Motor

Abstract

A motor according to the present invention comprises: a rotor that can rotate about the central axis; a first stator that is disposed toward one side in the axial direction as compared to the rotor and faces the rotor with a gap therebetween in the axial direction; and a second stator that is disposed toward the other side in the axial direction as compared to the rotor and faces the rotor with a gap therebetween in the axial direction. The position of the first stator relative to the second stator in the circumferential direction is variable.

Description

motor

[0001] This application claims priority to Japanese Patent Application No. 2024-124492, filed on July 31, 2024, the contents of which are incorporated herein by reference.

[0002] An axial gap motor in which a rotor is disposed axially opposite a stator has been disclosed (for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2022-053333

[0004] In general, when a rotor of a motor rotates, an induced voltage is generated in multiple coils attached to the stator. The induced voltage generated in each coil increases as the rotational speed of the rotor increases. Therefore, in the motor described in Patent Document 1, the voltage applied to the coils decreases as the rotational speed of the rotor increases. This limits the range of rotational speed that the rotor can output.

[0005] In view of the above circumstances, one aspect of the present invention has an object to provide a motor that can widen the rotational speed range of the rotor.

[0006] A motor according to one aspect of the present invention includes a rotor rotatable about a central axis, a first stator disposed on one axial side of the rotor and facing the rotor with a gap in the axial direction, and a second stator disposed on the other axial side of the rotor and facing the rotor with a gap in the axial direction, wherein the circumferential position of the first stator relative to the second stator is variable.

[0007] According to one aspect of the present invention, the rotational speed range of the rotor in a motor can be widened.

[0008] FIG. 1 is a cross-sectional view showing a motor according to an embodiment. FIG. 2 is a cross-sectional view showing a stator according to an embodiment, taken along line II-II of FIG. 1. FIG. 3 is a perspective view showing the stator in a first position according to an embodiment. FIG. 4 is a plan view showing the stator in the first position according to an embodiment. FIG. 5 is a perspective view showing the stator in a second position according to an embodiment. FIG. 6 is a plan view showing the stator in the second position according to an embodiment. FIG. 7 is a diagram showing the driving torque of a rotor according to an 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 side of the axial direction toward which the arrow of the Z axis 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 arrow of the Z axis 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] The circumferential direction is indicated by the arrow θ in each drawing. The side of the circumferential direction toward which the arrow θ points is called the "one circumferential side." The opposite side of the circumferential direction to the side toward which the arrow θ points is called the "other circumferential side." The one circumferential side (+θ side) is the side that moves clockwise around the central axis J when viewed from above. The other circumferential side (-θ side) is the side that moves counterclockwise around the central axis J when viewed from above.

[0012] As shown in Figure 1, the motor 10 of this embodiment is a thin motor whose axial dimension is smaller than its radial dimension. The motor 10 is an axial gap motor in which a stator 50 faces a rotor 40 at an axial distance. The motor 10 includes a housing 11, a rotor 40, a shaft 44, a stator 50, a circuit board 70, and an adjustment unit 90. The motor 10 includes a stator 50 on each axial side of the rotor 40.

[0013] The housing 11 has a generally cylindrical shape centered on a central axis J. The housing 11 accommodates the rotor 40, the stator 50, and the circuit board 70 therein. In this embodiment, the housing 11 is made of a metal material such as aluminum. The housing 11 may also be made of a material other than a metal material, such as resin. The housing 11 has a first housing 12, a second housing 15, and a board accommodation portion 18.

[0014] The first housing 12 is the upper portion of the housing 11. The first housing 12 is generally cylindrical and protrudes axially about the central axis J. The first housing 12 is open downward. The first housing 12 has a first peripheral wall 13, a first protrusion 13a, and a top wall 14.

[0015] The first peripheral wall portion 13 has a generally cylindrical shape that protrudes in the axial direction about the central axis J. The first peripheral wall portion 13 surrounds one of the stators 50, which is disposed above the rotor 40, from the radially outer side.

[0016] The first protrusion 13a protrudes downward from the first peripheral wall 13. The first protrusion 13a has a generally cylindrical shape centered on the central axis J. The inner diameter of the first protrusion 13a is larger than the inner diameter of the first peripheral wall 13. A female thread 13c is provided on the inner peripheral surface of the first protrusion 13a.

[0017] The top wall portion 14 is generally disk-shaped and centered on the central axis J. The plate surface of the top wall portion 14 faces the axial direction. The radial outer edge of the top wall portion 14 is connected to the upper end of the first circumferential wall portion 13. The top wall portion 14 is disposed above the rotor 40 and the stator 50. The top wall portion 14 is provided with a first housing portion 14a, a top wall recess 14c, a first holding portion 14e, and a columnar portion 14g.

[0018] The first accommodating portion 14a and the top wall recess 14c are each a recess recessed upward from the downward-facing surface of the top wall portion 14. When viewed in the axial direction, the first accommodating portion 14a has a substantially annular shape centered on the central axis J. When viewed in the axial direction, the top wall recess 14c has a substantially circular shape centered on the central axis J. The top wall recess 14c is provided radially inward of the first accommodating portion 14a.

[0019] The first retaining portion 14e protrudes downward from the radial outer edge of the top wall recess 14c. The first retaining portion 14e is generally cylindrical and centered on the central axis J. A first bearing 78 is attached to the inner peripheral surface of the first retaining portion 14e. The first bearing 78 is generally annular and centered on the central axis J. The first bearing 78 contacts the surface of the top wall recess 14c facing downward in the axial direction. This determines the axial position of the first bearing 78. In this embodiment, the first bearing 78 is a ball bearing. The first bearing 78 may also be a plain bearing.

[0020] The columnar portion 14g protrudes upward from the upward-facing surface of the top wall portion 14. In this embodiment, the columnar portion 14g has a substantially hexagonal columnar shape centered on the central axis J. The columnar portion 14g may have other shapes, such as a cylindrical shape or a square columnar shape.

[0021] The second housing 15 is disposed below the first housing 12. The second housing 15 is generally cylindrical and protrudes axially about the central axis J. The second housing 15 is open on the upper side. The second housing 15 is fixed to the first housing 12. The second housing 15 has a second peripheral wall portion 16, a second protruding portion 16a, and a bottom wall portion 17.

[0022] The second peripheral wall portion 16 has a generally cylindrical shape that protrudes in the axial direction about the central axis J. The second peripheral wall portion 16 surrounds the other stator 50, which is disposed below the rotor 40, from the radially outer side.

[0023] The second protrusion 16a protrudes upward from the second peripheral wall portion 16. The second protrusion 16a is generally cylindrical and centered on the central axis J. The outer diameter of the second protrusion 16a is smaller than the outer diameter of the second peripheral wall portion 16. The second protrusion 16a is positioned radially inward of the first protrusion 13a. The second protrusion 16a faces the first protrusion 13a in the radial direction. An external thread 16c is provided on the outer peripheral surface of the second protrusion 16a. The external thread 16c is threadedly engaged with the internal thread 13c. This allows the first housing 12 to be attached to the second housing 15 so as to be rotatable in the circumferential direction relative to the second housing 15.

[0024] The bottom wall portion 17 has a generally annular plate shape centered on the central axis J. The plate surface of the bottom wall portion 17 faces the axial direction. The bottom wall portion 17 is disposed below the stator 50 and the rotor 40. The bottom wall portion 17 is provided with a second accommodating portion 17a, a bottom wall recess 17c, a first hole 17e, a plurality of second holes 17g, and a second holding portion 17h.

[0025] The second accommodating portion 17a and the bottom wall recess 17c are each recesses recessed downward from the upward-facing surface of the bottom wall portion 17. When viewed in the axial direction, the second accommodating portion 17a has a substantially annular shape centered on the central axis J. When viewed in the axial direction, the second accommodating portion 17a overlaps with the first accommodating portion 14a. When viewed in the axial direction, the bottom wall recess 17c has a substantially circular shape centered on the central axis J. The bottom wall recess 17c is provided radially inward of the second accommodating portion 17a.

[0026] The first hole portion 17e and each of the plurality of second hole portions 17g are holes that penetrate the bottom wall portion 17 in the axial direction. When viewed in the axial direction, the first hole portion 17e has a generally circular shape centered on the central axis J. The first hole portion 17e is provided radially inward from the inner circumferential surface of the bottom wall recess 17c. When viewed in the axial direction, each of the second hole portions 17g has a generally circular shape. Each of the second hole portions 17g is provided radially outward from the second accommodating portion 17a. The second hole portions 17g are provided at intervals along the circumferential direction.

[0027] The second retaining portion 17h protrudes upward from the radial outer edge of the bottom wall recess 17c. The second retaining portion 17h is generally cylindrical and centered on the central axis J. A second bearing 79 is attached to the inner peripheral surface of the second retaining portion 17h. The second bearing 79 is generally annular and centered on the central axis J. The second bearing 79 contacts the surface of the bottom wall recess 17c facing upward in the axial direction. This determines the axial position of the second bearing 79. In this embodiment, the second bearing 79 is a ball bearing. The second bearing 79 may also be a plain bearing.

[0028] The board accommodating portion 18 is disposed below the second housing 15. The board accommodating portion 18 has a generally cylindrical shape that protrudes in the axial direction about the central axis J. The board accommodating portion 18 opens upward. The upper end of the board accommodating portion 18 is fixed to the lower end of the second peripheral wall portion 16. This fixes the board accommodating portion 18 to the second housing 15. The interior of the board accommodating portion 18 is connected to the interior of the first housing 12 and the interior of the second housing 15 via the first hole 17e and each of the second hole portions 17g. The board accommodating portion 18 is provided with a board holding portion 18a and holes 18c.

[0029] The board holding portion 18a has a columnar shape that protrudes upward. In this embodiment, a plurality of board holding portions 18a are provided in the board accommodation portion 18. Each board holding portion 18a holds a circuit board 70.

[0030] The hole portion 18c is a hole that axially penetrates the substrate accommodating portion 18. When viewed from the axial direction, the hole portion 18c has a substantially circular shape centered on the central axis line J. When viewed from the axial direction, the hole portion 18c overlaps with the first hole portion 17e.

[0031] The rotor 40 has a substantially circular ring shape centered on a central axis J. The rotor 40 is rotatable about the central axis J. The rotor 40 faces the stator 50 with a gap therebetween in the axial direction. In the axial direction, the rotor 40 is disposed between one stator 50 and the other stator 50. The rotor 40 has a holder 41 and a magnet 42.

[0032] The holder 41 has a substantially circular ring shape centered on the central axis J. The holder 41 faces the stator 50 with a gap in the axial direction. The radially outer end of the holder 41 is located radially outward of the stator 50. The holder 41 faces the first housing 12 and the second housing 15 with a gap in the radial direction. The holder 41 is provided with a plurality of magnet accommodating portions 41a.

[0033] Each magnet housing portion 41a is a hole that penetrates the holder 41 in the axial direction. The magnet housing portions 41a are provided at intervals along the circumferential direction. Each magnet housing portion 41a faces the stator 50 in the axial direction. In this embodiment, the holder 41 is provided with 40 magnet housing portions 41a. The number of magnet housing portions 41a provided in the holder 41 may be 39 or less, or may be 41 or more.

[0034] In this embodiment, the magnet 42 is composed of a plurality of magnet pieces 42a. In this embodiment, the magnet 42 is composed of 40 magnet pieces 42a. Each magnet piece 42a is housed inside a different magnet housing portion 41a. Each magnet piece 42a is fixed to the inner surface of the magnet housing portion 41a. In this way, the magnet 42 is fixed to the holder 41. The magnet pieces 42a are arranged at intervals along the circumferential direction. Each magnet piece 42a faces the stator 50 in the axial direction. In other words, the magnet 42 faces the stator 50 in the axial direction. Each magnet piece 42a has a magnetic pole whose magnetization direction faces the axial direction. As a result, the magnet 42 has a plurality of magnetic poles whose magnetization direction faces the axial direction. The number of poles of the plurality of magnetic poles of the magnet 42 is 40. In this embodiment, the magnetic poles of magnet pieces 42a arranged adjacent to each other in the circumferential direction are opposite to each other.

[0035] The shaft 44 has a generally cylindrical shape extending in the axial direction around the central axis J. The shaft 44 is disposed radially inward of the rotor 40 and the stator 50. The shaft 44 passes through the holder 41 in the axial direction. The outer peripheral surface of the shaft 44 is fixed to the inner peripheral surface of the holder 41. This allows the shaft 44 to rotate together with the rotor 40 around the central axis J. An upper portion of the shaft 44 is supported by a first bearing 78 so as to be rotatable around the central axis J. A lower portion of the shaft 44 is supported by a second bearing 79 so as to be rotatable around the central axis J. The lower end of the shaft 44 protrudes to the outside of the housing 11 through the first hole 17e and the hole 18c.

[0036] The stator 50 faces the rotor 40 with a gap therebetween in the axial direction. In this embodiment, the motor 10 includes two stators 50. The two stators 50 include a first stator 51 and a second stator 56. That is, the motor 10 includes the first stator 51 and the second stator 56. The magnet 42 faces each of the first stator 51 and the second stator 56 in the axial direction. In this embodiment, the motor 10 is a double-stator, single-rotor axial gap motor.

[0037] The first stator 51 is disposed above the rotor 40, i.e., on one axial side (+Z side). The first stator 51 faces the rotor 40 with an axial gap between them. As shown in FIG. 2 , the first stator 51 has a first stator core 52, an insulator 53, and a first coil portion 54.

[0038] The first stator core 52 is annular and surrounds the central axis J. More specifically, the first stator core 52 is substantially annular and centered on the central axis J. As shown in FIG. 1 , the first stator core 52 has a back yoke 52a and teeth 52c. The back yoke 52a is substantially annular and plate-shaped and centered on the central axis J. The plate surface of the back yoke 52a faces the axial direction. The back yoke 52a is accommodated in the first accommodating portion 14a of the first housing 12. The back yoke 52a is fixed to the inner surface of the first accommodating portion 14a. This fixes the first stator 51 to the first housing 12.

[0039] The teeth 52c are columnar and protrude downward from the back yoke 52a. The teeth 52c face the magnets 42 at an axial distance. This causes the first stator core 52 to face the rotor 40 in the axial direction. As shown in FIG. 2 , the teeth 52c are generally trapezoidal with long sides extending radially. The first stator core 52 has a plurality of teeth 52c. In this embodiment, the first stator core 52 has 36 teeth 52c. The number of teeth 52c included in the first stator core 52 may be 35 or less, or 37 or more. The teeth 52c are arranged at approximately equal intervals along the circumferential direction.

[0040] The insulators 53 insulate the first stator core 52 from the first coil portion 54. The insulators 53 are attached to the first stator core 52. In this embodiment, the first stator 51 has 36 insulators 53. Each insulator 53 is attached to a different tooth portion 52c.

[0041] The first coil portions 54 are attached to the tooth portions 52c via the insulators 53. In this way, the first coil portions 54 are attached to the first stator core 52. The first coil portions 54 are formed by coils wound around the outer peripheral surfaces of the tooth portions 52c. The first stator 51 has a plurality of first coil portions 54. In this embodiment, the first stator 51 has 36 first coil portions 54. Each first coil portion 54 is attached to a different tooth portion 52c. The first coil portions 54 are arranged at intervals from one another in the circumferential direction.

[0042] In the present embodiment, the multiple first coil portions 54 include multiple U-phase coils, multiple V-phase coils, and multiple W-phase coils. That is, in the present embodiment, the number of phases Np of the multiple first coil portions 54 is three. The number of phases Np of the multiple first coil portions 54 is not limited to the number of phases in the present embodiment and may be, for example, six. Currents that are 120° apart from one another in electrical angle are supplied from the circuit board 70 to the U-phase coils, V-phase coils, and W-phase coils. When current is supplied to each first coil portion 54, each first coil portion 54 forms an electromagnet with its magnetic poles facing the axial direction.

[0043] As shown in FIG. 1 , the second stator 56 is disposed below the rotor 40, i.e., on the other axial side (−Z side). The second stator 56 faces the rotor 40 with an axial gap between them. The second stator 56 includes a second stator core 57, a plurality of insulators (not shown), and a second coil portion 59. In this embodiment, the shape and arrangement of each component of the second stator 56 are substantially plane-symmetrical to the shape and arrangement of each component of the first stator 51, with a plane perpendicular to the axial direction as the plane of symmetry. Therefore, in the following description of the second stator 56, description of the same shape, arrangement, and the like as those of the first stator 51 may be omitted.

[0044] The second stator core 57 is annular and surrounds the central axis J. More specifically, the second stator core 57 is substantially annular and centered on the central axis J. The second stator core 57 has a back yoke 57a and teeth 57c. The back yoke 57a is substantially annular and plate-shaped and centered on the central axis J. The back yoke 57a is accommodated in the second accommodating portion 17a of the second housing 15. The back yoke 57a is fixed to the inner surface of the second accommodating portion 17a. This fixes the second stator 56 to the second housing 15.

[0045] The teeth 57c are columnar and protrude upward from the back yoke 57a. The teeth 57c face the magnets 42 at an axial distance. This causes the second stator core 57 to face the rotor 40 in the axial direction. Although not shown, like the teeth 52c described above, the teeth 57c are generally trapezoidal with their long sides extending in the radial direction. The second stator core 57 has 36 teeth 57c. The teeth 57c are arranged at approximately equal intervals in the circumferential direction.

[0046] A plurality of insulators (not shown) insulate the second stator core 57 from the second coil portion 59. Each insulator 53 is attached to a different tooth portion 57c.

[0047] The second coil portions 59 are attached to the tooth portions 57c via insulators (not shown). As a result, the second coil portions 59 are attached to the second stator core 57. The second coil portions 59 are configured by coils wound around the outer peripheral surfaces of the tooth portions 57c. The second stator 56 has a plurality of second coil portions 59. Although not shown, in this embodiment, the second stator 56 has 36 second coil portions 59. Each second coil portion 59 is attached to a different tooth portion 57c. The second coil portions 59 are spaced apart from one another in the circumferential direction. In this embodiment, the second coil portions 59 include a plurality of U-phase coils, a plurality of V-phase coils, and a plurality of W-phase coils. That is, in this embodiment, the number of phases Np2 of the plurality of second coil portions 59 is three. As described above, the number of phases Np of the plurality of first coil portions 54 is three. Therefore, the number of phases Np of the plurality of first coil portions 54 and the number of phases Np2 of the plurality of second coil portions 59 are the same. Thus, the number of phases of the stator 50 in this embodiment is three. Currents that are 120° apart in electrical angle are supplied to the U-phase coils, V-phase coils, and W-phase coils from the circuit board 70. When current is supplied to each second coil portion 59, each second coil portion 59 forms an electromagnet with its magnetic poles facing axially.

[0048] The circuit board 70 has a plate shape that extends in a direction perpendicular to the axial direction. The circuit board 70 is accommodated inside the board accommodating portion 18. The circuit board 70 is held by a plurality of board holding portions 18a. In this way, the circuit board 70 is held in the housing 11. A board hole portion 70a is provided in the circuit board 70. The shaft 44 passes through the board hole portion 70a in the axial direction. Although not shown, the circuit board 70 has an inverter circuit portion composed of a plurality of switching elements, etc. The circuit board 70 is electrically connected to an external power supply (not shown). The inverter circuit portion generates a current to be supplied to the stator 50 from a current supplied by the external power supply.

[0049] The circuit board 70 and the plurality of first coil portions 54 are electrically connected by a plurality of first connection portions 75a. Each of the first connection portions 75a passes axially through the second hole portion 17g. The circuit board 70 supplies current to each of the first coil portions 54 via each of the first connection portions 75a. Each of the first connection portions 75a can electrically connect the circuit board 70 and each of the first coil portions 54 even when the first stator 51 moves relative to the circuit board 70. Each of the first connection portions 75a can be, for example, a cable.

[0050] The circuit board 70 and the second coil portions 59 are electrically connected by a plurality of second connection portions 75c. Each second connection portion 75c passes axially through a second hole portion 17g. The circuit board 70 supplies current to each second coil portion 59 via each second connection portion 75c. A member such as a bus bar can be used as each second connection portion 75c.

[0051] In the present embodiment, the U-phase coil of first coil portion 54 and the U-phase coil of second coil portion 59 are electrically connected via circuit board 70. Similarly, the V-phase coil of first coil portion 54 and the V-phase coil of second coil portion 59, as well as the W-phase coil of first coil portion 54 and the W-phase coil of second coil portion 59, are also electrically connected via circuit board 70. As a result, current is supplied to each of first coil portions 54 and second coil portions 59 from a single inverter included in circuit board 70. Note that each of first coil portions 54 and second coil portions 59 may also be electrically connected via multiple third connection portions (not shown). In this case, current is also supplied to each of first coil portions 54 and second coil portions 59 from a single inverter included in circuit board 70.

[0052] The adjustment unit 90 is capable of rotating the first housing 12 and the first stator 51 around the central axis J. The adjustment unit 90 has a drive unit 91 and a holding unit 92. The drive unit 91 is capable of rotating the holding unit 92 around the central axis J. In this embodiment, the drive unit 91 is a motor. The drive unit 91 is electrically connected to a control unit 95. The control unit 95 controls the operation of the drive unit 91. The control unit 95 is, for example, a computer having a processor such as a CPU (Central Processing Unit).

[0053] The retaining portion 92 has a generally cylindrical shape extending in the axial direction. The retaining portion 92 is connected to the drive portion 91. A retaining hole 92a is provided in the retaining portion 92. The retaining hole 92a is a hole recessed upward from the downward-facing surface of the retaining portion 92. When viewed in the axial direction, the retaining hole 92a has a generally hexagonal shape. The columnar portion 14g of the first housing 12 is inserted into the retaining hole 92a. The inner circumferential surface of the retaining hole 92a and the outer circumferential surface of the columnar portion 14g are fitted together. As described above, the male thread portion 16c of the second housing 15 is threadably fitted with the female thread portion 13c of the first housing 12, thereby attaching the first housing 12 to the second housing 15 so as to be rotatable in the circumferential direction relative to the second housing 15. Therefore, when the drive unit 91 rotates the holding unit 92 about the central axis J, the first housing 12 and the first stator 51 each rotate about the central axis J. This allows the circumferential position of the first stator 51 to be changed relative to the second stator 56. Therefore, in the motor 10 of this embodiment, the circumferential position of the first stator 51 relative to the second stator 56 is variable. In the following description, the circumferential position of the first stator 51 relative to the second stator 56 may be simply referred to as the "relative position." The relative position changes as the first stator 51 rotates about the central axis J. In this embodiment, the relative position is variable between a first position P1 and a second position P2.

[0054] 3 , at first position P1, the circumferential position of first stator 51 relative to second stator 56 is such that the circumferential centers of the plurality of first coil portions 54 are axially opposed to the circumferential centers of the different second coil portions 59. More specifically, the U-phase coils included in the plurality of first coil portions 54 are axially opposed to the U-phase coils included in the plurality of second coil portions 59. The V-phase coils included in the plurality of first coil portions 54 are axially opposed to the V-phase coils included in the plurality of second coil portions 59. The W-phase coils included in the plurality of first coil portions 54 are axially opposed to the W-phase coils included in the plurality of second coil portions 59.

[0055] The first line L1 shown in FIG. 4 is a line passing through the circumferential center of any one of the first coil portions 54a among the multiple first coil portions 54 and the central axis J when viewed from the axial direction. The second line L2 is a line passing through the circumferential center of a second coil portion 59a among the multiple second coil portions 59 that axially faces the first coil portion 54a and the central axis J when viewed from the axial direction. As described above, at the first position P1, the circumferential centers of the first coil portions 54 axially face the circumferential centers of the different second coil portions 59. Therefore, when viewed from the axial direction, the first line L1 and the second line L2 overlap, and the angular difference ΔA between the first line L1 and the second line L2 is 0°. The angular difference ΔA is the circumferential angle between each first coil portion 54 and each second coil portion 59.

[0056] The smaller the angular difference ΔA between the first coil portion 54 and the second coil portion 59, the smaller the amount of circumferential misalignment between the first coil portion 54 and the second coil portion 59. Therefore, the magnetic fields formed by the electromagnets formed by the first coil portion 54 and the second coil portion 59 are combined, increasing the strength of the magnetic field formed by the stator 50. This increases the electromagnetic force applied to the magnets 42 of the rotor 40, allowing the rotor 40 to obtain a large driving torque.

[0057] On the other hand, the smaller the angular difference ΔA, the more the timing at which the induced voltage is generated in the first coil portion 54 and the timing at which the induced voltage is generated in the second coil portion 59 overlap. Furthermore, the induced voltages generated in the first coil portion 54 and the second coil portion 59 increase as the rotational speed of the rotor 40 increases. For these reasons, the smaller the angular difference ΔA, the more significantly the drive torque of the rotor 40 decreases in the high-speed rotation range. Therefore, the smaller the angular difference ΔA, the slower the maximum rotational speed of the rotor 40 tends to be. Therefore, the smaller the angular difference ΔA, the narrower the rotational speed range of the rotor 40 tends to be.

[0058] 5 , at the second position P2, the circumferential position of the first stator 51 relative to the second stator 56 is such that the circumferential center of each of the plurality of first coil portions 54 is circumferentially offset from the circumferential center of the second coil portion 59. In the present embodiment, the adjustment unit 90 rotates the first stator 51 toward the other circumferential side (−θ side) when changing the relative position from the first position P1 to the second position P2. The adjustment unit 90 may also rotate the first stator 51 toward one circumferential side (+θ side) when changing the relative position from the first position P1 to the second position P2.

[0059] As shown in Fig. 6, at the second position P2, the second line L2 is shifted toward the other circumferential side (-θ side) relative to the first line L1. When viewed from the axial direction, the angular difference ΔA between the first line L1 and the second line L2 is 3°. That is, in this embodiment, the rotation angle α, which is the angle by which the first stator 51 rotates when the relative position changes from the first position P1 to the second position P2, is 3°. Note that the rotation angle α may be equal to or less than 3° or equal to or greater than 3°.

[0060] As the angular difference ΔA between the first coil portion 54 and the second coil portion 59 increases, the circumferential misalignment between the first coil portion 54 and the second coil portion 59 increases. This makes it more difficult for the magnetic fields formed by the first coil portion 54 and the second coil portion 59 to combine, thereby reducing the magnetic field strength formed by the stator 50. This reduces the electromagnetic force applied to the magnets 42 of the rotor 40, thereby reducing the drive torque applied to the rotor 40. Therefore, in the low-speed rotation region where induced power is small, the drive torque of the rotor 40 at the second position P2 is smaller than the drive torque of the rotor 40 at the first position P1. That is, in the low-speed rotation region, the drive torque of the rotor 40 at the first position P1 is greater than the drive torque of the rotor 40 at the second position P2. Furthermore, in this embodiment, as described above, the angular difference ΔA at the first position P1 is 0°. Therefore, in the low-speed rotation range of the rotor 40, it is possible to maximize the electromagnetic force applied to the magnets 42 of the rotor 40 at the first position P1. In other words, in the low-speed rotation range of the rotor 40, it is possible to maximize the drive torque of the rotor 40 at the first position P1.

[0061] Furthermore, the larger the angular difference ΔA, the greater the difference between the timing at which induced voltage is generated in the first coil portion 54 and the timing at which induced voltage is generated in the second coil portion 59. As a result, the larger the angular difference ΔA, the more effectively the reduction in drive torque of the rotor 40 can be suppressed in the high-speed rotation range. Therefore, the larger the angular difference ΔA, the faster the maximum rotation speed of the rotor 40. Therefore, the larger the angular difference ΔA, the wider the rotation speed range of the rotor 40 can be.

[0062] That is, by changing the angular difference ΔA, it is possible to change the maximum drive torque and the maximum rotational speed of the rotor 40. More specifically, as the angular difference ΔA increases, the maximum drive torque of the rotor 40 decreases and the maximum rotational speed of the rotor 40 increases.

[0063] As described above, in the motor 10 of this embodiment, the adjustment unit 90 reduces the angular difference ΔA in the low-speed rotation range, thereby increasing the drive torque of the rotor 40 in the low-speed rotation range. Also, the adjustment unit 90 increases the angular difference ΔA in the high-speed rotation range, thereby suppressing a decrease in the drive torque of the rotor 40 in the high-speed rotation range. This increases the maximum rotation speed of the rotor 40, thereby widening the rotational speed range of the rotor 40.

[0064] As described above, in this embodiment, the male thread portion 16c of the second housing 15 shown in FIG. 1 is threadedly engaged with the female thread portion 13c of the first housing 12. Therefore, when the first housing 12 rotates about the central axis J relative to the second housing 15, the axial position of the first housing 12 relative to the second housing 15 changes. In this embodiment, when the first housing 12 rotates toward the other circumferential side (-θ side) relative to the second housing 15, the first housing 12 moves upward. Therefore, when the relative position changes from the first position P1 to the second position P2, the first stator 51 moves upward relative to the rotor 40. The gap G shown in FIG. 1 is the axial gap between the multiple first coil portions 54 and the rotor 40. In this embodiment, the gap G at the second position P2 is larger than the gap G at the first position P1.

[0065] FIG. 7 is a diagram illustrating the drive torque of the motor 10 of this embodiment. The horizontal axis of FIG. 7 represents the number of rotations per minute of the rotor 40, or the rotation speed Vr of the rotor 40. The vertical axis of FIG. 7 represents the drive torque T of the rotor 40. The drive torque shown by the dashed line in FIG. 7 is the first drive torque T1. The first drive torque T1 is the drive torque of the rotor 40 at the first position P1. The drive torque shown by the solid line in FIG. 7 is the second drive torque T2. The second drive torque T2 is the drive torque of the rotor 40 at the second position P2.

[0066] 7, in the rotation speed range lower than the switching speed Vc, the first drive torque T1 is greater than the second drive torque T2. This is because, as described above, the smaller the angular difference ΔA, the greater the combined magnetic field strength of the magnetic fields formed by the first coil portion 54 and the second coil portion 59 at the first position P1, and therefore the greater the electromagnetic force acting on the magnet 42 of the rotor 40 in the rotation speed range where the induced power is small.

[0067] The decrease in the first drive torque T1 relative to the increase in the rotational speed Vr of the rotor 40 is greater than the decrease in the second drive torque T2. Therefore, in a rotational speed range higher than the switching speed Vc, the second drive torque T2 is greater than the first drive torque T1. This is because, as described above, the larger the angular difference ΔA, the greater the difference between the timing at which an induced voltage is generated in the first coil portion 54 and the timing at which an induced voltage is generated in the second coil portion 59, thereby suppressing the decrease in the drive torque of the motor 10 in a high-speed rotational speed range. Therefore, the maximum rotational speed V2 of the rotor 40 at the second position P2 is faster than the maximum rotational speed V1 of the rotor 40 at the first position P1. Therefore, the rotational speed range of the rotor 40 at the second position P2 is wider than the rotational speed range of the rotor 40 at the first position P1.

[0068] In this embodiment, the control unit 95 adjusts the relative position to the first position P1 when the rotational speed Vr of the rotor 40 is less than a predetermined switching speed Vc, and adjusts the relative position to the second position P2 when the rotational speed Vr of the rotor 40 is equal to or greater than the switching speed Vc. This increases the drive torque of the rotor 40 in a low-speed rotation range below the switching speed Vc. It also increases the drive torque of the rotor 40 in a high-speed rotation range above the switching speed Vc, and broadens the rotational speed range of the rotor 40. Furthermore, because the drive torque of the rotor 40 can be increased in both the low-speed rotation range and the high-speed rotation range, the drive efficiency of the motor 10 can be improved.

[0069] According to this embodiment, the motor 10 includes a rotor 40 rotatable about a central axis J, a first stator 51 disposed above the rotor 40, i.e., on one axial side (+Z side), and facing the rotor 40 with a gap in the axial direction, and a second stator 56 disposed below the rotor 40, i.e., on the other axial side (-Z side), and facing the rotor 40 with a gap in the axial direction. The circumferential position of the first stator 51 relative to the second stator 56 is variable. Therefore, by adjusting the circumferential position of the first stator 51 relative to the second stator 56, the angular difference ΔA between the first coil portion 54 and the second coil portion 59 can be adjusted. Therefore, as described above, by reducing the angular difference ΔA in the low-speed rotation range, the drive torque of the rotor 40 in the low-speed rotation range can be increased. Furthermore, by increasing the angular difference ΔA in the high-speed rotation range, the decrease in the drive torque of the rotor 40 in the high-speed rotation range can be suppressed, thereby increasing the maximum rotation speed of the rotor 40. This makes it possible to widen the rotational speed range of the rotor 40. Therefore, by adjusting the angular difference ΔA in accordance with the rotational speed Vr of the rotor 40, it is possible to increase the drive torque of the rotor 40 in both the low-speed rotation range and the high-speed rotation range. Therefore, it is possible to widen the rotational speed range of the rotor 40 and to increase the drive efficiency of the motor 10.

[0070] According to this embodiment, the first stator 51 includes a first stator core 52 surrounding the central axis J and a plurality of first coil portions 54 attached to the first stator core 52 and spaced apart from one another along the circumferential direction, while the second stator 56 includes a second stator core 57 surrounding the central axis J and a plurality of second coil portions 59 attached to the second stator core 57 and spaced apart from one another along the circumferential direction, and the relative positions of the first coil portions 54 are variable between a first position P1 where the circumferential centers of the first coil portions 54 are axially opposed to the circumferential centers of the second coil portions 59, which are different from one another, and a second position P2 where the circumferential centers of the first coil portions 54 are circumferentially shifted from the circumferential centers of the second coil portions 59. Therefore, at the first position P1, the angular difference ΔA is 0°, and therefore, as described above, the electromagnetic force applied to the magnets 42 of the rotor 40 can be maximized in the low-speed rotation range. This maximizes the drive torque of the rotor 40 in the low-speed rotation range. Furthermore, since the angular difference ΔA can be provided at the second position P2, the decrease in drive torque of the rotor 40 in the high-speed rotation range can be suppressed compared to the first position P1. By appropriately adjusting the relative position between the first position P1 and the second position P2 according to the rotation speed Vr of the rotor 40, the drive torque of the rotor 40 can be more suitably increased in both the low-speed rotation range and the high-speed rotation range. This allows the rotation speed range of the rotor 40 to be widened, and the drive efficiency of the motor 10 to be more suitably improved.

[0071] According to this embodiment, the axial distance G between the rotor 40 and the plurality of first coil portions 54 at the second position P2 is larger than the axial distance G between the rotor 40 and the plurality of first coil portions 54 at the first position P1. Therefore, the axial distance between the magnet 42 and each of the first coil portions 54 at the second position P2 can be increased. Therefore, the induced voltage generated in each of the first coil portions 54 at the second position P2 can be suitably reduced. This makes it possible to more suitably suppress a decrease in the drive torque of the rotor 40 in the high-speed rotation range at the second position P2. Therefore, the rotational speed range of the rotor 40 can be more suitably widened, and the drive efficiency of the motor 10 can be more suitably improved.

[0072] According to this embodiment, the motor 10 includes an adjustment unit 90 that can rotate the first stator 51 about the central axis J. The adjustment unit 90 adjusts the relative position to a first position P1 when the rotational speed Vr of the rotor 40 is less than a predetermined switching speed Vc, and adjusts the relative position to a second position P2 when the rotational speed Vr of the rotor 40 is equal to or greater than the switching speed Vc. Therefore, by reducing the angular difference ΔA in the low-speed rotation range below the switching speed Vc, the drive torque of the rotor 40 can be increased. Furthermore, by increasing the angular difference ΔA in the high-speed rotation range above the switching speed Vc, a decrease in the drive torque of the rotor 40 can be suppressed. This allows the rotational speed range of the rotor 40 to be more appropriately widened, and the drive efficiency of the motor 10 to be more appropriately improved.

[0073] 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 angular difference at the first position may be smaller than the angular difference at the second position, and the angular difference at the first position does not have to be 0°. In this case, at the first position, the circumferential center of each of the multiple first coil sections is arranged to be circumferentially offset from the circumferential center of the second coil section.

[0074] 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.

[0075] The present technology can be configured as follows: (1) A motor including: a rotor rotatable about a central axis, a first stator disposed on one axial side of the rotor and facing the rotor with an axial gap therebetween, and a second stator disposed on the other axial side of the rotor and facing the rotor with an axial gap therebetween, wherein the relative position of the first stator in the circumferential direction with respect to the second stator is variable. (2) The motor according to (1), wherein the first stator has a first stator core surrounding the central axis and a plurality of first coil portions attached to the first stator core and spaced apart along the circumferential direction, the second stator has a second stator core surrounding the central axis and a plurality of second coil portions attached to the second stator core and spaced apart along the circumferential direction, and the relative positions are variable between a first position in which the circumferential centers of the plurality of first coil portions are axially opposed to circumferential centers of the different second coil portions, and a second position in which the circumferential centers of the plurality of first coil portions are circumferentially shifted from the circumferential centers of the second coil portions. (3) The motor according to (2), wherein the axial spacing between the plurality of first coil portions and the rotor at the second position is larger than the axial spacing between the plurality of first coil portions and the rotor at the first position. (4) The motor according to (2) or (3), further comprising an adjustment unit capable of rotating the first stator around the central axis, wherein the adjustment unit adjusts the relative position to the first position when the rotation speed of the rotor is less than a predetermined switching speed, and adjusts the relative position to the second position when the rotation speed of the rotor is equal to or greater than the switching speed.

[0076] 10...motor, 40...rotor, 51...first stator, 52...first stator core, 54...first coil portion, 56...second stator, 57...second stator core, 59...second coil portion, 90...adjustment portion, G...axial distance between multiple first coil portions and rotor, J...central axis, P1...first position, P2...second position, Vc...switching speed, Vr...rotor rotation speed

Claims

1. A motor comprising: a rotor rotatable about a central axis; a first stator arranged on one axial side of the rotor and facing the rotor with an axial gap; and a second stator arranged on the other axial side of the rotor and facing the rotor with an axial gap, wherein the circumferential position of the first stator relative to the second stator is variable.

2. The motor described in claim 1, wherein the first stator has a first stator core surrounding the central axis and a plurality of first coil sections attached to the first stator core and spaced apart from one another along the circumferential direction, and the second stator has a second stator core surrounding the central axis and a plurality of second coil sections attached to the second stator core and spaced apart from one another along the circumferential direction, and the relative positions are variable between a first position in which the circumferential centers of the plurality of first coil sections face axially opposite circumferential centers of different second coil sections, and a second position in which the circumferential centers of the plurality of first coil sections are circumferentially shifted from the circumferential centers of the second coil sections.

3. The motor according to claim 2, wherein the axial spacing between the plurality of first coil portions and the rotor at the second position is greater than the axial spacing between the plurality of first coil portions and the rotor at the first position.

4. The motor according to claim 2 or 3, further comprising an adjustment unit capable of rotating the first stator around the central axis, wherein the adjustment unit adjusts the relative position to the first position when the rotational speed of the rotor is less than a predetermined switching speed, and adjusts the relative position to the second position when the rotational speed of the rotor is equal to or greater than the switching speed.

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