Motors for drones

Abstract

The objective is to improve the suppression of magnetic flux leakage between the rotor's magnetic poles. [Solution] The rotor magnet is provided on a first core and consists of a plurality of main magnets arranged in the circumferential direction, and a first auxiliary magnet and a second auxiliary magnet arranged radially inward from each of the plurality of main magnets, wherein the first auxiliary magnet and the second auxiliary magnet have different polarities, and a first set is formed by combining the main magnet, the first auxiliary magnet and the second auxiliary magnet arranged on one side of the first auxiliary magnet in the circumferential direction, and a second set is formed by combining the main magnet, the first auxiliary magnet and the second auxiliary magnet arranged on the other side of the first auxiliary magnet in the circumferential direction adjacent to the first set, wherein the first set and the second set are arranged in the circumferential direction between the second core and the second core adjacent to the second core.

Description

Technical Field

[0001] The present invention relates to a motor for drones. Background Art

[0002] Conventionally, drone motors for rotating propellers of drones are known. As a drone motor, for example, an inner rotor type motor in which a rotor is disposed radially inward of a stator is known.

[0003] Patent Document 1 discloses that in a rotor of an inner rotor type motor, an auxiliary magnet disposed between main magnets suppresses magnetic path formation on the inner circumferential side of the rotor, thereby suppressing generation of leakage magnetic flux that does not contribute to rotational torque. Prior Art Documents Patent Documents

[0004] Patent Document 1 International Publication No. 2023 / 171560 Summary of the Invention Problem to be Solved by the Invention

[0005] However, in the structure disclosed in Patent Document 1, suppression of magnetic flux leakage between magnetic poles of the rotor is insufficient, and there has been a problem that torque decreases.

[0006] The present invention has been made in view of the above points, and an object of the present invention is to improve suppression of magnetic flux leakage between magnetic poles of a rotor. Means for Solving the Problem

[0007] A drone motor according to one aspect of the present invention comprises a stator, a rotor disposed radially inward of the stator with a gap between them, and a shaft fixed to the rotor, wherein the stator comprises a stator core and stator coils wound around the stator core, and the rotor comprises a rotor core and rotor magnets fixed to the rotor core, wherein the rotor core comprises an annular first core whose radially outer end faces the radially inner end of the stator core with a gap between it, a plurality of spoke-shaped second cores extending radially inward from the radially inner end of the first core, and a third core connected to the radially inner end of the second core and to which the shaft is fixed radially inward, and the rotor magnet The stone is provided on the first core and consists of a plurality of main magnets arranged circumferentially, and a first auxiliary magnet and a second auxiliary magnet arranged radially inward from each of the plurality of main magnets, wherein the first auxiliary magnet and the second auxiliary magnet have different polarities, and a combination of the main magnet, the first auxiliary magnet and the second auxiliary magnet arranged on one side of the first auxiliary magnet in the circumferential direction is called a first set, and a combination of the main magnet, the first auxiliary magnet and the second auxiliary magnet arranged adjacent to the first set in the circumferential direction is called a second set, wherein the first core is arranged circumferentially between the second core and the second core adjacent to the second core, and the first set and the second set are arranged.

[0008] Furthermore, a drone motor according to one aspect of the present invention comprises a stator, a rotor disposed radially inward of the stator with a gap between them, and a shaft fixed to the rotor, wherein the stator comprises a stator core and stator coils wound around the stator core, and the rotor comprises a rotor core and rotor magnets fixed to the rotor core, wherein the rotor core comprises an annular first core whose radially outer end faces the radially inner end of the stator core with a gap between them, a plurality of spoke-shaped second cores extending radially inward from the radially inner end of the first core, and a third core connected to the radially inner end of the second core and to which the shaft is fixed radially inward, The rotor magnet is provided on the first core and consists of a plurality of first magnets arranged circumferentially and a plurality of second magnets arranged circumferentially, wherein the first magnets and the second magnets have different polarities, and a first set is made up of a first magnet and a first magnet arranged on one side of the first magnet in the circumferential direction and arranged in a V shape, and a second set is made up of a second magnet and a second magnet arranged on one side of the second magnet in the circumferential direction and arranged in a V shape, wherein the first set is made up of a first magnet and a second magnet adjacent to the second core in the circumferential direction and at least a portion of the first magnets of the first set are exposed radially inward. [Effects of the Invention]

[0009] According to one aspect of the present invention, it is possible to improve the suppression of magnetic flux leakage between the magnetic poles of the rotor. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view of the drone 100 according to Embodiment 1 of the present invention. [Figure 2] This is a perspective view of a motor 110 according to Embodiment 1 of the present invention. [Figure 3] This is a plan cross-sectional view of a motor 110 according to Embodiment 1 of the present invention. [Figure 4]This is a plan view showing an enlarged view of the vicinity of the main magnet 132a, auxiliary magnet 132b, and auxiliary magnet 132c in the rotor 130 according to Embodiment 1 of the present invention. [Figure 5] This figure shows the magnetic flux density distribution near the main magnet 132a, auxiliary magnet 132b, and auxiliary magnet 132c in the rotor 130 according to Embodiment 1 of the present invention. [Figure 6] This is a plan view showing an enlarged view of the vicinity of magnets 132aa and 132ab in the rotor 130 according to Embodiment 2 of the present invention. [Figure 7] This figure shows the magnetic flux density distribution near magnets 132aa and 132ab in the rotor 130 according to Embodiment 2 of the present invention. [Modes for carrying out the invention]

[0011] The following description of a rotating electric machine according to an embodiment of the present invention will be made with reference to the drawings. Note that in the following drawings, the scale and number of components in each structure may differ from the actual structure in order to make the components easier to understand.

[0012] <Embodiment 1> Figure 1 is a perspective view of a drone 100 according to Embodiment 1 of the present invention. The drone 100 is driven by the rotation of a motor 110, which causes a propeller 180 to rotate. Figure 2 is a perspective view of a motor 110 according to Embodiment 1 of the present invention. Figure 2 shows the drone 100 with the propeller 180 removed. Motor 100 is an example of an inner rotor type motor for drones. Motor 110 rotates around a shaft 140 that extends along the central axis J. The center of the propeller 180 is fixed to the shaft 140.

[0013] Furthermore, in the drawings, the XYZ coordinate system is shown as a three-dimensional Cartesian coordinate system where appropriate. In the XYZ coordinate system, the Z-axis direction is parallel to the axis direction of the central axis J shown in Figure 1. The X-axis direction is the radial direction relative to the central axis J as shown in the illustration. The Y-axis direction is perpendicular to both the X-axis and Z-axis directions. In all of the X-axis, Y-axis, and Z-axis directions, the side indicated by the arrow in the figure is the + side, and the opposite side is the - side.

[0014] Furthermore, in the following explanation, the positive side in the Z-axis direction (+Z side) will be referred to as "one side," and the negative side in the Z-axis direction (-Z side) will be referred to as "the other side." Note that "one side" and "the other side" are merely names used for explanatory purposes and do not limit the actual positional relationship or direction. Unless otherwise specified, the direction parallel to the central axis J (Z-axis direction) will be simply referred to as the "axis direction," the radial direction centered on the central axis J will be simply referred to as the "radial direction," and the circumferential direction centered on the central axis J, i.e., around the axis of the central axis J, will be simply referred to as the "circumferential direction." In the radial direction, the side approaching the central axis J will be referred to as the "inside radial direction," and the side moving away from the central axis J will be referred to as the "outside radial direction." In the circumferential direction, the clockwise side when viewed from the +Z side to the -Z side will be referred to as the "one side circumferential," and the counterclockwise side will be referred to as the "other side circumferential."

[0015] In this specification, "extending in the axial direction" includes not only cases where the material extends strictly in the axial direction, but also cases where the material extends in a direction inclined to the axial direction by an angle of less than 45°. Furthermore, in this specification, "extending radially" includes not only cases where the material extends strictly radially, i.e., perpendicular to the axial direction, but also cases where the material extends in a direction inclined to the radial direction by an angle of less than 45°. Furthermore, "parallel" includes not only cases where the material is strictly parallel, but also cases where the angle between the material and the material is inclined to each other by an angle of less than 45°. Furthermore, "spreading in a direction perpendicular to the axial direction" includes not only cases where the material spreads in a direction perpendicular to the axial direction, but also cases where the material spreads in a direction inclined to the direction perpendicular to the axial direction by an angle of less than 45°.

[0016] As shown in Fig. 1, the drone 100 includes a propeller 180 that drives the drone 100 by rotating, and a motor 110 that rotates the propeller 180. The motor 110 includes a stator 120, a rotor 130 (see Fig. 3) disposed radially inward of the stator 120 via a gap, and a shaft 140 fixed to the rotor 130. The motor 110 also includes a first case 150 that houses the stator 120, the rotor 130, and the shaft 140 from one axial side, and a second case 160 that houses the stator 120, the rotor 130, and the shaft 140 from the other axial side. The other axial end of the first case 150 is spaced apart from the one axial end of the second case 160, and the radially outer side of the stator 120 is exposed through the gap.

[0017] Fig. 3 is a plan cross-sectional view of the motor 110 according to Embodiment 1 of the present invention. Fig. 3 shows the motor 110 cut at an axial position between the other axial end of the first case 150 and the one axial end of the second case 160.

[0018] The stator 120 includes a stator core 121 and a stator coil 122 wound around the stator core 121. The rotor 130 includes a rotor core 131 and a rotor magnet 132 fixed to the rotor core 131.

[0019] The rotor core 131 includes an annular first core 131a whose radially outer end faces the radially inner end of the stator core 121 via a gap, a plurality of spoke-shaped second cores 131b extending radially inward from the radially inner end of the first core 131a, and a third core 131c connected to the radially inner end of the second core 131b and having the shaft 140 fixed thereto radially inward thereof. The second core 131b functions as a bridge connecting the first core 131a and the third core 131c. The rotor magnet 132 is fixed to the first core 131a.

[0020] The rotor magnet 132 includes a plurality of main magnets 132a arranged in the circumferential direction, and auxiliary magnets 132b and 132c arranged radially inward with respect to each of the plurality of main magnets 132a. The main magnet 132a is a magnet that contributes to the torque of the motor 110 and has a specific polarity. In the present embodiment, the N poles and S poles of the main magnets 132a are arranged in the circumferential direction, and the main magnets 132a are alternately arranged such that N poles face each other and S poles face each other. The auxiliary magnet 132b and the auxiliary magnet 132c are magnets having different polarities from each other. For the auxiliary magnet 132b and the auxiliary magnet 132c, the N pole and S pole are arranged in the radial direction: the N pole faces outward with respect to the inner space of the rotor core facing the N pole of the main magnet 132a, and the S pole faces outward with respect to the inner space of the rotor core facing the S pole of the main magnet 132a.

[0021] FIG. 4 is an enlarged plan view showing the vicinity of the main magnet 132a, the auxiliary magnet 132b, and the auxiliary magnet 132c in the rotor 130 according to the first embodiment of the present invention. The first core 131a has a through-hole 131d into which the main magnet 132a is inserted and fixed. The through-hole 131d is a hole that penetrates the first core 131a in the axial direction. The first core 131a has a through-hole 131e and a through-hole 131f into which the auxiliary magnet 132b or the auxiliary magnet 132c is inserted and fixed. The through-hole 131e and the through-hole 131f are holes that penetrate the first core 131a in the axial direction. One through-hole 131e and one through-hole 131f are provided for each through-hole 131d, arranged radially inward of the through-hole 131d, and communicate with the through-hole 131d. The through-hole 131e is provided on one circumferential side of the through-hole 131f. The first core 131a has a convex portion 131ea that positions the auxiliary magnet 132b inserted into the through-hole 131e. The first core 131a has a convex portion 131fa that positions the auxiliary magnet 132c inserted into the through-hole 131f.

[0022] If an auxiliary magnet 132b is inserted into a through-hole 131e that communicates with a certain through-hole 131d, then an auxiliary magnet 132c is inserted into a through-hole 131f that communicates with that through-hole 131d. If an auxiliary magnet 132c is inserted into a through-hole 131e that communicates with a certain through-hole 131d, then an auxiliary magnet 132b is inserted into a through-hole 131f that communicates with that through-hole 131d. Furthermore, if an auxiliary magnet 132c is inserted into a through-hole 131e that communicates with a certain through-hole 131d, then an auxiliary magnet 132c is inserted into a through-hole 131f that communicates with that through-hole 131d and an adjacent through-hole 131d.

[0023] The first core 131a has two sets of through-holes 131d, 131e, and 131f between a given second core 131b and an adjacent second core 131b in the circumferential direction. The first core 131a also has a bridge 131g between two of these through-hole 131d, 131e, and 131f sets, specifically between through-hole 131e and through-hole 131f. Auxiliary magnets 132c are positioned on both sides of the bridge 131g in the circumferential direction.

[0024] Figure 5 shows the magnetic flux density distribution near the main magnet 132a, auxiliary magnet 132b, and auxiliary magnet 132c in the rotor 130 according to Embodiment 1 of the present invention. Figure 5 shows the magnetic flux density distribution in the configuration shown in the plan view of Figure 4.

[0025] As shown in Figure 5, according to Embodiment 1, the magnetic flux density is high in the bridge 131g. That is, by arranging auxiliary magnets 132b and 132c on both sides of the bridge 131g, the bridge 131g can be magnetically saturated while reducing the amount of magnets used, and leakage magnetic flux radially inward of the rotor core 131 can be suppressed.

[0026] <Embodiment 2> Next, Embodiment 2 of the present invention will be described. In the description of Embodiment 2, components similar to those in Embodiment 1 will be denoted by the same reference numerals and their descriptions will be omitted, and only the differences from Embodiment 1 will be described.

[0027] Figure 6 is a magnified plan view showing the vicinity of magnets 132aa and 132ab in the rotor 130 according to Embodiment 2 of the present invention. The rotor 130 according to Embodiment 2 has magnets 132aa and 132ab instead of the main magnet 132a, auxiliary magnet 132b, and auxiliary magnet 132c of Embodiment 1.

[0028] The rotor 130 has magnets 132aa and 132ab as rotor magnets. Magnets 132aa and 132ab are magnets that contribute to the torque of the motor 110 and have specific polarities. Magnet 132aa and magnet 132ab, each as a main magnet, are provided divided in a V-shape that opens outward with respect to each magnetic pole, and are arranged so that they are either N poles or S poles with respect to the inside of the V-shaped region.

[0029] The first core 131a has through holes 131da, 131db, 131dc, and 131dd into which magnets 132ab, 132aa, 132aa, 131dc, and 132ab are inserted and fixed. Through holes 131da, 131db, 131dc, and 131dd are holes that penetrate the first core 131a in the axial direction. Multiple combinations of through holes 131da, 131db, 131dc, and 131dd are arranged in the circumferential direction.

[0030] The through hole 131da is adjacent to one side of the through hole 131db in the circumferential direction. The circumferential distance between the through hole 131da and the through hole 131db is narrower on the radially outer side than on the radially inner side. The through hole 131db is adjacent to one side of the through hole 131dc in the circumferential direction. The circumferential distance between the through hole 131db and the through hole 131dc is wider on the radially outer side than on the radially inner side. The through hole 131dc is adjacent to one side of the through hole 131dd in the circumferential direction. The circumferential distance between the through hole 131da and the through hole 131db is narrower on the radially outer side than on the radially inner side. The through hole 131dd is adjacent to one side of the through hole 131da in the circumferential direction. The circumferential distance between the through hole 131dd and the through hole 131da is wider on the radially outer side than on the radially inner side. Therefore, a certain magnet 132aa and an adjacent magnet 132aa are arranged in a V-shape, and a certain magnet 132ab and an adjacent magnet 132ab are arranged in a V-shape.

[0031] The first core 131a has, in the circumferential direction, one combination each of through holes 131da, 131db, 131dc, and 131dd between a certain second core 131b and an adjacent second core 131b. The first core 131a has a gap 131i that exposes at least a portion of the magnet 132aa inserted in the through hole 131db to the radially inward side, and at least a portion of the magnet 132aa inserted in the through hole 131dc to the radially inward side. The first core 131a also has a protrusion 131h that is exposed radially inward and prevents the magnet 132aa inserted in the through hole 131db and the magnet 132aa inserted in the through hole 131dc from falling out from the radially inward side.

[0032] Figure 7 shows the magnetic flux density distribution near magnets 132aa and 132ab in the rotor 130 according to Embodiment 2 of the present invention. Figure 7 shows the magnetic flux density distribution in the configuration shown in the plan view of Figure 6.

[0033] As shown in Figure 7, according to Embodiment 2, by arranging the air gap 131i radially inside the magnet 132aa, which is the south pole magnet, leakage flux between adjacent magnetic poles can be suppressed.

[0034] According to the present invention described above, by using a rotor structure that can prevent leakage magnetic flux, the weight of the motor can be reduced and the power density can be improved. Furthermore, the bridge and magnet retainer (protrusions for positioning the magnet), which were excessive in terms of ensuring strength, can be omitted, thereby achieving weight reduction. For this reason, the present invention is particularly suitable for drone applications where small size and limited power capacity are required.

[0035] The present invention is not limited to the embodiments described above, and various improvements and design modifications may be made without departing from the spirit of the invention. In addition, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the above description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0036] 100... Drones 110...motor 120...Stata 130... Rotor 140... Shaft 150…Case 1 160…Case 2

Claims

1. It comprises a stator, a rotor disposed radially inward of the stator with a gap between them, and a shaft fixed to the rotor. The stator comprises a stator core and stator coils wound around the stator core. The rotor comprises a rotor core and rotor magnets fixed to the rotor core. The rotor core comprises an annular first core whose radially outer end faces the radially inner end of the stator core via a gap, a plurality of spoke-shaped second cores extending radially inward from the radially inner end of the first core, and a third core connected to the radially inner end of the second core, to which the shaft is fixed radially inward. The rotor magnet consists of a plurality of main magnets provided on the first core and arranged circumferentially, and a first auxiliary magnet and a second auxiliary magnet arranged radially inward from each of the plurality of main magnets. The first auxiliary magnet and the second auxiliary magnet have opposite polarities. The combination of the main magnet, the first auxiliary magnet, and the second auxiliary magnet positioned on one side of the first auxiliary magnet in the circumferential direction is defined as the first set. A second set is formed by combining the main magnet, the first auxiliary magnet, and the second auxiliary magnet, which is positioned adjacent to the first set and located on the other side in the circumferential direction of the first auxiliary magnet. The first core is arranged in the circumferential direction between the second core and the second core adjacent to the second core, and the first set and the second set are positioned accordingly. A motor for drones characterized by the following features.

2. It comprises a stator, a rotor disposed radially inward of the stator with a gap between them, and a shaft fixed to the rotor. The stator comprises a stator core and stator coils wound around the stator core. The rotor comprises a rotor core and rotor magnets fixed to the rotor core. The rotor core comprises an annular first core whose radially outer end faces the radially inner end of the stator core via a gap, a plurality of spoke-shaped second cores extending radially inward from the radially inner end of the first core, and a third core connected to the radially inner end of the second core, to which the shaft is fixed radially inward. The rotor magnet consists of a plurality of first magnets arranged circumferentially on the first core, and a plurality of second magnets arranged circumferentially. The first magnet and the second magnet have opposite polarities. The first set consists of the first magnet and the first magnet arranged in a V-shape on one side of the first magnet in the circumferential direction, The second set consists of the second magnet and the second magnet positioned on one side of the second magnet in the circumferential direction, arranged in a V-shape. The first core is positioned in the circumferential direction between the second core and the second core adjacent to the first core, At least a portion of the first magnet of the first set is exposed radially inward, A motor for drones characterized by the following features.

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