JP2020054211A - motor - Google Patents

Abstract

To provide a motor capable of restraining reduction of magnetic force of a magnet.SOLUTION: A motor includes a rotor having a medial axis J, and a stator facing the rotor in the radial direction. The rotor includes a rotor core 22a having multiple magnetic steel sheets laminated in the axial direction, a magnet placed on a face of the rotor core directing the radial direction, and a resin magnet holder 26 provided on the rotor core and holding the magnet. The rotor core has a first rotor core part 22 placed in a first region in the axial direction. The first rotor core part has a groove 28 recessed in the radial direction from a face of the first rotor core part directing the radial direction, and extends in the axial direction. The multiple magnetic steel sheets has a first magnetic steel sheet 41 having a recess constituting a part of the groove in the axial direction, in a face of the magnetic steel sheet directing the radial direction, and a second magnetic steel sheet 42 having a closing part overlapping and covering the recess when viewing from the axial direction. The second magnetic steel sheet is placed at the end of the first rotor core part in the axial direction.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a motor.

  The motor includes a rotor that rotates about a central axis, and a stator that radially faces the rotor. The rotor has a rotor core and a magnet. The rotor core is composed of a plurality of electromagnetic steel sheets stacked in the axial direction. The motor disclosed in Patent Document 1 is an inner rotor type motor in which a magnet is arranged on a radially outer surface of a rotor core. In Patent Literature 1, by providing a gap between the rotor core and the magnet, the flow of magnetic flux is improved.

Japanese Patent No. 55571480

  In order to fix the magnet to the rotor core, a magnet holder may be provided on the rotor core by resin molding. However, if a gap is provided as in Patent Literature 1, the molten resin flows into the gap and solidifies, and the magnet is arranged in a state of being floated in the radial direction from the rotor core by the resin, thereby reducing the magnetic force (demagnetization). To).

  In view of the above circumstances, an object of the present invention is to provide a motor that can stably contact a rotor core with a magnet and that can suppress a reduction in magnetic force of the magnet.

  One aspect of the motor of the present invention includes a rotor having a central axis, and a stator radially opposed to the rotor, wherein the rotor has a plurality of electromagnetic steel sheets stacked in an axial direction, and It has a magnet arranged on a surface facing the radial direction of the rotor core, and a resin magnet holder provided on the rotor core and holding the magnet, wherein the rotor core is arranged in a first region in the axial direction. A first rotor core portion, the first rotor core portion having a groove that is recessed in a radial direction from a surface facing the radial direction of the first rotor core portion and extends in an axial direction; A first electromagnetic steel sheet having a concave portion constituting a part of the groove portion in the axial direction on a surface facing the radial direction of the steel plate, and a second electromagnetic steel plate having a closing portion overlapping the concave portion and covering the concave portion when viewed from the axial direction. It includes a plate, a second magnetic steel sheet is disposed on the end portion in the axial direction of the first rotor core.

  ADVANTAGE OF THE INVENTION According to the motor of one aspect of the present invention, the rotor core and the magnet can be stably contacted, and the reduction of the magnetic force of the magnet can be suppressed.

FIG. 1 is a schematic sectional view of a motor according to one embodiment. FIG. 2 is a perspective view showing the rotor of one embodiment, and illustration of a magnet holder is omitted. FIG. 3 is a perspective view showing a rotor core of one embodiment. FIG. 4 is a partial cross-sectional view showing a part of the IV-IV cross section of FIG. FIG. 5 is a partial cross-sectional view showing a part of the VV cross section of FIG. FIG. 6 is a partial cross-sectional view showing a part of the VI-VI cross section of FIG. FIG. 7 is a perspective view showing a first rotor core portion and a magnet holder of one embodiment. FIG. 8 is a perspective view showing a first rotor core portion and a magnet holder of one embodiment. FIG. 9 is a cross-sectional perspective view showing a part of a mold for resin-molding the magnet holder. FIG. 10 is a perspective view illustrating a first rotor core portion and a magnet holder according to a modification of the embodiment.

  In the following description, the axial direction of the central axis J, that is, the direction parallel to the up-down direction is simply referred to as “axial direction”, the radial direction around the central axis J is simply referred to as “radial direction”, and the central axis J Is referred to simply as “circumferential direction”. In the present embodiment, the upper side (+ Z) corresponds to one side in the axial direction, and the lower side (-Z) corresponds to the other side in the axial direction. The side that advances counterclockwise in the circumferential direction when the motor 10 is viewed from top to bottom, that is, the side that advances in the direction of the arrow θ, is referred to as “one circumferential side”. As viewed from above, the side that advances clockwise in the circumferential direction, that is, the side that advances in the direction opposite to the direction of the arrow θ, is referred to as “the other side in the circumferential direction”. The terms “upper and lower”, “upper” and “lower” are simply names for describing the relative positional relationships of the respective components, and the actual positional relationships and the like are positional relationships and the like other than the positional relationships and the like indicated by these names. You may.

  Although not particularly shown, the motor 10 of the present embodiment is mounted on, for example, an electric power steering device. The electric power steering device is mounted on a steering mechanism of a vehicle wheel. An electric power steering device is a device that reduces steering force by a motor.

  As shown in FIG. 1, the motor 10 of the present embodiment includes a rotor 20 having a central axis J, a stator 30, a housing 11, and a plurality of bearings 15 and 16. The motor 10 of the present embodiment is an inner rotor type motor. The rotor 20 is arranged radially inside the stator 30 and rotates about the central axis J with respect to the stator 30. As shown in FIGS. 1 to 8, the rotor 20 includes a shaft 21, a rotor core 27, a magnet 25, and a magnet holder 26.

  The housing 11 has a cylindrical shape having a top and a bottom. The housing 11 has a peripheral wall 11a, a top wall 11b, a bottom wall 11c, and a bearing holder 11d. The peripheral wall part 11a is cylindrical. The top wall 11b has a plate shape and closes the upper opening of the peripheral wall 11a. The bottom wall 11c has a plate shape and closes the lower opening of the peripheral wall 11a. The bottom wall 11c holds the bearing 16. The bearing holder 11d is fixed to the inner peripheral surface of the peripheral wall 11a. The bearing holder 11d holds the bearing 15.

  The shaft 21 extends up and down around the central axis J. In the example of the present embodiment, the shaft 21 has a columnar shape extending in the axial direction. The shaft 21 is rotatably supported by a plurality of bearings 15 and 16 around a central axis J. The plurality of bearings 15 and 16 are arranged at intervals in the axial direction, and are supported by the housing 11. That is, the shaft 21 is supported by the housing 11 via the plurality of bearings 15 and 16.

  The shaft 21 is fixed to the rotor core 27 by press fitting or bonding. That is, the rotor core 27 is fixed to the shaft 21. Note that the shaft 21 may be fixed to the rotor core 27 via a resin member or the like. That is, the shaft 21 is directly or indirectly fixed to the rotor core 27. The shaft 21 is not limited to the columnar shape of the present embodiment, and may be, for example, a cylindrical shape.

  The rotor core 27 is cylindrical. The rotor core 27 has a shaft hole 27a. The shaft hole 27a is disposed at the center of the rotor core 27 when viewed from the axial direction. The shaft hole 27a is located on the central axis J and extends in the axial direction. The shaft hole 27a penetrates the rotor core 27 in the axial direction. The shaft hole 27a penetrates two first rotor core portions 22 and one second rotor core portion 23 described later in the axial direction. The shaft hole 27a has a circular hole shape. The shaft 21 is inserted into the shaft hole 27a. The outer shape of the rotor core 27 is substantially polygonal in a cross section perpendicular to the central axis J (hereinafter, sometimes simply referred to as a cross section). In the example of the present embodiment, the outer shape of the rotor core 27 is substantially octagonal in cross section. The rotor core 27 is a magnetic member. The rotor core 27 has a plurality of electromagnetic steel sheets stacked in the axial direction. Rotor core 27 is a steel sheet laminate formed by stacking a plurality of electromagnetic steel sheets in the axial direction.

  The rotor core 27 has a first rotor core 22 and a second rotor core 23. The first rotor core portion 22 is arranged in the first region S1 of the rotor core 27 in the axial direction. The first region S1 is at least a partial region along the axial direction of the rotor core 27. The first region S1 may be referred to as a first step or a first portion. The second rotor core portion 23 is disposed in a second region S2 of the rotor core 27 that is different from the first region S1 in the axial direction. The second region S2 is at least a partial region along the axial direction of the rotor core 27. The second region S2 may be referred to as a second step or a second portion. In the present embodiment, a total of three at least one first rotor core portion 22 and at least one second rotor core portion 23 are arranged alternately in the axial direction. That is, the rotor core 27 is a three-stage type rotor core.

  In the present embodiment, the rotor core 27 includes two first rotor cores 22 arranged at an interval in the axial direction and one second rotor core arranged between the two first rotor cores 22 in the axial direction. A part 23. The two first rotor core portions 22 are disposed at both axial ends of the rotor core 27. One second rotor core portion 23 is arranged at a central portion of the rotor core 27 in the axial direction. That is, the rotor 20 has two first regions S1 that are arranged apart from each other in the axial direction, and the two first regions S1 are located at both ends of the rotor 20 in the axial direction. The rotor 20 has one second region S2, and the one second region S2 is located between the two first regions S1 in the rotor 20 along the axial direction.

  In the example of the present embodiment, the axial length of the first rotor core portion 22 and the axial length of the second rotor core portion 23 are different from each other. Specifically, the axial length of the second rotor core portion 23 is slightly larger than the axial length of the first rotor core portion 22. However, the present invention is not limited to this, and the axial length of the first rotor core portion 22 and the axial length of the second rotor core portion 23 may be the same. The outer diameter of the first rotor core 22 and the outer diameter of the second rotor core 23 are the same.

  The first rotor core portion 22 has a first magnet mounting surface 22a, a through hole 22b, a holder mounting groove 22c, and a groove 28. The first magnet mounting surface 22a is arranged on a surface of the first rotor core portion 22 that faces in the radial direction. In the present embodiment, the first magnet mounting surface 22a is disposed on a surface of the first rotor core portion 22 that faces outward in the radial direction. The magnet 25 is arranged on the first magnet mounting surface 22a. The first magnet mounting surface 22a contacts the magnet 25 in the radial direction. A plurality of first magnet mounting surfaces 22a are arranged on the radially outer surface of the first rotor core portion 22 in a circumferential direction. In the example of the present embodiment, the first rotor core portion 22 has eight first magnet mounting surfaces 22a arranged in the circumferential direction on a radially outer surface of the first rotor core portion 22. Each first magnet mounting surface 22a is in contact with the radial inner surface 25b of the magnet 25, respectively.

  In the present embodiment, the first magnet mounting surface 22a has a planar shape extending in a direction perpendicular to the radial direction. That is, the first magnet mounting surface 22a is orthogonal to the radial direction. In a cross section perpendicular to the central axis J, the first magnet mounting surface 22a is a straight line extending in a direction perpendicular to the radial direction. The first magnet mounting surface 22a has a square shape when viewed from the outside in the radial direction. In the example of the present embodiment, the axial length of the first magnet mounting surface 22a is larger than the circumferential length. That is, the first magnet mounting surface 22 a extends in the axial direction on the radially outer surface of the first rotor core 22.

  The through-hole 22b penetrates the first rotor core portion 22 in the axial direction. A plurality of through holes 22b are arranged in the first rotor core portion 22 at intervals in the circumferential direction. In the example of the present embodiment, eight through holes 22b are arranged in the first rotor core portion 22 at equal intervals in the circumferential direction. The through-hole 22b is arranged at a portion of the first rotor core portion 22 other than the radially outer end. That is, the through-hole 22b is arranged at the radial inner end or radial center of the first rotor core 22 that does not affect the magnetic flux of the magnet 25. In a cross section perpendicular to the central axis J, the through hole 22b is circular. According to the present embodiment, the first rotor core portion 22 is lightened by the through-hole 22b, so that the weight of the first rotor core portion 22 and the material cost can be reduced.

  The holder mounting groove 22c is recessed radially inward from a radially outer surface of the first rotor core portion 22 and extends in the axial direction. The holder mounting groove 22c is disposed between a pair of circumferentially adjacent first magnet mounting surfaces 22a on the radially outer surface of the first rotor core portion 22, and opens radially outward. The holder mounting groove 22c is disposed on the radially outer surface of the first rotor core 22 over the entire length of the first rotor core 22 in the axial direction. The plurality of holder mounting grooves 22c are arranged on the radially outer surface of the first rotor core portion 22 at intervals in the circumferential direction. In the example of the present embodiment, eight holder mounting grooves 22c are arranged on the first rotor core portion 22 at equal intervals in the circumferential direction.

  The groove width of the holder mounting groove 22c decreases as it goes radially outward. That is, the width of the holder mounting groove 22c in the circumferential direction becomes smaller toward the outside in the radial direction. The opening located at the radially outer end of the holder mounting groove 22c opens between the circumferential ends of the pair of first magnet mounting surfaces 22a adjacent in the circumferential direction. In a cross section perpendicular to the central axis J, the holder mounting groove 22c has, for example, a wedge shape.

  The groove 28 is recessed in the radial direction from the surface of the first rotor core 22 facing in the radial direction, and extends in the axial direction. In the present embodiment, the groove 28 is recessed inward in the radial direction from a surface facing outward in the radial direction of the first rotor core portion 22 and opens outward in the radial direction. The groove 28 is arranged on the radially outer surface of the first rotor core 22 and extends in the axial direction at a portion other than the axial end of the radially outer surface. The plurality of grooves 28 are arranged on the radially outer surface of the first rotor core 22 at intervals in the circumferential direction.

  The groove 28 is disposed radially inward of the magnet 25 on the radially outer surface of the first rotor core 22. The groove 28 is disposed on the first magnet mounting surface 22a. A plurality of grooves 28 are provided on the first magnet mounting surface 22a at intervals in the circumferential direction. The grooves 28 are arranged at both ends in the circumferential direction of the first magnet mounting surface 22a. In the example of the present embodiment, the grooves 28 are arranged one by one at both ends in the circumferential direction of the first magnet mounting surface 22a.

  The groove portion 28 is arranged on the inner side in the circumferential direction from both ends 22e of the first magnet mounting surface 22a in the circumferential direction. In other words, the groove 28 is disposed closer to the center in the circumferential direction of the first magnet mounting surface 22a than to both ends 22e of the first magnet mounting surface 22a in the circumferential direction. Both ends 22 e of the first magnet mounting surface 22 a in the circumferential direction are in contact with both ends of the radial inner side surface 25 b of the magnet 25 in the circumferential direction. Both ends 22 e in the circumferential direction of the first magnet mounting surface 22 a contact both ends in the circumferential direction of the radial inner surface 25 b of the magnet 25 from the radial inside.

  The groove 28 forms a chamber that is a non-magnetic space on the first magnet mounting surface 22a. The groove 28 is a space filled with an atmosphere such as air, for example. The groove 28 may be referred to as a gap. In the example of the present embodiment, the groove 28 has a substantially square shape in a cross section perpendicular to the center axis J. The inner surface of the groove portion 28 has an inner surface portion facing in the radial direction and an inner surface portion facing in the circumferential direction. The circumferential length of the groove 28 is larger than the radial length of the groove 28. In the present embodiment, in the cross section, the radial length of the groove 28 is constant along the direction in which the first magnet mounting surface 22a extends. That is, in a cross-sectional view perpendicular to the central axis J, the first magnet mounting surface 22a linearly extends in a direction orthogonal to the radial direction, and extends along the extending direction of the first magnet mounting surface 22a. The radial dimension (depth) is constant. The shape and position of the groove 28 in a cross section perpendicular to the central axis J are constant along the axial direction.

  The groove 28 has a substantially square shape when viewed from the radial direction. The groove 28 has a rectangular shape when viewed from the radial direction. The axial length of the groove 28 is greater than the circumferential length of the groove 28. When viewed from the radial direction, the groove portion 28 is arranged so as to overlap with a portion other than the central portion in the circumferential direction on the radially outer surface 25a of the magnet 25. In the present embodiment, when viewed from the radial direction, the groove portion 28 is arranged so as to overlap with a portion other than the portion (that is, the top portion) located on the radially outer side of the radially outer surface 25 a of the magnet 25. The function (effect) of the groove 28 will be described later.

  The second rotor core portion 23 has a second magnet mounting surface 23a, a through hole 23b, and a holder mounting groove 23c. The second rotor core 23 does not have the groove 28. That is, the second rotor core portion 23 does not have the groove 28 on the surface facing the radial direction of the second rotor core portion 23. The groove 28 is not arranged on the second magnet mounting surface 23a.

  The second magnet mounting surface 23a is disposed on a surface of the second rotor core portion 23 that faces in the radial direction. In the present embodiment, the second magnet mounting surface 23a is disposed on a surface of the second rotor core portion 23 facing radially outward. The magnet 25 is arranged on the second magnet mounting surface 23a. The second magnet mounting surface 23a contacts the magnet 25 in the radial direction. A plurality of second magnet mounting surfaces 23a are arranged on the radially outer surface of the second rotor core portion 23 in a circumferential direction. In the example of the present embodiment, the second rotor core portion 23 has eight second magnet mounting surfaces 23a arranged in a circumferential direction on a radially outer surface of the second rotor core portion 23. Each second magnet mounting surface 23a is in contact with the radial inner surface 25b of the magnet 25, respectively.

  In the present embodiment, the second magnet mounting surface 23a has a planar shape extending in a direction perpendicular to the radial direction. That is, the second magnet mounting surface 23a is orthogonal to the radial direction. In a cross section perpendicular to the central axis J, the second magnet mounting surface 23a is a straight line extending in a direction perpendicular to the radial direction. The second magnet mounting surface 23a has a square shape when viewed from the outside in the radial direction. In the example of the present embodiment, the axial length of the second magnet mounting surface 23a is larger than the circumferential length. That is, the second magnet mounting surface 23 a extends in the axial direction on the radially outer surface of the second rotor core 23.

  The circumferential position of the first magnet mounting surface 22a of the first rotor core 22 and the circumferential position of the second magnet mounting surface 23a of the second rotor core 23 are different from each other. That is, the circumferential position of the first magnet mounting surface 22a is shifted from the circumferential position of the second magnet mounting surface 23a. In the example of the present embodiment, of the two first rotor core portions 22, one of the first rotor core portions 22 located on the upper side (+ Z side) with respect to the second magnet mounting surface 23 a of the second rotor core portion 23. The one magnet mounting surface 22a is displaced toward one circumferential side (+ θ side). Further, of the two first rotor core portions 22 with respect to the second magnet mounting surface 23a of the second rotor core portion 23, the first magnet mounting portion of the other first rotor core portion 22 located on the lower side (−Z side). The surface 22a is displaced toward the other circumferential side (−θ side).

  In the present embodiment, when viewed from the radial direction, the rotor core 27 has a 180 ° rotationally symmetrical shape about the second rotor core portion 23. That is, when viewed from the radial direction, the rotor core 27 has a 180 ° rotationally symmetrical shape around a predetermined center point located at the axial center of the second rotor core 23. According to the present embodiment, when the motor 10 is manufactured, it is possible to suppress the restriction on the assembly direction in the axial direction of the rotor core 27. An error in the mounting orientation of the rotor core 27 in the upper and lower directions can be eliminated, and the manufacture becomes easy.

  The through hole 23b penetrates through the second rotor core portion 23 in the axial direction. The plurality of through holes 23b are arranged in the second rotor core portion 23 at intervals in the circumferential direction. In the example of the present embodiment, eight through-holes 23b are arranged in the second rotor core portion 23 at equal intervals in the circumferential direction. The through-hole 23b is arranged in a portion of the second rotor core portion 23 other than the radially outer end. That is, the through-hole 23b is disposed at the radial inner end or radial center of the second rotor core 23 that does not affect the magnetic flux of the magnet 25. In a cross section perpendicular to the central axis J, the through-hole 23b has a circular shape. According to the present embodiment, the second rotor core portion 23 is lightened by the through-hole 23b, and the weight and material cost of the second rotor core portion 23 can be reduced.

  The holder mounting groove 23c is recessed radially inward from a radially outer surface of the second rotor core portion 23 and extends in the axial direction. The holder mounting groove 23c is disposed between a pair of second magnet mounting surfaces 23a adjacent in the circumferential direction on the radially outer surface of the second rotor core portion 23, and opens radially outward. The holder mounting groove 23c is arranged on the radially outer surface of the second rotor core portion 23 over the entire length of the second rotor core portion 23 in the axial direction. The plurality of holder mounting grooves 23c are arranged on the radially outer surface of the second rotor core portion 23 at intervals in the circumferential direction. In the example of the present embodiment, eight holder mounting grooves 23c are arranged in the second rotor core portion 23 at equal intervals in the circumferential direction.

  The groove width of the holder mounting groove 23c decreases as it goes radially outward. That is, the width of the holder mounting groove 23c in the circumferential direction decreases toward the outside in the radial direction. The opening located at the radially outer end of the holder mounting groove 23c opens between the circumferential ends of the pair of second magnet mounting surfaces 23a adjacent in the circumferential direction. In a cross section perpendicular to the central axis J, the holder mounting groove 23c has, for example, a wedge shape.

  The circumferential position of the holder mounting groove 22c of the first rotor core portion 22 and the circumferential position of the holder mounting groove 23c of the second rotor core portion 23 are different from each other. That is, the circumferential position of the holder mounting groove 22c and the circumferential position of the holder mounting groove 23c are shifted from each other. A magnet holder 26 is fixed to each of the holder mounting grooves 22c and 23c. According to the present embodiment, the wedge-shaped holder mounting grooves 22c and 23c are provided on the radially outer surface of the rotor core 27, so that the magnet holder 26 that is prevented from coming off in the radial direction with respect to the holder mounting grooves 22c and 23c. Can be provided, and the magnet holder 26 can hold the magnet 25 at least in the radial direction. The configuration and function of the magnet holder 26 will be described later.

  The first rotor core portion 22 has a plurality of electromagnetic steel sheets stacked in the axial direction. The first rotor core portion 22 is a steel sheet laminate formed by stacking a plurality of electromagnetic steel sheets in the axial direction. The second rotor core portion 23 has a plurality of electromagnetic steel sheets stacked in the axial direction. The second rotor core portion 23 is a steel sheet laminate formed by stacking a plurality of electromagnetic steel sheets in the axial direction. The plurality of electromagnetic steel sheets forming the first rotor core portion 22 and the second rotor core portion 23 will be described later.

  The magnet 25 is a permanent magnet. The magnet 25 is arranged on a surface of the rotor core 27 that faces in the radial direction. In the present embodiment, the magnet 25 is arranged on a surface of the rotor core 27 facing radially outward. A plurality of magnets 25 are arranged on the radially outer surface of the rotor core 27 in a circumferential direction. The plurality of magnets 25 are provided on the radially outer surface of the first rotor core portion 22 so as to be arranged in the circumferential direction. The plurality of magnets 25 are provided on the radially outer surface of the second rotor core portion 23 so as to be arranged in the circumferential direction. The plurality of magnets 25 are arranged at intervals in the circumferential direction. In the present embodiment, the plurality of magnets 25 are arranged at equal intervals in the circumferential direction. Holder mounting grooves 22c and 23c are arranged between a pair of magnets 25 adjacent in the circumferential direction. The magnets 25 are also arranged in the axial direction on the radially outer surface of the rotor core 27. The magnet 25 forms a part (part) of a radially outer surface of the rotor 20. That is, the radial outer surface 25 a of the magnet 25 is a part of the radial outer surface of the rotor 20. The rotor 20 of the present embodiment is a surface permanent magnet (SPM) in which a magnet 25 is disposed on a radially outer surface of the rotor 20.

  The magnet 25 is arranged on the radially outer surface of the first rotor core 22 over substantially the entire length of the first rotor core 22 in the axial direction. The magnets 25 are provided on the respective first magnet mounting surfaces 22a of the first rotor core 22. The magnet 25 contacts the first magnet mounting surface 22a from the outside in the radial direction. In the present embodiment, the circumferential length of the magnet 25 is substantially the same as the circumferential length of the first magnet mounting surface 22a.

  The magnet 25 is arranged on the radially outer surface of the second rotor core 23 over substantially the entire length of the second rotor core 23 in the axial direction. The magnets 25 are provided on the respective second magnet mounting surfaces 23a of the second rotor core 23. The magnet 25 contacts the second magnet mounting surface 23a from the outside in the radial direction. In the present embodiment, the circumferential length of the magnet 25 is substantially the same as the circumferential length of the second magnet mounting surface 23a. The magnet 25 disposed on the first magnet mounting surface 22a of the first rotor core 22 and the magnet 25 disposed on the second magnet mounting surface 23a of the second rotor core 23 are common members. In the present embodiment, the plurality of magnets 25 provided on the rotor core 27 have the same shape.

  The magnet 25 has a plate shape. The plate surface of the magnet 25 faces in the radial direction. The magnet 25 has a square shape when viewed from the radial direction. In the example of the present embodiment, the axial length of the magnet 25 is larger than the circumferential length of the magnet 25. That is, when viewed from the radial direction, the magnet 25 has a rectangular shape and extends in the axial direction. In a cross section perpendicular to the central axis J, the circumferential length of the magnet 25 is larger than the radial length of the magnet 25. The thickness of the magnet 25 in the radial direction increases from the both ends in the circumferential direction of the magnet 25 toward the center in the circumferential direction (inward in the circumferential direction).

  In a cross section perpendicular to the central axis J, the radial inner side surface 25b of the magnet 25 is linear. The radial inner surface 25b of the magnet 25 has a planar shape that extends in a direction perpendicular to the radial direction. The radial inner surface 25b of the magnet 25 has a square shape when viewed from the radial inside. The radial inner surface 25b of the magnet 25 contacts the first magnet mounting surface 22a. The radial inner surface 25b of the magnet 25 contacts the second magnet mounting surface 23a.

  In the cross section, the radial outer surface 25a of the magnet 25 has a convex curve shape. The radially outer surface 25a of the magnet 25 has a curved surface that protrudes radially outward in a cross section. 4 to 6 is an imaginary circle centered on the central axis J passing through at least a part of the radially outer surface 25a of the magnet 25 in the cross section. In the cross section, the radial outer surface 25a of the magnet 25 extends substantially along the virtual circle VC. In the example of the present embodiment, the radius of curvature of the radially outer surface 25a of the magnet 25 in the cross section is smaller than the radius of the virtual circle VC. In the cross section, the radially outer surface 25a of the magnet 25 has a circumferential center located on the virtual circle VC, and extends from the circumferential center to both circumferential sides (one circumferential side and the other circumferential side). As it moves, it is located away from the virtual circle VC inward in the radial direction. That is, the radially outer surface 25a of the magnet 25 is located radially inward from the center in the circumferential direction to both sides in the circumferential direction. In the present embodiment, on the radially outer surface 25a of the magnet 25, the portion located on the radially outermost side is the center in the circumferential direction, and the center in the circumferential direction is the vertex (top). The radially outer surface 25a of the magnet 25 has a rectangular shape when viewed from the radially outer side. The radial outer surface 25a of the magnet 25 radially opposes a later-described tooth 31b of the stator 30. That is, the radially outer surface of the rotor 20 radially opposes the teeth 31b.

  The function (effect) of the groove 28 will be described. According to the present embodiment, the magnetic flux of the magnet 25 is partially weakened in the circumferential direction by the groove 28. That is, when viewed from the radial direction, the magnetic flux in the portion of the magnet 25 that overlaps the groove 28 is weaker than when the magnet 25 does not overlap the groove 28. For this reason, the same effect as the case where the curvature of the radial outer surface 25a of the magnet 25 is changed by the groove 28 without changing the curvature of the radial outer surface 25a of the magnet 25 can be obtained. This operation effect is, for example, an effect of reducing the torque ripple of the entire motor 10 by partially generating the waveform of the torque ripple in the opposite phase. Then, vibration and noise generated by the motor 10 can be reduced. In other words, the groove 28 can simulate a curvature different from that of the radial outer surface 25 a of the magnet 25. That is, in the present embodiment, the groove portion 28 is provided at a position on the radially outer surface of the first rotor core portion 22 that overlaps with a portion where the curvature of the magnet 25 is desired to be changed when viewed from the radial direction. According to the present embodiment, the curvature of the radial outer surface 25a of the magnet 25 can be reduced by providing the groove 28. In other words, in the cross section, the radius of curvature of the radially outer surface 25a of the magnet 25 can be increased. Thereby, the shape of the magnet 25 can be approximated to a rectangular parallelepiped, and the material yield of the magnet 25 can be improved. Even if the specifications of the motor 10 are various, the necessity of changing the curvature of the magnet 25 according to the specifications of the motor 10 can be suppressed. That is, the necessity to prepare (a plurality of types of) magnets 25 having different shapes for each specification of the motor 10 is reduced. Then, the magnet 25 can be used as a common component. Therefore, the manufacturing cost of the motor 10 can be reduced.

  According to this embodiment, since the groove 28 faces the magnet 25 from the radial inside, the magnetic flux of the magnet 25 can be more stably controlled. Further, in the present embodiment, the grooves 28 are arranged at both ends in the circumferential direction of the first magnet mounting surface 22a. That is, when viewed from the radial direction, the groove portions 28 are arranged at positions on the radially outer surface 25a of the magnet 25 that overlap with both end portions in the circumferential direction. Specifically, the grooves 28 are arranged one by one in the first magnet mounting surface 22a at positions overlapping with both circumferential ends of the radial outer surface 25a of the magnet 25 when viewed from the radial direction. According to the present embodiment, the magnetic flux at the circumferential end of the magnet 25 can be weakened by the groove 28. Therefore, the same operation and effect can be obtained as in the case where the curvature is increased while the curvature of the circumferential end of the magnet 25 is kept small. The shape of the magnet 25 can be made closer to a rectangular parallelepiped, and the material yield of the magnet 25 is increased.

  In the present embodiment, the magnet 25 can be stably supported by both ends 22e of the first magnet mounting surface 22a in the circumferential direction while the above-described effects are obtained by the groove 28. That is, the magnet 25 is supported on the both ends 22e of the first magnet mounting surface 22a in the circumferential direction, so that the magnet 25 can be easily fixed, and it is possible to prevent rattling or tilting.

  The first rotor core portion 22 has a groove portion 28 on the surface facing the radial direction of the first rotor core portion 22, and the second rotor core portion 23 does not have the groove portion 28 on the surface facing the radial direction of the second rotor core portion 23. . The groove 28 is disposed only on the first magnet mounting surface 22 a of the first rotor core 22, and is not disposed on the second magnet mounting surface 23 a of the second rotor core 23. According to this embodiment, the magnet 25 provided on the radially outer surface of the first rotor core portion 22 and the magnet 25 provided on the radially outer surface of the second rotor core portion 23 share the same components as the first rotor core. In the magnet 25 of the part 22, a curvature different from the actual curvature can be simulated. As a result, the waveform of the torque ripple generated in the first region S1 and the waveform of the torque ripple generated in the second region S2 are generated in opposite phases to each other, and the fluctuation width of the waveform of the combined torque ripple (the combined torque ripple) (Difference between the maximum value and the minimum value of the waveform of FIG. 3) can be suppressed to a small value. Therefore, torque ripple can be reduced while suppressing the manufacturing cost of the motor 10.

  In the present embodiment, the circumferential position of the magnet 25 disposed on the first magnet mounting surface 22a of the first rotor core portion 22 and the circumferential direction of the magnet 25 disposed on the second magnet mounting surface 23a of the second rotor core portion 23 Positions are different from each other. That is, the circumferential position of the magnet 25 on the first magnet mounting surface 22a and the circumferential position of the magnet 25 on the second magnet mounting surface 23a are shifted from each other. That is, the magnets 25 of each stage of the first region S1 and the second region S2 are arranged so as to be shifted from each other in the circumferential direction, and the magnets 25 are step-skewed. Accordingly, the waveforms of the cogging torques generated in the first area S1 and the second area S2 are generated in opposite phases to each other, and the fluctuation width of the waveform of the combined cogging torque (the maximum value of the combined Difference from the minimum value) can be reduced. Therefore, cogging torque can be reduced. Then, vibration and noise generated by the motor 10 can be reduced.

  In a cross section perpendicular to the central axis J, the groove 28 has a circumferential length greater than a radial length. According to the present embodiment, it is possible to easily control the magnitude of the magnetic flux of the magnet 25 while securing the rigidity of the radially outer end of the first rotor core 22. According to the present embodiment, the above-described effects can be obtained by the groove 28 having a simple structure.

  The magnet holder 26 is provided on the rotor core 27 and holds the magnet 25. In the present embodiment, the magnet holder 26 is provided on a radially outer surface of the rotor core 27. The magnet holder 26 has a portion located between a pair of magnets 25 adjacent in the circumferential direction and extending in the axial direction. A plurality of magnet holders 26 are provided on the rotor core 27. The magnet holders 26 are provided on a radially outer surface of the first rotor core 22 and a radially outer surface of the second rotor core 23, respectively.

  The magnet holder 26 is made of resin. The magnet holder 26 of the first rotor core portion 22 is configured such that the first rotor core portion 22 is disposed in a mold 100 shown in FIG. 9 and molten resin flows from a plurality of gates 102 and is solidified in the mold 100. Formed by The magnet holder 26 of the second rotor core portion 23 is formed by disposing the second rotor core portion 23 in the mold 100, flowing molten resin from the plurality of gates 102, and solidifying the resin in the mold 100. .

  In FIG. 9, the central axis of the mold 100 is indicated by the symbol Jm. The first rotor core portion 22 and the second rotor core portion 23 are separately set in the mold 100 with their respective center axes J aligned with the center axis Jm of the mold 100. The first rotor core portion 22 and the second rotor core portion 23 are arranged in the mold 100 in a state where the magnet 25 is not mounted on the radially outer surface. The mold 100 has a plurality of magnet equivalent parts 101 arranged in the circumferential direction. The magnet equivalent part 101 has a shape similar to the magnet 25. Each magnet equivalent part 101 comes into contact with each first magnet mounting surface 22 a of the first rotor core part 22. The magnet equivalent portion 101 comes into contact with the first magnet mounting surface 22a from the outside in the radial direction. Each magnet equivalent part 101 comes into contact with each second magnet mounting surface 23 a of the second rotor core part 23. The magnet equivalent portion 101 comes into contact with the second magnet mounting surface 23a from the outside in the radial direction.

  The magnet holder 26 provided in the first rotor core portion 22 has an anchor portion 26a, a radial pressing portion 26b, and an axial pressing portion 26c. The magnet holder 26 provided on the second rotor core portion 23 has an anchor portion 26a and a radial pressing portion 26b. In the present embodiment, since the second rotor core portion 23 is disposed so as to be sandwiched between the two first rotor core portions 22 in the axial direction, the second rotor core portion 23 does not have the axial pressing portion 26c. However, the present invention is not limited to this. For example, in the case where the first rotor core portion 22 and the second rotor core portion 23 are each provided one by one, the second rotor core portion 23 has the axial pressing portion 26c. Is also good. The anchor part 26a, the radial pressing part 26b, and the axial pressing part 26c are parts of a single member.

  The anchor portion 26a is formed by filling and solidifying the molten resin between the holder mounting grooves 22c and 23c and the pair of magnet equivalent portions 101 adjacent in the circumferential direction. The anchor part 26a fits into the holder mounting grooves 22c and 23c. The anchor 26a extends in the axial direction. A plurality of anchor portions 26a are provided at intervals in the circumferential direction. The anchor portion 26a has a portion whose width in the circumferential direction increases toward the inside in the radial direction. The radial width of the inner end of the anchor portion 26a in the circumferential direction increases toward the inside in the radial direction. The portion of the anchor portion 26a other than the radially inner end portion has a circumferential width that increases in the radially outward direction.

  The radial pressing part 26b is connected to the anchor part 26a in the circumferential direction. The radial pressing portion 26b is disposed at a radially outer end of the magnet holder 26. The radial pressing portion 26b extends in the axial direction. The plurality of radial pressing portions 26b are provided at intervals in the circumferential direction. The radial pressing portions 26b protrude from the anchor portion 26a toward both circumferential sides (one circumferential side and the other circumferential side). The radial pressing portion 26b has a plate shape whose plate surface faces in the radial direction. The radial pressing portion 26b is disposed radially outward of the first magnet mounting surface 22a with a space between the first magnet mounting surface 22a and the first magnet mounting surface 22a. When viewed from the radial direction, the radial pressing portion 26b and the first magnet mounting surface 22a are arranged so as to overlap. The radial pressing portion 26b is disposed radially outside the second magnet mounting surface 23a with a space between the second magnet mounting surface 23a and the second magnet mounting surface 23a. When viewed from the radial direction, the radial pressing portion 26b and the second magnet mounting surface 23a are arranged so as to overlap.

  The radial pressing portion 26b contacts the magnet 25 from the radial direction. In the present embodiment, the radial pressing portion 26b contacts the magnet 25 from the radial outside. In other words, the plate surface facing radially inward of the radial pressing portion 26b contacts the radial outer surface 25a of the magnet 25. The plate surface facing radially inward of the radial pressing portion 26b contacts at least the circumferential end of the radial outer surface 25a of the magnet 25. The magnet 25 is disposed between the first magnet mounting surface 22a and the radial pressing portion 26b, for example, by being press-fitted in the axial direction. The magnet 25 is arranged between the second magnet mounting surface 23a and the radial pressing portion 26b, for example, by being press-fitted in the axial direction.

  According to the present embodiment, the magnet 25 can be pressed from the radial direction by the magnet holder 26, and the movement of the magnet 25 in the radial direction can be suppressed. As in the present embodiment, both ends 22e of the first magnet mounting surface 22a in the circumferential direction and both ends of the second magnet mounting surface 23a in the circumferential direction correspond to both ends of the radial inner side surface 25b of the magnet 25 in the circumferential direction. On the other hand, when the contact is made from the radial inner side, the holder mounting grooves 22c and 23c can be easily formed in a small space in the circumferential direction in a wedge shape, which is more preferable. In other words, it is easy to arrange the wedge-shaped holder mounting groove 22c and the anchor portion 26a in this gap while keeping the gap between the first magnet mounting faces 22a adjacent in the circumferential direction small. It is easy to arrange the wedge-shaped holder mounting groove 23c and the anchor portion 26a in this gap while keeping the gap between the second magnet mounting faces 23a adjacent in the circumferential direction small.

  The axial pressing portion 26c is connected to the anchor portion 26a and the radial pressing portion 26b in the axial direction. The axial pressing portion 26c has an annular shape centered on the central axis J. In the present embodiment, the axial pressing portion 26c has an annular plate shape. The axial pressing portion 26c is disposed only at one end of the axial both ends of the first rotor core portion 22. The axial pressing portion 26c contacts the magnet 25 from the axial direction. According to the present embodiment, the magnet 25 can be pressed from the axial direction by the magnet holder 26, and the movement of the magnet 25 in the axial direction can be suppressed.

  The plurality of electromagnetic steel sheets constituting the rotor core 27 will be described. The first rotor core portion 22 has a first electromagnetic steel plate 41 and a second electromagnetic steel plate 42. The second rotor core portion 23 has a third electromagnetic steel plate 43. That is, the plurality of magnetic steel sheets of the rotor core 27 include the first magnetic steel sheet 41, the second magnetic steel sheet 42, and the third magnetic steel sheet 43.

  The plurality of first electromagnetic steel sheets 41 are provided on the rotor core 27. A plurality of first electromagnetic steel sheets 41 are provided on the first rotor core portion 22. Each first electromagnetic steel sheet 41 forms a part of the first rotor core portion 22 in the axial direction. The plurality of first electromagnetic steel plates 41 are laminated in the axial direction at portions other than the axial end of the first rotor core portion 22. In the present embodiment, the plurality of first electromagnetic steel sheets 41 are arranged at a portion other than one end portion of both end portions of the first rotor core portion 22 in the axial direction. The first electromagnetic steel plate 41 has a substantially polygonal plate shape. The outer shape of the first electromagnetic steel sheet 41 is substantially polygonal in plan view when viewed from the axial direction. In the example of the present embodiment, the outer shape of the first electromagnetic steel sheet 41 is substantially octagonal in plan view.

  The first electromagnetic steel plate 41 has a shaft hole 41a, a first magnet mounting portion 41b, a through hole 41c, a holder mounting groove 41d, and a recess 41e. The shaft hole 41a is arranged at the center of the first electromagnetic steel sheet 41 when viewed from the axial direction. The shaft hole 41a is arranged coaxially with the central axis J in the first electromagnetic steel sheet 41. The shaft hole 41a penetrates the first electromagnetic steel plate 41 in the axial direction. The shaft hole 41a has a circular shape in plan view as viewed from the axial direction. The shaft hole 41a forms a part of the shaft hole 27a in the axial direction.

  The first magnet mounting portion 41b is arranged on a surface of the first electromagnetic steel plate 41 that faces in the radial direction. In the present embodiment, the first magnet mounting portion 41b is disposed on a surface of the first electromagnetic steel sheet 41 that faces radially outward. A plurality of first magnet mounting portions 41b are arranged on the radially outer surface of the first electromagnetic steel sheet 41 in a circumferential direction. In the example of the present embodiment, the first electromagnetic steel plate 41 has eight first magnet mounting portions 41b arranged in the circumferential direction on a radially outer surface of the first electromagnetic steel plate 41. Each of the first magnet mounting portions 41b is in contact with the radial inner surface 25b of the magnet 25, respectively. That is, the surface of the first electromagnetic steel plate 41 facing in the radial direction contacts the surface of the magnet 25 facing in the radial direction. In the present embodiment, the first magnet mounting portion 41b has a planar shape extending in a direction perpendicular to the radial direction. That is, the first magnet mounting portion 41b is orthogonal to the radial direction. In a plan view seen from the axial direction, the first magnet mounting portion 41b has a linear shape extending in a direction perpendicular to the radial direction. The first magnet mounting portion 41b forms a part of the first magnet mounting surface 22a in the axial direction.

  The through hole 41c penetrates the first electromagnetic steel plate 41 in the axial direction. The plurality of through-hole portions 41c are arranged on the first electromagnetic steel plate 41 at intervals in the circumferential direction. In the example of the present embodiment, eight through-hole portions 41c are arranged in the first electromagnetic steel plate 41 at equal intervals in the circumferential direction. The through-hole portion 41c is arranged at a portion other than the radially outer end portion of the first electromagnetic steel plate 41. In a plan view as viewed from the axial direction, the through-hole portion 41c has a circular shape. The through hole 41c forms a part of the through hole 22b in the axial direction.

  The holder mounting groove 41d has a concave shape recessed radially inward from a radially outer surface of the first electromagnetic steel plate 41. The holder mounting groove portion 41d is disposed between a pair of circumferentially adjacent first magnet mounting portions 41b on the radially outer surface of the first electromagnetic steel plate 41, and opens radially outward. The plurality of holder mounting grooves 41d are arranged on the radially outer surface of the first electromagnetic steel sheet 41 at intervals in the circumferential direction. In the example of the present embodiment, eight holder mounting grooves 41d are arranged on the radially outer surface of the first electromagnetic steel sheet 41 at equal intervals in the circumferential direction.

  The groove width of the holder mounting groove portion 41d becomes smaller as going outward in the radial direction. That is, the width of the holder mounting groove 41d in the circumferential direction becomes smaller as going outward in the radial direction. The opening located at the radially outer end of the holder mounting groove 41d opens between the circumferential ends of the pair of first magnet mounting portions 41b adjacent in the circumferential direction. The holder mounting groove 41d forms a part of the holder mounting groove 22c in the axial direction.

  The concave portion 41e is arranged on a surface of the electromagnetic steel plate that faces in the radial direction. The concave portion 41e has a concave shape that is recessed in the radial direction from the surface of the first electromagnetic steel plate 41 that faces in the radial direction. In the present embodiment, the concave portion 41e is recessed radially inward from the surface of the first electromagnetic steel plate 41 facing radially outward, and opens radially outward. The concave portion 41e is arranged on a radially outer surface of the first electromagnetic steel sheet 41. The plurality of recesses 41 e are arranged on the radially outer surface of the first electromagnetic steel sheet 41 at intervals in the circumferential direction.

  The concave portion 41 e is arranged on the radially outer surface of the first electromagnetic steel plate 41 and radially inward of the magnet 25. The concave portion 41e is arranged on the first magnet mounting portion 41b. The plurality of recesses 41e are provided in the first magnet mounting portion 41b at intervals in the circumferential direction. The concave portions 41e are arranged at both ends in the circumferential direction of the first magnet mounting portion 41b. In the example of the present embodiment, the concave portions 41e are arranged one by one at both ends in the circumferential direction of the first magnet mounting portion 41b.

  The concave portion 41e is arranged inward in the circumferential direction from both ends in the circumferential direction of the first magnet mounting portion 41b. That is, the concave portion 41e is disposed closer to the center in the circumferential direction of the first magnet mounting portion 41b than both ends in the circumferential direction of the first magnet mounting portion 41b. Both ends of the first magnet mounting portion 41b in the circumferential direction are in contact with both ends of the radial inner surface 25b of the magnet 25 in the circumferential direction. Both ends in the circumferential direction of the first magnet mounting portion 41b come into contact with both ends in the circumferential direction of the radial inner side surface 25b of the magnet 25 from the radial inside.

  In the example of the present embodiment, the concave portion 41e has a substantially square shape in a plan view as viewed from the axial direction. The inner surface of the concave portion 41e has an inner surface portion facing in the radial direction and an inner surface portion facing in the circumferential direction. The circumferential length of the recess 41e is larger than the radial length of the recess 41e. In the present embodiment, in plan view, the radial length of the concave portion 41e is constant along the direction in which the first magnet mounting portion 41b extends. That is, in plan view, the first magnet mounting portion 41b extends linearly in a direction orthogonal to the radial direction, and the radial dimension (depth) of the concave portion 41e along the extending direction of the first magnet mounting portion 41b. It is constant. The recess 41e forms a part of the groove 28 in the axial direction.

  At least one second electromagnetic steel sheet 42 is provided on the rotor core 27. In the present embodiment, a plurality of second electromagnetic steel sheets 42 are provided on the rotor core 27. At least one second electromagnetic steel sheet 42 is provided in the first rotor core portion 22. In the present embodiment, a plurality of second electromagnetic steel sheets 42 are provided in the first rotor core 22. The second electromagnetic steel plate 42 forms a part of the first rotor core portion 22 in the axial direction. The second electromagnetic steel plate 42 is disposed at an axial end of the first rotor core 22. In the present embodiment, the second electromagnetic steel sheet 42 is disposed at only one end of the axially opposite ends of the first rotor core 22. The second electromagnetic steel plate 42 has a substantially polygonal plate shape. The outer shape of the second electromagnetic steel plate 42 is substantially polygonal in plan view when viewed from the axial direction. In the example of the present embodiment, the outer shape of the second electromagnetic steel sheet 42 is substantially octagonal in plan view.

  The second electromagnetic steel plate 42 has a shaft hole 42a, a first magnet mounting portion 42b, a through hole 42c, a holder mounting groove 42d, and a closing portion 42e. The shaft hole 42a, the through hole 42c, and the holder mounting groove 42d of the second electromagnetic steel plate 42 have substantially the same configuration as the shaft hole 41a, the through hole 41c, and the holder mounting groove 41d of the first electromagnetic steel plate 41, respectively. Detailed description is omitted.

  The first magnet mounting portion 42b is disposed on a surface of the second electromagnetic steel plate 42 that faces in the radial direction. In the present embodiment, the first magnet mounting portion 42b is disposed on a surface of the second electromagnetic steel plate 42 that faces outward in the radial direction. The plurality of first magnet mounting portions 42b are arranged on the radially outer surface of the second electromagnetic steel plate 42 in a circumferential direction. In the example of the present embodiment, the second electromagnetic steel plate 42 has eight first magnet mounting portions 42b arranged in the circumferential direction on the radially outer surface of the second electromagnetic steel plate 42. Each of the first magnet mounting portions 42b is in contact with the radial inner surface 25b of the magnet 25, respectively. That is, the surface of the second electromagnetic steel plate 42 facing in the radial direction contacts the surface of the magnet 25 facing in the radial direction. According to the present embodiment, since both the first electromagnetic steel sheet 41 and the second electromagnetic steel sheet 42 are in radial contact with the magnet 25, the reduction of the magnetic force of the magnet 25 can be suppressed, and the occurrence of magnetic loss can be suppressed. Can be. In the present embodiment, the first magnet mounting portion 42b has a planar shape extending in a direction perpendicular to the radial direction. That is, the first magnet mounting portion 42b is orthogonal to the radial direction. In a plan view seen from the axial direction, the first magnet mounting portion 42b has a linear shape extending in a direction perpendicular to the radial direction. The first magnet mounting portion 42b forms a part of the first magnet mounting surface 22a in the axial direction.

  The configuration of the first magnet mounting portion 42b of the second electromagnetic steel plate 42 is different from that of the first magnet mounting portion 41b of the first electromagnetic steel plate 41 in that a closing portion 42e is arranged instead of the concave portion 41e. That is, the concave portion 41e is not arranged in the first magnet mounting portion 42b. The second electromagnetic steel sheet 42 does not have the concave portion 41e.

  The closing part 42e is arranged at a radial end of the electromagnetic steel sheet. In the present embodiment, the closing portion 42e is disposed at a radially outer end of the second electromagnetic steel plate 42. A plurality of closing portions 42e are arranged at a radially outer end of the second electromagnetic steel sheet 42 at intervals in the circumferential direction. The closing portion 42e is constituted by a part of the first magnet mounting portion 42b in the circumferential direction and a part of the radially outer end of the second electromagnetic steel sheet 42 located (adjacent) in the radial direction. . A plurality of closing portions 42e are provided at intervals in the circumferential direction in a range overlapping with one first magnet mounting portion 42b when viewed from the radial direction. The closing portions 42e are respectively arranged at positions overlapping with both ends in the circumferential direction of the first magnet mounting portion 42b when viewed from the radial direction. In the example of the present embodiment, the closing portions 42e are arranged one by one at positions overlapping with both ends in the circumferential direction of the first magnet mounting portion 42b when viewed from the radial direction.

  The closing portion 42e is disposed inward in the circumferential direction from both circumferential ends of the first magnet mounting portion 42b when viewed from the radial direction. That is, when viewed from the radial direction, the closing portion 42e is disposed closer to the center of the first magnet mounting portion 42b in the circumferential direction than both ends in the circumferential direction of the first magnet mounting portion 42b. The closing portion 42e overlaps with the concave portion 41e and covers the concave portion 41e when viewed from the axial direction. The closing portion 42e has substantially the same shape as the concave portion 41e when viewed from the axial direction. In the present embodiment, the closing portion 42e has a substantially square shape when viewed from the axial direction.

  According to the present embodiment, the concave portion 41e of the first electromagnetic steel plate 41 is closed by the closing portion 42e of the second electromagnetic steel plate 42 in the axial direction. That is, the groove 28 of the first rotor core 22 is closed at the axial end of the first rotor core 22 from the axial direction. For this reason, when manufacturing the motor 10, the molten resin flows into the groove 28 when the first rotor core 22 is arranged in the mold 100 and the magnet holder 26 is insert-molded in the first rotor core 22. This can be suppressed by the closing portion 42e. Specifically, at the time of resin molding of the magnet holder 26, instead of the magnet 25, the magnet-equivalent portion 101 of the mold 100 comes into contact with the surface facing the radial direction of the first rotor core portion 22, that is, the first magnet mounting surface 22 a. . A flow of the molten resin from the axial direction into the groove portion 28 between the magnet equivalent portion 101 and the first magnet mounting surface 22a can be suppressed by the closing portion 42e of the second electromagnetic steel plate 42. By suppressing the inflow of the resin into the groove 28, the first magnet mounting surface 22a and the magnet 25 are stably brought into close contact with each other at the time of assembling the rotor 20 in a post-process of resin molding. That is, the rotor core 27 and the magnet 25 are stably contacted.

  Specifically, unlike the present embodiment, when the closing portion 42e is not provided and the resin flows into the groove portion 28 during resin molding, the resin solidified in the groove portion 28 has a diameter larger than that of the first magnet mounting surface 22a. It protrudes outward in the direction. In this case, when the magnet 25 is attached to the first magnet attachment surface 22a in a later step, a radial gap is generated between the first magnet attachment surface 22a and the magnet 25. In other words, the magnet 25 may not be in close contact with the first magnet mounting surface 22a due to the resin, but may be arranged so as to partially float in the radial direction from the first magnet mounting surface 22a, and the magnetic force of the magnet 25 may be reduced. On the other hand, according to the present embodiment, the magnet 25 is prevented from floating in the radial direction from the first magnet mounting surface 22a, and the first magnet mounting surface 22a and the magnet 25 are stably contacted. Can be suppressed, and the occurrence of magnetic loss can be suppressed.

  Further, in the present embodiment, the second electromagnetic steel sheet 42 is disposed at only one end of both ends in the axial direction of the first rotor core 22. According to the present embodiment, the number of the second electromagnetic steel plates 42, which are heavier than the first electromagnetic steel plates 41, can be reduced, and the first rotor core portion 22 can be reduced in weight. In the present embodiment, it is preferable that a pin portion (not shown) projecting radially inward from the magnet equivalent portion 101 is provided on the magnet equivalent portion 101 of the mold 100. The pin portion is disposed in the groove portion 28 of the first rotor core portion 22 so as to be insertable in the axial direction. In this case, when the first rotor core portion 22 is installed in the mold 100, an error in the installation direction of the first rotor core portion 22 in the axial direction (an error in the vertical direction) can be suppressed by the pin portion.

  As shown in FIG. 7, in the present embodiment, a plurality of second electromagnetic steel sheets 42 are provided in an axial direction at the axial end of the first rotor core 22. In the illustrated example, two second electromagnetic steel plates 42 are provided so as to overlap each other in the axial direction at the end of the first rotor core portion 22. However, the present invention is not limited to this, and three or more second electromagnetic steel plates 42 may be provided at the axial end of the first rotor core portion 22 so as to overlap each other in the axial direction.

  According to the present embodiment, a large axial distance can be ensured between the axial end face 101 a of the magnet equivalent part 101 of the mold 100 and the axial end of the groove 28. That is, it is possible to secure a large length of the magnet-equivalent portion 101 to overhang the groove portion 28 in the axial direction. At the time of resin molding of the magnet holder 26, it is possible to further suppress the molten resin from entering the groove 28 from around the end face 101a of the magnet equivalent part 101. More specifically, a plurality of second electromagnetic steel plates 42 are stacked and provided on the axial end of the first rotor core portion 22, so that the end surface 101 a of the magnet-equivalent portion 101 faces in the axial direction and the axial direction of the groove 28. The axial distance between the end portions of the magnets, that is, the overhang amount of the magnet-equivalent portion 101 can be suppressed from becoming zero or a negative value even when, for example, a design tolerance or a manufacturing error occurs. The flow of the resin into the groove 28 is stably suppressed. Further, for example, even when the thickness (plate thickness) of the second electromagnetic steel sheet 42 is small, it is easy to suppress the resin from flowing into the groove 28.

  In the present embodiment, the second electromagnetic steel plate 42 is disposed between the first pressing member 26 c of the magnet holder 26 and the first electromagnetic steel plate 41 in the axial direction. That is, in the axial direction, the closing portion 42e is disposed between the axial pressing portion 26c and the concave portion 41e (the groove portion 28). Therefore, the flow of the molten resin into the groove 28 from the annular chamber 103 (see FIG. 9) in the mold 100 for forming the axial pressing portion 26c during the resin molding of the magnet holder 26 is prevented by the second method. The closing portion 42e of the electromagnetic steel plate 42 can stably suppress the occurrence.

  As shown in FIG. 3, in the present embodiment, second electromagnetic steel plates 42 are arranged at both axial ends of the rotor core 27. That is, the second electromagnetic steel sheets 42 are arranged only at both axial ends of the rotor core 27 in the entire rotor core 27. Specifically, each of the second electromagnetic steel plates 42 of the pair of first rotor core portions 22 is one end portion of the first rotor core portion 22 that is axially separated from the second rotor core portion 23 among the two axial end portions. Placed only in Therefore, it is possible to suppress the second electromagnetic steel sheet 42 of the first rotor core portion 22 from interfering with the magnetic characteristics of the magnet 25 disposed on the second rotor core portion 23.

  The plurality of third electromagnetic steel plates 43 are provided on the rotor core 27. A plurality of third electromagnetic steel plates 43 are provided on the second rotor core portion 23. Each third electromagnetic steel plate 43 forms a part of the second rotor core portion 23 in the axial direction. The plurality of third electromagnetic steel sheets 43 are laminated in the axial direction over the entire area of the second rotor core portion 23 in the axial direction. The third electromagnetic steel plate 43 has a substantially polygonal plate shape. The third electromagnetic steel plate 43 has a substantially polygonal outer shape in plan view when viewed from the axial direction. In the example of the present embodiment, the outer shape of the third electromagnetic steel plate 43 is substantially octagonal in plan view.

  The third electromagnetic steel plate 43 has a shaft hole 43a, a second magnet mounting portion 43b, a through hole 43c, and a holder mounting groove 43d. The shaft hole 43a, the through hole 43c, and the holder mounting groove 43d of the third electromagnetic steel plate 43 have substantially the same configuration as the shaft hole 42a, the through hole 42c, and the holder mounting groove 42d of the second electromagnetic steel plate 42, respectively. Detailed description is omitted.

  The second magnet mounting portion 43b is disposed on a surface of the third electromagnetic steel plate 43 that faces in the radial direction. In the present embodiment, the second magnet mounting portion 43b is arranged on a surface of the third electromagnetic steel plate 43 facing radially outward. A plurality of second magnet mounting portions 43b are arranged on the radially outer surface of the third electromagnetic steel plate 43 in a circumferential direction. In the example of the present embodiment, the third electromagnetic steel plate 43 has eight second magnet mounting portions 43b arranged on the radially outer surface of the third electromagnetic steel plate 43 in the circumferential direction. Each of the second magnet mounting portions 43b is in contact with the radial inner surface 25b of the magnet 25, respectively. That is, the surface of the third electromagnetic steel plate 43 facing in the radial direction contacts the surface of the magnet 25 facing in the radial direction. In the present embodiment, the second magnet mounting portion 43b has a planar shape extending in a direction perpendicular to the radial direction. That is, the second magnet mounting portion 43b is orthogonal to the radial direction. In a plan view seen from the axial direction, the second magnet mounting portion 43b has a linear shape extending in a direction perpendicular to the radial direction. The second magnet mounting portion 43b forms a part of the second magnet mounting surface 23a in the axial direction. Since the groove portion 28 is not arranged on the second magnet attachment surface 23a, the concave portion 41e is not arranged on the second magnet attachment portion 43b. The third electromagnetic steel sheet 43 may be a common member with the second electromagnetic steel sheet 42. In this case, the types of members constituting the rotor core 27 can be reduced.

  As shown in FIG. 1, the stator 30 faces the rotor 20 in the radial direction. In the present embodiment, the stator 30 is disposed radially outside the rotor 20 and faces the rotor 20 with a gap in the radial direction. The stator 30 has a stator core 31, an insulator 30Z, and a plurality of coils 30C.

  Stator core 31 has an annular shape centered on central axis J. Stator core 31 surrounds rotor 20 radially outside rotor 20. The stator core 31 is arranged radially outside the rotor 20 and faces the rotor 20 with a gap in the radial direction. The stator core 31 is, for example, a steel sheet laminate formed by stacking a plurality of electromagnetic steel sheets in the axial direction.

  The stator core 31 has a core back 31a and a plurality of teeth 31b. That is, the stator 30 has the core back 31a and the plurality of teeth 31b. The core back 31a is annular with the center axis as the center. The radially outer surface of the core back 31 a is directly or indirectly fixed to the inner peripheral surface of the peripheral wall 11 a of the housing 11. The teeth 31b extend radially inward from the radially inner side surface 31c of the core back 31a. The plurality of teeth 31b are arranged on the radially inner side surface 31c of the core back 31a at intervals in the circumferential direction. In the present embodiment, the teeth 31b are arranged at equal intervals in the circumferential direction. The teeth 31b face the magnet 25 in the radial direction. That is, the radial inner surface of the teeth 31b is spaced from the radial outer surface 25a of the magnet 25 of the first rotor core portion 22 and the radial outer surface 25a of the magnet 25 of the second rotor core portion 23 from the radial outside. opposite.

  The insulator 30Z is mounted on the stator core 31. The insulator 30Z has a portion that covers the teeth 31b. The material of the insulator 30Z is, for example, an insulating material such as a resin.

  The coil 30C is attached to the stator core 31. The plurality of coils 30C are mounted on the stator core 31 via the insulator 30Z. The plurality of coils 30C are configured by winding a conductive wire around each tooth 31b via the insulator 30Z.

  Note that the present invention is not limited to the above-described embodiment. For example, as described below, a configuration change or the like can be made without departing from the spirit of the present invention.

  In the above-described embodiment, a total of three first regions S1 and second regions S2 are arranged in the axial direction on the rotor core 27, and the first rotor core portions 22 and the second rotor core portions 23 are alternately arranged in the axial direction. Although an example in which a total of three are arranged has been described, the present invention is not limited to this. The first regions S1 and the second regions S2 may be arranged alternately in the axial direction on the rotor core 27 by the same number. In this case, the same number of the first rotor core portions 22 and the second rotor core portions 23 are arranged alternately in the axial direction. That is, the sum of the number of the first rotor core portions 22 and the number of the second rotor core portions 23 is an even number, and the first rotor core portions 22 and the second rotor core portions 23 are alternately arranged in the axial direction. As a result, the above-described effect of reducing the torque ripple can be more stably obtained. Note that the first rotor core portion 22 and the second rotor core portion 23 may be arranged one by one in the axial direction. In this case, the above-described effects can be obtained with a simpler structure.

  Further, only the first region S1 may be disposed on the rotor core 27, and the second region S2 may not be disposed. That is, in this case, the entire rotor core 27 is configured by one or a plurality of first rotor core portions 22.

  In the above-described embodiment, the step skew is applied to the plurality of magnets 25 that are adjacent in the axial direction. However, the step skew may not be applied particularly when reduction of the cogging torque is not required. That is, in this case, when viewed from the axial direction, the circumferential central portion of the magnet 25 of the first rotor core portion 22 and the circumferential central portion of the magnet 25 of the second rotor core portion 23 are arranged so as to overlap with each other. Further, when viewed from the axial direction, the circumferential central portions of the magnets 25 of the plurality of first rotor core portions 22 are arranged so as to overlap with each other.

  In the above-described embodiment, an example has been given in which the radius of curvature of the radial outer surface 25a of the magnet 25 is smaller than the radius of the virtual circle VC in the cross section perpendicular to the central axis J, but is not limited thereto. In a cross section perpendicular to the central axis J, the radial outer surface 25a of the magnet 25 may be located on the virtual circle VC over the entire circumferential area of the radial outer surface 25a. That is, in the cross section, the radius of curvature of the radial outer surface 25a of the magnet 25 and the radius of the virtual circle VC may be the same. In this case, the magnet 25 can be made closer to a rectangular parallelepiped, and the material yield of the magnet 25 is further improved.

  In the above-described embodiment, an example has been described in which the groove portions 28 are arranged one by one at both ends in the circumferential direction of one first magnet mounting surface 22a, but the present invention is not limited to this. Only one groove 28 may be arranged on one first magnet mounting surface 22a. Also, three or more grooves 28 may be provided on one first magnet mounting surface 22a at intervals in the circumferential direction. In any case, the closing portions 42e of the second electromagnetic steel plate 42 are provided in the same number as the number of the grooves 28 on one first magnet mounting surface 22a, and cover the concave portions 41e of the first electromagnetic steel plate 41 in the axial direction. That is, the groove 28 is closed from the axial direction.

  In the above-described embodiment, an example has been described in which the radial length (depth) of the groove portion 28 is constant along the direction in which the first magnet mounting surface 22a extends in a cross section perpendicular to the central axis J. However, it is not limited to this. In a cross section perpendicular to the central axis J, the radial length of the groove 28 may increase as it goes outward in the circumferential direction of the first magnet mounting surface 22a. Further, in the cross section, the radial length of the groove 28 may be smaller as going outward in the circumferential direction of the first magnet mounting surface 22a. In any case, the closing portion 42e of the second electromagnetic steel sheet 42 has substantially the same shape as the groove 28 when viewed in the axial direction, and closes the groove 28 in the axial direction.

  In the above-described embodiment, an example is given in which the shape and position of the cross section of the groove 28 are constant along the axial direction, but the present invention is not limited to this. The shape and position of the cross section of the groove 28 perpendicular to the central axis J may be different from each other in each part in the axial direction. In this case, the same operation and effect can be obtained as in the configuration in which the curvature of the radially outer surface 25a of the magnet 25 is changed at each portion in the axial direction. Therefore, it is easy to meet the requirements of various motor specifications. The closing portion 42e of the second electromagnetic steel plate 42 covers the concave portion 41e of the first electromagnetic steel plate 41 that comes into contact with the second electromagnetic steel plate 42 in the axial direction, thereby closing the groove 28 in the axial direction.

  In the above-described embodiment, an example has been described in which the second electromagnetic steel sheet 42 is disposed at only one end of the first rotor core 22 in the axial direction, but is not limited thereto. FIG. 10 shows a modification of the first rotor core portion 22 of the above-described embodiment. In this modification, a plurality of second electromagnetic steel sheets 42 are provided. The second electromagnetic steel plates 42 are disposed at both axial ends of the first rotor core 22. In the illustrated example, one second electromagnetic steel plate 42 is disposed at each axial end of the first rotor core 22. The plurality of first electromagnetic steel sheets 41 of the first rotor core portion 22 are disposed between the pair of second electromagnetic steel sheets 42 in the axial direction. According to this modification, the first rotor core portion 22 is less likely to be unbalanced in the axial direction. The imbalance is, for example, a magnetic force or weight imbalance. Further, when the first rotor core portion 22 is installed in the mold 100, the magnet-equivalent portion 101 of the mold 100 is prevented from coming into contact with the opening corner of the recess 41 e of the first electromagnetic steel sheet 41. Thus, the progress of partial wear of the magnet equivalent portion 101 is suppressed. In addition, when the first rotor core portion 22 is installed in the mold 100, it is possible to eliminate the restriction on the installation direction of the first rotor core portion 22 in the axial direction, thereby facilitating the manufacturing. Since the upper and lower installation directions of the first rotor core portion 22 do not have an error, there is no need to provide the magnet equivalent portion 101 with a pin portion or the like for suppressing the installation error of the first rotor core portion 22 in the axial direction. The structure of the mold 100 can be simplified.

  In the above-described embodiment, the inner rotor type motor 10 has been described as an example, but is not limited thereto. The present invention is also applicable to an outer rotor type motor. Although not particularly shown, in the outer rotor type motor, the rotor is disposed radially outside the stator and rotates about the center axis of the rotor with respect to the stator.

  In the above-described embodiment, an example in which the motor 10 is mounted on the electric power steering device has been described, but the embodiment is not limited thereto. The motor 10 can be used for various devices such as a pump, a brake, a clutch, a vacuum cleaner, a dryer, a sealing fan, a washing machine, and a refrigerator.

  In addition, the components (components) described in the above-described embodiments, modifications, and the like may be combined without departing from the spirit of the present invention. Changes are possible. The present invention is not limited by the above-described embodiments, but is limited only by the scope of the claims.

  10 motor, 20 rotor, 22 first rotor core, 22a first magnet mounting surface, 23 second rotor core portion, 23a second magnet mounting surface, 25 magnet, 25b radial inner surface (magnet) 26: magnet holder, 26b: radial pressing portion, 26c: axial pressing portion, 27: rotor core, 28: groove portion, 30: stator, 41: first electromagnetic steel sheet, 41b: first Magnet mounting part (the surface facing the radial direction of the first electromagnetic steel sheet), 41e ... concave part, 42 ... the second electromagnetic steel sheet, 42b ... first magnet mounting part (the surface facing the radial direction of the second electromagnetic steel sheet), 42e ... Part, J: central axis, S1: first area, S2: second area

Claims (12)

A rotor having a central axis;
A stator radially opposed to the rotor,
The rotor,
A rotor core having a plurality of electromagnetic steel sheets laminated in the axial direction,
A magnet arranged on a surface facing the radial direction of the rotor core,
A resin magnet holder provided on the rotor core and holding the magnet,
The rotor core has a first rotor core portion arranged in a first region in the axial direction,
The first rotor core portion has a groove that is recessed in the radial direction from a surface facing the radial direction of the first rotor core portion and extends in the axial direction,
The plurality of electromagnetic steel sheets,
A first electromagnetic steel sheet having a concave portion constituting a part of the groove in the axial direction on a surface facing the radial direction of the electromagnetic steel sheet;
A second electromagnetic steel sheet having a closing portion overlapping the concave portion and covering the concave portion, as viewed from the axial direction,
The motor, wherein the second electromagnetic steel sheet is disposed at an axial end of the first rotor core. The motor according to claim 1,
The first rotor core portion has a first magnet mounting surface on which the magnet is arranged, on a surface facing the radial direction of the first rotor core portion,
The plurality of grooves are provided on the first magnet mounting surface at intervals in the circumferential direction,
The motor, wherein the groove portions are arranged at both ends in a circumferential direction of the first magnet mounting surface. The motor according to claim 1 or 2,
A plurality of the second electromagnetic steel sheets are provided;
The motor, wherein the second magnetic steel sheets are respectively disposed at both axial ends of the first rotor core. The motor according to claim 1 or 2,
The motor, wherein the second magnetic steel sheet is disposed at only one end of both ends in the axial direction of the first rotor core. The motor according to claim 3 or 4, wherein
A motor, wherein a plurality of the second magnetic steel sheets are provided in an axial direction at an end of the first rotor core portion in an axial direction. The motor according to any one of claims 1 to 5,
The magnet holder,
A radial pressing portion that contacts the magnet from a radial direction,
An axial pressing portion that contacts the magnet from the axial direction,
The axial pressing portion is annular around the central axis,
The motor, wherein the second electromagnetic steel sheet is disposed in the axial direction between the axial pressing portion and the first electromagnetic steel sheet. The motor according to any one of claims 1 to 6, wherein
A motor, wherein a radially oriented surface of the first electromagnetic steel plate and a radially oriented surface of the second electromagnetic steel plate contact a radially oriented surface of the magnet. The motor according to any one of claims 1 to 7,
The rotor core has a second rotor core portion arranged in a second region different from the first region in the axial direction,
The motor, wherein the second rotor core portion does not have a groove on a surface facing the radial direction of the second rotor core portion. The motor according to claim 8, wherein
The first rotor core portion has a first magnet mounting surface on which the magnet is arranged, on a surface facing the radial direction of the first rotor core portion,
The second rotor core portion has a second magnet mounting surface on which the magnet is arranged, on a surface facing the radial direction of the second rotor core portion,
A motor, wherein a circumferential position of the first magnet mounting surface and a circumferential position of the second magnet mounting surface are shifted from each other. The motor according to claim 8 or 9, wherein
The rotor core,
Two first rotor core portions that are spaced apart from each other in the axial direction;
And one second rotor core portion disposed between the two first rotor core portions in the axial direction. The motor according to claim 10,
A motor in which the rotor core has a 180 ° rotationally symmetrical shape around the second rotor core portion when viewed from a radial direction. The motor according to claim 10 or 11, wherein
A motor, wherein the second electromagnetic steel sheet is disposed at both axial ends of the rotor core.

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