Motor

Abstract

A motor according to the present invention comprises: a rotor that can rotate about the central axis; and a stator that faces the rotor with an interval therebetween in the axial direction. The rotor has a plurality of magnets arranged along the circumferential direction, and holding parts for holding the plurality of magnets. The holding parts have a first metal holding part and a second resin holding part that holds the first holding part and the plurality of magnets.

Description

motor

[0001] This application claims priority from Japanese Patent Application No. 2024-049117, filed on March 26, 2024, the contents of which are incorporated herein by reference.

[0002] As an axial gap motor in which the rotor is arranged axially opposite the stator, a motor has been disclosed in which the rotor has a disk-shaped rotor core and a plurality of permanent magnets held by the rotor core and arranged circumferentially (for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2001-57753

[0004] In the motor described in Patent Document 1, the rotor core to which multiple permanent magnets are fixed is made of metal, making it difficult to reduce the rotor's weight. Simply replacing the stator core with a disk-shaped resin member in an attempt to reduce the rotor's weight reduces the rotor's rigidity. This increases the axial deflection of the rotor due to the magnetic force between each permanent magnet and the stator, increasing the amount of fluctuation in the axial spacing between each permanent magnet and the stator during motor operation. This makes it difficult to stabilize the magnetic force between each permanent magnet and the stator, reducing the stability of the motor's operation.

[0005] In view of the above circumstances, one aspect of the present invention aims to provide a motor that can reduce the weight of the rotor while suppressing a decrease in operational stability.

[0006] One aspect of the motor of the present invention includes a rotor rotatable about a central axis and a stator facing the rotor at an axial distance. The rotor has a plurality of magnets arranged along the circumferential direction and a holder for holding the plurality of magnets. The holder has a first holder made of metal and a second holder made of resin that holds the first holder and the plurality of magnets.

[0007] According to one aspect of the present invention, in a motor, it is possible to reduce the weight of the rotor while suppressing a decrease in operational stability.

[0008] FIG. 1 is a perspective view showing a motor of the first embodiment. FIG. 2 is a cross-sectional view showing the motor of the first embodiment. FIG. 3 is a cross-sectional view showing the motor of the first embodiment, taken along III-III in FIG. 2. FIG. 4 is a perspective view showing a first holding portion of the first embodiment. FIG. 5 is a cross-sectional view showing the motor of the first embodiment, taken along VV in FIG. 3. FIG. 6 is a cross-sectional view showing a portion of the motor of the first embodiment. FIG. 7 is a cross-sectional view showing a motor of a modified example of the first embodiment. FIG. 8 is a perspective view showing a motor of the second embodiment. FIG. 9 is a cross-sectional view showing a motor of the second embodiment. FIG. 10 is a perspective view showing a rotor of the second embodiment. FIG. 11 is a perspective view showing the first holding portion of the second embodiment. FIG. 12 is a cross-sectional view showing a portion of the rotor of the second embodiment. FIG. 13 is a cross-sectional view showing a portion of the motor of the second embodiment. FIG. 14 is a perspective view showing a rotor of the third embodiment. FIG. 15 is a perspective view showing the first holding portion of the third embodiment. FIG. 16 is a cross-sectional view showing a rotor of the third embodiment.

[0009] Hereinafter, motors according to embodiments of the present invention will be described with reference to the drawings. Note that the scope of the present invention is not limited to the following embodiments, and can be modified as desired within the scope of the technical concept of the present invention. In addition, in the following drawings, the scale and number of components may differ from the actual structure in order to make each component easier to understand.

[0010] In the following description, the Z axis is indicated in the figures as appropriate. The Z axis is the direction in which the central axis J of the embodiment described below extends. The central axis J shown in each figure is a virtual axis. In the following description, the direction in which the central axis J extends, i.e., the direction parallel to the Z axis, is referred to as the "axial direction." The radial direction centered on the central axis J is simply referred to as the "radial direction." The circumferential direction centered on the central axis J is simply referred to as the "circumferential direction." The circumferential direction is indicated by an arrow θ in each figure. The side of the axial direction toward which the Z axis arrow points (+Z side) is referred to as the "upper side" or "one axial side." The side of the axial direction opposite to the side toward which the Z axis arrow points (-Z side) is referred to as the "lower side" or "other axial side." Note that the terms "upper side" and "lower side" are simply names used to describe the relative positional relationships of the various components, and the actual positional relationships may be other than those indicated by these names.

[0011] First Embodiment As shown in Fig. 1, a motor 10 of this embodiment is a disk-shaped motor centered on a central axis J. The motor 10 is a thin motor whose axial dimension is smaller than its radial dimension. As shown in Fig. 2, the motor 10 is an axial gap motor in which a stator 20 and a rotor 30 face each other in the axial direction with a gap between them. The motor 10 includes a case 11, a stator 20, a rotor 30, and a shaft 48. The motor 10 includes a stator 20 on each axial side of the rotor 30.

[0012] The case 11 has a substantially cylindrical shape centered on a central axis J. The case 11 accommodates the stator 20, the rotor 30, and the shaft 48 therein. The case 11 also holds the stator 20, the rotor 30, and the shaft 48. The case 11 has a first case 12 and a second case 16.

[0013] The first case 12 is the upper portion of the case 11. The first case 12 is generally cylindrical and protrudes in the axial direction about the central axis J. The first case 12 is open downward. The first case 12 has a top wall 13 and a first peripheral wall 14.

[0014] As shown in Fig. 1, the top wall portion 13 has a substantially circular plate shape centered on the central axis J. As shown in Fig. 2, the top wall portion 13 is disposed above the stator 20 and the rotor 30. The top wall portion 13 is provided with a first hole portion 13a, a first bearing holder 13c, and a first accommodating hole 13e. The first hole portion 13a is a hole that penetrates the top wall portion 13 in the axial direction. When viewed in the axial direction, the first hole portion 13a is a substantially circular hole centered on the central axis J.

[0015] The first bearing holder 13c protrudes downward from the ceiling wall 13. The first bearing holder 13c is generally cylindrical and centered on the central axis J. The first bearing holder 13c opens downward. The first bearing holder 13c is located radially outward from the first hole 13a. A first bearing 51 is attached to the inner peripheral surface of the first bearing holder 13c. The first bearing 51 is generally annular and centered on the central axis J. In this embodiment, the first bearing 51 is a ball bearing. The first bearing 51 may also be a sliding bearing.

[0016] The first accommodating hole 13e is a recess recessed upward from the downward-facing surface of the top wall portion 13. When viewed in the axial direction, the first accommodating hole 13e has a substantially annular shape centered on the central axis J. The first accommodating hole 13e is provided radially outward of the first bearing holder portion 13c.

[0017] The first circumferential wall portion 14 has a generally cylindrical shape that protrudes in the axial direction about the central axis J. The first circumferential wall portion 14 surrounds the stator 20 and the rotor 30 from the radially outer side. The first circumferential wall portion 14 is provided with second holes 14a. The second holes 14a are holes that penetrate the first circumferential wall portion 14 in the axial direction. When viewed in the axial direction, the second holes 14a are generally circular. As shown in FIG. 1 , in this embodiment, the first circumferential wall portion 14 is provided with six second holes 14a. The number of second holes 14a provided in the first circumferential wall portion 14 may be five or less, or seven or more. The second holes 14a are provided at generally equal intervals along the circumferential direction.

[0018] The second case 16 is the lower portion of the case 11. The second case 16 is generally cylindrical and protrudes axially about the central axis J. The second case 16 is open on the upper side. The second case 16 is fixed to the lower end of the first case 12. The second case 16 has a bottom wall portion 17 and a second peripheral wall portion 18.

[0019] The bottom wall portion 17 has a generally circular plate shape centered on the central axis J. The bottom wall portion 17 is disposed below the stator 20 and the rotor 30. The bottom wall portion 17 is provided with a second bearing holder 17a and a second accommodating hole 17c.

[0020] The second bearing holder 17a protrudes upward from the bottom wall portion 17. The second bearing holder 17a is generally cylindrical and centered on the central axis J. The second bearing holder 17a opens upward. A second bearing 52 is attached to the inner peripheral surface of the second bearing holder 17a. The second bearing 52 is generally annular and centered on the central axis J. In this embodiment, the second bearing 52 is a ball bearing. The second bearing 52 may also be a sliding bearing.

[0021] The second accommodating hole 17c is a recess recessed downward from the upward-facing surface of the bottom wall portion 17. When viewed in the axial direction, the second accommodating hole 17c has a substantially annular shape centered on the central axis J. The second accommodating hole 17c is provided radially outward of the second bearing holder portion 17a. When viewed in the axial direction, the second accommodating hole 17c overlaps with the first accommodating hole 13e.

[0022] The second circumferential wall portion 18 has a generally cylindrical shape that protrudes in the axial direction about the central axis J. The second circumferential wall portion 18 surrounds the stator 20 and the rotor 30 from the radially outer side. The upper end of the second circumferential wall portion 18 contacts the lower end of the first circumferential wall portion 14 in the axial direction. The second circumferential wall portion 18 is provided with threaded holes 18a. The threaded holes 18a are female threaded holes recessed downward from the upper surface of the second circumferential wall portion 18. When viewed in the axial direction, the threaded holes 18a are generally circular. Although not shown, in this embodiment, the second circumferential wall portion 18 is provided with six threaded holes 18a. The threaded holes 18a are provided at generally equal intervals along the circumferential direction. When viewed in the axial direction, the threaded holes 18a overlap with different second hole portions 14a. When the screws 61 are passed axially through the second holes 14a and tightened into the screw holes 18a, the second peripheral wall 18 is fixed to the first peripheral wall 14. As a result, the second case 16 is fixed to the first case 12.

[0023] The stator 20 is disposed opposite the rotor 30 with an axial gap therebetween. In this embodiment, the motor 10 includes two stators 20. The two stators 20 include a first stator 21 and a second stator 26. In this embodiment, the motor 10 is a double-stator, single-rotor axial gap motor.

[0024] The first stator 21 is disposed above the rotor 30. The first stator 21 faces the rotor 30 with a gap therebetween in the axial direction. The first stator 21 has a stator core 22, a coil portion 23, and a ring member 24.

[0025] The stator core 22 has a substantially annular shape centered on the central axis J. The stator core 22 has a back yoke 22a and teeth 22b. The back yoke 22a has a substantially annular plate shape centered on the central axis J. The plate surface of the back yoke 22a faces the axial direction. The back yoke 22a is disposed inside the first accommodating hole 13e. The back yoke 22a is fixed to the inner surface of the first accommodating hole 13e. This fixes the stator core 22 to the top wall portion 13. Therefore, the first stator 21 is fixed to the first case 12. In this embodiment, the back yoke 22a is adhesively fixed to the inner surface of the first accommodating hole 13e with an adhesive. The back yoke 22a may be press-fitted into the first accommodating hole 13e.

[0026] The teeth 22b are columnar and protrude downward from the back yoke 22a. The teeth 22b face the rotor 30 with a gap in the axial direction. The stator core 22 has a plurality of teeth 22b. Although not shown in the figures, in this embodiment, the stator core 22 has 12 teeth 22b. The number of teeth 22b included in the stator core 22 may be 11 or less, or 13 or more. The teeth 22b are arranged at approximately equal intervals in the circumferential direction.

[0027] The coil portions 23 are attached to the tooth portions 22b. The coil portions 23 are formed by coils wound around the outer peripheral surfaces of the tooth portions 22b. The first stator 21 has a plurality of coil portions 23. In this embodiment, the first stator 21 has twelve coil portions 23. Each coil portion 23 is attached to a different tooth portion 22b. The coil portions 23 are arranged at approximately equal intervals along the circumferential direction. Although not shown, each coil portion 23 is electrically connected to a power supply device. When current is supplied to each coil portion 23 from the power supply device, each coil portion 23 forms an electromagnet with its magnetic poles facing in the axial direction.

[0028] The ring member 24 is an annular plate that surrounds the lower portions of the teeth 22b. The plate surface of the ring member 24 faces the axial direction. The teeth 22b are inserted inside the ring member 24. The ring member 24 is fixed to the teeth 22b. In this embodiment, the first stator 21 has 12 ring members 24. Each ring member 24 is fixed to a different tooth 22b. The circumferential and radial dimensions of each ring member 24 are greater than the circumferential and radial dimensions of the teeth 22b. The upward-facing surface of each ring member 24 contacts the coil portion 23 in the axial direction. This prevents the coil portions 23 from moving downward relative to the teeth 22b.

[0029] The second stator 26 is disposed below the rotor 30. The second stator 26 faces the rotor 30 with a gap in the axial direction. The second stator 26 has a stator core 27, a coil portion 28, and a ring member 29. In the present embodiment, the shape, arrangement, etc. of each part constituting the second stator 26 are plane-symmetrical to the shape, arrangement, etc. of each part constituting the first stator 21 described above, with respect to a plane perpendicular to the axial direction. Therefore, in the following description of the second stator 26, description of the same shape, arrangement, etc. as the first stator 21 may be omitted.

[0030] The stator core 27 has a substantially annular shape centered on the central axis J. The stator core 27 has a back yoke 27a and teeth 27b. The back yoke 27a has a substantially annular plate shape centered on the central axis J. The back yoke 27a is disposed inside the second accommodating hole 17c. The back yoke 27a is fixed to the inner surface of the second accommodating hole 17c. In this way, the second stator 26 is fixed to the second case 16.

[0031] The teeth 27b are columnar and protrude upward from the back yoke 27a. The teeth 27b face the rotor 30 with a gap in the axial direction. In this embodiment, the stator core 27 has 12 teeth 27b. The number of teeth 27b included in the stator core 27 may be 11 or less, or 13 or more.

[0032] The coil portions 28 are attached to the tooth portions 27b. The coil portions 28 are formed by coils wound around the outer peripheral surfaces of the tooth portions 27b. In this embodiment, the second stator 26 has 12 coil portions 28. Each coil portion 28 is attached to a different tooth portion 27b. Although not shown, each coil portion 28 is electrically connected to a power supply device. When current is supplied to each coil portion 28 from the power supply device, each coil portion 28 forms an electromagnet with its magnetic poles facing in the axial direction.

[0033] The ring members 29 are annular plate-shaped and surround the upper portions of the teeth 27b. The ring members 29 are fixed to the teeth 27b. In this embodiment, the second stator 26 has 12 ring members 29. Each ring member 29 is fixed to a different tooth 27b. The downward surface of each ring member 29 contacts the coil portion 28 in the axial direction. This makes it possible to prevent the coil portions 28 from moving upward relative to the teeth 27b.

[0034] The rotor 30 has a substantially annular shape centered on the central axis J. In the axial direction, the rotor 30 is disposed between the first stator 21 and the second stator 26. The rotor 30 faces each of the first stator 21 and the second stator 26 at an interval in the axial direction. The rotor 30 is rotatable about the central axis J. The rotor 30 has a holding portion 31 and a magnet 39.

[0035] The magnet 39 has a plate shape extending in a direction perpendicular to the axial direction. As shown in FIG. 3 , when viewed from the axial direction, the magnet 39 has a generally trapezoidal shape with its long sides positioned radially outward and its short sides positioned radially inward. In this embodiment, the rotor 30 has a plurality of magnets 39. The magnets 39 are arranged along the circumferential direction. More specifically, the magnets 39 are arranged at approximately equal intervals along the circumferential direction. The magnets 39 may be in contact with each other in the circumferential direction. As shown in FIG. 2 , each magnet 39 is housed inside the retaining portion 31. Each magnet 39 faces the teeth 22 b of the first stator 21 in the axial direction. Each magnet 39 faces the teeth 27 b of the second stator 26 in the axial direction. The magnets 39 are magnetized in the axial direction. The magnetic poles formed on the upper surfaces of a pair of magnets 39 arranged adjacent to each other in the circumferential direction are different from each other. The magnetic poles formed on the lower surfaces of a pair of magnets 39 arranged adjacent to each other in the circumferential direction are different from each other. When a current is supplied to each of the coils 23, 28 from a power supply (not shown), a magnetic field is generated between each of the magnets 39 and the teeth 22 b, 27 b. This causes a magnetic force to be applied to each of the magnets 39 in the axial direction. In other words, a magnetic force to be applied to the rotor 30 in the axial direction.

[0036] The holding portion 31 is substantially annular and centered on the central axis J. The holding portion 31 holds a plurality of magnets 39. The holding portion 31 has a first holding portion 32 and a second holding portion 40. The second holding portion 40 is located radially outward of the first holding portion 32. The second holding portion 40 holds the first holding portion 32.

[0037] As shown in FIG. 4 , the first holding portion 32 has a substantially circular ring shape centered on the central axis J. In this embodiment, the first holding portion 32 is made of metal. For example, aluminum can be used as a material for the first holding portion 32. In this embodiment, the first holding portion 32 is made of aluminum. The first holding portion 32 has an annular portion 33 and a plurality of protrusions 35.

[0038] The annular portion 33 has a generally annular plate shape centered on the central axis J. As shown in FIG. 3 , the annular portion 33 is disposed radially inward of the second holding portion 40. The annular portion 33 is disposed radially inward of each of the plurality of magnets 39. That is, each of the plurality of magnets 39 is disposed radially outward of the annular portion 33. As shown in FIG. 2 , the surface of the annular portion 33 facing upward is positioned radially inward. The surface of the annular portion 33 facing downward is positioned radially inward. As a result, the axial dimension of the annular portion 33 increases radially inward. Therefore, the axial rigidity of the annular portion 33 can be increased compared to a case in which the axial dimension of the annular portion 33 is the same as the axial dimension of the radial outer edge of the annular portion 33 throughout the entire radial direction.

[0039] 4 , each of the plurality of protrusions 35 protrudes radially outward from the annular portion 33. The plurality of protrusions 35 includes a first protrusion 36 and a second protrusion 37.

[0040] The first protrusion 36 has a plate shape that protrudes radially outward from the annular portion 33. The plate surface of the first protrusion 36 faces the circumferential direction. As shown in FIG. 5 , when viewed in the circumferential direction, the first protrusion 36 has a generally trapezoidal shape with its axially extending short side positioned radially outward and its axially extending long side positioned radially inward. The surface of the first protrusion 36 facing upward is positioned radially inward. The surface of the first protrusion 36 facing downward is positioned radially inward. As a result, the axial dimension of the first protrusion 36 increases radially inward. Therefore, the axial rigidity of the first protrusion 36 can be increased compared to when the axial dimension of the first protrusion 36 is the same as the axial dimension of the radial outer edge of the first protrusion 36 throughout the entire radial direction.

[0041] The radially outer portion of the first protrusion 36 is located inside the second retaining portion 40. As shown in FIG. 3 , the radially outer portion of the first protrusion 36 is located between a pair of magnets 39 arranged adjacent to each other in the circumferential direction. That is, a portion of the first protrusion 36 is located between the pair of magnets 39 arranged adjacent to each other in the circumferential direction. This allows the radially outer end of the first protrusion 36 to be located radially outward from the radially inner end of the magnet 39. The first protrusion 36 shown by the dashed line in FIG. 6 is a projection of the shape of the first protrusion 36 as viewed from the circumferential direction. The maximum axial dimension T1 of the portion of the first protrusion 36 that overlaps with the teeth 22b, 27b as viewed from the axial direction is less than the axial dimension Tm of the magnet 39. Therefore, the axial dimension of the portion of the first protrusion 36 that overlaps with the teeth 22b, 27b as viewed from the axial direction is less than the axial dimension Tm of the magnet 39. Furthermore, the axial dimension of a portion of the first protrusion 36 that is radially inward of the teeth 22 b, 27 b is greater than the axial dimension Tm of the magnet 39. In other words, the axial dimension of at least a portion of the first protrusion 36 that does not overlap with the teeth 22 b, 27 b when viewed in the axial direction is greater than the axial dimension Tm of the magnet 39.

[0042] As shown in Fig. 4, the plurality of protrusions 35 includes a plurality of first protrusions 36. In this embodiment, the plurality of protrusions 35 includes twelve first protrusions 36. The first protrusions 36 are spaced apart from one another in the circumferential direction. As shown in Fig. 3, a portion of each of the plurality of first protrusions 36 is located between different pairs of magnets 39. As shown in Fig. 5, a radially outer portion of each first protrusion 36 is located inside the second holding portion 40.

[0043] As shown in FIG. 4 , the second protrusion 37 has a plate shape that protrudes radially outward from the annular portion 33. The plate surface of the second protrusion 37 faces the axial direction. The radially outer end of the second protrusion 37 is located radially inward relative to the radially outer end of the first protrusion 36. As shown in FIG. 2 , when viewed in the circumferential direction, the second protrusion 37 has a generally rectangular shape with long sides extending radially. The second protrusion 37 protrudes radially outward from the axial center of the annular portion 33. The second protrusion 37 is located radially inward relative to the magnet 39. The second protrusion 37 faces the magnet 39 with a radial gap between them. The second protrusion 37 is located inside the second holding portion 40. In other words, at least a portion of the second protrusion 37 is located inside the second holding portion 40. A portion of the second protrusion 37 may be located outside the second holding portion 40. As described above, the radially outer portion of the first protrusion 36 is located inside the second holding portion 40. Therefore, at least a portion of each of the multiple protrusions 35 is located inside the second holding portion 40.

[0044] As shown in FIG. 4 , the multiple protrusions 35 include multiple second protrusions 37. In this embodiment, the multiple protrusions 35 include twelve second protrusions 37. The second protrusions 37 are spaced apart from one another in the circumferential direction. Each second protrusion 37 is located between a pair of different first protrusions 36. As a result, the second protrusions 37 and the first protrusions 36 are alternately arranged in the circumferential direction. Each second protrusion 37 is connected to each of a pair of first protrusions 36 that are adjacent to each other in the circumferential direction. As shown in FIG. 2 , each of the multiple second protrusions 37 faces a different magnet 39 in the radial direction.

[0045] As shown in FIG. 5 , the second retaining portion 40 has a substantially circular ring shape centered on the central axis J. The second retaining portion 40 surrounds the annular portion 33 from the radially outer side. In this embodiment, the second retaining portion 40 is made of resin. This allows the retaining portion 31 to be lighter than when the second retaining portion 40 is made of metal, i.e., when the entire retaining portion 31 is made of metal. This therefore allows the rotor 30 to be lighter. In this embodiment, the second retaining portion 40 is molded by insert molding, using the first retaining portion 32 and the plurality of magnets 39 as insert members. At least a portion of the first retaining portion 32 and the plurality of magnets 39 are embedded within the second retaining portion 40. This allows the second retaining portion 40 to hold the first retaining portion 32 and the plurality of magnets 39. As shown in FIG. 3 , the second retaining portion 40 is provided with a magnet retaining hole 41 and a first hole 42. As shown in FIG. 2 , the second retaining portion 40 is provided with a second hole 43.

[0046] The magnet holding holes 41 are holes that penetrate the second holding portion 40 in the axial direction. As shown in FIG. 3 , when viewed axially, the magnet holding holes 41 are generally trapezoidal in shape, with the long sides positioned radially outward and the short sides positioned radially inward. In this embodiment, twelve magnet holding holes 41 are provided in the second holding portion 40. The magnet holding holes 41 are provided at approximately equal intervals along the circumferential direction. A different magnet 39 is disposed inside each magnet holding hole 41. Each magnet 39 is held by the inner surface of the magnet holding hole 41. In this way, the second holding portion 40 holds each of the multiple magnets 39. In other words, the holding portion 31 holds each of the multiple magnets 39. As shown in FIG. 2 , the upward-facing surface of each magnet 39 is exposed from the second holding portion 40 and faces the teeth 22b of the first stator 21 in the axial direction. The downward-facing surface of each magnet 39 is exposed from the second holding portion 40 and faces the teeth 27b of the second stator 26 in the axial direction.

[0047] As shown in FIG. 3 , the first hole portions 42 are recesses recessed radially outward from the inner circumferential surface of the second retaining portion 40. When viewed in the axial direction, the first hole portions 42 are generally rectangular with their long sides extending radially. In this embodiment, twelve first holes 42 are provided in the second retaining portion 40. The first holes 42 are provided at approximately equal intervals along the circumferential direction. The radially outer portions of the first holes 42 are located between pairs of magnets 39 that are adjacent to each other in the circumferential direction. As shown in FIG. 5 , the radially outer portions of different first protrusions 36 are located inside each first hole 42. As a result, the radially outer portions of each first protrusion 36 are located inside the second retaining portion 40. The radially outer portions of each first protrusion 36 are held by the inner surface of the first hole portion 42. As a result, the second retaining portion 40 holds the first retaining portion 32.

[0048] As shown in FIG. 2 , the second hole portion 43 is a recess recessed radially outward from the inner circumferential surface of the second retaining portion 40. When viewed in the circumferential direction, the second hole portion 43 has a generally rectangular shape with its long sides extending radially. Although not shown, in this embodiment, twelve second hole portions 43 are provided in the second retaining portion 40. The second hole portions 43 are provided at generally equal intervals along the circumferential direction. A different second protrusion portion 37 is disposed inside each second hole portion 43. As a result, each second protrusion portion 37 is located inside the second retaining portion 40. Each second protrusion portion 37 is held by the inner surface of the second hole portion 43. As a result, the second retaining portion 40 holds the first retaining portion 32.

[0049] The shaft 48 has a generally cylindrical shape extending in the axial direction about the central axis J. The shaft 48 is disposed radially inward of the stator 20 and the rotor 30. In this embodiment, the shaft 48 is connected to the first retaining portion 32. In this embodiment, the shaft 48 and the first retaining portion 32 are different portions of the same single member. The shaft 48 and the first retaining portion 32 may be different members. In this case, the first retaining portion 32 is fixed to the outer peripheral surface of the shaft 48. The shaft 48 is supported by the first bearing 51 and the second bearing 52 so as to be rotatable about the central axis J. This allows the rotor 30 to rotate about the central axis J. The upper end of the shaft 48 protrudes outside the case 11 through the first hole portion 13a. A shaft hole portion 48a is provided in the shaft 48.

[0050] The shaft hole 48a is a female threaded hole recessed downward from the upward-facing surface of the shaft 48. As shown in FIG. 1, the shaft hole 48a is substantially circular when viewed in the axial direction. In this embodiment, the shaft 48 is provided with four shaft holes 48a. The shaft holes 48a are spaced apart in the circumferential direction. When screws are passed through holes provided in a rotated body (not shown) and tightened into the shaft holes 48a, the rotated body is attached to the shaft 48. This allows the motor 10 to rotate the rotated body about the central axis J.

[0051] When current is sequentially supplied from a power supply (not shown) to the multiple coil portions 23 of the first stator 21 and the multiple coil portions 28 of the second stator 26, the coil portions 23, 28 sequentially form electromagnets with their magnetic poles facing the axial direction. As a result, a rotating magnetic field is generated between the multiple magnets 39 of the rotor 30 and the teeth 22b, 27b of the stator 20, causing the rotor 30 and the shaft 48 to rotate about the central axis J. In this embodiment, the rotor 30 faces the stator 20 in the axial direction, and therefore, during operation of the motor 10, a magnetic field oriented in the axial direction is generated between the magnets 39 and the stator 20. Therefore, during operation of the motor 10, a magnetic force oriented in the axial direction is applied to each magnet 39. Therefore, during operation of the motor 10, a magnetic force oriented in the axial direction is applied to the rotor 30.

[0052] According to this embodiment, the motor 10 includes a rotor 30 rotatable about a central axis J and a stator 20 facing the rotor 30 at an axial distance. The rotor 30 includes a plurality of magnets 39 arranged circumferentially and a retaining portion 31 that holds the plurality of magnets 39. The retaining portion 31 includes a first retaining portion 32 made of metal and a second retaining portion 40 made of resin that holds the first retaining portion 32 and the plurality of magnets 39. As described above, the weight of the retaining portion 31 can be reduced compared to when the entire retaining portion 31 is made of metal. This reduces the weight of the rotor 30. Furthermore, the axial rigidity of the retaining portion 31 can be increased compared to when the entire retaining portion 31 is made of resin. Therefore, during operation of the motor 10, axial deflection of the rotor 30 due to axially directed magnetic forces acting on the rotor 30 can be suppressed. This prevents fluctuations in the axial spacing between each magnet 39 and the stator 20 during operation of the motor 10, thereby stabilizing the magnetic force applied to each magnet 39. This prevents fluctuations in the output torque of the motor 10, thereby preventing a decrease in the operational stability of the motor 10. Therefore, the rotor 30 can be made lighter while preventing a decrease in the operational stability of the motor 10. Furthermore, as described above, preventing the rotor 30 from bending in the axial direction reduces the air gap between the magnets 39 of the rotor 30 and the teeth 22 b, 27 b of the first stator 21 and the second stator 26. This allows the motor 10 to be made thinner and the output torque of the motor 10 to be increased.

[0053] According to this embodiment, the first retaining portion 32 includes an annular portion 33 disposed radially inward of the second retaining portion 40, and a plurality of protruding portions 35 protruding radially outward from the annular portion 33, at least a portion of which is located inside the second retaining portion 40. Therefore, a portion of each protruding portion 35 is located inside the second retaining portion 40, thereby increasing the contact area between the first retaining portion 32 and the second retaining portion 40. This increases the holding force with which the second retaining portion 40 holds the first retaining portion 32. Therefore, the second retaining portion 40 is effectively prevented from coming off the first retaining portion 32 due to the centrifugal force acting on the second retaining portion 40 when the rotor 30 rotates about the central axis J. This more effectively prevents a decrease in the operational stability of the motor 10.

[0054] According to this embodiment, each of the multiple magnets 39 is disposed radially outward from the annular portion 33, and the protruding portion 35 has a first protruding portion 36 that protrudes radially outward from the annular portion 33. A portion of the first protruding portion 36 is positioned between a pair of circumferentially adjacent magnets 39. This allows the radially outer portion of the metal first protruding portion 36 to be disposed between the pair of magnets 39, thereby increasing the axial rigidity of the radially outer portion of the retaining portion 31. Therefore, during operation of the motor 10, axial deflection of the rotor 30 due to axially directed magnetic forces acting on the rotor 30 can be more effectively suppressed. This more effectively suppresses fluctuations in the axial spacing between each magnet 39 and the stator 20 during operation of the motor 10, thereby more effectively stabilizing the magnetic forces acting on each magnet 39. Therefore, the weight of the rotor 30 can be reduced while more effectively suppressing a decrease in the operational stability of the motor 10.

[0055] According to this embodiment, the radially outer portion of the first protrusion 36 is located inside the second retaining portion 40. As described above, the first protrusion 36 protrudes between a pair of magnets 39 arranged adjacent to each other in the circumferential direction, thereby suitably widening the contact area between the first protrusion 36 and the second retaining portion 40. This makes it possible to more suitably increase the holding force with which the second retaining portion 40 holds the first retaining portion 32. Therefore, it is possible to more suitably prevent the second retaining portion 40 from coming off the first retaining portion 32 when the rotor 30 rotates about the central axis J. Therefore, it is possible to more suitably prevent a decrease in the operational stability of the motor 10.

[0056] According to this embodiment, the axial dimension of the portion of the first protrusion 36 that overlaps with the teeth 22 b, 27 b as viewed in the axial direction is equal to or smaller than the axial dimension Tm of the magnet 39. Therefore, it is easier to widen the axial spacing between the first protrusion 36 and the teeth 22 b, 27 b compared to when the axial dimension of the portion of the first protrusion 36 that overlaps with the teeth 22 b, 27 b as viewed in the axial direction is larger than the axial dimension Tm of the magnet 39. This makes it possible to prevent the first protrusion 36 from coming into contact with the teeth 22 b, 27 b during operation of the motor 10. This more effectively prevents the stability of the operation of the motor 10 from being reduced.

[0057] Furthermore, in this embodiment, as described above, it is easy to widen the axial spacing between the first protrusion 36 and the teeth 22 b, 27 b, and it is easy to narrow the axial spacing between each magnet 39 and the teeth 22 b, 27 b. This makes it possible to increase the magnetic force applied to each magnet 39, thereby increasing the output torque of the motor 10.

[0058] According to this embodiment, the axial dimension of the first protrusion 36 increases radially inward. Therefore, as described above, the axial rigidity of the first protrusion 36 can be increased compared to when the axial dimension of the first protrusion 36 is the same as the axial dimension of the radial outer edge of the first protrusion 36 over the entire radial direction. This more effectively prevents the first protrusion 36 from bending in the axial direction due to the axial magnetic force applied to the rotor 30 during operation of the motor 10. Therefore, the axial distance between the magnet 39 and the stator 20 can be more effectively prevented from fluctuating during operation of the motor 10, thereby more effectively preventing a decrease in the operational stability of the motor 10.

[0059] Furthermore, in this embodiment, as described above, the axial dimension of at least a portion of the first protrusion 36 that does not overlap with the teeth 22 b, 27 b as viewed in the axial direction is greater than the axial dimension Tm of the magnet 39. Therefore, the axial rigidity of the first protrusion 36 can be more effectively increased compared to when the entire axial dimension of the first protrusion 36 is equal to or less than the axial dimension Tm of the magnet 39. This more effectively prevents the first protrusion 36 from bending in the axial direction during operation of the motor 10. Therefore, fluctuations in the axial spacing between each magnet 39 and the stator 20 during operation of the motor 10 can be more effectively prevented, thereby more effectively preventing a decrease in the operational stability of the motor 10.

[0060] According to this embodiment, the multiple protrusions 35 include multiple first protrusions 36 spaced apart from one another along the circumferential direction, with a portion of each of the multiple first protrusions 36 positioned between different pairs of magnets 39. Therefore, because each of the metal first protrusions 36 can be arranged along the circumferential direction, the axial rigidity of the first retaining portion 32 can be increased over the entire circumferential direction. This prevents the rotor 30 from flexing in the axial direction due to axial magnetic forces acting on the rotor 30 during operation of the motor 10 over the entire circumferential direction. Therefore, fluctuations in the axial spacing between each magnet 39 and the stator 20 during operation of the motor 10 can be more effectively prevented. This allows the weight of the rotor 30 to be reduced while more effectively preventing a decrease in the operational stability of the motor 10.

[0061] According to this embodiment, each of the multiple magnets 39 is disposed radially outward from the annular portion 33, and the multiple protrusions 35 include a second protrusion 37 that protrudes radially outward from the annular portion 33. The second protrusion 37 faces the magnet 39 in the radial direction, and at least a portion of the second protrusion 37 is located inside the second retaining portion 40. This preferably widens the contact area between the second protrusion 37 and the second retaining portion 40. This more preferably increases the holding force with which the second retaining portion 40 holds the first retaining portion 32. This more preferably prevents the second retaining portion 40 from coming off the first retaining portion 32 when the rotor 30 rotates about the central axis J. This more preferably prevents a decrease in the operational stability of the motor 10.

[0062] According to this embodiment, the multiple protrusions 35 include multiple second protrusions 37 spaced apart from one another along the circumferential direction, and each of the multiple second protrusions 37 faces a different pair of magnets 39 in the radial direction. Therefore, the metal second protrusions 37 can increase the axial rigidity of the portion of the first retaining portion 32 between the first protrusions 36. This can more effectively increase the axial rigidity of the first retaining portion 32 around the entire circumferential direction. Therefore, during operation of the motor 10, axial deflection of the rotor 30 due to axially directed magnetic forces acting on the rotor 30 can be more effectively suppressed around the entire circumferential direction. This can more effectively suppress fluctuations in the axial spacing between each magnet 39 and the stator 20 during operation of the motor 10. Therefore, the weight of the rotor 30 can be reduced while more effectively suppressing a decrease in the operational stability of the motor 10.

[0063] According to this embodiment, the second protrusions 37 and the first protrusions 36 are arranged alternately in the circumferential direction, and each of the multiple second protrusions 37 is connected to a pair of first protrusions 36 arranged adjacent to each other in the circumferential direction. Therefore, the radially inner portion of each first protrusion 36 and each second protrusion 37 are integrally formed. Therefore, during operation of the motor 10, it is possible to more effectively prevent each of the first protrusions 36 and each of the second protrusions 37 from bending in the axial direction due to the axial magnetic force applied to the rotor 30. Therefore, it is possible to more effectively prevent a decrease in the operational stability of the motor 10.

[0064] According to this embodiment, the axial dimension of the annular portion 33 increases radially inward. Therefore, as described above, the axial rigidity of the annular portion 33 can be increased compared to when the axial dimension of the annular portion 33 is the same as the axial dimension of the radial outer edge of the annular portion 33 over the entire radial direction. This more effectively prevents the annular portion 33 from bending in the axial direction due to the axial magnetic force applied to the rotor 30 during operation of the motor 10. Therefore, the axial spacing between each magnet 39 and the stator 20 can be more effectively prevented from fluctuating during operation of the motor 10, thereby more effectively preventing a decrease in the operational stability of the motor 10.

[0065] According to this embodiment, the second retaining portion 40 is molded by insert molding, using the first retaining portion 32 and the plurality of magnets 39 as insert members. Therefore, as described above, at least a portion of the first retaining portion 32 and the plurality of magnets 39 can be embedded inside the second retaining portion 40. This more effectively increases the holding force with which the second retaining portion 40 holds the first retaining portion 32. This more effectively prevents the second retaining portion 40 from coming off the first retaining portion 32 when the motor 10 is operating. Furthermore, this more effectively increases the holding force with which the second retaining portion 40 holds the magnets 39. This more effectively prevents the magnets 39 from coming off the second retaining portion 40 when the motor 10 is operating. These factors more effectively prevent a decrease in the operational stability of the motor 10.

[0066] In the present embodiment, the protruding portion 35 may not have either the first protruding portion 36 or the second protruding portion 37. In this case, the protruding portion 35 preferably has the first protruding portion 36 that protrudes radially outward more than the second protruding portion 37. Furthermore, the axial dimension of the first protruding portion 36 and the axial dimension of the annular portion 33 may each be the same from the radial outer edge to the radial inner edge.

[0067] 7, a second holding portion 140 of this modification has a pressing portion 144. In the following description, the same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0068] The holding portion 144 has a substantially annular plate shape centered on the central axis J. The radial inner edge of the holding portion 144 faces radially the radial outer edge of the annular portion 33. In this modified example, the radial inner edge of the holding portion 144 contacts the radial inner edge of the annular portion 33. The radial outer edge of the holding portion 144 is located radially outward from the radially inner ends of each magnet 39. The radial outer edge of the holding portion 144 is located radially inward from the tooth portions 22b, 27b. The holding portion 144 has a first holding portion 144a and a second holding portion 144b.

[0069] The first pressing portion 144a is a portion of the second holding portion 140 located above the magnet 39. The radially outer portion of the first pressing portion 144a contacts the upward-facing surface of the portion of the magnet 39 that does not overlap with the teeth 22b, 27b when viewed from the axial direction, i.e., the surface facing the axial direction. The second pressing portion 144b is a portion of the second holding portion 140 located below the magnet 39. The radially outer portion of the second pressing portion 144b contacts the downward-facing surface of the portion of the magnet 39 that does not overlap with the teeth 22b, 27b when viewed from the axial direction, i.e., the surface facing the axial direction. As a result, the pressing portion 144 contacts the axially facing surface of the portion of the magnet 39 that does not overlap with the teeth 22b, 27b when viewed from the axial direction. The other configurations of the rotor 130 and the holding portion 131 of this modified example are similar to the other configurations of the rotor 30 and the holding portion 31 of the above-described embodiment. Other configurations of the motor 110 of this modified example are similar to other configurations of the motor 10 of the above-described embodiment.

[0070] According to this modification, the second holding portion 140 has a pressing portion 144 that contacts the axial surface of the portion of the magnet 39 that does not overlap with the teeth 22 b, 27 b when viewed in the axial direction. Therefore, even if a magnetic force is generated between the magnet 39 and the teeth 22 b, 27 b, the pressing portion 144 can prevent the magnet 39 from falling off the holding portion 131 in the axial direction. This can more effectively prevent the operational stability of the motor 110 from decreasing.

[0071] Furthermore, in this modification, as described above, the retaining portion 144 comes into contact with the axial surface of the magnet 39 at a portion that does not overlap with the teeth 22 b, 27 b when viewed from the axial direction. This prevents the retaining portion 144 from coming into contact with the teeth 22 b, 27 b while the motor 110 is operating. This more effectively prevents the stability of the operation of the motor 110 from decreasing.

[0072] Furthermore, in this modification, as described above, contact between the retainer 144 and the teeth 22 b, 27 b can be prevented during operation of the motor 110, which makes it easier to prevent the gap between the stator 20 and the rotor 130 from increasing. This makes it easier to prevent the axial gap between each magnet 39 and the teeth 22 b, 27 b from increasing. Therefore, a decrease in the magnetic force applied to each magnet 39 can be prevented, and a decrease in the output torque of the motor 110 can be prevented.

[0073] Second Embodiment A rotor 230 included in a motor 210 of this embodiment has an impeller portion 249. In the following description, the same components as those in the first embodiment described above will be denoted by the same reference numerals, and description thereof will be omitted.

[0074] As shown in Fig. 8 , the motor 210 of this embodiment is a disk-shaped motor centered on a central axis J. The motor 210 is a thin motor in which the axial dimension is smaller than the radial dimension. As shown in Fig. 9 , the motor 210 is an axial gap type motor in which the stator 20 and the rotor 230 face each other in the axial direction with a gap between them. The motor 210 includes a case 211, the stator 20, the rotor 230, a shaft 48, and a control unit 270. The motor 210 includes a stator 20 on each axial side of the rotor 230.

[0075] The case 211 has a substantially cylindrical shape centered on the central axis J. The case 211 accommodates the stator 20, the rotor 230, the shaft 48, and the control unit 270 therein. The case 211 also holds the stator 20, the rotor 230, the shaft 48, and the control unit 270. The case 211 has a first case 212, a second case 216, a third case 217, and a side wall hole 215.

[0076] The first case 212 is the upper portion of the case 211. The first case 212 is generally cylindrical and protrudes in the axial direction about the central axis J. The first case 212 is open on the bottom side. The first case 212 has a top wall portion 213 and a first peripheral wall portion 214.

[0077] As shown in Fig. 8, the top wall portion 213 has a generally circular plate shape centered on the central axis J. As shown in Fig. 9, the top wall portion 213 is disposed above the stator 20 and the rotor 230. The top wall portion 213 is provided with a first hole portion 13a, a first bearing holder 13c, a first accommodating hole 13e, and a first through-hole 213g.

[0078] The first through hole 213g is a hole that penetrates the top wall portion 213 in the axial direction. As a result, the case 211 has the first through hole 213g that penetrates the case 211 in the axial direction. The first through hole 213g is provided radially outward from the first bearing holder 13c. The first through hole 213g is provided radially inward from the first accommodating hole 13e. The first through hole 213g is located above the rotor 230 and the stator 20, i.e., on one axial side (+Z side). As shown in FIG. 8 , when viewed from the axial direction, the first through hole 213g has a substantially fan-shaped trapezoid shape centered on the central axis J. The top wall portion 213 is provided with a plurality of first through holes 213g. In this embodiment, the top wall portion 213 is provided with six first through holes 213g. The number of first through holes 213g provided in the top wall portion 213 may be five or less, or seven or more. The first through holes 213g are provided at intervals from one another along the circumferential direction. The inside of the case 211 is connected to the outside of the case 211 via each first through hole 213g. It is noted that the case 211 does not necessarily have to have multiple first through holes 213g.

[0079] 9, the first circumferential wall portion 214 has a generally cylindrical shape that protrudes in the axial direction about the central axis J. The first circumferential wall portion 214 surrounds the stator 20 and the rotor 230 from the radially outer side.

[0080] The second case 216 has a generally circular plate shape centered on the central axis J. The second case 216 is disposed below the control unit 270. The second case 216 is provided with a second through-hole 216e.

[0081] The second through hole 216e is a hole that penetrates the second case 216 in the axial direction. As a result, the case 211 has the second through hole 216e that penetrates the case 211 in the axial direction. When viewed from the axial direction, the second through hole 216e overlaps with the stator 20. The second through hole 216e is located below the rotor 230 and the stator 20, i.e., on the other axial side (-Z side). Although not shown, the second through hole 216e is an elongated hole that extends in the circumferential direction. A plurality of second through holes 216e are provided in the second case 216. In this embodiment, six second through holes 216e are provided in the second case 216. The number of second through holes 216e provided in the second case 216 may be five or less, or seven or more. The second through holes 216e are provided at intervals from one another in the circumferential direction. The inside of the case 211 is connected to the outside of the case 211 via each second through hole 216e. It should be noted that the case 211 does not necessarily have to have multiple second through holes 216e.

[0082] The third case 217 has a generally cylindrical shape that protrudes in the axial direction about the central axis J. The third case 217 is open on the bottom side. A control unit 270 is housed inside the third case 217. The third case 217 is disposed between the first case 212 and the second case 216 in the axial direction. The third case 217 is fixed to both the first case 212 and the second case 216. The third case 217 has an upper wall portion 219 and a second peripheral wall portion 218.

[0083] The upper wall portion 219 has a generally annular plate shape centered on the central axis J. The upper wall portion 219 is disposed below the stator 20 and the rotor 230. The upper wall portion 219 is disposed above the second case 16 and the control unit 270. The upper wall portion 219 is provided with a second bearing holder 219a, a second accommodating hole 219c, and a third through-hole 219e.

[0084] The second bearing holder 219a protrudes upward from the radial inner edge of the upper wall portion 219. The second bearing holder 219a is generally cylindrical and centered on the central axis J. The second bearing holder 219a is open on both axial sides. The second bearing 52 is attached to the inner circumferential surface of the second bearing holder 219a.

[0085] The second accommodating hole 219c is a recess recessed downward from the upward-facing surface of the upper wall portion 219. When viewed in the axial direction, the second accommodating hole 219c has a substantially circular ring shape centered on the central axis J. The second accommodating hole 219c is provided radially outward from the second bearing holder 219a. When viewed in the axial direction, the second accommodating hole 219c overlaps with the first accommodating hole 13e. In this embodiment, the back yoke 27a of the second stator 26 is disposed inside the second accommodating hole 219c. The back yoke 27a is fixed to the inner surface of the second accommodating hole 219c. In this way, the second stator 26 is fixed to the third case 217.

[0086] The second circumferential wall portion 218 has a generally cylindrical shape that protrudes in the axial direction about the central axis J. The second circumferential wall portion 218 protrudes downward from the radial outer edge of the upper wall portion 219. The second circumferential wall portion 218 surrounds the control unit 270 from the radial outside. The upper end of the second circumferential wall portion 218 is fixed to the lower end of the first circumferential wall portion 214. The lower end of the second circumferential wall portion 218 is fixed to the radial outer edge of the second case 216.

[0087] The side wall holes 215 are holes that penetrate the case 211 in the radial direction. The inside of the case 211 is connected to the outside of the case 211 via the side wall holes 215. As shown in Fig. 8 , in this embodiment, the case 211 has a plurality of side wall holes 215. The plurality of side wall holes 215 includes a plurality of first side wall holes 215a, a plurality of second side wall holes 215c, and a plurality of third side wall holes 215e.

[0088] Each of the first side-wall holes 215a is a hole that penetrates the first peripheral wall portion 214 in the radial direction. When viewed in the radial direction, each of the first side-wall holes 215a is an elongated hole that extends in the circumferential direction. In the present embodiment, the multiple side-wall holes 215 include twelve first side-wall holes 215a. The number of first side-wall holes 215a included in the multiple side-wall holes 215 may be eleven or less, or may be thirteen or more. The first side-wall holes 215a are spaced apart from one another in the circumferential direction. As shown in FIG. 9 , each of the first side-wall holes 215a faces the first stator 21 in the radial direction.

[0089] As shown in FIG. 8 , each of the multiple second side-wall holes 215c is a hole that penetrates the first peripheral wall portion 214 in the radial direction. When viewed in the radial direction, each second side-wall hole 215c is an elongated hole that extends in the circumferential direction. Each second side-wall hole 215c is located lower than the first side-wall hole 215a. In this embodiment, the multiple side-wall holes 215 include 12 second side-wall holes 215c. The number of second side-wall holes 215c included in the multiple side-wall holes 215 may be 11 or less, or 13 or more. The second side-wall holes 215c are spaced apart from one another in the circumferential direction. As shown in FIG. 9 , each second side-wall hole 215c faces the second stator 26 in the radial direction.

[0090] As shown in FIG. 8 , each of the multiple third side-wall holes 215e is a hole that radially penetrates the second peripheral wall portion 218. When viewed radially, each third side-wall hole 215e is an elongated hole that extends circumferentially. Each third side-wall hole 215e is located lower than the second side-wall hole 215c. In this embodiment, the multiple side-wall holes 215 include 12 third side-wall holes 215e. The number of third side-wall holes 215e included in the multiple side-wall holes 215 may be 11 or less, or 13 or more. The third side-wall holes 215e are spaced apart from one another in the circumferential direction. As shown in FIG. 9 , each third side-wall hole 215e faces the control unit 270 in the radial direction. Other configurations of the case 211 of this embodiment are similar to those of the case 11 of the first embodiment. The case 211 does not necessarily have to include multiple side-wall holes 215.

[0091] The control unit 270 is disposed inside the third case 217. The control unit 270 generates a current to be supplied to the stator 20 and supplies the current to the stator 20. More specifically, the control unit 270 supplies a current to each of the plurality of coil portions 23 included in the first stator 21 and the plurality of coil portions 28 included in the second stator 26. The control unit 270 has a control board 271.

[0092] The control board 271 has a plate shape that extends in a direction perpendicular to the axial direction. Although not shown, the control board 271 is fixed to the third case 217. Multiple electronic components are mounted on the control board 271. The multiple electronic components include multiple power semiconductor elements such as insulated gate bipolar transistors (IGBTs) and metal-oxide-semiconductor field-effect transistors (MOSFETs), multiple capacitors, and multiple resistors. The control board 271 is electrically connected to an external power supply (not shown) and the stator 20. The control board 271 generates a current of a predetermined waveform from a current supplied by the external power supply and supplies the generated current to the stator 20.

[0093] The rotor 230 has a substantially circular ring shape centered on the central axis J. In the axial direction, the rotor 230 is disposed between the first stator 21 and the second stator 26. The rotor 230 faces each of the first stator 21 and the second stator 26 at an interval in the axial direction. The rotor 230 is rotatable about the central axis J. The rotor 230 has a holding portion 231, a magnet 39, and an impeller portion 249.

[0094] The magnet 39 has a plate shape extending in a direction perpendicular to the axial direction. As shown in FIG. 10 , when viewed from the axial direction, the magnet 39 has a generally trapezoidal shape with its long sides positioned radially outward and its short sides positioned radially inward. In this embodiment, the rotor 230 has a plurality of magnets 39. The magnets 39 are arranged along the circumferential direction. More specifically, the magnets 39 are arranged at approximately equal intervals along the circumferential direction. As shown in FIG. 9 , each magnet 39 is housed inside the holder 231. Each magnet 39 faces the teeth 22b of the first stator 21 in the axial direction. Each magnet 39 faces the teeth 27b of the second stator 26 in the axial direction. When current is supplied from the control unit 270 to each coil portion 23, 28, a magnetic field is generated between each magnet 39 and the teeth 22b, 27b. As a result, a magnetic force directed in the axial direction is applied to each magnet 39. That is, a magnetic force is applied to the rotor 230 in the axial direction.

[0095] The holding portion 231 has a substantially circular ring shape centered on the central axis J. The holding portion 231 holds a plurality of magnets 39. The holding portion 231 has a first holding portion 232 and a second holding portion 240. The second holding portion 240 holds the first holding portion 232.

[0096] 11 , the first holding portion 232 has a substantially circular ring shape centered on the central axis J. The first holding portion 232 is made of metal. In this embodiment, the first holding portion 232 is made of aluminum. The first holding portion 232 has an annular portion 233, a plurality of protrusions 235, an annular wall portion 237, and a convex portion 238.

[0097] The annular portion 233 has a substantially circular ring shape centered on the central axis J. As shown in FIG. 9 , the annular portion 233 is disposed radially inward of the second holding portion 240. The inner circumferential surface of the annular portion 233 is connected to the outer circumferential surface of the shaft 48. In this embodiment, the shaft 48 and the first holding portion 232 are different parts of the same single member. The shaft 48 and the first holding portion 232 may also be different members. In this case, the annular portion 233 is fixed to the outer circumferential surface of the shaft 48.

[0098] As shown in FIG. 11 , each of the multiple protrusions 235 has a plate shape that protrudes radially outward from the annular portion 233. The plate surface of each protrusion 235 faces in a direction tilted from the axial direction to the circumferential direction. More specifically, in this embodiment, the upward surface of each protrusion 235 faces in a direction tilted from the top toward the other circumferential side (-θ side). Furthermore, the downward surface of each protrusion 235 faces in a direction tilted from the bottom toward one circumferential side (+θ side). Alternatively, the upward surface of each protrusion 235 may face in a direction tilted from the top toward one circumferential side, and the downward surface of each protrusion 235 may face in a direction tilted from the bottom toward the other circumferential side. In this embodiment, the first retaining portion 232 has 12 protrusions 235. The number of protrusions 235 included in the first retaining portion 232 may be 11 or less or 13 or more. The protrusions 235 are spaced apart from one another along the circumferential direction. As shown in FIG. 12 , the protrusions 235 are positioned inside the second holding portion 240.

[0099] As shown in Fig. 11 , the annular wall portion 237 has a generally circular ring shape centered on the central axis J. The annular wall portion 237 surrounds each of the multiple protrusions 235 from the radially outer side. The annular wall portion 237 is connected to the radially outer end portions of each of the multiple protrusions 235. As shown in Fig. 12 , the annular wall portion 237 is located inside the second holding portion 240.

[0100] As shown in Fig. 11 , the protrusion 238 is a projection that protrudes radially outward from the annular wall portion 237. In the present embodiment, the protrusion 238 is annular and extends circumferentially along the surface of the annular wall portion 237 that faces radially outward. As shown in Fig. 12 , the protrusion 238 is located inside the second holding portion 240. Note that the first holding portion 232 may have a plurality of protrusions 238 arranged side by side in the circumferential direction.

[0101] As shown in FIG. 9 , the second retaining portion 240 has a substantially circular ring shape centered on the central axis J. The second retaining portion 240 surrounds the annular portion 233 from the radially outer side. In this embodiment, the second retaining portion 240 is made of resin. This allows the weight of the retaining portion 231 to be reduced compared to when the second retaining portion 240 is made of metal, i.e., when the entire retaining portion 231 is made of metal. This therefore allows the weight of the rotor 230 to be reduced. In this embodiment, the second retaining portion 240 is molded by insert molding, using the first retaining portion 232 and the plurality of magnets 39 as insert members. At least a portion of the first retaining portion 232 and the plurality of magnets 39 are embedded inside the second retaining portion 240. As a result, the second retaining portion 240 retains the first retaining portion 232 and the plurality of magnets 39. As shown in FIG. 10 , the second retaining portion 240 has a first portion 241, a plurality of accommodating portions 246, and a second portion 247.

[0102] The first portion 241 is a radially outer portion of the second holding portion 240. The first portion 241 has a generally annular plate shape centered on the central axis J. As shown in Fig. 12, the first portion 241 is provided with a magnet holding hole 241a and a first hole portion 242.

[0103] The magnet holding holes 241a are holes that penetrate the first portion 241 in the axial direction. As shown in FIG. 10 , when viewed axially, the magnet holding holes 241a are generally trapezoidal, with the long sides positioned radially outward and the short sides positioned radially inward. The magnet holding holes 241a are spaced apart from one another in the circumferential direction. Different magnets 39 are disposed inside each magnet holding hole 241a. Each magnet 39 is held on the inner surface of the magnet holding hole 241a. In this way, the second holding portion 240 holds each of the multiple magnets 39. In other words, the holding portion 231 holds each of the multiple magnets 39.

[0104] As shown in Figure 12, the first hole 242 is recessed radially outward from the inner circumferential surface of the first part 241. When viewed in the circumferential direction, the first hole 242 is substantially plus-shaped. An annular wall 237 and a protrusion 238 are disposed inside the first hole 242. The annular wall 237 and the protrusion 238 are each held by the inner surface of the first hole 242. In this way, the second holding part 240 holds the first holding part 232.

[0105] As shown in FIG. 10 , each housing portion 246 is a plate-like member that protrudes radially inward from the radially inward surface of the first portion 241. The upward surface of each housing portion 246 faces in a direction tilted from the top toward the other circumferential side (-θ side). The downward surface of each housing portion 246 faces in a direction tilted from the bottom toward one circumferential side (+θ side). In this embodiment, the second holding portion 240 has twelve housing portions 246. The housing portions 246 are spaced apart from one another in the circumferential direction. As shown in FIG. 12 , each housing portion 246 is provided with a second hole 246a.

[0106] The second holes 246a are holes that penetrate the accommodation portion 246 in the radial direction. A different protrusion 235 is disposed inside each second hole. As a result, each accommodation portion 246 accommodates a different protrusion 235 therein.

[0107] As shown in FIG. 10 , the second portion 247 is generally annular and centered on the central axis J. The second portion 247 is disposed radially inward of each of the accommodating portions 246. The second portion 247 connects to the radially inner ends of each of the accommodating portions 246. As shown in FIG. 12 , the second portion 247 surrounds the annular portion 233 from the radially outer side. The second portion 247 may be in radial contact with the annular portion 233 or may face the annular portion 233 with a radial gap therebetween. The radially inner portions of each of the protrusions 235 extend radially through the second portion 247. Note that the second holding portion 240 may have a pressing portion similar to the second holding portion 140 of the modified example of the first embodiment. This prevents the magnet 39 from falling off the holding portion 231 in the axial direction, thereby effectively preventing a decrease in the operational stability of the motor 210.

[0108] The impeller portion 249 shown in FIG. 10 generates an air flow inside the case 211 when the rotor 330 rotates about the central axis J. The impeller portion 249 has a plurality of blade portions 249a. In this embodiment, the impeller portion 249 has 12 blade portions 249a. The number of blade portions 249a included in the impeller portion 249 may be 11 or less, or 13 or more. The blade portions 249a are spaced apart from one another in the circumferential direction. As shown in FIG. 12, each of the plurality of blade portions 249a includes a protrusion 235 and a housing portion 246. The plate surface of each blade portion 249a faces in a direction inclined circumferentially from the axial direction. Other configurations of the rotor 230 of this embodiment are similar to those of the rotor 30 of the first embodiment described above. Other configurations of the motor 210 of this embodiment are similar to other configurations of the motor 10 of the first embodiment described above.

[0109] When current is sequentially supplied from the control unit 270 to each of the plurality of coil portions 23 of the first stator 21 and the plurality of coil portions 28 of the second stator 26, a rotating magnetic field is generated between the plurality of magnets 39 of the rotor 230 and each of the teeth 22 b, 27 b of the stator 20, as in the first embodiment described above, and the rotor 230 and the shaft 48 rotate about the central axis J. When the motor 210 is operating, a magnetic force directed in the axial direction is applied to each magnet 39. Therefore, when the motor 210 is operating, a magnetic force directed in the axial direction is applied to the rotor 230.

[0110] Next, the airflow generated by the impeller portion 249 and flowing inside the case 211 will be described. When the rotor 230 rotates about the central axis J, the impeller portion 249 also rotates about the central axis J, generating an airflow that flows from below the impeller portion 249 toward above the impeller portion 249. In other words, the impeller portion 249 generates an airflow that flows in the axial direction. Therefore, when the rotor 230 rotates about the central axis J, air outside the case 211 flows into the inside of the case 211 through each of the first side wall holes 215 a, each of the second side wall holes 215 c, each of the third side wall holes 215 e, and each of the second through holes 216 e, as shown in FIG. 13 .

[0111] The airflow AF3 that flows into the case 211 through each of the third side wall holes 215e and each of the second through holes 216e flows into the first case 212 through the third through hole 219e. The airflow AF3 that flows into the first case 212 contacts the second stator 26, passes through the impeller portion 249, and flows upward while contacting the first stator 21. This allows heat generated in each of the first stator 21 and the second stator 26 to be efficiently dissipated to the airflow AF3, thereby efficiently cooling the first stator 21 and the second stator 26. This effectively cools the stator 20. This effectively prevents the temperature of the stator 20 from becoming too high. The airflow AF4 that flows upward due to the impeller portion 249 flows out of the case 211 through each of the first through holes 213g. The airflow AF4 allows the heat generated in the stator 20 to be suitably dissipated to the outside of the motor 210.

[0112] The airflow AF1 that flows into the inside of the case 211 through each first side wall hole 215a flows radially inward between the first stator 21 and the rotor 230 while coming into contact with the first stator 21. This allows heat generated in the first stator 21 to be suitably dissipated into the airflow AF1, thereby more suitably cooling the first stator 21. Therefore, it is possible to more suitably prevent the temperature of the first stator 21 from becoming too high.

[0113] The airflow AF2 that flows into the inside of the case 211 through each second side wall hole 215c flows radially inward between the coil portions 28 of the second stator 26 while coming into contact with the second stator 26. This allows heat generated in the second stator 26 to be efficiently dissipated into the airflow AF2, thereby more efficiently cooling the second stator 26. This more efficiently prevents the temperature of the second stator 26 from becoming too high.

[0114] If the case 211 did not have the multiple side wall holes 215, heat generated in the stator 20 would be dissipated to the airflow AF3 that flows into the inside of the first case 212 through the second through-hole 216e and the third through-hole 219e. Furthermore, the airflow AF4 that flows upward due to the impeller portion 249 flows out of the case 211 through each of the first through-holes 213g. This allows the heat generated in the stator 20 to be suitably dissipated to the outside of the motor 210 by the airflow, thereby suitably cooling the stator 20. Therefore, compared to a case in which the rotor 230 does not have the impeller portion 249, excessively high temperatures of the stator 20 can be effectively prevented.

[0115] Furthermore, when case 211 does not have the plurality of first through holes 213g, the plurality of second through holes 216e, and the plurality of side wall holes 215, impeller portion 249 generates an airflow circulating inside case 211. Therefore, compared to when rotor 230 does not have impeller portion 249, the flow rate of the airflow flowing around stator 20 can be increased, and the amount of heat radiated from stator 20 to the airflow can be increased. The heat radiated to the airflow is transferred to case 211 and radiated to the outside of motor 210 via case 211. Therefore, compared to when rotor 230 does not have impeller portion 249, the amount of heat radiated from stator 20 to the outside of motor 210 can be increased, and an excessive increase in the temperature of stator 20 can be preferably prevented.

[0116] According to this embodiment, the rotor 230 has an impeller portion 249, which has a plurality of blade portions 249a spaced apart from one another in the circumferential direction. Therefore, as described above, when the rotor 230 rotates about the central axis J, the impeller portion 249 can generate an airflow that circulates inside the case 211. This increases the amount of heat dissipated from the stator 20 to the airflow compared to when the rotor 230 does not have the impeller portion 249, thereby effectively preventing the temperature of the stator 20 from becoming too high. Therefore, deterioration of the stator 20 can be effectively prevented.

[0117] According to this embodiment, each of the multiple protrusions 235 has a plate-like shape with a plate surface facing in a direction inclined circumferentially from the axial direction, the second holding portion 240 has multiple housing portions 246 that house different protrusions 235, and each of the multiple blade portions 249a is formed by a protrusion 235 and a housing portion 246. This preferably widens the contact area between the first holding portion 232 and the second holding portion 240. This preferably increases the holding force with which the second holding portion 240 holds the first holding portion 232. This preferably prevents the second holding portion 240 from coming off the first holding portion 232 when the rotor 230 rotates about the central axis J. This preferably prevents a decrease in the operational stability of the motor 210.

[0118] Furthermore, in this embodiment, the impeller portion 249 can be configured using a part of the first holding portion 232 and a part of the second holding portion 240. Therefore, in the rotor 230 of this embodiment, it is not necessary to configure the impeller portion 249 using separate members different from the first holding portion 232 and the second holding portion 240. This makes it possible to prevent an increase in the number of parts of the rotor 230. Therefore, it is possible to prevent an increase in the manufacturing cost and manufacturing man-hours of the motor 210.

[0119] According to this embodiment, the motor 210 includes a case 211 that houses the rotor 230 and the stator 20. The case 211 has a first through hole 213g and a second through hole 216e that are axially aligned. The first through hole 213g is located above the rotor 230 and the stator 20, i.e., on one axial side (+Z side). The second through hole 216e is located below the rotor 230 and the stator 20, i.e., on the other axial side (-Z side). As described above, the plate surfaces of the blades 249a of the impeller portion 249 face in a direction tilted circumferentially from the axial direction. Therefore, as described above, when the rotor 230 rotates about the central axis J, the impeller portion 249 generates an airflow that flows in the axial direction. Therefore, impeller portion 249 easily generates an airflow that flows into case 211 through second through-hole 216e located below rotor 230 and flows out of case 211 through first through-hole 213g located above rotor 230. This increases the flow rate of the airflow flowing around stator 20, thereby favorably increasing the amount of heat radiated from stator 20 to the airflow. This more favorably prevents the temperature of stator 20 from becoming too high, thereby more favorably preventing deterioration of stator 20.

[0120] According to this embodiment, the case 211 has side wall holes 215 that penetrate the case 211 in the radial direction. Therefore, as described above, when the rotor 230 rotates about the central axis J, air can flow into the inside of the case 211 through the side wall holes 215. This increases the flow rate of air flowing into the inside of the case 211, thereby more effectively increasing the amount of heat dissipated from the stator 20 into the airflow. Therefore, it is possible to more effectively prevent the temperature of the stator 20 from becoming too high, and therefore it is possible to more effectively prevent deterioration of the stator 20.

[0121] According to this embodiment, the first holding portion 232 has an annular wall portion 237 that surrounds each of the multiple protrusions 235 from the radially outer side. The annular wall portion 237 is connected to each of the multiple protrusions 235 and is located inside the second holding portion 240. This more preferably increases the contact area between the first holding portion 232 and the second holding portion 240. This more preferably increases the holding force with which the second holding portion 240 holds the first holding portion 232. This more preferably prevents the second holding portion 240 from coming off the first holding portion 232 when the rotor 230 rotates about the central axis J. This more preferably prevents a decrease in the operational stability of the motor 210.

[0122] According to this embodiment, the first retaining portion 232 has a protrusion 238 that protrudes radially outward from the annular wall portion 237, and the protrusion 238 is located inside the second retaining portion 240. This makes it possible to more preferably widen the contact area between the first retaining portion 232 and the second retaining portion 240. This more preferably increases the holding force with which the second retaining portion 240 holds the first retaining portion 232. This more preferably prevents the second retaining portion 240 from coming off the first retaining portion 232 when the rotor 230 rotates about the central axis J. This more preferably prevents a decrease in the operational stability of the motor 210.

[0123] Furthermore, in this embodiment, the protrusions 238 can increase the axial rigidity of the radially outer portion of the retaining portion 231. Therefore, during operation of the motor 210, the rotor 230 can be prevented from bending in the axial direction due to the magnetic force acting in the axial direction on the rotor 230. This can effectively prevent the axial spacing between each magnet 39 and the stator 20 from fluctuating during operation of the motor 210, thereby effectively stabilizing the magnetic force acting on each magnet 39. Therefore, the weight of the rotor 230 can be reduced while effectively preventing a decrease in the operational stability of the motor 210.

[0124] Furthermore, in this embodiment, the retaining portion 231 includes a first retaining portion 232 made of metal and a second retaining portion 240 made of resin that retains the first retaining portion 232 and the plurality of magnets 39. Therefore, as described above, the weight of the rotor 230 can be reduced compared to when the entire retaining portion 231 is made of metal. Furthermore, the axial rigidity of the retaining portion 231 can be increased compared to when the entire retaining portion 231 is made of resin. This more effectively prevents fluctuations in the axial spacing between each magnet 39 and the stator 20 during operation of the motor 210, thereby more effectively preventing a decrease in the operational stability of the motor 210. Therefore, in this embodiment, the weight of the rotor 230 can be reduced while preventing a decrease in the operational stability of the motor 210.

[0125] Third Embodiment A rotor 330 included in a motor 310 of this embodiment has an impeller portion 349. In the following description, the same components as those in the second embodiment described above are denoted by the same reference numerals, and description thereof will be omitted.

[0126] Although not shown, the motor 310 of this embodiment is an axial gap motor in which the stator 20 and the rotor 330 face each other across a gap in the axial direction, similar to the motor 210 of the second embodiment described above. The motor 310 includes a case 211, the stator 20, the rotor 330, a shaft 48, and a control unit 270. The motor 310 includes a stator 20 on each side of the rotor 330 in the axial direction.

[0127] 14 , the rotor 330 has a substantially circular ring shape centered on the central axis J. Although not shown, the rotor 330 is disposed axially between the first stator 21 and the second stator 26. The rotor 330 is rotatable about the central axis J. The rotor 330 has a holder 331, a magnet 39, and an impeller 349.

[0128] The holding portion 331 has a substantially circular ring shape centered on the central axis J. The holding portion 331 holds a plurality of magnets 39. The holding portion 331 has a first holding portion 332 and a second holding portion 340. The second holding portion 340 holds the first holding portion 332.

[0129] 15 , the first holding portion 332 has a substantially circular ring shape centered on the central axis J. The first holding portion 332 is made of metal. In this embodiment, the first holding portion 332 is made of aluminum. The first holding portion 332 has an annular portion 233, a plurality of protrusions 335, an annular wall portion 237, and a convex portion 238.

[0130] Each of the multiple protrusions 335 is rod-shaped and protrudes radially outward from the annular portion 233. The radially outer end of each protrusion 335 is connected to the inner circumferential surface of the annular wall portion 237. This connects the annular wall portion 237 to each of the multiple protrusions 235. The multiple protrusions 335 include multiple first protrusions 335a and multiple second protrusions 335c.

[0131] The first protrusions 335a are spaced apart from one another in the circumferential direction. In the present embodiment, the protrusions 335 include twelve first protrusions 335a. The number of first protrusions 335a included in the protrusions 335 may be eleven or less, or may be thirteen or more. As shown in FIG. 16 , each of the first protrusions 335a is located inside the second holder 340.

[0132] As shown in FIG. 15 , the multiple second protrusions 335c are spaced apart from one another in the circumferential direction. In this embodiment, the multiple protrusions 335 include twelve second protrusions 335c. The number of second protrusions 335c included in the multiple protrusions 335 may be eleven or fewer, or thirteen or more. As shown in FIGS. 15 and 16 , the first protrusions 335a and the second protrusions 335c are alternately arranged in the circumferential direction. Each first protrusion 335a is arranged above each second protrusion 335c, i.e., on one axial side (+Z side). As shown in FIG. 16 , each second protrusion 335c is located inside the second retaining portion 340. Other configurations of the first retaining portion 332 of this embodiment are similar to those of the first retaining portion 232 of the second embodiment described above.

[0133] As shown in FIG. 14 , the second retaining portion 340 has a substantially circular ring shape centered on the central axis J. In this embodiment, the second retaining portion 340 is made of resin. This allows the weight of the retaining portion 331 to be reduced compared to when the second retaining portion 340 is made of metal. Therefore, the weight of the rotor 330 can be reduced. In this embodiment, the second retaining portion 340 is molded by insert molding, using the first retaining portion 332 and the plurality of magnets 39 as insert members. The second retaining portion 340 holds the first retaining portion 332 and the plurality of magnets 39. The second retaining portion 340 has a first portion 241, a plurality of accommodating portions 346, and a second portion 247.

[0134] Each housing portion 346 is plate-shaped and protrudes radially inward from the radially inward surface of the first portion 241. The radially inward end of each housing portion 346 is connected to the second portion 247. The upward surface of each housing portion 346 faces in a direction tilted from the top toward the other circumferential side (-θ side). The downward surface of each housing portion 346 faces in a direction tilted from the bottom toward one circumferential side (+θ side). In this embodiment, the second holding portion 340 has twelve housing portions 346. The housing portions 346 are spaced apart from one another along the circumferential direction. As shown in FIG. 16 , each housing portion 346 houses a pair of first and second protrusions 335 a and 335 c, each different from the other. In this embodiment, each pair of first and second protrusions 335 a and 335 c is embedded in a different housing portion 346. Other configurations of the second holding portion 340 of this embodiment are similar to those of the second holding portion 240 of the second embodiment described above. The second holding portion 340 may have a pressing portion similar to the second holding portion 140 of the modified first embodiment described above. This prevents the magnet 39 from falling off the holding portion 331 in the axial direction, thereby preferably preventing a decrease in the operational stability of the motor 310. Furthermore, the multiple protrusions 335 may further include a protrusion other than the first protrusion 335 a and the second protrusion 335 c, and each housing portion 346 may house the other protrusion in addition to the pair of first protrusion 335 a and second protrusion 335 c.

[0135] The impeller portion 349 shown in FIG. 14 generates an airflow inside the case 211 when the rotor 330 rotates about the central axis J. The impeller portion 349 has a plurality of blades 349a. In this embodiment, the impeller portion 349 has twelve blades 349a. The number of blades 349a included in the impeller portion 349 may be eleven or fewer, or thirteen or more. The blades 349a are spaced apart from one another in the circumferential direction. As shown in FIG. 16, each of the plurality of blades 349a is formed by a pair of first and second protrusions 335a and 335c and a housing portion 346. The plate surface of each blade 349a faces in a direction inclined circumferentially from the axial direction. Other configurations of the rotor 330 of this embodiment are similar to those of the rotor 230 of the second embodiment described above. Other configurations of the motor 310 of this embodiment are similar to other configurations of the motor 210 of the second embodiment described above.

[0136] As in the second embodiment, when the rotor 330 rotates about the central axis J, the impeller portion 349 rotates about the central axis J, generating an airflow that flows from below the impeller portion 349 toward above the impeller portion 349. That is, the impeller portion 349 generates an airflow that flows in the axial direction. Therefore, as the rotor 330 rotates about the central axis J, air outside the case 211 flows into the case 211 through each of the first side-wall holes 215a, each of the second side-wall holes 215c, each of the third side-wall holes 215e, and each of the second through-holes 216e, generating an airflow that flows into the case 211 through each of the first through-holes 213g (see FIG. 13 ). Therefore, as in the second embodiment, this airflow allows heat generated in the stator 20 to be efficiently dissipated to the outside of the motor 310. This makes it possible to preferably prevent the temperature of the stator 20 from becoming too high, and therefore to preferably prevent the stator 20 from deteriorating.

[0137] According to this embodiment, the multiple protrusions 335 include multiple first protrusions 335a arranged at intervals from each other along the circumferential direction, and multiple second protrusions 335c arranged at intervals from each other along the circumferential direction, each of the multiple first protrusions 335a is arranged above the multiple second protrusions 335c, i.e., on one axial side (+Z side), the first protrusions 335a and the second protrusions 335c are arranged alternately in the circumferential direction, the second retaining portion 340 has multiple accommodating portions 346 that accommodate pairs of different first protrusions 335a and second protrusions 335c, and each of the multiple blade portions 349a is composed of a pair of first protrusions 335a and second protrusions 335c and an accommodating portion 346. Therefore, compared to when each blade 349 a is configured with a plate-like protrusion and a housing that houses the protrusion, the volume of the metal material that configures the blade 349 a can be reduced and the volume of the resin material that configures the blade 349 a can be increased. This allows for a reduction in the weight of each blade 349 a, and therefore a reduction in the weight of the rotor 330.

[0138] Furthermore, in this embodiment, the contact area between the multiple protrusions 335 and the second holding portion 340 can be preferably increased. This makes it possible to more preferably increase the holding force with which the second holding portion 340 holds the first holding portion 332. Therefore, it is possible to preferably prevent the second holding portion 340 from coming off the first holding portion 332 when the rotor 330 rotates about the central axis J. Therefore, it is possible to preferably prevent a decrease in the stability of the operation of the motor 310.

[0139] The present invention is not limited to the above-described embodiment, and other configurations and methods may be adopted within the scope of the technical concept of the present invention. For example, the motor may be configured to include only one stator. In this case, the stator may be disposed above or below the rotor, as long as the stator is disposed opposite the rotor with a gap in the axial direction.

[0140] Although the embodiments of the present invention have been described above, the configurations and combinations thereof in the embodiments are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the embodiments.

[0141] The present technology can be configured as follows: (1) A motor including a rotor rotatable about a central axis and a stator facing the rotor at an axial distance, wherein the rotor has a plurality of magnets arranged along a circumferential direction and a holder that holds the plurality of magnets, the holder having a first holder made of metal and a second holder made of resin that holds the first holder and each of the plurality of magnets. (2) The motor described in (1), wherein the first holder has an annular portion arranged radially inward from the second holder, and a plurality of protrusions that protrude radially outward from the annular portion, at least a portion of which is located inside the second holder. (3) The motor described in (2), wherein each of the plurality of magnets is arranged radially outward from the annular portion, and the plurality of protrusions includes a first protrusion that protrudes radially outward from the annular portion, a portion of the first protrusion being located between a pair of the magnets arranged adjacent to each other in the circumferential direction. (4) The motor described in (3), wherein a radially outer portion of the first protrusion is located inside the second holding portion. (5) The motor described in (3) or (4), wherein the stator has a stator core surrounding the central axis, the stator core having an annular back yoke surrounding the central axis and teeth protruding from the back yoke toward the rotor, and wherein an axial dimension of a portion of the first protrusion that overlaps with the teeth as viewed in the axial direction is equal to or less than the axial dimension of the magnet. (6) The motor described in any one of (3) to (5), wherein the axial dimension of the first protrusion increases toward the radially inner side. (7) The motor described in any one of (3) to (6), wherein the multiple protrusions include multiple first protrusions arranged at intervals along the circumferential direction, and a portion of each of the multiple first protrusions is located between different pairs of the magnets. (8) The motor according to any one of (2) to (7), wherein each of the plurality of magnets is disposed radially outward from the annular portion, the plurality of protrusions includes a second protrusion protruding radially outward from the annular portion, the second protrusion facing the magnet in the radial direction, and at least a portion of the second protrusion positioned inside the second holding portion.(9) The motor described in (8), wherein the plurality of protrusions include a plurality of second protrusions arranged at intervals from one another along the circumferential direction, and each of the plurality of second protrusions faces a different pair of the magnets in the radial direction. (10) The motor described in (9), wherein the protrusions have a plurality of first protrusions arranged at intervals from one another along the circumferential direction, the second protrusions and the first protrusions are arranged alternately in the circumferential direction, and each of the plurality of second protrusions is connected to a pair of the first protrusions arranged adjacent to one another in the circumferential direction. (11) The motor described in any one of (2) to (10), wherein the axial dimension of the annular portion increases radially inward. (12) The motor described in (2), wherein the rotor has an impeller portion, and the impeller portion has a plurality of blade portions arranged at intervals from one another along the circumferential direction. (13) The motor described in (12), wherein each of the plurality of protrusions is plate-shaped with a plate surface facing in a direction inclined from the axial direction to the circumferential direction, the second holding portion has a plurality of accommodation portions that accommodate different protrusions, and each of the plurality of blades is constituted by the protrusion and the accommodation portion. (14) The motor described in (12), wherein the plurality of protrusions include a plurality of first protrusions that are arranged at intervals from each other along the circumferential direction and a plurality of second protrusions that are arranged at intervals from each other along the circumferential direction, each of the plurality of first protrusions is arranged on one axial side of the plurality of second protrusions, the first protrusions and the second protrusions are arranged alternately in the circumferential direction, the second holding portion has a plurality of accommodation portions that accommodate a pair of different first protrusions and second protrusions, and each of the plurality of blades is constituted by a pair of the first protrusion and the second protrusion and the accommodation portion. (15) The motor according to any one of (12) to (14), further comprising a case that houses the rotor and the stator, respectively, the case having a first through hole and a second through hole that are axially spaced apart from the rotor and the stator, the first through hole being located on one axial side of the rotor and the stator, and the second through hole being located on the other axial side of the rotor and the stator.(16) The motor according to (15), wherein the case has a side wall hole penetrating the case in the radial direction. (17) The motor according to any one of (12) to (16), wherein the first holding portion has an annular wall portion surrounding each of the plurality of protrusions from the radially outer side, the annular wall portion being connected to each of the plurality of protrusions and being located inside the second holding portion. (18) The motor according to (17), wherein the first holding portion has a convex portion protruding radially outward from the annular wall portion, the convex portion being located inside the second holding portion. (19) The motor according to any one of (1) to (18), wherein the second holding portion is molded by insert molding using the first holding portion and each of the plurality of magnets as insert members. (20) The motor described in any one of (1) to (19), wherein the stator has a stator core surrounding the central axis, the stator core has an annular back yoke surrounding the central axis and teeth protruding from the back yoke toward the rotor, and the second holding portion has a pressing portion that contacts an axial surface of a portion of the magnet that does not overlap with the teeth when viewed in the axial direction.

[0142] 10, 110, 210, 310... Motor, 11, 211... Case, 20... Stator, 30, 130, 230, 330... Rotor, 31, 131, 231, 331... Holding portion, 32, 232, 332... First holding portion, 33, 233... Annular portion, 35, 235, 335... Protruding portion, 36, 335a... First protruding portion, 37, 335c... Second protruding portion projection portion, 39...magnet, 40, 140, 240, 340...second holding portion, 144...pressing portion, 213g...first through hole, 215...side wall hole, 216e...second through hole, 237...annular wall portion, 238...projection portion, 246, 346...accommodation portion, 249, 349...impeller portion, 249a, 349a...blade portion, J...central axis, Tm...axial dimension of magnet

Claims

1. A motor comprising: a rotor rotatable about a central axis; and a stator facing the rotor at an axial distance, wherein the rotor has a plurality of magnets arranged circumferentially and a holding portion that holds the plurality of magnets, and the holding portion has a first holding portion made of metal and a second holding portion made of resin that holds the first holding portion and each of the plurality of magnets.

2. The motor described in claim 1, wherein the first holding portion has: an annular portion arranged radially inward of the second holding portion; and a plurality of protrusions protruding radially outward from the annular portion, at least a portion of which is located inside the second holding portion.

3. The motor described in claim 2, wherein each of the plurality of magnets is arranged radially outward from the annular portion, the plurality of protrusions includes a first protrusion that protrudes radially outward from the annular portion, and a portion of the first protrusion is located between a pair of the magnets that are arranged adjacent to each other in the circumferential direction.

4. The motor according to claim 3, wherein a radially outer portion of said first protrusion is located inside said second holding portion.

5. The motor described in claim 3, wherein the stator has a stator core surrounding the central axis, the stator core has an annular back yoke surrounding the central axis, and teeth protruding from the back yoke toward the rotor, and the axial dimension of the portion of the first protruding portion that overlaps with the teeth when viewed in the axial direction is less than the axial dimension of the magnet.

6. The motor according to claim 3, wherein the axial dimension of said first protrusion increases toward the radially inner side.

7. The motor according to claim 3, wherein the plurality of protrusions include a plurality of first protrusions arranged at intervals along the circumferential direction, and a portion of each of the plurality of first protrusions is located between different pairs of the magnets.

8. The motor described in claim 2, wherein each of the plurality of magnets is arranged radially outward from the annular portion, the plurality of protrusions includes a second protrusion that protrudes radially outward from the annular portion, the second protrusion radially faces the magnet, and at least a portion of the second protrusion is located inside the second holding portion.

9. The motor according to claim 8, wherein the plurality of protrusions include a plurality of second protrusions arranged at intervals from one another along the circumferential direction, and each of the plurality of second protrusions faces a different pair of the magnets in the radial direction.

10. The motor according to claim 9, wherein the protrusions include a plurality of first protrusions arranged at intervals along the circumferential direction, the second protrusions and the first protrusions are arranged alternately in the circumferential direction, and each of the plurality of second protrusions is connected to each of a pair of the first protrusions arranged adjacent to each other in the circumferential direction.

11. The motor according to claim 2, wherein the axial dimension of said annular portion increases radially inward.

12. The motor according to claim 2, wherein the rotor has an impeller portion, and the impeller portion has a plurality of blade portions arranged at intervals along the circumferential direction.

13. A motor as described in claim 12, wherein each of the plurality of protrusions is plate-shaped with the plate surface facing in a direction inclined circumferentially from the axial direction, the second holding portion has a plurality of accommodating portions that accommodate the protrusions that are different from each other, and each of the plurality of blade portions is constituted by the protrusion and the accommodating portion.

14. The motor described in claim 12, wherein the plurality of protrusions include a plurality of first protrusions arranged at intervals from one another along the circumferential direction, and a plurality of second protrusions arranged at intervals from one another along the circumferential direction, each of the plurality of first protrusions is arranged on one axial side of the plurality of second protrusions, the first protrusions and the second protrusions are arranged alternately in the circumferential direction, the second holding portion has a plurality of accommodating portions that accommodate pairs of the first protrusions and the second protrusions that are different from one another, and each of the plurality of blade portions is constituted by a pair of the first protrusions and the second protrusions and the accommodating portion.

15. The motor according to claim 12, further comprising a case that houses the rotor and the stator, respectively, the case having a first through hole and a second through hole that are axially spaced apart, the first through hole being located on one axial side of the rotor and the stator, and the second through hole being located on the other axial side of the rotor and the stator, respectively.

16. The motor of claim 15, wherein the case has a sidewall hole extending radially through the case.

17. The motor described in claim 12, wherein the first holding portion has an annular wall portion that surrounds each of the multiple protrusions from the radially outer side, and the annular wall portion is connected to each of the multiple protrusions and is located inside the second holding portion.

18. The motor according to claim 17, wherein the first holding portion has a protrusion that protrudes radially outward from the annular wall portion, and the protrusion is located inside the second holding portion.

19. A motor according to any one of claims 1 to 18, wherein the second holding portion is formed by insert molding using the first holding portion and each of the plurality of magnets as insert members.

20. A motor as described in any one of claims 1 to 18, wherein the stator has a stator core surrounding the central axis, the stator core has an annular back yoke surrounding the central axis and teeth protruding from the back yoke toward the rotor, and the second holding portion has a pressing portion that contacts the axially facing surface of a portion of the magnet that does not overlap with the teeth when viewed in the axial direction.

Images