Motor

Abstract

To provide a motor having a structure capable of suppressing contact of a magnet with a stator.SOLUTION: A motor 100 includes rotors 20, 30 rotatable about a central axis, and a stator 50 located on one side in an axial direction of the rotors. The stator has a plurality of magnetic poles facing an end surface of each rotor on one side in the axial direction. Each rotor includes an annular rotor main body having at least one magnet, a rotor frame 21 having a plurality of arms extending in a radial direction, and a first cover 24 fixed to a rotor frame. At least a part or all of the magnets are magnetized in the axial direction. The plurality of arms is located on the other side of the rotor body in the axial direction. The first cover covers at least a portion of a surface of the magnet facing one side in the axial direction.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a motor. [Background technology]

[0002] Axial flux motors are known in which the stator is located on one axial side of the rotor (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Chinese Patent Application Publication No. 112491198 Summary of the Invention [Problem to be solved by the invention]

[0004] In an axial flux motor, the magnet of the rotor is subjected to a force in the direction that attracts it to the stator, which can cause the magnet to come off the rotor frame and move toward the stator, potentially causing the magnet to come into contact with the stator.

[0005] In view of the above circumstances, one object of the present invention is to provide a motor having a structure that can prevent the magnet from coming into contact with the stator. [Means for solving the problem]

[0006] One embodiment of the motor of the present invention comprises a rotor rotatable about a central axis and a stator located on one axial side of the rotor. The stator has multiple magnetic poles facing an end face on one axial side of the rotor. The rotor has an annular rotor body having at least one magnet, a rotor frame having multiple arms extending radially, and a first cover fixed to the rotor frame. The magnetization direction of at least some or all of the magnets is axial. The multiple arms are located on the other axial side of the rotor body. The first cover covers at least a portion of the surface of the magnet facing one axial side. [Effects of the Invention]

[0007] According to one aspect of the present invention, in a motor, it is possible to prevent a magnet from coming into contact with a stator. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a motor of a propulsion device according to a first embodiment. [Figure 2] FIG. 2 is a perspective view showing the motor of the propulsion device in the first embodiment, as viewed from an angle different from that of FIG. [Figure 3] FIG. 3 is a view of the motor of the propulsion device in the first embodiment as seen from the rear side. [Figure 4] FIG. 4 is a cross-sectional view showing the motor of the propulsion device in the first embodiment. [Figure 5] FIG. 5 is a perspective view showing the mounting member in the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing a part of the motor according to the first embodiment. [Figure 7] FIG. 7 is a perspective view showing the first rotor in the first embodiment. [Figure 8] FIG. 8 is an exploded perspective view showing the first rotor in the first embodiment. [Figure 9] FIG. 9 is a perspective view showing the first rotor frame and the second rotor frame in the first embodiment. [Figure 10] FIG. 10 is a perspective view showing a part of the first rotor frame in the first embodiment. [Figure 11] FIG. 11 is a cross-sectional view showing a part of the first rotor in the first embodiment. [Figure 12] FIG. 12 is a perspective view showing the rotor body in the first embodiment. [Figure 13] FIG. 13 is a perspective view showing a part of the annular member in the first embodiment. [Figure 14] FIG. 14 is a perspective view showing a part of the first rotor frame, a part of the annular member, and a part of the second covers in the first embodiment. [Figure 15] FIG. 15 is a perspective view showing a part of the first rotor in the first embodiment. [Figure 16] FIG. 16 is a cross-sectional view showing a part of the first rotor in the first embodiment, showing a portion different from that in FIG. [Figure 17] FIG. 17 is a view of the first cover of the first rotor in the first embodiment as seen from the front side. [Figure 18] FIG. 18 is a perspective view showing a part of the first cover in the first embodiment. [Figure 19] FIG. 19 is a perspective view showing a part of the first cover in the first embodiment, and is a view showing the part of the first cover as viewed from an angle different from that in FIG. [Figure 20] FIG. 20 is a perspective view showing a part of the first arm, a part of the first cover, and a part of the second cover in the first embodiment. [Figure 21] FIG. 21 is a cross-sectional view showing a part of the mounting member, a part of the first rotor, and a part of the stator in the first embodiment. [Figure 22] FIG. 22 is a perspective view showing the second cover in the first embodiment. [Figure 23] FIG. 23 is a perspective view showing the second rotor and the connecting cylinder in the first embodiment. [Figure 24]FIG. 24 is a cross-sectional view showing a part of the motor in the first embodiment, and is an enlarged view of a part of FIG. [Figure 25] FIG. 25 is an exploded perspective view showing the first rolling bearing, the second rolling bearing, the first spacer, the second spacer, and the bearing support member in the first embodiment. [Figure 26] FIG. 26 is a perspective view showing a portion including a preload member in the motor according to the first embodiment. [Figure 27] FIG. 27 is a perspective view showing the stator in the first embodiment. [Figure 28] FIG. 28 is a perspective view showing the stator in the first embodiment, and is a perspective view showing the stator from an angle different from that in FIG. [Figure 29] FIG. 29 is a cross-sectional view showing a part of the stator in the first embodiment, and is a view showing a cross section perpendicular to the axial direction. [Figure 30] FIG. 30 is a cross-sectional view showing a part of the stator in the first embodiment, and is a view showing a cross section perpendicular to the circumferential direction. [Figure 31] FIG. 31 is a perspective view showing the inner housing and the outer housing in the first embodiment. [Figure 32] FIG. 32 is a cross-sectional perspective view showing a part of the inner housing in the first embodiment. [Figure 33] FIG. 33 is a perspective view showing a part of the inner housing and a part of the outer housing in the first embodiment. [Figure 34] FIG. 34 is a perspective view showing a part of the outer housing, a part of the stator cover, and a part of the stator support portion in the first embodiment. [Figure 35] FIG. 35 is a perspective view showing the stator cover in the first embodiment. [Figure 36] FIG. 36 is a cross-sectional perspective view showing a part of the stator in the first embodiment. [Figure 37] FIG. 37 is a perspective view showing a part of the stator in the first embodiment. [Figure 38]FIG. 38 is a perspective view showing the bus bar in the first embodiment. [Figure 39] FIG. 39 is a cross-sectional perspective view showing a part of the motor of the propulsion device in the second embodiment. [Figure 40] FIG. 40 is a perspective view showing a part of the motor of the propulsion device in the second embodiment. [Figure 41] FIG. 41 is a cross-sectional view showing a part of the stator in the third embodiment. [Figure 42] FIG. 42 is a cross-sectional view showing a part of the stator in the fourth embodiment. [Figure 43] FIG. 43 is a cross-sectional view showing a motor of a propulsion device according to the fifth embodiment. [Figure 44] FIG. 44 is a perspective view showing a motor of a propulsion device according to the sixth embodiment. [Figure 45] FIG. 45 is a cross-sectional view showing a motor of a propulsion device according to the sixth embodiment. [Figure 46] FIG. 46 is a cross-sectional view showing a part of the motor of the propulsion device according to the sixth embodiment. [Figure 47] FIG. 47 is a cross-sectional view showing the motor of the propulsion device in the sixth embodiment, and is a view showing a cross section perpendicular to the axial direction. [Figure 48] FIG. 48 is a cross-sectional perspective view showing the motor of the propulsion device according to the seventh embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] In each drawing, a central axis J of the motor in each of the following embodiments is shown as appropriate. The central axis J is a virtual axis. In the following description, the direction in which the central axis J extends, i.e., the axial direction of the central axis J, will be simply referred to as the "axial direction," the radial direction centered on the central axis J will be simply referred to as the "radial direction," and the circumferential direction centered on the central axis J will be simply referred to as the "circumferential direction." In each drawing, a Z axis parallel to the axial direction is shown. In the following description, the side of the axial direction toward which the arrow of the Z axis points (+Z side) will be referred to as the "front side," and the side of the axial direction opposite to the side toward which the arrow of the Z axis points (-Z side) will be referred to as the "rear side." Note that the terms "front side" and "rear side" are simply names used to describe the relative positions of the various components, and the actual relative positions may be other than those indicated by these names.

[0010] First Embodiment The motor 100 shown in Figures 1 to 3 is a motor provided in a propulsion device 1000. The propulsion device 1000 is mounted on, for example, an unmanned aerial vehicle. The propulsion device 1000 generates propulsive force for moving the unmanned aerial vehicle. As shown in Figure 4, the propulsion device 1000 includes a motor 100 and a propeller 1100. The propeller 1100 is rotated about a central axis J by the motor 100. The propeller 1100 is attached to a second rotor 30 of the motor 100, which will be described later. The propeller 1100 has a base 1110 fixed to the second rotor 30 and a plurality of blades 1120 connected to the base 1110. The plurality of blades 1120 extend radially and are spaced apart circumferentially.

[0011] Motor 100 is an axial flux motor. In this embodiment, motor 100 is a double-rotor axial flux motor whose rotors include a first rotor 20 and a second rotor 30. Motor 100 includes mounting member 10, first rotor 20, second rotor 30, connecting cylinder 40, stator 50, busbar assembly 60, first rolling bearing 71a, second rolling bearing 71b, first spacer 72a, second spacer 72b, bearing support member 73, preload member 74, and conductive member 75.

[0012] The mounting member 10 is attached to a device on which the motor 100 is mounted. The mounting member 10 supports the first rotor 20, the second rotor 30, and the stator 50. The mounting member 10 is electrically conductive. The mounting member 10 is made of a non-magnetic material. In this specification, "a certain object is made of a non-magnetic material" includes a certain object being made of a paramagnetic material and a certain object being made of a diamagnetic material. In this embodiment, the mounting member 10 is made of metal. The metal constituting the mounting member 10 is, for example, aluminum.

[0013] As shown in FIG. 5, the mounting member 10 has a support shaft 11 and a plurality of stator support parts 12. In other words, the motor 100 includes the support shaft 11 and a plurality of stator support parts 12. The support shaft 11 is cylindrical and extends axially along the central axis J. More specifically, the support shaft 11 is cylindrical and has a center on the central axis J. As shown in FIG. 4, the support shaft 11 opens to the front side (+Z side) and the rear side (-Z side). The rear end of the support shaft 11 is located more rearward than the first rotor 20. The support shaft 11 rotatably supports the first rotor 20 and the second rotor 30 via a first rolling bearing 71a and a second rolling bearing 71b.

[0014] As shown in FIG. 5, a step portion 15 having a second step surface 15a facing the front side (+Z side) is provided on the rear side (-Z side) of the outer circumferential surface of the support shaft 11. The second step surface 15a is annular and surrounds the central axis J. More specifically, the second step surface 15a is annular and has a center that coincides with the central axis J in a plan view along the axial direction. The second step surface 15a is a surface perpendicular to the axial direction. The outer diameter of the portion of the support shaft 11 located on the rear side of the second step surface 15a is larger than the outer diameter of the portion of the support shaft 11 located on the front side of the second step surface 15a.

[0015] A step portion 17 having a third step surface 17a facing the front side is provided on a front-side (+Z side) portion of the inner circumferential surface of the support shaft 11. The third step surface 17a is annular and surrounds the central axis J. More specifically, the third step surface 17a is annular and has a center that coincides with the central axis J in a plan view along the axial direction. The third step surface 17a is a surface perpendicular to the axial direction. The inner diameter of the portion of the support shaft 11 located closer to the front than the third step surface 17a is larger than the inner diameter of the portion of the support shaft 11 located closer to the rear side (-Z side) than the third step surface 17a.

[0016] The support shaft 11 has a first thread portion 16 on its outer circumferential surface. As shown in Fig. 6, the first thread portion 16 is provided on the outer circumferential surface of a portion of the support shaft 11 that is located closer to the front side (+Z side) than the inner ring 71f of the second rolling bearing 71b. In this embodiment, the first thread portion 16 is provided on the outer circumferential surface of the support shaft 11 at the end on the front side.

[0017] As shown in FIG. 4 , a conductive member 75 is disposed inside the support shaft 11. The conductive member 75 is annular and surrounds the central axis J. More specifically, the conductive member 75 is annular and has a center coincident with the central axis J in a plan view along the axial direction. The conductive member 75 is conductive. The conductive member 75 is made of a non-magnetic material. The conductive member 75 is made of, for example, a metal. The metal constituting the conductive member 75 is, for example, aluminum. The conductive member 75 is fitted into the front end of the support shaft 11. The outer circumferential surface of the conductive member 75 contacts the inner circumferential surface of the support shaft 11. The conductive member 75 is fixed inside the support shaft 11 by, for example, press fitting. Note that the conductive member 75 may also be fixed inside the support shaft 11 by other methods, such as shrink fitting. A radially outer edge portion of the rear-side (-Z side) surface of the conductive member 75 contacts the third step surface 17a. This positions the conductive member 75 relative to the support shaft 11 in the axial direction.

[0018] As shown in FIG. 5, the multiple stator support portions 12 are arranged at intervals in the circumferential direction. In this embodiment, six stator support portions 12 are provided. Each of the multiple stator support portions 12 has a first extension portion 13 and a support column portion 14. The first extension portion 13 extends in the radial direction. As shown in FIG. 6, the radially inner end of the first extension portion 13 is connected to a portion of the support shaft 11 that is located closer to the rear (-Z side) than the first rotor 20. The radially outer end of the first extension portion 13 is located radially outward than the first rotor 20. As shown in FIG. 5, the first extension portion 13 has a first plate-shaped portion 13a, a second plate-shaped portion 13b, and a tip portion 13c.

[0019] The first plate-shaped portion 13a extends in the radial direction. The first plate-shaped portion 13a is a plate whose plate surface faces the circumferential direction. The radially inner end of the first plate-shaped portion 13a is connected to the support shaft 11. The rear side (-Z side) end of the first plate-shaped portion 13a is positioned toward the front side (+Z side) as it moves radially outward.

[0020] The second plate-shaped portion 13b extends in the radial direction. The second plate-shaped portion 13b is a plate-shaped portion whose plate surface faces the axial direction. The second plate-shaped portion 13b is connected to the front-side (+Z side) end of the first plate-shaped portion 13a. The radially inner end of the second plate-shaped portion 13b is connected to the support shaft 11. The second plate-shaped portion 13b protrudes from the front-side end of the first plate-shaped portion 13a on both sides in the circumferential direction. The circumferential dimension of the second plate-shaped portion 13b decreases radially outward.

[0021] The tip portion 13c is connected to the radially outer end of the first plate-shaped portion 13a and the radially outer end of the second plate-shaped portion 13b. The tip portion 13c is substantially rectangular parallelepiped-shaped. The tip portion 13c has a screw hole 13d that is recessed radially inward from the radially outer surface of the tip portion 13c. A bolt (not shown) that secures the mounting member 10 to the equipment on which the motor 100 is mounted is fastened into the screw hole 13d. The motor 100 is secured to the equipment on which the motor 100 is mounted by fastening each tip portion 13c of the multiple stator support portions 12 to the equipment with a bolt (not shown).

[0022] As shown in FIG. 6, the support column portion 14 protrudes toward the front side (+Z side) from a portion of the first extension portion 13 that is located radially outward from the first rotor 20. In this embodiment, the support column portion 14 protrudes toward the front side from the radially outer end of the first extension portion 13, i.e., the tip portion 13c. The support column portion 14 is located radially outward from the first rotor 20. As shown in FIG. 5, in this embodiment, the support column portion 14 has a substantially square column shape extending in the axial direction. The support column portion 14 has a support column main body portion 14a and a wall portion 14b. The support column main body portion 14a has a substantially square column shape that protrudes toward the front side from the tip portion 13c. The support column main body portion 14a has a screw hole 14c that is recessed from the front side surface of the support column main body portion 14a toward the rear side (-Z side). 6, the front surface of the support pillar main body 14a contacts the rear surface (-Z side) of a housing fixed portion 52f (described later) of the stator 50. This brings the support pillar 14 into contact with the rear surface of the housing fixed portion 52f. The multiple stator supports 12 support the stator 50 from the rear side by the support pillars 14.

[0023] 5, the wall portion 14b protrudes toward the front side from the radially outer edge of the front (+Z side) surface of the support column main body 14a. The wall portion 14b is located radially outward of the screw holes 14c. The wall portion 14b extends from one circumferential edge of the support column main body 14a to the other circumferential edge.

[0024] The first rotor 20 and the second rotor 30 are rotatable around the central axis J. As shown in FIG. 4 , the second rotor 30 is located away from the first rotor 20 on the front side (+Z side). The first rotor 20 is located on the rear side (-Z side) of the stator 50. The second rotor 30 is located on the front side of the stator 50. That is, in this embodiment, the rotors are arranged on both axial sides of the stator 50. In the first rotor 20 of this embodiment, the side on which the stator 50 is located relative to the first rotor 20, i.e., the front side (+Z side), is the "one axial side," and the side on which the first rotor 20 is located relative to the stator 50, i.e., the rear side (-Z side), is the "other axial side." In the second rotor 30 of this embodiment, the side on which the stator 50 is located relative to the second rotor 30, i.e., the rear side, is the "one axial side," and the side on which the second rotor 30 is located relative to the stator 50, i.e., the front side, is the "other axial side."

[0025] As shown in FIG. 7, the first rotor 20 has an annular shape surrounding the central axis J. More specifically, the first rotor 20 has a substantially circular annular shape whose center coincides with the central axis J in a plan view along the axial direction. As shown in FIG. 4, the first rotor 20 is located closer to the front (+Z side) than the first extension portions 13 of the multiple stator support portions 12. The first rotor 20 is located radially outward from the support shaft 11 and surrounds the support shaft 11.

[0026] As shown in FIG. 8, the first rotor 20 has a first rotor frame 21, a rotor main body 23, a first cover 24, and a plurality of second covers 25. The first rotor frame 21 is electrically conductive. The first rotor frame 21 is made of a non-magnetic material. In this embodiment, the first rotor frame 21 is made of metal. The metal constituting the first rotor frame 21 is, for example, aluminum. The first rotor frame 21 has a first rotor annular portion 21a, a plurality of first protruding walls 21b, and a plurality of first arms 22.

[0027] The first rotor annular portion 21a has an annular shape surrounding the central axis J. More specifically, the first rotor annular portion 21a has a substantially circular annular shape whose center coincides with the central axis J in a plan view along the axial direction. The first rotor annular portion 21a has a plurality of holes 21c that penetrate the first rotor annular portion 21a in the axial direction. The plurality of holes 21c are arranged at intervals in the circumferential direction.

[0028] The multiple first protruding walls 21b are protruding walls that protrude from the radial outer edge of the first rotor annular portion 21a toward the front side (+Z side). The multiple first protruding walls 21b are arranged at intervals in the circumferential direction. The multiple first protruding walls 21b extend in the circumferential direction. The radially inner surface 21d of the multiple first protruding walls 21b has an arc shape that extends in the circumferential direction in a plan view along the axial direction. As shown in FIG. 9, the multiple first protruding walls 21b are located radially outside the connecting tube 40 and are arranged to surround the connecting tube 40. In this embodiment, six first protruding walls 21b are provided.

[0029] The multiple first arms 22 extend in the radial direction. Each of the multiple first arms 22 extends radially outward from the outer circumferential surface of the first rotor annular portion 21a. Each of the multiple first arms 22 is arranged at intervals from one another along the circumferential direction. In this embodiment, the multiple first arms 22 are arranged at equal intervals around the circumference. As shown in FIG. 4, the multiple first arms 22 are located on the rear side (-Z side) of the rotor body 23. The multiple first arms 22 are located closer to the front side (+Z side) than the multiple first extension portions 13. As shown in FIG. 10, each of the multiple first arms 22 has an arm main body portion 22f extending in the radial direction, a retaining wall 22g protruding toward the front side from a radially outer end of the arm main body portion 22f, and a first protruding portion 22h protruding radially inward from a front end of the retaining wall 22g.

[0030] The arm main body portion 22f extends radially outward from the outer peripheral surface of the first rotor annular portion 21a. The arm main body portion 22f has a mounting surface 22p. That is, each of the multiple first arms 22 has a mounting surface 22p. The mounting surface 22p is a part of the front-side (+Z side) surface of the arm main body portion 22f. The mounting surface 22p faces the front side. In this embodiment, the mounting surface 22p is a surface perpendicular to the axial direction. As shown in FIG. 6, the mounting surface 22p is located on the rear side (-Z side) of the rotor main body 23. The mounting surface 22p contacts the rear-side surface of the rotor main body 23. That is, each of the multiple first arms 22 contacts the rear-side surface of the rotor main body 23 at the surface of the first arm 22 facing the front side, i.e., the mounting surface 22p. Therefore, the rotor main body 23 can be positioned axially with respect to the first rotor frame 21 by the first arms 22. Therefore, the axial position of the rotor body 23 relative to the stator 50 can be determined with high accuracy. In this embodiment, the mounting surface 22p contacts the rear surface of the rotor body 23, so the rotor body 23 can be supported more stably by the first arms 22. Note that each of the multiple first arms 22 may contact the rear surface of the rotor body 23 at the circumferential edge of the first arm 22. Even in this case, the rotor body 23 can be positioned in the axial direction relative to the first rotor frame 21 by the first arms 22.

[0031] The retaining wall 22g has a retaining surface 22t. That is, the multiple first arms 22 have a retaining surface 22t. The retaining surface 22t is a radially inner surface of the retaining wall 22g. The retaining surface 22t faces radially inward. In this embodiment, the retaining surface 22t is a surface perpendicular to the radial direction. The retaining surface 22t is located radially outward of the rotor body 23. More specifically, the retaining surface 22t is located radially outward of an annular member 23a (described later) of the rotor body 23. As shown in FIG. 10 , in this embodiment, the retaining surface 22t has an arc shape centered on the central axis J in a plan view along the axial direction. Note that in this specification, the "center of the arc" refers to the center of a circle formed by virtually extending the arc. The retaining surface 22t contacts the outer peripheral surface of the rotor body 23. Therefore, the rotor body 23 can be positioned radially relative to the first rotor frame 21 by the retaining surface 22t. This improves the radial positioning accuracy of the rotor body 23. Therefore, it is easy to arrange the magnets 23t (described later) of the rotor body 23 with high radial positional accuracy relative to the stator 50.

[0032] The first protrusion 22h is disposed on the front side (+Z side) of the arm main body 22f with a gap therebetween. The rear side (-Z side) surface of the first protrusion 22h faces the radially outer end of the mounting surface 22p with a gap therebetween in the axial direction. The radially inner surface of the first protrusion 22h has an arc shape centered on the central axis J in a plan view along the axial direction. The circumferential dimension of the first protrusion 22h is the same as the circumferential dimension of the holding wall 22g. As shown in FIG. 6, the first protrusion 22h is located radially outward of a magnet assembly 23b (described later) of the rotor main body 23.

[0033] As shown in FIG. 10 , each first arm 22 has a groove 22q recessed from the mounting surface 22p toward the rear. The groove 22q extends in the circumferential direction. Both circumferential ends of the groove 22q are provided at both circumferential edge portions of the mounting surface 22p. The groove 22q opens on both circumferential sides. The axial dimension of the groove 22q is smaller than the radial dimension of the groove 22q. The groove 22q is located radially inward from the radially inner end of the first protrusion 22h. The groove 22q is provided radially outward from the radially inner end of the mounting surface 22p. A plurality of grooves 22q are provided at intervals in the radial direction. In this embodiment, two grooves 22q are provided on each first arm 22.

[0034] As shown in FIG. 8 , in this embodiment, twelve first arms 22 are provided. The multiple first arms 22 include first arms 22a and first arms 22b. The first arms 22a and the first arms 22b are provided alternately, one by one, along the circumferential direction. In this embodiment, six first arms 22a and six first arms 22b are provided. Note that the number of first arms 22a and the number of first arms 22b are not particularly limited. It is also possible that no first arms 22a are provided and all first arms 22 are first arms 22b, or that no first arms 22b are provided and all first arms 22 are first arms 22a.

[0035] As shown in FIG. 10 , the first arm 22a has a second protruding wall 22s that protrudes toward the front side (+Z side) from a portion of the arm main body 22f that is located radially inward relative to the retaining wall 22g. In this embodiment, the second protruding wall 22s protrudes toward the front side from a radially inner end of the arm main body 22f. The second protruding wall 22s has a generally rectangular parallelepiped shape that is elongated in the radial direction. A radially inner end of the second protruding wall 22s is connected to an end of the first protruding wall 21b on one circumferential side. The second protruding wall 22s is located radially inward relative to the first protruding portion 22h. The circumferential dimension of the second protruding wall 22s is the same as the circumferential dimension of a portion of the arm main body 22f of the first arm 22a that is connected to the rear side (-Z side) of the second protruding wall 22s.

[0036] The first arm 22a has a mounting portion 22v. The mounting portion 22v is a front side (+Z side) portion of the arm main body portion 22f of the first arm 22a that is located radially outward from the second protruding wall 22s. The front side surface of the mounting portion 22v is the mounting surface 22p of the first arm 22a. The radially inner end of the mounting portion 22v is a narrow width portion 22w whose circumferential dimension decreases as it moves radially inward. Both circumferential side surfaces of the narrow width portion 22w approach each other in the circumferential direction as they move radially inward. Both circumferential side surfaces of the narrow width portion 22w are arc-shaped and recessed radially outward in a plan view along the axial direction. The circumferential dimension of mounting portion 22v is larger than the circumferential dimension of a portion of arm main body 22f of first arm 22a that is connected to the rear side (-Z side) of mounting portion 22v and the circumferential dimension of a portion that is connected to the rear side of second protruding wall 22s, excluding the radially inner end of narrow width portion 22w. Mounting portion 22v protrudes on both circumferential sides from the front-side end of the portion of arm main body 22f of first arm 22a that is connected to the rear side of mounting portion 22v.

[0037] The first arm 22a has a threaded hole 22r recessed from the mounting surface 22p toward the rear side (-Z side). In this embodiment, the threaded hole 22r is provided at the radially inner end of a portion of the mounting portion 22v that is located radially outer than the narrow width portion 22w. The threaded hole 22r is located radially inner than the groove 22q.

[0038] The first arm 22b has a third protruding wall 22i. The third protruding wall 22i is a protruding wall that protrudes toward the front side (+Z side) from a portion of the arm main body portion 22f that is located radially inward from the retaining wall 22g. In this embodiment, the third protruding wall 22i protrudes toward the front side from the radially inner end of the arm main body portion 22f. The third protruding wall 22i has a generally rectangular parallelepiped shape that is elongated in the radial direction. The radially inner end of the third protruding wall 22i is connected to the other circumferential end of the first protruding wall 21b. In this embodiment, the second protruding wall 22s of the first arm 22a and the third protruding wall 22i of the first arm 22b are connected to both circumferential ends of the first protruding wall 21b, respectively. The third protruding wall 22i is located radially inward from the first protruding portion 22h. The circumferential dimension of the third protruding wall 22i is greater than the circumferential dimension of the second protruding wall 22s. 6, the third protruding wall 22i is located radially inside the rotor body 23. A radially outer surface of the third protruding wall 22i is disposed opposite the radially inside of an annular member 23a of the rotor body 23, which will be described later.

[0039] As shown in FIG. 10, the circumferential dimension of a front-side (+Z side) portion of the arm main body portion 22f of the first arm 22b is larger than the circumferential dimension of a rear-side (-Z side) portion of the arm main body portion 22f of the first arm 22b. The first arm 22b has a mounting portion 22x. The mounting portion 22x is a portion of the arm main body portion 22f of the first arm 22b that is located radially outward from the third protruding wall 22i in the front-side portion. The front surface of the mounting portion 22x is the mounting surface 22p of the first arm 22b. The circumferential dimension of the mounting portion 22x is larger than the circumferential dimension of a portion of the arm main body portion 22f of the first arm 22b that is connected to the rear side of the mounting portion 22x. The mounting portion 22x protrudes on both circumferential sides from the front-side end of the portion of the arm main body portion 22f of the first arm 22b that is connected to the rear side of the mounting portion 22x.

[0040] The first arm 22b has a second protrusion 22j that protrudes radially outward from the front-side (+Z side) end of the third protruding wall 22i. The second protrusion 22j is disposed on the front side of the arm main body 22f with a gap therebetween. The rear-side (-Z side) surface of the second protrusion 22j faces the radially inner end of the mounting surface 22p with a gap therebetween in the axial direction. The radially outer surface of the second protrusion 22j has an arc shape centered on the central axis J in a plan view along the axial direction. The circumferential dimension of the second protrusion 22j is the same as the circumferential dimension of the third protruding wall 22i. As shown in FIG. 6, the second protrusion 22j is located radially inside a magnet assembly 23b (described later) of the rotor main body 23.

[0041] 10, the multiple first arms 22b include a first arm 22c and a first arm 22d. The second protruding portion 22j in the first arm 22d is a second protruding portion 22k having a recessed portion 22m and a second through-portion 22n. That is, the second protruding portion 22j includes the second protruding portion 22k having the second through-portion 22n. The recessed portion 22m is recessed from the front-side (+Z side) surface of the second protruding portion 22k toward the rear-side (-Z side). The interior of the recessed portion 22m opens to the radially outer surface of the second protruding portion 22k. A radially inner portion of the inner edge of the recessed portion 22m has a semicircular arc shape recessed radially inward in a plan view along the axial direction.

[0042] The second through portion 22n penetrates the second protruding portion 22k in the axial direction. In this embodiment, the second through portion 22n is a hole that penetrates the inner surface of the recess 22m from a surface located on the rear side (-Z side) to the rear side surface of the second protruding portion 22k in the axial direction. The second through portion 22n has a circular shape in a plan view along the axial direction. The inner edge of the second through portion 22n has portions located on both sides in the circumferential direction.

[0043] The mounting portion 22x of the first arm 22d has a recess 22y recessed from the mounting surface 22p toward the rear side (-Z side). The recess 22y is provided in a portion of the mounting portion 22x that is located on the rear side of the second protrusion 22j. The recess 22y overlaps with the second through portion 22n in a plan view along the axial direction. As shown in FIG. 11, the inner surface of the recess 22y has a conical shape that is convex toward the rear side. The recess 22y is formed, for example, by cutting a portion of the mounting surface 22p with the tip of a drill when the second through portion 22n is formed by drilling.

[0044] As shown in Fig. 8, a pair of first arms 22d are provided radially sandwiching the central axis line J. In this embodiment, of the six first arms 22b, four first arms 22b excluding the pair of first arms 22d are first arms 22c. As shown in Fig. 10, first arm 22c has the same configuration as first arm 22d, except that first arm 22c is not provided with recesses 22m, 22y and second through portion 22n.

[0045] As shown in FIG. 12 , the rotor body 23 is annular and surrounds the central axis J. More specifically, the rotor body 23 is substantially annular, with its center coinciding with the central axis J in a plan view along the axial direction. The rotor body 23 includes an annular member 23a and a magnet assembly 23b. The annular member 23a is annular and surrounds the central axis J. More specifically, the annular member 23a is substantially annular, with its center coinciding with the central axis J in a plan view along the axial direction. The annular member 23a is plate-shaped, with its plate surface facing the axial direction. The annular member 23a is made of a magnetic material. Note that, in this specification, "an object made of a magnetic material" includes an object made of a ferromagnetic material. The annular member 23a is located on the rear side (-Z side) of the multiple magnets 23t that constitute the magnet assembly 23b. The rear surface of the annular member 23a is the rear surface of the rotor body 23.

[0046] As shown in Fig. 11, the annular member 23a is located on the front side (+Z side) of the mounting surface 22p of the multiple first arms 22. The rear side (-Z side) surface of the annular member 23a contacts the mounting surface 22p. The annular member 23a is located on the first arms 22b radially between the retaining wall 22g and the third protruding wall 22i. As shown in Fig. 8, the annular member 23a has an annular main body portion 23c, multiple outer protruding portions 23d, a first inner protruding portion 23e, and a second inner protruding portion 23f.

[0047] The annular main body portion 23c has an annular shape surrounding the central axis J. More specifically, the annular main body portion 23c has an annular shape whose center coincides with the central axis J in a plan view along the axial direction. As shown in FIG. 11 , the annular main body portion 23c is located on the front side (+Z side) of the mounting surfaces 22p of the multiple first arms 22. The rear side (-Z side) surface of the annular main body portion 23c contacts the mounting surface 22p. The annular main body portion 23c is fixed to each first arm 22, for example, via an adhesive provided in each groove 22q.

[0048] As shown in FIG. 8, the multiple outer protrusions 23d protrude radially outward from the outer peripheral edge of the annular main body portion 23c. The multiple outer protrusions 23d are arranged at intervals in the circumferential direction. The multiple outer protrusions 23d are arranged at equal intervals around the circumference in the circumferential direction. The number of outer protrusions 23d is the same as the number of first arms 22. That is, in this embodiment, 12 outer protrusions 23d are provided. Note that the number of outer protrusions 23d is not particularly limited as long as it is two or more. As shown in FIG. 13, the outer protrusions 23d have a substantially trapezoidal shape in a plan view along the axial direction, with the circumferential dimension decreasing radially outward. The radial dimension of the outer protrusions 23d is smaller than the circumferential dimension of the outer protrusions 23d. The radial outer edge of the outer protrusions 23d has an arc shape whose center coincides with the central axis J in a plan view along the axial direction.

[0049] As shown in FIG. 14, the multiple outer protrusions 23d are located on the rear side (-Z side) of the first protrusions 22h of the multiple first arms 22. Each outer protrusion 23d is located axially between each arm main body 22f and each first protrusion 22h. The circumferential dimension of each outer protrusion 23d is greater than the circumferential dimension of each first arm 22. As shown in FIG. 11, the radial outer edges of the multiple outer protrusions 23d contact the holding surface 22t. Therefore, the annular member 23a is radially positioned relative to the first rotor frame 21. Because the portion of the rotor main body 23 that contacts the holding surface 22t is the annular member 23a, load on the magnets 23t can be reduced compared to when the magnets 23t constituting the magnet assembly 23b contact the holding surface 22t. This reduces damage to the magnets 23t.

[0050] Each outer protrusion 23d contacts the rear-side (-Z side) surface of each first protrusion 22h. Therefore, each outer protrusion 23d is prevented from moving toward the front side (+Z side). This prevents the annular member 23a from moving toward the front side, thereby preventing the rotor body 23 from coming off the first rotor frame 21 in the axial direction. Furthermore, since the annular member 23a, rather than the magnets 23t constituting the magnet assembly 23b, can be held down by the rear-side surface of the first protrusion 22h, the magnets 23t are further prevented from being subjected to a load. This further prevents the magnets 23t from being damaged. Each outer protrusion 23d may face the rear-side surface of each first protrusion 22h with a gap therebetween. Even in this case, when the outer protrusion 23d attempts to move toward the front side, the outer protrusion 23d gets caught on the first protrusion 22h from the rear side. This prevents the rotor body 23 from coming off the first rotor frame 21 in the axial direction. The rear surface of the outer protrusion 23d contacts the mounting surface 22p.

[0051] As shown in FIG. 8 , the first inner protrusion 23e and the second inner protrusion 23f protrude radially inward from the inner circumferential edge of the annular main body 23c. In this embodiment, a plurality of first inner protrusions 23e and a plurality of second inner protrusions 23f are provided. The first inner protrusions 23e and the second inner protrusions 23f are provided alternately at intervals in the circumferential direction. The plurality of inner protrusions, including the plurality of first inner protrusions 23e and the plurality of second inner protrusions 23f, are arranged at equal intervals around the circumference. The plurality of inner protrusions, including the plurality of first inner protrusions 23e and the plurality of second inner protrusions 23f, are provided radially inward of the plurality of outer protrusions 23d. The total number of the first inner protrusions 23e and the number of the second inner protrusions 23f is the same as the number of first arms 22. In this embodiment, six first inner protrusions 23e and six second inner protrusions 23f are provided. The number of first inner protrusions 23e and the number of second inner protrusions 23f are not particularly limited as long as they are one or more.

[0052] 13, the first inner protrusion 23e has a generally trapezoidal shape in which the circumferential dimension decreases radially inward in a plan view along the axial direction. The radial dimension of the first inner protrusion 23e is smaller than the circumferential dimension of the first inner protrusion 23e. The maximum circumferential dimension of the first inner protrusion 23e is the same as the maximum circumferential dimension of the outer protrusion 23d, for example. The radial inner edge of the first inner protrusion 23e has an arc shape whose center coincides with the central axis J in a plan view along the axial direction.

[0053] As shown in FIG. 14 , each first inner protrusion 23e is located on the rear side (−Z side) of each second protrusion 22j of each first arm 22b. Each first inner protrusion 23e is located axially between each arm main body 22f and each second protrusion 22j of each first arm 22b. The circumferential dimension of each first inner protrusion 23e is greater than the circumferential dimension of each first arm 22b. Each first inner protrusion 23e contacts the rear-side surface of each second protrusion 22j. Therefore, each first inner protrusion 23e is prevented from moving toward the front side (+Z side). This further prevents the annular member 23a from moving toward the front side, and further prevents the annular member 23a from coming off the first rotor frame 21 in the axial direction. Each first inner protrusion 23e may face the rear-side surface of each second protrusion 22j with a gap therebetween. Even in this case, when the first inner protrusion 23e attempts to move toward the front side, the first inner protrusion 23e gets caught on the second protrusion 22j from the rear side, which further prevents the annular member 23a from coming off the first rotor frame 21 in the axial direction. The rear-side surface of the first inner protrusion 23e comes into contact with the mounting surface 22p.

[0054] 8, the multiple first inner protrusions 23e include a first inner protrusion 23g and a first inner protrusion 23h. A pair of first inner protrusions 23h are provided radially on either side of the central axis J. In this embodiment, of the six first inner protrusions 23e, four first inner protrusions 23e excluding the pair of first inner protrusions 23h are first inner protrusions 23g. The first inner protrusions 23g have the same configuration as the first inner protrusions 23h, except that they do not have a first through portion 23i, which will be described later.

[0055] As shown in FIG. 13, the first inner protruding portion 23h has a first through portion 23i that penetrates the first inner protruding portion 23h in the axial direction. In this embodiment, the first through portion 23i is a recess that is recessed radially outward from a circumferential center portion of the radial inner edge of the first inner protruding portion 23h. As shown in FIG. 15, the inner edge of the first through portion 23i has a pair of circumferential edge portions 23k, 23m and a radial outer edge portion 23n. The pair of circumferential edge portions 23k, 23m are portions of the inner edge of the first through portion 23i that are located on both circumferential sides. The pair of circumferential edge portions 23k, 23m extend in a radial direction that passes through the circumferential center of the first inner protruding portion 23h and are parallel to each other in a plan view along the axial direction. The radial outer edge portion 23n is a portion of the inner edge of the first through portion 23i that is located radially outward. The radially outer edge portion 23n has a semicircular arc shape recessed radially outward in a plan view along the axial direction, and connects the radially outer ends of the pair of circumferential edge portions 23k, 23m.

[0056] The first through portion 23i is located on the rear side (-Z side) of the second through portion 22n provided in the second protrusion 22k. The first through portion 23i and the second through portion 22n at least partially overlap each other when viewed in a plan view along the axial direction. In the present embodiment, the entire second through portion 22n overlaps with a portion of the first through portion 23i when viewed in a plan view along the axial direction. A pin member 26c extending in the axial direction is passed through the first through portion 23i and the second through portion 22n. In the present embodiment, the pin member 26c is a cylindrical member extending in the axial direction. In the present embodiment, the pin member 26c is passed through the second through portion 22n from the front side (+Z side) and inserted into the first through portion 23i from the front side. The pin member 26c contacts portions of the inner edge of the first through portion 23i located on both circumferential sides, i.e., portions of the inner edge of the pair of circumferential edge portions 23k, 23m and the second through portion 22n located on both circumferential sides. Therefore, the first inner protruding portion 23h and the second protruding portion 22k are circumferentially positioned via the pin member 26c. This positions the annular member 23a relative to the first rotor frame 21 in the circumferential direction. Therefore, circumferential displacement of the annular member 23a relative to the first rotor frame 21 is suppressed. In this embodiment, the pin member 26c is press-fitted into the first through portion 23i and the second through portion 22n. As shown in FIG. 11 , the rear end of the pin member 26c contacts the peripheral edge of the recess 22y on the mounting surface 22p.

[0057] As shown in FIG. 13, the circumferential dimension of the second inner protrusion 23f decreases radially inward. The radial dimension of the second inner protrusion 23f is smaller than the maximum circumferential dimension of the second inner protrusion 23f. The maximum circumferential dimension of the second inner protrusion 23f is, for example, the same as the maximum circumferential dimension of the outer protrusion 23d. The radial inner edge of the second inner protrusion 23f has an arc portion 23j that is arc-shaped and recessed radially outward in a plan view along the axial direction. In this embodiment, the arc portion 23j is provided in the circumferential center of the radial inner edge of the second inner protrusion 23f.

[0058] As shown in Fig. 14, each second inner protrusion 23f is located on the front side (+Z side) of the arm main body 22f of each first arm 22a. The maximum circumferential dimension of each second inner protrusion 23f is greater than the circumferential dimension of each first arm 22a. In a plan view along the axial direction, the arc portion 23j is located at a position that substantially overlaps with a portion of the inner edge of the screw hole 22r provided in the first arm 22a that is located on the radially outer side. As shown in Fig. 16, the rear side (-Z side) surface of the second inner protrusion 23f contacts the mounting surface 22p of the first arm 22a.

[0059] As shown in FIG. 12 , the magnet assembly 23b is annular and surrounds the central axis J. More specifically, the magnet assembly 23b is annular and has a center coincident with the central axis J in a plan view along the axial direction. The magnet assembly 23b is configured by combining a plurality of magnets 23t. In other words, the rotor body 23 includes a plurality of magnets 23t. The magnet assembly 23b is located on the front side (+Z side) of the annular member 23a. The magnet assembly 23b is fixed to the front surface of the annular member 23a. More specifically, the magnet assembly 23b is fixed to the front surface of the annular main body portion 23c of the annular member 23a. In other words, the plurality of magnets 23t are fixed to the annular main body portion 23c. The plurality of magnets 23t are fixed to the annular main body portion 23c via, for example, an adhesive. The inner peripheral edge of the magnet assembly 23b is located radially outward of the inner peripheral edge of the annular main body portion 23c. The outer peripheral edge of the magnet assembly 23b is located radially outward of the outer peripheral edge of the annular main body portion 23c.

[0060] The magnet assembly 23b includes a plurality of first magnet assemblies 23p and a plurality of second magnet assemblies 23q. The first magnet assemblies 23p and the second magnet assemblies 23q are arranged alternately along the circumferential direction. The first magnet assemblies 23p and the second magnet assemblies 23q that are adjacent to each other in the circumferential direction are in contact with each other. When viewed in a plan view along the axial direction, the first magnet assembly 23p has a generally trapezoidal shape whose circumferential dimension decreases radially inward. When viewed in a plan view along the axial direction, the second magnet assembly 23q has a generally rectangular shape that is long in the radial direction. The circumferential dimension of the second magnet assembly 23q is smaller than the circumferential dimension of the first magnet assembly 23p.

[0061] In this embodiment, each first magnet assembly 23p is formed by combining a plurality of first magnets 23r arranged in the radial direction. In this embodiment, each second magnet assembly 23q is formed by combining a plurality of second magnets 23s arranged in the radial direction. That is, the plurality of magnets 23t includes a plurality of first magnets 23r and a plurality of second magnets 23s. Each first magnet assembly 23p is formed by five first magnets 23r connected in the radial direction. Each second magnet assembly 23q is formed by five second magnets 23s connected in the radial direction. The five first magnets 23r constituting one first magnet assembly 23p are connected to the five second magnets 23s constituting each second magnet assembly 23q arranged adjacent to each other on both circumferential sides of the first magnet assembly 23p. In this embodiment, the magnet assembly 23b is configured with five annular magnet assemblies 23u arranged radially, each of which is made up of a first magnet 23r and a second magnet 23s arranged alternately in the circumferential direction. The outer diameters of the annular magnet assemblies 23u located radially outward are larger.

[0062] The magnetization direction of at least some or all of the multiple magnets 23t is axial. In this embodiment, the magnetization direction of some of the multiple magnets 23t is axial. The magnetization direction of the multiple first magnets 23r is axial. The magnetization direction of the multiple second magnets 23s is a direction that intersects the axial direction. The magnetization direction of the multiple second magnets 23s is, for example, a direction inclined circumferentially with respect to the axial direction. In each annular magnet assembly 23u, the magnetization directions of the two second magnets 23s arranged circumferentially on either side of one first magnet 23r are, for example, directions inclined toward different circumferential sides with respect to the axial direction.

[0063] In this embodiment, the multiple magnets 23t constituting the magnet assembly 23b are arranged in a Halbach array. The Halbach array in which the multiple magnets 23t are arranged is an array that can maximize the magnetic field strength toward the axial side where the stator 50 is located relative to the first rotor 20, i.e., the front side (+Z side). In each of the five annular magnet assemblies 23u constituting the magnet assembly 23b, the multiple first magnets 23r and the multiple second magnets 23s are arranged in a Halbach array along the circumferential direction. By arranging the multiple magnets 23t in a Halbach array, the magnetic flux density of the magnetic flux flowing between the first rotor 20 and the stator 50 can be increased, thereby improving the output torque of the motor 100. The multiple magnets 23t may be bonded to each other, for example, with an adhesive. Note that the multiple magnets 23t do not have to be arranged in a Halbach array. The magnetization direction of all the magnets 23t may be axial.

[0064] As shown in FIG. 8 , the first cover 24 is annular and surrounds the central axis J. More specifically, the first cover 24 is substantially annular and has a center coincident with the central axis J in a plan view along the axial direction. The first cover 24 is fixed to the first rotor frame 21. The first cover 24 is located on the front side (+Z side) of the magnet assembly 23b. The first cover 24 covers at least a portion of the surface of the magnet 23t facing the front side. Therefore, the first cover 24 can prevent the magnet 23t from moving axially toward the front side (+Z side), i.e., toward the side of the first rotor 20 where the stator 50 is located. This prevents the magnet 23t from coming into contact with the stator 50. This improves the operational stability of the motor 100. Furthermore, because the magnet 23t can be prevented from moving toward the stator 50, when determining the size of the gap between the first rotor 20 and the stator 50 in the axial direction, i.e., the air gap, it is not necessary to increase the air gap in consideration of the axial movement of the magnet 23t. This makes it easier to reduce the air gap and increase the magnetic force generated between the magnet 23t and the stator 50. This makes it easier to improve the output torque of the motor 100.

[0065] In the present embodiment, the first cover 24 covers the entire surfaces of the magnets 23t constituting the magnet assembly 23b facing the front side (+Z side), which can further prevent the magnets 23t from moving to the front side and from contacting the stator 50.

[0066] As shown in FIG. 17 , the first cover 24 has an annular portion 24a and a fixed portion 24b. When viewed in a plan view along the axial direction, the annular portion 24a is annular and surrounded by two concentric circles C1 and C2. The two concentric circles C1 and C2 are imaginary circles indicated by dashed lines in FIG. 17 . When viewed in a plan view along the axial direction, the centers of the two concentric circles C1 and C2 coincide with the central axis J. The diameter of the concentric circle C2 is larger than the diameter of the concentric circle C1. The inner peripheral edge of the annular portion 24a overlaps with the concentric circle C1 when viewed in a plan view along the axial direction. The outer peripheral edge of the annular portion 24a overlaps with the concentric circle C2 when viewed in a plan view along the axial direction. When the difference between the radii of the two concentric circles C1 and C2 is referred to as the width of the annular portion 24a, as shown in FIG. 8 , the width of the annular portion 24a is larger than the axial height of the entire first cover 24. The width of the annular portion 24a is the radial distance between the inner peripheral edge of the annular portion 24a and the outer peripheral edge of the annular portion 24a.

[0067] As shown in FIG. 16, the annular portion 24a has a first top panel portion 24c, an inner wall 24d, an outer wall 24e, and a flange portion 24f. That is, the first cover 24 has the first top panel portion 24c, the inner wall 24d, the outer wall 24e, and the flange portion 24f. The first top panel portion 24c is located on the front side (+Z side) of the magnet assembly 23b. The first top panel portion 24c is a top panel portion that covers at least a portion of the surfaces of the plurality of magnets 23t that face the front side. In this embodiment, the first top panel portion 24c covers the entire surfaces of the plurality of magnets 23t that face the front side, which constitute the magnet assembly 23b. The first top panel portion 24c is plate-shaped, with the plate surface facing the axial direction. The rear side (-Z side) surface of the first top panel portion 24c faces the surfaces of the plurality of magnets 23t that face the front side in the axial direction, with a gap between them. The rear surface of the first top panel portion 24c may be in contact with the surfaces of the plurality of magnets 23t facing the front side. As shown in Fig. 17, the first top panel portion 24c has an annular shape surrounding the central axis line J. More specifically, the first top panel portion 24c has a substantially annular shape whose center coincides with the central axis line J in a plan view along the axial direction.

[0068] As shown in FIG. 7, the inner wall 24d protrudes from the inner peripheral edge of the first top plate portion 24c toward the rear side (-Z side). The inner wall 24d is cylindrical and surrounds the central axis J. More specifically, the inner wall 24d is substantially cylindrical, the center of which coincides with the central axis J in a plan view along the axial direction. As shown in FIG. 16, the inner wall 24d is located radially inward of the rotor body 23. In this embodiment, the inner wall 24d is located radially inward of the magnet assembly 23b. The outer peripheral surface of the inner wall 24d faces the radially inner side of the inner peripheral surface of the magnet assembly 23b via a gap. The outer peripheral surface of the inner wall 24d may be in contact with the inner peripheral surface of the magnet assembly 23b. The outer peripheral surface of the inner wall 24d is located radially inward of the inner peripheral edge of the annular main body portion 23c.

[0069] The rear end (-Z side) of the inner wall 24d is located on the front side (+Z side) of the annular member 23a. More specifically, the rear end of the inner wall 24d is located on the front side of the first inner protrusions 23e and the second inner protrusions 23f. As shown in Fig. 18, an axial recess 24r recessed toward the front side is provided in a portion of the rear end of the inner wall 24d that is not connected to the fixed portion 24b.

[0070] The inner wall 24d has a radial recess 24n on its inner circumferential surface, recessed radially outward. The radial recess 24n extends in the axial direction from the front end (+Z side) of the inner wall 24d to the rear end (-Z side). In a plan view along the axial direction, the inner edge of the radial recess 24n has an arc shape recessed radially outward. The radial recess 24n is provided at the same circumferential position as a through hole 24g (described later) provided in the fixed portion 24b.

[0071] As shown in FIG. 7, the outer wall 24e protrudes from the outer peripheral edge of the first top plate portion 24c toward the rear side (-Z side). The outer wall 24e is cylindrical and surrounds the central axis J. More specifically, the outer wall 24e is cylindrical and centered on the central axis J. As shown in FIG. 16, the outer wall 24e is located radially outward of the rotor body 23. In this embodiment, the outer wall 24e is located radially outward of the magnet assembly 23b. The inner peripheral surface of the outer wall 24e faces the outer peripheral surface of the magnet assembly 23b across a gap. The inner peripheral surface of the outer wall 24e may be in contact with the outer peripheral surface of the magnet assembly 23b. The inner peripheral surface of the outer wall 24e is located radially outward of the outer peripheral edge of the annular main body portion 23c. The outer wall 24e is located on the front side (+Z side) of the first protrusion 22h.

[0072] As shown in Fig. 7, the flange portion 24f protrudes radially outward from the rear-side (-Z side) end of the outer wall 24e. The flange portion 24f is annular and surrounds the central axis J. More specifically, the flange portion 24f is annular and has a center that coincides with the central axis J in a plan view along the axial direction. As shown in Fig. 16, the rear-side surface of the flange portion 24f is located on the front side (+Z side) of the retaining wall 22g.

[0073] The first cover 24 has a first cover recess 24t on the rear side (-Z side). The first cover recess 24t is a portion configured such that the central portion in the width direction of the annular portion 24a is recessed toward the front side (+Z side). The first cover recess 24t is configured by a first top plate portion 24c, an inner wall 24d, and an outer wall 24e. The first cover recess 24t extends along the annular portion 24a, surrounding the central axis J. By providing the first cover recess 24t, it is possible to accommodate the magnet assembly 23b within the first cover recess 24t, while providing a portion for fixing the first cover 24 to the first rotor frame 21 on the radially inner or radially outer side of the annular portion 24a. In this embodiment, the fixed portion 24b is provided on the radially inner side of the annular portion 24a. Since the fixed portion 24b can be disposed rearward of the front end of the ring-shaped portion 24a, even when the fixed portion 24b is fixed with the bolt 26b, the head 26e of the bolt 26b can be prevented from protruding forward beyond the front end of the first cover 24. In this embodiment, the front portion of the magnet assembly 23b is located within the first cover recess 24t.

[0074] As shown in FIG. 7, the first cover 24 has a plurality of accommodating recesses 24s recessed from the rear-side (-Z side) end of the outer wall 24e and the rear-side end of the flange portion 24f toward the front side (+Z side). The plurality of accommodating recesses 24s are spaced apart in the circumferential direction. The number of accommodating recesses 24s is the same as the number of first arms 22. As shown in FIG. 16, the interior of each accommodating recess 24s opens radially inward and outward. The front-side portions of the retaining walls 22g and the first protrusions 22h of the first arms 22 are located inside each accommodating recess 24s. The front-side inner surfaces of each accommodating recess 24s contact the front-side surfaces of the retaining walls 22g and the first protrusions 22h. The front-side inner surfaces of each accommodating recess 24s are fixed to the retaining walls 22g and the first protrusions 22h, for example, with an adhesive or the like.

[0075] As shown in FIG. 7, the fixed portion 24b protrudes radially inward from the rear-side (-Z side) end of the inner wall 24d. The fixed portion 24b extends in the circumferential direction. A plurality of the fixed portions 24b are provided at intervals in the circumferential direction. In this embodiment, six fixed portions 24b are provided. The circumferential center portion of each fixed portion 24b is located on the front side (+Z side) of the first arm 22a. Each fixed portion 24b is respectively located between two first arms 22b that are arranged with the first arm 22a sandwiched between them in the circumferential direction. As shown in FIG. 18, the fixed portion 24b has a recess 24j recessed from the front-side surface of the fixed portion 24b toward the rear side. The recess 24j is provided in the circumferential center portion of the fixed portion 24b. The interior of the recess 24j opens radially inward. The radially outer end of the recess 24j is connected to a radial recess 24n provided in the inner wall 24d.

[0076] The fixed portion 24b has a through hole 24g that penetrates the fixed portion 24b in the axial direction. The through hole 24g is provided in the circumferential center of the fixed portion 24b. The through hole 24g is provided in the recess 24j. The through hole 24g opens to a surface of the inner surface of the recess 24j that is located on the rear side (-Z side). The through hole 24g has a first hole portion 24h and a second hole portion 24i. The first hole portion 24h is a radially inner portion of the through hole 24g. The first hole portion 24h has an arc-shaped inner edge that is recessed radially inward in a plan view along the axial direction. The inner edge of the first hole portion 24h has an arc-shaped shape with a central angle greater than 180° in a plan view along the axial direction.

[0077] The second hole portion 24i is located radially outward of the first hole portion 24h. The second hole portion 24i is connected to the first hole portion 24h. The circumferential dimension of the second hole portion 24i is larger than the circumferential dimension of the first hole portion 24h. As shown in FIG. 19, the second hole portion 24i has a first opening 24p and a second opening 24q. The first opening 24p is an opening on the front side (+Z side) of the second hole portion 24i. As shown in FIG. 18, the first opening 24p opens on a surface located on the rear side (-Z side) of the inner surface of the recess 24j. A portion of the inner edge of the first opening 24p located radially outward has an arc shape recessed radially outward in a plan view along the axial direction.

[0078] As shown in FIG. 19 , the second opening 24q is an opening on the rear side (−Z side) of the second hole portion 24i. The radially outer end of the second opening 24q is located radially outward of the radially outer end of the first opening 24p. The second opening 24q is provided across the fixed portion 24b and the inner wall 24d. The second opening 24q opens to the rear-side surface of the fixed portion 24b, the rear-side surface of the inner wall 24d, and the outer peripheral surface of the inner wall 24d. The second hole portion 24i opens to the radially outer surface of the inner wall 24d at the second opening 24q. The entire second hole portion 24i, except for the first opening 24p, opens to the radially outer surface of the inner wall 24d. The circumferential dimension of the second opening 24q increases radially outward. At least a portion of the second inner protrusion 23f is located in the second hole portion 24i. In this embodiment, the entire second inner protrusion 23f is positioned in the second hole 24i.

[0079] As shown in FIG. 20 , a radially outer portion of the second inner protrusion 23f located within the second hole portion 24i overlaps with the first opening 24p in a plan view along the axial direction. The front-side (+Z side) surface of the second inner protrusion 23f is located at the same axial position as a rear-side (-Z side) surface of the inner surface of the recess 24j. The arc portion 23j provided on the radially inner edge of the second inner protrusion 23f is located radially outside the first hole portion 24h. The inner edge of the first hole portion 24h and the arc portion 23j form a bolt through hole 26f through which the bolt 26b is inserted from the front side. The bolt through hole 26f has a circular shape in a plan view along the axial direction. As shown in FIG. 16 , the bolt 26b is inserted through the bolt through hole 26f and screwed into a threaded hole 22r provided in the first arm 22a. The fixed portion 24b is fixed to the first arm 22a with the bolt 26b.

[0080] The bolt 26b has a threaded portion 26d that engages with the threaded portion of the threaded hole 22r and a head 26e that connects to the front (+Z) end of the threaded portion 26d. The threaded portion 26d extends in the axial direction. The threaded portion 26d is axially passed through the bolt through-hole 26f from the front side and screwed into the threaded hole 22r. The outer diameter of the head 26e is larger than that of the threaded portion 26d. As shown in FIG. 20 , the head 26e is located on the front side of the portion of the fixed portion 24b where the recess 24j is provided and the portion of the second inner protruding portion 23f located in the second hole portion 24i that axially overlaps with the first opening 24p. The head 26e of the bolt 26b presses the fixed portion 24b and the second inner protruding portion 23f against the first arm 22a from the front side. Therefore, the fixed portion 24b and the second inward protruding portion 23f are fixed to the first arm 22a by the bolt 26b. This allows the first cover 24 and the annular member 23a to be firmly fixed to the first arm 22a, and axial movement of the first cover 24 and the rotor body 23 relative to the first rotor frame 21 can be preferably suppressed. Furthermore, because the annular member 23a can be fixed to the first arm 22a using the bolt 26b that secures the first cover 24 to the first arm 22a, there is no need to provide a separate bolt for securing the annular member 23a to the first arm 22a. This prevents an increase in the number of parts of the motor 100. By securing the annular member 23a to the first arm 22a, the multiple magnets 23t secured to the annular member 23a are indirectly secured to the first rotor frame 21. As shown in FIG. 16, the rear side (-Z side) surface of the fixed portion 24b comes into contact with the mounting surface 22p of the first arm 22a.

[0081] An annular washer 26g surrounding the threaded portion 26d is provided between the head 26e and the fixed portion 24b and the second inner protrusion 23f in the axial direction. In this embodiment, the washer 26g is a wave washer. The washer 26g contacts the rear-side (-Z side) surface of the inner surface of the recess 24j, the front-side (+Z side) surface of the second inner protrusion 23f, and the rear-side surface of the head 26e. The washer 26g is elastically deformed by being pressed toward the rear side by the head 26e. Because the washer 26g is a wave washer, the elastic force of the washer 26g can be used to more firmly press the fixed portion 24b and the second inner protrusion 23f against the first arm 22a. The head 26e is located inside the recess 24j. By providing the recess 24j, the head 26e can be more effectively prevented from being positioned further forward than the front end of the first cover 24.

[0082] As shown in FIG. 18 , the fixed portion 24b has a hook portion 24k on its radially inner edge. The hook portion 24k is located radially outward of a portion of the radially inner edge of the fixed portion 24b other than the portion where the hook portion 24k is provided. The hook portion 24k extends in the circumferential direction. The hook portion 24k has a hook surface 24m facing the front side (+Z side). The hook surface 24m is located closer to the rear side (-Z side) than the front-side surfaces of a portion of the fixed portion 24b adjacent to the radially outer side of the hook portion 24k and portions adjacent to both circumferential sides of the hook portion 24k. The hook surface 24m extends in the circumferential direction. The hook surface 24m is a surface perpendicular to the axial direction. In this embodiment, two hook portions 24k are provided on one fixed portion 24b. One hook portion 24k is provided on a portion of the fixed portion 24b that is located on one circumferential side of the through hole 24g, and the other hook portion 24k is provided on a portion of the fixed portion 24b that is located on the other circumferential side of the through hole 24g.

[0083] The first cover 24 is made of a non-magnetic material. In this embodiment, the first cover 24 is made of resin. More specifically, the first cover 24 is made of fiber-reinforced plastic. Therefore, the rigidity of the first cover 24 can be improved while preventing the mass of the first cover 24 from increasing. This improves the rigidity of the first rotor 20, and prevents the first rotor 20 from bending in the axial direction even when a magnetic force acts between the first rotor 20 and the stator 50. Therefore, it is possible to prevent the axial distance between the first rotor 20 and the stator 50 from fluctuating, and stabilize the magnetic force acting between the first rotor 20 and the stator 50. Examples of fiber-reinforced plastics that form the first cover 24 include carbon fiber reinforced plastics (CFRP).

[0084] As shown in FIG. 8, the multiple second covers 25 are disposed on the rear side (-Z side) of the rotor body 23. The multiple second covers 25 are disposed at intervals in the circumferential direction. The multiple second covers 25 are disposed at equal intervals around the circumference. As shown in FIG. 14, the multiple second covers 25 are respectively positioned between the first arms 22 adjacent to each other in the circumferential direction. Each second cover 25 contacts the first arms 22 adjacent to each other on both sides in the circumferential direction. Note that each second cover 25 does not have to contact the first arms 22 adjacent to each other on both sides in the circumferential direction. As shown in FIG. 21, each second cover 25 covers at least a portion of the rear-side surface of the rotor body 23. In this embodiment, each second cover 25 covers the rear-side surface of each portion of the annular member 23a that is positioned between the first arms 22 adjacent to each other in the circumferential direction. In this embodiment, the entire rear surface of the rotor body 23 is covered by the multiple first arms 22 and the multiple second covers 25. The second cover 25 is fixed to the first cover 24. The provision of the second cover 25 further improves the rigidity of the first rotor 20. This further improves the rigidity of the first rotor 20, and makes it possible to more effectively prevent the first rotor 20 from bending in the axial direction even when a magnetic force acts between the first rotor 20 and the stator 50. Therefore, it is possible to more effectively prevent the axial distance between the first rotor 20 and the stator 50 from fluctuating, and it is possible to more effectively stabilize the magnetic force acting between the first rotor 20 and the stator 50. Note that the second cover 25 may be fixed to the first rotor frame 21 instead of the first cover 24, or may be fixed to both the first rotor frame 21 and the first cover 24. Even in this case, it is possible to further improve the rigidity of the first rotor 20, and it is possible to more effectively stabilize the magnetic force acting between the first rotor 20 and the stator 50.

[0085] The second cover 25 is made of a non-magnetic material. In this embodiment, the second cover 25 is made of resin. More specifically, the second cover 25 is made of fiber-reinforced plastic. This makes it possible to improve the rigidity of the second cover 25 while preventing the mass of the second cover 25 from increasing. This further improves the rigidity of the first rotor 20, and prevents the first rotor 20 from bending in the axial direction. This further prevents the axial distance between the first rotor 20 and the stator 50 from fluctuating, and makes it possible to further stabilize the magnetic force acting between the first rotor 20 and the stator 50. An example of the fiber-reinforced plastic that makes up the second cover 25 is carbon fiber-reinforced plastic.

[0086] As shown in FIG. 22 , the second cover 25 has a bottom plate portion 25a, a fixed wall 25b, and a claw 25c. The bottom plate portion 25a has a fan shape centered on the central axis J in a plan view along the axial direction. In this specification, the “center of the fan shape” refers to the center of a circle formed by imaginarily extending the arc portion of the fan shape. In this specification, the “fan shape” includes a shape surrounded by two arcs with the same center of curvature but different radii and two line segments extending in the radial direction of a circle centered on the center of curvature and connecting the two ends of the two arcs. In this embodiment, the bottom plate portion 25a has a shape surrounded by two arcs with the same center of curvature but different radii and two line segments extending in the radial direction of a circle centered on the center of curvature and connecting the two ends of the two arcs in a plan view along the axial direction. The circumferential dimension of the bottom plate portion 25a increases radially outward. 21, the bottom plate portion 25a covers a part of the rear-side (-Z side) surface of the rotor body 23. The front-side (+Z side) surface of the bottom plate portion 25a contacts the rear-side surface of the annular main body portion 23c of the annular member 23a.

[0087] The fixed wall 25b protrudes from the radial outer edge of the bottom plate portion 25a to the front side (+Z side) toward the first cover 24. The fixed wall 25b is located radially outside the rotor body 23. In this embodiment, the fixed wall 25b is located radially outside the annular main body portion 23c. The fixed wall 25b faces the radial outer edge of the annular main body portion 23c across a gap. The fixed wall 25b may be in contact with the radial outer edge of the annular main body portion 23c. In this embodiment, the front side surface of the fixed wall 25b is located at approximately the same position in the axial direction as the front side surface of the annular member 23a.

[0088] The front end face (+Z side) of the fixed wall 25b contacts the rear end face (-Z side) of the flange portion 24f. The front end face of the fixed wall 25b is fixed to the rear end face of the flange portion 24f. This fixes the fixed wall 25b to the first cover 24. By providing the fixed wall 25b, the rigidity of the second cover 25 can be improved. This further improves the rigidity of the first rotor 20, and axial deflection of the first rotor 20 can be further suppressed. Therefore, fluctuations in the axial distance between the first rotor 20 and the stator 50 can be further suppressed, and the magnetic force acting between the first rotor 20 and the stator 50 can be further stabilized. In this embodiment, as described above, the multiple second covers 25 are respectively positioned between the first arms 22 adjacent to each other in the circumferential direction. Therefore, the multiple second covers 25 further improve the rigidity of the first rotor 20. This makes it possible to further suppress fluctuations in the axial distance between the first rotor 20 and the stator 50, and to further stabilize the magnetic force acting between the first rotor 20 and the stator 50. The method for fixing the fixed wall 25b and the flange portion 24f is not particularly limited. The fixed wall 25b and the flange portion 24f may be fixed to each other with an adhesive or by welding.

[0089] As shown in FIG. 22, fixed wall 25b extends in the circumferential direction. Fixed wall 25b extends from one circumferential end to the other circumferential end of the radially outer edge of bottom plate portion 25a. Notches 25f, 25g recessed radially outward are provided at both circumferential ends of the radially inner edge of fixed wall 25b. As shown in FIG. 14, notches 25f, 25g are each located radially outward from the circumferential end of outer protrusion 23d and are arranged opposite the circumferential end of outer protrusion 23d. Providing notches 25f, 25g prevents fixed wall 25b from colliding with outer protrusion 23d.

[0090] As shown in FIG. 22 , the claw 25c protrudes from the radial inner edge of the bottom plate portion 25a toward the front side (+Z side). More specifically, the claw 25c protrudes from a circumferential center portion of the radial inner edge of the bottom plate portion 25a toward the front side. The circumferential dimension of the claw 25c is smaller than the circumferential dimension of the radial inner edge of the bottom plate portion 25a. The claw 25c has a base portion 25d and a claw main body portion 25e. The base portion 25d protrudes from the radial inner edge of the bottom plate portion 25a toward the front side. The base portion 25d is plate-shaped with its plate surface facing the radial direction. The base portion 25d is elastically deformable in the radial direction. The claw main body portion 25e protrudes radially outward from a front end portion of the base portion 25d. The claw main body portion 25e extends circumferentially from one circumferential end to the other circumferential end of the base portion 25d.

[0091] The claw main body 25e has an inclined surface 25h and a hooking surface 25i. The inclined surface 25h is the radially outer portion of the front surface of the claw main body 25e. The inclined surface 25h faces the front side (+Z side) and radially outward. The inclined surface 25h is located toward the rear side (-Z side) as it moves radially outward. The hooking surface 25i is the rear side surface of the claw main body 25e. The hooking surface 25i is perpendicular to the axial direction.

[0092] As shown in FIG. 21 , the claws 25c are located radially inward of the rotor body 23. The base portions 25d of the plurality of claws 25c are located radially inward of the hook portions 24k. The claw main bodies 25e of the plurality of claws 25c are located on the front side (+Z side) of the hook portions 24k. The hook surfaces 25i of the claw main bodies 25e contact the hook surfaces 24m of the hook portions 24k. The claw main bodies 25e are hooked onto the hook portions 24k from the front side. As a result, the claws 25c are hooked onto the first cover 24 from the front side. Therefore, the second cover 25 is attached to the first cover 24 by the fixing walls 25b and the claws 25c. This allows the second cover 25 to be more firmly fixed to the first cover 24, thereby further improving the rigidity of the first rotor 20. Furthermore, after hooking the claws 25c onto the first cover 24, the second cover 25 can be fixed to the first cover 24 by fixing the fixing wall 25b to the first cover 24. Therefore, the worker or the like who fixes the second cover 25 to the first cover 24 only needs to fix the first cover 24 and the second cover 25 to the fixing wall 25b using an adhesive or welding, etc. This makes it easy to fix the second cover 25 to the first cover 24.

[0093] In this specification, the term "workers, etc." includes the workers who perform each task and the equipment, etc. Each task may be performed by the worker alone, by the equipment alone, or by both the worker and the equipment.

[0094] In this embodiment, a worker or the like attaching the second cover 25 brings the second cover 25 closer to the first cover 24, which is attached to the first rotor frame 21 together with the rotor body 23, from the rear side (-Z side). As the second cover 25 approaches the first cover 24, the inclined surfaces 25h of the claws 25c come into contact with the hook portions 24k of the first cover 24 from the rear side. In this state, as the second cover 25 is brought even closer to the first cover 24, the hook portions 24k press the claws 25c radially inward, causing the base portions 25d of the claws 25c to elastically deform radially inward. As the second cover 25 is brought even closer to the first cover 24 and the claw main portions 25e are positioned closer to the front side (+Z side) than the hook portions 24k, the base portions 25d are restored and deformed radially outward, and the claw main portions 25e are hooked on the hook portions 24k from the front side. This allows the worker or the like to hook the claws 25c of the second cover 25 onto the first cover 24 from the front side by simply bringing the second cover 25 closer to the first cover 24 in the axial direction from the rear side. Note that the worker or the like may also hook the claw main body 25e onto the hook portion 24k by tilting the second cover 25 obliquely so that the claws 25c are closer to the front side than the fixed wall 25b, without elastically deforming the base 25d.

[0095] As shown in FIG. 2 , the first rotor 20 has first rotor penetration portions 28 that penetrate the first rotor 20 in the axial direction. The first rotor penetration portions 28 are arranged at intervals in the circumferential direction. In the present embodiment, twelve first rotor penetration portions 28 are provided. Each of the first rotor penetration portions 28 is provided between two first arms 22 that are adjacent in the circumferential direction. More specifically, each of the first rotor penetration portions 28 is provided between two portions of the first arms 22 that are adjacent in the circumferential direction and that are located radially inward of the second cover 25. In the present embodiment, the first rotor penetration portions 28 are fan-shaped about the central axis J in a plan view along the axial direction. A front-side (+Z-side) end of each first rotor penetration portion 28 opens radially inward of the stator 50.

[0096] A worker assembling the first rotor 20 attaches the rotor body 23 to the first rotor frame 21. The worker places the circumferential portion of the rotor body 23, which does not have the outer protrusion 23d, the first inner protrusion 23e, and the second inner protrusion 23f on the annular member 23a, from the front side (+Z side) radially between the first protrusion 22h and the second protrusion 22j of the first arm 22b. In this way, the worker places the rotor body 23 on the mounting surface 22p of each first arm 22. The worker rotates the rotor body 23 around the central axis J to insert the outer protrusion 23d of the annular member 23a into the rear side (-Z side) of the first protrusion 22h and the first inner protrusion 23e of the annular member 23a into the rear side of the second protrusion 22j. The worker inserts the pin member 26c into the second through-portion 22n from the front side and presses the pin member 26c into the first through-portion 23i and the second through-portion 22n. The worker places the first cover 24 on the front side of the rotor body 23 and secures the first cover 24 and the annular member 23a to each first arm 22a with the bolts 26b. The worker inserts the second cover 25 between the circumferentially adjacent first arms 22 from the rear side and hooks the claws 25c of the second cover 25 into the hook portions 24k of the first cover 24 from the front side. The worker fixes the fixing wall 25b of the second cover 25 to the flange portion 24f of the first cover 24 by welding or the like. The first rotor 20 is assembled in this manner. The above-described method of assembling the first rotor 20 is merely an example. The first rotor 20 may be assembled in any manner.

[0097] As shown in Fig. 4, the second rotor 30 has a second rotor frame 31, a rotor body 33, and a first cover 34. As shown in Fig. 23, the second rotor 30 has a plurality of second covers 35. A portion of the configuration of the second rotor 30 is similar to that of the first rotor 20 except that it is axially inverted. In the following description, a description of the second rotor 30 that is similar to that of the first rotor 20 except that it is axially inverted may be omitted.

[0098] The second rotor frame 31 is electrically conductive. The second rotor frame 31 is made of a non-magnetic material. In this embodiment, the second rotor frame 31 is made of metal. The metal constituting the second rotor frame 31 is, for example, aluminum. The second rotor frame 31 has a second rotor annular portion 31a and a plurality of second arms 32.

[0099] As shown in FIG. 9, the second rotor annular portion 31a is annular and surrounds the central axis J. More specifically, the second rotor annular portion 31a is substantially annular, the center of which coincides with the central axis J in a plan view along the axial direction. As shown in FIG. 24, the front end (+Z side) of the support shaft 11 is located radially inside the second rotor annular portion 31a. As shown in FIG. 9, the multiple second arms 32 extend radially outward from the second rotor annular portion 31a. The configuration of the multiple second arms 32 is similar to the configuration of the multiple first arms 22, except that they are inverted in the axial direction.

[0100] As shown in FIG. 4, the second rotor frame 31 has a propeller fixing portion 37. The propeller fixing portion 37 is provided at the front end (+Z side) of the second rotor annular portion 31a. The propeller fixing portion 37 is a portion to which the propeller 1100 is fixed. The propeller fixing portion 37 has a second top plate portion 37a, an annular protrusion 37c, and a second extension portion 37e. In other words, the second rotor frame 31 has the second top plate portion 37a, the annular protrusion 37c, and the second extension portion 37e.

[0101] The second top plate portion 37a extends radially inward from the front end (+Z side) of the second rotor annular portion 31a. The second top plate portion 37a closes a portion of the front opening of the second rotor annular portion 31a. The second top plate portion 37a is located on the front side of the support shaft 11. The second top plate portion 37a is plate-shaped with its plate surface facing the axial direction. As shown in FIG. 9 , the second top plate portion 37a is disk-shaped with its center coinciding with the central axis J in a plan view along the axial direction. The second top plate portion 37a has a plurality of holes 37b penetrating the second top plate portion 37a in the axial direction. The plurality of holes 37b are spaced apart in the circumferential direction and surround the central axis J. The plurality of holes 37b extend in the circumferential direction. The second top plate portion 37a has a central hole 37d penetrating the second top plate portion 37a in the axial direction. The central hole 37d is provided in the radial center of the second top plate portion 37a. The central hole 37d has a circular shape whose center coincides with the central axis line J in a plan view along the axial direction.

[0102] The annular protrusion 37c protrudes toward the front from the front (+Z side) surface of the second top plate portion 37a. The annular protrusion 37c is annular and surrounds the central axis J. More specifically, the annular protrusion 37c is annular and has a center that coincides with the central axis J in a plan view along the axial direction. The annular protrusion 37c is located radially outward of the central hole 37d and surrounds the central hole 37d in a plan view along the axial direction.

[0103] As shown in FIG. 24 , the second extension portion 37e extends from the second top plate portion 37a toward the rear side (−Z side) along the central axis J. In this embodiment, the second extension portion 37e is cylindrical and surrounds the central axis J, opening on both sides in the axial direction. More specifically, the second extension portion 37e is cylindrical and centered on the central axis J. The second extension portion 37e extends rearward from the periphery of the central hole 37d on the rear surface of the second top plate portion 37a. The front end (+Z side) of the second extension portion 37e opens to the front side through the central hole 37d. The outer diameter of the second extension portion 37e is smaller than the inner diameter of the conductive member 75. The rear end of the second extension portion 37e is inserted into the support shaft 11 from the front side. The rear end of the second extension portion 37e is located rearward of the third step surface 17a. The second extending portion 37e is passed through in the axial direction radially inside the conductive member 75. As a result, a portion of the second extending portion 37e is located radially inside the conductive member 75. The rear end of the second extending portion 37e is located more rearward than the rear end of the conductive member 75.

[0104] A brush 37f that contacts the inner peripheral surface of the conductive member 75 is provided on the outer peripheral surface of the second extension portion 37e. Therefore, static electricity generated in the second rotor 30 can be conducted to the conductive member 75 via the second extension portion 37e and the brush 37f, and the static electricity can be conducted from the conductive member 75 to the support shaft 11. Furthermore, as described below, the first rotor 20 is connected to the second rotor 30 via the connecting tube 40. Therefore, static electricity generated in the first rotor 20 flows to the second rotor 30 via the connecting tube 40, and similarly to the static electricity generated in the second rotor 30 described above, the static electricity generated in the first rotor 20 can be conducted to the support shaft 11. As a result, static electricity generated in the first rotor 20 and the second rotor 30 can be prevented from flowing to the first rolling bearing 71a and the second rolling bearing 71b. Therefore, electrolytic corrosion of the first rolling bearing 71a and the second rolling bearing 71b can be prevented. The brush 37f is made up of, for example, a plurality of conductive fibers that protrude radially outward from the outer circumferential surface of the second extending portion 37e.

[0105] As shown in FIG. 4, the rotor body 33 has the same configuration as the rotor body 23 of the first rotor 20, except that it is axially inverted. As shown in FIG. 6, the rotor body 33 has an annular member 33a and a magnet assembly 33b. The annular member 33a of the rotor body 33 is fixed to the second arm 32 of the second rotor frame 31, similar to the annular member 23a of the first rotor 20. As a result, the multiple magnets that make up the magnet assembly 33b of the rotor body 33 are fixed to the second rotor frame 31. The first cover 34 has the same configuration as the first cover 24 of the first rotor 20, except that it is axially inverted. The multiple second covers 35 have the same configuration as the multiple second covers 25 of the first rotor 20, except that it is axially inverted.

[0106] As shown in FIG. 1 , the second rotor 30 has second rotor through-holes 38 that penetrate the second rotor 30 in the axial direction. The second rotor through-holes 38 are arranged at intervals in the circumferential direction. In the present embodiment, twelve second rotor through-holes 38 are provided. Each of the second rotor through-holes 38 is provided between two circumferentially adjacent second arms 32. More specifically, each of the second rotor through-holes 38 is provided between two circumferentially adjacent second arms 32 that are radially inward of the second cover 35. In the present embodiment, the second rotor through-holes 38 are fan-shaped about the central axis J in a plan view along the axial direction. The rear-side (-Z side) end of each second rotor through-hole 38 opens radially inward of the stator 50.

[0107] As shown in FIG. 23, the connecting tube 40 has a tubular shape extending in the axial direction along the central axis J. More specifically, the connecting tube 40 has a substantially cylindrical shape centered on the central axis J. The connecting tube 40 extends from the second rotor annular portion 31a toward the rear side (-Z side). The second rotor annular portion 31a and the connecting tube 40 are parts of the same single member. In this embodiment, the second rotor frame 31 and the connecting tube 40 are parts of the same single member. As shown in FIG. 21, the rear side portion of the connecting tube 40 is fixed to the first rotor annular portion 21a. As a result, the connecting tube 40 connects the first rotor 20 and the second rotor 30.

[0108] 24 , the connecting tube 40 is located radially outside the support shaft 11 and surrounds the support shaft 11. In other words, the support shaft 11 is located inside the connecting tube 40. The inner circumferential surface of the connecting tube 40 is spaced radially outward from the outer circumferential surface of the support shaft 11. The connecting tube 40 has a tube main body 41, a plurality of first ribs 42, and a plurality of second ribs 43.

[0109] The tube main body portion 41 has a cylindrical shape extending from the second rotor annular portion 31a toward the rear side (-Z side). In this embodiment, the tube main body portion 41 has a cylindrical shape centered on the central axis J. The tube main body portion 41 is located radially outward of the support shaft 11. The inner circumferential surface of the tube main body portion 41 is spaced radially outward from the outer circumferential surface of the support shaft 11. The inner circumferential surface of the tube main body portion 41 is the inner circumferential surface of the connecting tube 40. A step portion 44 having a first step surface 44a facing the rear side (-Z side) is provided on a front side (+Z side) portion of the inner circumferential surface of the tube main body portion 41. The first step surface 44a is annular and surrounds the central axis J. The first step surface 44a is annular and has a center coincident with the central axis J in a plan view along the axial direction. The first step surface 44a is, for example, a surface perpendicular to the axial direction. The inner diameter of the tube main body 41 at a portion located rearward of the first stepped surface 44a is larger than the inner diameter of the tube main body 41 at a portion located frontward of the first stepped surface 44a. The rear end of the tube main body 41 is the rear end of the connecting tube 40. The rear end of the tube main body 41 is fitted into the radially inner side of the first rotor annular portion 21a. The rear end of the tube main body 41 is, for example, clearance-fitted into the radially inner side of the first rotor annular portion 21a.

[0110] A first rolling bearing 71a and a second rolling bearing 71b are located on the inner circumferential surface of the tube main body 41, i.e., radially between the inner circumferential surface of the connecting tube 40 and the outer circumferential surface of the support shaft 11. The first rolling bearing 71a and the second rolling bearing 71b rotatably support the first rotor 20 and the second rotor 30 relative to the support shaft 11. The second rolling bearing 71b is located on the front side (+Z side) of the first rolling bearing 71a, between the inner circumferential surface of the connecting tube 40 and the outer circumferential surface of the support shaft 11. The first rolling bearing 71a and the second rolling bearing 71b are annular and surround the support shaft 11. In this embodiment, the first rolling bearing 71a and the second rolling bearing 71b are ball bearings. The first rolling bearing 71a and the second rolling bearing 71b are the same rolling bearing having the same shape and size. The first rolling bearing 71a and the second rolling bearing 71b are arranged in positions opposite to each other in the axial direction. For example, angular contact ball bearings are used for the first rolling bearing 71a and the second rolling bearing 71b. The first rolling bearing 71a has an inner ring 71c, an outer ring 71d, and multiple rolling elements 71e. The second rolling bearing 71b has an inner ring 71f, an outer ring 71g, and multiple rolling elements 71h.

[0111] The inner rings 71c, 71f are annular and surround the support shaft 11. More specifically, the inner rings 71c, 71f are annular, with their centers coinciding with the central axis J when viewed in a plan view along the axial direction. The support shaft 11 is fitted inside the inner rings 71c, 71f. The inner rings 71c, 71f contact the outer peripheral surface of the support shaft 11. More specifically, at least a portion of the inner peripheral surface of each inner ring 71c, 71f contacts the outer peripheral surface of the support shaft 11. The inner rings 71c, 71f are supported so as to be movable relative to the support shaft 11 in the axial direction.

[0112] Each outer ring 71d, 71g is annular and surrounds each inner ring 71c, 71f radially outside the corresponding inner ring 71c, 71f. More specifically, each outer ring 71d, 71g is annular and its center coincides with the central axis J when viewed in a plan view along the axial direction. The outer rings 71d, 71g are fitted inside the connecting tube 40. The outer rings 71d, 71g contact the inner peripheral surface of the connecting tube 40. More specifically, at least a portion of the outer peripheral surface of each outer ring 71d, 71g contacts the inner peripheral surface of the connecting tube 40.

[0113] As shown in Figure 25, the multiple rolling elements 71e of the first rolling bearing 71a are located radially between the inner ring 71c and the outer ring 71d. The multiple rolling elements 71e are lined up in the circumferential direction. The multiple rolling elements 71h of the second rolling bearing 71b are located radially between the inner ring 71f and the outer ring 71g. The multiple rolling elements 71h are lined up in the circumferential direction. In this embodiment, the multiple rolling elements 71e and the multiple rolling elements 71h are spherical.

[0114] 24, the rear-side (-Z side) end of the inner ring 71c of the first rolling bearing 71a comes into contact with a second step surface 15a facing the front side (+Z side) and provided on the outer peripheral surface of the support shaft 11. This positions the inner ring 71c in the axial direction with respect to the support shaft 11. The front-side end of the outer ring 71g of the second rolling bearing 71b comes into contact with a first step surface 44a facing the rear side and provided on the inner peripheral surface of the connecting tube 40. This positions the outer ring 71g in the axial direction with respect to the connecting tube 40.

[0115] A first spacer 72a and a second spacer 72b are positioned axially between the first rolling bearing 71a and the second rolling bearing 71b. The first spacer 72a and the second spacer 72b are made of a non-magnetic material. The first spacer 72a and the second spacer 72b may be made of, for example, metal or resin. As shown in FIG. 25 , the first spacer 72a and the second spacer 72b are cylindrical and surround the central axis J. More specifically, the first spacer 72a and the second spacer 72b are cylindrical and centered on the central axis J. The inner diameter of the first spacer 72a is larger than the outer diameter of the second spacer 72b. The first spacer 72a is positioned radially outward of the second spacer 72b and spaced apart from it. The first spacer 72a surrounds the second spacer 72b. As shown in FIG. 24, the first spacer 72a and the second spacer 72b are positioned radially outward of the support shaft 11 and surround the support shaft 11. As shown in FIG.

[0116] The first spacer 72a is located axially between the outer ring 71d of the first rolling bearing 71a and the outer ring 71g of the second rolling bearing 71b. The first spacer 72a contacts the outer ring 71d of the first rolling bearing 71a and the outer ring 71g of the second rolling bearing 71b. The second spacer 72b is located axially between the inner ring 71c of the first rolling bearing 71a and the inner ring 71f of the second rolling bearing 71b. The second spacer 72b contacts the inner ring 71c of the first rolling bearing 71a and the inner ring 71f of the second rolling bearing 71b.

[0117] The first spacer 72a is fitted into the connecting tube 40. The outer peripheral surface of the first spacer 72a contacts the inner peripheral surface of the connecting tube 40. The support shaft 11 is fitted inside the second spacer 72b. The inner peripheral surface of the second spacer 72b contacts the outer peripheral surface of the support shaft 11. The second spacer 72b is elastically deformable in the axial direction. When subjected to the same compressive stress in the axial direction, the amount of axial compression due to elastic deformation of the second spacer 72b is greater than the amount of compression of the first spacer 72a.

[0118] The first spacer 72a has a spacer main body 72c, a first annular protrusion 72d, and a second annular protrusion 72e. The spacer main body 72c is cylindrical and surrounds the central axis J. More specifically, the spacer main body 72c is cylindrical and centered on the central axis J. The first annular protrusion 72d protrudes radially inward from a rear-side (-Z side) end of the inner circumferential surface of the spacer main body 72c. The second annular protrusion 72e protrudes radially inward from a front-side (+Z side) end of the inner circumferential surface of the spacer main body 72c. The first annular protrusion 72d and the second annular protrusion 72e are annular and surround the central axis J. More specifically, the first annular protrusion 72d and the second annular protrusion 72e are annular and surround the central axis J. More specifically, the first annular protrusion 72d and the second annular protrusion 72e are annular and surround the central axis J. The first annular protrusion 72d contacts the front end of the outer ring 71d of the first rolling bearing 71a, and the second annular protrusion 72e contacts the rear end of the outer ring 71g of the second rolling bearing 71b.

[0119] The radial thickness between the inner and outer circumferential surfaces of the second spacer 72b is smaller than the radial thickness between the inner and outer circumferential surfaces of the first spacer 72a. The radial thickness between the inner and outer circumferential surfaces of the first spacer 72a includes the radial thickness between the inner and outer circumferential surfaces of the first annular protrusion 72d and the outer circumferential surface of the spacer main body 72c, the radial thickness between the inner and outer circumferential surfaces of the spacer main body 72c, and the radial thickness between the inner and outer circumferential surface of the second annular protrusion 72e and the outer circumferential surface of the spacer main body 72c.

[0120] A bearing support member 73 is located on the rear side (-Z side) of the first rolling bearing 71a. As shown in FIG. 25 , the bearing support member 73 is annular and surrounds the central axis J. The bearing support member 73 is annular and has a center coincident with the central axis J in a plan view along the axial direction. The bearing support member 73 has a plurality of second recesses 73b recessed radially outward from the inner peripheral surface of the bearing support member 73. The plurality of second recesses 73b are arranged at intervals in the circumferential direction. The plurality of second recesses 73b are arranged at equal intervals around one circumference in the circumferential direction. In this embodiment, the interior of the second recesses 73b is open to both axial sides. The interior of the second recesses 73b is rectangular in a plan view along the axial direction. In this embodiment, four second recesses 73b are provided. The bearing support member 73 has a third thread portion 73a on its outer peripheral surface.

[0121] As shown in FIG. 24 , the bearing support member 73 is located radially inward of the connecting tube 40 and radially outward of the support shaft 11. The bearing support member 73 surrounds the support shaft 11. The inner circumferential surface of the bearing support member 73 is located radially outwardly away from the outer circumferential surface of the support shaft 11. The bearing support member 73 is located on the rear side (-Z side) of the outer ring 71d of the first rolling bearing 71a. The bearing support member 73 contacts the rear end of the outer ring 71d of the first rolling bearing 71a. The bearing support member 73 sandwiches the outer ring 71d of the first rolling bearing 71a, the first spacer 72a, and the outer ring 71g of the second rolling bearing 71b between itself and a first stepped surface 44a provided on the inner circumferential surface of the connecting tube 40 in the axial direction. The first spacer 72a maintains the axial distance between the outer ring 71d of the first rolling bearing 71a and the outer ring 71g of the second rolling bearing 71b. A third threaded portion 73a provided on the outer peripheral surface of the bearing support member 73 meshes with a fourth threaded portion 41a provided on the inner peripheral surface of the tube main body 41. In other words, the connecting tube 40 has a fourth threaded portion 41a that meshes with the third threaded portion 73a on a portion of its inner peripheral surface that is located more rearward than the outer ring 71d of the first rolling bearing 71a. Therefore, by rotating the bearing support member 73, the axial position of the bearing support member 73 relative to the connecting tube 40 can be adjusted, and the axial distance between the bearing support member 73 and the first step surface 44a can be adjusted. This allows the outer ring 71d of the first rolling bearing 71a, the first spacer 72a, and the outer ring 71g of the second rolling bearing 71b to be sandwiched between the bearing support member 73 and the first step surface 44a without any gaps being created between the components, thereby making it possible to stably maintain the axial distance between the outer ring 71d of the first rolling bearing 71a and the outer ring 71g of the second rolling bearing 71b.

[0122] In this embodiment, as described above, the bearing support member 73 has a plurality of second recesses 73b that are recessed radially outward from the inner circumferential surface of the bearing support member 73 and spaced apart in the circumferential direction. Therefore, by inserting part of a tool into at least one of the plurality of second recesses 73b, an operator can easily use the tool to rotate the bearing support member 73 about the central axis J. This makes it easy to adjust the axial position of the bearing support member 73.

[0123] A preload member 74 is located on the front side (+Z side) of the second rolling bearing 71b. The preload member 74 is located on the front side of the inner ring 71f of the second rolling bearing 71b. The preload member 74 contacts the front end of the inner ring 71f of the second rolling bearing 71b. The preload member 74 is attached to the support shaft 11. The attachment structure for attaching the preload member 74 to the support shaft 11 is an attachment structure that makes it possible to adjust the axial position of the preload member 74 relative to the support shaft 11. Therefore, by moving the preload member 74 axially relative to the support shaft 11, it is possible to change the axial distance between the preload member 74 and the second step surface 15a provided on the outer circumferential surface of the support shaft 11. The inner ring 71c of the first rolling bearing 71a, the second spacer 72b, and the inner ring 71f of the second rolling bearing 71b are located axially between the preload member 74 and the second stepped surface 15a. Therefore, when the axial distance between the preload member 74 and the second stepped surface 15a becomes smaller than the sum of the axial dimensions of each component, the second spacer 72b undergoes compressive elastic deformation in the axial direction. This reduces the axial distance between the inner ring 71c of the first rolling bearing 71a and the inner ring 71f of the second rolling bearing 71b. When the distance between the inner ring 71c of the first rolling bearing 71a and the inner ring 71f of the second rolling bearing 71b decreases while the distance between the outer ring 71d of the first rolling bearing 71a and the outer ring 71g of the second rolling bearing 71b is maintained by the first spacer 72a, the inner ring of each rolling bearing shifts axially relative to the outer ring. This applies a preload to each rolling bearing. The preload applied to each rolling bearing increases as the axial distance between the inner ring 71c of the first rolling bearing 71a and the inner ring 71f of the second rolling bearing 71b decreases. Therefore, an operator can adjust the preload applied to the first rolling bearing 71a and the second rolling bearing 71b by adjusting the axial position of the preload member 74 relative to the support shaft 11. This allows the worker or the like to apply a desired preload to the first rolling bearing 71a and the second rolling bearing 71b, thereby improving the rigidity of the first rolling bearing 71a and the rigidity of the second rolling bearing 71b.Therefore, in the first rolling bearing 71a and the second rolling bearing 71b, the outer rings can be prevented from tilting relative to the inner rings, and the connecting tube 40, with which the outer rings of the rolling bearings come into contact, can be prevented from tilting relative to the support shaft 11. Because the connecting tube 40 connects the first rotor 20 and the second rotor 30, tilting of the connecting tube 40 relative to the support shaft 11 can be prevented, thereby preventing tilting of the first rotor 20 and the second rotor 30 relative to the support shaft 11. In particular, because the second rotor annular portion 31a of the second rotor 30 and the connecting tube 40 are part of the same single member, tilting of the connecting tube 40 relative to the support shaft 11 can be prevented, which further prevents tilting of the second rotor 30 relative to the support shaft 11. As described above, tilting of the first rotor 20 and the second rotor 30 can be prevented.

[0124] When the motor 100 is mounted on the propulsion device 1000, the force generated by the propeller 1100 varies in the circumferential direction, and this tends to generate a force on the first rotor 20 and the second rotor 30 that tilts the first rotor 20 and the second rotor 30. In contrast, according to the present embodiment, the first rotor 20 and the second rotor 30 can be prevented from tilting as described above. In this way, the effect of preventing the first rotor 20 and the second rotor 30 from tilting is particularly useful when the motor 100 is mounted on the propulsion device 1000. Furthermore, the propeller 1100 is attached to the second rotor 30. As described above, the second rotor 30 is prevented from tilting more than the first rotor 20, and therefore, even if a non-uniform force is applied to the second rotor 30 in the circumferential direction due to the rotation of the propeller 1100, tilting of the second rotor 30 can be suitably prevented.

[0125] In this embodiment, as described above, the radial thickness between the inner and outer circumferential surfaces of the second spacer 72b is smaller than the radial thickness between the inner and outer circumferential surfaces of the first spacer 72a. Therefore, it is easy to reduce the radial thickness between the inner and outer circumferential surfaces of the second spacer 72b, and the second spacer 72b can be easily elastically deformed in the axial direction. This makes it easy to compress and elastically deform the second spacer 72b in the axial direction when the preload member 74 is moved axially relative to the support shaft 11. This makes it easy to adjust the preload applied to the first rolling bearing 71a and the second rolling bearing 71b. Furthermore, it is easy to increase the radial thickness between the inner and outer circumferential surfaces of the first spacer 72a, and the first spacer 72a can easily maintain a stable axial distance between the outer ring 71d of the first rolling bearing 71a and the outer ring 71g of the second rolling bearing 71b.

[0126] As described above, in this embodiment, the first spacer 72a has the first annular protrusion 72d and the second annular protrusion 72e that protrude radially inward from the inner circumferential surface of the spacer main body 72c. This improves the rigidity of the first spacer 72a. Therefore, the first spacer 72a more stably maintains the axial distance between the outer ring 71d of the first rolling bearing 71a and the outer ring 71g of the second rolling bearing 71b. Furthermore, because the first annular protrusion 72d protrudes radially inward from the rear-side (-Z side) end of the inner circumferential surface of the spacer main body 72c, the first annular protrusion 72d increases the radial thickness between the inner circumferential surface and the outer circumferential surface of the first spacer 72a at the rear-side end. This increases the contact area between the first spacer 72a and the outer ring 71d of the first rolling bearing 71a. Because the second annular protrusion 72e protrudes radially inward from the front-side (-Z side) end of the inner circumferential surface of the spacer main body 72c, the second annular protrusion 72e increases the radial thickness between the inner circumferential surface and the outer circumferential surface at the front-side end of the first spacer 72a. This increases the contact area between the first spacer 72a and the outer ring 71g of the second rolling bearing 71b. Therefore, the first spacer 72a can more stably support the outer ring 71d of the first rolling bearing 71a and the outer ring 71g of the second rolling bearing 71b.

[0127] In this embodiment, as described above, the rear end (-Z side) of the tube main body portion 41, i.e., the rear end of the connecting tube 40, is fitted to the radially inner side of the first rotor annular portion 21a. Therefore, the connecting tube 40 and the first rotor frame 21 can be positioned with good axial accuracy with respect to the central axis J. Also, tilting of the first rotor frame 21 relative to the connecting tube 40 can be suppressed. Therefore, tilting of the first rotor 20 can be further suppressed.

[0128] As shown in FIG. 26, the preload member 74 is annular and surrounds the central axis J. More specifically, the preload member 74 is annular and has a center coincident with the central axis J when viewed in a plan view along the axial direction. The preload member 74 surrounds the front end (+Z side) of the support shaft 11. The outer diameter of the preload member 74 is smaller than the outer diameters of the first rolling bearing 71a and the second rolling bearing 71b. As shown in FIG. 24, the preload member 74 is provided radially inward and spaced apart from the inner circumferential surface of the second rotor annular portion 31a. The preload member 74 has a nut portion 74a and a contact portion 74b.

[0129] The nut portion 74a is annular and surrounds the support shaft 11. In this embodiment, the nut portion 74a is annular and has a center coincident with the central axis J in a plan view along the axial direction. The nut portion 74a has, on its inner circumferential surface, a second threaded portion 74d that meshes with the first threaded portion 16. In other words, in this embodiment, the mounting structure for mounting the preload member 74 to the support shaft 11 is a structure in which the first threaded portion 16 meshes with the second threaded portion 74d. Therefore, by rotating the nut portion 74a, an operator can move the preload member 74 in the axial direction relative to the support shaft 11, and can adjust the axial position of the preload member 74 relative to the support shaft 11. Therefore, by rotating the nut portion 74a, an operator can easily adjust the preload applied to the first rolling bearing 71a and the second rolling bearing 71b. The mounting structure for mounting the preload member 74 to the support shaft 11 is not particularly limited as long as it is a mounting structure that allows the axial position of the preload member 74 relative to the support shaft 11 to be adjusted, and may be a structure other than a screw.

[0130] As shown in FIG. 26 , the nut portion 74a has multiple first recesses 74c recessed radially inward from the outer circumferential surface of the nut portion 74a. The multiple first recesses 74c are spaced apart circumferentially. Therefore, by inserting part of a tool into at least one of the multiple first recesses 74c, an operator can easily rotate the nut portion 74a around the central axis J using the tool. This allows the operator to easily adjust the axial position of the preload member 74. Therefore, the operator can more easily adjust the preload applied to the first rolling bearing 71a and the second rolling bearing 71b. The multiple first recesses 74c are arranged at equal intervals around the circumferential circumference. In this embodiment, twelve first recesses 74c are provided. The interior of each first recess 74c opens to both axial ends. A radially inner portion of the inner surface of each first recess 74c has an arc shape recessed radially inward in a plan view along the axial direction.

[0131] As shown in FIG. 24, the contact portion 74b protrudes rearward from the rear-side (-Z side) surface of the nut portion 74a. The contact portion 74b is annular and surrounds the central axis J. More specifically, the contact portion 74b is annular and has a center coincident with the central axis J in a plan view along the axial direction. The inner circumferential surface of the contact portion 74b is located radially outward from the inner circumferential surface of the nut portion 74a. The outer circumferential surface of the contact portion 74b is located radially inward from the outer circumferential surface of the nut portion 74a. The rear-side end of the contact portion 74b contacts the front-side (+Z side) end of the inner ring 71f of the second rolling bearing 71b. As shown in FIG. 26, in this embodiment, the multiple first recesses 74c are provided across the contact portion 74b.

[0132] As shown in FIG. 24 , the multiple first ribs 42 protrude radially outward from the outer peripheral surface of the tube main body portion 41. The multiple first ribs 42 are arranged at intervals in the circumferential direction. The multiple first ribs 42 are arranged at equal intervals around the circumference. The number of first ribs 42 is the same as the number of first protruding walls 21b. That is, in this embodiment, six first ribs 42 are provided. The front-side (+Z side) surfaces of the multiple first ribs 42 are inclined surfaces that are positioned toward the rear-side (-Z side) as they extend radially outward. The rear-side surfaces of the multiple first ribs 42 are perpendicular to the axial direction. The rear-side surfaces of the multiple first ribs 42 contact the front-side surface of the first rotor annular portion 21a. This positions the first rotor frame 21 in the axial direction relative to the connecting tube 40.

[0133] As shown in FIG. 21 , each of the first ribs 42 has a threaded hole 42b axially penetrating the first rib 42. The threaded holes 42b of the first ribs 42 are located on the front side (+Z side) of a corresponding one of the holes 21c provided in the first rotor annular portion 21a. A bolt 26a is threaded through each of the holes 21c from the rear side (-Z side) and is fastened to each of the threaded holes 42b from the rear side. This secures the first ribs 42 to the first rotor annular portion 21a. Therefore, the rigidity of the connecting tube 40 can be improved by the first ribs 42, and the connecting tube 40 can be firmly secured to the first rotor frame 21 via the first ribs 42. This further prevents the first rotor 20 from tilting. A washer 26h is provided between the head of the bolt 26a and the rear surface of the first rotor annular portion 21a. The washer 26h is, for example, a wave washer.

[0134] As shown in FIG. 23 , each of the multiple first ribs 42 has an opposing surface 42a facing radially outward. The opposing surfaces 42a of the multiple first ribs 42 extend circumferentially in a plan view along the axial direction. As shown in FIG. 21 , the opposing surfaces 42a of the multiple first ribs 42 are disposed facing radially inward of the radially inner surfaces 21d of the respective first protruding walls 21b. At least one opposing surface 42a contacts the radially inner surface 21d of the first protruding wall 21b. This allows the connecting tube 40 and the first rotor frame 21 to be positioned with high axial accuracy relative to the central axis J. Furthermore, tilting of the first rotor frame 21 relative to the connecting tube 40 can be further suppressed. Therefore, tilting of the first rotor 20 can be further suppressed. In this embodiment, the opposing surfaces 42a of the multiple first ribs 42 disposed around the central axis J are fitted to the radially inner surfaces of the multiple first protruding walls 21b disposed around the central axis J.

[0135] As shown in FIG. 23 , the multiple second ribs 43 protrude radially outward from the outer peripheral surface of the tube main body 41. The multiple second ribs 43 are arranged at intervals in the circumferential direction. The multiple second ribs 43 are connected to the rear side (-Z side) surfaces of the multiple second arms 32, respectively. Therefore, the multiple second ribs 43 can further improve the rigidity of the connecting tube 40. Also, the connection strength between the connecting tube 40 and the second rotor frame 31 can be improved. The second rotor frame 31 can be further prevented from tilting relative to the connecting tube 40. Therefore, the second rotor 30 can be further prevented from tilting.

[0136] As shown in FIGS. 27 and 28 , the stator 50 is annular and surrounds the central axis J. More specifically, the stator 50 is annular, the center of which coincides with the central axis J in a plan view along the axial direction. As shown in FIG. 6 , the stator 50 is located axially between the first rotor 20 and the second rotor 30. The stator 50 is located on the front side (+Z side) of the first rotor 20 and on the rear side (-Z side) of the second rotor 30. The stator 50 has an inner housing 51, an outer housing 52, a plurality of electromagnet portions 53, a stator cover 58, and a resin portion 80.

[0137] As shown in FIGS. 27 and 28, the electromagnet portions 53 are arranged around the central axis. The electromagnet portions 53 are arranged at equal intervals around the circumference. In this embodiment, 24 electromagnet portions 53 are provided. As shown in FIG. 29, each of the electromagnet portions 53 has a stator core 53a and a coil 53b. The stator core 53a is made of a magnetic material. As shown in FIG. 30, the stator core 53a has a first core portion 53c, a second core portion 53d, and a third core portion 53e.

[0138] The first core portion 53c extends in the axial direction. Although not shown, the first core portion 53c is composed of a plurality of plate members stacked in the radial direction. The plurality of plate members constituting the first core portion 53c are, for example, electromagnetic steel sheets. The first core portion 53c has a core main body portion 53i and connecting portions 53j and 53k. The core main body portion 53i extends in the axial direction. As shown in FIG. 29 , the core main body portion 53i has a generally trapezoidal shape whose circumferential dimension decreases radially inward when viewed in a plan view along the axial direction.

[0139] As shown in FIG. 30, the connecting portion 53j is connected to the front-side (+Z side) end of the core body portion 53i. The connecting portion 53k is connected to the rear-side (-Z side) end of the core body portion 53i. As shown in FIG. 27, the connecting portion 53j has a rectangular shape extending in the radial direction when viewed in a plan view along the axial direction. The circumferential dimension of the connecting portion 53j is smaller than the circumferential dimension of the core body portion 53i. The connecting portion 53j is the front-side end of the first core portion 53c. As shown in FIG. 28, the connecting portion 53k has a rectangular shape extending in the radial direction when viewed in a plan view along the axial direction. The circumferential dimension of the connecting portion 53k is smaller than the circumferential dimension of the core body portion 53i. The connecting portion 53k is the rear-side end of the first core portion 53c.

[0140] 27, the second core portion 53d is annular and surrounds the front end (+Z side) of the first core portion 53c, i.e., the connecting portion 53j. The outer peripheral surface of the second core portion 53d has a generally trapezoidal shape with rounded corners that decreases in circumferential dimension toward the radially inner side in a plan view along the axial direction. The radially inner portion of the outer peripheral surface of the second core portion 53d has an arc shape that convex radially inward in a plan view along the axial direction.

[0141] The inner peripheral surface of the second core portion 53d has the same shape as the outer peripheral surface of the connecting portion 53j in a plan view along the axial direction. That is, in this embodiment, the inner peripheral surface of the second core portion 53d has a rectangular shape extending in the radial direction in a plan view along the axial direction. The connecting portion 53j is fitted inside the second core portion 53d. The inner peripheral surface of the second core portion 53d contacts the outer peripheral surface of the connecting portion 53j, i.e., the outer peripheral surface of the first core portion 53c. The inner peripheral surface of the second core portion 53d contacts the outer peripheral surface of the connecting portion 53j over the entire circumference of the second core portion 53d surrounding the first core portion 53c. As shown in FIG. 30, the second core portion 53d is located on the front side (+Z side) of the coil 53b. The material constituting the second core portion 53d is, for example, a soft magnetic composite (SMC).

[0142] 28, the third core portion 53e has an annular shape surrounding the rear-side (-Z side) end of the first core portion 53c, i.e., the connecting portion 53k. The outer peripheral surface of the third core portion 53e has a generally trapezoidal shape with rounded corners that decreases in circumferential dimension toward the radially inner side in a plan view along the axial direction. The radially inner portion of the outer peripheral surface of the third core portion 53e has an arc shape that convex radially inward in a plan view along the axial direction.

[0143] The inner peripheral surface of the third core portion 53e has the same shape as the outer peripheral surface of the connecting portion 53k in a plan view along the axial direction. That is, in this embodiment, the inner peripheral surface of the third core portion 53e has a rectangular shape extending in the radial direction in a plan view along the axial direction. The connecting portion 53k is fitted inside the third core portion 53e. The inner peripheral surface of the third core portion 53e contacts the outer peripheral surface of the connecting portion 53k, i.e., the outer peripheral surface of the first core portion 53c. The inner peripheral surface of the third core portion 53e contacts the outer peripheral surface of the connecting portion 53k over the entire circumference of the third core portion 53e surrounding the first core portion 53c. As shown in FIG. 30, the third core portion 53e is located on the rear side (-Z side) of the coil 53b. The material constituting the third core portion 53e is, for example, a soft magnetic composite material. In this embodiment, the third core portion 53e is a member having the same size and shape as the second core portion 53d.

[0144] As shown in FIG. 29, the coil 53b is annular in a plan view along the axial direction. The coil 53b surrounds the stator core 53a. In this embodiment, the coil 53b is located radially outside the core body portion 53i in the first core portion 53c and surrounds the core body portion 53i. Although not shown, the coil 53b is formed of a conductor wound around the stator core 53a. The conductor forming the coil 53b is, for example, a rectangular wire. The conductor forming the coil 53b may also be a round wire.

[0145] Each of the electromagnet sections 53 functions as a magnet when a current flows through the coil 53b. As shown in FIG. 30, each of the electromagnet sections 53 has a magnetic pole 53f and a magnetic pole 53g. That is, the stator 50 has a plurality of magnetic poles 53f and a plurality of magnetic poles 53g. Each of the magnetic poles 53f, 53g functions as a magnetic pole of a magnet when a current flows through the coil 53b of the electromagnet section 53. When a current flows through the coil 53b of the electromagnet section 53, one of the magnetic poles 53f and 53g becomes an N pole, and the other becomes an S pole. The magnetic poles 53f and 53g are switched between an N pole and an S pole when the direction of the current flowing through the coil 53b is reversed.

[0146] Each magnetic pole 53f is an end portion on the rear side (-Z side) of each stator core 53a. Each magnetic pole 53g is an end portion on the front side (+Z side) of each stator core 53a. That is, each stator core 53a has a magnetic pole 53f and a magnetic pole 53g. The magnetic pole 53f is formed by the rear end portion of the first core portion 53c, i.e., the connecting portion 53k, and the third core portion 53e. The magnetic pole 53g is formed by the front end portion of the first core portion 53c, i.e., the connecting portion 53j, and the second core portion 53d. As shown in FIG. 6, the multiple magnetic poles 53f face the front end face of the first rotor 20. The multiple magnetic poles 53g face the rear end face of the second rotor 30. In this embodiment, the front end face of the first rotor 20 is the front end face of the first cover 24, and is the front surface of the first top plate portion 24c of the first cover 24. In this embodiment, the rear end face of the second rotor 30 is the rear end face of the first cover 34, and is the rear surface of the first top plate portion 34c of the first cover 34.

[0147] As shown in FIG. 31 , the inner housing 51 is annular and surrounds the central axis J. In this embodiment, the inner housing 51 is annular, with its center coinciding with the central axis J in a plan view along the axial direction. In this embodiment, the inner housing 51 is made of a non-magnetic metal. The metal constituting the inner housing 51 is, for example, aluminum. As shown in FIG. 29 , the inner housing 51 is positioned radially inward of the multiple electromagnet portions 53. The inner housing 51 has an inner housing annular portion 51 a, multiple inner fins 51 b, and multiple first housing protrusions 51 c.

[0148] As shown in FIG. 31 , the inner housing annular portion 51a is annular and surrounds the central axis J. In this embodiment, the inner housing annular portion 51a is annular and has a center coincident with the central axis J in a plan view along the axial direction. As shown in FIG. 32 , the inner housing annular portion 51a has a first annular portion 51e and a second annular portion 51f. The first annular portion 51e is a front-side (+Z side) portion of the inner housing annular portion 51a. The first annular portion 51e has a first groove 51d on the front side that is recessed toward the rear side (-Z side). The first groove 51d is annular and surrounds the central axis J. In other words, the inner housing 51 has a first groove 51d on the front side that is recessed toward the rear side and surrounds the central axis J. The first groove 51d is annular and has a center coincident with the central axis J in a plan view along the axial direction. The surface of the inner surface of the first groove 51d that is positioned radially outward is an inner contact surface 51i. That is, the inner housing 51 has an inner contact surface 51i. The inner contact surface 51i extends in the circumferential direction and faces radially inward. In this embodiment, the inner contact surface 51i has an annular shape whose center coincides with the central axis J in a plan view along the axial direction.

[0149] The portion of the first annular portion 51e located radially inside the first groove 51d is the inner portion 51k. The portion of the first annular portion 51e located radially outside the first groove 51d is the outer portion 51m. The inner circumferential surface of the inner portion 51k is the inner circumferential surface of the first annular portion 51e and constitutes a part of the inner circumferential surface of the inner housing annular portion 51a. The outer circumferential surface of the inner portion 51k includes the surface of the inner surface of the first groove 51d that is located radially inside. The outer circumferential surface of the outer portion 51m is the outer circumferential surface of the first annular portion 51e and constitutes a part of the outer circumferential surface of the inner housing annular portion 51a. The inner circumferential surface of the outer portion 51m is the inner contact surface 51i. The front side (+Z side) end of the inner portion 51k is located closer to the front than the front side end of the outer portion 51m. The radial thickness between the inner and outer peripheral surfaces of the inner portion 51k is greater than the radial thickness between the inner and outer peripheral surfaces of the outer portion 51m.

[0150] The second annular portion 51f is the rear side (-Z side) portion of the inner housing annular portion 51a. The second annular portion 51f is connected to the rear end of the first annular portion 51e. More specifically, the second annular portion 51f is connected to the rear end of the outer portion 51m. The inner diameter of the second annular portion 51f is larger than the inner diameter of the first annular portion 51e. The inner circumferential surface of the second annular portion 51f is located radially outward from the inner circumferential surface of the first annular portion 51e. The inner circumferential surface of the second annular portion 51f constitutes a part of the inner circumferential surface of the inner housing annular portion 51a. The outer circumferential surface of the second annular portion 51f constitutes a part of the outer circumferential surface of the inner housing annular portion 51a. The outer circumferential surface of the second annular portion 51f is located at the same position in the radial direction as the outer circumferential surface of the outer portion 51m. The outer circumferential surface of the second annular portion 51f is connected without a step to the rear side of the outer circumferential surface of the outer portion 51m.

[0151] A stepped surface 51g facing the rear side is provided between the first annular portion 51e and the second annular portion 51f in the axial direction. That is, the inner housing annular portion 51a has, on its inner circumferential surface, a stepped surface 51g facing the rear side. The stepped surface 51g is annular and surrounds the central axis J. More specifically, the stepped surface 51g is annular, with its center coinciding with the central axis J in a plan view along the axial direction. The stepped surface 51g is a rear-side (-Z side) surface of a portion of the first annular portion 51e that is positioned radially inward of the second annular portion 51f. The stepped surface 51g is perpendicular to the axial direction. A seal groove 51h recessed toward the front side (+Z side) is provided in the stepped surface 51g. The seal groove 51h is annular, with its center coinciding with the central axis J in a plan view along the axial direction.

[0152] As shown in FIG. 29 , the inner housing annular portion 51a has an inner housing recess 51n recessed radially outward from the inner circumferential surface of the inner housing annular portion 51a. In this embodiment, the inner housing recess 51n recesses radially outward from the inner circumferential surface of the second annular portion 51f. Although not shown, in this embodiment, the inner housing recess 51n is a groove extending in the axial direction. The inner housing recess 51n opens to the rear side (−Z side). The inner surface of the inner housing recess 51n has a semicircular arc shape recessed radially outward in a plan view along the axial direction. The inner housing recess 51n is provided on the inner circumferential surface of the inner housing annular portion 51a in a circumferential portion where the first housing protrusion 51c is provided on the outer circumferential surface. The circumferential center of the inner housing recess 51n is located at the same position in the circumferential direction as the circumferential center of one of the first housing protrusions 51c.

[0153] As shown in FIG. 32, the multiple inner fins 51b protrude radially inward from the inner circumferential surface of the inner housing annular portion 51a. In this embodiment, the multiple inner fins 51b protrude radially inward from the inner circumferential surface of the first annular portion 51e, i.e., the inner circumferential surface of the inner portion 51k. The multiple inner fins 51b protrude radially inward from a portion of the inner circumferential surface of the inner housing annular portion 51a that is located closer to the front (+Z side) than the stepped surface 51g. The multiple inner fins 51b are plate-shaped with their plate surfaces facing the circumferential direction. The multiple inner fins 51b are rectangular and elongated in the radial direction when viewed along the circumferential direction. The axial dimension of the multiple inner fins 51b is the same as the axial dimension of the inner portion 51k. The multiple inner fins 51b are arranged at equal intervals in the circumferential direction. As shown in FIG. 31, the multiple inner fins 51b are arranged at equal intervals throughout the entire circumferential direction of the inner circumferential surface of the inner housing annular portion 51a. The distance between the circumferentially adjacent inner fins 51b is smaller than the radial dimension of the inner fins 51b.

[0154] As shown in FIG. 3 , the multiple inner fins 51b have portions that are radially aligned with the first rotor penetration portions 28 and the second rotor penetration portions 38. The first rotor penetration portions 28 and the second rotor penetration portions 38 have portions that overlap with at least one inner fin 51b in a planar view along the axial direction. In this embodiment, the first rotor penetration portions 28 and the second rotor penetration portions 38 overlap with the multiple inner fins 51b in a planar view along the axial direction. The inner fins 51b that axially overlap with the first rotor penetration portions 28 and the second rotor penetration portions 38 sequentially change to other inner fins 51b as the first rotor 20 and the second rotor 30 rotate. Regardless of the rotational position of the first rotor 20 and the second rotor 30, each first rotor penetration portion 28 and each second rotor penetration portion 38 overlaps with at least one inner fin 51b in the axial direction. Regardless of the rotational positions of the first rotor 20 and the second rotor 30, one or more of the multiple inner fins 51b are exposed to the rear side (-Z side) of the motor 100 through the first rotor penetration portion 28. Regardless of the rotational positions of the first rotor 20 and the second rotor 30, one or more of the multiple inner fins 51b are exposed to the front side (+Z side) of the motor 100 through the second rotor penetration portion 38.

[0155] As shown in FIG. 32, the first housing protrusions 51c protrude radially outward from the outer peripheral surface of the inner housing annular portion 51a. In this embodiment, the first housing protrusions 51c are provided across the outer peripheral surface of the first annular portion 51e, i.e., the outer peripheral surface of the outer portion 51m, and the outer peripheral surface of the second annular portion 51f. The first housing protrusions 51c extend in the axial direction from the front-side (+Z side) end of the outer peripheral surface of the outer portion 51m to the rear-side (-Z side) end of the outer peripheral surface of the second annular portion 51f. The first housing protrusions 51c are spaced apart in the circumferential direction. As shown in FIG. 31, the first housing protrusions 51c are spaced apart in the circumferential direction around one circumference. The number of first housing protrusions 51c is the same as the number of electromagnet portions 53. That is, in this embodiment, 24 first housing protrusions 51c are provided.

[0156] As shown in FIG. 29, the circumferential dimensions of the multiple first housing protrusions 51c decrease radially outward. Each of the first housing protrusions 51c has a generally triangular shape that protrudes radially outward in a plan view along the axial direction. The circumferential side surfaces of the first housing protrusions 51c are curved surfaces that recess radially inward in a plan view along the axial direction. At least a portion of each of the first housing protrusions 51c is located circumferentially between the radially inner ends of the circumferentially adjacent coils 53b. In this embodiment, the radially outer portions of each of the first housing protrusions 51c are located circumferentially between the radially inner ends of the circumferentially adjacent coils 53b.

[0157] As shown in FIG. 31 , the outer housing 52 is annular and surrounds the central axis J. In this embodiment, the outer housing 52 is annular and has a center coincident with the central axis J in a plan view along the axial direction. The outer housing 52 is located radially outward from the inner housing 51. The outer housing 52 surrounds the inner housing 51. In this embodiment, the outer housing 52 is made of a non-magnetic metal. The metal constituting the outer housing 52 is, for example, aluminum. As shown in FIG. 29 , the outer housing 52 is located radially outward from the multiple electromagnet portions 53. The outer housing 52 surrounds the multiple electromagnet portions 53. As shown in FIGS. 1 to 3 , the outer housing 52 is located radially outward from the radial outer edges of the first rotor 20 and the second rotor 30. In other words, the stator 50 has the outer housing 52 as a portion located radially outward from the first rotor 20 and the second rotor 30. As shown in FIG. 31, the outer housing 52 has an outer housing annular portion 52a, a plurality of outer fins 52b, a plurality of second housing protruding portions 52c, a fourth protruding wall 52d, and a plurality of housing fixed portions 52f.

[0158] The outer housing annular portion 52a is annular and surrounds the central axis J. In this embodiment, the outer housing annular portion 52a is annular in shape, with its center coinciding with the central axis J in a plan view along the axial direction. As shown in FIG. 27 , the outer housing annular portion 52a surrounds a plurality of electromagnet portions 53. In a plan view along the axial direction, the radially outer edge of the outer housing annular portion 52a has a plurality of outer housing recesses 52e recessed radially inward and spaced apart in the circumferential direction. The plurality of outer housing recesses 52e are arranged at equal intervals around the circumference. In this embodiment, six outer housing recesses 52e are provided. A housing fixed portion 52f is provided at the rear end (-Z side) of each outer housing recess 52e.

[0159] The multiple outer fins 52b protrude radially outward from the outer peripheral surface of the outer housing annular portion 52a. In this embodiment, the multiple outer fins 52b protrude radially outward from portions of the outer peripheral surface of the outer housing annular portion 52a that are circumferentially positioned differently from the portions where the outer housing recesses 52e and the housing fixed portions 52f are provided. The multiple outer fins 52b are not arranged in the portions of the outer peripheral surface of the outer housing annular portion 52a where the outer housing recesses 52e and the housing fixed portions 52f are provided. The multiple outer fins 52b are plate-shaped with their plate surfaces facing the circumferential direction. The multiple outer fins 52b are rectangular in shape with their long axial lengths when viewed circumferentially.

[0160] As shown in FIG. 30, the axial dimension of the multiple outer fins 52b is larger than the axial dimension of the outer housing annular portion 52a. The front-side (+Z side) ends of the multiple outer fins 52b are located closer to the front than the front-side end of the outer housing annular portion 52a. In other words, the multiple outer fins 52b protrude further forward than the outer housing annular portion 52a. The rear-side (-Z side) ends of the multiple outer fins 52b are located at the same axial position as the rear-side end of the outer housing annular portion 52a. A notch 52t is provided at the radially outer end of the rear-side end of each outer fin 52b. As shown in FIG. 31, the multiple outer fins 52b are arranged at intervals in the circumferential direction. The multiple outer fins 52b are arranged at equal intervals along the circumferential direction in each portion of the outer housing annular portion 52a between circumferentially adjacent outer housing recesses 52e. The distance between the circumferentially adjacent outer fins 52b is smaller than the radial dimension of the outer fins 52b.

[0161] 6, the radially outer ends of the outer fins 52b are located radially outward from the radially outer edges of the first rotor 20 and the second rotor 30. In other words, the radially outer edges of the first rotor 20 and the second rotor 30 are located radially inward from the radially outer ends of the multiple outer fins 52b. In the present embodiment, the entire outer fin 52b is located radially outward from the radially outer edges of the first rotor 20 and the second rotor 30.

[0162] In this embodiment, the stator 50 is provided with multiple inner fins 51b and multiple outer fins 52b, thereby improving the heat dissipation of the stator 50. Specifically, the first rotor penetration portion 28 and the second rotor penetration portion 38 have portions that overlap with at least one inner fin 51b in a plan view along the axial direction. This makes it easier for air passing through the first rotor penetration portion 28 and the second rotor penetration portion 38 to come into contact with at least one inner fin 51b. This makes it easier for heat from the stator 50 to be released into the air from the multiple inner fins 51b. This improves the heat dissipation of the stator 50. In this way, in the axial-flux motor 100, by providing each rotor with a rotor penetration portion and opening each rotor penetration portion to a space radially inward of the stator 50, air can easily flow radially inward of the stator 50 through each rotor penetration portion. This improves the heat dissipation of the stator 50. Furthermore, in this embodiment, the radially outer edges of the first rotor 20 and the second rotor 30 are located radially inward relative to the radially outer ends of the multiple outer fins 52b. This prevents the multiple outer fins 52b from being covered from both axial sides by the first rotor 20 and the second rotor 30, making it easier for air flowing axially relative to the motor 100 to come into contact with the multiple outer fins 52b. This makes it easier for heat from the stator 50 to be released into the air from the multiple outer fins 52b. This further improves the heat dissipation performance of the stator 50.

[0163] In this embodiment, the rotation of the first rotor 20 and the second rotor 30, which in turn rotates the propeller 1100, generates an airflow from the front side (+Z side) to the rear side (-Z side). Part of the air passes through the second rotor penetration portion 38, comes into contact with the multiple inner fins 51b, and flows through the first rotor penetration portion 28 to the rear side of the motor 100. Another part of the air flows to the rear side on the radial outside of the second rotor 30, comes into contact with the multiple outer fins 52b, and flows through the radial outside of the first rotor 20 to the rear side of the motor 100.

[0164] As shown in FIG. 33, the multiple second housing protrusions 52c protrude radially inward from the inner circumferential surface of the outer housing annular portion 52a. The multiple second housing protrusions 52c extend in the axial direction. The multiple second housing protrusions 52c are spaced apart in the circumferential direction. As shown in FIG. 31, the multiple second housing protrusions 52c are provided in a portion of the inner circumferential surface of the outer housing annular portion 52a different from the portion where the housing through holes 52m (described later) are provided. The multiple second housing protrusions 52c are each provided at a position facing the radially outer side of the first housing protrusion 51c. The number of second housing protrusions 52c is less than the number of first housing protrusions 51c by the number of housing through holes 52m. Three housing through holes 52m are provided. In other words, in this embodiment, 21 second housing protrusions 52c are provided.

[0165] As shown in FIG. 29, the circumferential dimensions of the multiple second housing protrusions 52c decrease radially inward. Each second housing protrusion 52c has a generally triangular shape that protrudes radially inward in a plan view along the axial direction. The circumferential side surface of each second housing protrusion 52c is a curved surface that recesses radially outward in a plan view along the axial direction. At least a portion of each second housing protrusion 52c is located circumferentially between the radially outer ends of circumferentially adjacent coils 53b. In this embodiment, the radially inner portion of each second housing protrusion 52c is located circumferentially between the radially outer ends of circumferentially adjacent coils 53b.

[0166] As shown in FIG. 33 , the fourth protruding wall 52d is a protruding wall that protrudes frontward from the radially inner edge of the front-side (+Z side) surface of the outer housing annular portion 52a. The fourth protruding wall 52d extends in the circumferential direction. The fourth protruding wall 52d is located radially inward of and spaced apart from portions of the outer fins 52b that protrude further frontward than the outer housing annular portion 52a. In other words, the portions of the outer fins 52b that are located further frontward than the outer housing annular portion 52a are located radially outward from the fourth protruding wall 52d. The front-side end of the fourth protruding wall 52d is located closer to the rear (-Z side) than the front-side end of the outer fins 52b. The radially outer surface of the fourth protruding wall 52d is the outer contact surface 52j. In other words, the outer housing 52 has the outer contact surface 52j. The outer contact surface 52j faces radially outward. The outer contact surface 52j extends in the circumferential direction.

[0167] 31, a plurality of fourth protruding walls 52d are provided at intervals in the circumferential direction. Each fourth protruding wall 52d is provided at an end on the front side (+Z side) of a portion of the outer housing annular portion 52a that is located between two outer housing recesses 52e adjacent to each other in the circumferential direction. In this embodiment, six fourth protruding walls 52d are provided.

[0168] The multiple housing fixed portions 52f protrude radially outward from the outer peripheral surface of the outer housing annular portion 52a. In this embodiment, the multiple housing fixed portions 52f protrude radially outward from each of the multiple outer housing recesses 52e. More specifically, the multiple housing fixed portions 52f protrude radially outward from the rear-side (-Z side) end of each of the multiple outer housing recesses 52e. The multiple housing fixed portions 52f are arranged at intervals in the circumferential direction. The multiple housing fixed portions 52f are arranged at equal intervals around one circumference.

[0169] As shown in Figure 34, the housing fixed portion 52f has a main body portion 52h and a protrusion portion 52i. The main body portion 52h has a substantially rectangular parallelepiped shape. The main body portion 52h has a hole 52g that penetrates the main body portion 52h in the axial direction. The protrusion portion 52i protrudes radially outward from the front side (+Z side) of the main body portion 52h. The protrusion portion 52i has a substantially rectangular parallelepiped shape.

[0170] The multiple housing fixed portions 52f are located on the front side (+Z side) of the support pillars 14 of the multiple stator support portions 12. Each support pillar 14 of the multiple stator support portions 12 contacts the rear side (-Z side) surface of the housing fixed portion 52f. As a result, each support pillar 14 of the multiple stator support portions 12 contacts, from the rear side, a portion of the stator 50 that is located radially outward from the first rotor 20. Therefore, the multiple stator support portions 12 can stably support the stator 50, which is axially sandwiched between the first rotor 20 and the second rotor 30. This prevents the stator 50 from tilting with respect to the central axis J. Furthermore, because gaps are provided between circumferentially adjacent stator support portions 12, the multiple stator support portions 12 do not cover the entire rear side surface of the first rotor 20. This makes it possible to prevent the air flowing through the first rotor penetrating portion 28 from being blocked by the plurality of stator support portions 12, and to prevent the heat dissipation performance of the motor 100 from decreasing.

[0171] In this embodiment, the rear side (-Z side) surface of the main body portion 52h contacts the front side (+Z side) surface of the support pillar main body portion 14a. The rear side end of the main body portion 52h is located radially inside the wall portion 14b. The radially outer surface of the main body portion 52h contacts the radially inner surface of the wall portion 14b. The radially outer surface of the main body portion 52h may face the radially inner surface of the wall portion 14b via a gap. The protrusion portion 52i is located on the front side of the wall portion 14b. A gap is provided axially between the protrusion portion 52i and the wall portion 14b. Note that the protrusion portion 52i and the wall portion 14b may contact each other.

[0172] As shown in FIG. 6 , a bolt 55 is inserted through the hole 52g from the front side (+Z side). The bolt 55 inserted through the hole 52g is screwed into a threaded hole 14c provided on the front surface of the support column main body 14a. This allows each support column 14 to be fixed to each housing fixed portion 52f with the bolt 55. Therefore, the stator 50 can be fixed to multiple stator support portions 12, thereby more stably supporting the stator 50. Furthermore, since the stator 50 can be fixed to each stator support portion 12 with the bolt 55, the stator 50 can be firmly fixed to the multiple stator support portions 12. Furthermore, because the multiple housing fixed portions 52f are spaced apart in the circumferential direction, multiple outer fins 52b can be provided on portions of the outer peripheral surface of the outer housing annular portion 52a where no housing fixed portions 52f are provided. This allows the multiple outer fins 52b to dissipate heat from the stator 50 to the air that comes into contact with the multiple outer fins 52b. Therefore, the heat dissipation performance of the stator 50 can be further improved.

[0173] As shown in FIG. 31 , the outer housing 52 has a housing through-hole 52m that penetrates from the inner peripheral surface to the outer peripheral surface of the outer housing 52. The housing through-hole 52m penetrates a rear-side (-Z side) portion of the outer housing annular portion 52a in the radial direction from the inner peripheral surface to the outer peripheral surface. In this embodiment, the housing through-hole 52m is circular when viewed in the radial direction. A plurality of housing through-holes 52m are provided at intervals in the circumferential direction. In this embodiment, three housing through-holes 52m are provided. The plurality of outer fins 52b include outer fins 52s provided on the outer peripheral surface of the circumferential portion of the outer housing annular portion 52a where the housing through-hole 52m is provided. The outer fin 52s has an end that is more rearward than the outer fins 52b provided in other circumferential portions and is located closer to the front (+Z side). The rear end of the outer fin 52s is located closer to the front than the housing through-hole 52m. A plurality of outer fins 52s are provided for each housing through-hole 52m.

[0174] As shown in FIG. 30 , the front end (+Z side) of the inner housing 51 and the front end of the outer housing 52 are located at the same position in the axial direction. The front end of the inner housing 51 is the front end of the inner housing annular portion 51a and the front end of the first annular portion 51e. The front end of the outer housing 52 is the front end of the multiple outer fins 52b. The rear end (-Z side) of the inner housing 51 is located closer to the front than the rear end of the outer housing 52. The rear end of the inner housing 51 is located closer to the front than the rear end of the coil 53b. The rear end of the inner housing 51 is the rear end of the inner housing annular portion 51a and the rear end of the second annular portion 51f. The rear end of the outer housing 52 is the rear end of the outer housing annular portion 52a and the rear end of the multiple outer fins 52b.

[0175] As shown in FIG. 29 , multiple electromagnet portions 53 are disposed radially between the inner housing 51 and the outer housing 52. A portion of a resin portion 80 is filled in the radial space between the inner housing 51 and the outer housing 52. Each coil 53b in the multiple electromagnet portions 53 is embedded in the resin portion 80. Therefore, heat generated in each coil 53b can be transferred to the inner housing 51 and the outer housing 52 via the resin portion 80. The heat transferred to the inner housing 51 is released from the multiple inner fins 51b to the air outside the motor 100. The heat transferred to the outer housing 52 is released from the multiple outer fins 52b to the air outside the motor 100. Therefore, the heat dissipation performance of the stator 50 can be further improved.

[0176] As shown in FIG. 30 , the resin part 80 has a first resin part 81 and a second resin part 82. The first resin part 81 is a front-side (+Z side) part of the resin part 80. The first resin part 81 is a part filled radially between the inner housing 51 and the outer housing 52. The first resin part 81 is annular and surrounds the central axis J. The second resin part 82 is a rear-side (-Z side) part of the resin part 80. The second resin part 82 is connected to the rear side of the first resin part 81. The second resin part 82 is annular and surrounds the central axis J. An inner circumferential surface of the second resin part 82 is located radially inward of the inner circumferential surface of the first resin part 81. The part of the second resin part 82 located radially inward of the first resin part 81 covers a rear-side surface of a bus bar holder 61 (described later) and a rear-side end of the inner housing annular part 51 a. The inner circumferential surface of the second resin part 82 is located at the same radial position as the inner circumferential surface of the bus bar holder 61, which will be described later. The rear-side surface of the second resin part 82 forms part of the rear-side surface of the stator 50. The magnetic poles 53f of the multiple electromagnet parts 53 are exposed on the rear-side surface of the second resin part 82.

[0177] The resin part 80 is formed by attaching a jig to an assembly in which the stator 50 and the busbar assembly 60 are assembled together with all the other components except the resin part 80, and pouring resin into the space surrounded by the jig, the inner housing 51, the outer housing 52, and the stator cover 58. The resin that forms the resin part 80 is, for example, an epoxy resin.

[0178] As described above, in this embodiment, at least a portion of each first housing protrusion 51c is located circumferentially between the radially inner ends of circumferentially adjacent coils 53b. Therefore, each first housing protrusion 51c, which is part of the inner housing 51, can be disposed close to each coil 53b. This shortens the shortest distance between the coil 53b and the inner housing 51, making it easier to transfer heat from the coil 53b to the inner housing 51 via the resin portion 80. Furthermore, at least a portion of each second housing protrusion 52c is located circumferentially between the radially outer ends of circumferentially adjacent coils 53b. Therefore, each second housing protrusion 52c, which is part of the outer housing 52, can be disposed close to each coil 53b. This shortens the shortest distance between the coil 53b and the outer housing 52, making it easier to transfer heat from the coil 53b to the outer housing 52 via the resin portion 80. This allows the heat of coil 53b to be more easily transferred to inner housing 51 and outer housing 52, thereby further improving the heat dissipation performance of stator 50.

[0179] In this embodiment, as described above, the circumferential dimensions of the multiple first housing protrusions 51c decrease radially outward. The circumferential dimensions of the multiple second housing protrusions 52c decrease radially inward. This makes it easier to align the shapes of the multiple first housing protrusions 51c and the multiple second housing protrusions 52c with the shape of the annular coil 53b in a plan view along the axial direction. This makes it easier to bring the circumferential side surfaces of the housing protrusions closer to the coils 53b while preventing the housing protrusions from contacting the coils 53b. This further improves the heat dissipation of the stator 50.

[0180] As shown in FIG. 27 , the stator cover 58 is annular and surrounds the central axis J. In this embodiment, the stator cover 58 is annular, with its center coinciding with the central axis J in a plan view along the axial direction. The stator cover 58 is fixed to the front end (+Z side) of the inner housing 51 and the front end of the outer housing 52. The stator cover 58 blocks a portion of the radial space between the front end of the inner housing 51 and the front end of the outer housing 52. The material constituting the stator cover 58 is non-magnetic and non-conductive. In this embodiment, the stator cover 58 is made of resin. The resin constituting the stator cover 58 has excellent thermal conductivity. Examples of resins constituting the stator cover 58 include resins mixed with graphite or ceramic.

[0181] As shown in FIG. 35 , the stator cover 58 has a cover main body portion 58a, an inner annular wall 58b, and an outer annular wall 58c. The cover main body portion 58a is annular and surrounds the central axis J. More specifically, the cover main body portion 58a is annular and has a center that coincides with the central axis J in a plan view along the axial direction. The cover main body portion 58a is plate-shaped with its plate surface facing the axial direction. The cover main body portion 58a has a plurality of cover through holes 58f that penetrate the cover main body portion 58a in the axial direction. The plurality of cover through holes 58f are arranged at intervals in the circumferential direction. The plurality of cover through holes 58f are arranged at equal intervals around one circumference in the circumferential direction.

[0182] As shown in FIG. 27 , each second core portion 53d of the multiple electromagnet portions 53 is disposed inside each cover through hole 58f. Each second core portion 53d is fitted into each cover through hole 58f. The inner edge of each cover through hole 58f has the same shape as the outer edge of each second core portion 53d in a plan view along the axial direction. In this embodiment, the inner edge of each cover through hole 58f contacts the outer edge of each second core portion 53d over the entire circumference. This allows heat generated in the coil 53b to be transferred from the second core portion 53d to the stator cover 58. The heat transferred to the stator cover 58 is transferred to the inner housing 51 or the outer housing 52 and then released into the air outside the motor 100 through the inner fins 51b or the outer fins 52b. This further improves the heat dissipation performance of the stator 50. In this embodiment, the stator cover 58 is made of a resin with excellent thermal conductivity, which makes it easier to transfer heat from the second core portion 53d to the stator cover 58. Therefore, the heat dissipation performance of the stator 50 can be further improved.

[0183] As shown in FIG. 35, the cover main body portion 58a has a second groove 58d recessed toward the front side (+Z side) and extending circumferentially at the radially outer edge of the rear-side (-Z side) surface. In this embodiment, a plurality of second grooves 58d are provided at intervals in the circumferential direction. The number of second grooves 58d is the same as the number of fourth protruding walls 52d. That is, in this embodiment, six second grooves 58d are provided. As shown in FIG. 30, the front-side end of the fourth protruding wall 52d is fitted into the second groove 58d. The radially inner surface of the fourth protruding wall 52d contacts the radially inner surface of the second groove 58d. The radially outer surface of the fourth protruding wall 52d contacts the radially outer surface of the inner surface of the second groove 58d. The front-side end face of the fourth protruding wall 52d contacts the front-side surface of the inner surface of the second groove 58d. The front end of the fourth protruding wall 52d may face the front side of the inner surface of the second groove 58d via a gap.

[0184] As shown in FIG. 35, the inner annular wall 58b protrudes from the inner peripheral edge of the cover main body portion 58a toward the rear side (-Z side). The inner annular wall 58b is annular and surrounds the central axis J. In this embodiment, the inner annular wall 58b is cylindrical and centered on the central axis J. As shown in FIG. 30, the inner annular wall 58b is fitted into the first groove 51d. The outer peripheral surface of the inner annular wall 58b contacts the inner contact surface 51i, which is the surface of the inner surface of the first groove 51d that is located radially outward. The inner peripheral surface of the inner annular wall 58b contacts the surface of the inner surface of the first groove 51d that is located radially inward.

[0185] As shown in FIG. 35, the outer annular wall 58c protrudes toward the rear side (-Z side) from the outer peripheral edge of the cover main body portion 58a. The outer annular wall 58c is annular and surrounds the central axis J. In this embodiment, the outer annular wall 58c is cylindrical and centered on the central axis J. As shown in FIG. 30, a portion of the outer annular wall 58c is located radially between the multiple outer fins 52b and the fourth protruding wall 52d. The inner peripheral surface of the outer annular wall 58c contacts the outer contact surface 52j, which is the radially outer surface of the fourth protruding wall 52d. The outer peripheral surface of the outer annular wall 58c contacts the radially inner edges of the multiple outer fins 52b at portions that protrude further toward the front side (+Z side) than the outer housing annular portion 52a. The rear-side end of the outer annular wall 58c contacts the radially outer edge of the front-side end face of the outer housing annular portion 52a. The rear end of the outer annular wall 58c may face the radially outer edge of the front end face of the outer housing annular portion 52a with a gap therebetween.

[0186] As described above, in this embodiment, the stator cover 58 partially covers the radial space between the front end (+Z side) of the inner housing 51 and the front end of the outer housing 52. The stator cover 58 has an annular inner annular wall 58b and an annular outer annular wall 58c. The outer peripheral surface of the inner annular wall 58b contacts the inner contact surface 51i, and the inner peripheral surface of the outer annular wall 58c contacts the outer contact surface 52j. Therefore, when the resin portion 80 is formed by potting, in which resin is poured into the radial space between the inner housing 51 and the outer housing 52, leakage of the poured resin from between the inner housing 51 and the stator cover 58 and between the outer housing 52 and the stator cover 58 is suppressed. Furthermore, because the stator cover 58 is made of resin, the shape of the cover through-hole 58f can be easily formed to match the shape of the second core portion 53d. Furthermore, even if the shape of the cover through hole 58f is slightly different from the shape of the second core portion 53d, it is easy to deform the stator cover 58 to match the shape of the cover through hole 58f to the shape of the second core portion 53d. This makes it easy to accurately bring the inner edge of the cover through hole 58f into contact with the outer edge of the second core portion 53d. Therefore, when molding the resin portion 80, leakage of resin from between the inner edge of the cover through hole 58f and the outer edge of the second core portion 53d can be prevented. As a result, the stator cover 58 can prevent resin from leaking when molding the resin portion 80. Therefore, adhesion of resin to unintended locations on the stator 50 can be prevented when molding the resin portion 80. Furthermore, since the outer peripheral surface of the inner annular wall 58b contacts the inner contact surface 51i and the inner peripheral surface of the outer annular wall 58c contacts the outer contact surface 52j, the stator cover 58 can be accurately positioned radially relative to the inner housing 51 and the outer housing 52. Furthermore, the stator cover 58 is provided with a cover through-hole 58f in which the second core portion 53d is disposed. Therefore, the stator cover 58 can be positioned with high radial accuracy relative to the inner housing 51 and the outer housing 52, and the electromagnet portion 53 having the second core portion 53d can be positioned with high radial accuracy relative to the inner housing 51 and the outer housing 52. Furthermore, in this embodiment, the stator cover 58 is made of resin.Therefore, compared to when the stator cover 58 is made of ceramics, for example, the linear expansion coefficient of the stator cover 58 is likely to be close to the linear expansion coefficient of the metal inner housing 51 and outer housing 52. As a result, even if the inner housing 51, outer housing 52, and stator cover 58 expand due to heat, the difference between the amount of deformation of the inner housing 51 and outer housing 52 and the amount of deformation of the stator cover 58 is likely to be small. Furthermore, because resin is more easily deformed than ceramics, even if there is a difference between the amount of deformation of the inner housing 51 and outer housing 52 and the amount of deformation of the stator cover 58, resin is likely to deform in accordance with the amount of deformation of the inner housing 51 and outer housing 52. Therefore, even if the inner housing 51, outer housing 52, and stator cover 58 expand due to heat, damage to the stator cover 58 is suppressed.

[0187] As described above, in this embodiment, the surface of the inner surface of the first groove 51d provided in the inner housing 51 that is located radially outward is the inner contact surface 51i. The inner annular wall 58b is fitted into the first groove 51d. This makes it easier to position the stator cover 58 radially relative to the inner housing 51 with greater precision. Furthermore, the provision of the first groove 51d makes it easier to increase the contact area between the inner annular wall 58b and the inner housing 51. This makes it possible to further prevent resin from leaking between the inner annular wall 58b and the inner housing 51 when molding the resin portion 80.

[0188] As described above, in this embodiment, a portion of the outer annular wall 58c is located radially between the multiple outer fins 52b and the fourth protruding wall 52d. Therefore, the multiple outer fins 52b can be used to prevent the outer annular wall 58c from shifting radially outward relative to the outer housing 52. This allows the stator cover 58 to be positioned radially relative to the outer housing 52 with greater precision.

[0189] As described above, in this embodiment, the front end (+Z side) of the fourth protruding wall 52d is fitted into the second groove 58d provided in the cover main body portion 58a, thereby enabling the stator cover 58 to be positioned radially relative to the outer housing 52 with greater precision.

[0190] As shown in FIG. 35 , in a plan view along the axial direction, the radially outer edge of the stator cover 58 has a plurality of stator cover recesses 58e recessed radially inward and spaced apart in the circumferential direction. In this embodiment, the plurality of stator cover recesses 58e are provided across the radially outer edge of the cover main body portion 58a and the outer annular wall 58c. As shown in FIG. 34 , the plurality of stator cover recesses 58e overlap with the plurality of outer housing recesses 52e in a plan view along the axial direction. The provision of the outer housing recesses 52e and the stator cover recesses 58e prevents the head of the bolt 55 from contacting the outer peripheral surface of the outer housing annular portion 52a and the radially outer edge of the stator cover 58 when the bolt 55 is inserted into the hole 52g from the front side (+Z side). Furthermore, the radial position of the bolt 55 can be positioned radially inward compared to a case where the outer housing recesses 52e and the stator cover recesses 58e are not provided. This prevents the head of the bolt 55, the housing fixed portion 52f fixed to the stator support portion 12 by the bolt 55, and the stator support portion 12 from protruding radially outward beyond the outer fins 52b, thereby preventing the motor 100 from becoming larger in size in the radial direction.

[0191] 36, in at least one electromagnet portion 53, a wiring member 57 is connected to the coil 53b. The wiring member 57 is drawn out to the outside of the outer housing 52 through the housing through-hole 52m. Therefore, compared to when the wiring member 57 is drawn, for example, radially inward of the inner housing 51, it is possible to prevent the wiring member 57 from coming into contact with the first rotor 20 and the second rotor 30. Furthermore, it is possible to easily connect the wiring member 57 to an external power source (not shown). This makes it easier to pass a current through the coil 53b via the wiring member 57.

[0192] The wiring member 57 has a wiring main body 57a and a connector portion 57b. The wiring main body 57a is a wiring that is drawn out radially outward from the outer housing 52 and connected to an external power source (not shown). The connector portion 57b is connected to one end of the wiring main body 57a. The connector portion 57b is fixed within the housing through-hole 52m. The connector portion 57b has a connector cover 57c and a connection terminal 57d.

[0193] The connector cover 57c has a cylindrical shape that extends radially. The inner peripheral surface of the connector cover 57c is circular when viewed radially. The connector cover 57c opens radially inward and radially outward. The connector cover 57c has an inserted portion 57e, a tapered portion 57f, and a retaining portion 57g. The inserted portion 57e is inserted into the housing through-hole 52m. The outer diameter of the inserted portion 57e is smaller than the inner diameter of the housing through-hole 52m.

[0194] The tapered portion 57f is connected to the radially outer end of the inserted portion 57e. The tapered portion 57f is located radially outward of the outer housing annular portion 52a. The outer diameter of the tapered portion 57f decreases radially outward. The outer diameter of the tapered portion 57f at its radially inner end is larger than the outer diameter of the inserted portion 57e and the inner diameter of the housing through-hole 52m. The radially inner end of the tapered portion 57f faces the circumferential edge of the housing through-hole 52m on the outer peripheral surface of the outer housing annular portion 52a. The outer diameter of the radially outer end of the tapered portion 57f is smaller than, for example, the inner diameter of the housing through-hole 52m.

[0195] The retaining portion 57g is connected to the radially inner end of the inserted portion 57e. The retaining portion 57g is located radially inside the outer housing annular portion 52a. The outer diameter of the retaining portion 57g is larger than the outer diameter of the inserted portion 57e, the outer diameter of the tapered portion 57f, and the inner diameter of the housing through-hole 52m. The retaining portion 57g faces the periphery of the housing through-hole 52m on the inner circumferential surface of the outer housing annular portion 52a.

[0196] The connection terminal 57d is located inside the connector cover 57c. The connection terminal 57d is made of metal. The connection terminal 57d has, for example, a cylindrical shape with openings on both radial sides. One end of the wire main body 57a is electrically connected to the connection terminal 57d.

[0197] The operator inserts and pushes the radially outer end of the tapered portion 57f into the housing through-hole 52m from the radially inner side of the outer housing annular portion 52a, thereby elastically deforming the tapered portion 57f and passing through the housing through-hole 52m. Once the tapered portion 57f passes through the housing through-hole 52m and is positioned radially outward of the outer housing annular portion 52a, it restores its original shape. This allows the tapered portion 57f to hook onto the periphery of the housing through-hole 52m from the radially outer side, preventing the connector portion 57b from coming off the housing through-hole 52m toward the radially inner side of the outer housing annular portion 52a. The retaining portion 57g hooks onto the periphery of the housing through-hole 52m from the radially inner side. This prevents the connector portion 57b from coming off the housing through-hole 52m toward the radially outer side of the outer housing annular portion 52a. In this manner, the connector portion 57b is fixed to the housing through-hole 52m.

[0198] One end of the conductor 53p constituting the coil 53b is connected to the connector portion 57b. Since the wiring member 57 has the connector portion 57b fixed in the housing through-hole 52m in this manner, the conductor 53p constituting the coil 53b can be easily connected to the wiring member 57. One end of the conductor 53p is inserted into the connector cover 57c from the radially inner end of the connector cover 57c and electrically connected to the connection terminal 57d. For example, the one end of the conductor 53p is press-fitted into the cylindrical connection terminal 57d. For example, after the one end of the conductor 53p is inserted into the connection terminal 57d, the connection terminal 57d may be crushed together with the retaining portion 57g, thereby crimping the one end of the conductor 53p to the connection terminal 57d.

[0199] 2, a plurality of wiring members 57 are provided at intervals in the circumferential direction. The plurality of wiring members 57 are arranged at equal intervals around the circumference. In this embodiment, three wiring members 57 are provided. That is, in this embodiment, one wiring member 57 is connected to the coil 53b of each of three of the plurality of electromagnet portions 53.

[0200] As shown in FIG. 29 , the busbar assembly 60 is located radially inside the stator 50. The busbar assembly 60 is annular and surrounds the central axis J. In this embodiment, the busbar assembly 60 is annular and has a center that coincides with the central axis J when viewed in a plan view along the axial direction. As shown in FIG. 37 , the busbar assembly 60 includes a busbar holder 61 and a busbar 62.

[0201] The busbar holder 61 is annular and surrounds the central axis J. In this embodiment, the busbar holder 61 is annular, with its center coinciding with the central axis J in a plan view along the axial direction. A portion of the busbar 62 is embedded and fixed in the busbar holder 61. The busbar holder 61 is made of resin. The busbar holder 61 is made, for example, by insert molding using the busbar 62 as an insert member.

[0202] As shown in FIG. 30 , the busbar holder 61 is disposed radially inside the stator 50 and at a position overlapping with some of the multiple inner fins 51b in a plan view along the axial direction. Other parts of the multiple inner fins 51b are disposed at a different position from the busbar holder 61 in a plan view along the axial direction. Because the busbar holder 61 overlaps with some of the multiple inner fins 51b in the axial direction, air flowing axially inside the radial direction of the stator 50 can come into contact with the multiple inner fins 51b and the busbar holder 61. This facilitates dissipation of heat generated in the busbar 62 from the surface of the busbar holder 61 to the air. Furthermore, other parts of the multiple inner fins 51b are disposed at a position not overlapping with the busbar holder 61 in the axial direction. Therefore, the multiple inner fins 51b are not entirely covered by the busbar holder 61 in the axial direction, which prevents air from flowing between the multiple inner fins 51b in the circumferential direction. This prevents a decrease in the heat dissipation performance of the stator 50 via the multiple inner fins 51b. Therefore, the heat dissipation performance of the busbars 62 can be improved while suppressing a decrease in the heat dissipation performance of the stator 50. This improves the heat dissipation performance of the motor 100. Furthermore, because the busbar holders 61 are disposed radially inside the stator 50, the motor 100 is prevented from becoming larger in size in the radial direction compared to when the busbar holders 61 are disposed radially outside the stator 50. Furthermore, because it is not necessary to dispose the busbar holders 61 radially outside the stator 50, it is easy to maximize the radial size of the stator 50, the first rotor 20, and the second rotor 30 within the limited arrangement space of the motor 100. This improves the efficiency of the motor 100.

[0203] In a conventional configuration in which rotors are disposed on both axial sides of the stator, as in the present embodiment, the stator is sandwiched between two rotors in the axial direction, which has the problem of heat buildup in the stator and reduced heat dissipation performance of the motor. Furthermore, because the stator is sandwiched between two rotors in the axial direction, it has been difficult to arrange a bus bar holder. To address these problems, in the present embodiment, as described above, the bus bar holder 61 is arranged radially inside the stator 50, and the bus bar holder 61 axially overlaps with some of the multiple inner fins 51b, thereby improving the heat dissipation performance of the motor 100. Furthermore, by arranging the bus bar holder 61 radially inside the stator 50, the bus bar holder 61 can be arranged while preventing the motor 100 from becoming larger in the radial direction. Thus, the effects of improving the heat dissipation performance of the motor 100 and arranging the bus bar holder 61 while preventing the motor 100 from becoming larger in size are particularly useful in a configuration in which rotors are disposed on both axial sides of the stator 50.

[0204] In this embodiment, the bus bar holder 61 is located on the rear side (-Z side) of the multiple inner fins 51b. In other words, the multiple inner fins 51b are located on the front side (+Z side) of the bus bar holder 61. The bus bar holder 61 is fitted to the radially inner side of the inner housing annular portion 51a. In this embodiment, the bus bar holder 61 is fitted to the radially inner side of the second annular portion 51f. That is, the bus bar holder 61 is fitted to the radially inner side of a portion of the inner housing annular portion 51a that is located on the rear side of the stepped surface 51g. The outer peripheral surface of the bus bar holder 61 contacts the inner peripheral surface of the second annular portion 51f. The front side (+Z side) surface of the bus bar holder 61 contacts the stepped surface 51g. More specifically, a radially outer portion of the front side surface of the bus bar holder 61 contacts the stepped surface 51g.

[0205] An annular first seal member 54 is disposed between the front-side (+Z-side) surface of the busbar holder 61 and the step surface 51g, surrounding the central axis J. Therefore, even if resin seeps into the gap between the outer peripheral surface of the busbar holder 61 and the inner peripheral surface of the second annular portion 51f when molding the resin portion 80, the first seal member 54 can prevent the resin from reaching the radially inner end between the front-side surface of the busbar holder 61 and the step surface 51g. This can prevent the resin from leaking radially inward from between the busbar holder 61 and the step surface 51g when molding the resin portion 80. Therefore, leakage of the resin can be further prevented when molding the resin portion 80. Furthermore, by preventing the resin from leaking radially inward from between the busbar holder 61 and the step surface 51g, adhesion of the resin to the inner fins 51b can be prevented. This can prevent the spaces between the inner fins 51b from being partially filled with resin. Therefore, the surface area of ​​the plurality of inner fins 51b that comes into contact with the air can be prevented from becoming smaller, and the heat dissipation performance of the stator 50 can be further prevented from decreasing.

[0206] A radially inner portion of the busbar holder 61 is located radially inward of the stepped surface 51g. In a plan view along the axial direction, the busbar holder 61 overlaps with portions of the inner fins 51b, including their radially outer ends. In this embodiment, the busbar holder 61 overlaps with radially outer portions of each inner fin 51b in a plan view along the axial direction. The inner circumferential surface of the busbar holder 61 is located radially outward of the radially inner ends of the inner fins 51b. In other words, the radially inner ends of the inner fins 51b are located radially inward of the inner circumferential surface of the busbar holder 61. Therefore, the outer circumferential surface of the busbar holder 61 is supported from the radially outer side by the inner housing annular portion 51a, while some of the inner fins 51b can be positioned so as not to overlap with the busbar holder 61 in the axial direction. The inner circumferential surface of the busbar holder 61 is located at the same radial position as the inner circumferential surface of the second resin portion 82. The rear side (-Z side) surface of the bus bar holder 61 comes into contact with the front side (+Z side) surface of the second resin portion 82 at a portion located radially inward from the first resin portion 81.

[0207] The radial thickness between the inner and outer peripheral surfaces of the busbar holder 61 is equal to or smaller than the radial dimension of the inner fins 51b. In this embodiment, the radial thickness between the inner and outer peripheral surfaces of the busbar holder 61 is smaller than the radial dimension of the inner fins 51b. The axial dimension H3 of the busbar holder 61 is smaller than the axial dimension H1 of the stator 50. Therefore, the entire busbar holder 61 can be disposed radially inside the stator 50. Furthermore, because the busbar holder 61 can be made smaller in the axial direction, heat from the busbars 62 embedded in the busbar holder 61 can be more easily transferred to the axial end faces of the busbar holder 61. This makes it easier for heat from the busbars 62 to be released into the air that comes into contact with the axial end faces of the busbar holder 61. Therefore, the heat dissipation performance of the motor 100 can be further improved.

[0208] The axial dimension H3 of the bus bar holder 61 is equal to or smaller than the axial dimension H2 of the multiple inner fins 51b. Therefore, within the range of the axial dimension H1 of the stator 50, the bus bar holder 61 can be made smaller in the axial direction, and the multiple inner fins 51b can be made larger in the axial direction. This makes it easier to dissipate heat from the bus bar 62 from the bus bar holder 61 into the air, and also increases the surface area of ​​the multiple inner fins 51b. This further improves the heat dissipation of the bus bar 62 and the stator 50, thereby further improving the heat dissipation of the motor 100.

[0209] In this embodiment, the axial dimension H3 of the busbar holder 61 is smaller than the axial dimension H2 of the multiple inner fins 51b. The axial dimension H3 of the busbar holder 61 is equal to or smaller than the axial dimension H4 of the second resin portion 82. In this embodiment, the axial dimension H3 of the busbar holder 61 is the same as the axial dimension H4 of the second resin portion 82. In this embodiment, the axial dimension H3 of the busbar holder 61 is the same as the axial dimension of the second annular portion 51f. The rear end (-Z side) of the busbar holder 61 is located at the same axial position as the rear end of the second annular portion 51f, i.e., the rear end of the inner housing 51.

[0210] As shown in FIG. 29 , the bus bar holder 61 has a holder main body 61a and a protrusion 61b. The holder main body 61a is annular and surrounds the central axis J. More specifically, the holder main body 61a is annular, with its center coinciding with the central axis J in a plan view along the axial direction. The holder main body 61a is a portion into which a bus bar 62 is partially embedded. The protrusion 61b protrudes radially outward from the outer circumferential surface of the holder main body 61a. The protrusion 61b is located inside an inner housing recess 51n provided on the inner circumferential surface of the inner housing annular portion 51a. This allows the protrusion 61b to be circumferentially engaged with the inner surface of the inner housing recess 51n. This allows the bus bar holder 61 to be circumferentially positioned relative to the inner housing 51.

[0211] In this embodiment, the protrusion 61b has a semicircular shape that protrudes radially outward in a plan view along the axial direction. The protrusion 61b is fitted into the inner housing recess 51n. Although not shown, the protrusion 61b extends in the axial direction. For example, the protrusion 61b extends from the end on the front side (+Z side) of the holder main body 61a to the end on the rear side (-Z side).

[0212] As shown in FIG. 38 , a plurality of busbars 62 are provided in this embodiment. Each busbar 62 is connected to at least one coil 53b. In this embodiment, each busbar 62 connects two or more coils 53b. Each of the plurality of busbars 62 includes a busbar main body 62e and a coil connection portion 62f. The busbar main body 62e is embedded in the busbar holder 61. The busbar main body 62e has a plate shape extending in the circumferential direction. The plate surface of the busbar main body 62e faces the radial direction. This allows the radial dimension of the busbar main body 62e to be smaller than when the plate surface of the busbar main body 62e faces the axial direction. This allows the radial thickness between the inner and outer circumferential surfaces of the busbar holder 61 to be reduced. This allows heat from the busbar 62 embedded in the busbar holder 61 to be easily transferred to the inner circumferential surface of the busbar holder 61. This makes it easier for heat from the busbars 62 to be released into the air that comes into contact with the inner circumferential surface of the busbar holder 61. Furthermore, by reducing the radial thickness between the inner and outer circumferential surfaces of the busbar holder 61, it is possible to increase the radial dimension of the portions of the multiple inner fins 51b that do not overlap with the busbar holder 61 in the axial direction. This further improves the heat dissipation of the stator 50 via the multiple inner fins 51b. As a result, the heat dissipation of the motor 100 can be further improved.

[0213] The coil connection portion 62f protrudes from the busbar main body 62e toward the rear side (-Z side). As shown in FIG. 37, the coil connection portion 62f protrudes from the busbar holder 61 toward the rear side. In this embodiment, the coil connection portion 62f is generally U-shaped and opens toward the rear side when viewed along the circumferential direction. An end of the conductor 53p constituting the coil 53b is inserted into the inside of each generally U-shaped coil connection portion 62f. The conductor 53p is connected to the coil connection portion 62f by, for example, welding. As a result, the coil connection portion 62f is connected to the coil 53b. The coil connection portion 62f is located radially inward of the coil 53b. As shown in FIG. 30, the coil connection portion 62f is embedded in the second resin portion 82. The rear end of the coil connection portion 62f is located closer to the rear than the rear end of the second annular portion 51f. In other words, the rear end of inner housing 51 is located closer to the front (+Z side) than the rear end of coil connection portion 62f. This makes it easier to connect the end of conducting wire 53p that forms coil 53b to coil connection portion 62f. This makes it easier to connect coil 53b and bus bar 62.

[0214] As shown in FIG. 38, each busbar 62 has two or more coil connection portions 62f. The multiple busbars 62 include a first busbar 62a, a second busbar 62b, a third busbar 62c, and a fourth busbar 62d. One first busbar 62a is provided. The circumferential dimension of the first busbar 62a is larger than the circumferential dimensions of the other busbars 62. The busbar main body 62e of the first busbar 62a has an arc shape with a central angle greater than 180° in a plan view along the axial direction. The first busbar 62a has three coil connection portions 62f. Two of the three coil connection portions 62f are connected to both circumferential ends of the busbar main body 62e of the first busbar 62a, respectively. The remaining coil connection portion 62f is connected to the circumferential center of the busbar main body 62e of the first busbar 62a.

[0215] A plurality of second busbars 62b are provided at intervals in the circumferential direction. In this embodiment, seven second busbars 62b are provided. The busbar main body 62e of each second busbar 62b is located closer to the rear (-Z side) than the busbar main body 62e of the first busbar 62a. The busbar main body 62e of each second busbar 62b is located at the same position in the radial direction as the busbar main body 62e of the first busbar 62a. The busbar main body 62e of some of the second busbars 62b is located at an interval rearward of the busbar main body 62e of the first busbar 62a. In other words, some of the busbar main body portions 62e of each second busbar 62b overlap with the busbar main body portion 62e of the first busbar 62a in a plan view along the axial direction. The second busbar 62b has two coil connection portions 62f. The two coil connection portions 62f are connected to both circumferential ends of the busbar main body 62e of the second busbar 62b, respectively.

[0216] A plurality of third busbars 62c are provided at intervals in the circumferential direction. In this embodiment, seven third busbars 62c are provided. The busbar body portions 62e of the third busbars 62c are located radially outward of the busbar body portions 62e of the first busbar 62a. The busbar body portions 62e of the third busbars 62c are located at the same positions in the axial direction as the busbar body portions 62e of the first busbar 62a. The busbar body portions 62e of some of the third busbars 62c are located radially outward of the busbar body portions 62e of the first busbar 62a at intervals. In other words, the busbar body portions 62e of some of the third busbars 62c overlap the busbar body portions 62e of the first busbar 62a when viewed radially. The third busbar 62c has two coil connection portions 62f. The two coil connection portions 62f are connected to both circumferential ends of the busbar main body 62e of the third busbar 62c, respectively.

[0217] A plurality of fourth busbars 62d are provided at intervals in the circumferential direction. In this embodiment, seven fourth busbars 62d are provided. The busbar main body 62e of each fourth busbar 62d is located closer to the rear (-Z side) than the busbar main body 62e of the third busbar 62c. The busbar main body 62e of each fourth busbar 62d is located at the same position in the radial direction as the busbar main body 62e of the third busbar 62c. The busbar main body 62e of each fourth busbar 62d is located at the same position in the axial direction as the busbar main body 62e of the second busbar 62b. At least a portion of the busbar main body 62e of each fourth busbar 62d is located rearward of, and spaced apart from, the busbar main body 62e of the third busbar 62c. That is, at least a portion of the busbar body 62e of each fourth busbar 62d overlaps with the busbar body 62e of the third busbar 62c in a plan view along the axial direction. At least a portion of the busbar body 62e of each fourth busbar 62d is disposed radially outward of and spaced from the busbar body 62e of the second busbar 62b. That is, at least a portion of the busbar body 62e of each fourth busbar 62d overlaps with the busbar body 62e of the second busbar 62b in a radial view. The fourth busbar 62d has two coil connection portions 62f. The two coil connection portions 62f are connected to both circumferential ends of the busbar body 62e of the fourth busbar 62d, respectively.

[0218] In the first busbar 62a and the second busbar 62b, each coil connection portion 62f protrudes radially outward from its corresponding busbar main body 62e. In the third busbar 62c and the fourth busbar 62d, each coil connection portion 62f protrudes radially inward from its corresponding busbar main body 62e. The coil connection portions 62f of the first busbar 62a and the second busbar 62b and the coil connection portions 62f of the third busbar 62c and the fourth busbar 62d at least partially overlap each other when viewed circumferentially. All of the coil connection portions 62f included in all of the busbars 62 are arranged side by side at intervals in the circumferential direction.

[0219] In this embodiment, each bus bar 62 connects two or more coils 53b together, but is not directly connected to an external power supply (not shown) that supplies current to the coils 53b. As described above, current is supplied to each coil 53b via the wiring members 57 drawn radially outward from the stator 50. In this manner, in this embodiment, the connection between the external power supply (not shown) and the coils 53b is made not via the bus bars 62 of the bus bar assembly 60 but via the wiring members 57 drawn radially outward from the stator 50. This prevents the bus bar assembly 60 from being disposed radially inward from the stator 50, thereby preventing the motor 100 from becoming larger in the radial direction, and allows an operator or the like to easily connect the external power supply (not shown) to the coils 53b. The number of bus bars 62 is not particularly limited as long as it is one or more.

[0220] Below, embodiments different from the above-described embodiments will be described. In the following description of each embodiment, the same configurations as those described above in the description of each embodiment may be omitted by appropriately assigning the same reference numerals. Furthermore, parts corresponding to the respective parts of the configurations described above in the description of each embodiment may be assigned the same names but different reference numerals, and differences from the above-described configurations may be described, while similar configurations to the above-described configurations may be omitted. Note that, as the configurations whose description is omitted in each of the following embodiments, configurations similar to the configurations described above in the description of each embodiment may be adopted within the scope of not being inconsistent.

[0221] Second Embodiment As shown in FIG. 39, in the motor 200 of the propulsion device 2000 of this embodiment, the preload member 274 has a peripheral wall 274d and a plate-shaped portion 274e. The peripheral wall 274d protrudes toward the front side (+Z side) from the nut portion 74a. In this embodiment, the peripheral wall 274d protrudes toward the front side from the radial inner edge of the front side surface of the nut portion 74a. As shown in FIG. 40, the peripheral wall 274d is cylindrical and surrounds the central axis J. In this embodiment, the peripheral wall 274d is cylindrical and centered on the central axis J.

[0222] The plate-shaped portion 274e protrudes radially inward from the front-side (+Z side) end of the peripheral wall 274d. The plate-shaped portion 274e is plate-shaped with its plate surface facing the axial direction. The plate-shaped portion 274e is annular and surrounds the central axis J. In this embodiment, the plate-shaped portion 274e is annular, the center of which coincides with the central axis J in a plan view along the axial direction. As shown in FIG. 39 , the plate-shaped portion 274e is located on the front side of the support shaft 211. The plate-shaped portion 274e is provided at a distance toward the front from the front end face of the support shaft 211. The radial inner edge of the plate-shaped portion 274e is provided at, for example, the same radial position as the radial inner edge of the front-side end of the support shaft 211.

[0223] As shown in FIG. 40, the plate-shaped portion 274e has an elongated hole 274f that penetrates the plate-shaped portion 274e in the axial direction. The elongated hole 274f extends in the circumferential direction. In this embodiment, a plurality of the elongated holes 274f are provided at intervals in the circumferential direction. In this embodiment, four elongated holes 274f are provided. A bolt 274g is passed axially through each elongated hole 274f from the front side (+Z side). The radial dimension of each elongated hole 274f is smaller than the outer diameter of the head of the bolt 274g. The head of the bolt 274g contacts the periphery of the elongated hole 274f on the front side surface of the plate-shaped portion 274e. Other configurations of the preload member 274 are similar to those of the preload member 74 of the first embodiment.

[0224] 39, the support shaft 211 of the mounting member 210 has a threaded hole 211a into which a bolt 274g is threaded, the bolt 274g being passed through the elongated hole 274f from the front side (+Z side). Therefore, by threading the bolt 274g into the threaded hole 211a, the circumferential position of the preload member 274 relative to the support shaft 211 can be fixed. This makes it possible to prevent the preload member 274 from unintentionally rotating about the central axis J and to prevent changes in the preloads applied to the first rolling bearing 71a and the second rolling bearing 71b. This makes it possible to prevent a decrease in the rigidity of the first rolling bearing 71a and the second rolling bearing 71b, and further to prevent the first rotor 20 and the second rotor 30 from tilting. The elongated hole 274f through which the bolt 274g is passed extends in the circumferential direction, so even if the circumferential position of the preload member 274 is shifted to adjust the preload applied to the first rolling bearing 71a and the second rolling bearing 71b, the bolt 274g can be easily tightened into the threaded hole 211a via the elongated hole 274f.

[0225] The screw holes 211a are recessed from the end face on the front side (+Z side) of the support shaft 211 to the rear side (-Z side). In this embodiment, a plurality of screw holes 211a are provided at intervals in the circumferential direction. In this embodiment, four screw holes 211a are provided. A bolt 274g is fastened into each screw hole 211a. Note that as long as a bolt 274g is fastened into at least one screw hole 211a, there may be a screw hole 211a into which a bolt 274g is not fastened. The other configurations of the support shaft 211 are the same as the other configurations of the support shaft 11 in the first embodiment. The other configurations of the mounting member 210 are the same as the other configurations of the mounting member 10 in the first embodiment.

[0226] Other configurations of the motor 200 are similar to other configurations of the motor 100 in the first embodiment. Other configurations of the propulsion device 2000 are similar to other configurations of the propulsion device 1000 in the first embodiment.

[0227] Third Embodiment As shown in FIG. 41 , in the motor 300 of the propulsion device 3000 of this embodiment, the stator 350 differs from the stator 50 of the first embodiment in the configuration of the stator cover 358. The cover through-hole 358f of the cover main body portion 358a of the stator cover 358 has a first portion 358p, a second portion 358q, and a third portion 358r. The first portion 358p is the rear-side (-Z side) end of the cover through-hole 358f. The second portion 358q is connected to the front-side (+Z side) of the first portion 358p. The inner diameter of the second portion 358q is larger than the inner diameter of the first portion 358p. A fourth step surface 358t facing the front side is provided between the inner circumferential surfaces of the first portion 358p and the second portion 358q. The third portion 358r is connected to the front side of the second portion 358q. The inner diameter of the third portion 358r is larger than the inner diameter of the second portion 358q. A fifth step surface 358u facing the front side is provided between the inner circumferential surface of the second portion 358q and the inner circumferential surface of the third portion 358r. The front end of the third portion 358r is the front end of the cover through-hole 358f. The other configurations of the stator cover 358 are similar to the other configurations of the stator cover 58 in the first embodiment.

[0228] In this embodiment, the second core portion 53d is fitted into the second portion 358q. An outer edge portion of the rear-side (-Z side) surface of the second core portion 53d contacts the fourth step surface 358t. The outer peripheral surface of the front-side (+Z side) portion of the second core portion 53d is spaced inward from the inner peripheral surface of the third portion 358r. An annular second seal member 358s surrounding the second core portion 53d is disposed between the outer peripheral surface of the front-side portion of the second core portion 53d and the inner peripheral surface of the third portion 358r. In other words, an annular second seal member 358s surrounding each second core portion 53d is disposed between the inner peripheral surface of each cover through-hole 358f and the outer peripheral surface of each second core portion 53d. Therefore, the second seal member 358s can further prevent resin from leaking from between the inner edge of the cover through-hole 358f and the outer edge of the second core portion 53d when molding the resin portion 80. Therefore, leakage of resin when molding the resin portion 80 can be further prevented.

[0229] Each second seal member 358s contacts the inner circumferential surface of the corresponding cover through hole 358f and the outer circumferential surface of the corresponding second core portion 53d. Each second seal member 358s seals between the inner circumferential surface of the corresponding cover through hole 358f and the outer circumferential surface of the corresponding second core portion 53d. The second seal member 358s contacts the fifth step surface 358u. Although not shown, the second seal member 358s has a shape similar to the outer shape of the second core portion 53d in a plan view along the axial direction. The second seal member 358s is, for example, an O-ring.

[0230] Other configurations of the stator 350 are similar to other configurations of the stator 50 in the first embodiment. Other configurations of the motor 300 are similar to other configurations of the motor 100 in the first embodiment. Other configurations of the propulsion device 3000 are similar to other configurations of the propulsion device 1000 in the first embodiment.

[0231] <Fourth embodiment> As shown in FIG. 42 , in the motor 400 of the propulsion device 4000 of this embodiment, the stator 450 has a first stator cover 458 and a second stator cover 459. The configuration of the first stator cover 458 is similar to the configuration of the stator cover 358 in the third embodiment. The second stator cover 459 is located on the rear side (-Z side) of the coil 53b. The second stator cover 459 is annular and surrounds the central axis J. The second stator cover 459 has a second cover main body portion 459a, a second inner annular wall 459b, and a second outer annular wall 459c. The second cover main body portion 459a is annular and surrounds the central axis J. The radial inner edge of the second cover main body portion 459a is located radially inward of the radial inner edge of the cover main body portion 358a of the first stator cover 458. The other configuration of the second cover main body portion 459a is similar to the other configuration of the cover main body portion 358a of the first stator cover 458, except that it is inverted in the axial direction.

[0232] The third core portion 53e of each electromagnet portion 53 is fitted into the inside of each cover through hole 459f in the second cover main body portion 459a. An annular third seal member 459s surrounding each third core portion 53e is disposed between the inner peripheral surface of each cover through hole 459f and the outer peripheral surface of each third core portion 53e. The third seal member 459s seals between the inner peripheral surface of each cover through hole 459f and the outer peripheral surface of each third core portion 53e. The third seal member 459s is, for example, an O-ring.

[0233] The second inner annular wall 459b protrudes from the radial inner edge of the second cover main body portion 459a toward the front side (+Z side). The second inner annular wall 459b has a cylindrical shape centered on the central axis J. The front end of the second inner annular wall 459b contacts the rear end face (-Z side) of the bus bar holder 61. More specifically, the front end of the second inner annular wall 459b contacts the radial inner edge of the rear end face (-Z side) of the bus bar holder 61.

[0234] The second outer annular wall 459c protrudes toward the front side (+Z side) from the radial outer edge of the second cover main body portion 459a. The second outer annular wall 459c is attached to the outer housing 452 in the same manner as the outer annular wall 58c of the first stator cover 458, except that it is inverted in the axial direction. The second outer annular wall 459c is located radially between a rear-side protruding wall 452d, which protrudes rearward from the rear-side (-Z side) end of the outer housing annular portion 452a of the outer housing 452, and the multiple outer fins 52b. The inner circumferential surface of the second outer annular wall 459c contacts the radially outer surface of the rear-side protruding wall 452d. The configuration of the outer housing annular portion 452a is similar to that of the outer housing annular portion 52a in the first embodiment, except that the rear-side end is located closer to the front than the rear-side ends of the multiple outer fins 52b. The configuration of the rear-side protruding wall 452d is similar to the configuration of the fourth protruding wall 52d, except that it is inverted in the axial direction.

[0235] In this embodiment, the resin portion 480 is molded by pouring resin into the interior surrounded by the inner housing 51, the outer housing 452, the first stator cover 458, the second stator cover 459, the second core portions 53d, and the third core portions 53e. In this embodiment, the second stator cover 459 is provided, so that the resin portion 480 can be molded without covering the rear side (-Z side) of the stator 450 with a jig or the like. Similarly to the first stator cover 458, the second stator cover 459 can prevent the resin from leaking to the rear side of the stator 450. Therefore, leakage of the resin during molding of the resin portion 480 can be further prevented. In this embodiment, annular third seal members 459s are disposed between the inner circumferential surface of each cover through-hole 459f and the outer circumferential surface of each third core portion 53e, surrounding each third core portion 53e. This makes it possible to further prevent resin from leaking between the inner circumferential surface of each cover through-hole 459f and the outer circumferential surface of each third core portion 53e when molding the resin portion 480. This makes it possible to further prevent resin from leaking when molding the resin portion 480.

[0236] Other configurations of the stator 450 are similar to other configurations of the stator 350 in the third embodiment. Other configurations of the motor 400 are similar to other configurations of the motor 300 in the third embodiment. Other configurations of the propulsion device 4000 are similar to other configurations of the propulsion device 3000 in the third embodiment.

[0237] Fifth Embodiment As shown in FIG. 43 , the motor 500 in the propulsion device 5000 of this embodiment includes a plurality of connecting columns 590. The plurality of connecting columns 590 extend in the axial direction. The plurality of connecting columns 590 are, for example, cylindrical and extend in the axial direction. At least a portion of each connecting column 590 is located between the first rotor 20 and the second rotor 30 in the axial direction. In this embodiment, each connecting column 590 is entirely located between the first rotor 20 and the second rotor 30 in the axial direction. Each connecting column 590 passes through the radially inner side of the stator 50 and the radially inner side of the bus bar holder 61 in the axial direction.

[0238] The connecting columns 590 are located radially inward of the inner fins 51b and the bus bar holder 61. The connecting columns 590 are fixed to at least one of the first rotor 20 and the second rotor 30. In this embodiment, the connecting columns 590 are fixed to both the first rotor 20 and the second rotor 30. The connecting columns 590 contact the front surface of the first rotor 20 and the rear surface of the second rotor 30. Therefore, the connecting columns 590 can maintain the axial distance between the first rotor 20 and the second rotor 30. By arranging the connecting columns 590 radially inward of the inner fins 51b, the axial distance between the first rotor 20 and the second rotor 30 can be maintained without arranging the connecting columns 590 radially outward of the stator 50. This makes it possible to provide the outer fins 52b on the outer peripheral surface of the outer housing annular portion 52a while preventing the stator 50 from becoming too large in the radial direction. Because multiple inner fins 51b and multiple outer fins 52b can be provided, the heat dissipation performance of the stator 50 can be improved, as described in the first embodiment. Furthermore, even if multiple connecting columns 590 are arranged radially inward of the multiple inner fins 51b, the flow of air flowing in the axial direction toward the multiple inner fins 51b is not obstructed, and the heat dissipation performance of the stator 50 is not reduced. Because the multiple connecting columns 590 rotate together with the first rotor 20 and the second rotor 30, the multiple connecting columns 590 agitate the air flowing radially inside the stator 50. This facilitates the flow of air radially inside the stator 50, making it easier for the air to come into contact with the multiple inner fins 51b. Therefore, the heat dissipation performance of the stator 50 can be further improved.

[0239] The multiple connecting pillars 590 are arranged at intervals in the circumferential direction. The multiple connecting pillars 590 are respectively arranged between the multiple first arms 22 and the multiple second arms 32 in the axial direction. In this embodiment, the rear side (-Z side) end of each connecting pillar 590 contacts the front side (+Z side) surface of each first arm 22 and is fixed to each first arm 22. In this embodiment, the front side end of each connecting pillar 590 contacts the rear side surface of each second arm 32 and is fixed to each second arm 32.

[0240] Other configurations of the motor 500 are similar to other configurations of the motor 100 in the first embodiment. Other configurations of the propulsion device 5000 are similar to other configurations of the propulsion device 1000 in the first embodiment.

[0241] Sixth Embodiment As shown in FIG. 44, in the motor 600 of the propulsion device 6000 of this embodiment, the number of second arms 632 of the second rotor 630 is six. As shown in FIG. 45, the second rotor annular portion 631a of the second rotor frame 631 of the second rotor 630 is rotatably supported on the support shaft 611 via a second bearing 671b. The second bearing 671b is, for example, a rolling bearing such as a ball bearing. The second bearing 671b may also be a plain bearing. The radial outer edge of the second rotor annular portion 631a is located radially outward from the radial outer edge of the second rotor annular portion 31a in the first embodiment. The radial outer edge of the second rotor annular portion 631a is located radially outward from the radial outer edge of the first rotor annular portion 621a. The other configurations of the second rotor 630 are similar to the other configurations of the second rotor 30 in the first embodiment.

[0242] In the first rotor frame 621 of the first rotor 620, the first rotor annular portion 621a is rotatably supported on the support shaft 611 via a first bearing 671a. The first bearing 671a is, for example, a rolling bearing such as a ball bearing. The first bearing 671a may also be a plain bearing. As shown in FIG. 46 , each of the multiple first arms 622 has a fixing hole 622u recessed from the front side (+Z side) surface of the first arm 622 toward the rear side (-Z side). Each fixing hole 622u is provided in a radially inner portion of the first arm 622. More specifically, each fixing hole 622u is provided in a portion of the first arm 622 that is located radially inward of the radially inner ends of the multiple inner fins 51b. Each fixing hole 622u is located radially inward of the rotor body 23. In this embodiment, the fixing hole 622u axially penetrates the first arm 622. The fixing holes 622u may be holes having a bottom on the rear side. As shown in Fig. 47, each fixing hole 622u has a circular shape in a plan view along the axial direction.

[0243] In this embodiment, the number of first arms 622 is six. The other configurations of each first arm 622 are the same as the other configurations of each first arm 22 in the first embodiment. The other configurations of the first rotor 620 are the same as the other configurations of the first rotor 20 in the first embodiment. Note that in Figures 44 to 47, the first rotor 620 and the second rotor 630 are shown in an appropriately simplified form.

[0244] As shown in FIG. 45 , in this embodiment, the motor 600 includes a plurality of connecting columns 690. The connecting columns 690 extend in the axial direction. For example, the connecting columns 690 have a cylindrical shape extending in the axial direction. At least a portion of each connecting column 690 is located axially between the first rotor 620 and the second rotor 630. Each connecting column 690 passes through the radially inner side of the stator 650 and the radially inner side of the bus bar holder 661 in the axial direction.

[0245] 46, each of the multiple connecting posts 690 has a post main body 691, a first contact portion 692, a second contact portion 693, and a fitting fixing portion 694. The post main body 691 extends in the axial direction. In this embodiment, the post main body 691 is cylindrical. The post main body 691 is located axially between the first rotor 620 and the second rotor 630.

[0246] The first contact portion 692 is connected to the rear end (-Z side) of the column main body 691. The second contact portion 693 is connected to the front end (+Z side) of the column main body 691. The first contact portion 692 and the second contact portion 693 are located axially between the first rotor 620 and the second rotor 630. In this embodiment, the entire connecting column 690, excluding the fitting fixing portion 694, is located axially between the first rotor 620 and the second rotor 630. The outer diameters of the first contact portion 692 and the second contact portion 693 are larger than the outer diameter of the column main body 691. The rear surface of the first contact portion 692 contacts the front surface of the first rotor 620. The front surface of the second contact portion 693 contacts the rear surface of the second rotor 630. The contact area between the connecting post 690 and each rotor can be increased by the first contact portion 692 and the second contact portion 693, which have an outer diameter larger than that of the post main body portion 691. Therefore, the connecting post 690 can be stably brought into contact with each rotor in the axial direction.

[0247] The outer diameter of the front-side (+Z side) portion of the first contact portion 692 connected to the pillar main body portion 691 increases toward the rear-side (-Z side). The outer diameter of the rear-side portion of the first contact portion 692 is the same as the outer diameter of the rear-side end of the front-side portion of the first contact portion 692. The rear-side surface of each of the first contact portions 692 of the multiple connecting pillars 690 contacts the front-side surfaces of the multiple first arms 622, respectively. In this embodiment, the rear-side surface of each first contact portion 692 contacts the front-side surface of a radially inner portion of each of the first arms 622.

[0248] The outer diameter of the rear-side (-Z side) portion of the second contact portion 693 connected to the column main body portion 691 increases toward the front-side (+Z side). The outer diameter of the front-side portion of the second contact portion 693 is the same as the outer diameter of the front-side end of the rear-side portion of the second contact portion 693. The front-side surface of each of the second contact portions 693 of the multiple connecting columns 690 contacts the rear-side surface of the second rotor annular portion 631a. The front-side surface of each of the second contact portions 693 is fixed to the rear-side surface of the second rotor annular portion 631a. In this way, each connecting column 690 is fixed to the second rotor 630. The method for fixing the second contact portion 693 to the second rotor annular portion 631a is not particularly limited, and may be adhesive bonding, welding, or screw fastening.

[0249] The fitting and fixing portion 694 is connected to the rear-side (-Z side) end of the first contact portion 692. In this embodiment, the fitting and fixing portion 694 has a cylindrical shape extending in the axial direction. Each fitting and fixing portion 694 of the multiple connecting posts 690 is fixed in a corresponding fixing hole 622u of the multiple first arms 622. This fixes each connecting post 690 to the first rotor 620. Because the fitting and fixing portion 694 is caught in the circumferential direction by the inner circumferential surface of the fixing hole 622u, the connecting post 690 is prevented from shifting in the circumferential direction relative to the first rotor 620. This prevents the connecting post 690 from coming off the first rotor 620. Therefore, the multiple connecting posts 690 can more appropriately maintain the axial distance between the first rotor 620 and the second rotor 630. Each fitting and fixing portion 694 is fitted into a corresponding fixing hole 622u. Each fitting and fixing portion 694 is press-fitted into and fixed in each fixing hole 622u. Note that each fitting and fixing portion 694 may be fixed in each fixing hole 622u by, for example, an adhesive.

[0250] 47, in this embodiment, each fixing hole 622u is provided in a portion of each first arm 622 that is circumferentially adjacent to the first rotor penetration portion 28. That is, each connecting pillar 690 is fixed to a portion of each first arm 622 that is circumferentially adjacent to the first rotor penetration portion 28. This makes it easier for each connecting pillar 690 to agitate the air passing through each first rotor penetration portion 28. This further improves the heat dissipation performance of the motor 600.

[0251] As shown in FIG. 46 , in a busbar assembly 660, the axial end face of a busbar holder 661 facing the inner fins 51b, i.e., the front-side (+Z) end face, has an inclined portion 661c facing the inner fins 51b. In this embodiment, the radially inner portion of the front-side end face of the busbar holder 661 is the inclined portion 661c. The inclined portion 661c moves away from the inner fins 51b in the axial direction as it moves radially inward. That is, the inclined portion 661c is positioned closer to the rear side (−Z side) as it moves radially inward. The radially inner edge of the inclined portion 661c is connected to the axial end of the inner circumferential surface of the busbar holder 661. Therefore, the inclined portion 661c can easily cause air that comes into contact with the inclined portion 661c from the front side to flow radially inward, thereby making it easier for the air to flow radially inward of the busbar holder 661. This allows air to flow more easily through the portions of the inner fins 51b that axially overlap with the bus bar holder 661, making it easier for air to come into contact with the inner fins 51b. This further improves the heat dissipation of the stator 650, and therefore the heat dissipation of the motor 600.

[0252] The radially outer edge of the inclined portion 661c is located radially inward and away from the outer peripheral surface of the busbar holder 661. The radially outer edge of the inclined portion 661c is located closer to the rear (-Z side) than a portion of the front-side (+Z side) end face of the busbar holder 661 that is located radially outward from the inclined portion 661c. As shown in FIG. 47 , in this embodiment, the inclined portion 661c is annular and surrounds the central axis J. More specifically, the inclined portion 661c is annular and has a center that coincides with the central axis J in a plan view along the axial direction. Note that in FIG. 46 , the busbar assembly 660 is shown simply by integrating the busbar holder 661 and the busbar.

[0253] In the inner housing 651 of the stator 650, the front end (+Z side) of the inner housing annular portion 651a is located closer to the front than the front end of the outer housing annular portion 652a of the outer housing 652. Unlike the inner housing annular portion 51a of the first embodiment, the inner housing annular portion 651a does not have a first groove 51d. Unlike the outer housing 52 of the first embodiment, the outer housing 652 does not have a fourth protruding wall 52d. The other configurations of the inner housing 651 are the same as the other configurations of the inner housing 51 of the first embodiment. The other configurations of the outer housing 652 are the same as the other configurations of the outer housing 52 of the first embodiment.

[0254] The stator 650 includes a front cover 658 and a rear cover 659. The front cover 658 partially covers the radial space between the front end (+Z side) of the inner housing annular portion 651a and the front end of the outer housing annular portion 652a. The front cover 658 is configured by stacking a first cover member 658g and a second cover member 658h in the axial direction. Each of the first cover member 658g and the second cover member 658h has a shape similar to that of the cover main body portion 58a in the first embodiment, except that the second groove 58d is not provided. The first cover member 658g and the second cover member 658h are located on the front side (+Z side) of the coil 53b. The first cover member 658g and the second cover member 658h are fitted radially between the inner housing annular portion 651a and the outer housing annular portion 652a. The first cover member 658g is made of ceramics. The second cover member 658h is made of resin. The second cover member 658h is made of, for example, FR4 (Flame Retardant Type 4). The second cover member 658h is located on the front side of the first cover member 658g. Note that the materials constituting the first cover member 658g and the second cover member 658h are not particularly limited.

[0255] The rear-side cover 659 covers at least a portion of the radially outer portion between the rear-side (-Z side) end of the inner housing annular portion 651a and the rear-side end of the outer housing annular portion 652a. The rear-side cover 659 has a plate-like plate surface in the axial direction. Although not shown, the rear-side cover 659 is annular and surrounds the central axis J. The radially outer edge of the rear-side cover 659 is fitted to the inner circumferential surface of the outer housing annular portion 652a. The rear-side cover 659 is made of ceramics. In this embodiment, the resin portion 680 has a portion located axially between the front-side cover 658 and the rear-side cover 659. The material constituting the rear-side cover 659 is not particularly limited.

[0256] As shown in FIG. 45, the mounting member 610 of this embodiment includes a support shaft 611 and a stator support member 610a. The support shaft 611 and the stator support member 610a are separate members. The stator support member 610a includes a tubular portion 618 and a plurality of stator support portions 12. The tubular portion 618 is cylindrical and has a center on a central axis J and is open on both axial sides. A portion of the support shaft 611 located closer to the rear (-Z side) than the first bearing 671a is fitted into the radially inner side of the tubular portion 618. The inner circumferential surface of the tubular portion 618 is fixed to the outer circumferential surface of the support shaft 611. In this embodiment, the plurality of stator support portions 12 extend radially outward from a portion of the outer circumferential surface of the tubular portion 618 located closer to the rear than the first rotor 620. In this embodiment, the radially inner ends of the multiple stator support parts 12 are indirectly connected to a part of the support shaft 611 that is positioned more rearward than the first rotor 620 via a cylindrical part 618 .

[0257] Other configurations of the motor 600 are similar to other configurations of the motor 100 in the first embodiment. Other configurations of the propulsion device 6000 are similar to other configurations of the propulsion device 1000 in the first embodiment.

[0258] Seventh Embodiment 48, the motor 700 of the propulsion device 7000 of this embodiment includes a first housing 700a and a second housing 700b. The first housing 700a covers the first rotor 720 from the rear side (-Z side). The second housing 700b covers the second rotor 730 from the front side (+Z side).

[0259] The first housing 700a has a first cover portion 700c and a first cylindrical portion 700d. The first cover portion 700c is located on the rear side (-Z side) of the first rotor 720 and covers the first rotor 720 from the rear side. The first cover portion 700c is disk-shaped with its center coinciding with the central axis J in a plan view along the axial direction. The first cylindrical portion 700d protrudes from the radial outer edge of the first cover portion 700c to the front side (+Z side). The first cylindrical portion 700d is cylindrical, centered on the central axis J and open to the front side.

[0260] The second housing 700b has a second lid portion 700e and a second tubular portion 700f. The second lid portion 700e is located on the front side (+Z side) of the second rotor 730 and covers the second rotor 730 from the front side. The second lid portion 700e is disk-shaped with its center coinciding with the central axis J in a plan view along the axial direction. The second tubular portion 700f protrudes from the radial outer edge of the second lid portion 700e toward the rear side (-Z side). The second tubular portion 700f is cylindrical, centered on the central axis J and open to the rear side.

[0261] The stator 750 includes an inner housing 751, an outer housing 752, and a plurality of electromagnet portions 53. The inner housing 751 is cylindrical and centered on a central axis J, with openings on both axial sides. The inner housing 751 is positioned radially inward of the plurality of electromagnet portions 53. A first rolling bearing 771a and a second rolling bearing 771b are fitted to the inner circumferential surface of the inner housing 751. The outer housing 752 surrounds the plurality of electromagnet portions 53. The outer housing 752 is cylindrical and centered on the central axis J, with openings on both axial sides. The inner housing 751, the outer housing 752, and the plurality of electromagnet portions 53 are connected to one another by a resin portion 780. Unlike the inner housing 51 of the first embodiment, the inner housing 751 does not have a plurality of inner fins 51b. Unlike the outer housing 52 in the first embodiment, the outer housing 752 does not have a plurality of outer fins 52b.

[0262] A first housing 700a and a second housing 700b are fixed to the outer housing 752. A radially outer portion of the outer housing 752 is sandwiched in the axial direction between a first cylindrical portion 700d and a second cylindrical portion 700f. The first cylindrical portion 700d and the second cylindrical portion 700f are fixed to the outer housing 752. The first cylindrical portion 700d, the second cylindrical portion 700f, and the outer housing 752 are fixed to one another by, for example, fastening them together with a plurality of bolts.

[0263] In this embodiment, the motor 700 includes a rotating shaft 711 instead of a support shaft. The rotating shaft 711 extends axially along the central axis J. The rotating shaft 711 has a generally cylindrical shape centered on the central axis J. The inner peripheral surface of the first rotor annular portion 721a of the first rotor frame 721 and the inner peripheral surface of the second rotor annular portion 731a of the second rotor frame 731 are fixed to the outer peripheral surface of the rotating shaft 711. The rotating shaft 711 is rotatable around the central axis J together with the first rotor 720 and the second rotor 730. The rotating shaft 711 axially penetrates the second cover portion 700e of the second housing 700b. The front end (+Z side) of the rotating shaft 711 is located closer to the front of the second housing 700b and is exposed to the outside of the motor 700. Although not shown, a propeller is attached to a portion of the rotary shaft 711 that is positioned further forward than the second housing 700b.

[0264] In the first rotor frame 721, the number of first arms 722 is four. In the second rotor frame 731, the number of second arms 732 is four. The other configuration of the first rotor 720 is the same as the other configuration of the first rotor 20 in the first embodiment. The other configuration of the second rotor 730 is the same as the other configuration of the second rotor 30 in the first embodiment. The other configuration of the motor 700 is the same as the other configuration of the motor 100 in the first embodiment. The other configuration of the propulsion device 7000 is the same as the other configuration of the propulsion device 1000 in the first embodiment.

[0265] The present invention is not limited to the above-described embodiments, and other configurations and methods may be adopted within the scope of the technical concept of the present invention. The number of magnets in the rotor body is not particularly limited, as long as it is at least one or more. The rotor body may have only one annular magnet. The rotor body may not have an annular member. In this case, the rotor body is composed of only one magnet. Furthermore, if the rotor body does not have an annular member and is composed of multiple magnets, the multiple magnets are fixed to each other, for example, with an adhesive. In each of the above-described embodiments, the rotor includes a first rotor and a second rotor, but this is not limited thereto. In each of the above-described embodiments, only one of the first rotor and the second rotor may be provided. The rotor support structure is not particularly limited. The stator support structure is not particularly limited. The arrangement of the busbar assembly is not particularly limited. A busbar assembly may not be provided. A stator cover may not be provided. The motor according to the present disclosure may be a double-stator axial-flux motor in which two stators are provided for one rotor, or an axial-flux motor with one rotor and one stator. The applications of the motor according to the present disclosure and the propulsion device are not particularly limited. The motor according to the present disclosure may be provided in equipment other than propulsion devices.

[0266] The present technology can be configured as follows. (1) A motor comprising: a rotor rotatable around a central axis; and a stator located on one axial side of the rotor, wherein the stator has a plurality of magnetic poles facing an end face of the rotor on one axial side; the rotor has an annular rotor body having at least one magnet, a rotor frame having a plurality of arms extending radially, and a first cover fixed to the rotor frame, wherein the magnetization direction of at least some or all of the magnets is axial, the plurality of arms are located on the other axial side of the rotor body, and the first cover covers at least a portion of the surface of the magnet facing one axial side. (2) The motor described in (1), wherein the rotor frame has a rotor annular portion surrounding the central axis, and each of the multiple arms extends radially outward from the outer peripheral surface of the rotor annular portion, is spaced apart from one another along the circumferential direction, and contacts the surface of the rotor body on the other axial side at either the surface facing one axial side of the arm or the circumferential edge of the arm. (3) The motor described in (2), wherein each of the plurality of arms has a retaining surface located radially outside the rotor body and facing radially inward, and a mounting surface located on the other axial side of the rotor body and facing one axial side, the mounting surface contacting the surface on the other axial side of the rotor body, and the retaining surface contacting the outer peripheral surface of the rotor body. (4) The motor described in (3), wherein the rotor body has an annular member made of a magnetic material located on the other axial side of the magnet and surrounding the central axis, the magnet is fixed to a surface on one axial side of the annular member, and the surface on the other axial side of the annular member is in contact with the mounting surface, and each of the multiple arms has an arm main body portion extending radially, a retaining wall protruding from a radially outer end of the arm main body portion to one axial side and having the retaining surface, and a first protrusion protruding radially inward from the axially one end of the retaining wall, and the annular member has an annular main body portion to which the magnet is fixed, and a plurality of outer protrusions protruding radially outward from an outer circumferential edge of the annular main body portion and arranged at intervals in the circumferential direction, and the multiple outer protrusions are respectively located on the other axial side of the first protrusions of the multiple arms, and radial outer edges of the multiple outer protrusions are in contact with the retaining surface, and each of the outer protrusions is in contact with a surface on the other axial side of each first protrusion or faces each other with a gap therebetween. (5) A motor as described in (4), wherein at least one of the plurality of arms has a protruding wall protruding to one axial side from a portion of the arm main body portion located radially inwardly of the retaining wall, and a second protruding portion protruding radially outward from an end portion of the protruding wall on one axial side, and the annular member has a first inner protruding portion protruding radially inward from an inner peripheral edge of the annular main body portion, and the first inner protruding portion is located on the other axial side of the second protruding portion and contacts or faces a surface on the other axial side of the second protruding portion with a gap therebetween. (6) The motor described in (5), wherein the first inner protrusion includes a first inner protrusion having a first through portion that penetrates the first inner protrusion in the axial direction, an inner edge of the first through portion having portions located on both sides in the circumferential direction, the second protrusion includes a second protrusion having a second through portion that penetrates the second protrusion in the axial direction, an inner edge of the second through portion having portions located on both sides in the circumferential direction, the first through portion and the second through portion at least partially overlap each other when viewed in a plane along the axial direction, a pin member extending in the axial direction is passed through the first through portion and the second through portion, and the pin member contacts portions of the inner edge of the first through portion that are located on both sides in the circumferential direction and portions of the inner edge of the second through portion that are located on both sides in the circumferential direction. (7) The annular member has a second inner protruding portion protruding radially inward from an inner peripheral edge of the annular main body portion, and the first cover has an annular top plate portion covering at least a part of a surface of the magnet facing one axial side, an inner wall protruding from the inner peripheral edge of the top plate portion toward the other axial side and positioned radially inside the rotor body, and a fixed portion protruding radially inward from an end portion of the inner wall on the other axial side and fixed to the arm with a bolt, the fixed portion having a through hole passing through the fixed portion in the axial direction, the through hole having a first hole portion having an arc-shaped inner edge recessed radially inward in a plan view along the axial direction, and a second hole portion positioned radially outward of the first hole portion. , wherein the second hole portion opens to a radially outer surface of the inner wall, at least a part of the second inner protrusion is located in the second hole portion, the radial inner edge of the second inner protrusion has an arc portion that is arc-shaped and recessed radially outward in a plan view along the axial direction, the inner edge of the first hole portion and the arc portion form a bolt through hole through which the bolt is passed from one axial side, the bolt is passed through the bolt through hole and fastened into a screw hole provided in the arm, and a head of the bolt presses the fixed portion and the second inner protrusion against the arm from one axial side. (8) A motor described in any one of (1) to (7), wherein, when viewed in a plane along the axial direction, the first cover has a ring-shaped portion surrounded by two inner and outer concentric circles, the centers of the two concentric circles coincide with the central axis, and when the difference in radii of the two concentric circles is called the width of the ring-shaped portion, the width of the ring-shaped portion is greater than the axial height of the entire first cover, and the first cover has a first cover recess on the other axial side, where the central portion in the width direction of the ring-shaped portion is recessed toward one axial side and extends along the ring-shaped portion to surround the central axis. (9) A motor described in any one of (1) to (8), wherein the rotor has a second cover arranged on the other axial side of the rotor body, and the second cover covers at least a portion of the surface on the other axial side of the rotor body and is fixed to at least one of the rotor frame and the first cover. (10) The motor described in (9), wherein the second cover has a bottom plate portion that is fan-shaped about the central axis when viewed in a plane along the axial direction, and a fixed wall that protrudes from the radial outer edge of the bottom plate portion toward the first cover, and the fixed wall is located radially outside the rotor body and is fixed to the first cover. (11) The motor described in (10), wherein the second cover has a claw protruding from the radial inner edge of the bottom plate portion to one axial side, the claw being positioned radially inside the rotor body and hooking onto the first cover from one axial side. (12) The motor described in (10) or (11), wherein the rotor has a plurality of the second covers arranged at intervals in the circumferential direction, and the plurality of second covers are each located between the arms adjacent to each other in the circumferential direction. (13) The motor according to any one of (1) to (12), wherein the first cover is made of fiber-reinforced plastic. (14) The motor according to any one of (1) to (13), wherein the rotor body has a plurality of the magnets, the plurality of magnets including a plurality of first magnets whose magnetization direction is axial and a plurality of second magnets whose magnetization direction is in a direction intersecting the axial direction, and the magnets are arranged in a Halbach array.

[0267] The configurations and methods described in this specification can be combined as appropriate within the scope of not being mutually contradictory. [Explanation of symbols]

[0268] 20, 620, 720...first rotor (rotor), 21...first rotor frame (rotor frame), 21a...first rotor annular portion (rotor annular portion), 22, 22a, 22b, 22c, 22d, 622...first arm (arm), 22f...arm main body portion, 22g...holding wall, 22h...first protruding portion, 22i...third protruding wall (protruding wall), 22j, 22k...second protruding portion, 22n...second Through portion, 22p... mounting surface, 22r... screw hole, 22t... holding surface, 23, 33... rotor body, 23a, 33a... annular member, 23c... annular body portion, 23d... outer protrusion portion, 23e, 23g, 23h... first inner protrusion portion, 23f... second inner protrusion portion, 23i... first through portion, 23j... arc portion, 23r... first magnet, 23s... second magnet, 23t... magnet, 24, 34...first cover, 24a...ring-shaped portion, 24b...fixed portion, 24c...first top plate portion (top plate portion), 24d...inner wall, 24g...through hole, 24h...first hole portion, 24i...second hole portion, 24t...first cover recess, 25, 35...second cover, 25a...bottom plate portion, 25b...fixing wall, 25c...claw, 26b...bolt, 26c...pin member, 26e...head portion, 26f...bolt bolt through-hole, 30, 630, 730... second rotor (rotor), 31... second rotor frame (rotor frame), 32... second arm (arm), 37a... second top plate portion (top plate portion), 50, 350, 450, 650, 750... stator, 53f, 53g... magnetic pole, 100, 200, 300, 400, 500, 600, 700... motor, C1, C2... concentric circle, J... central axis

Claims

1. a rotor rotatable about a central axis; a stator located on one axial side of the rotor; Equipped with the stator has a plurality of magnetic poles facing an end face of the rotor on one axial side, The rotor is an annular rotor body having at least one magnet; a rotor frame having a plurality of radially extending arms; a first cover fixed to the rotor frame; and At least some or all of the magnets have an axial magnetization direction; the plurality of arms are located on the other axial side of the rotor body, The first cover covers at least a portion of a surface of the magnet facing one axial side.

2. the rotor frame has a rotor annular portion surrounding the central axis, Each of the plurality of arms extending radially outward from the outer circumferential surface of the rotor annular portion, are circumferentially spaced apart from one another; and 2. The motor according to claim 1, wherein either a surface of the arm facing one axial side or a circumferential edge of the arm contacts a surface of the rotor body on the other axial side.

3. Each of the plurality of arms a retaining surface located radially outward of the rotor body and facing radially inward; a mounting surface located on the other axial side of the rotor body and facing one axial side; and the mounting surface contacts the surface on the other axial side of the rotor body, The motor according to claim 2 , wherein the retaining surface contacts an outer peripheral surface of the rotor body.

4. the rotor body has an annular member made of a magnetic material located on the other axial side of the magnet and surrounding the central axis, the magnet is fixed to a surface on one axial side of the annular member, the surface of the annular member on the other axial side contacts the mounting surface; Each of the plurality of arms an arm body portion extending in a radial direction; a retaining wall protruding from a radially outer end of the arm body portion toward one axial direction and having the retaining surface; a first protruding portion protruding radially inward from one axial end of the retaining wall; and The annular member is an annular main body portion to which the magnet is fixed; a plurality of outer protrusions that protrude radially outward from an outer circumferential edge of the annular main body and are spaced apart in a circumferential direction; and the plurality of outer protrusions are located on the other axial side of the first protrusion on the plurality of arms, radially outer edges of the plurality of outer protrusions contact the retaining surface; The motor according to claim 3 , wherein each of the outer protrusions contacts a surface on the other axial side of each of the first protrusions or faces the surface with a gap therebetween.

5. At least one of the plurality of arms a protruding wall protruding in one axial direction from a portion of the arm main body provided at a position radially inwardly spaced apart from the holding wall; a second protruding portion protruding radially outward from one axial end of the protruding wall; and the annular member has a first inner protrusion that protrudes radially inward from an inner peripheral edge of the annular main body portion, The motor according to claim 4 , wherein the first inner protrusion is located on the other axial side of the second protrusion and is in contact with a surface on the other axial side of the second protrusion or faces the surface with a gap therebetween.

6. the first inner protrusion includes a first penetration portion that penetrates the first inner protrusion in the axial direction, an inner edge of the first penetrating portion has portions located on both sides in the circumferential direction; the second protruding portion includes a second penetrating portion that penetrates the second protruding portion in the axial direction, an inner edge of the second penetrating portion has portions located on both sides in the circumferential direction; The first through portion and the second through portion at least partially overlap each other when viewed in a plan view along the axial direction, a pin member extending in an axial direction is passed through the first through portion and the second through portion; The motor according to claim 5 , wherein the pin member contacts portions of inner edges of the first through portion located on both sides in the circumferential direction and portions of inner edges of the second through portion located on both sides in the circumferential direction.

7. the annular member has a second inner protruding portion that protrudes radially inward from an inner peripheral edge of the annular main body portion, The first cover is a ring-shaped top plate portion covering at least a portion of a surface of the magnet facing one axial side; an inner wall projecting from an inner peripheral edge of the top plate portion toward the other axial side and positioned radially inward of the rotor body; a fixed portion that protrudes radially inward from the other axial end of the inner wall and is fixed to the arm with a bolt; and the fixed portion has a through hole that passes through the fixed portion in the axial direction, The through hole is a first hole portion having an inner edge that is arc-shaped and recessed radially inward in a plan view along the axial direction; a second hole portion located radially outward of the first hole portion; and the second hole portion opens to a radially outer surface of the inner wall, At least a portion of the second inner protrusion is located in the second hole, a radially inner edge of the second inner protrusion has an arc portion that is arc-shaped and recessed radially outward in a plan view along the axial direction, an inner edge of the first hole portion and the arc portion define a bolt through hole through which the bolt is inserted from one axial side; The bolt is passed through the bolt through-hole and fastened to a screw hole provided in the arm, The motor according to claim 4 , wherein the head of the bolt presses the fixed portion and the second inner protrusion against the arm from one axial side.

8. When viewed in a plan view along the axial direction, the first cover has an annular portion surrounded by two concentric circles, an inner circle and an outer circle, and the centers of the two concentric circles coincide with the central axis line, When the difference between the radii of the two concentric circles is referred to as the width of the annular portion, the width of the annular portion is greater than the height of the entire first cover in the axial direction, 2. The motor according to claim 1, wherein the first cover has a first cover recess on the other axial side, the first cover recess being recessed at a central portion in a width direction of the annular portion toward one axial side and extending around the central axis along the annular portion.

9. the rotor has a second cover disposed on the other axial side of the rotor body, The second cover is covering at least a portion of the surface on the other axial side of the rotor body; The motor according to claim 1 , wherein the rotor frame is fixed to at least one of the rotor frame and the first cover.

10. The second cover is A bottom plate portion that is fan-shaped about the central axis line in a plan view along the axial direction; a fixed wall protruding from a radial outer edge of the bottom plate portion toward the first cover; and The motor according to claim 9 , wherein the fixed wall is located radially outward of the rotor body and is fixed to the first cover.

11. the second cover has a claw that protrudes from a radial inner edge of the bottom plate portion to one side in the axial direction, The motor according to claim 10 , wherein the claw is located radially inward of the rotor body and hooked onto the first cover from one axial side.

12. the rotor has a plurality of the second covers arranged at intervals in the circumferential direction, The motor according to claim 10 , wherein the plurality of second covers are respectively positioned between the arms adjacent to each other in the circumferential direction.

13. The motor according to claim 1 , wherein the first cover is made of fiber-reinforced plastic.

14. the rotor body has a plurality of the magnets, 9. The motor according to claim 1, wherein the plurality of magnets include a plurality of first magnets whose magnetization direction is in the axial direction and a plurality of second magnets whose magnetization direction is in a direction intersecting the axial direction, and are arranged in a Halbach array.

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