direction Z. In the following description, the "inner edge of the bottom wall portion 341" refers to the inner circumferential surface of the bottom wall portion 341 that surrounds the central hole 341h, and the "outer edge of the bottom wall portion 341" refers to the outer circumferential surface of the bottom wall portion 341.

[0151] In this embodiment, a first recess 341a is provided on the inner edge of the bottom wall portion 341. The first recess 341a is recessed radially outward from the inner edge of the bottom wall portion 341. The multiple first recesses 341a are arranged at equal intervals along the circumferential direction. The inner peripheral surface 335d of the back yoke 335 is exposed at the bottom surface of the first recess 341a. Here, the bottom surface of the first recess 341a refers to the surface of the inner surface of the first recess 341a that faces radially inward.

[0152] The first recess 341a is positioned at a different position in the circumferential direction from the inner peripheral end 335a of the steel strip 335B. Therefore, the inner peripheral end 335a of the steel strip 335B is not exposed from the bottom surface of the first recess 341a and is covered by the first resin portion 340. Here, the portion of the inner edge of the bottom wall portion 341 that covers the inner peripheral end 335a of the steel strip 335B is referred to as a first covering portion 341c.

[0153] A plurality of second recesses 341b (three in this embodiment) are provided on the outer edge of the bottom wall portion 341. The second recesses 341b are recessed radially inward from the outer edge of the bottom wall portion 341. The second recesses 341b are arranged at equal intervals along the circumferential direction. The outer peripheral surface 335e of the back yoke 335 is exposed at the bottom surfaces of the second recesses 341b. Here, the bottom surface of the second recesses 341b refers to the surface of the inner surface of the second recesses 341b that faces radially outward.

[0154] The second recess 341b is disposed at a different position in the circumferential direction from the outer peripheral end 335b of the steel strip 335B. Therefore, the outer peripheral end 335b of the steel strip 335B is not exposed from the bottom surface of the second recess 341b and is covered by the first resin part 340. Here, the part of the outer edge of the bottom wall part 341 that covers the outer peripheral end 335b of the steel strip 335B is referred to as a second covering part 341d.

[0155] In this embodiment, the first resin portion 340 has a first covering portion 341c covering the inner peripheral end 335a of the strip-shaped steel plate 335B and a first covering portion 341c covering the outer peripheral end 335b. The spiral shape of the back yoke 335 is easily broken from the inner peripheral end 335a and the outer peripheral end 335b of the strip-shaped steel plate 335B. According to this embodiment, the inner peripheral end 335a and the outer peripheral end 335b of the strip-shaped steel plate 335B are covered by the first resin portion 340, thereby preventing the spiral shape of the back yoke 335 from breaking down from the ends. According to this embodiment, it is not necessary to fix the inner peripheral end 335a and the outer peripheral end 335b by a fixing method such as crimping or welding. This not only simplifies the manufacturing process of the stator 360, but also prevents deterioration of the magnetic properties of the strip-shaped steel plate 335B due to processes such as crimping or welding.

[0156] In this embodiment, an inner peripheral surface 335d and an outer peripheral surface 335e of the back yoke 335 are covered by the bottom wall portion 341 of the first resin portion 340. According to the stator 360 of this embodiment, the stator 360 can be fixed to a holding member such as a housing using the inner edge or outer edge of the bottom wall portion 341, which is a resin molding surface, as a reference. This makes it easy to manage dimensions and ensure coaxiality when fixing the stator 360 to a holding member.

[0157] In the present embodiment, the case has been described in which both end portions (inner peripheral end portion 335a and outer peripheral end portion 335b) of strip-shaped steel plate 335B are covered with first resin portion 340. However, if at least one of inner peripheral end portion 335a and outer peripheral end portion 335b is covered with first resin portion 340, deformation of the shape of back yoke 335 from that end portion can be suppressed. When only one end portion is covered with first resin portion 340, the other end portion may be fixed by a fixing means such as caulking or welding.

[0158] The first resin portion 340 of this embodiment is molded by insert molding, in which the back yoke 335 is embedded together with the multiple teeth 30. That is, the first resin portion 340 of this embodiment holds the multiple teeth 30 and the back yoke 335, and therefore can fix the multiple teeth 30 to one another and also fix the multiple teeth 30 to the back yoke 335 to one another. This makes it possible to omit the step of fixing the teeth 30 to the back yoke 335, simplifying the manufacturing process of the stator 360. Furthermore, this can stabilize the contact state between the teeth 30 and the back yoke 335, improving the functionality of the back yoke 335.

[0159] Furthermore, according to this embodiment, the back yoke 335 is formed by spirally winding a strip-shaped steel plate 335B. Therefore, compared to when steel plates are press-formed and laminated, no steel plate scraps are generated during manufacturing, and the yield of steel plates can be increased.

[0160] In this embodiment, the back yoke 335 is made of a strip-shaped steel plate 335B. However, the back yoke may be made of an annular thin steel plate with the axial direction Z as the thickness direction.

[0161] Next, a method for manufacturing the stator 360 of this embodiment will be described. In the following description, the same steps as those in the above-described embodiment will not be described.

[0162] The manufacturing method of the stator 360 of this embodiment includes a steel strip forming step, an arrangement step, a forming step, and an attachment step. In the manufacturing method of the stator 360 of this embodiment, the steel strip forming step, the arrangement step, the forming step, and the attachment step are performed in this order.

[0163] The manufacturing method of the stator 360 of this embodiment differs from the manufacturing method of the first embodiment mainly in that a strip steel plate forming process is performed before the placement process, that a back yoke 335 is placed in the cavity C in the placement process, and that the back yoke 335 is embedded with the first resin part 340 in the molding process.

[0164] In the manufacturing method of the stator 360 of this embodiment, it is preferable to perform a steel plate cutting step similar to that of the first embodiment described above before the arrangement step. Also, the attachment step is a step of assembling the multiple coils 63, bus bars, etc., similar to the above-described embodiment.

[0165] As shown in FIG. 20, the steel strip forming step is a step of forming the back yoke 335 by winding one steel strip 335B in a spiral shape with the thickness direction as the radial direction.

[0166] 21 is a schematic cross-sectional view taken along the radial direction of molds 391, 392 that mold the first resin portion 340 of this embodiment. The molds 391, 392 each have a first mold 391 and a second mold 392. The first mold 391 and the second mold 392 are arranged opposite each other in the axial direction Z. A cavity C is provided between the first mold 391 and the second mold 392. The cavity C includes a plurality of first spaces C1 and a second space C2. The first space C1 is a space for molding the insulator portion 342. The teeth 30 are arranged in the first space C1. The second space C2 is a space for molding the bottom wall portion 341. The back yoke 335 is arranged in the second space C2.

[0167] The second space C2 has an annular shape extending in the circumferential direction. The second die 392 has an inner inner surface that surrounds the second space C2 from the radially inner side and faces radially outward, and an outer inner surface that surrounds the second space C2 from the radially outer side and faces radially inward. The inner inner surface and the outer inner surface of the second die 392 face each other in the radial direction. The inner inner surface and the outer inner surface of the second die 392 each extend in the circumferential direction. The inner inner surface of the second die 392 is provided with a plurality of inner protrusions 392k. The inner protrusions 392k protrude radially outward. The multiple inner protrusions 392k are arranged at equal intervals in the circumferential direction. The outer inner surface is provided with a plurality of outer protrusions 392j. The outer protrusions 392j protrude radially inward. The multiple outer protrusions 392j are arranged at equal intervals in the circumferential direction.

[0168] The placement process is a process of placing the multiple teeth 30 and the back yoke 335 in the cavity C. The back yoke 335 is placed in the cavity C with the end faces (lower surfaces 30b) of the multiple teeth 30 facing the axial direction Z in contact with each other. In the placement process, the back yoke 335 is pressed against the lower surfaces 30b of the multiple teeth 30 using a pin or the like (not shown), so that the upper surface 335f of the back yoke 335 and the lower surfaces 30b of the multiple teeth 30 come into contact with each other.

[0169] In the placement process of this embodiment, the inner peripheral surface 335d of the back yoke 335 contacts the multiple inner convex portions 392k, and the outer peripheral surface 335e of the back yoke 335 contacts the multiple outer convex portions 392j. As a result, the back yoke 335 is held in the second space C2 of the cavity C and positioned with respect to the inner surfaces of the molds 391 and 392. Furthermore, the portion of the inner peripheral surface 335d of the back yoke 335 that contacts the inner convex portions 392k and the portion of the outer peripheral surface 335e that contacts the outer convex portions 392j are unlikely to come into contact with the molten resin material in the cavity C. Therefore, these portions are exposed from the bottom wall portion 341 of the first resin portion 340 after the first resin portion 340 is molded. Furthermore, a first recess 341a and a second recess 341b are formed on the inner and outer edges of the bottom wall portion 341 as traces of the inner convex portion 392k and the outer convex portion 392j, respectively.

[0170] According to the manufacturing method of this embodiment, in the molding process, the plurality of insulator portions 342 are molded, and the bottom wall portion 341 connecting the plurality of insulator portions 342 is also molded. Furthermore, in the molding process, by molding the bottom wall portion 341, the back yoke 335 is held by the first resin portion 340. Therefore, in the molding process, not only can the insulator portions 342 be molded, but also the plurality of teeth 30 can be fixed relative to one another and the plurality of teeth 30 can be fixed relative to the back yoke 335, thereby simplifying the manufacturing method.

[0171] [Devices Equipped with Motors] Next, examples of devices equipped with the motors 1 of the above-described embodiments will be described.

[0172] Here, the motor 1 shown in each drawing may be any of the motors in each embodiment, that is, may be a motor having any of the stators in each embodiment.

[0173] <Motorcycle> FIG. 22 is a side view of an electric motorcycle 3 having a motor 1. As shown in FIG.

[0174] The motor 1 is disposed inside the rear wheel 3a of the electric motorcycle 3. The motor 1 rotates the wheel 3a relative to the chassis of the electric motorcycle 3. The motor 1 may also be disposed inside the front wheel of the electric motorcycle. Furthermore, the motor 1 may also be disposed inside the wheel of a bicycle, electric four-wheel vehicle, wheelchair, etc.

[0175] <Unmanned Aerial Vehicle> FIG. 23 is a perspective view of an unmanned aerial vehicle 4 having a motor 1. As shown in FIG.

[0176] The unmanned aerial vehicle 4 of this embodiment has a main body 4a, an imaging device 4b, multiple (four in this embodiment) motors 1, and a propeller 4c connected to the rotor of each motor 1. Each motor 1 rotates the propeller 4c around its own central axis J.

[0177] <Electric Power Steering Apparatus> FIG. 24 is a schematic diagram of an electric power steering apparatus 5 having a motor 1. As shown in FIG.

[0178] The electric power steering device 5 is mounted on the steering mechanism of the wheels of an automobile. The electric power steering device 5 is a device that reduces steering force by hydraulic pressure. The electric power steering device 5 of this embodiment includes a motor 1, an oil pump 5a, a steering shaft 5b, and a control valve 5c. The steering shaft 5b transmits input from a steering wheel 5d to an axle 5f having wheels 5e. The oil pump 5a generates hydraulic pressure in a power cylinder 5g. The power cylinder 5g transmits hydraulic driving force to the axle 5f. The control valve 5c controls the oil in the oil pump 5a. In the electric power steering device 5, the motor 1 is mounted as a drive source for the oil pump 5a.

[0179] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to these examples. The shapes and combinations of the components shown in the above examples are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0180] The motor to which the present invention is applied can be applied to various devices. The motor can be applied to, for example, a rotating electric machine such as a generator. In this case, the motor may be a three-phase AC generator. The use of the motor is not particularly limited. The number of poles and the number of slots of the motor are not particularly limited. The coils in the motor may be configured in any winding method. The configurations described above in this specification can be combined as appropriate within a range that does not contradict each other.

[0181] The present technology can be configured as follows.

[0182] (1) A stator that faces axially a rotor that can rotate around a central axis, the stator comprising a plurality of teeth arranged circumferentially, coils attached to each of the plurality of teeth, and a first resin portion that holds the plurality of teeth, the first resin portion having an insulator portion positioned between the teeth and the coils.

[0183] (2) The stator described in (1), wherein the surfaces of the teeth are provided with exposed portions that are exposed from the insulator portions, and the exposed portions have exposed end faces located on the end faces of the teeth facing in the axial direction, and exposed outer surfaces that are connected to the exposed end faces and face in a direction perpendicular to the axial direction.

[0184] (3) The stator according to (2), wherein the teeth have a plurality of steel plate pieces stacked along a stacking direction, and the exposed outer surface has a pair of exposed surfaces provided on end surfaces on one side and the other side in the stacking direction.

[0185] (4) The stator according to (3), wherein the pair of exposed surfaces have linear portions that extend linearly along the axial direction.

[0186] (5) A stator according to any one of (1) to (4), wherein a retaining portion having a convex portion protruding in a circumferential direction or a concave portion recessed in a circumferential direction is provided on the surface of the tooth, and the retaining portion is covered by the insulator portion.

[0187] (6) The stator according to any one of (1) to (5), further comprising a back yoke held by the first resin portion and in contact with end faces of the plurality of teeth facing the axial direction.

[0188] (7) The stator according to (6), wherein the back yoke is formed by spirally winding a strip-shaped steel plate.

[0189] (8) The stator according to (7), wherein the first resin portion has a covering portion that covers an end portion of the strip-shaped steel plate.

[0190] (9) The stator according to any one of (1) to (8), further comprising a plurality of bus bars that electrically connect the coils to each other, the bus bars being held by the first resin portion.

[0191] (10) The stator according to any one of (1) to (9), further comprising a second resin portion covering at least a portion of the plurality of coils, the second resin portion having a shaft extending in the axial direction centered on the central axis.

[0192] (11) The stator according to any one of (1) to (10), further comprising: a plurality of bus bars electrically connecting the coils to each other; and a second resin portion covering at least a portion of the plurality of coils, wherein the second resin portion has a shaft extending in the axial direction centered on the central axis, and at least a portion of the plurality of bus bars is embedded inside the shaft.

[0193] (12) The stator according to any one of (1) to (11), further comprising a bus bar connecting the coils to each other, some of the plurality of coils having first connection portions connected to the bus bar, and the first connection portions of the coils connected by one bus bar being positioned in the same axial direction.

[0194] (13) The stator according to any one of (1) to (12), further comprising a plurality of bus bars connecting the plurality of coils together, the plurality of bus bars overlapping each other when viewed in the axial direction.

[0195] (14) The stator according to any one of (1) to (13), further comprising: a power supply line connected to an external power supply; and a bus bar connecting the coils to each other; some of the coils have first connection portions connected to the bus bar; some of the coils have second connection portions connected to the power supply line; and axial positions of at least one of the first connection portions and at least one of the second connection portions coincide with axial positions of lower ends of the coils.

[0196] (15) The stator according to (14), further comprising a shaft located radially inward of the plurality of teeth, the shaft having a hollow portion extending in the axial direction and opening at an end of the shaft, and a plurality of holes extending radially outward from the hollow portion, the plurality of holes being arranged to overlap within an axial range in which the plurality of bus bars are arranged.

[0197] (16) A stator according to any one of (1) to (15), further comprising a second resin part, wherein the first resin part has an outer wall part surrounding the plurality of teeth from the outside in the radial direction, an inner wall part located radially inside the plurality of teeth, and a bottom wall part connecting the outer wall part and the inner wall part and covering the plurality of coils from one axial side, wherein the second resin part is filled in a region surrounded by the outer wall part, the inner wall part, and the bottom wall part and covers at least a portion of the plurality of coils, and wherein the thermal conductivity of the material constituting the second resin part is higher than the thermal conductivity of the material constituting the first resin part.

[0198] (17) The stator according to (16), further including a metal shaft located radially inward of the plurality of teeth, wherein the second resin portion is in contact with the shaft.

[0199] (18) A motor having the stator according to any one of (1) to (17) and the rotor.

[0200] (19) A method for manufacturing a stator that faces axially with a rotor that can rotate around a central axis, the method comprising: an arrangement step of arranging multiple teeth in a cavity of a mold; a molding step of filling the cavity with resin to mold a first resin part, forming an insulator part on the surface of the teeth, and holding the multiple teeth with the first resin part; and an attachment step of attaching a coil to the teeth via the insulator part.

[0201] (20) A method for manufacturing a stator according to (19), wherein an inner surface of the mold is provided with an accommodating recess for accommodating the axial end portion of the tooth, and in the arrangement process and the molding process, the inner surface of the accommodating recess contacts the end face of the tooth facing the axial direction and the outer surface connected to the end face and facing a direction perpendicular to the axial direction.

[0202] (21) A method for manufacturing a stator described in (19) or (20), wherein the teeth have a plurality of steel plate pieces stacked along a stacking direction, and the inner surface of the mold is provided with a pair of pressing surfaces that contact the end faces of the teeth on one side and the other side in the stacking direction.

[0203] (22) The method for manufacturing a stator described in (21), wherein the mold has a pressing portion that is arranged on an inner surface surrounding the cavity that faces the stacking direction and is movable in the stacking direction, and the pressing portion has one of the pressing surfaces and presses the teeth against the other pressing surface.

[0204] (23) The method for manufacturing a stator according to any one of (19) to (22), further comprising a steel plate cutting step performed before the arranging step, wherein the steel plate cutting step is a step of cutting a strip-shaped steel plate along cutting lines extending along the width direction to form a plurality of steel plate pieces, and the arranging step is a step of stacking the plurality of steel plate pieces and arranging them in the cavity.

[0205] (24) The method for manufacturing a stator according to (23), wherein the cutting line has a convex shape that protrudes to one side in the length direction of the strip-shaped steel plate.

[0206] (25) A method for manufacturing a stator described in any one of (19) to (24), which includes a strip steel plate forming process carried out before the arranging process, wherein the strip steel plate forming process is a process of winding a single strip steel plate into a spiral shape with the thickness direction as the radial direction to form a back yoke, the arranging process is a process of arranging the back yoke in the cavity in a state where it is in contact with end faces of the multiple teeth facing in the axial direction, and the forming process is a process of holding the back yoke with the first resin portion.

[0207] 1,301...motor, 10,310...rotor, 30,130...teeth, 30p,130p...steel sheet pieces, 31...exposed portion, 32...exposed end surface, 33...exposed outer surface, 33a...first exposed surface (exposed surface), 33aa...first straight portion (straight portion), 33b...second exposed surface (exposed surface), 33ba...second straight portion (straight portion), 40,140,240,340...first resin portion, 41,241,341...bottom wall portion, 42,142,242,342...insulator portion, 43...inner wall portion, 44...outer wall portion, 50,250...second resin portion, 60,260,360...stator, 61,25 DESCRIPTION OF SYMBOLS 1...shaft, 61g...hole portion, 61h...hollow portion, 62...power supply line, 63...coil, 63Ua, 63Va, 63Wa...first connecting portion, 63Ub, 63Vb, 63Wc...second connecting portion, 66, 67, 68, 69, 266...bus bar, 90, 391, 392...mold, 92c...side surface, 92d...accommodating recess, 92f, 93f...pressing surface, 93...pressing portion, 130g...convex portion, 130A, 335B...steel plate, 139...cutting line, 139a...convex shape, 335...back yoke, C...cavity, D1...stacking direction, J...central axis line, R...range, Z...axial direction, θ...circumferential direction

Claims

1. A stator having a rotor rotatable about a central axis and axially opposed thereto, the stator comprising: a plurality of teeth arranged in a circumferential direction; coils respectively mounted on the plurality of teeth; and a first resin portion holding the plurality of teeth, wherein the first resin portion has an insulator portion located between the teeth and the coils.

2. An exposed portion exposed from the insulator portion is provided on the surface of the teeth, the exposed portion having an exposed end face located on an end face facing the axial direction of the teeth and an exposed outer face continuous with the exposed end face and facing a direction orthogonal to the axial direction. The stator according to claim 1.

3. The teeth have a plurality of steel plate pieces laminated along a lamination direction, and the exposed outer face has a pair of exposed faces provided on end faces on one side and the other side in the lamination direction. The stator according to claim 2.

4. The pair of exposed faces have a straight portion extending linearly along the axial direction. The stator according to claim 3.

5. A retaining portion having a convex portion protruding in the circumferential direction or a concave portion recessed in the circumferential direction is provided on the surface of the teeth, and the retaining portion is covered by the insulator portion. The stator according to claim 1.

6. The stator according to claim 1, further comprising a back yoke held by the first resin portion and contacting end faces of the plurality of teeth facing the axial direction.

7. The back yoke is formed by winding a strip-shaped steel plate in a spiral shape. The stator according to claim 6.

8. The first resin portion has a covering portion covering an end portion of the strip-shaped steel plate. The stator according to claim 7.

9. The stator according to claim 1, further comprising a plurality of bus bars electrically connecting the coils to each other, the bus bars being held by the first resin portion.

10. The stator according to claim 1, further comprising a second resin portion covering at least a part of the plurality of coils, the second resin portion having a shaft extending axially about the central axis.

11. The stator according to claim 1, further comprising a plurality of bus bars electrically connecting the coils to each other and a second resin portion covering at least a part of the plurality of coils, the second resin portion having a shaft extending axially about the central axis, and at least a part of the plurality of bus bars being embedded inside the shaft.

12. The stator according to claim 1, comprising a bus bar connecting the coils, wherein some of the plurality of coils have a first connection portion connected to the bus bar, and the first connection portions of the coils connected by one bus bar have the same axial position.

13. The stator according to claim 1, comprising a plurality of bus bars connecting the plurality of coils, wherein the plurality of bus bars overlap each other when viewed axially.

14. The stator according to claim 1, comprising a power line connected to an external power source and a bus bar connecting the coils, wherein some of the plurality of coils have a first connection portion connected to the bus bar, some of the plurality of coils have a second connection portion connected to the power line, and the axial positions of at least one of the first connection portions and at least one of the second connection portions coincide with the axial position of the lower end portion of the coil.

15. The stator according to claim 14, further comprising a shaft located radially inside the plurality of teeth, the shaft having a hollow portion extending axially and opening at an end of the shaft, and a plurality of hole portions extending radially outward from the hollow portion, wherein the plurality of hole portions are arranged to overlap an axial range in which the plurality of bus bars are arranged.

16. The stator according to claim 1, comprising a second resin portion, wherein the first resin portion has an outer wall portion surrounding the plurality of teeth from the radially outer side, an inner wall portion located radially inside the plurality of teeth, and a bottom wall portion connecting the outer wall portion and the inner wall portion and covering the plurality of coils from one axial side, the second resin portion is filled in a region surrounded by the outer wall portion, the inner wall portion, and the bottom wall portion and covers at least a part of the plurality of coils, and the thermal conductivity of the material constituting the second resin portion is higher than the thermal conductivity of the material constituting the first resin portion.

17. The stator according to claim 16, further comprising a metal shaft located radially inside the plurality of teeth, wherein the second resin portion is in contact with the shaft.

18. A motor having the stator according to any one of claims 1 to 17 and the rotor.

19. A method for manufacturing a stator having a rotor rotatable about a central axis and a stator axially opposed thereto, the method comprising: an arranging step of arranging a plurality of teeth in a cavity of a mold; a molding step of filling the cavity with resin to form a first resin portion, forming an insulator portion on the surface of the teeth, and holding the plurality of teeth with the first resin portion; and a mounting step of mounting a coil on the teeth via the insulator portion.

20. An inner surface of the mold is provided with a receiving recess for receiving an axial end portion of the teeth. In the arranging step and the molding step, an inner surface of the receiving recess contacts an end surface facing the axial direction of the teeth and an outer surface connected to the end surface and facing a direction orthogonal to the axial direction. The method for manufacturing a stator according to claim 19.

21. The teeth have a plurality of steel plate pieces laminated along a lamination direction. An inner surface of the mold is provided with a pair of pressing surfaces that contact end surfaces on one side and the other side of the teeth in the lamination direction. The method for manufacturing a stator according to claim 19.

22. The mold has a pressing portion disposed on a surface facing the lamination direction among inner surfaces surrounding the cavity and movable in the lamination direction. The pressing portion has one of the pressing surfaces and presses the teeth against the other pressing surface. The method for manufacturing a stator according to claim 21.

23. The method includes a steel plate cutting step performed before the arranging step. The steel plate cutting step is a step of cutting a strip-shaped steel plate along a cutting line extending in the width direction to form a plurality of steel plate pieces. The arranging step is a step of laminating the plurality of steel plate pieces and arranging them in the cavity. The method for manufacturing a stator according to claim 19.

24. The cutting line has a convex shape protruding from one side in the length direction of the strip-shaped steel plate. The method for manufacturing a stator according to claim 23.

25. The method includes a strip-shaped steel plate forming step performed before the arranging step. The strip-shaped steel plate forming step is a step of winding a single strip-shaped steel plate in a spiral shape with the thickness direction as the radial direction to form a back yoke. The arranging step is a step of arranging the back yoke in the cavity in a state of contacting end surfaces facing the axial direction of the plurality of teeth. The molding step is a step of holding the back yoke with the first resin portion. The method for manufacturing a stator according to claim 19.

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