Rotor for axial gap motor, axial gap motor, and drone

Abstract

To improve the performance of an axial gap motor.SOLUTION: A rotor for an axial gap motor includes a rotor core, magnets arranged in a Halbach array on the rotor core, and an insert member of magnetic material inserted between the rotor core and the magnets, the magnets include a first magnet magnetized vertically and a second magnet magnetized horizontally, and the insert member is positioned so as to form a magnetic path at least between the first magnet and the second magnet.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a rotor for an axial gap motor, an axial gap motor, and a drone.

Background Art

[0002] Conventionally, a flying object having rotary wings generally called a drone has been known. A motor is used to rotate the rotary wings of this drone. The motor is an example of a rotating machine. In such a motor, it is desirable to be small and have low losses.

[0003] Patent Document 1 discloses an invention that suppresses eddy current loss by configuring a portion where magnetic flux changes rapidly with a compacted powder core having excellent high-frequency characteristics in a radial gap motor.

[0004] Further, Patent Document 2 discloses an invention that downsizes a motor by adopting a structure in which a magnet is directly attached to a rotating shaft made of a magnetic material in a radial gap motor.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, when using a compacted powder core as in Patent Document 1, there is a problem that the compacted powder core has a lower saturation magnetic flux density than an electromagnetic steel sheet, and it is difficult to obtain a large torque. In the case of a structure in which a magnet is directly attached to the rotating shaft as in Patent Document 2, eddy current loss occurs due to the magnetic flux leaking from the magnet, and the rotating shaft may generate heat.

[0007] In addition, Patent Document 1 and Patent Document 2 disclose a radial gap motor and do not consider an axial gap motor. Therefore, conventionally, there has been room for improvement in the performance of the axial gap motor.

[0008] An object of the present invention is to improve the performance of an axial gap motor.

Means for Solving the Problems

[0009] A rotor according to an aspect of the present invention is a rotor for an axial gap motor, and includes a rotor core, magnets arranged in a Halbach array on the rotor core, and an insertion member made of a magnetic material inserted between the rotor core and the magnets. The magnets include a first magnet magnetized longitudinally and a second magnet magnetized laterally, and the insertion member is provided at least at a position forming a magnetic path between the first magnet and the second magnet.

[0010] In the rotor of the above aspect, the insertion member is provided between the first magnet and the rotor core.

[0011] In the rotor of the above aspect, the insertion member is an annular member extending in the circumferential direction.

[0012] In the rotor of the above aspect, the insertion member is provided across the first magnet and the second magnet.

[0013] An axial gap motor according to an aspect of the present invention includes a stator and the rotor of the above aspect facing the stator via a gap.

[0014] A drone according to an aspect of the present invention includes the axial gap motor of the above aspect and a rotor blade that rotates by the rotation of the rotor.

Advantages of the Invention

[0015] According to one aspect of the present invention, the performance of an axial gap motor can be improved.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0017] Hereinafter, a motor according to an embodiment of the present invention will be described with reference to the drawings. In the following drawings, in order to make each configuration easier to understand, the actual structure, the scale and the number in each structure may be made different.

[0018] Incidentally, the direction in which the central axis J shown in FIG. 1 extends is referred to as the axial direction. In the axial direction, the upper side of FIG. 1 is referred to as the "one side", and the lower side of FIG. 1 is referred to as the "other side". Note that the one side and the other side are names used merely for explanation and do not limit the actual positional relationship and direction. Also, unless otherwise specified, the radial direction centered on the central axis J is simply referred to as the "radial direction", and the circumferential direction centered on the central axis J, that is, the periphery around the central axis J is simply referred to as the "circumferential direction". The side approaching the central axis J in the radial direction is referred to as the "radial inner side", and the side moving away from the central axis J is referred to as the "radial outer side". In the circumferential direction, the clockwise side when viewed from the upper side of FIG. 1 is referred to as the "circumferential one side", and the counterclockwise side is referred to as the "circumferential other side".

[0019] Incidentally, in this specification, "extending in the axial direction" includes not only the case of strictly extending in the axial direction (Z-axis direction), but also the case of extending in a direction inclined within a range of less than 45° with respect to the axial direction. Also, in this specification, "extending in the radial direction" includes not only the case of strictly extending in the radial direction, that is, in a direction perpendicular to the axial direction, but also the case of extending in a direction inclined within a range of less than 45° with respect to the radial direction. Also, "parallel" includes not only the case of being strictly parallel, but also the case of being inclined at an angle of less than 45° with respect to each other. Also, "extending in a direction perpendicular to the axial direction" includes not only the case of strictly extending in a direction perpendicular to the axial direction, but also the case of extending in a direction inclined within a range of less than 45° with respect to the direction perpendicular to the axial direction.

[0020] <First Embodiment> FIG. 1 is a perspective view of a motor 100 according to a first embodiment of the present invention. The motor 100 is an example of an axial gap motor. The motor 100 includes a rotor 110, a rotor 120, a shaft 105, and a stator 130. The shaft 105 is a rotation axis of the motor 100 that extends in the axial direction along the central axis J. The shaft 105 is fixed to the rotor 110 and the rotor 120. The motor 100 according to the present embodiment has the rotor 110 and the rotor 120 on both axial sides of the stator 130, but the present invention is not limited to this, and it can also be applied to a motor having a rotor only on one axial side of the stator.

[0021] The rotors 110, 120, and the stator 130 are substantially disc-shaped members. The rotor 110 is disposed on one axial side of the stator 130 with a gap therebetween. The rotor 120 is disposed on the other axial side of the stator 130 with a gap therebetween.

[0022] The stator 130 includes a stator core 131 and an armature coil 132. The stator core 131 is a disc-shaped member. The armature coil 132 is disposed along the circumferential direction of the stator core 131.

[0023] The rotor 110 includes a rotor core 111 and a magnet 112. The rotor core 111 is a disc-shaped member. The magnet 112 is fixed, for example, by an adhesive to the surface of the rotor core 111 facing the stator core 131 (the surface facing the other axial side).

[0024] The rotor 120 includes a rotor core 121 and a magnet 122. The rotor core 121 is a disc-shaped member. The magnet 122 is fixed, for example, by an adhesive to the surface of the rotor core 121 facing the stator core 131 (the surface facing one axial side).

[0025] FIG. 2 is a perspective view showing an enlarged part of the motor 100. FIG. 2 shows a part of the circumferential direction in a fan shape cut out for the armature coil 132, the stator core 131 at the location where the armature coil 132 is wound, the rotor core 121, and the magnet 122. The magnet 122 is disposed to face the armature coil 132 on the other axial side of the armature coil 132. Similarly, the magnet 112 is disposed to face the armature coil 132 on one axial side of the armature coil 132.

[0026] FIG. 3 is a schematic view showing the arrangement structure of the magnets according to the first embodiment of the present invention. FIG. 3 is a schematic side view of a part of the circumferential direction of the rotor core 121 and the magnet 122 as viewed from the radially outer side. Since the arrangement structure of the magnet 112 is the same as that of the magnet 122, the description of the arrangement structure of the magnet 112 is omitted.

[0027] The magnet 122 is arranged in a Halbach array on the rotor core 121. The magnet 122 has a magnet 1221 magnetized laterally, a magnet 1222 magnetized longitudinally adjacent to one circumferential side of the magnet 1221, and a magnet 1223 magnetized laterally adjacent to one circumferential side of the magnet 1222. Unless otherwise specified, the axial direction is expressed as vertical and the circumferential direction is expressed as horizontal.

[0028] The magnet 1221 has an S pole 1221a and an N pole 1221b on one circumferential side of the S pole 1221a. The magnet 1222 has an S pole 1222a and an N pole 1222b on one axial side of the S pole 1222a. The magnet 1223 has an N pole 1223b and an S pole 1223a on one circumferential side of the N pole 1223b.

[0029] The rotor 120 has an insertion member 1220 adjacent to the other axial side of the magnet 1222. The insertion member 1220 is a plate-like member. The rotor core 121 is a non-magnetic material, and the insertion member 1220 is a magnetic material. The magnets 1221, 1222, and 1223 and the insertion member 1220 are fixed to adjacent members with an adhesive. Also, the magnets 1221 and 1222 and the insertion member 1220 are fixed to the rotor core 121 with an adhesive.

[0030] On one circumferential side of the magnet 1223, a magnet magnetized longitudinally and having an S pole on one axial side of the N pole is arranged. This longitudinally magnetized magnet is fixed to the rotor core 121 with an adhesive via the insertion member 1220 in the same manner as the magnet 1222. That is, the magnet 122 is configured by repeating the arrangement structure shown in FIG. 3 in the circumferential direction. In the present embodiment, among the magnets 122 arranged in a Halbach array, an insertion member 1220 is provided between the longitudinally magnetized magnet and the rotor core 121.

[0031] In the present embodiment, the thickness of the rotor core 121 is constant. The thickness is the axial length unless otherwise specified. The sum of the axial length of the magnet 1222 and the thickness d1 of the insertion member 1220 is equal to the axial length of the magnet 1221. The sum of the axial length of the magnet 1222 and the thickness d1 of the insertion member 1220 is equal to the axial length of the magnet 1223.

[0032] When the insertion member 1220 is not provided, leakage magnetic flux from the N pole 1221b of the magnet 1221 and the N pole 1223b of the magnet 1223 toward the rotor core 121 occurs, and losses in the rotor core 121 occur. On the other hand, in the present embodiment, an insertion member 1220 is provided between the magnet magnetized longitudinally and the rotor core 121. For this reason, as shown by the arrows in FIG. 3, the magnetic flux from the N pole 1221b of the magnet 1221 and the N pole 1223b of the magnet 1223 heads toward the S pole 1222a of the magnet 1222 through the insertion member 1220. Therefore, according to the present embodiment, it is possible to reduce the leakage magnetic flux from the N pole 1221b and the N pole 1223b toward the rotor core 121, and to reduce the losses (Joule losses) in the rotor core 121.

[0033] FIG. 4 is a diagram showing the characteristics of the motor 100 according to the first embodiment of the present invention. FIG. 4 is a graph showing the results obtained by simulating the characteristics of the motor 100 according to the first embodiment of the present invention. In the graph of FIG. 4, the horizontal axis is the thickness d1 of the insertion member 1220. In the graph of FIG. 4, the vertical axis represents torque on the left scale and is for the line indicated by the solid line in the graph. In the graph of FIG. 4, the vertical axis represents Joule loss on the right scale and is for the line indicated by the broken line in the graph.

[0034] When the insertion member 1220 is provided, the axial length of the magnet 1222 is shortened by the thickness d1 of the insertion member 1220. Therefore, as shown in FIG. 4, the thicker the insertion member 1220, the smaller the torque. However, as shown in FIG. 4, by providing the insertion member 1220 having a predetermined thickness, it is possible to reduce the Joule loss, and as a result, the efficiency of the motor 100 can be improved.

[0035] <Second Embodiment> In the second embodiment of the present invention, the structures of FIGS. 1 and 2 are the same as those of the first embodiment, and thus the description thereof is omitted.

[0036] FIG. 5 is a schematic diagram showing the arrangement structure of magnets according to the second embodiment of the present invention, and corresponds to FIG. 3 of the first embodiment. In the second embodiment, it has a magnet 222 instead of the magnet 122 in the first embodiment, has a magnet 2221 instead of the magnet 1221 in the first embodiment, has a magnet 2222 instead of the magnet 1222, has a magnet 2223 instead of the magnet 1223, has an insertion member 2220 instead of the insertion member 1220, and has a rotor core 221 instead of the rotor core 121.

[0037] The magnet 2221 has an S pole 2221a and an N pole 2221b on one side in the circumferential direction of the S pole 2221a. The magnet 2222 has an S pole 2222a and an N pole 2222b on one side in the axial direction of the S pole 2222a. The magnet 2223 has an N pole 2223b and an S pole 2223a on one side in the circumferential direction of the N pole 2223b.

[0038] The insertion member 2220 in the present embodiment is an annular member extending in the circumferential direction. In the first embodiment, the insertion member 1220 was provided only between the magnet magnetized longitudinally and the rotor core 121, but in the present embodiment, the insertion member 2220 is provided between both the magnet magnetized longitudinally and the magnet magnetized laterally and the rotor core 221. The thickness of the insertion member 2220 is constant. The insertion member 2220 is a magnetic material with a thickness d2. The magnets 2221, 2222, and 2223 and the insertion member 2220 are fixed to adjacent members with an adhesive. Also, the insertion member 2220 is fixed to the rotor core 221 with an adhesive.

[0039] In the present embodiment, the thickness of the rotor core 221 is constant. The axial length of the magnet 2222 is equal to the axial length of the magnet 2221. The axial length of the magnet 2222 is equal to the axial length of the magnet 2223.

[0040] In this embodiment, an insertion member 2220 is provided between the magnet 222 and the rotor core 221. Therefore, as shown by the arrow in FIG. 5, the magnetic flux from the N pole 2221b of the magnet 2221 and the N pole 2223b of the magnet 2223 heads toward the S pole 2222a of the magnet 2222 via the insertion member 2220. Thus, according to this embodiment, the leakage magnetic flux from the N pole 2221b and the N pole 2223b toward the rotor core 221 can be reduced, and the loss (Joule loss) in the rotor core 221 can be reduced.

[0041] FIG. 6 is a diagram showing the characteristics of the motor 100 according to the second embodiment of the present invention. FIG. 6 is a graph showing the result obtained by simulating the characteristics of the motor 100 according to the second embodiment of the present invention. In the graph of FIG. 6, the horizontal axis represents the thickness d2 of the insertion member 2220. In the graph of FIG. 6, the vertical axis represents torque on the left scale, which is for the line indicated by the solid line in the graph. In the graph of FIG. 6, the vertical axis represents Joule loss on the right scale, which is for the line indicated by the broken line in the graph.

[0042] When the insertion member 2220 is provided, as shown in FIG. 6, the torque increases as the thickness d2 of the insertion member 2220 increases, and then the torque decreases. Also, as shown in FIG. 6, by providing the insertion member 1220 with a predetermined thickness, the Joule loss can be reduced, and as a result, the efficiency of the motor 100 can be improved.

[0043] <Third Embodiment> In the third embodiment of the present invention, the structures of FIGS. 1 and 2 are the same as those of the first embodiment, and thus the description thereof is omitted.

[0044] FIG. 7(A) is a schematic diagram showing the arrangement structure of magnets according to the third embodiment of the present invention, and corresponds to FIG. 3 of the first embodiment. In the third embodiment, it has magnet 322 instead of magnet 122 in the first embodiment, magnet 3221 instead of magnet 1221 in the first embodiment, magnet 3222 instead of magnet 1222, magnet 3223 instead of magnet 1223, and has insertion members 3220a and 3220b instead of insertion member 1220, and has rotor core 321 instead of rotor core 121.

[0045] Magnet 3221 has an S pole 3221a and an N pole 3221b on one side in the circumferential direction of the S pole 3221a. Magnet 3222 has an S pole 3222a and an N pole 3222b on one side in the axial direction of the S pole 3222a. Magnet 3223 has an N pole 3223b and an S pole 3223a on one side in the circumferential direction of the N pole 3223b.

[0046] The insertion members 3220a and 3220b in the present embodiment are plate-like members that fit into recesses provided in the rotor core 321. Insertion member 3220a is disposed between magnet 3222 and magnet 3223 and the rotor core 321, and spans between the S pole 3222a of magnet 3222 and the N pole 3223b of magnet 3223. Insertion member 3220b is disposed between magnet 3221 and magnet 3222 and the rotor core 321, and spans between the S pole 3222a of magnet 3222 and the N pole 3221b of magnet 3221. The insertion members 3220a and 3220b of the present embodiment are disposed so as to span between a magnet magnetized longitudinally and a magnet magnetized laterally. The insertion member may be provided at a position that forms at least a magnetic path between a magnet magnetized longitudinally and a magnet magnetized laterally.

[0047] FIG. 7(B) is a schematic view seen from one side in the axial direction with magnet 322 removed from FIG. 7(A). The insertion members 3220a and 3220b have an angle θ1 in the circumferential direction centered on the central axis J and It has a certain size. The thicknesses of the insertion members 3220a and 3220b are thinner than the thickness of the rotor core 321. The magnets 3221, 3222, and 3223 and the insertion members 3220a and 3220b are fixed to adjacent members with an adhesive. Also, the insertion members 3220a and 3220b are fixed to the recesses of the rotor core 321 with an adhesive.

[0048] In this embodiment, the thickness of the portion of the rotor core 321 without recesses is equal to the thickness of the portion where the insertion members 3220a and 3220b are fitted into the recesses of the rotor core 321. The axial length of the magnet 3222 is equal to the axial length of the magnet 3221. The axial length of the magnet 3222 is equal to the axial length of the magnet 3223.

[0049] In this embodiment, it has the insertion members 3220a and 3220b arranged spanning between the vertically magnetized magnets and the horizontally magnetized magnets. For this reason, as shown by the arrow in FIG. 7(A), the magnetic flux from the N pole 3221b of the magnet 3221 heads toward the S pole 3222a of the magnet 3222 via the insertion member 3220b. Also, the magnetic flux from the N pole 3223b of the magnet 3223 heads toward the S pole 3222a of the magnet 3222 via the insertion member 3220a. For this reason, according to this embodiment, the leakage magnetic flux from the N pole 3221b and the N pole 3223b toward the rotor core 321 can be reduced, and the loss (Joule loss) in the rotor core 321 can be reduced.

[0050] FIG. 8 is a diagram showing the characteristics of the motor 100 according to the third embodiment of the present invention. FIG. 8 is a graph showing the result obtained by simulating the characteristics of the motor 100 according to the third embodiment of the present invention. In the graph of FIG. 8, the horizontal axis is the angle θ1 of the insertion members 3220a and 3220b. In the graph of FIG. 8, the vertical axis is torque on the left scale, corresponding to the line shown by the solid line in the graph. In the graph of FIG. 8, the vertical axis is Joule loss on the right scale, corresponding to the line shown by the broken line in the graph.

[0051] When the insertion members 3220a and 3220b are provided, as shown in FIG. 8, the torque and joule loss change according to the angle θ1 of the insertion members 3220a and 3220b. Therefore, the angle θ1 of the insertion members 3220a and 3220b can be determined according to the performance required for the motor 100, and as a result, the efficiency of the motor 100 can be improved.

[0052] Note that the motor 100 described in each of the above embodiments can be applied to, for example, a drive motor of a drone. In this case, the drone has the above-described motor 100 and a rotor blade 151 that rotates by the rotation of the rotors 110 and 120.

[0053] The present invention is not limited to the above embodiments, and various improvements and design changes may be made without departing from the spirit of the present invention. In addition, the embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and scope equivalent to the claims are included.

Description of Reference Numerals

[0054] 100... motor, 105... shaft, 110, 120... rotors, 122... rotor core, 122... magnet, 130... stator, 131... stator core, 132... armature coil, 1220... insertion member

Claims

1. A rotor for an axial-gap motor, comprising: a rotor core; magnets arranged in a Halbach array on the rotor core; an insertion member made of a magnetic material inserted between the rotor core and the magnets; and having: the magnets include a first magnet magnetized longitudinally and a second magnet magnetized transversely; the insertion member is provided at least at a position forming a magnetic path between the first magnet and the second magnet. A rotor characterized by the above.

2. The insertion member is provided between the first magnet and the rotor core. The rotor according to claim 1, characterized by the above.

3. The insertion member is an annular member extending in the circumferential direction. The rotor according to claim 1, characterized by the above.

4. The insertion member is provided across the first magnet and the second magnet. The rotor according to claim 1, characterized by the above.

5. A stator; The rotor according to claim 1 facing the stator with a gap therebetween; and having: An axial-gap motor characterized by the above.

6. The axial-gap motor according to claim 5; and a rotating blade rotated by the rotation of the rotor; and having: A drone characterized by the above.

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