Axial gap motor, robot, and robot system

Abstract

The invention provides an axial gap motor, a robot and a robot system. The outer diameter size of the axial gap motor is reduced. The first motor (101) and the second motor (201) have: rotors (120, 220) that rotate about a rotation axis (AX3); a stator (110, 210) facing the rotor (120, 220) in the direction of the rotation axis (AX3); a back yoke section (403) provided to the stators (110, 210); a plurality of teeth (407) protruding from the back yoke (403) toward one side in the direction of the rotation axis (AX3); a plurality of coils (405) attached to the plurality of teeth (407); and a wiring substrate (413) which is disposed on the other side in the direction of the rotation axis (AX3) with respect to the back yoke part (403) and to which a plurality of lead wires (411) led out from the plurality of coils (405) are connected.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to axial-gap motors, robots, and robot systems. Background Art

[0002] Patent Document 1 discloses an axial-gap type motor including: a rotor fixed to a rotating shaft; and a first stator and a second stator disposed on opposite sides in the axial direction of the rotor with a gap therebetween. In this axial-gap type motor, the first stator and the second stator each have a back yoke, teeth provided on the rotor side of the back yoke in the axial direction, and coils wound around the teeth, and a wiring board for performing wiring on the neutral point side and the power supply side of the coils is disposed on the outer side in the radial direction with respect to the teeth.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2008-172859 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In the above prior art, since the wiring board is disposed on the outer side in the radial direction with respect to the teeth, there is a problem that the outer diameter of the motor increases.

[0008] The present invention has been made in view of such problems, and an object thereof is to provide an axial-gap motor, a robot, and a robot system capable of reducing the outer diameter size.

[0009] Means for Solving the Problems

[0010] To solve the above problems, according to one aspect of the present invention, an axial-gap motor is provided, which includes: a rotor that rotates about a rotation axis; a stator that faces the rotor in the direction of the rotation axis; a first back yoke provided on either the rotor or the stator; a plurality of teeth protruding from the first back yoke toward one side in the direction of the rotation axis; a plurality of coils mounted on the plurality of teeth; and a wiring portion disposed on the other side in the direction of the rotation axis with respect to the first back yoke and connecting a plurality of lead wires led out from the plurality of coils.

[0011] Further, according to another aspect of the present invention, a robot is applied, which is provided with an axial clearance motor at a joint portion. The axial clearance motor has: a rotor that rotates about a rotation axis; a stator that faces the rotor in the direction of the rotation axis; a first back yoke that is provided on either the rotor or the stator; a plurality of teeth that project from the first back yoke toward one side in the direction of the rotation axis; a plurality of coils that are mounted on the plurality of teeth; and a wiring portion that is disposed on the other side in the direction of the rotation axis with respect to the first back yoke and connects a plurality of lead wires led out from the plurality of coils.

[0012] Further, according to another aspect of the present invention, a robot system is applied, which includes the robot and a control device that controls the operation of the robot.

[0013] Advantageous Effects of the Invention

[0014] According to the axial clearance motor and the like of the present invention, the outer diameter dimension can be miniaturized. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 FIG. is an example showing an overall structure of a robot system according to an embodiment.

[0016] Figure 2 FIG. is a perspective view showing an example of an external structure of a first motor unit and a second motor unit provided at a distal end portion of a second arm.

[0017] Figure 3 FIG. is an exploded perspective view showing an example of an internal structure of the first motor unit.

[0018] Figure 4 FIG. is an exploded perspective view showing an example of an internal structure of the second motor unit.

[0019] Figure 5 FIG. is a cross-sectional view schematically showing an example of an internal structure of the first motor unit and the second motor unit.

[0020] Figure 6 FIG. is a perspective view showing an example of an overall structure of a rotor.

[0021] Figure 7 FIG. is a plan view showing an example of the overall structure of the rotor as viewed from the stator side in the axial direction.

[0022] Figure 8 FIG. is a plan view showing an example of a shape of a magnet included in the rotor.

[0023] Figure 9 FIG. is a plan view showing an example of a manner of cutting out a plurality of magnets included in the rotor from a magnet sheet.

[0024] Figure 10 It is a diagram showing an example of the relationship between cogging torque and the coefficient of the offset angle of the magnet.

[0025] Figure 11 It is a perspective view observed from the coil side showing an example of the overall structure of the stator.

[0026] Figure 12 It is a perspective view observed from the wiring board side showing an example of the overall structure of the stator.

[0027] Figure 13 It is a cross-sectional view showing an example of the overall structure of the stator.

[0028] Figure 14 It is a perspective view showing an example of the structure of the bobbin included in the stator.

[0029] Figure 15 It is a plan view showing an example of the arrangement of the magnets of the rotor of the embodiment.

[0030] Figure 16 It is a plan view showing an example of the arrangement of the magnets of the rotor of a modified example in which the magnet is not skewed.

[0031] Figure 17 It is a plan view showing an example of the arrangement of the magnets of the rotor of a modified example in which the outer and inner edges in the radial direction of the magnet are arc-shaped.

[0032] Figure 18 It is a plan view showing an example of the arrangement of the magnets of the rotor of a modified example in which the outer and inner edges in the radial direction of the magnet are arc-shaped and the magnet is not skewed.

[0033] Reference Numeral Explanation

[0034] 1: Robot system

[0035] 10: Transfer robot (an example of a robot)

[0036] 20: Control device

[0037] 101: First motor (an example of an axial-gap motor)

[0038] 110: Stator

[0039] 120: Rotor

[0040] 201: Second motor (an example of an axial-gap motor)

[0041] 210: Stator

[0042] 220: Rotor

[0043] 300: Rotor core

[0044] 303: Back yoke part (an example of the second back yoke)

[0045] 303A: Back yoke part

[0046] 303B: Back yoke part

[0047] 305: Magnet

[0048] 305a: One side

[0049] 305A: Magnet

[0050] 305b: The other side

[0051] 305B: Magnet

[0052] 305c: Outer side

[0053] 305d: Inner side

[0054] 307: First magnet

[0055] 307A: First magnet

[0056] 307B: First magnet

[0057] 309: Second magnet

[0058] 309A: Second magnet

[0059] 309B: Second magnet

[0060] 400: Stator core

[0061] 401: Opening part

[0062] 401a: Inner peripheral surface

[0063] 401b: Groove part

[0064] 403: Back yoke part (an example of the first back yoke)

[0065] 404: Outer peripheral protrusion

[0066] 405: Coil

[0067] 407: Tooth

[0068] 409: Bobbin

[0069] 409A: Bobbin

[0070] 409B: Bobbin

[0071] 411: Lead wire

[0072] 411a: Wire

[0073] 411b: Wire

[0074] 413: Wiring Substrate (An Example of a Wiring Portion)

[0075] 415: Concave Portion

[0076] 419: Protrusion Portion (An Example of an Insulating Portion)

[0077] 419a: Protrusion Portion

[0078] 419b: Protrusion Portion

[0079] 423: End Face

[0080] AX3: Axis of Rotation

[0081] DR: Radial Direction

[0082] J3: Joint Portion

[0083] LCM: Least Common Multiple

[0084] S1: Gap Shape

[0085] S2: Gap Shape

[0086] θ1: Offset Angle (An Example of the First Angle)

[0087] θ2: Skew Angle (An Example of the Second Angle) Detailed Embodiment

[0088] Hereinafter, the embodiments will be described with reference to the drawings. In the embodiments, for the sake of convenience in explaining the structure of a robot or the like, a three-dimensional rectangular coordinate system of the X-axis, Y-axis, and Z-axis is sometimes appropriately used. The Z-axis is in the vertically upward positive direction, the X-axis is along the extending direction of the arm that supports the hand, with the end side that supports the hand being the positive direction, and the Y-axis is orthogonal to the X-axis and the Z-axis.

[0089] <1. Overall Structure of the Robot System>

[0090] Refer to Figure 1 , and an example of the overall structure of the robot system 1 of the embodiment will be described. Figure 1 is a diagram showing an example of the overall structure of the robot system 1 of the embodiment.

[0091] As Figure 1As shown, the robot system 1 has a transfer robot 10 and a control device 20 that controls the operation of the robot 10. The transfer robot 10 (an example of a robot) includes a main body portion 15 provided on the ground or the like and a lifting portion 16 that moves up and down with respect to the main body portion 15. The lifting portion 16 moves the first arm 11 and the second arm 12, which are horizontal multi-joint type arms, up and down. At the end side of the second arm 12, for example, two end effectors 13A and 13B are provided. The end effectors 13A and 13B can each hold an object to be transferred, such as a substrate for semiconductors. The transfer robot 10 includes, for example, three joint portions J1, J2, and J3. At the joint portion J1, the first arm 11 rotates around the rotation axis AX1 of the motor with respect to the lifting portion 16. At the joint portion J2, the second arm 12 rotates around the rotation axis AX2 of the motor with respect to the end portion of the first arm 11. At the joint portion J3, the end effectors 13A and 13B rotate coaxially around the rotation axis AX3 of the motor. The rotation axes AX1, AX2, and AX3 are substantially parallel to the Z axis.

[0092] In addition, Figure 1 shows two end effectors 13A and 13B, but the number of end effectors can also be three or more. Also, Figure 1 shows a horizontal multi-joint type arm composed of two arms (the first arm 11 and the second arm 12), but the number of arms can also be one, or three or more.

[0093] The control device 20 is connected to the transfer robot 10. The control device 20 includes a control unit 21 and a storage unit 22. The control unit 21 includes an operation control unit 21a. In addition, the storage unit 22 stores teaching data 22a.

[0094] The operation control unit 21a controls the operation of the transfer robot 10 based on the teaching data 22a. As an example, the operation control unit 21a instructs the motors corresponding to the respective axes in the transfer robot 10 based on the teaching data 22a stored in the storage unit 22, thereby causing the transfer robot 10 to transfer an object to be transferred, such as a substrate. The operation control unit 21a performs feedback control using the detection values of the encoders in the motors. The operation control unit 21a can also perform processing to stop or decelerate the operation of the transfer robot 10 when an error occurs in the operation of the transfer robot 10 or the like.

[0095] The teaching data 22a is generated by teaching the operation to the transfer robot 10. The teaching data 22a is information that defines the operation of the transfer robot 10, such as the movement trajectory of the end effector. In addition, the teaching data 22a generated by another computer connected by a wired or wireless network can also be stored in the storage unit 22.

[0096] <2. Structure of the motor unit>

[0097] Refer to Figures 2 to 5, showing an example of the structure of the motor unit for driving the hand provided at the joint portion J3 of the transfer robot 10. Figure 2 It is a perspective view showing an example of the external structure of the first motor unit and the second motor unit provided at the end portion of the second arm. Figure 3 It is an exploded perspective view showing an example of the internal structure of the first motor unit, Figure 4 It is an exploded perspective view showing an example of the internal structure of the second motor unit. Figure 5 It is a cross-sectional view schematically showing an example of the internal structure of the first motor unit and the second motor unit. In addition, Figure 5 It is a cross-sectional view obtained by cutting in a plane parallel to the YZ plane at the position of the rotation axis AX3 when observing the base end side from the end side of the second arm 12.

[0098] As Figure 2 shown, the first motor unit 100 and the second motor unit 200 for respectively driving the two hands 13A and 13B are provided at the end side of the base frame 12A of the second arm 12. The first motor unit 100 and the second motor unit 200 are overlapped and arranged in the direction along the rotation axis AX3. In the example shown in Figure 2 , the first motor unit 100 is arranged above the second motor unit 200. The first motor unit 100 includes a sub-frame 12S1 and a first motor 101 built in the sub-frame 12S1. The second motor unit 200 includes a sub-frame 12S2 and a second motor 201 built in the sub-frame 12S2. The base frame 12A and the sub-frames 12S1 and 12S2 constitute the housing of the second arm 12. In addition, in Figure 2 , the base frame 12A is shown by a one-dot chain line.

[0099] The first motor 101 and the second motor 201 are arranged in a posture where they are aligned in the direction along the rotation axis AX3 with the rotation axis AX3 as a common axis. The first motor 101 drives the hand 13A, and the second motor 201 drives the hand 13B. The first motor 101 and the second motor 201 are so-called axial-gap motors in which the rotor and the stator face each other in the direction along the rotation axis AX3. The first motor 101 and the second motor 201 directly drive the hands 13A and 13B respectively.

[0100] The first motor 101 and the second motor 201 are so-called hollow motors provided with a hollow portion penetrating along the rotation axis AX3. The first motor 101 includes a hollow shaft 102, and the second motor 201 includes a hollow shaft 202. The hollow shaft 102 is connected to the rotor 120 of the first motor 101 (refer to Figure 3 , Figure 5 ), and the hollow shaft 202 is connected to the rotor 220 of the second motor 201 (refer to Figure 4 ,Figure 5 ) Connection. The hollow shafts 102 and 202 extend along the rotation axis AX3 and rotate about the rotation axis AX3.

[0101] As Figure 2 shown, the hollow shaft 102 of the first motor 101 protrudes toward the upper surface side of the sub-frame 12S1 of the first motor unit 100. The hollow shaft 202 of the second motor 201 is inserted through the hollow shaft 102 of the first motor 101, passes through the first motor unit 100, and protrudes toward the upper surface side of the sub-frame 12S1. The hand 13A is connected to the hollow shaft 102, and the hand 13B is connected to the hollow shaft 202. The inner hollow shaft 202 rotates the upper hand 13B, and the outer hollow shaft 102 rotates the lower hand 13A.

[0102] In addition, when the number of hands is three or more, motor units having the same number as the hands may be provided.

[0103] As Figure 3 shown, the first motor unit 100 includes a first motor 101 and a sub-frame 12S1. In addition, in Figure 3 , illustrations of a cover that is attached and detached to the upper surface of the sub-frame 12S1, a communication hole provided on the side surface of the sub-frame 12S1 on the side connected to the base frame 12A for inserting and passing through the cable 103 (see Figure 2 ), and an inner wall of the sub-frame 12S1 on which each component of the first motor 101 is mounted are omitted.

[0104] The first motor 101 (an example of an axial clearance motor) includes a rotor 120 that rotates about the rotation axis AX3 and a stator 110 that faces the rotor 120 in the direction of the rotation axis AX3. The first motor 101 has a shaft portion 102a and a shaft hub portion 102b that form the Figure 2 shown hollow shaft 102, a bearing 140, and a bearing pressing member 141. The first motor 101 includes an encoder 130. The encoder 130 includes a disk portion 131, a detection portion 132, and a support portion 133.

[0105] The stator 110 is a disk shape having a hollow portion along the rotation axis AX3, and has teeth on the end surface on the side closer to the rotor 120 and coils wound around the teeth. In addition, the detailed structure of the stator 110 will be described later. The rotor 120 is a disk shape having a hollow portion along the rotation axis AX3 that communicates with the hollow portion of the stator 110, and has a plurality of magnets provided along the circumferential direction on the end surface on the side closer to the stator 110. In addition, the detailed structure of the rotor 120 will be described later. The disk portion 131 of the encoder 130 is fixed to the end surface of the rotor 120 on the side opposite to the stator 110. The disk portion 131 also has a hollow portion that communicates with the hollow portion of the rotor 120.

[0106] The shaft portion 102a of the hollow shaft 102 is fixed to the upper surface of the rotor 120. The stator 110 is arranged in such a manner that its inner circumference is separated from the outer circumference of the shaft portion 102a. The bearing 140 is a so-called crossed roller bearing. The inner circumferential side of the bearing 140 is fixed to the outer circumference of the hub portion 102b of the hollow shaft 102, and the outer circumferential side of the bearing 140 is fixed to the sub-frame 12S1 by the bearing pressing member 141. In addition, in Figure 3 the illustration of the inner wall of the sub-frame 12S1 that fixes the bearing 140 is omitted. The hub portion 102b of the hollow shaft 102 is fixed to the upper surface of the shaft portion 102a in such a manner that the hollow portion communicates with the hollow portion of the shaft portion 102a.

[0107] The detection portion 132 of the encoder 130 is arranged to face the disk portion 131 provided on the end face of the rotor 120. The support portion 133 supports the end face side of the detection portion 132 opposite to the disk portion 131 and is fixed to the sub-frame 12S1. In addition, the support portion 133 may be formed in a shape that can be fixed to the stator 110 and fixed to the stator 110.

[0108] As Figure 4 shown, the second motor unit 200 includes a second motor 201 and a sub-frame 12S2. In addition, in Figure 4 the illustration of the communication hole provided on the side surface of the sub-frame 12S2 connected to the base frame 12A and used for passing and inserting the cable 203 (refer to Figure 2 ) and the inner wall of the sub-frame 12S2 provided inside and mounting the components of the second motor 201 is omitted.

[0109] The second motor 201 (an example of an axial gap motor) includes a rotor 220 that rotates about the rotation axis AX3 and a stator 210 that faces the rotor 220 in the direction of the rotation axis AX3. The second motor 201 includes Figure 2 the hollow shaft 202, the bearing 240, the outer circumferential pressing member 241, and the inner circumferential pressing member 242 shown. The outer circumferential pressing member 241 is a member that presses the outer circumference of the bearing 240, and the inner circumferential pressing member 242 is a member that presses the inner circumference of the bearing 240. The second motor 201 includes an encoder 230. The encoder 230 includes a disk portion 231, a detection portion 232, and a support portion 233.

[0110] The stator 210 is in the shape of a circular plate with a hollow portion along the rotation axis AX3, and has teeth on the end face on the side closer to the rotor 220 and coils wound around the teeth. The detailed structure of the stator 210 will be described later. The rotor 220 is in the shape of a circular plate with a hollow portion along the rotation axis AX3 that communicates with the hollow portion of the stator 210, and has a plurality of magnets provided along the circumferential direction on the end face on the side closer to the stator 210. The detailed structure of the rotor 220 will be described later. A disk portion 231 of the encoder 230 is fixed to the end face of the rotor 220 on the side opposite to the stator 210. A hollow portion through which the hollow shaft 202 passes is provided in the disk portion 231.

[0111] The hollow shaft 202 is fixed to the upper surface of the rotor 220. The bearing 240 is a so-called crossed roller bearing. The inner circumferential side of the bearing 240 is fixed to the outer circumference of the hollow shaft 202 by an inner circumferential pressing member 242, and the outer circumferential side of the bearing 240 is fixed to the sub-frame 12S2 by an outer circumferential pressing member 241.

[0112] The detection portion 232 of the encoder 230 is arranged to face the disk portion 231 provided on the end face of the rotor 220. The support portion 233 supports the end face side of the detection portion 232 on the side opposite to the disk portion 231 and is fixed to the sub-frame 12S2. In addition, the support portion 233 may be configured to be fixed to the stator 210 and fixed to the stator 210.

[0113] Next, use Figure 5 to illustrate Figure 3 the assembled Figure 4 second arm 12 in the state of the first motor unit 100 and

[0114] As Figure 5 shown, the hub portion 102b of the hollow shaft 102 of the first motor unit 100 protrudes upward from the upper surface of the second arm 12. The hollow shaft 202 of the second motor unit 200 passes through the hollow shaft 102 of the first motor unit 100 and protrudes upward from the upper surface of the second arm 12.

[0115] The first motor 101 and the second motor 201 are arranged in the order of the stator 210, rotor 220, rotor 120 of the first motor 101, and stator 110 of the first motor 101 along the rotation axis AX3 from the lower surface to the upper surface of the second arm 12.

[0116] The encoder 130 of the first motor unit 100 is arranged at a position facing the lower surface side of the rotor 120 in the first motor unit 100, and the encoder 230 of the second motor unit 200 is arranged at a position facing the upper surface side of the rotor 220 in the second motor unit 200. As Figure 5As shown, the encoder 130 and the encoder 230 are arranged at substantially the same height in the direction along the rotation axis AX3.

[0117] As Figure 5 shown, the first motor 101 and the second motor 201 have a hollow portion 12H that penetrates from the lower surface side to the upper surface side of the second arm 12 along the rotation axis AX3. Cables for the hand 13B connected to the hollow shaft 202 of the second motor unit 200, for example, can be routed through the hollow portion 12H.

[0118] <3. Structure of the Rotor>

[0119] Referring to Figures 6 to 10 , an example of the structure of the rotor 120 of the first motor 101 and the rotor 220 of the second motor 201 will be described. The structures of the rotor 120 and the rotor 220 are the same as each other. Figure 6 is a perspective view showing an example of the overall structure of the rotors 120 and 220, Figure 7 is a plan view showing an example of the overall structure of the rotors 120 and 220, observed from the stator side in the axial direction, Figure 8 is a plan view showing an example of the shape of the magnets included in the rotors 120 and 220, Figure 9 is a plan view showing an example of the manner in which a plurality of magnets included in the rotors 120 and 220 are cut out from a plate-shaped magnet sheet, Figure 10 is a graph showing an example of the relationship between the cogging torque and the coefficient of the magnet offset angle. In addition, in the description of Figures 6 to 10 , the "circumferential direction" is the circumferential direction centered on the rotation axis AX3, and the "radial direction" is the radial direction centered on the rotation axis AX3.

[0120] As Figure 6 and Figure 7As shown, the rotors 120 and 220 have an annular rotor core 300. The rotor core 300 has a cylindrical hollow portion 301 extending along the rotation axis AX3 at the center. The rotor core 300 has a hub portion 302 connected to the shaft portion 102a described above and a back yoke portion 303 (an example of a second back yoke) where magnets are arranged on the surface. The rotor core 300 is made of a magnetic material. On the surface of the back yoke portion 303 on the side facing the stator 110 or the stator 210, a plurality of magnets 305 are arranged along the circumferential direction around the rotation axis AX3. In the present embodiment, the case where the number of magnets 305 is 20 (20 poles) is described as an example, but the number of magnets 305 may also be other than 20. The plurality of magnets 305 include: a plurality of (half the number of magnets 305) first magnets 307, which are arranged at equal angular intervals every other one in the above circumferential direction; and a plurality of (half the number of magnets 305) second magnets 309, which are arranged at equal angular intervals every other one in the above circumferential direction. One second magnet 309 is arranged between each pair of first magnets 307 and is arranged at a position deviated from the central angle (representing the central position between two adjacent first magnets 307 in the circumferential direction as the central angle in the circumferential direction) of two adjacent first magnets 307 in the above circumferential direction by a specified offset angle θ1 (an example of a first angle). The first magnet 307 and the second magnet 309 have the same shape as each other. That is, the plurality of magnets 305 have the same shape respectively. In addition, in the present embodiment, when not distinguishing whether the magnet is the first magnet 307 or the second magnet 309, it is described as the magnet 305.

[0121] In addition, in the present embodiment, when explaining the arrangement of each magnet, the reference position as long as it is a uniquely and uniformly determined reference position such as, for example, the center of gravity position of the magnet, the position of one end or the other end in the circumferential direction, or the position of one end or the other end in the radial direction, etc., can be any position. In the present embodiment, for example, the center of gravity position of the magnet is used as the reference. Specifically, as Figure 7 shown, the center of gravity position PG2 of the second magnet 309 is arranged at a position such that this position is at an angle deviated from the bisector Lb of the angle 2θ0 between the centers of gravity positions PG1 of two adjacent first magnets 307 in the circumferential direction ( Figure 7 the clockwise direction in

[0122] by the offset angle θ1, and the radial distance with respect to the rotation axis AX3 is the same distance as the center of gravity position PG1. Figure 7As shown, a plurality of magnets 305 are arranged at unequal intervals in such a manner that a first interval D1 and a second interval D2 smaller than the first interval D1 are alternately repeated at intervals between two circumferentially adjacent magnets 305. Further, the first interval D1 and the second interval D2 are, for example, intervals when taking the same position in the radial direction centered on the rotation axis AX3, such as the center-of-gravity position of the magnet, or the position of one end or the other end on the radial side.

[0123] In addition, the arrangement of the plurality of magnets 305 can also be described in other words as follows. As Figure 7 shown, a plurality of magnets 305 are arranged at unequal intervals in such a manner that a first angle θA and a second angle θB smaller than the first angle θA are alternately repeated at angles formed by two circumferentially adjacent magnets 305. Further, the position serving as the reference for the angle between the magnets can be any position as long as it is a uniquely and uniformly determined reference position, such as the center-of-gravity position of the magnet, or the position of one end or the other end on the circumferential side. In the present embodiment, as Figure 7 shown, the angles are set with reference to the center-of-gravity positions PG1, PG2 of the magnets.

[0124] As a result of arranging the plurality of magnets 305 as described above, the gap shape between the first magnet 307 and the second magnet 309 becomes alternately different shapes in the circumferential direction. As Figure 7 shown in the partial enlarged view, the circumferentially adjacent gap shapes S1 and S2 are shapes that are not similar to each other and do not coincide even when rotated around the rotation axis AX3. Further, in Figure 7 , the gap shapes S1, S2 are set as the shapes of the space obtained by extending the space between the first magnet 307 and the second magnet 309 to the outer periphery of the back yoke portion 303, but the same applies when setting the shape of only the space between the first magnet 307 and the second magnet 309.

[0125] As Figure 6 and Figure 7 shown, a first recess 311 for accommodating the first magnet 307 and a second recess 313 for accommodating the second magnet 309 are formed on the surface of the back yoke portion 303 on the side where the magnets 305 are arranged. The first recess 311 is formed in a shape corresponding to the first magnet 307, and the first magnet 307 is fixed, for example, by adhesion. As Figure 7 shown, at least one end on the circumferential side and the other circumferential side of the first magnet 307 abuts against at least one step portion 311a on the circumferential side and the other circumferential side of the first recess 311, whereby the circumferential position of the first magnet 307 is positioned. In addition, the radially inner end of the first magnet 307 abuts against the radially inner step portion 311b of the first recess 311, whereby the radial position of the first magnet 307 is positioned.

[0126] The second recess 313 is formed in a shape corresponding to the second magnet 309, and the second magnet 309 is fixed, for example, by adhesion or the like. At least one end of one circumferential side and the other circumferential side of the second magnet 309 abuts against at least one step portion 313a of one circumferential side and the other circumferential side of the second recess 313, whereby the circumferential position of the second magnet 309 is positioned. In addition, the inner end in the radial direction of the second magnet 309 abuts against the step portion 313b on the inner side in the radial direction of the second recess 313, whereby the radial position of the second magnet 309 is positioned.

[0127] Figure 8 An example of the shape of the magnet 305 (the first magnet 307, the second magnet 309) is shown. As Figure 8 shown, the magnet 305 has a so-called skewed shape in which one side 305a and the other side 305b in the circumferential direction are inclined by a prescribed skew angle θ2 (an example of the second angle) in the same direction with respect to the radial direction DR centered on the rotation axis AX3. In addition, the magnet 305 has a shape in which the outer side 305c and the inner side 305d in the radial direction are linear and parallel. That is, the magnet 305 has a trapezoidal shape in which one pair of opposite sides formed by the sides 305c and 305d are parallel, and the other pair of opposite sides formed by the sides 305a and 305b are not parallel.

[0128] Figure 9 An example of a method of cutting out a plurality of magnets 305 from a magnet sheet is shown. As Figure 9 shown, a plurality of (for example, 32) magnets 305 are manufactured from a parallelogram-shaped magnet sheet 315. The parallelogram of the magnet sheet 315 is a shape similar to the parallelogram (the shape of the divided sheet 317) formed by arranging a pair of magnets 305, 305 with the sides 305b facing each other and the sides 305c, 305d staggered. By equally dividing the magnet sheet 315 in the longitudinal and transverse directions into a plurality of parts, a plurality of (for example, 16) parallelogram-shaped divided sheets 317 similar to the parallelogram of the magnet sheet 315 are formed. Further, by bisecting the divided sheet 317 in the longitudinal direction along a cutting line CL inclined with respect to the sides 305a on both sides in the length direction, a pair of magnets 305, 305 are formed. Thereby, it is possible to prevent a remaining portion from being generated in the magnet sheet 315, and the magnets 305 can be cut out from the magnet sheet 315 without waste.

[0129] Figure 10An example of the relationship between the cogging torque generated in the rotors 120 and 220 and the coefficient K of the offset angle θ1 of the second magnet 309 is shown. When the least common multiple of the number of slots of the stators 110 and 210 and the number of poles of the rotors 120 and 220 is set as LCM and the coefficient is set as K, the offset angle θ1 is represented by the following formula (1). The number of slots is the number of teeth in the stator 110 or the stator 210, and the number of poles is the number of magnets 305 in the rotor 120 or the rotor 220. Figure 10 The magnitude of the cogging torque when the coefficient K is changed from 0 to 1.0 is shown.

[0130] θ1 = K × {(360° / LCM) / 2} … Formula (1)

[0131] For example, when the number of slots of the stators 110 and 210 is set as 24 and the number of poles of the rotors 120 and 220 is set as 20, the least common multiple LCM is 120. In addition, the least common multiple LCM is preferably 6 times or more the number of poles of the rotors 120 and 220. That is, if the skewing angle θ2 of the magnet 305 is increased, the effect of reducing the cogging torque is improved, but depending on the slot combination of the motor, it is sometimes difficult to arrange a plurality of magnets 305 at unequal intervals. In this case, the size of the magnet 305 can also be reduced for arrangement, but this will result in a decrease in the output torque of the motor. When the least common multiple LCM is set as 6 times or more the number of poles, the offset angle θ1 can be reduced by the above formula (1). Thereby, it is possible to suppress the size of the magnet 305 from becoming small, and it is possible to apply both a relatively large skewing angle θ2 and the unequal interval arrangement of the magnets 305 at the same time.

[0132] One period of the waveform of the cogging torque generated in the rotors 120 and 220 is represented by (360° / LCM). Therefore, by setting the offset angle θ1 of the second magnet 309 as half of one period of the waveform of the cogging torque, that is, {(360° / LCM) / 2}, namely, when the coefficient K = 1 in the above formula (1), as Figure 10 shown, compared with the case where the offset angle θ1 is set as 0 degrees (the case where K = 0), the cogging torque can be reduced.

[0133] In addition, as Figure 10 shown, when the coefficient K is changed from 0 to 1.0, in other words, when the offset angle θ1 is changed from 0 degrees to half of one period of the waveform of the cogging torque, that is, {(360° / LCM) / 2}, the cogging torque does not gradually decrease but becomes the lowest value when the coefficient K = 1.0, but becomes the lowest value when the coefficient K is less than 1.0. It is considered that this is due to the following reasons.

[0134] Generally, in an axial-gap motor with an open-slot structure, the surface of the magnets of the rotor is not entirely covered by the teeth (the iron core of the stator) of the stator. Therefore, the magnetic conductance of the magnetic circuit passing through the magnets of the rotor and the teeth of the stator varies greatly, which is one of the reasons for the increase in cogging torque. As in this embodiment, by staggering the arrangement position of the second magnet 309 by the offset angle θ1, the cogging torque can be reduced. However, sometimes manufacturing errors occur in the arrangement position of the second magnet 309. Due to this error, there may be a situation where the cogging torque becomes larger due to the imbalance of the forces acting on each magnet caused by the variation in magnetic conductance. Therefore, in this embodiment, as described above, the first magnet 307 and the second magnet 309 are formed into a skewed shape with a skew angle θ2. As a result, the first magnet 307 and the second magnet 309 can be made to straddle adjacent teeth of the opposing stator, so that the forces caused by the variation in magnetic conductance can be suppressed. Thus, a structure that can stagger the arrangement position of the second magnet 309 by the offset angle θ1 can be realized in practice.

[0135] On the other hand, when the first magnet 307 and the second magnet 309 are formed into a skewed shape, the harmonic components (such as the 4th component, 6th component, etc.) of the cogging torque may increase due to the imbalance in the circumferential direction of the magnet shape. As described above, by setting the coefficient K = 1.0, that is, the offset angle θ1 of the second magnet 309 is half of one period of the waveform of the cogging torque, i.e., {(360° / LCM) / 2}, the 1st component of the cogging torque can be reduced. However, by setting the coefficient K less than 1.0, that is, the offset angle θ1 is less than {(360° / LCM) / 2}, in addition to effectively reducing the 1st component of the cogging torque, the harmonic components can also be effectively reduced.

[0136] Based on the above, by setting the coefficient K to 1.0 or less, that is, by setting the offset angle θ1 as in the following formula (2) to a range that not only includes the same range as {(360° / LCM) / 2} but also includes a range less than {(360° / LCM) / 2}, the cogging torque can be effectively reduced corresponding to both the case where the cogging torque mainly includes the 1st component and the case where it includes harmonic components in addition to the 1st component.

[0137] θ1 ≤ (360° / LCM) / 2 ··· Formula (2)

[0138] In addition, by setting the coefficient K less than 1.0, that is, by setting the offset angle θ1 as in the following formula (3) to a range less than {(360° / LCM) / 2}, the cogging torque can be effectively reduced particularly corresponding to the case where the cogging torque includes harmonic components.

[0139] θ1 < (360° / LCM) / 2 ··· Formula (3)

[0140] In addition, asFigure 10 As shown, the value of the cogging torque when the coefficient K = 1.0 is approximately equal to the value of the cogging torque when the coefficient K = 0.75. In the range where the coefficient K is 0.75 or more and 1.0 or less, the value of the cogging torque can be set to be below the value when the coefficient K = 1.0 (the value when the offset angle θ1 is {(360° / LCM) / 2}). Therefore, by setting the coefficient K to 0.75 or more, that is, by setting the offset angle θ1 to be 0.75×{(360° / LCM) / 2} or more as in the following formula (4), the cogging torque can be appropriately reduced.

[0141] θ1≥0.75×{(360° / LCM) / 2}…Formula (4)

[0142] In addition, as Figure 10 shown, when the coefficient K is near 0.875, the value of the cogging torque becomes the minimum value. Therefore, by setting the coefficient K to be near 0.875, that is, by setting the offset angle θ1 to be near 0.875×{(360° / LCM) / 2} as in the following formula (5), both the fundamental component and the harmonic component of the cogging torque can be more effectively reduced.

[0143] θ1≈0.875×{(360° / LCM) / 2}…Formula (5)

[0144] In addition, the above "near" can also have a certain range as long as the value of the coefficient K or the offset angle θ1 is such that the value of the cogging torque is significantly suppressed compared to the value when the coefficient K = 1.

[0145] In addition, the above description has been made for the case where the first magnet 307 and the second magnet 309 have the same shape, that is, where the plurality of magnets 305 have the same shape as each other, but it is not limited to this. The first magnet 307 and the second magnet 309 can also have different shapes, that is, the plurality of magnets 305 can have different shapes from each other. In this case, Figure 10 the graph changes, and when the coefficient K is less than 0.75, the value of the cogging torque may be below the value when the coefficient K = 1.

[0146] <4. Structure of the stator>

[0147] Refer to Figures 11 to 14 to describe an example of the structure of the stator 110 of the first motor 101 and the stator 210 of the second motor 201. The structures of the stator 110 and the stator 210 are the same as each other. Figure 11 is a perspective view observed from the coil side showing an example of the overall structure of the stators 110 and 210, Figure 12 is a perspective view observed from the wiring board side showing an example of the overall structure of the stators 110 and 210, Figure 13 is a cross-sectional view showing an example of the overall structure of the stators 110 and 210,Figure 14 is a perspective view showing an example of the structure of the bobbin included in the stators 110 and 210. In addition, in the Figures 11 to 14 description, the "circumferential direction" is the circumferential direction centered on the rotation axis AX3, and the "radial direction" is the radial direction centered on the rotation axis AX3.

[0148] As Figures 11 to 13 shown, the stators 110 and 210 have an annular stator core 400. The stator core 400 has a cylindrical opening 401 extending along the rotation axis AX3 at the center. The stator core 400 has an annular back yoke portion 403 (an example of the first back yoke portion), a plurality of teeth 407 to which coils 405 are respectively mounted, and an outer peripheral protrusion portion 404 that houses the wiring substrate 413 on the radially inner side. The stator core 400 is made of a magnetic material. A plurality of coils 405 are arranged on the surface of the back yoke portion 403 on the side facing the rotor 120 or the rotor 220. Specifically, as Figure 11 and Figure 13 shown, a plurality of teeth 407 protrude on one side in the direction from the back yoke portion 403 toward the rotation axis AX3 ( Figure 13 the upper side in

[0149] As Figure 12 and Figure 13 shown, on the other side of the back yoke portion 403 in the direction of the rotation axis AX3 ( Figure 13 the lower side in Figure 13 ), a wiring substrate 413 (an example of a wiring portion) that connects a plurality of lead wires 411 led out from the plurality of coils 405 is arranged. The wiring substrate 413 is an annular substrate having a circular opening 413a communicating with the opening 401 of the back yoke portion 403 on the radially inner side. A predetermined wiring pattern for connecting the plurality of lead wires 411 is formed on the surface of the wiring substrate 413. The stator core 400 has an annular recess 415 on the other side in the direction of the rotation axis AX3 (

[0150] The outer peripheral protrusion portion 404 is on the other side in the direction from the outer peripheral portion of the back yoke portion 403 toward the rotation axis AX3 ( Figure 13a substantially C-shaped protrusion protruding from the lower side of the [description in the original text]. By protruding the outer peripheral protrusion 404 from the back yoke portion 403, the stator core 400 (back yoke portion 403) is configured to have a thick wall at the outer peripheral portion where the outer peripheral protrusion 404 is provided and a thin wall at the inner peripheral portion, which is the inner side of the outer peripheral protrusion 404. The recess 415 is located radially inside the outer peripheral protrusion 404 and is an area surrounded by the outer peripheral protrusion 404.

[0151] As Figure 12 shown, the wiring substrate 413 has a terminal portion 413b protruding radially outward in a part of the circumferential direction, and a cable or the like is connected to the terminal portion 413b. The outer peripheral protrusion 404 has a notch portion 417 extending in the radial direction in a part of the circumferential direction, and the terminal portion 413b of the wiring substrate 413 is received in the notch portion 417. By fitting the terminal portion 413b into the notch portion 417, the circumferential orientation (angle) of the wiring substrate 413 is positioned, and the circumferential position deviation of the wiring substrate 413 is prevented.

[0152] As Figure 12 shown, a plurality of (e.g., six) bolt holes 418 for fixing the stator core 400 to the above-mentioned sub-frames 12S1 and 12S2 are formed in the outer peripheral protrusion 404. The plurality of bolt holes 418 are arranged at equal angular intervals along the circumferential direction. As Figure 13 shown, the bolt holes 418 are formed with a depth from the lower end portion of the outer peripheral protrusion 404 to the inside of the back yoke portion 403. By providing the bolt holes 418 in the outer peripheral protrusion 404, the depth of the bolt holes 418 can be ensured, and the bolt holes 418 can be prevented from obstructing the magnetic path in the back yoke portion 403. On the other hand, since the bolt holes 418 are not formed in the inner peripheral side region of the back yoke portion 403, the magnetic path is not obstructed, and a thin wall can be provided. Therefore, by using this portion as the recess 415 to receive the wiring substrate 413, the space on the other side ( Figure 13 the lower side in the [description in the original text]) of the back yoke portion 403 can be effectively utilized.

[0153] As Figure 13 shown, the back yoke portion 403 has the above-mentioned opening portion 401 at a position radially inside the teeth 407. That is, the inner peripheral surface 401a of the opening portion 401 is located radially inside the radially inner end portion 407a of the teeth 407. A plurality of lead wires 411 respectively led out from the above-mentioned plurality of coils 405 are connected to the wiring substrate 413 through the opening portion 401. A protrusion 419 (an example of an insulating portion) provided in the bobbin 409 is disposed between the lead wire 411 and the inner peripheral surface 401a of the opening portion 401, and the lead wire 411 is insulated from the inner peripheral surface 401a of the opening portion 401 by the protrusion 419.

[0154] Figure 14 Shows an example of the structure of the bobbin 409. AsFigure 14 As shown, the coil 405 is wound continuously by regular winding with respect to two adjacent bobbins 409A and 409B (so-called double winding), has a lead wire 411a for the start of winding on one end side, and a lead wire 411b for the end of winding on the other end side. The two bobbins 409A and 409B each have a protrusion 419a and 419b protruding toward the inside of the opening 401. The protrusions 419a and 419b are made of an insulating material and are formed, for example, in a semi-cylindrical shape. A semi-cylindrical groove portion 401b for fitting the protrusions 419a and 419b is formed on the inner peripheral surface 401a of the opening 401 of the back yoke portion 403. By fitting the protrusions 419a and 419b into the groove portion 401b, the protrusions 419a and 419b are positioned and circumferential position deviation is prevented.

[0155] As Figure 14 shown, the lead wire 411a is led out from the coil 405 wound around the bobbin 409A along the protruding direction of the protrusion 419a, and is connected, for example, by solder or the like to a pin 421 (so-called connection pin) provided at the end of the protrusion 419a. The protrusion 419a has an end face 423 at the other end in the direction of the rotation axis AX3 ( Figure 14 the lower side in). The pin 421 is erected on this end face 423. Similarly, the lead wire 411b is led out from the coil 405 wound around the bobbin 409B along the protruding direction of the protrusion 419b, and is connected, for example, by solder or the like to a pin 421 provided at the end of the protrusion 419b. The protrusion 419b has an end face 423 at the other end in the direction of the rotation axis AX3 ( Figure 14 the lower side in). The pin 421 is erected on this end face 423. The plurality of pins 421 are connected, for example, by solder or the like to corresponding terminals 413c of the wiring substrate 413. The terminal 413c is formed as a notch portion that is recessed radially outward in the opening 413a of the wiring substrate 413 and can accommodate the pin 421. As Figure 13 shown, the wiring substrate 413 is arranged such that the surface on one side ( Figure 13 the upper side in) in the direction of the rotation axis AX3 of the wiring substrate 413 abuts against the end face 423 of the protrusion 419.

[0156] In addition, the coil 405 can also be continuously wound around more than three bobbin holders 409, or can be wound around each bobbin holder 409 one by one instead of continuously winding around multiple bobbin holders. Additionally, another insulating member different from the protrusion 419a of the bobbin holder 409 can be provided between the lead wire 411 and the inner peripheral surface 401a of the opening 401. Further, the two bobbin holders 409 can be integrally formed or can be formed separately and connected. Moreover, the bobbin holder 409 and the protrusion 419 can be integrally formed or can be formed separately and connected. Additionally, the wiring substrate 413 can also be arranged such that a gap is provided between the end face 423 of the protrusion 419, and the surface of the wiring substrate 413 faces the end face 423 of the protrusion 419 with a gap therebetween.

[0157] <5. Effects of the Embodiment>

[0158] As described above, in the stator 110 of the first motor 101 and the stator 210 of the second motor 201 in the present embodiment, the plurality of coils 405 are arranged on one side in the direction of the rotation axis AX3 with respect to the back yoke portion 403, and the wiring substrate 413 is arranged on the other side in the direction of the rotation axis AX3 with respect to the back yoke portion 403. Thus, the coil 405, the back yoke portion 403, and the wiring substrate 413 can be arranged in a straight line along the axial direction, and therefore, compared with the case where the wiring substrate 413 is arranged on the radially outer side of the back yoke portion 403, the outer diameter dimensions of the first motor 101 and the second motor 201 can be miniaturized.

[0159] In addition, for example, when the wiring substrate 413 is arranged between the coil 405 and the back yoke portion 403, it is not possible to wind the amount of coil 405 corresponding to the arrangement space of the wiring substrate 413, so the coil density in the slot is reduced. In the present embodiment, the wiring substrate 413 is arranged on the side of the back yoke portion 403 opposite to the side where the coil 405 is mounted, so the coil density can be increased.

[0160] In addition, in the present embodiment, the stator core 400 can also have a recess 415 on the other side in the direction of the rotation axis AX3 of the back yoke portion 403, and the wiring substrate 413 can be housed in the recess 415. In this case, compared with the case where the wiring substrate 413 is arranged at a position on the other side of the stator core 400, the axial dimensions of the first motor 101 and the second motor 201 can be miniaturized. Additionally, by effectively using the space on the other side of the back yoke portion 403, the generation of useless space can be prevented. Moreover, the wiring substrate 413 can be protected.

[0161] In addition, in the present embodiment, the back yoke portion 403 may also have an opening 401 at a position radially inside the teeth 407 with respect to the rotation axis AX3, and the plurality of lead wires 411 may also be connected to the wiring substrate 413 through the opening 401. In this case, the lead wires 411 can be routed through the radially inner side of the back yoke portion 403 instead of being routed on the radially outer side of the back yoke portion 403. Therefore, the outer diameter dimensions of the first motor 101 and the second motor 201 can be reduced.

[0162] In addition, in the present embodiment, the first motor 101 and the second motor 201 may also have an insulating portion (the protruding portion 419 of the bobbin 409 in the embodiment) made of an insulating material and disposed between the lead wire 411 and the inner peripheral surface 401a of the opening 401. In this case, insulation between the lead wire 411 and the back yoke portion 403 can be ensured.

[0163] In addition, in the present embodiment, the first motor 101 and the second motor 201 may also have a bobbin 409 made of an insulating material and wound with a coil 405 on the outer peripheral surface and mounted on the teeth 407, and the insulating portion may be provided as a protruding portion 419 protruding from the bobbin 409 toward the inside of the opening 401. In this case, the coil 405 is mounted on the teeth 407 with the insulating bobbin 409 interposed therebetween, so that it is not necessary to perform an insulation treatment on the surfaces of the back yoke portion 403 and the teeth 407. In addition, by using the bobbin 409, the winding operation of the coil 405 becomes easy.

[0164] In addition, in the present embodiment, the lead wire 411 may also be led out from the coil 405 along the protruding direction of the protruding portion 419. In this case, the operation of leading out the lead wire 411 of the coil 405 becomes easy. In addition, the protruding portion 419 can be used to fix the lead wire 411.

[0165] In addition, in the present embodiment, a groove portion 401b for fitting the protruding portion 419 may also be formed on the inner peripheral surface 401a of the opening 401 of the back yoke portion 403. In this case, by fitting the protruding portion 419 of the bobbin 409 into the groove portion 401b of the back yoke portion 403, the positioning of the bobbin 409 and the protruding portion 419 and the mounting operation on the teeth 407 become easy. In addition, deviation and vibration of the positions of the protruding portion 419 and the lead wire 411 can be suppressed.

[0166] In addition, in the present embodiment, a plurality of lead wires 411 may be connected by the wiring substrate 413. The protruding portion 419 may also have an end face 423 at the other end in the direction of the rotation axis AX3. The wiring substrate 413 may also be configured to contact the end face 423 of the protruding portion 419. In this case, since the wiring portion is configured as the wiring substrate 413, the wiring operation becomes easier compared to the case of wiring manually using leads or the like. In addition, the connection between the lead wire 411 and the wiring substrate 413 becomes easier, and the automation of the wiring operation can be promoted. Further, by bringing the wiring substrate 413 into contact with the end face 423 of the protruding portion 419, the positioning in the direction of the rotation axis AX3 of the wiring substrate 413 becomes easier.

[0167] In addition, in the present embodiment, the first motor 101 and the second motor 201 may be disposed at the joint portion J3 of the transfer robot 10. In this case, since the outer diameter dimensions of the first motor 101 and the second motor 201 can be reduced, the size of the joint portion J3 of the transfer robot 10 can be reduced.

[0168] And, as described above, for the rotor 120 of the first motor 101 and the rotor 220 of the second motor 201 in the present embodiment, the plurality of magnets 305 arranged in the circumferential direction on the back yoke portion 303 are composed of a plurality of first magnets 307 and a plurality of second magnets 309. The plurality of first magnets 307 are arranged at equal angular intervals in the circumferential direction. One second magnet 309 is arranged between each pair of the first magnets 307 and is arranged at a position deviated from the center angle of two adjacent first magnets 307 in the circumferential direction by a predetermined offset angle θ1. Thereby, the plurality of magnets 305 on the back yoke portion 303 can be arranged at unequal intervals in the circumferential direction, and thus the cogging torque can be effectively reduced.

[0169] In addition, in the present embodiment, when the least common multiple of the number of slots of the stators 110 and 210 and the number of poles of the rotors 120 and 220 is set to LCM, the offset angle θ1 may be set to {(360° / LCM) / 2} or less. In this case, by setting the offset angle θ1 to a value that includes not only a value equal to half of one period of the cogging torque waveform, i.e., {(360° / LCM) / 2}, but also a range of values less than half of one period of the cogging torque waveform, i.e., {(360° / LCM) / 2}, the cogging torque can be effectively reduced including the harmonic components when they are present.

[0170] In addition, in the present embodiment, the first magnet 307 and the second magnet 309 may also be formed into shapes such that the side 305a on one side in the circumferential direction and the side 305b on the other side are inclined by a predetermined skew angle θ2 in the same direction with respect to the radial direction DR centered on the rotation axis AX3. In this case, the first magnet 307 and the second magnet 309 can be formed to straddle the adjacent teeth 407 in the stators 110 and 210. Therefore, even when a manufacturing error occurs in the arrangement position of the second magnet 309, the force caused by the magnetic conductance variation can be suppressed. Thus, in practice, a structure in which the arrangement position of the second magnet 309 is shifted by the offset angle θ1 can be realized.

[0171] In addition, in the present embodiment, the offset angle θ1 may also be made smaller than {(360° / LCM) / 2}. In this case, the harmonic components of the cogging torque can be effectively reduced. Therefore, by having both a structure in which the arrangement position of the second magnet 309 is shifted by the offset angle θ1 and a structure in which the first magnet 307 and the second magnet 309 are skewed shapes, both the fundamental component and the harmonic components of the cogging torque can be effectively reduced.

[0172] In addition, in the present embodiment, the offset angle θ1 may also be set to be 0.75×{(360° / LCM) / 2} or more. In this case, the cogging torque can be made to be equal to or less than the value of the cogging torque when the offset angle θ1 is {(360° / LCM) / 2}. Thereby, a certain range can be set for the preferable value of the offset angle θ1. Thus, in practice, a structure in which the arrangement position of the second magnet 309 is shifted by the offset angle θ1 can be realized.

[0173] In addition, in the present embodiment, the offset angle θ1 may also be set to be near 0.875×{(360° / LCM) / 2}. In this case, the offset angle θ1 can be made near the central value of the preferable range {0.75×(360° / LCM) / 2 ≤ θ1 ≤ (360° / LCM) / 2}. Therefore, both the fundamental component and the harmonic components of the cogging torque can be more effectively reduced.

[0174] In addition, in the present embodiment, the plurality of first magnets 307 and the plurality of second magnets 309 may also be formed into the same shape as each other. In this case, as Figure 10As shown, when the coefficient K is changed from 0 to 1.0, that is, when the offset angle θ1 is changed from 0 degrees to half of one cycle of the cogging torque waveform {(360° / LCM) / 2}, the value of the cogging torque can change in such a way that it gradually decreases to a minimum value and then increases again. Thus, a certain range can be set for the value of the preferred offset angle θ1, and therefore, in practice, a structure in which the arrangement position of the second magnet 309 is offset by the offset angle θ1 can be realized. In addition, since it can be made of magnets of the same shape, the manufacturing cost is low.

[0175] In addition, in the present embodiment, the plurality of first magnets 307 and the plurality of second magnets 309 may be formed in a shape in which the outer side edge 305c and the inner side edge 305d in the radial direction are parallel. In this case, the magnet shape can be simplified and the manufacturing becomes easy. In addition, the magnets 305 can be cut out from the magnet sheet 315 without waste, the yield can be increased, and the cost can be reduced.

[0176] In addition, in the present embodiment, the gap shape between the first magnet 307 and the second magnet 309 may also be set to a shape such that the gap shapes S1 and S2 adjacent in the circumferential direction are not similar to each other and do not coincide even when rotated around the rotation axis AX3. In this case, the plurality of magnets 305 on the back yoke portion 303 can be arranged at unequal intervals in the circumferential direction, and thus the cogging torque can be effectively reduced.

[0177] In addition, in the present embodiment, the least common multiple LCM of the number of slots of the stators 110 and 210 and the number of poles of the rotors 120 and 220 may be set to 6 times or more the number of poles. In this case, the offset angle θ1 can be reduced, so that the size reduction of the magnet 305 can be suppressed, and both a large skew angle θ2 and the unequal interval arrangement of the magnets 305 can be applied at the same time.

[0178] In addition, in the present embodiment, the first motor 101 and the second motor 201 may be arranged at the joint portion J3 of the transfer robot 10. In this case, since the cogging torque of the first motor 101 and the second motor 201 can be reduced, the joint portion J3 of the transfer robot 10 can be driven smoothly.

[0179] <6. Modification Example>

[0180] The embodiments of the present disclosure are not limited to the above content, and various modifications can be made without departing from the gist and technical idea thereof.

[0181] In the above embodiment, it has been described as Figure 15The case where the second magnet 309 is arranged at a position deviated from the offset angle θ1 and the first magnet 307 and the second magnet 309 are formed into a skewed shape inclined by the skew angle θ2 with respect to the radial direction DR is shown, but each magnet may not be formed into a skewed shape. For example, as Figure 16 shown, the second magnet 309A is arranged at a position deviated from the offset angle θ1, and both the first magnet 307A and the second magnet 309A are formed into a shape in which one side 305a and the other side 305b in the circumferential direction are along the radial direction DR centered on the rotation axis AX3. In this case, the plurality of magnets 305A on the back yoke portion 303A can also be arranged at unequal intervals in the circumferential direction, so that the cogging torque can be effectively reduced.

[0182] In addition, in the above-described embodiment, the case where both the first magnet 307 and the second magnet 309 are in a shape in which the outer side edge 305c and the inner side edge 305d in the radial direction are straight and parallel is described, but the edges 305c and 305d may not be straight and parallel. For example, as Figure 17 shown, both the first magnet 307B and the second magnet 309B are such that the outer side edge 305c and the inner side edge 305d in the radial direction are formed into arc shapes centered on the rotation axis AX3. In addition, for example, as Figure 18 shown, it can be set to the following shape: the outer side edge 305c and the inner side edge 305d are formed into arc shapes, and the skew angle θ2 is not provided in each magnet. In Figure 17 and Figure 18 In the case of the shown shapes, the outer side edge 305c and the inner side edge 305d become concentric arc shapes. In the above cases, the plurality of magnets 305B and 305C on the back yoke portions 303B and 303C can also be arranged at unequal intervals in the circumferential direction, so that the cogging torque can be effectively reduced.

[0183] In addition, the above has described the case where the structure of the above-described embodiment is applied to both the first motor 101 and the second motor 201 provided in the joint portion J3 of the transfer robot 10, but it can also be applied to any one of the motors. In addition, the structure of the above-described embodiment can also be applied to the motors of the joint portions J1 and J2 other than the joint portion J3 of the transfer robot 10.

[0184] In the above description, when there are descriptions such as "vertical", "parallel", and "plane", these descriptions do not have a strict meaning. These "vertical", "parallel", and "plane" allow tolerances and errors in design and manufacturing, and mean "substantially vertical", "substantially parallel", and "substantially plane".

[0185] In the above description, when there are descriptions such as "identical", "the same", "equal", "different", etc. regarding appearance dimensions, sizes, shapes, positions, etc., these descriptions do not have a strict meaning. These "identical", "the same", "equal", "different" allow for tolerances and errors in design and manufacturing, and refer to "substantially identical", "substantially the same", "substantially equal", "substantially different".

[0186] In addition to the above, the methods of the above-described embodiments and each modification example can also be appropriately combined for use. Furthermore, although not exemplified one by one, the above-described embodiments and each modification example can be implemented with various changes within the scope not departing from their main ideas.

[0187] The problems to be solved and the effects of the above-described embodiments, modification examples, etc. are not limited to the above content. Through the embodiments, modification examples, etc., it is also possible to solve problems not mentioned above, or achieve effects not mentioned above. Sometimes, only a part of the recorded problems is solved, or only a part of the recorded effects is achieved.

Claims

1. An axial gap motor, comprising: a rotor that rotates about a rotation axis; a stator, which is opposite to the rotor in the direction of the rotation axis; a first back yoke provided on either one of the rotor and the stator; a plurality of teeth protruding from one side of the first back yoke in a direction toward the rotation axis; a plurality of coils mounted on the plurality of teeth; and The connecting portion is disposed on the other side of the first back yoke in the direction of the rotation axis and is connected to a plurality of lead wires led out from the plurality of coils.

2. The axial gap motor according to claim 1, wherein: The first back yoke includes a recessed portion on the other side in the direction of the rotation axis. The wiring portion is received in the recess.

3. The axial gap motor according to claim 1 or 2, wherein: The first back yoke includes an opening portion located on the inner side of the teeth in a radial direction centered on the rotation axis. The plurality of lead wires are connected to the connection portion through the opening.

4. The axial gap motor according to claim 3, wherein: The axial gap motor further includes an insulating portion made of an insulating material, and the insulating portion is disposed between the lead wire and an inner peripheral surface of the opening.

5. The axial gap motor according to claim 4, wherein: The axial gap motor further comprises a winding frame made of the insulating material, the winding frame is wound around the coil on the outer circumference and is mounted on the teeth. The insulating portion is a protrusion that protrudes from the bobbin toward the inside of the opening.

6. The axial gap motor according to claim 5, wherein: The lead wire is led out from the coil along a protruding direction of the protrusion.

7. The axial gap motor according to claim 5, wherein: A groove portion into which the protrusion portion fits is formed on the inner peripheral surface of the opening portion.

8. The axial gap motor according to claim 5, wherein: The wiring portion is a wiring substrate formed with a wiring pattern for connecting the plurality of lead wires. The protrusion has an end surface at the other end in the direction of the rotation axis. The wiring substrate is arranged to be in contact with the end surface or to be opposed to the end surface.

9. The axial gap motor according to claim 1, wherein: The axial gap motor also has: a second back yoke provided on the other of the rotor and the stator; and a plurality of magnets arranged on the second back yoke along a circumferential direction around the rotation axis, The plurality of magnets have: a plurality of first magnets arranged at equal angular intervals in the circumferential direction; as well as The plurality of second magnets are disposed one by one between the plurality of first magnets and are disposed at positions offset by a predetermined first angle from a center angle of two of the first magnets adjacent to each other in the circumferential direction.

10. A robot having an axial gap motor disposed at a joint, wherein: The axial gap motor has: a rotor that rotates about a rotation axis; a stator, which is opposite to the rotor in the direction of the rotation axis; a first back yoke provided on either one of the rotor and the stator; a plurality of teeth protruding from one side of the first back yoke in a direction toward the rotation axis; a plurality of coils mounted on the plurality of teeth; and The connecting portion is disposed on the other side of the first back yoke in the direction of the rotation axis and is connected to a plurality of lead wires led out from the plurality of coils.

11. A robot system comprising: The robot according to claim 10; and A control device controls the actions of the robot.

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