Rotor and motor equipped with the same

Abstract

To provide a rotor capable of reducing the generation of vibration and noise, and a motor equipped with the rotor.SOLUTION: A rotor comprises a shaft and a cylindrical rotor core. The shaft extends along a central axis. The rotor core is disposed radially outward of the shaft and extends in the axial direction. The rotor core has a magnet group and a hole. The magnet group is composed of a first magnet portion and a second magnet portion, and a plurality of magnet groups are disposed in the circumferential direction. When viewed from the axial direction, the first magnet portions form a pair of two magnet portions and are spaced apart from each other in the circumferential direction from the radially inner side to the radially outer side. The second magnet portion is disposed between the pair of first magnet portions. The hole portion is disposed radially outward of the magnet group, and a plurality of hole portions are disposed in the circumferential direction, recessed in the axial direction from one end face in the axial direction.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a rotor and a motor including the rotor. [Background technology]

[0002] A conventional rotor includes a shaft and a cylindrical rotor core. The shaft extends along a central axis. The rotor core is disposed radially outward of the shaft and extends in the axial direction. The rotor core has a magnet group that is composed of first magnet portions and second magnet portions and is disposed in a circumferential direction. When viewed from the axial direction, the first magnet portions form a pair of two, and the surfaces that face the outer circumferential surface of the rotor core move away from each other as they move radially outward. The second magnet portions are disposed between the pair of first magnet portions (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2011 / 002043 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional motors, some of the magnetic flux extending radially outward from the magnet group may be directed toward the circumferentially adjacent magnet group. This may increase the total harmonic distortion (THD) of the induced voltage generated when current is applied to the coil of the stator that faces the rotor in the radial direction. This may increase vibration and noise when the rotor rotates.

[0005] An object of the present invention is to provide a rotor capable of reducing the generation of vibration and noise, and a motor including the rotor. [Means for solving the problem]

[0006] An exemplary rotor of the present invention includes a shaft and a cylindrical rotor core. The shaft extends along a central axis. The rotor core is disposed radially outward of the shaft and extends in the axial direction. The rotor core has a magnet group and a hole. The magnet group is composed of a first magnet portion and a second magnet portion, and a plurality of magnet groups are disposed in the circumferential direction. When viewed from the axial direction, the first magnet portions are paired in pairs, and the faces facing the outer circumferential surface of the rotor core are separated from each other in the circumferential direction from the radially inner side to the radially outer side. The second magnet portion is disposed between the pair of first magnet portions. The hole is disposed radially outward of the magnet group, and a plurality of holes are disposed in the circumferential direction, recessed in the axial direction from one end face in the axial direction. Effect of the Invention

[0007] According to an exemplary embodiment of the present invention, it is possible to provide a rotor capable of reducing the generation of vibration and noise, and a motor including the rotor. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a vertical sectional view showing a schematic diagram of a motor according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing a part of the motor according to the first embodiment of the present invention. [Diagram 3] FIG. 3 is an enlarged cross-sectional view showing a magnet group of the motor according to the first embodiment of the present invention. [Figure 4] FIG. 4 is an enlarged cross-sectional view showing a magnet group of a motor according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. In this specification, the rotation axis of the motor 1 is called the "central axis", and the direction parallel to the central axis C is called the "axial direction". In addition, the direction perpendicular to the central axis C of the motor 1 is called the "radial direction", and the direction along the arc centered on the central axis C of the motor 1 is called the "circumferential direction". In this application, the axial direction is defined as the up-down direction, and the shapes and positional relationships of each part will be described. Note that the up-down direction is a name used simply for explanation and does not limit the actual positional relationships and directions in the motor 1.

[0010] First Embodiment (1. Motor configuration) A motor 1 according to an exemplary embodiment of the present invention will be described. Fig. 1 is a vertical cross-sectional view that shows a schematic diagram of the motor 1 according to the embodiment of the present invention, and Fig. 2 is a horizontal cross-sectional view that shows a part of the motor 1. Note that in Fig. 2, the housing 21, the shaft 100, and the coils 23 are omitted from illustration.

[0011] The motor 1 has a rotor 10 and a stator 20. The stator 20 has a housing 21, a stator core 22, and a coil 23. The housing 21 is formed in a cylindrical shape and accommodates the stator core 22. The housing 21 has a bottom plate portion 21a and a top plate portion 21b. The bottom plate portion 21a is disposed axially below the stator core 22 and holds a lower bearing 23a. The top plate portion 21b is disposed axially above the stator core 22 and holds an upper bearing 23b.

[0012] The lower bearing 23a and the upper bearing 23b support a shaft 100 (described later) rotatably relative to the housing 21.

[0013] The stator core 22 is formed by laminating a plurality of annular electromagnetic steel plates in the axial direction. The stator core 22 has a core back 221 and teeth 222. That is, the stator 20 has the core back 221 and the teeth 222. The core back 221 is annular, and is disposed radially outward of the rotor 10 to surround the central axis C. The teeth 222 are disposed in a circumferential direction, protruding radially inward from the core back 221.

[0014] The teeth 222 are arranged at equal intervals in the circumferential direction around the central axis C. In this embodiment, twelve teeth 222 are arranged.

[0015] The teeth 222 have a base portion 222a and an umbrella portion 222b (see FIG. 2). The base portion 222a extends radially inward from the core back 221. The umbrella portion 222b protrudes from a radially inner end portion of the base portion 222a on both circumferential sides. The circumferential length of the umbrella portion 222b is greater than the circumferential length of the radially inner end portion of the base portion 222a.

[0016] The radially inner surface of the umbrella portion 222b is a curved surface along the circumferential direction. When viewed from the axial direction, the radially inner surface of the umbrella portion 222b is formed in an arc shape centered on the central axis C. The radially inner surface of the umbrella portion 222b faces the outer circumferential surface of the rotor core 110 described later with a gap in the radial direction. The umbrella portions 222b adjacent to each other in the circumferential direction are arranged side by side with slots 223 interposed therebetween.

[0017] The coils 23 are formed by winding a conductive wire around the teeth 222 via an insulator (not shown). This allows the coils 23 to be inserted into each slot 223. In this embodiment, the coils 23 are formed by concentrating the conductive wire around the teeth 222. This allows the stator 20 to be made smaller and the manufacturing costs of the motor 1 to be reduced.

[0018] (2. Rotor Configuration) The rotor 10 has a shaft 100 and a rotor core 110. The shaft 100 is a columnar metal member extending along a central axis C that extends vertically. The rotor core 110 is disposed radially outward of the shaft 100 and extends along the axial direction. The rotor core 110 is formed into a cylindrical shape by laminating annular electromagnetic steel plates in the axial direction.

[0019] The rotor core 110 has magnet groups 120N, 120S, a hole 130, and a shaft hole 140. The magnet groups 120N, 120S are arranged in a plurality of numbers in the circumferential direction. In this embodiment, a total of eight magnet groups 120N, 120S are arranged, and the magnet groups 120N and the magnet groups 120S are arranged alternately in the circumferential direction. The magnet group 120N forms an N pole on the outer peripheral surface of the rotor core 110, and four magnet groups are provided. The magnet group 120S forms an S pole on the outer peripheral surface of the rotor core 110, and four magnet groups are provided.

[0020] Magnet group 120N and magnet group 120S have the same configuration, except for the different magnetic poles and circumferential positions on the outer circumferential surface of rotor core 110. The total number of magnet groups 120N and 120S is not limited to eight, and may be, for example, 2×n (n is an integer).

[0021] Each of the magnet groups 120N, 120S is composed of a pair of first accommodating holes 121, a second accommodating hole 122, gaps 125, 126 (see FIG. 3), a pair of first magnet portions 123, and a second magnet portion 124. The first accommodating hole 121, the second accommodating hole 122, and the gaps 125, 126 penetrate the rotor core 110 in the axial direction. The first magnet portion 123 is accommodated in the first accommodating hole 121, and the second magnet portion 124 is accommodated in the second accommodating hole 122. The first accommodating hole 121, the second accommodating hole 122, and the gaps 125, 126 may be concave and not penetrate in the axial direction.

[0022] Hole 130 is disposed radially outside each of magnet groups 120N, 120S at the radially outer end of rotor core 110. A plurality of hole 130 are disposed in the circumferential direction, axially recessed from one axial end face of rotor core 110. In this embodiment, hole 130 is in the form of a slit extending linearly toward the outer circumferential surface of rotor core 110 when viewed from the axial direction, and penetrates in the axial direction.

[0023] Magnetic flux passes less easily through the voids 125, 126 and the holes 130 than through the rotor core 110 where the voids 125, 126 and the holes 130 are not formed. Therefore, by providing the voids 125, 126 and the holes 130, the flow of magnetic flux can be guided in a predetermined direction. For example, by forming the holes 130 in a slit shape, the flow of magnetic flux can be directed in the direction in which the holes 130 extend. Note that non-magnetic parts such as resin parts may be disposed inside the voids 125, 126 and the holes 130.

[0024] The shaft hole 140 extends in the axial direction, and the shaft 100 is press-fitted into the shaft hole 140. This fixes the shaft 100 to the rotor core 110. The shaft hole 140 and the shaft 100 may be fixed by a spline connection. Also, a resin material or a rubber material may be interposed between the shaft hole 140 and the shaft 100. This improves the insulation and vibration-proofing properties of the rotor 10.

[0025] In the motor 1 configured as described above, when a driving current is supplied to the coil 23, a radial magnetic flux is generated in the stator core 22. A magnetic field generated by the magnetic flux of the stator core 22 and a magnetic field generated by the magnetic flux of the magnet groups 120N, 120S interact with each other, generating a torque in the circumferential direction of the rotor 10. This torque causes the rotor 10 to rotate about the central axis C.

[0026] (3. Detailed configuration of magnet group) Fig. 3 is an enlarged cross-sectional view of the magnet group 120N. The coil 23 is not shown in Fig. 3. In the magnet group 120N, a pair of first accommodating holes 121 are arranged symmetrically about a magnetic pole center line d in the circumferential direction when viewed from the axial direction. The magnetic pole center line d is an imaginary line passing through the circumferential center of the second magnet portion 124 and the central axis C in each of the magnet groups 120N and 120S.

[0027] When viewed from the axial direction, the first accommodating hole 121 and the second accommodating hole 122 are rectangular, and the gaps 125, 126 are triangular. The first accommodating hole 121 has the gap 125 arranged on the circumferential outer side and the gap 126 arranged on the circumferential inner side. The second accommodating hole 122 is arranged adjacent to the first accommodating hole 121 in the circumferential direction via the gap 126. In addition, the first accommodating hole 121 of the magnet group 120N and the first accommodating hole 121 of the magnet group 120S, which are adjacent to each other in the circumferential direction, are arranged with a predetermined interval in the circumferential direction.

[0028] When viewed from the axial direction, the surfaces of the pair of first accommodating holes 121 facing the outer circumferential surface of rotor core 110 are spaced apart from each other in the circumferential direction from the radially inner side to the radially outer side.

[0029] The second accommodating holes 122 are disposed at locations between each pair of first accommodating holes 121. When viewed from the axial direction, the second accommodating holes 122 are perpendicular to the magnetic pole center line d and have a shape that is line-symmetrical with respect to the magnetic pole center line d.

[0030] In this embodiment, the first magnet section 123 and the second magnet section 124 are rectangular parallelepipeds, and the type is not particularly limited. The first magnet section 123 and the second magnet section 124 may be, for example, a neodymium magnet or a ferrite magnet. The first magnet section 123 and the second magnet section 124 may also be configured by combining a plurality of divided magnets. In this case, the divided magnets may be arranged at a predetermined interval when viewed from the axial direction.

[0031] In each of the magnet groups 120N, 120S, the radially outer magnetic pole of the first magnet portion 123 is the same as the radially outer magnetic pole of the second magnet portion 124. Also, the radially inner magnetic pole of the first magnet portion 123 is the same as the radially inner magnetic pole of the second magnet portion 124.

[0032] The first magnet portion 123 is disposed adjacent to the gaps 125 and 126 in the circumferential direction in the first accommodating hole 121. The second magnet portion 124 is disposed adjacent to the gap 126 in the circumferential direction in the second accommodating hole 122. In this embodiment, the first magnet portion 123 and the second magnet portion 124 are not in contact with each other in the circumferential direction. That is, the second magnet portion 124 is adjacent to the first magnet portion 123 through the gaps 126 disposed on both sides in the circumferential direction. This makes it possible to suppress the flow of magnetic flux from one surface of the first magnet portion 123 and the second magnet portion 124 toward the other surface in the radial direction. As a result, it is possible to improve the driving efficiency of the motor 1 while improving the torque of the rotor 10.

[0033] In this embodiment, the first magnet portion 123 and the second magnet portion 124 have the same shape. The first magnet portion 123 and the second magnet portion 124 are rectangular when viewed from the axial direction. The first magnet portions 123 form a pair of two, and the surfaces facing the outer circumferential surface of the rotor core 110 move away from each other in the circumferential direction from the radially inner side to the radially outer side. The second magnet portion 124 is disposed between the pair of first magnet portions 123.

[0034] This makes it possible to suppress the flow of magnetic flux from the first magnet portion 123 toward the circumferentially adjacent magnet groups 120N, 120S, thereby suppressing the total harmonic distortion (THD) of the induced voltage that occurs when a current is applied to the coil 23. As a result, it is possible to reduce the vibration and noise of the rotor 10.

[0035] The pair of first magnet sections 123 are arranged symmetrically with respect to the magnetic pole center line d when viewed from the axial direction. The second magnet section 124 is arranged with its long side perpendicular to the magnetic pole center line d when viewed from the axial direction. This allows the flow of magnetic flux from the second magnet section 124 toward the radially outward direction to be directed parallel to the magnetic pole center line d. This makes it possible to suppress the flow of magnetic flux from the second magnet section 124 toward the magnet groups 120N and 120S adjacent in the circumferential direction. As a result, the total harmonic distortion (THD) of the induced voltage generated when a current is applied to the coil 23 can be suppressed.

[0036] In this embodiment, both radial side surfaces of the first magnet portion 123 are in contact with the inner surface of the first accommodating hole 121 over the entire axial direction. Also, the circumferentially inner side surface of the first magnet portion 123 is exposed to the gap 126. The circumferentially outer side surface of the first magnet portion 123 is exposed to the gap 125.

[0037] Both radial side surfaces of the second magnet portion 124 are in contact with the inner surface of the second accommodating hole 122 over the entire axial direction. In addition, both circumferential side surfaces of the second magnet portion 124 are exposed to the gap 126.

[0038] The holes 130 extend parallel to the magnetic pole center line d when viewed from the axial direction and are arranged at equal intervals in the circumferential direction. In this embodiment, the holes 130 are formed to be longer in the radial direction as they approach the magnetic pole center line d when viewed from the axial direction.

[0039] Providing the holes 130 can further suppress the flow of magnetic flux from the first magnet portion 123 and the second magnet portion 124 toward the circumferentially adjacent magnet groups 120N, 120S. Also, the holes 130 are slit-shaped extending linearly toward the outer circumferential surface of the rotor core 110, and can further suppress the flow of magnetic flux from the first magnet portion 123 and the second magnet portion 124 toward the circumferentially adjacent magnet groups 120N, 120S. This can suppress the total harmonic distortion (THD) of the induced voltage generated when a current is applied to the coil 23.

[0040] Furthermore, by forming the holes 130 parallel to the magnetic pole center line d, the flow of magnetic flux from the first magnet section 123 and the second magnet section 124 toward the radially outward direction can be directed parallel to the magnetic pole center line d. This makes it possible to further suppress the flow of magnetic flux from the first magnet section 123 and the second magnet section 124 toward the circumferentially adjacent magnet groups 120N, 120S. As a result, the total harmonic distortion (THD) of the induced voltage generated when a current is applied to the coil 23 can be suppressed.

[0041] Furthermore, the radius of curvature of the outer shape of rotor core 110 facing each magnet group 120N, 120S is smaller than the distance from the center to the radial outer end of rotor core 110. As a result, the gap W between teeth 222 and rotor core 110 increases with increasing distance from magnetic pole center line d in the circumferential direction. This makes it possible to further suppress the flow of magnetic flux from first magnet portion 123 and second magnet portion 124 toward circumferentially adjacent magnet groups 120N, 120S.

[0042] <Second embodiment> Next, a second embodiment of the present invention will be described. Fig. 4 is an enlarged cross-sectional view of the magnet group 120N. For ease of explanation, the same parts as those in the first embodiment shown in Figs. 1 to 3 above are given the same reference numerals. In the second embodiment, the arrangement of the holes 130 is different from that in the first embodiment. The other parts are the same as those in the first embodiment.

[0043] The circumferential interval of the holes 130 arranged in the region radially facing the first magnet portion 123 is smaller than the circumferential interval of the holes 130 arranged in the region radially facing the second magnet portion 124. In this embodiment, in the region radially facing the second magnet portion 124, no holes 130 are provided on the magnetic pole center line d.

[0044] When the holes 130 are provided in a region radially facing the second magnet portion 124, the flow of magnetic flux from the second magnet portion 124 toward the outside in the radial direction may be distorted near both radial ends of the holes 130. In this embodiment, by reducing the region of the holes 130 in the region radially facing the second magnet portion 124, it is possible to reduce distortion of the flow of magnetic flux from the second magnet portion 124. Therefore, it is possible to reduce inhibition of the flow of magnetic flux from the second magnet portion 124 toward the outside in the radial direction by the holes 130. This makes it possible to suppress total harmonic distortion (THD) of the induced voltage generated when a current is applied to the coil 23.

[0045] The holes 130 may be disposed only in the region of the first magnet portion 123 facing the direction in which the magnetic pole center line d extends, as viewed from the axial direction. This can further reduce the inhibition by the holes 130 of the flow of magnetic flux from the second magnet portion 124 toward the radially outward direction.

[0046] <4.Other> The above describes the embodiments of the present invention. The scope of the present invention is not limited to the above-mentioned embodiments. The present invention can be implemented by making various modifications without departing from the spirit of the invention. The above-mentioned embodiments can be combined as appropriate. In the above-mentioned embodiment, the holes 130 are formed in a slit shape, but they may be formed in a circular shape when viewed from the axial direction. By arranging the circular holes 130 in a predetermined arrangement, the flow of magnetic flux can be guided in a predetermined direction. This makes it possible to suppress the total harmonic distortion (THD) of the induced voltage generated when a current is applied to the coil 23.

[0047] In addition, in the above embodiment, the first accommodating hole 121 and the second accommodating hole 122 are aligned in the circumferential direction with the gap 126 therebetween, but the first accommodating hole 121 and the second accommodating hole 122 may be aligned in the circumferential direction without the gap 126. By filling the gap 126 with the core material of the rotor core 110, the strength of the rotor core 110 is improved.

[0048] <5. Notes> As described above, a rotor (10) according to one embodiment of the present disclosure comprises a shaft (100) extending along a central axis, and a cylindrical rotor core (110) arranged radially outward of the shaft and extending along the axial direction, the rotor core being composed of first magnet portions (123) which, when viewed from the axial direction, form a pair of first magnet portions (123) whose surfaces facing the outer peripheral surface of the rotor core move away from each other circumferentially from the radially inner side to the radially outer side, and a second magnet portion (124) arranged between the pair of first magnet portions, and has a magnet group (120N, 120S) arranged in multiple places in the circumferential direction, and hole portions (130) arranged radially outward of the magnet group, recessed in the axial direction from one axial end face, and arranged in multiple places in the circumferential direction (first configuration).

[0049] In addition, in the above first configuration, the second magnet portion may be configured to be arranged perpendicular to a magnetic pole center line (d) passing through the circumferential center of the second magnet portion and the central axis when viewed from the axial direction (second configuration).

[0050] In the first or second configuration, the hole may be in the form of a slit extending linearly in the radial direction when viewed from the axial direction (third configuration).

[0051] In any one of the first to third configurations, the holes may extend parallel to the magnetic pole center line when viewed from the axial direction and be arranged at equal intervals in the circumferential direction (fourth configuration).

[0052] In addition, in any of the above first to fourth configurations, when viewed from the axial direction, the circumferential spacing of the holes arranged in a region radially facing the first magnet portion may be smaller than the circumferential spacing of the holes arranged in a region radially facing the second magnet portion (fifth configuration).

[0053] In addition, in any of the above first to fifth configurations, the radius of curvature of the outer shape of the rotor core facing each of the magnet groups may be smaller than the distance from the center to the radial outer end of the rotor core (sixth configuration).

[0054] In addition, in any of the above first to sixth configurations, the hole portion may be configured to be arranged only in an area where the first magnet portion faces the direction in which the magnetic pole center line extends, when viewed from the axial direction (seventh configuration).

[0055] In addition, in any of the above first to seventh configurations, the second magnet portion may be configured to be adjacent to the first magnet portion via gaps (126) arranged on both circumferential sides (eighth configuration).

[0056] In addition, the motor (1) may be configured to include a rotor of any one of the first to eighth configurations above, a stator (20) having a ring-shaped core back (221) arranged radially outward of the rotor and surrounding the central axis, a plurality of teeth (222) protruding radially inward from the core back and arranged circumferentially, and a coil (23) formed by concentrating winding a conductor around the teeth (ninth configuration). [Industrial Applicability]

[0057] The present invention can be used in, for example, electric devices equipped with motors, automobiles, ships, aircraft, trains, electrically assisted bicycles, wind power generators, and the like. [Explanation of symbols]

[0058] 1 Motor 10 Rotor 20 Stator 21 Housing 21a Bottom plate part 21b Top plate 22 Stator core 23 Coil 23a Lower bearing 23b Upper bearing 100 Shaft 110 Rotor core 120N, 120S magnet group 121 First storage hole 122 Second Receiving Hole 123 First magnet section 124 Second magnet section 125, 126 void 130 Hole 140 Shaft hole 221 Coreback 222 Teeth 222a base 222b Umbrella Department 223 Slots C center axis W Gap d Magnetic pole center line

Claims

1. A shaft extending along a central axis; a cylindrical rotor core disposed radially outward of the shaft and extending along the axial direction; The rotor core is a magnet group including a pair of first magnet sections, the pair being opposed to the outer peripheral surface of the rotor core, and the faces of the first magnet sections being spaced apart from each other in the circumferential direction from the radially inner side to the radially outer side as viewed from the axial direction, and a second magnet section being disposed between the pair of first magnet sections; and a rotor having a plurality of holes arranged radially outward from the magnet group, the holes being recessed in the axial direction from one axial end face and arranged in the circumferential direction.

2. The rotor according to claim 1 , wherein the second magnet portion is disposed, when viewed in the axial direction, perpendicular to a magnetic pole center line passing through a circumferential center of the second magnet portion and the central axis.

3. The rotor according to claim 1 or 2, wherein the hole is in the form of a slit extending linearly toward the outer circumferential surface of the rotor core when viewed in the axial direction.

4. The rotor according to claim 3 , wherein the hole extends parallel to a center line of the magnetic pole when viewed in the axial direction.

5. 5. The rotor according to claim 4, wherein, when viewed from the axial direction, the circumferential spacing of the holes arranged in a region radially opposed to the first magnet portion is smaller than the circumferential spacing of the holes arranged in a region radially opposed to the second magnet portion.

6. 3. The rotor according to claim 1, wherein a radius of curvature of an outer shape of the rotor core facing each of the magnet groups is smaller than a distance from a center to a radially outer end of the rotor core.

7. The rotor according to claim 4 , wherein the hole is disposed only in an area where the first magnet portion faces a direction in which the magnetic pole center line extends, as viewed from the axial direction.

8. The rotor according to claim 1 or 2, wherein the second magnet portion is adjacent to the first magnet portion via gaps disposed on both circumferential sides.

9. A rotor according to claim 1 or 2; A motor comprising: a stator having: an annular core back arranged radially outside the rotor and surrounding the central axis; a plurality of teeth arranged circumferentially and protruding radially inward from the core back; and a coil formed by winding a conductor around the teeth in a concentrated manner.

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