Rotor for axial gap motor, and axial gap motor

Abstract

To improve the suppression effect of an eddy current loss of an axial gap motor.SOLUTION: A rotor for an axial gap motor has a rotor frame, and a plurality of magnets arranged at equal intervals in a circumferential direction of the rotor frame. In a surface perpendicular to an axial direction, among corners of a first magnet being one of the plurality of magnets, a corner at a radially inside end and a circumferentially one-side end is defined as a first corner. In a surface perpendicular to the axial direction, among sides of the first magnet, a side at a radially inside end is defined as a first side. In the surface perpendicular to the axial direction, a line that passes through the first corner, and extends in a direction perpendicular to the first side is defined as a first line. The rotor frame between the first magnet and a second magnet adjacent to the circumferentially one side of the first magnet has a recess that recedes toward the circumferentially one side from the first line.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Recently, axial gap motors have become known for use in EVs (electric vehicles), etc. Axial gap motors have a structure in which the surfaces of a disk-shaped rotor and a stator face each other in the axial direction, allowing for a small axial size and high torque.

[0003] In such an axial gap motor, it is desirable to reduce losses due to eddy currents, etc. Patent Document 1 discloses a structure for an axial gap motor in which eddy current losses are suppressed by providing a notch on the outer periphery of a support member that supports a rotor magnet. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6255231 Summary of the Invention [Problem to be solved by the invention]

[0005] However, Patent Document 1 does not consider eddy currents that occur in support members between multiple rotor magnets arranged in the circumferential direction, leaving room for improvement in suppressing eddy current loss.

[0006] An object of the present invention is to improve the suppression of eddy current loss in an axial gap motor. [Means for solving the problem]

[0007] A rotor according to one aspect of the present invention is a rotor for an axial gap motor, comprising a rotor frame and a plurality of magnets arranged at equal intervals around the rotor frame, wherein, in a plane perpendicular to the axial direction, a corner of a first magnet, which is one of the plurality of magnets, at a radially inner end and one circumferential end is defined as a first angle, and in the plane perpendicular to the axial direction, a radially inner end of one of the sides of the first magnet is defined as a first side, and in the plane perpendicular to the axial direction, a line passing through the first corner and extending in a direction perpendicular to the first side is defined as a first line, and the rotor frame between the first magnet and a second magnet adjacent to the first magnet on one circumferential side has a recess recessed toward one circumferential side with respect to the first line. It is characterized by:

[0008] In one aspect of the rotor described above, each of the plurality of magnets is configured by arranging a plurality of magnets in the radial direction, and the magnets arranged radially outward have a larger circumferential width than the magnets arranged radially inward.

[0009] In the rotor according to one aspect of the present invention, the rotor frame has a through hole that penetrates in the axial direction between the first magnet and the second magnet.

[0010] An axial gap motor according to one aspect of the present invention is characterized by having a stator and the rotor according to the above aspect that faces the stator across a gap. [Effects of the Invention]

[0011] According to one aspect of the present invention, it is possible to improve the suppression of eddy current loss in an axial gap motor. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an exploded perspective view of a motor 100 according to a first embodiment of the present invention. [Figure 2] 2 is an enlarged side view of a part of the rotor 110 of FIG. 1. FIG. [Figure 3]2 is a diagram illustrating the suppression of eddy current loss by the rotor 110 of FIG. 1. FIG. [Figure 4] FIG. 10 is an enlarged side view showing a part of a rotor 2110 according to a second embodiment of the present invention. [Figure 5] FIG. 10 is an enlarged side view showing a part of a rotor 3110 according to a third embodiment of the present invention. [Figure 6] FIG. 6 is a further enlarged side view of the rotor 3110 of FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a motor according to an embodiment of the present invention will be described with reference to the drawings. Note that in the drawings, the scale and number of components may differ from the actual structure in order to make each component easier to understand.

[0014] 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 left side of FIG. 1 is referred to as the "one side," and the right side of FIG. 1 is referred to as the "other side." Note that the terms "one side" and "other side" are names used merely for the purpose of explanation and do not limit the actual positional relationship or direction. Furthermore, 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, i.e., around the axis of the central axis J, is simply referred to as the "circumferential direction." In the radial direction, the side closer to the central axis J is referred to as the "radially inner side," and the side away from the central axis J is referred to as the "radially outer side." In the circumferential direction, the clockwise side when viewed from the left side of FIG. 1 is referred to as the "one circumferential side," and the counterclockwise side is referred to as the "other circumferential side."

[0015] In this specification, "extending in the axial direction" includes not only extending strictly in the axial direction but also extending in a direction tilted by less than 45° with respect to the axial direction. Furthermore, in this specification, "extending in the radial direction" includes not only extending strictly in the radial direction, i.e., in a direction perpendicular to the axial direction, but also extending in a direction tilted by less than 45° with respect to the radial direction. Furthermore, "parallel" includes not only being strictly parallel but also being tilted by an angle of less than 45° with respect to the direction perpendicular to the axial direction. Furthermore, "extending in a direction perpendicular to the axial direction" includes not only extending in a direction perpendicular to the axial direction but also extending in a direction tilted by less than 45° with respect to the direction perpendicular to the axial direction.

[0016] 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 has a rotor 110, a shaft 113, a stator 120, and a stator 130. The shaft 113 is the rotation axis of the motor 100, extending axially along a central axis J. The shaft 113 is fixed to the rotor 110. The motor 100 according to this embodiment has the stator 120 and the stator 130 on both axial sides of the rotor 110, but the present invention is not limited to this and can also be applied to a motor having a stator on only one axial side of the rotor.

[0017] The rotor 110, the stator 120, and the stator 130 are each a substantially disk-shaped member. The stator 120 is disposed on one axial side of the rotor 110 with a gap therebetween. The stator 130 is disposed on the other axial side of the rotor 110 with a gap therebetween.

[0018] The stator 120 has a stator core 121 and an armature coil 124. The stator core 121 has a disk-shaped core back 122 and a plurality of teeth 123 arranged in the circumferential direction and extending from a surface on the other axial side of the core back 122 to the other axial side. The armature coil 124 is arranged by being wound around each of the plurality of teeth 123 of the stator core 121. The stator 130 has a stator core 131 and an armature coil 134. The stator core 131 has a disk-shaped core back 132 and a plurality of teeth 133 arranged in the circumferential direction and extending from a surface on one axial side of the core back 132 to one axial side. The armature coil 134 is arranged by being wound around each of the plurality of teeth 133 of the stator core 131.

[0019] The rotor 110 has a rotor frame 111 and magnets 112. The rotor frame 111 is a disc-shaped member made of a conductive material such as stainless steel or carbon steel. The magnets 112 are fitted into through holes 111a (see FIG. 2) that pass through the rotor frame 111 in the axial direction, and are fixed therein by, for example, an adhesive.

[0020] Fig. 2 is an enlarged side view of a portion of rotor 110 in Fig. 1. Fig. 2 is a view of rotor 110 as seen from one axial side, and is an enlarged view of the vicinity of one of the magnets 112 arranged in the circumferential direction.

[0021] The magnet 112 consists of three magnets, 112a, 112b, and 112c. Each of the magnets 112a, 112b, and 112c is a rectangular parallelepiped, and the cross-sectional shape on a plane perpendicular to the axial direction is rectangular. The magnet 112a is arranged radially outward from the magnet 112b. The magnet 112b is arranged radially outward from the magnet 112c. The circumferential width of the magnet 112a is larger than that of the magnet 112b. The circumferential width of the magnet 112b is larger than that of the magnet 112c. In other words, the magnets of this embodiment are configured by arranging multiple magnets in the radial direction, and the magnets arranged radially outward have a larger circumferential width than the magnets arranged radially inward.

[0022] Each of the magnets 112a, 112b, and 112c fits into a through hole 111a. The rotor frame 111 has a plurality of through holes 111a spaced at equal intervals in the circumferential direction. The rotor 110 has a plurality of magnets 112 arranged at equal intervals in the circumferential direction of the rotor frame 111. The cross-sectional shape of the through hole 111a in a plane perpendicular to the axial direction is the same as the cross-sectional shapes of the magnets 112a, 112b, and 112c in a plane perpendicular to the axial direction. The rotor frame 111 has slits 111b that extend radially outward from the through hole 111a and penetrate the rotor frame 111 in the axial direction. The rotor 110 has the effect of suppressing eddy current loss by having the slits 111b.

[0023] Figure 3 is a diagram illustrating the suppression of eddy current loss by rotor 110 of Figure 1. Figure 3(A) is a diagram showing eddy currents in a conventional rotor with a single magnet arranged in the radial direction. Figure 3(B) is a diagram showing eddy currents in rotor 110 according to the first embodiment of the present invention with three magnets arranged in the radial direction.

[0024] As shown in Figure 3(A), conventional rotor 1110 has a structure in which magnets 1112 are fitted into rotor frame 1111. Rotor 1110 has a single magnet 1112 arranged radially and multiple magnets arranged circumferentially. Magnet 1112 has a rectangular cross-sectional shape on a plane perpendicular to the axial direction.

[0025] As shown in FIG. 3(A), in a plane perpendicular to the axial direction, the corner of magnet 1112 that is the radially inner end and the end on one circumferential side is designated as corner 1111e. Furthermore, in a plane perpendicular to the axial direction, the radially inner end of magnet 1112 is designated as side 1111f. Furthermore, in a plane perpendicular to the axial direction, the line that passes through corner 1111e and extends in a direction perpendicular to side 1111f is designated as line 1111g. In the conventional example of FIG. 3(A), the other circumferential end of rotor frame 1111 between magnet 1112 and the magnet 1112 adjacent to that magnet 1112 on one circumferential side coincides with line 1111g in the circumferential direction and is not located on one circumferential side of line 1111g.

[0026] In this case, the area of the rotor frame 1111 between a magnet 1112 and an adjacent magnet 1112 on one circumferential side of the magnet 1112 becomes wider on the radially outer side, causing eddy currents indicated by arrow A to flow in the rotor frame 1111, resulting in eddy current loss.

[0027] On the other hand, as shown in FIG. 3(B), the rotor 110 according to the first embodiment of the present invention has a structure in which the magnets 112, that is, the magnets 112a, 112b, and 112c are fitted into the rotor frame 111.

[0028] As shown in FIG. 3B, in a plane perpendicular to the axial direction, the corner of the magnet 112 at the radially inner end and one circumferential end is designated as corner 111e. Furthermore, in a plane perpendicular to the axial direction, the radially inner end of the magnet 112 is designated as side 111f. Furthermore, in a plane perpendicular to the axial direction, the line passing through corner 111e and extending in a direction perpendicular to side 111f is designated as line 111g. In this embodiment, the rotor frame 111 between the magnet 112 and the adjacent magnet 112 on one circumferential side of the magnet 112 has a recess 111h recessed toward one circumferential side from line 111g. Therefore, the circumferential width of the rotor frame 111 is narrower than when the other circumferential end of the rotor frame 111 coincides with line 111g in the circumferential direction.

[0029] In the first embodiment, the circumferential width of the rotor frame 111 is narrow, and accordingly the region through which eddy currents flow is narrow. Therefore, in the first embodiment, the eddy currents flowing in the rotor frame 111 are the eddy currents indicated by arrow B, the eddy currents indicated by arrow C, and the eddy currents indicated by arrow D, and the paths of the eddy currents flowing in the rotor frame 111 are subdivided, making it possible to reduce eddy current loss compared to the case where the eddy current indicated by arrow A in Fig. 3(A) flows. Note that the paths of the eddy currents indicated by the arrows in the figure are simplified images, not actual paths.

[0030] Second Embodiment Fig. 4 is an enlarged side view of a portion of rotor 2110 according to a second embodiment of the present invention. Rotor 2110 is used in place of rotor 110 in Fig. 1. Fig. 4 is a view of rotor 2110 as seen from one axial side, and is an enlarged view of the vicinity of one of a plurality of magnets 2112 arranged in the circumferential direction.

[0031] The rotor 2110 according to the second embodiment has a structure in which a plurality of single magnets 2112 are arranged in the circumferential direction in the radial direction. The magnets 2112 are rectangular parallelepipeds, and the cross section of the plane perpendicular to the axial direction is rectangular.

[0032] The magnets 2112 fit into through holes 2111a in the rotor frame 2111. The rotor frame 2111 has a plurality of through holes 2111a spaced at equal intervals in the circumferential direction. The rotor 2110 has a plurality of magnets 2112 arranged at equal intervals in the circumferential direction of the rotor frame 2111. The rotor frame 2111 has slits 2111d that extend radially outward from the through holes 2111a and penetrate the rotor frame 2111 in the axial direction. The rotor 2110 has slits 2111db, which have the effect of suppressing eddy current loss.

[0033] The rotor frame 2111 has a through hole 2113 that is connected to the through hole 2111a and passes through in the axial direction on one circumferential side of the through hole 2111a. The through hole 2113 has an R portion 2113a that is curved to alleviate stress concentration caused by the magnet 2112 fitted in the through hole 2111a. The through hole 2113 does not have to be connected to the through hole 2111a. The rotor frame 2111 has a through hole 2114 that is connected to the through hole 2111a and passes through in the axial direction on the other circumferential side of the through hole 2111a. The through hole 2114 has an R portion 2114a that is curved to alleviate stress concentration caused by the magnet 2112 fitted in the through hole 2111a. The through hole 2114 does not have to be connected to the through hole 2111a.

[0034] Rotor frame 2111 has partition portion 2111b between through hole 2111a and through hole 2113. By applying the adhesive used to fix magnet 2112 to through hole 2111a to the surface on the other circumferential side of partition portion 2111b, it is not necessary to fill through hole 2113 with adhesive, and adhesive can be saved. Rotor frame 2111 has partition portion 2111c between through hole 2111a and through hole 2114. By applying the adhesive used to fix magnet 2112 to through hole 2111a to the surface on one circumferential side of partition portion 2111c, it is not necessary to fill through hole 2114 with adhesive, and adhesive can be saved. In order to reduce eddy currents, the circumferential width of the partitions 2111b and 2111c is preferably narrower than the circumferential width of the rotor frame 2111 between the magnet 2112 and the magnet 2112 adjacent to that magnet 2112 on one circumferential side thereof.

[0035] The rotor frame 2111 has, on one circumferential side at the radially inner end of the through hole 2111a, an R portion 2115 which has a curved shape that alleviates stress concentration caused by the magnet 2112 fitted in the through hole 2111a. The rotor frame 2111 has, on the other circumferential side at the radially inner end of the through hole 2111a, an R portion 2116 which has a curved shape that alleviates stress concentration caused by the magnet 2112 fitted in the through hole 2111a.

[0036] 4, among the corners of magnet 2112 on a plane perpendicular to the axial direction, the corner at the radially inner end and one circumferential end is designated as corner 2111e. Furthermore, among the sides of magnet 2112 on a plane perpendicular to the axial direction, the side at the radially inner end is designated as side 2111f. Furthermore, on the plane perpendicular to the axial direction, the line that passes through corner 2111e and extends in a direction perpendicular to side 2111f is designated as line 2111g.

[0037] In this embodiment, the rotor frame 2111 between the magnet 2112 and the magnet 2112 adjacent to that magnet 2112 on one circumferential side has a recess 2111h that is recessed toward one circumferential side from the line 2111g. Therefore, the circumferential width of the rotor frame 2111 is narrower than when the other circumferential end of the rotor frame 2111 coincides with the line 2111g in the circumferential direction.

[0038] In the second embodiment, the region in which eddy currents flow is narrower because the circumferential width of the rotor frame 2111 is narrower. Therefore, in the second embodiment, the eddy currents flowing in the rotor frame 2111 are eddy currents indicated by arrows E, and the paths of the eddy currents flowing in the rotor frame 2111 are subdivided, making it possible to reduce eddy current loss compared to when the eddy currents indicated by arrows A in Fig. 3(A) flow. Note that the paths of the eddy currents indicated by the arrows in the figure are simplified images and not actual paths.

[0039] Third Embodiment Fig. 5 is an enlarged side view of a portion of a rotor 3110 according to a third embodiment of the present invention. The rotor 3110 is used in place of the rotor 110 of Fig. 1. Fig. 5 is a view of the rotor 3110 as seen from one axial side, and is an enlarged view of the vicinity of one of the multiple magnets 3112 arranged in the circumferential direction.

[0040] The third embodiment is a combination of the first and second embodiments. That is, a rotor 3110 according to the third embodiment has a rotor frame 3111 and a magnet 3112. The magnet 3112 fits into a through hole 3111a that passes through the rotor frame 3111 in the axial direction.

[0041] Magnet 3112 consists of two magnets, magnets 3112a and 3112b. Magnets 3112a and 3112b are each a rectangular parallelepiped, with a rectangular cross-sectional shape in a plane perpendicular to the axial direction. Magnet 3112a is arranged radially outward of magnet 3112b. The circumferential width of magnet 3112a is greater than the circumferential width of magnet 3112b. In other words, the magnets of this embodiment are configured by arranging multiple magnets in the radial direction, and the magnets arranged radially outward have a greater circumferential width than the magnets arranged radially inward.

[0042] The rotor frame 3111 has a plurality of through holes 3111a spaced equally apart in the circumferential direction. The rotor 3110 has a plurality of magnets 3112 arranged at equal intervals in the circumferential direction of the rotor frame 3111. The rotor frame 3111 has slits 3111d that extend radially outward from the through holes 3111a and penetrate the rotor frame 3111 in the axial direction. The rotor 3110 has slits 3111d, which have the effect of suppressing eddy current loss.

[0043] The rotor frame 3111 has a through hole 3113 that is connected to the through hole 3111a and passes through in the axial direction on one circumferential side of the through hole 3111a at the radial position of the magnet 3112a. The rotor frame 3111 has a through hole 3114 that is connected to the through hole 3111a and passes through in the axial direction on the other circumferential side of the through hole 3111a at the radial position of the magnet 3112a.

[0044] The rotor frame 3111 has a through hole 3117 that is connected to the through hole 3111a and that passes through in the axial direction on one circumferential side of the through hole 3111a at the radial position of the magnet 3112b. The rotor frame 3111 has a through hole 3118 that is connected to the through hole 3111a and that passes through in the axial direction on the other circumferential side of the through hole 3111a at the radial position of the magnet 3112b.

[0045] Rotor frame 3111 has curved R portion 3115 on one circumferential side at the radially inner end of through hole 3111a, which alleviates stress concentration caused by magnet 3112 fitted in through hole 3111a. Rotor frame 3111 has curved R portion 3116 on the other circumferential side at the radially inner end of through hole 3111a, which alleviates stress concentration caused by magnet 3112 fitted in through hole 3111a.

[0046] Fig. 6 is a further enlarged side view of rotor 3110 of Fig. 5. Fig. 6 is a further enlarged view of the vicinity of through-hole 3117. Through-hole 3117 has curved R-section 3117a radially inward of magnet 3112a, which alleviates stress concentration caused by magnet 3112a fitted in through-hole 3111a. Although not shown, through-hole 3118 also has a similar R-section.

[0047] In the third embodiment, the region in which eddy currents flow is narrower because the circumferential width of the rotor frame 3111 is narrower. Therefore, in the third embodiment, the paths of eddy currents flowing in the rotor frame 3111 are subdivided, and eddy current loss can be reduced.

[0048] The present invention is not limited to the above-described embodiments, and various improvements and design changes may be made without departing from the spirit of the present invention. In addition, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0049] 100...motor, 113...shaft, 110...rotor, 111...rotor frame, 112...magnet, 120, 130...stator

Claims

1. A rotor for an axial gap motor, a rotor frame and a plurality of magnets arranged at equal intervals in the circumferential direction of the rotor frame; In a plane perpendicular to the axial direction, a corner of a first magnet that is one of the plurality of magnets and that is located at a radially inner end and one circumferential end is defined as a first corner, In a plane perpendicular to the axial direction, the radially inner end of the first magnet is defined as a first edge, a first line is a line that passes through the first corner and extends in a direction perpendicular to the first side in a plane perpendicular to the axial direction; the rotor frame between the first magnet and the second magnet adjacent to the first magnet on one circumferential side thereof has a recess recessed toward one circumferential side from the first line; A rotor characterized by:

2. Each of the plurality of magnets is configured by arranging a plurality of magnets in a radial direction, and the magnets arranged on the radially outer side have a larger circumferential width than the magnets arranged on the radially inner side.

2. The rotor according to claim 1.

3. the rotor frame has a through hole extending axially between the first magnet and the second magnet; 2. The rotor according to claim 1.

4. a stator; the rotor according to claim 1 facing the stator across a gap; having An axial gap motor characterized by:

Images