JP6459754B2 - motor - Google Patents

Description

  The present invention relates to a motor.

  For example, Patent Document 1 describes an axial air gap type electric motor.

JP 2008-125278 A

  In the axial gap type electric motor as described above, an attractive force is generated between the core and the magnet, and resistance to rotation of the rotor is generated. Such resistance is called cogging torque. When the cogging torque is large, the unevenness of the rotational torque of the electric motor becomes large, and there is a problem that vibration and noise occur in the motor.

  Further, the cogging torque is generated even when no current is supplied to the electric motor. Therefore, when the motor is used for the purpose of rotating the shaft even when no current is supplied to the motor, such as an electric power steering device and a bicycle with an electric assist, if the cogging torque is large, the operation burden on the user increases. There is a problem to do.

  In view of the above problems, an aspect of the present invention is to provide a motor having a structure that can reduce cogging torque.

One aspect of the motor of the present invention includes a shaft centering on a central axis extending in the vertical direction, an upper rotor attached to the shaft, a stator facing the upper rotor in the axial direction, a bearing that supports the shaft, Is provided. The upper rotor has an upper magnet facing the stator in the axial direction, and is located on the upper side of the stator. The upper magnet has a plurality of magnetic poles arranged along the circumferential direction. The stator has a plurality of cores arranged along the circumferential direction and a coil wound around the core. Each of the plurality of cores has an upper rotor facing surface that is a surface facing the upper rotor. A plurality of upper extending portions extending in the radial direction are provided on the upper rotor facing surface. The upper extending portion is a convex portion that is convex upward from the upper rotor facing surface, or a concave portion that is concave downward from the upper rotor facing surface. The number of upper extending portion which is provided for each upper rotor facing surface, Ri number der obtained by subtracting 1 least common multiple of the number of the number of the upper magnet pole of the core from the value obtained by dividing the number of cores in the axial direction When viewed, the center of the upper extending portion in the circumferential direction is a motor that overlaps a radial line that equally divides the stator into the least common multiple in the circumferential direction .

  According to one aspect of the present invention, a motor having a structure that can reduce cogging torque is provided.

FIG. 1 is a cross-sectional view showing the motor of the first embodiment. FIG. 2 is a plan view showing the upper rotor of the first embodiment. FIG. 3 is a cross-sectional view showing the stator of the first embodiment. FIG. 4 is a plan view showing the core of the first embodiment. FIG. 5 is a perspective view showing the core of the first embodiment. FIG. 6 is a perspective view showing the core of the second embodiment.

  Hereinafter, a motor according to an embodiment of the present invention will be described with reference to the drawings. The scope of the present invention is not limited to the following embodiments, and can be arbitrarily changed within the scope of the technical idea of the present invention. In the following drawings, the scale and number of each structure may be different from the scale and number of the actual structure in order to make each configuration easy to understand.

  In the drawings, an XYZ coordinate system is appropriately shown as a three-dimensional orthogonal coordinate system. In the XYZ coordinate system, the Z-axis direction is a direction parallel to the axial direction of the central axis J shown in FIG. The X-axis direction is a direction orthogonal to the Z-axis direction and is the left-right direction in FIG. The Y-axis direction is a direction orthogonal to both the X-axis direction and the Z-axis direction.

In the following description, the direction in which the central axis J extends (Z-axis direction) is the vertical direction. The positive side (+ Z side) in the Z-axis direction is called “upper side”, and the negative side (−Z side) in the Z-axis direction is called “lower side”. In addition, the up-down direction, the upper side, and the lower side are names used for explanation only, and do not limit the actual positional relationship and direction. Unless otherwise specified, a direction parallel to the central axis J (Z-axis direction) is simply referred to as an “axial direction”, and a radial direction around the central axis J is simply referred to as a “radial direction”. around the circumferential direction (theta _{Z-direction),} i.e., simply referred to as "circumferential direction" about the axis of the central axis J.

  In the present specification, the term “extending in the axial direction” includes not only strictly extending in the axial direction but also extending in a direction inclined with respect to the axial direction within a range of less than 45 °. Further, in this specification, the term “extend in the radial direction” means that it is strictly inclined in the range of less than 45 ° with respect to the radial direction in addition to the case of extending in the radial direction, that is, the direction perpendicular to the axial direction. This includes cases extending in the other direction.

<First Embodiment>
FIG. 1 is a cross-sectional view showing a motor 10 of the present embodiment. The motor 10 is an axial gap motor. As shown in FIG. 1, the motor 10 includes a housing 11, a shaft 20, two upper rotors 31 and a lower rotor 32, an upper bearing 51, a lower bearing 52, a stator 40, and a bus bar. A unit 70 and a connector 71 are provided.

  The housing 11 is a motor case of the motor 10. The housing 11 is made of metal or resin, for example. The housing 11 accommodates the shaft 20, the upper rotor 31, the lower rotor 32, the stator 40, the upper bearing 51, the lower bearing 52, and the bus bar unit 70. The housing 11 includes an intermediate housing 12, a lower housing 13, and an upper housing 14.

  The intermediate housing 12 has, for example, a cylindrical shape that is open at both ends in the axial direction. In the present embodiment, the lower rotor 32 is located inside the intermediate housing 12 in the radial direction.

  The lower housing 13 is attached to the lower side of the intermediate housing 12. The lower housing 13 is, for example, cylindrical. The lower housing 13 includes a bottom wall portion 13b, a cylindrical portion 13a, and a lower bearing holding portion 15.

  The bottom wall portion 13b has an annular shape that surrounds the shaft 20 in the circumferential direction. The cylinder portion 13a extends upward from the outer peripheral end of the bottom wall portion 13b. The upper end of the cylindrical portion 13 a is fitted into the lower opening 12 a of the intermediate housing 12. The lower bearing holding portion 15 is located on the radially inner side of the bottom wall portion 13b. The lower bearing holding portion 15 holds the lower bearing 52. The lower bearing holding portion 15 has an output shaft hole 15a that opens downward.

  The upper housing 14 is attached to the upper side of the intermediate housing 12 via a cover flange portion 45b of a cover 45 described later. The upper housing 14 is, for example, a covered cylindrical shape. In the present embodiment, the upper rotor 31, the stator 40, and the bus bar unit 70 are located on the radially inner side of the upper housing 14.

  In this specification, the motor case is a component that contacts a space outside the motor among components that house and protect driving components such as a rotor, a stator, and a shaft in the motor.

  The shaft 20 is centered on a central axis J extending in the vertical direction. The shaft 20 is rotatably supported around the central axis J by an upper bearing 51 and a lower bearing 52. That is, the upper bearing 51 and the lower bearing 52 are bearings that support the shaft 20. The lower end of the shaft 20 protrudes outside the housing 11 through the output shaft hole 15a.

  The upper rotor 31 and the lower rotor 32 are attached to the shaft 20 at a predetermined interval in the axial direction. The upper rotor 31 is located above the stator 40. The upper rotor 31 includes an upper rotor body 34 and a plurality of upper magnets 33.

  The upper rotor body 34 has, for example, a disk shape extending in the radial direction. In the present embodiment, the upper rotor body 34 is fixed to the upper end of the shaft 20. The upper magnet 33 is a magnet fixed to the lower surface of the upper rotor body 34. Although not shown, the plurality of upper magnets 33 are arranged along the circumferential direction. The magnetic poles of the upper magnet 33 are alternately provided with N and S poles along the circumferential direction. The upper magnet 33 faces the stator 40 in the axial direction.

  The lower rotor 32 is located below the stator 40. The lower rotor 32 has a lower rotor body 36 and a plurality of lower magnets 35. The lower rotor main body 36 has, for example, a disk shape extending in the radial direction. The lower rotor body 36 is fixed to the shaft 20. The lower magnet 35 is a magnet fixed to the upper surface of the lower rotor body 36. The plurality of lower magnets 35 are arranged along the circumferential direction. The magnetic poles of the lower magnet 35 are alternately provided with N and S poles along the circumferential direction. The lower magnet 35 faces the stator 40 in the axial direction. The upper magnet 33 and the lower magnet 35 have opposite polarities in the axial direction. Thereby, since a rotational torque is obtained by the upper rotor 31 and the lower rotor 32, the rotational torque of the motor 10 can be increased.

  The stator 40 is disposed between the two rotors, that is, between the upper rotor 31 and the lower rotor 32. The stator 40 includes a plurality of cores 41, a coil 42, an insulator 43, an upper bearing holder 44, a cover 45, and a mold resin portion 46. The stator 40 is molded by, for example, molding.

  The plurality of cores 41 are arranged along the circumferential direction. The plurality of cores 41 are located between the upper bearing holder 44 and the cover 45 in the radial direction. In the present embodiment, for example, twelve cores 41 are provided.

  The insulator 43 is attached to the core 41. The insulator 43 has a bobbin shape, for example. The insulator 43 is a member molded from a resin material, for example. The coil 42 is wound around the core 41 via the insulator 43. The coil 42 has a coil lead wire 42a. The coil 42 excites the core 41.

  The coil lead wire 42a is drawn from the coil 42 to the upper side. The coil lead wire 42 a extends upward from the core 41. The coil lead wire 42 a is electrically connected to the bus bar of the bus bar unit 70. The coil lead wire 42a may be a part of the winding constituting the coil 42, or may be a separate member from the winding constituting the coil 42.

  The upper bearing holder 44 is a bearing holder that holds the upper bearing 51. The upper bearing holder 44 is located on the radially inner side of the plurality of cores 41 and on the radially outer side of the shaft 20. The upper bearing holder 44 is cylindrical. In the present embodiment, the upper bearing holder 44 has a cylindrical shape concentric with the central axis J, for example. An upper bearing 51 is held on a holder inner peripheral surface 44 e that is an inner peripheral surface of the upper bearing holder 44.

  The cover 45 is disposed on the radially outer side of the plurality of cores 41. The cover 45 is cylindrical. The cover 45 includes a cover tubular portion 45a and a cover flange portion 45b. The cover tubular portion 45a is a tubular shape that extends in the axial direction and opens at both axial ends. In the present embodiment, the cover cylindrical portion 45a is, for example, a cylindrical shape concentric with the central axis J.

  The cover flange portion 45b extends radially outward from the lower end of the cover tubular portion 45a. The lower surface of the cover flange portion 45 b is in contact with the upper surface of the intermediate housing 12. The upper surface of the cover flange portion 45 b is in contact with the lower surface of the upper housing 14. The cover flange portion 45b is fixed to the housing 11 with a screw, for example. Thereby, the stator 40 is fixed to the housing 11. The end surface on the radially outer side of the cover flange portion 45 b is exposed to the outside of the motor 10.

  The mold resin portion 46 is located between the parts constituting the stator 40. The mold resin portion 46 is positioned, for example, between the coil 42 and the insulator 43, the radial direction between the upper bearing holder 44 and the cover 45.

  The bus bar unit 70 is located above the upper rotor 31. A coil lead wire 42 a is connected to the bus bar unit 70. The bus bar unit 70 holds a bus bar (not shown). The bus bar is electrically connected to the coil lead wire 42a. One end of the bus bar is exposed to the outside of the housing 11 via the connector 71.

  The connector 71 is provided in the upper housing 14, for example. Although not shown, the connector 71 has a hole that opens upward. One end of the bus bar in the bus bar unit 70 is exposed inside the hole. An external power supply (not shown) is connected to the connector 71. As a result, power is supplied from the external power source to the stator 40 via the bus bar and the coil lead wire 42a.

  Next, the upper rotor 31 and the lower rotor 32 will be described in detail. FIG. 2 is a plan view showing the upper rotor 31 of the present embodiment. As shown in FIG. 2, the upper magnet 33 includes a plurality of upper magnets 33N and a plurality of upper magnets 33S.

  The upper magnet 33N is a magnet magnetized to the N pole. The upper magnet 33S is a magnet magnetized to the S pole. That is, each upper magnet 33N and each upper magnet 33S has one magnetic pole. The plurality of upper magnets 33N and the plurality of upper magnets 33S are alternately arranged along the circumferential direction via the magnet gap Gm. Thereby, as the magnetic pole of the upper magnet 33, the N pole and the S pole are alternately provided along the circumferential direction. The magnet gap Gm is a gap between the upper magnet 33N and the upper magnet 33S adjacent in the circumferential direction, and is a boundary between the N pole and the S pole adjacent in the circumferential direction.

  In the present embodiment, for example, five upper magnets 33N and five upper magnets 33S are provided, respectively. That is, in this embodiment, the number of magnetic poles of the upper magnet 33 is 10, for example.

  As shown in FIG. 1, the lower magnet 35 includes a plurality of lower magnets 35N and a plurality of lower magnets 35S. The lower magnet 35N is a magnet magnetized to the N pole. The lower magnet 35S is a magnet magnetized to the S pole. Although not shown, the plurality of lower magnets 35N and the plurality of lower magnets 35S are alternately arranged along the circumferential direction. Thereby, as for the magnetic pole of the lower magnet 35, the N pole and the S pole are alternately provided along the circumferential direction. In the present embodiment, the number of magnetic poles of the lower magnet 35 is, for example, 10 like the upper magnet 33. That is, the number of magnetic poles of the upper magnet 33 and the number of magnetic poles of the lower magnet 35 are the same. As a result, the total number of magnetic poles of the magnet of the motor 10 is twice the number of magnetic poles of the upper magnet 33.

  The lower magnet 35N faces the upper magnet 33S in the axial direction. The lower magnet 35S faces the upper magnet 33N in the axial direction. Thus, the upper magnet 33 and the lower magnet 35 have different polarities facing each other in the axial direction.

  FIG. 3 is a cross-sectional view of the stator 40 as viewed in the radial direction. As shown in FIG. 3, in the present embodiment, the circumferential positions of the upper magnets 33N and 33S are slightly shifted from the circumferential positions of the lower magnets 35N and 35S. As a result, the magnetic field generated between the upper magnets 33N and 33S and the lower magnets 35N and 35S is inclined in the circumferential direction with respect to the central axis J. In other words, the skew between the upper magnet 33 and the lower magnet 35 is skewed in the circumferential direction with respect to the central axis J. The circumferential shift angle between the upper magnets 33N, 33S and the lower magnets 35N, 35S is, for example, 3 ° or more and 6 ° or less.

  As shown in FIG. 2, in the present embodiment, the outlines on both sides in the circumferential direction of the upper magnets 33N and 33S intersect the radial line passing through the central axis J in plan view. Although not shown, like the upper magnets 33N and 33S, the outlines on both sides in the circumferential direction of the lower magnets 35N and 35S intersect the radial line passing through the central axis J in plan view. Thereby, each of the upper magnets 33N and 33S and the lower magnets 35N and 35S is skewed in a circumferential direction with respect to the radial line.

  Next, the core 41 will be described in detail. 4 and 5 are diagrams showing the core 41 of the present embodiment. FIG. 4 is a plan view. FIG. 5 is a perspective view.

In the following description, theta _Z direction from the + Z side when viewed toward the -Z side counterclockwise as a positive direction, and negative clockwise direction when viewed toward the -Z side from the + Z side To do. Further, the direction (+ theta _Z direction) proceeds in the positive direction in the theta _Z direction is referred to as a forward rotational direction, the direction of travel in the negative direction of theta _Z direction (- [theta] _Z direction) is referred to as a reverse rotation direction.

  As shown in FIG. 4, the plurality of cores 41 are arranged at equal intervals in the circumferential direction via the slot opening Gc. The slot open Gc is a gap between the cores 41 adjacent in the circumferential direction. In the present embodiment, the slot open width L4, which is the dimension in the circumferential direction of the slot open Gc, is the same at any radial position. That is, in this embodiment, the circumferential distance between the cores 41 adjacent in the circumferential direction is the same at any radial position. Thereby, the timing at which the core 41 faces the upper magnet 33 and the timing at which the core 41 faces the lower magnet 35 can be varied depending on the radial position. That is, the core 41 can be skewed.

  The core 41 is made of a magnetic material. In the present embodiment, the core 41 is, for example, a single member. As shown in FIGS. 3 and 5, the core 41 includes a core columnar portion 41 a, an upper core flange portion 41 c, a lower core flange portion 41 b, an upper extension portion 47, and a lower extension portion 48. . As shown in FIG. 5, the core columnar portion 41a is a columnar shape extending in the axial direction. A coil 42 is wound around the core columnar portion 41a.

  The upper core flange portion 41c is connected to the upper end of the core columnar portion 41a. The upper core flange portion 41c has a plate shape extending in the radial direction. The upper core flange portion 41c extends on both sides in the radial direction from the core columnar portion 41a.

  As shown in FIG. 4, the shape of the upper core flange portion 41 c in a plan view (XY plane view) is a fan shape that expands from the radially inner side toward the radially outer side. That is, the shape of the upper rotor facing surface 41d, which is the upper surface of the upper core flange portion 41c, is a sector shape in which the upper rotor facing surface width L1, which is a circumferential dimension, increases from the radially inner side toward the radially outer side.

  The upper rotor facing surface 41 d is a surface facing the upper rotor 31 of the core 41. The upper rotor facing surface 41d is provided for each core 41. That is, the plurality of cores 41 each have an upper rotor facing surface 41 d that is a surface facing the upper rotor 31.

  In the present embodiment, the core flange portion side surfaces 41f and 41g, which are the side surfaces in the circumferential direction of the upper core flange portion 41c, intersect a radial line passing through the central axis J. The core flange portion side surfaces 41 f and 41 g are side surfaces in the circumferential direction of the core 41.

  The upper rotor facing surface 41d is provided with a plurality of upper extending portions 47 extending in the radial direction. The upper extending portion 47 is a convex portion that protrudes upward from the upper rotor facing surface 41d. The number of upper extending portions 47 provided for each upper rotor facing surface 41d is a number obtained by subtracting 1 from the value obtained by dividing the least common multiple of the number of cores 41 and the number of magnetic poles of upper magnet 33 by the number of cores 41. .

  For example, in the present embodiment, the number of cores 41 is 12, and the number of magnetic poles of the upper magnet 33 is 10. Therefore, the number of upper extending portions 47 provided for each upper rotor facing surface 41d is four. Thereby, in this embodiment, the upper side extension part 47 is, for example, the four upper sides of the first upper side extension part 47a, the second upper side extension part 47b, the third upper side extension part 47c, and the fourth upper side extension part 47d. Includes stretched part.

  The cogging torque of the motor 10 can be reduced by setting the number of the upper extending portions 47 provided for each upper rotor facing surface 41d as described above. Details will be described below.

  When the slot open Gc and the magnet gap Gm coincide with each other in the circumferential direction, the upper side magnets 33N and 33S excite the cores 41 on both sides in the circumferential direction of the slot open Gc with different polarities. Therefore, a magnetic circuit is generated between the upper magnets 33N and 33S and the cores 41 on both sides in the circumferential direction of the slot open Gc. This magnetic circuit generates an attractive force that maintains the state in which the slot open Gc and the magnet gap Gm coincide with each other in the circumferential direction.

For example, if the upper rotor 31 is moved in the forward rotational direction (+ theta _Z direction), this attraction, the upper rotor 31 receives a force in the reverse rotational direction (- [theta] _Z direction). The sum of the attractive forces generated by the magnetic circuit is the cogging torque generated in the upper rotor 31. This attractive force becomes the largest when the slot opening Gc and the magnet gap Gm coincide with each other in the circumferential direction. Therefore, a cogging torque peak occurs at the rotation angle of the upper rotor 31 where the slot open Gc and the magnet gap Gm coincide with each other in the circumferential direction.

  One magnet gap Gm passes through the slot open Gc by the number of cores 41 while the upper rotor 31 rotates once. In other words, the total number of times that the slot open Gc and the magnet gap Gm that occur during one rotation of the upper rotor 31 coincide with each other in the circumferential direction is equal to the number of cores 41, the number of magnet gaps Gm, that is, the number of magnetic poles of the upper magnet 33. It is a number multiplied by. On the other hand, the locations where the slot opening Gc and the magnet gap Gm coincide with each other in the circumferential direction are simultaneously generated by the greatest common divisor of the number of cores 41 and the number of magnetic poles of the upper magnet 33.

  Accordingly, the peak number of cogging torque generated during one rotation of the upper rotor 31 is obtained by multiplying the number of cores 41 by the number of magnetic poles of the upper magnet 33 and the number of cores 41 and the number of magnetic poles of the upper magnet 33. The number divided by the greatest common divisor. The number obtained by multiplying the number of cores 41 by the number of magnetic poles of the upper magnet 33 and dividing by the greatest common divisor of the number of cores 41 and the number of magnetic poles of the upper magnet 33 is the number of cores 41 and the upper magnet 33. The least common multiple with the number of magnetic poles.

As shown in FIG. 3, when the magnet gap Gm and the upper extending portion 47, for example, the second upper extending portion 47b in FIG. 3, coincide with the circumferential direction, the second upper extending portion 47b is magnetically In this direction, no torque is generated. When slightly shifted to the state from the magnet gap Gm is the forward rotational direction side (+ theta _Z side), and the second upper extending portion 47b, the upper core flange portion 41c which is positioned in the normal rotation direction of the second upper extending portion 47b The parts are excited with different polarities.

Thus, the upper magnet 33N, and 33S, and the second upper extending portion 47b, between the part of the upper core flange portion 41c which is positioned in the normal rotation direction (+ theta _Z side) of the second upper extending portion 47b, the magnetic A circuit is generated, and a repulsive force that moves the upper magnet 33 in the forward rotation direction is generated. That is, this repulsive force can apply a force opposite to the above-described attractive force to the upper rotor 31. Therefore, the peak of cogging torque can be reduced by providing the upper extending portion 47.

  As described above, the peak number of cogging torque is the least common multiple of the number of cores 41 and the number of magnetic poles of upper magnet 33. Therefore, in order to suitably reduce and cancel the cogging torque, the upper extending portion 47 is required by the least common multiple of the number of cores 41 and the number of magnetic poles of the upper magnet 33. Further, the magnet gap Gm and the slot open Gc are arranged at equal intervals in the circumferential direction. Therefore, when any one of the slot openings Gc and any one of the magnet gaps Gm coincide with each other in the circumferential direction, in order to make the other magnet gaps Gm coincide with the upper extending part 47 in the circumferential direction, The slot openings Gc are preferably arranged at equal intervals in the circumferential direction with the center in the circumferential direction as a base point.

  However, the upper extending portion 47 cannot be disposed at the position of the slot opening Gc. Therefore, in practice, the sum of the upper extending portions 47 arranged on the plurality of upper rotor facing surfaces 41d is reduced by the number of the slot open Gc from the least common multiple of the number of cores 41 and the number of magnetic poles of the upper magnet 33. A number is preferred.

  According to the present embodiment, the number of upper extending portions 47 provided for each upper rotor facing surface 41 d is obtained by dividing the least common multiple of the number of cores 41 and the number of magnetic poles of the upper magnet 33 by the number of cores 41. This is the number obtained by subtracting one. That is, the total number of the upper extending portions 47 provided on all the upper rotor facing surfaces 41 d is a number obtained by subtracting the number of cores 41 from the least common multiple of the number of cores 41 and the number of magnetic poles of the upper magnet 33. The number of cores 41 is the same as the number of slot opens Gc. Therefore, the total sum of the upper extending portions 47 arranged on the plurality of upper rotor facing surfaces 41d can be made by subtracting the number of slot openings Gc from the least common multiple of the number of cores 41 and the number of magnetic poles of the upper magnet 33.

  Thus, by arranging the upper extending portions 47 at equal intervals in the circumferential direction, when any one of the slot openings Gc and any one of the magnet gaps Gm coincide with each other in the circumferential direction, All other magnet gaps Gm that do not coincide with the direction can coincide with any one of the upper extending portions 47 in the circumferential direction. Therefore, when the slot opening Gc and the magnet gap Gm coincide with each other in the circumferential direction and the peak of the cogging torque is generated, a force opposite to the cogging torque is applied to the upper rotor 31 by the repulsive force by the plurality of upper extending portions 47. It is easy to reduce the peak size of cogging torque.

  As described above, according to the present embodiment, the motor 10 having a structure capable of reducing the cogging torque can be obtained.

  In the present specification, the upper extending portions 47 are arranged at equal intervals in the circumferential direction, and the number of the upper extending portions 47 is the least common multiple of the number of cores 41 and the number of magnetic poles of the upper magnet 33, In addition, when it is assumed that the upper extending portion 47 is also arranged at the position of the slot opening Gc, the upper extending portion 47 is placed at the position of the upper extending portion 47 when the upper extending portions 47 are arranged at equal intervals in the circumferential direction. Including placing. Actually, since the upper extending portion 47 cannot be disposed in the slot open Gc, the circumferential interval between the upper extending portions 47 adjacent in the circumferential direction across the slot open Gc is the circumferential distance on one upper rotor facing surface 41d. It is larger than the interval in the circumferential direction between the upper extending portions 47 adjacent to each other in the direction.

  Further, in the present specification, the fact that certain objects coincide with each other in the circumferential direction includes that the centers of certain objects in the circumferential direction overlap in the axial direction.

  In addition, according to the present embodiment, since the slot open width L4 is constant in the entire radial direction as described above, the core 41 is skewed. Thereby, the timing at which the slot open Gc and the magnet gap Gm coincide can be varied depending on the radial position. Accordingly, the timing at which cogging torque is generated between the upper rotor 31 and the core 41 and the timing at which cogging torque is generated between the lower rotor 32 and the core 41 can be made different depending on the radial position. As a result, the peak of cogging torque can be dispersed, and the magnitude of the peak of cogging torque generated in the motor 10 can be further reduced.

  Further, according to the present embodiment, as described above, the upper magnet 33 and the lower magnet 35 are each skewed in the circumferential direction with respect to the radial line. Therefore, the timing at which the slot opening Gc and the magnet gap Gm coincide can be made different depending on the radial position. Thereby, the magnitude of the peak of the cogging torque generated in the motor 10 can be further reduced.

  Further, according to the present embodiment, the skew is applied to the arrangement relationship between the upper magnet 33 and the lower magnet 35 as described above. Therefore, the timing at which the slot open Gc and the magnet gap Gm coincide can be made different between the upper rotor 31 and the lower rotor 32. Thereby, the timing at which cogging torque is generated between the upper rotor 31 and the core 41 and the timing at which cogging torque is generated between the lower rotor 32 and the core 41 can be differentiated. Therefore, the magnitude of the peak of cogging torque generated in the motor 10 can be further reduced.

  As shown in FIG. 4, in the present embodiment, the first upper extending portion 47a, the second upper extending portion 47b, the third upper extending portion 47c, and the fourth upper extending portion 47d are arranged in this order along the circumferential direction. In the present embodiment, the first upper extending portion 47a, the second upper extending portion 47b, the third upper extending portion 47c, and the fourth upper extending portion 47d are, for example, arranged at equal intervals in the circumferential direction on the upper rotor facing surface 41d. Is done. That is, the centers in the circumferential direction of the plurality of upper extending portions 47 provided for each upper rotor facing surface 41d are arranged at equal intervals along the circumferential direction.

  Therefore, when any one slot open Gc and any one magnet gap Gm coincide with each other in the circumferential direction, the other magnet gap Gm that does not coincide with the slot open Gc in any circumferential direction can be transferred to any of the upper extending portions 47. Easy to match the heel and circumferential direction. This makes it easier to reduce the peak of cogging torque.

  In the present embodiment, when viewed in the axial direction, the center in the circumferential direction of the upper extending portion 47 overlaps the equally-divided direction line C1. The equally-divided direction line C1 is a radial line that equally divides the stator 40 into the number of least common multiples of the number of cores 41 and the number of magnetic poles of the upper magnet 33 in the circumferential direction when viewed in the axial direction.

  As a result, when any one slot open Gc and any one magnet gap Gm coincide with each other in the circumferential direction, all the other magnet gaps Gm that do not coincide with the slot open Gc in the circumferential direction are moved upward. Any one of 47 can be made to coincide with the circumferential direction. Therefore, all peaks of cogging torque can be reduced. As a result, according to the present embodiment, the cogging torque can be further reduced.

  In the present embodiment, the upper extending portion 47 extends over the entire radial direction of the upper rotor facing surface 41d. Therefore, the cogging torque can be reduced by the upper extending portion 47 at any radial position on the upper rotor facing surface 41d.

  In the present specification, the upper extending portion extends over the entire radial direction of the rotor facing surface. When viewed in the axial direction, both ends in the radial direction of the upper extending portion are the outer line of the rotor facing surface. Including connecting. That is, in the present specification, the upper extending portion extends over the entire radial direction of the rotor facing surface. When viewed in the axial direction, the upper extending portion extends in the radial direction from the radially inner end of the rotor facing surface. Extending to the outer end, and extending the upper extending portion from the circumferential end of the rotor facing surface to the radially outer end.

  In the example of FIG. 4, when viewed in the axial direction, the first upper extending portion 47 a is from the core flange portion side surface 41 g to the core flange portion outer side surface 41 h that is the surface of the radially outer end of the upper core flange portion 41 c. Extend. The fourth upper extending portion 47d extends from the core flange portion side surface 41f to the core flange portion outer surface 41h. The core flange portion outer side surface 41 h is a surface at the radially outer end of the core 41. That is, when viewed in the axial direction, at least one of the upper extending portions 47 provided for each upper rotor facing surface 41 d extends from the side surface on one side in the circumferential direction of the core 41 to the radially outer end of the core 41. . The core flange portion side surfaces 41f and 41g are located at the end portion in the circumferential direction of the upper rotor facing surface 41d when viewed in the axial direction.

  When the upper extending portion 47 is provided along the equally-divided direction line C1 as in the present embodiment, if the slot opening width L4 is constant over the entire radial direction, the upper extending portion 47 includes the first extending portion 47. The upper extending portion 47 having a configuration such as the first upper extending portion 47a and the fourth upper extending portion 47d is likely to be included. In other words, the upper extension 47 includes an upper extension extending from the side surface on one side in the circumferential direction of the core 41 to the radially outer end of the core 41 so that the slot open width L4 is the same at any radial position. Cheap.

  The second upper extending portion 47b and the third upper extending portion 47c extend from the core flange portion inner side surface 41i, which is the radially inner end of the upper core flange portion 41c, to the core flange portion outer surface 41h. The core flange portion inner side surface 41 i is a surface at the radially inner end of the core 41.

  In the present embodiment, the stretched portion width L2 that is a dimension in the circumferential direction of the upper stretched portion 47 increases, for example, from the radially inner side toward the radially outer side.

  In an axial gap type motor such as the motor 10 of this embodiment, the distance in the circumferential direction in which the upper magnet 33 moves when the upper rotor 31 makes one rotation is such that the upper magnet 33 moves from the radially inner end of the upper magnet 33. The diameter increases toward the outer end in the radial direction. Therefore, for example, when the extended portion width L2 is the same in the entire radial direction, the ratio of the extended portion width L2 to the circumferential distance traveled by the upper magnet 33 during one rotation is the radial direction of the upper magnet 33. It decreases from the inner end toward the radially outer end of the upper magnet 33. Thereby, there exists a possibility that the reduction effect of a cogging torque may become small as the part near the radial direction outer end of the upper magnet 33. FIG.

  On the other hand, according to the present embodiment, since the extending portion width L2 increases from the radially inner side toward the radially outer side, the extending portion width L2 with respect to the circumferential distance traveled by the upper magnet 33 during one rotation. It is easy to make the ratio of the same over the entire radial direction. Thereby, according to this embodiment, it is easy to reduce cogging torque irrespective of a radial direction position.

  In the present embodiment, when viewed in the axial direction, the extended portion outlines VL1 and VL2 that are outlines on both sides in the circumferential direction of the upper extended portion 47 extend on a straight line passing through the central axis J. Therefore, the ratio of the extending portion width L2 to the circumferential distance in which the upper magnet 33 moves during one rotation can be made the same at any radial position. This makes it easier to reduce the cogging torque regardless of the radial position.

  An inter-extension-part width L3 that is a dimension in the circumferential direction between the adjacent upper extension parts 47 in the upper rotor facing surface 41d is larger than the extension part width L2. Therefore, on the upper rotor facing surface 41d, the area of the part where the upper extension part 47 is not provided can be made larger than the area of the part where the upper extension part 47 is provided. Thus, the upper extending portion 47 that is a convex portion can be provided with the upper rotor facing surface 41d as a reference, and thus the upper extending portion 47 can reduce the cogging torque.

  The shape of the cross section orthogonal to the radial direction of the upper extending portion 47 is not particularly limited, and may be, for example, a semicircular shape or a polygonal shape. In the example of FIG. 3, the shape of the cross section orthogonal to the radial direction of the upper extending portion 47 is, for example, a trapezoid.

  As shown in FIG. 5, the lower core flange portion 41b is connected to the lower end of the core columnar portion 41a. The lower core flange portion 41b has a plate shape extending in the radial direction. The lower core flange portion 41b extends on both sides in the radial direction with respect to the core columnar portion 41a.

  The planar view (XY plane view) shape of the lower core flange portion 41b is the same as the planar view shape of the upper core flange portion 41c. That is, the shape of the lower rotor facing surface 41e, which is the lower surface of the lower core flange portion 41b, is the same as the upper rotor facing surface 41d.

  The lower rotor facing surface 41 e is a surface facing the lower rotor 32 of the core 41. The lower rotor facing surface 41e is provided for each core 41. That is, the plurality of cores 41 each have a lower rotor facing surface 41 e that is a surface facing the lower rotor 32.

  As shown in FIG. 3, the lower rotor facing surface 41e is provided with a plurality of lower extending portions 48 extending in the radial direction. The lower extending portion 48 is a convex portion that protrudes downward from the lower rotor facing surface 41e.

  As described above, the peak number of cogging torque generated in the upper rotor 31 is determined by the number of cores 41 and the number of magnetic poles of the upper magnet 33. The same applies to the lower rotor 32. That is, the number of cogging torque peaks generated in the lower rotor 32 is determined by the number of cores 41 and the number of magnetic poles of the lower magnet 35. Therefore, in order to suitably reduce and cancel the cogging torque of the lower rotor 32, as in the case of the cogging torque in the upper rotor 31, the least common multiple of the number of cores 41 and the number of magnetic poles of the lower magnet 35 is set. The lower extending portion 48 is required by the amount.

  Also in the lower magnet 35, the magnet gaps Gm are arranged at equal intervals in the circumferential direction. Therefore, in the lower magnet 35, when any slot open Gc and any magnet gap Gm coincide with each other in the circumferential direction, the other magnet gap Gm coincides with the lower extending portion 48 in the circumferential direction. The lower extending portions 48 are preferably arranged at equal intervals in the circumferential direction with the center in the circumferential direction of one of the slot openings Gc as a base point.

  In the present embodiment, the number of magnetic poles of the lower magnet 35 is the same as the number of magnetic poles of the upper magnet 33. Accordingly, the total number of upper extending portions 47 and the total number of lower extending portions 48 are the same, and the circumferential arrangement of the upper extending portions 47 and the circumferential arrangement of the lower extending portions 48 are the same. Is preferred. That is, it is preferable that the arrangement of the extending portions is the same when the core 41 is viewed from above and when the core 41 is viewed from below. By arranging the extending portion in this way, both the cogging torque generated in the upper rotor 31 and the cogging torque generated in the lower rotor 32 can be suitably reduced.

  The preferable arrangement relationship between the upper extending portion 47 and the lower extending portion 48 described above is that the upper magnet 33 and the lower magnet 35 are skewed in the circumferential direction with respect to the central axis J as in the present embodiment. This is the same even when the skew is not applied. That is, even when the upper magnet 33 and the lower magnet 35 are skewed in the circumferential direction with respect to the central axis J as in the present embodiment, the total number of the upper extending portions 47 and the lower extending portions are reduced. The cogging torque generated in the upper rotor 31 and the lower rotor 32 are made the same with the total number of 48 and the circumferential arrangement of the upper extending portion 47 and the circumferential arrangement of the lower extending portion 48 are the same. Both of the cogging torques generated in the above can be suitably reduced.

  Specifically, in the present embodiment, the number of lower extending portions 48 provided for each lower rotor facing surface 41e is the least common multiple of the number of cores 41 and the number of magnetic poles of the lower magnet 35, which is the number of cores 41. It is the number obtained by subtracting 1 from the divided value.

  For example, in this embodiment, the number of cores 41 is 12, and the number of magnetic poles of the lower magnet 35 is 10. Therefore, the number of lower extending portions 48 provided for each lower rotor facing surface 41e is four. Accordingly, in the present embodiment, the lower extending portion 48 includes, for example, a first lower extending portion 48a, a second lower extending portion 48b, a third lower extending portion 48c, and a fourth lower extending portion 48d. And four lower extending portions.

  Therefore, according to the present embodiment, both the cogging torque generated in the upper rotor 31 and the cogging torque generated in the lower rotor 32 can be reduced. Thereby, the cogging torque of the entire motor 10 can be further reduced.

  The upper extending portion 47 and the lower extending portion 48 are provided at the same position in the circumferential direction. In other words, the upper extending portion 47 and the lower extending portion 48 overlap each other in the axial direction. Therefore, the upper extending portion 47 and the lower extending portion 48 reduce the cogging torque generated between the upper rotor 31 and the core 41 and the cogging torque generated between the lower rotor 32 and the core 41 at the same timing. it can. Thereby, the cogging torque of the entire motor 10 can be further reduced.

  Specifically, as shown in FIG. 3, the first upper extending portion 47a and the first lower extending portion 48a are provided at the same position in the circumferential direction. The second upper extending portion 47b and the second lower extending portion 48b are provided at the same position in the circumferential direction. The third upper extending portion 47c and the third lower extending portion 48c are provided at the same position in the circumferential direction. The fourth upper extending portion 47d and the fourth lower extending portion 48d are provided at the same position in the circumferential direction.

  Other configurations of the lower extending portion 48 are the same as the configurations of the upper extending portion 47. Other configurations of the lower core flange portion 41b are the same as the configurations of the upper core flange portion 41c.

  In addition, according to the present embodiment, two rotors are provided, and the upper rotor 31 and the core 41 and the lower rotor 32 and the core 41 face each other in the axial direction (Z-axis direction). The facing area of the rotor facing the can be increased. Thereby, the rotational torque of the motor 10 can be increased. On the other hand, when two rotors are provided, cogging torque is generated in each of the rotors, so that the total sum of the cogging torques generated in the entire motor 10 increases.

  In contrast, according to the present embodiment, as described above, both the cogging torque in the upper rotor 31 and the cogging torque in the lower rotor 32 are suitably reduced by the upper extending portion 47 and the lower extending portion 48. it can. Therefore, according to this embodiment, since the opposing area of the rotor facing the stator 40 in the entire motor 10 can be increased while suitably reducing the respective cogging torques, the rotational torque of the motor 10 can be further increased.

  In the present embodiment, the following configuration may be employed. In the following description, only the upper extending portion 47 may be described as a representative of the upper extending portion 47 and the lower extending portion 48.

  In the present embodiment, only one of the upper extending portion 47 and the lower extending portion 48 may be provided.

  In the present embodiment, the stretched portion width L2 may be the same at any position in the radial direction. In this case, the extended portion outlines VL1 and VL2 intersect with a straight line passing through the central axis J.

  In the present embodiment, the upper extending portion 47 may be provided in a part of the upper rotor facing surface 41d in the radial direction.

  In the present embodiment, the slot open width L4 may vary depending on the radial position. In the present embodiment, the slot open width L4 may increase, for example, from the radially inner side toward the radially outer side. In this case, for example, a configuration in which the core flange portion side surfaces 41f and 41g extend along the radial line can be employed.

  In the present embodiment, the upper extending portion 47 may include only one upper extending portion that extends from the side surface on one side in the circumferential direction of the core 41 to the radially outer end of the core 41, or may include three or more upper extending portions. In the present embodiment, the upper extending portion 47 may not include the upper extending portion extending from the side surface on one side in the circumferential direction of the core 41 to the radially outer end of the core 41.

  In the present embodiment, each part of the core 41 may be a separate member. That is, in the present embodiment, the upper extending portion 47 may be a separate member from the upper core flange portion 41c.

  In the present embodiment, the number of upper magnets 33 and the number of cores 41 are not particularly limited. In the present embodiment, the number of upper magnets 33: the number of cores 41 can be, for example, 2n: 3n, 4n: 3n, 8n: 9n, 10n: 12n. However, n is a natural number. In the example shown in FIGS. 1 to 5, the number of upper magnets 33: the number of cores 41 is 10:12.

  In the present embodiment, the magnet gap Gm may not be provided. That is, the upper magnet 33N and the upper magnet 33S may be arranged in contact with each other. The same applies to the lower magnet 35. In this case, the contact boundary between the upper magnet 33N and the upper magnet 33S corresponds to the magnet gap Gm in the description of the cogging torque. That is, when the boundary between the upper magnet 33N and the upper magnet 33S and the slot opening Gc coincide with each other in the circumferential direction, a peak of cogging torque occurs.

  In the present embodiment, the upper magnet 33 and the lower magnet 35 may each be a single member. In this case, the upper magnet 33 and the lower magnet 35 can be formed into, for example, an annular shape in which N poles and S poles are alternately arranged along the circumferential direction. In this case, the boundary between the N pole and the S pole corresponds to the magnet gap Gm in the description of the cogging torque.

  In the present embodiment, only one of the upper rotor 31 and the lower rotor 32 may be provided.

Second Embodiment
The second embodiment differs from the first embodiment in that the upper extending portion is a recess. In addition, about the structure similar to 1st Embodiment, description may be abbreviate | omitted by attaching | subjecting the same code | symbol suitably.

  FIG. 6 is a perspective view showing the core 141 of the present embodiment. As shown in FIG. 6, the core 141 includes a core columnar portion 41a, an upper core flange portion 141c, and a lower core flange portion 141b.

  The upper rotor facing surface 141d, which is the upper surface of the upper core flange portion 141c, is provided with a plurality of upper extending portions 147 extending in the radial direction. The upper rotor facing surface 141 d is a surface facing the upper rotor 31. The upper extending portion 147 is a recess that is recessed downward from the upper rotor facing surface 141d.

  In the present embodiment, the shape of the cross section orthogonal to the radial direction of the upper extending portion 147 is not particularly limited. In the example of FIG. 6, the shape of the cross section orthogonal to the radial direction of the upper extending portion 147 is, for example, a semicircular arc shape. The upper extending portion 147 includes a first upper extending portion 147a, a second upper extending portion 147b, a third upper extending portion 147c, and a fourth upper extending portion 147d. The first upper extending portion 147a, the second upper extending portion 147b, the third upper extending portion 147c, and the fourth upper extending portion 147d are arranged along the circumferential direction in this order.

  The first upper extending portion 147a is the same as the first upper extending portion 47a of the first embodiment except that it is a recess. The second upper extending portion 147b is the same as the second upper extending portion 47b of the first embodiment except that it is a recess. The third upper extending portion 147c is the same as the third upper extending portion 47c of the first embodiment except that it is a recess. The fourth upper extending portion 147d is the same as the fourth upper extending portion 47d of the first embodiment except that it is a recess.

  Although illustration is omitted, the lower rotor facing surface 141e, which is the lower surface of the lower core flange portion 141b, is provided with a plurality of lower extending portions extending in the radial direction. The lower rotor facing surface 141 e is a surface facing the lower rotor 32. The lower extending portion provided in the lower core flange portion 141b is a recess that is recessed upward from the lower rotor facing surface 141e. Other configurations of the lower extending portion are the same as those of the upper extending portion 147. The other configuration of the core 141 is the same as the configuration of the core 41 of the first embodiment.

  According to the present embodiment, as in the first embodiment, the cogging torque can be reduced by the upper extending portion 147 that is a recess and the lower extending portion (not shown).

  In the present embodiment, the following configuration may be employed.

  In the present embodiment, a configuration in which the upper extending portion 147 is a convex portion that protrudes upward from the upper rotor facing surface 141d, or a concave portion that is recessed downward from the upper rotor facing surface 141d can be employed. Further, in the present embodiment, a configuration in which the lower extending portion is a convex portion that protrudes downward from the lower rotor facing surface 141e or a concave portion that is recessed upward from the lower rotor facing surface 141e can be adopted. .

  That is, in the present embodiment, a part of the upper extending portion 147 may be a convex portion that protrudes upward from the upper rotor facing surface 141d. In the present embodiment, a part of the lower extending portion may be a convex portion that protrudes downward from the lower rotor facing surface 141e.

  In the present embodiment, all of the upper extending portion 147 is one of the convex portion and the concave portion, and all of the lower extending portion is the other one of the convex portion and the concave portion. Also good.

  In addition, each structure of 1st Embodiment described above and 2nd Embodiment can be suitably combined in the range which does not contradict each other.

  DESCRIPTION OF SYMBOLS 10 ... Motor, 20 ... Shaft, 31 ... Upper rotor, 32 ... Lower rotor, 33 ... Upper magnet, 35 ... Lower magnet, 40 ... Stator, 41, 141 ... Core, 41d, 141d ... Upper rotor facing surface, 41e , 141e ... lower rotor facing surface, 41f, 41g ... core flange side surface (side surface), 42 ... coil, 47, 47a, 47b, 47c, 47d, 147, 147a, 147b, 147c, 147d ... upper extension part, 48 , 48a, 48b, 48c, 48d ... lower extension part, 51 ... upper bearing (bearing), 52 ... lower bearing (bearing), C1 ... equally-divided direction line (radial direction line), J ... central axis, VL1 , VL2 ... Extension part outline (outline)

Claims (11)

A shaft centered on a central axis extending in the vertical direction;
An upper rotor attached to the shaft;
A stator facing the upper rotor in the axial direction;
A bearing that supports the shaft;
With
The upper rotor has an upper magnet facing the stator in the axial direction, and is located on the upper side of the stator,
The upper magnet has a plurality of magnetic poles arranged along the circumferential direction,
The stator has a plurality of cores arranged along a circumferential direction, and a coil wound around the core,
Each of the plurality of cores has an upper rotor facing surface that is a surface facing the upper rotor,
The upper rotor facing surface is provided with a plurality of upper extending portions extending in the radial direction,
The upper extending portion is a convex portion that is convex upward from the upper rotor facing surface, or a concave portion that is concave downward from the upper rotor facing surface,
The number of the upper extending portions provided for each upper rotor facing surface is a number obtained by subtracting 1 from the value obtained by dividing the least common multiple of the number of cores and the number of magnetic poles of the upper magnet by the number of cores. The
When viewed in the axial direction, the center of the upper extending portion in the circumferential direction overlaps a radial line that equally divides the stator into the least common multiple in the circumferential direction .   The motor according to claim 1, wherein a dimension in a circumferential direction of the upper extending portion increases from a radially inner side toward a radially outer side.   The motor according to claim 2, wherein when viewed in the axial direction, outlines on both sides in the circumferential direction of the upper extending portion extend on a straight line passing through the central axis.   The motor according to any one of claims 1 to 3, wherein the upper extending portion extends over the entire radial direction of the upper rotor facing surface.   5. The motor according to claim 1, wherein centers of a plurality of the upper extending portions provided for each upper rotor facing surface are arranged at equal intervals along the circumferential direction. The motor according to any one of claims 1 to 5 , wherein a circumferential distance between the cores adjacent in the circumferential direction is the same at any radial position. The shape of the upper rotor facing surface is a sector shape in which the circumferential dimension increases from the radially inner side to the radially outer side,
When viewed in the axial direction, at least one of the upper extending portions provided for each of the upper rotor facing surfaces extends from a side surface on one circumferential side of the core to a radially outer end of the core. Item 7. The motor according to Item 6 . The motor according to any one of claims 1 to 7 , wherein a dimension in a circumferential direction between adjacent upper extending parts on the upper rotor facing surface is larger than a dimension in a circumferential direction of the upper extending part. A lower rotor attached to the shaft;
The lower rotor has a lower magnet facing the stator in the axial direction, and is located on the lower side of the stator,
The lower magnet has a plurality of magnetic poles arranged along the circumferential direction,
The number of magnetic poles of the upper magnet and the number of magnetic poles of the lower magnet are the same,
Wherein the upper magnet and the lower magnet, opposite poles are axially opposed to each other, the motor according to any one of claims 1 to 8. The plurality of cores each have a lower rotor facing surface that is a surface facing the lower rotor,
The lower rotor facing surface is provided with a plurality of lower extending portions extending in the radial direction,
The lower extending portion is a convex portion that is convex downward from the lower rotor facing surface, or a concave portion that is concave upward from the lower rotor facing surface,
The number of the lower extension portions provided for each lower rotor facing surface is obtained by subtracting 1 from the value obtained by dividing the least common multiple of the number of cores and the number of magnetic poles of the lower magnet by the number of cores. The motor of claim 9 , which is a number. The motor according to claim 9 or 10 , wherein the upper extending portion and the lower extending portion are provided at the same position in the circumferential direction.

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