Stator core and motor

Abstract

To provide a stator core and a motor capable of suppressing deterioration of magnetic characteristics.SOLUTION: A stator core 21 includes a yoke 4 and a teeth 5. The yoke 4 has an annular shape in a circumferential direction surrounding an axial center 30 of a rotor 3. The teeth 5 are formed separately from the yoke 4, and protrude from an inner peripheral surface 40 of the yoke 4 toward the axial center 30. The teeth 5 includes a teeth main body part 50 and a fitting part 51. The fitting part 51 has a protruding end surface 52 and two outer side surfaces 53 and 53. The yoke 4 has a recess part 41 into which the fitting part 51 is fitted. The recess part 41 has a bottom surface 42 and two inner surfaces 43, 43. Interference is set between the two outer surfaces 53, 53 and the two inner surfaces 43, 43. An angle θ formed between the inner surfaces 43 and 43 and the inner peripheral surface 40 is 15 degrees or more and 45 degrees or less.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a stator core and a motor, and more particularly to a stator core including a yoke and teeth separate from the yoke, and a motor including this stator core. [Background technology]

[0002] Patent Document 1 discloses a stator for a rotating electric machine having a stator core formed by press-fitting teeth into a conventional magnetic flux path yoke. In this stator, the press-fit portions of the teeth are press-fitted into press-fit grooves in the magnetic flux path yoke to form the stator core. The press-fit portions of the teeth and the press-fit grooves in the magnetic flux path yoke are wedge-shaped. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-115124 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the rotating electric machine described in Patent Document 1, the greater the angle formed by the inner surface of the press-fit groove with respect to the inner peripheral surface of the magnetic flux path yoke, the less round the magnetic flux path yoke becomes, and the more likely it is that the magnetic characteristics will deteriorate.

[0005] An object of the present disclosure is to provide a stator core and a motor that can suppress deterioration of magnetic properties. [Means for solving the problem]

[0006] A stator core according to one aspect of the present disclosure includes a yoke and teeth. The yoke is annular in the circumferential direction surrounding the axis of a rotor's rotating shaft. The teeth are formed separately from the yoke and protrude from the inner peripheral surface of the yoke toward the axis. The teeth have a tooth main body portion and a fitting portion. The fitting portion protrudes from the tooth main body portion toward the opposite side of the axis. The fitting portion has a protruding end face and two outer side faces. The protruding end face faces the opposite side of the axis. The two outer side faces are continuous with each other on both sides of the protruding end face in the circumferential direction and face outward in the circumferential direction. The length (W1) between the two outer side faces in the circumferential direction at the end opposite the axis is longer than the length (W2) between the two outer side faces in the circumferential direction at the end closest to the axis. The yoke has a recess. The recess is recessed from the inner peripheral surface toward the opposite side of the axis and fits into the fitting portion. The recess has a bottom surface and two inner side surfaces. The bottom surface faces the axis. The two inner side surfaces are continuous with each other on both sides of the bottom surface in the circumferential direction and face inward in the circumferential direction. The recess is formed so that the distance (L1) between the two inner side surfaces in the circumferential direction at the end opposite the axis is longer than the distance (L2) between the two inner side surfaces in the circumferential direction at the end on the axis side. An interference is set between the two outer side surfaces and the two inner side surfaces. The angle formed by the inner side surfaces with respect to the inner circumferential surface is 15 degrees or more and 45 degrees or less.

[0007] A motor according to one aspect of the present disclosure includes a stator and the rotor, wherein the stator has the stator core and a winding wound around the stator core. [Effects of the Invention]

[0008] The stator core and motor of the present disclosure can suppress deterioration of magnetic properties. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view of a motor according to a first embodiment. [Figure 2] FIG. 2 is a perspective view of a stator of the motor. [Figure 3] Fig. 3A is a front view of the yoke of the stator of the same, and Fig. 3B is a partially enlarged view of Fig. 3A. [Figure 4] Fig. 4A is a front view of the teeth of the stator of the same, and Fig. 4B is a partially enlarged view of Fig. 4A. [Figure 5] FIG. 5 is a partially enlarged front view illustrating the dimensional relationship between the teeth and the yoke of the above. [Figure 6] FIG. 6 is a graph showing the relationship line between the angle and the deformation amount of the yoke, and the tangent line to that relationship line. [Figure 7] FIG. 7 is a graph showing the relationship between the angle and the difference between the relation line and its tangent line. [Figure 8] FIG. 8 is an enlarged cross-sectional view of a part of a yoke of a motor according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] (1) Overview A stator core and a motor according to the present disclosure will be described. The embodiments described below are merely a part of various embodiments of the present disclosure, and various modifications can be made depending on the design and the like as long as the object of the present disclosure can be achieved in the following embodiments.

[0011] As shown in FIGS. 1 and 2 , a stator core 21 according to the present disclosure includes a yoke 4 and teeth 5. The yoke 4 is annular in the circumferential direction 10 surrounding the axis 30 of the rotor 3. The teeth 5 are formed separately from the yoke 4 and protrude from the inner peripheral surface 40 of the yoke 4 toward the axis 30. The teeth 5 include a tooth main body portion 50 and a fitting portion 51. The fitting portion 51 includes a protruding end face 52 and two outer side surfaces 53, 53. The protruding end face 52 faces away from the axis 30. The two outer side surfaces 53, 53 are continuous with each other on both sides of the protruding end face 52 in the circumferential direction 10 and face outward in the circumferential direction 10. The yoke 4 is formed such that a length W1 between the two outer side surfaces 53, 53 in the circumferential direction 10 at the end opposite the axis 30 is longer than a length W2 between the two outer side surfaces 53, 53 in the circumferential direction 10 at the end closer to the axis 30. The yoke 4 has a recess 41. The recess 41 is recessed from the inner circumferential surface 40 toward the side opposite the axis 30, and the fitting portion 51 is fitted into the recess 41. The recess 41 has a bottom surface 42 and two inner side surfaces 43, 43. The bottom surface 42 faces toward the axis 30. The two inner side surfaces 43, 43 are continuous with each other on both sides of the bottom surface 42 in the circumferential direction 10 and face inward in the circumferential direction 10. The yoke 4 is formed such that a distance L1 between the two inner side surfaces 43, 43 in the circumferential direction 10 at the end opposite the axis 30 is longer than a distance L2 between the two inner side surfaces 43, 43 in the circumferential direction 10 at the end closer to the axis 30. An interference is set between the two outer side surfaces 53, 53 and the two inner side surfaces 43, 43. The angle θ formed by the inner side surfaces 43, 43 with respect to the inner circumferential surface 40 is equal to or greater than 15 degrees and equal to or less than 45 degrees.

[0012] Moreover, the motor 1 according to the present disclosure includes a stator 2 and a rotor 3. The stator 2 has a stator core 21 and a winding 22 wound around the stator core 21.

[0013] In the above-described stator core 21 and motor 1, deterioration of the magnetic characteristics can be suppressed.

[0014] (2) First embodiment The stator 2 has a stator core 21 and a winding 22 wound around the stator core 21 .

[0015] (2.1) Stator core (2.1.1) York The stator core 21 includes a yoke 4 and teeth 5. As shown in FIG. 1, the yoke 4 has an annular shape in the circumferential direction 10 surrounding the axis 30 of the rotating shaft 31 of the rotor 3. In this embodiment, as shown in FIG. 3A, the yoke 4 has an annular shape when viewed in the direction in which the axis 30 extends (hereinafter referred to as the axial direction), and the center of the yoke 4 coincides with the axis 30 of the rotating shaft 31 of the rotor 3. The yoke 4 includes a plurality of steel plates stacked in the axial direction. The steel plates are formed of, for example, electromagnetic steel plates such as silicon steel plates. As shown in FIGS. 3A and 3B, the yoke 4 has recesses 41. The recesses 41 are recessed from the inner circumferential surface 40 toward the opposite side of the axis 30 (the outer side in the radial direction, hereinafter referred to as the "diametrically outer side") and serve as fitting portions into which the teeth 5 are fitted. In this embodiment, the recesses 41 are notches penetrating in the axial direction. A plurality of recesses 41 (18 in this embodiment) are formed on inner circumferential surface 40 at equal intervals in circumferential direction 10. Note that the inner surfaces of recesses 41 are not included in inner circumferential surface 40 of yoke 4.

[0016] 3B, the recess 41 has a bottom surface 42 and two inner side surfaces 43, 43. The bottom surface 42 faces the axis 30 (the radially inner side, hereinafter referred to as the "radially inner side"). The two inner side surfaces 43, 43 are continuous with each other on both sides of the bottom surface 42 in the circumferential direction 10 and face inward in the circumferential direction 10.

[0017] The depth D1 is the distance from the inner circumferential surface 40 to the bottom surface 42. The depth D1 is, for example, 2.82 mm, but is not particularly limited to this size.

[0018] The recess 41 is formed in a so-called wedge shape when viewed in the axial direction. The recess 41 is formed so that a distance L1 between the two inner side surfaces 43, 43 at the radially outer end in the circumferential direction 10 is longer than a distance L2 between the two inner side surfaces 43, 43 at the radially inner end in the circumferential direction 10. The distance L1 is, for example, 9.42 mm, and the distance L2 is, for example, 7.51 mm, but the sizes are not particularly limited.

[0019] The bottom surface 42 has a flat surface at its intermediate portion in the circumferential direction 10. The two inner side surfaces 43, 43 each have a flat surface at their intermediate portions in the radially inward and outward directions.

[0020] Second rounded corners 44 having a second radius of curvature R2 (see FIG. 5 ) smaller than a first radius of curvature R1 (described later) are formed at the radially outer ends of the two inner surfaces 43, 43 and at the end of the bottom surface 42 in the circumferential direction 10. The second rounded corners 44 have a so-called R-shape. The second radius of curvature R2 is, for example, 0.35 mm, but the size is not particularly limited.

[0021] A fourth rounded corner 45 having a fourth radius of curvature R4 (see FIG. 5) larger than a third radius of curvature R3 (described later) is formed at the radially inner end of each of the two inner surfaces 43, 43. The fourth rounded corner 45 has a so-called R-shape. The fourth radius of curvature R4 is, for example, 0.45 mm, but the size is not particularly limited.

[0022] By forming the second rounded corners 44 and the fourth rounded corners 45, the occurrence of stress concentration in the yoke 4 can be suppressed.

[0023] (2.1.2) Teeth As shown in Fig. 1, the teeth 5 are formed separately from the yoke 4 and protrude from the inner peripheral surface 40 of the yoke 4 toward the axis 30. The teeth 5 are formed from the same electromagnetic steel sheet as the yoke 4. In this embodiment, a plurality of the teeth 5 (18 in this embodiment) are formed on the inner peripheral surface 40 of the yoke 4 at equal intervals in the circumferential direction 10.

[0024] As shown in FIG. 4A , the tooth 5 has a tooth main body portion 50 and a fitting portion 51. The tooth main body portion 50 is a portion that protrudes radially inward from the inner circumferential surface 40 of the yoke 4 (including an imaginary surface of an extension of the inner circumferential surface 40). The tooth main body portion 50 is formed so that its length in the circumferential direction 10 is W3. The winding 22 is wound around the tooth main body portion 50 (see FIGS. 1 and 2 ). The radially inner end of the tooth main body portion 50 protrudes in the circumferential direction 10 to prevent the winding 22 wound around the tooth main body portion 50 from falling off. That is, the radially outer end and the radially inner / outer middle portion of the tooth main body portion 50 have a length in the circumferential direction 10 of W3, while the length in the circumferential direction 10 of the radially inner end is longer than W3.

[0025] As shown in Fig. 4B, the fitting portion 51 is a protruding portion that protrudes radially outward from the tooth main body portion 50. The fitting portion 51 has a protruding end face 52 and two outer side faces 53, 53. The protruding end face 52 faces radially outward. The two outer side faces 53, 53 are continuous with each other on both sides of the protruding end face 52 in the circumferential direction 10 and face outward in the circumferential direction 10.

[0026] The height from the tooth main body 50 to the protruding end surface 52 is defined as a protruding height H1. The protruding height H1 is, for example, 2.70 mm, but is not particularly limited to this size.

[0027] The fitting portion 51 is formed in a so-called wedge shape when viewed in the axial direction. The fitting portion 51 and the recess 41 are formed in approximately the same shape when viewed in the axial direction. The length W1 between the two outer side surfaces 53, 53 in the circumferential direction 10 of the radially outer end portion is formed to be longer than the length W2 between the two outer side surfaces 53, 53 in the circumferential direction 10 of the radially inner end portion. The protruding end surface 52 has a flat surface at its middle portion in the circumferential direction 10. The length W1 is, for example, 9.38 mm, and the length W2 is, for example, 7.49 mm, but the sizes are not particularly limited.

[0028] The two outer surfaces 53, 53 have radially inward and outward intermediate portions each formed by a flat surface.

[0029] First rounded corners 54 with a first radius of curvature R1 (see FIG. 5) are formed at the radially outer ends of the two outer surfaces 53, 53 and at the end of the protruding end surface 52 in the circumferential direction 10. The first rounded corners 54 have a so-called R-shape. The first radius of curvature R1 is, for example, 0.45 mm, but the size is not particularly limited.

[0030] A third rounded corner 55 having a third curvature radius R3 (see FIG. 5) is formed at the radially inner end of each of the two outer surfaces 53, 53. The third rounded corner 55 has a so-called R-shape. The third curvature radius R3 is, for example, 0.35 mm, but the size is not particularly limited.

[0031] By forming the first rounded corners 54 and the third rounded corners 55, the occurrence of stress concentration in the teeth 5 can be suppressed.

[0032] The teeth 5 are attached integrally to the yoke 4 by fitting the fitting portions 51 into the recesses 41 serving as fitted portions of the yoke 4 .

[0033] (2.2) Winding As shown in FIGS. 1 and 2, a conductor that constitutes the winding 22 is wound around the teeth 5. This forms the winding 22. In this embodiment, 18 windings 22 are provided on the stator core 21. The cross section of the conductor is rectangular. In particular, in this embodiment, the winding 22 is a so-called formed coil. The formed coil in this disclosure does not include a coil in which a conductor with a constant width and thickness is simply wound spirally.

[0034] The formed coil is formed, for example, by preparing a plurality of rectangular plate materials of different lengths, widths, or thicknesses and joining these plate materials by cold welding, welding, or other methods. The plate materials are made of a so-called low-resistivity material such as copper or aluminum.

[0035] Alternatively, the formed coil may be formed by so-called casting, in which copper or the like is melted and poured into a mold. Furthermore, the formed coil may be formed by bending a plate-shaped conductor wire, which has been formed in advance so that its width and thickness vary along the way, at a predetermined position. Alternatively, the formed coil may be formed by rolling a plate-shaped conductor wire with a constant width and thickness at a predetermined position, changing the width or thickness along the way, and then winding the wire into a spiral shape. In short, the formed coil is formed by adding another process to winding the conductor wire, or by a method other than simple winding.

[0036] (2.3) Insulator The stator 2 has an insulator (not shown). The insulator is interposed between the stator core 21 and the windings 22. The insulator is made of an insulating material. The insulator is divided into two halves in the axial direction, and is arranged so that each halve covers both end faces of the teeth 5 in the axial direction. The insulator ensures an appropriate insulation distance between the stator core 21 and the windings 22.

[0037] (2.4) Busbar As shown in FIG. 2, the stator 2 has bus bars 23. The bus bars 23 are connected to conductors. The bus bars 23 facilitate the flow of large currents. The bus bars 23 are electrically connected to the conductors of the corresponding windings 22 to form connections for the U, V, and W phases. The bus bars 23 are arranged radially outside the windings 22.

[0038] The stator core 21, the windings 22, the insulators, and the bus bars 23 form the stator 2.

[0039] (2.5) Motors and rotors As shown in Fig. 1, motor 1 includes stator 2 and rotor 3. Rotor 3 has a rotary shaft 31 and rotates around an axis 30 of rotary shaft 31. In motor 1, magnetic flux generated from a plurality of windings 22 in stator 2 (18 in Fig. 1) generates an electromagnetic force that rotates rotor 3.

[0040] The rotor 3 has a cylindrical rotor core 32, a plurality of magnets 33, and a rotating shaft 31. The rotating shaft 31 is held inside the rotor core 32. The magnets 33 are arranged in a polygonal shape.

[0041] (3) Dimensional relationship between yoke and teeth Next, the dimensional relationship between the yoke 4 and the teeth 5, particularly the dimensional relationship between the recessed portion 41 of the yoke 4 and the fitting portion 51 of the teeth 5, will be described with reference to FIG.

[0042] (3.1) Interference An interference is set between the inner surface 43 and the outer surface 53. The interference is determined by the distance between the inner surface 43 and the outer surface 53 when it is assumed that the fitting portion 51 is fitted into the recess 41 without deformation of the recess 41 and the fitting portion 51. In other words, the interference is determined by the dimensional relationship between the recess 41 and the fitting portion 51 before the fitting portion 51 is fitted into the recess 41. The interference is not constant in the radially inward and outward directions.

[0043] The interference T1 between the two outer surfaces 53, 53 and the two inner surfaces 43, 43 at the radially outer end is larger than the interference T2 between the two outer surfaces 53, 53 and the two inner surfaces 43, 43 at the radially inner end. The two inner surfaces 43, 43 and the two outer surfaces 53, 53 are in contact with each other at flat portions in the middle in the radially inner / outer direction. The interference T1 is the interference at the radially outer end of the flat surface where the two inner surfaces 43, 43 and the two outer surfaces 53, 53 are in contact with each other. Furthermore, the interference T2 is the interference at the radially inner end of the flat surface where the two inner surfaces 43, 43 and the two outer surfaces 53, 53 are in contact with each other.

[0044] The advantages of having the interference T1 at the radially outer end greater than the interference T2 at the radially inner end will be described below.

[0045] From the viewpoint of preventing the teeth 5 from falling off from the yoke 4, a certain amount of interference is required when fitting the fitting portion 51 into the recess 41. When the fitting portion 51 is fitted into the recess 41 with a certain amount of interference, the recess 41 and the fitting portion 51 are deformed. At this time, of the deformations of the recess 41 and the fitting portion 51, the deformation of the radially inner end has a greater effect on the magnetic properties of the stator 2 (particularly, the effect on the deterioration of the magnetic properties) than the deformation of the radially outer end.

[0046] Therefore, the interference T1 between the two inner surfaces 43, 43 and the two outer surfaces 53, 53 is secured throughout the entire radial direction, while the interference T2 at the radially inner end is reduced, thereby suppressing deterioration of the magnetic properties due to deformation of the radially inner end of the recess 41 and the fitting portion 51.

[0047] In this embodiment, the ratio (T1 / W1) of the interference T1 at the radially outer end to the length W1 between the two outer surfaces 53, 53 at the radially outer end is set to be 0.15% or more and 1.3% or less. Furthermore, the ratio (T2 / L2) of the interference T2 at the radially inner end to the distance L2 between the two inner surfaces 43, 43 in the circumferential direction 10 at the radially inner end is set to be 0.10% or more and 1.0% or less. This allows the recesses 41 to obtain an appropriate tightening force on the fitting portion 51 when the yoke 4 and the teeth 5 are formed from electromagnetic steel sheets.

[0048] In this embodiment, the ratio (T1 / T2) of the interference T1 at the radially outer end to the interference T2 at the radially inner end is set to be 140% or more and 200% or less. If the ratio (T1 / T2) is less than 140%, it is difficult to make the interference T2 at the radially inner end sufficiently small. If the ratio (T1 / T2) exceeds 200%, the distribution of the interference in the radially inner and outer directions becomes more non-uniform, making it more likely that localized deformation will occur. Therefore, if the ratio (T1 / T2) is 140% or more and 200% or less, it is easy to make the interference T2 at the radially inner end sufficiently small, and it is possible to suppress localized deformation of the yoke 4 and the teeth 5.

[0049] Furthermore, by making the first curvature radius R1 larger than the second curvature radius R2 and making the third curvature radius R3 smaller than the fourth curvature radius R4, the fitting portion 51 can be better fitted into the recess 41.

[0050] (3.2) Gap Next, the gap between the bottom surface 42 and the protruding end surface 52 will be described.

[0051] A gap is set between the bottom surface 42 and the protruding end surface 52. The gap is a portion formed between the bottom surface 42 and the protruding end surface 52 when it is assumed that the fitting portion 51 is fitted into the recess 41 without deformation of the recess 41 and the fitting portion 51. In other words, the gap is determined by the dimensional relationship between the recess 41 and the fitting portion 51 before the fitting portion 51 is fitted into the recess 41. A protruding height H1 from the tooth main body portion 50 to the protruding end surface 52 is formed to be smaller than a depth D1 from the inner circumferential surface 40 to the bottom surface 42, thereby forming a gap between the bottom surface 42 and the protruding end surface 52.

[0052] The advantages of providing a gap between the bottom surface 42 and the protruding end surface 52 will be described. A certain amount of interference is required when fitting the fitting portion 51 into the recess 41, and as described above, deformation at the radially inner end has a greater effect on the magnetic characteristics of the stator 2 than deformation at the radially outer end. Reducing the interference T2 at the radially inner end requires increasing the interference T1 at the radially outer end. This tends to increase deformation at the radially outer end of the recess 41 and the fitting portion 51. However, if the fitting portion 51, compressed in the circumferential direction 10, can escape radially outward due to the large interference T1, deformation at the radially outer end of the recess 41 and the fitting portion 51 can be suppressed. Therefore, by providing a gap between the bottom surface 42 and the protruding end surface 52, the fitting portion 51, compressed in the circumferential direction 10, can escape to the radially outer gap, thereby suppressing deformation at the radially outer end of the recess 41 and the fitting portion 51. After fitting the fitting portion 51 into the recess 41, it is not necessary for a gap to be formed between the bottom surface 42 and the protruding end surface 52. That is, with the fitting portion 51 fitted into the recess 41, a gap may be formed between the bottom surface 42 and the protruding end surface 52, or a gap may not be formed between the bottom surface 42 and the protruding end surface 52. Even if a gap is formed between the bottom surface 42 and the protruding end surface 52, making it difficult for magnetic flux to form a magnetic circuit, the deformation of the radially outer end portion does not have a large effect on the magnetic characteristics of the stator 2 to begin with, and therefore deterioration of the magnetic characteristics is suppressed.

[0053] If the radial length of the gap is defined as gap height G1, the gap height G1 is expressed as the value (D1-H1) obtained by subtracting the protruding height H1 from the depth D1. In this embodiment, the ratio (G1 / H1) of the gap height G1 to the protruding height H1 is set to be 2% or more and 5% or less. By setting the ratio (G1 / H1) to be 2% or more, the fitting portion 51 compressed in the circumferential direction 10 can easily escape to the gap on the radially outer side. Furthermore, by setting the ratio (G1 / H1) to be 5% or less, a gap is less likely to be formed between the bottom surface 42 and the protruding end surface 52 after the fitting portion 51 is fitted into the recess 41, and deterioration of the magnetic properties is further suppressed.

[0054] Furthermore, in this embodiment, the gap is not constant in the circumferential direction 10. The gap height G1 at the center in the circumferential direction 10 is set to be smaller than the gap height G1 at the end in the circumferential direction 10. With regard to the deformation of the fitting portion 51 compressed in the circumferential direction 10, the amount of deformation at the end in the circumferential direction 10 is larger than the amount of deformation at the center in the circumferential direction 10. For this reason, it is preferable to set the gap height G1 at the center in the circumferential direction 10 to be smaller than the gap height G1 at the end in the circumferential direction 10.

[0055] When making the gap height G1 at the center in the circumferential direction 10 smaller than the gap height G1 at the end in the circumferential direction 10, the protrusion height H1 at the center in the circumferential direction 10 is made larger than the protrusion height H1 at the end in the circumferential direction 10. In this case, the depth D1 of the recess 41 may be constant in the circumferential direction 10 or may vary in the circumferential direction 10. For example, with regard to the depth D1 of the recess 41, the depth D1 at the center in the circumferential direction 10 may be smaller than the depth D1 at the end in the circumferential direction 10.

[0056] Furthermore, when making the gap height G1 at the center in the circumferential direction 10 smaller than the gap height G1 at the end in the circumferential direction 10, the depth D1 at the center in the circumferential direction 10 may be smaller than the depth D1 at the end in the circumferential direction 10. In this case, the gap height G1 of the fitting portion 51 may be constant in the circumferential direction 10 or may vary in the circumferential direction 10. For example, with regard to the gap height G1 of the fitting portion 51, the gap height G1 at the center in the circumferential direction 10 may be larger than the gap height G1 at the end in the circumferential direction 10.

[0057] This allows the gap height G1 to be changed in accordance with the distribution of deformation of the fitting portion 51 in the circumferential direction 10, making it easier for the fitting portion 51 to escape radially outward and making it less likely for a gap to form between the bottom surface 42 and the protruding end surface 52.

[0058] (3.3) Angle of the fitting part relative to the tooth body 3B , when fitting portion 51 is not fitted into recess 41, angle θ1 formed by inner side surfaces 43, 43 with respect to inner circumferential surface 40 is a predetermined angle of 15 degrees or more and 45 degrees or less. Note that inner circumferential surface 40 is cylindrical, and angle θ1 formed by inner side surfaces 43, 43 with respect to inner circumferential surface 40 is the angle formed between a tangent plane of cylindrical inner circumferential surface 40 that is tangent to inner circumferential surface 40 at a line of intersection with an imaginary extension of inner side surface 43, and the imaginary extension of inner side surface 43; angles θ2 and θ, which will be described later, are based on the same logic.

[0059] Also, as shown in Figure 4B, when the fitting portion 51 is not fitted into the recess 41, the angle θ2 formed by the outer surfaces 53, 53 with respect to the outer peripheral surface 500 of the tooth main body portion 50 is a predetermined angle similar to the angle θ1, which is greater than or equal to 15 degrees and less than or equal to 45 degrees.

[0060] As shown in Figure 5, when the fitting portion 51 is fitted into the recess 41, the inner surface 43 and the outer surface 53 are in contact with each other with almost no gap. When the fitting portion 51 is fitted into the recess 41, the angle θ formed by the inner surfaces 43, 43 of the yoke 4 with respect to the inner circumferential surface 40 is the same as the angle formed by the outer surfaces 53, 53 of the teeth 5 with respect to the outer circumferential surfaces 500, and this angle θ is a predetermined angle greater than or equal to 15 degrees and less than or equal to 45 degrees. The angle θ is substantially the same as the angles θ1 and θ2. In other words, the yoke 4 and the teeth 5 are deformed when the fitting portion 51 is fitted into the recess 41, but the changes in the angles θ1 and θ2 due to this deformation are slight and can be ignored.

[0061] In Fig. 6, the relationship between the angle θ (deg) and the deformation (mm) of the yoke 4 is shown by a solid line. Also in Fig. 6, the straight line connecting the point on the relationship line (solid line) at 30 (deg) and the origin (however, only the section from 15 (deg) to 60 (deg) is shown) is shown by a dashed line. Also in Fig. 7, the difference line between the angle θ (deg) and the difference between the relationship line (solid line in Fig. 6) and the straight line (dashed line in Fig. 6) is shown by a solid line.

[0062] 7, it can be seen that in the region where the angle θ is greater than or equal to 20 degrees and less than or equal to 40 degrees, the value of the difference line is sufficiently small, and deformation of the yoke 4 is sufficiently suppressed. Furthermore, in the region where the angle θ is greater than or equal to 15 degrees and less than or equal to 45 degrees, deformation of the yoke 4 is suppressed within an allowable range.

[0063] When the angle θ formed by the inner surfaces 43, 43 with respect to the inner circumferential surface 40 is equal to or greater than 15 degrees and equal to or less than 45 degrees, deformation of the yoke 4 is suppressed, and deterioration of the magnetic characteristics of the motor 1 is suppressed. The reason for this will be explained.

[0064] The recess 41 is formed on the inner portion of the yoke 4 in the thickness direction (diametrical inward / outward direction), but not on the outer portion. When the fitting portion 51 is fitted into the recess 41, the compressive stress in the circumferential direction 10 increases in the inner portion of the yoke 4 where the recess 41 is formed, but the compressive stress in the circumferential direction 10 does not increase in the outer portion where the recess 41 is not formed. Therefore, in the vicinity of where the fitting portion 51 of the yoke 4 is fitted, a bending moment occurs that causes the inner portion to stretch in the circumferential direction 10 relative to the outer portion of the yoke 4 in the thickness direction, reducing the circularity of the yoke 4.

[0065] Here, in terms of the relationship between the recess 41 and the mating portion 51, the larger the angle θ1 (angle θ2, θ) formed by the inner surfaces 43, 43 (outer surfaces 53, 53) with respect to the inner circumferential surface 40 (outer circumferential surface 500), the more the compressive force acting between the inner surface 43 and the outer surface 53 is directed toward the circumferential direction 10, thereby increasing the bending moment described above and further reducing the circularity of the yoke 4.

[0066] In contrast, as the angle θ1 (angles θ2, θ) formed by the inner surfaces 43, 43 (outer surfaces 53, 53) with respect to the inner peripheral surface 40 (outer peripheral surface 500) becomes smaller, the compressive force acting between the inner surface 43 and the outer surface 53 is directed more inward and outward in the radial direction, thereby reducing the bending moment described above and suppressing deterioration in the roundness of the yoke 4. Furthermore, since a gap is provided between the bottom surface 42 of the recess 41 and the protruding end surface 52 of the fitting portion 51, when a compressive force acting more inward and outward in the radial direction is applied between the inner surface 43 and the outer surface 53, deformation of the recess 41 and the fitting portion 51 is absorbed by the gap, and deformation of the yoke 4 is suppressed.

[0067] Experiments have shown that if the angle θ formed by the inner side surfaces 43, 43 with respect to the inner circumferential surface 40 is a predetermined angle of 15 degrees or more and 45 degrees or less, a motor 1 can be configured in which a practical degradation of magnetic properties is acceptable. It is more preferable that the angle θ formed by the inner side surfaces 43, 43 with respect to the inner circumferential surface 40 is 20 degrees or more and 40 degrees or less. This further suppresses the degradation of the roundness of the yoke 4, and further suppresses the degradation of the magnetic properties of the motor 1.

[0068] (3.4) Circumferential length Next, the length of the fitting portion in the circumferential direction 10 will be described. The value W3-W2, obtained by subtracting the length W2 between the two outer surfaces 53, 53 at the radially inner end of the fitting portion 51 from the length W3 of the tooth main body portion 50 in the circumferential direction 10, is the length of the portion of the tooth main body portion 50 where the fitting portion 51 does not protrude and is exposed radially outward in the circumferential direction 10. This portion comes into contact with the inner circumferential surface 40 of the yoke 4 and contributes to the formation of a magnetic circuit by the magnetic flux passing through this portion. Therefore, from the viewpoint of suppressing deterioration of the magnetic properties, it is preferable to increase the value W3-W2, and it is preferable that the ratio ((W3-W2) / W3) of the value W3-W2 to the length W3 of the tooth main body portion 50 in the circumferential direction 10 of the tooth main body portion 50 be 40% or more.

[0069] Increasing the value W3-W2 reduces the length W2 between the two outer side surfaces 53, 53 at the radially inner end in the circumferential direction 10. The length W2 between the two outer side surfaces 53, 53 at the radially inner end in the circumferential direction 10 provides a pressing margin for the fitting portion 51 when fitting the fitting portion 51 into the recess 41, so a certain amount of length W2 is necessary, and the ratio (W2 / W3) to the length W3 needs to be at least 20%. Therefore, the ratio ((W3-W2) / W3) is 40% or more and 80% or less. This makes it possible to ensure a pressing margin for the fitting portion 51 when fitting the fitting portion 51 into the recess 41 while suppressing deterioration of the magnetic properties.

[0070] (4) Variations Next, modified examples are listed below. The following modified examples may be realized in appropriate combination.

[0071] The shape of the yoke 4 when viewed in the axial direction does not have to be annular and is not limited thereto.

[0072] The number of teeth 5 and windings 22 formed on the stator core 21 is not limited.

[0073] The stator core 21 (yoke 4, teeth 5) may be made of a material other than an electromagnetic steel sheet.

[0074] The winding 22 does not have to be a formed coil. The cross-sectional shape of the conductive wire that constitutes the winding 22 is not limited to a rectangular shape, and may be a circular shape.

[0075] The insulator and the bus bar 23 are optional components in the present disclosure and may not be provided on the stator 2.

[0076] The recesses 41 of the yoke 4 do not have to be formed at equal intervals on the inner circumferential surface 40 in the circumferential direction 10. The recesses 41 do not have to be formed in a wedge shape.

[0077] The second rounded corners 44 may not be formed at the radially outer ends of the two inner side surfaces 43, 43 of the yoke 4 and at the end of the bottom surface 42 in the circumferential direction 10, and the fourth rounded corners 45 may not be formed at the radially inner ends of the two inner side surfaces 43, 43. In this case, the bottom surface 42 and the two inner side surfaces 43, 43 are each entirely flat. However, the bottom surface 42 and the two inner side surfaces 43, 43 are not limited to being flat.

[0078] The first rounded corners 54 may not be formed at the radially outer ends of the two outer side surfaces 53, 53 of the tooth 5 and at the circumferential end 10 of the protruding end surface 52, and the third rounded corners 55 may not be formed at the radially inner ends of the two outer side surfaces 53, 53. In this case, the protruding end surface 52 and the two outer side surfaces 53, 53 are each entirely flat. Note that the protruding end surface 52 and the two outer side surfaces 53, 53 are not limited to being flat.

[0079] The gap between the bottom surface 42 and the protruding end surface 52 may be constant in the circumferential direction 10 .

[0080] The interference T1 between the two outer surfaces 53, 53 and the two inner surfaces 43, 43 at the end opposite the axis 30 may be smaller than the interference T2 at the end on the axis 30 side, or may be the same as the interference T2.

[0081] The protruding height H1 from the tooth main body 50 to the protruding end face 52 may be greater than the depth D1 from the inner circumferential surface 40 to the bottom face 42, or may be the same as the depth D1.

[0082] As shown in Fig. 8, the yoke 4 may be configured from a plurality of segments 400 separated in the circumferential direction 10. A yoke 4 configured from a plurality of segments 400 is prone to deformation. For this reason, by setting the angle θ between the inner surfaces 43, 43 of the recess 41 of the yoke 4 and the inner circumferential surface 40 to be 15 degrees or more and 45 degrees or less, as in the present disclosure, the effects of suppressing deterioration in the roundness of the yoke 4 and suppressing deterioration in the magnetic characteristics of the motor 1 can be more significantly achieved.

[0083] (5) Summary As is clear from the above-described embodiment and its modified examples, the stator core (21) of the first aspect includes a yoke (4) and teeth (5). The yoke (4) is annular in the circumferential direction (10) surrounding the axis (30) of the rotating shaft (31) of the rotor (3). The teeth (5) are formed separately from the yoke (4) and protrude from the inner peripheral surface (40) of the yoke (4) toward the axis (30). The teeth (5) have a tooth main body portion (50) and a fitting portion (51). The fitting portion (51) protrudes from the tooth main body portion (50) toward the opposite side of the axis (30). The fitting portion (51) has a protruding end face (52) and two outer side faces (53, 53). The protruding end face (52) faces away from the axis (30). The two outer surfaces (53, 53) are continuous with each other on both sides of the protruding end surface (52) in the circumferential direction (10) and face outward in the circumferential direction (10). The length (W1) between the two outer surfaces (53, 53) in the circumferential direction (10) at the end opposite the axis (30) is longer than the length (W2) between the two outer surfaces (53, 53) in the circumferential direction (10) at the end closer to the axis (30). The yoke (4) has a recess (41). The recess (41) is recessed from the inner circumferential surface (40) toward the opposite side of the axis (30) and receives the mating portion (51). The recess (41) has a bottom surface (42) and two inner surfaces (43, 43). The bottom surface (42) faces the axis (30). The two inner surfaces (43, 43) are continuous on both sides of the bottom surface (42) in the circumferential direction (10) and face inward in the circumferential direction (10). The distance (L1) between the two inner surfaces (43, 43) in the circumferential direction (10) at the end opposite the axis (30) is longer than the distance (L2) between the two inner surfaces (43, 43) in the circumferential direction (10) at the end closer to the axis (30). An interference is set between the two outer surfaces (53, 53) and the two inner surfaces (43, 43). The angle (θ) formed by the inner surfaces (43, 43) with respect to the inner circumferential surface (40) is 15 degrees or more and 45 degrees or less.

[0084] According to the first aspect, the interference between the two inner surfaces (43, 43) and the two outer surfaces (53, 53) is ensured throughout the entire radial inward and outward direction, while deterioration of the magnetic characteristics of the motor (1) due to deformation of the radially inner ends of the recess (41) and the fitting portion (51) can be suppressed.

[0085] The second aspect can be realized by combining with the first aspect. In the second aspect, the angle (θ) is equal to or greater than 20 degrees and equal to or less than 40 degrees.

[0086] According to the second aspect, the deterioration of the roundness of the yoke (4) is further suppressed, and the deterioration of the magnetic properties of the motor (1) is further suppressed.

[0087] The third aspect can be realized by combining the first or second aspect. In the third aspect, the yoke (4) is composed of a plurality of divided bodies (400) divided in the circumferential direction (10).

[0088] According to the third aspect, the effects of suppressing the deterioration of the roundness of the yoke (4) and the deterioration of the magnetic properties of the motor (1) can be more significantly achieved.

[0089] The fourth aspect can be realized by combining the first to third aspects. In the fourth aspect, a motor (1) includes a stator (2) and a rotor (3). The stator (2) has a stator core (21) of the first or second aspect and a winding (22) wound around the stator core (21).

[0090] According to the fourth aspect, the interference between the two inner surfaces (43, 43) and the two outer surfaces (53, 53) can be secured throughout the entire radial inward and outward direction, while suppressing deterioration of the magnetic characteristics of the motor (1) due to deformation of the radially inner ends of the recess (41) and the fitting portion (51). [Explanation of symbols]

[0091] 1 motor 10 Circumferential direction 2 stator 21 Stator core 22 windings 3 rotors 30 axis center 4 York 40 Inner surface 41 Recess 42 bottom 43 Inner surface 5 Teeth 50 Teeth body 51 Fitting part 52 Projecting end surface 53 External surface

Claims

1. a yoke that is annular in the circumferential direction and surrounds the axis of the rotor shaft; teeth formed separately from the yoke and protruding from an inner peripheral surface of the yoke toward the axis; The teeth are a teeth main body portion; a fitting portion protruding from the tooth main body portion toward an opposite side to the axis, The fitting portion is a protruding end surface facing away from the axis; two outer surfaces facing outward in the circumferential direction and continuous with each other on both sides of the protruding end surface in the circumferential direction, The length (W1) between the two outer surfaces in the circumferential direction at the end opposite to the axis is formed to be longer than the length (W2) between the two outer surfaces in the circumferential direction at the end on the axis center side, The yoke is a recess recessed from the inner circumferential surface toward the opposite side of the axis into which the fitting portion is fitted, The recessed portion is a bottom surface facing the axis; two inner surfaces facing inward in the circumferential direction, each of which is continuous with the bottom surface on both sides in the circumferential direction; a distance (L1) between the two inner surfaces in the circumferential direction at an end portion opposite to the axis is formed to be longer than a distance (L2) between the two inner surfaces in the circumferential direction at an end portion on the axis center side, An interference between the two outer surfaces and the two inner surfaces is set, and The angle (θ) formed by the inner surface with respect to the inner circumferential surface is 15 degrees or more and 45 degrees or less. Stator core.

2. The angle (θ) is 20 degrees or more and 40 degrees or less. The stator core according to claim 1 .

3. The yoke is configured by a plurality of divided bodies divided in the circumferential direction. The stator core according to claim 1 .

4. a stator; a rotor; The stator includes: The stator core according to claim 1 ; a winding wound around the stator core, Motor.

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