CN111492562A - Rotor and motor - Google Patents

Abstract

A rotor of an alternating motor, comprising: a shaft that rotates around a central axis extending in the vertical direction; a rotor core fixed to the shaft; and a plurality of magnets that are enclosed in the rotor core and are provided at intervals in a circumferential direction around the central axis, wherein the rotor core is provided with salient pole portions that protrude outward in a radial direction around the central axis between the magnets adjacent to each other in the circumferential direction, and core portions are provided radially outward of the magnets, and a circumferential width of the core portions is larger than a circumferential width of the salient pole portions.

Description

Rotors and Motors

technical field

The present invention relates to rotors and motors.

Background technique

The rotor of the motor includes a rotor core that rotates with a shaft, and a plurality of magnets provided in the circumferential direction of the rotor core. Among such rotors, a so-called alternating type rotor is known. For example, Patent Document 1 discloses an alternating rotor in which salient poles are provided between magnets adjacent to each other in the circumferential direction. In this rotor, the magnet is used as one magnetic pole, and the salient pole is used as the other magnetic pole.

prior art literature

Patent Literature

Patent Document 1: Japanese Kokai Publication No. 2012-227989

SUMMARY OF THE INVENTION

The problem to be solved by the invention

Among the alternating-type rotors as described above, there is a general rotor in which one magnetic pole and the other magnetic pole are alternated by a plurality of magnets provided in the circumferential direction (hereinafter, such a rotor is referred to as an all-magnet type rotor). Compared with the rotor), there is a problem that vibration and noise are easily increased. In the case of an alternate type rotor, when the circumferential widths of the real pole portion (magnetic pole with magnets) and the virtual pole portion (without magnets but only the magnetic pole of the iron core) in the circumferential direction are the same, from the virtual pole portion to the There is a difference between the magnetic flux density of the magnetic flux that intersects the stator and the magnetic flux density of the magnetic flux that intersects the stator from the real pole portion. As a result, the electromagnetic force in the radial direction between the rotor and the stator deviates between the real pole portion and the imaginary pole portion, and the rotation of the rotor and the generated torque are not constant, which is a factor that increases vibration and noise.

In view of the above-mentioned circumstances, one object of the present invention is to provide a rotor and a motor capable of suppressing vibration and noise during operation.

means of solving problems

One aspect of the rotor of the present invention is a rotor of an alternating motor including a shaft that rotates around a central axis extending in the up-down direction, a rotor core fixed to the shaft, and a plurality of magnets, These are enclosed in the rotor core, and are provided at intervals in the circumferential direction around the central axis. The rotor core is provided with salient pole portions that are adjacent to each other in the circumferential direction of the magnets. They protrude outward in the radial direction with the center axis as the center, and a core portion is provided on the radial outer side of the magnet, and the circumferential width of the iron core portion is wider than that of the salient pole portion. The width of the direction is large.

One aspect of the motor of the present invention includes the rotor and a stator facing the rotor in the radial direction with a gap therebetween.

Invention effect

According to one aspect of the present invention, a rotor and a motor capable of suppressing vibration and noise during operation are provided.

Description of drawings

FIG. 1 is a schematic cross-sectional view of a motor according to one embodiment.

FIG. 2 is a cross-sectional view of a motor according to an embodiment.

3 is a cross-sectional view of a rotor of one embodiment.

4 is a graph showing a change in the magnetic flux density in the circumferential direction of the rotor when the circumferential width of the core portion is made larger than the circumferential width of the salient pole portion in the rotor according to the embodiment .

FIG. 5 shows the change (distribution) of the magnetic flux density in the circumferential direction of the rotor 13 when the circumferential width of the core portion and the circumferential width of the salient pole portion are made equal in the rotor according to the embodiment. ) of the graph.

6 is a cross-sectional view of a rotor according to a modification of the embodiment.

7 shows changes in magnetic flux density in the circumferential direction of the rotor when the circumferential width of the core portion is made larger than the circumferential width of the salient pole portion in the rotor according to the modification of the embodiment curve graph.

Detailed ways

FIG. 1 is a schematic cross-sectional view of a motor 10 according to the present embodiment. As shown in FIG. 1 , a motor (alternate type motor) 10 includes a housing 11 , a stator 12 , a rotor 13 , a bearing holder 14 , and bearings 15 and 16 , wherein the rotor 13 has a center axis extending in the up-down direction. J-configured shaft 20. The shaft 20 is rotatably supported by the bearings 15 and 16 . The shaft 20 has a cylindrical shape extending in the direction along the central axis J.

In the following description, the direction parallel to the central axis J is simply referred to as the "axial direction" or the "up-down direction", the radial direction centered on the central axis J is simply referred to as the "radial direction", and the central axis J is referred to as the center. The circumferential direction of (ie, the direction around the central axis J) is abbreviated as "circumferential direction". In addition, in the following description, "plan view" means the state seen from the axial direction. In the following drawings, in order to facilitate the understanding of each structure, the actual structure may be different from the scale, the number, and the like of each structure.

FIG. 2 is a cross-sectional view of the motor of the present embodiment. As shown in FIG. 2 , the stator 12 faces the rotor 13 radially outside the rotor 13 with a gap therebetween. The stator 12 has a plurality of teeth 17 provided at intervals in the circumferential direction, and a coil 18 wound around each of the teeth 17 . The teeth 17 are radially opposed to the rotor 13 . The coil 18 generates a magnetic field that is applied to the rotor 13 . In this embodiment, for example, twelve teeth 17 and coils 18 are provided. That is, the number of slots in the motor 10 of the present embodiment is twelve.

FIG. 3 is a cross-sectional view of the rotor of the present embodiment. In addition, in FIG. 3, illustration of the shaft 20 is abbreviate|omitted. As shown in FIGS. 2 and 3 , the rotor 13 includes a shaft 20 (see FIG. 2 ), a rotor core 30 , and a plurality of magnets 50 enclosed in the rotor core 30 .

The rotor core 30 has a cylindrical shape extending in the axial direction. Although illustration is omitted, the rotor core 30 is constituted by, for example, stacking a plurality of plate members in the axial direction. As shown in FIG. 3 , the rotor core 30 includes a fixing hole portion 31 , a magnet housing portion 35 , a first protrusion portion (core portion) 37 , and a second protrusion portion (salient pole portion) 38 .

The fixing hole portion 31 penetrates the rotor core 30 in the axial direction. The shape of the fixing hole portion 31 when viewed in the axial direction is a circular shape with the center axis J as the center. The shaft 20 (see FIG. 2 ) passes through the fixing hole portion 31 . The inner peripheral surface of the fixing hole portion 31 is fixed to the outer peripheral surface of the shaft 20 . Thereby, the rotor core 30 is fixed to the shaft 20 .

The magnet accommodating portion 35 accommodates the magnet 50 . A plurality of magnet accommodating portions 35 are provided on the outer peripheral portion of the rotor core 30 at intervals in the circumferential direction. The plurality of magnet housing portions 35 are arranged at equal intervals in the circumferential direction. The plurality of magnet accommodating portions 35 are arranged at positions equidistant from the center axis J in the radial direction, and are arranged in a so-called concentric shape. The number of the magnet accommodating portions 35 provided in the rotor core 30 is, for example, five.

The magnet accommodating portion 35 extends in the axial direction. The magnet housing portion 35 is a through hole penetrating the rotor core 30 in the axial direction, but may be a bottomed hole formed in a part of the rotor core 30 in the axial direction. The magnet housing portion 35 has an inner support surface 35a, an outer support surface 35b, and end portion support surfaces 35c and 35c. The inner support surface 35 a is provided radially inward in the magnet accommodating portion 35 . The inner support surface 35a is a flat surface perpendicular to the radial direction. The outer support surface 35b is spaced apart from the inner support surface 35a in the radial direction, and is provided in parallel with the inner support surface 35a. The outer support surface 35b is a flat surface perpendicular to the radial direction. The end portion support surfaces 35c, 35c extend radially outward from both ends of the inner support surface 35a in the circumferential direction. The end portion support surface 35c is provided only in a part of the inner support surface 35a side in the direction connecting the inner support surface 35a and the outer support surface 35b. Therefore, in the magnet accommodating part 35, the opening part 35d opened in the circumferential direction is provided between the edge part support surface 35c and the outer support surface 35b. The intervals in the circumferential direction of the plurality of magnet housing portions 35 are, for example, the same as each other. The number of the plurality of magnet storage portions 35 is, for example, five.

The first protruding portion 37 and the second protruding portion 38 are provided on the outer peripheral portion of the rotor core 30 . The first protrusions 37 are arranged on the radially outer side of the magnets 50 accommodated in the magnet accommodating portions 35 . The first protrusions 37 are made of the same material as the rotor core 30 . The first protruding portion 37 is provided as an iron core portion located radially outward of the magnet 50 . The first protrusions 37 protrude radially outward. The first protruding portion 37 has extension surfaces 37a, 37a and an outer peripheral surface 37b. The extension surfaces 37 a and 37 a extend radially outward from both ends in the circumferential direction of the outer support surface 35 b of the magnet housing portion 35 . The outer peripheral surface 37b bulges radially outward from the extending surfaces 37a and 37a on both sides in the circumferential direction. When viewed from the axial direction, the outer peripheral surface 37b has a circular arc shape with a curvature radius R1 centered on the central axis J. The first protruding portion 37 extends continuously in the same cross-sectional shape from one end portion in the axial direction of the rotor iron core 30 to the other end portion in the axial direction of the rotor iron core 30 .

The radial dimension T1 between the radially outer side surface 50b of the magnet 50 and the outer peripheral surface of the rotor core 30 (ie, the outer peripheral surface 37b of the first protrusion 37 ) is smaller than the radial thickness T2 of the magnet 50 . That is, the dimension T1 in the radial direction of the first protrusion 37 serving as the core portion is smaller than the thickness T2 in the radial direction of the magnet 50 .

The second protrusions 38 are located between the magnets 50 adjacent to each other in the circumferential direction. The second protrusions 38 protrude radially outward. When viewed from the axial direction, the outer peripheral surface 38a on the radially outer side of the second protrusion 38 has a circular arc shape with a curvature radius R2 centered on a point C, which is set on the radially outer side of the center axis J. s position. When viewed from the axial direction, the point C is arranged on a line L passing from the center axis J of the rotor core 30 through the centers of the magnets 50 adjacent to each other in the circumferential direction in the circumferential direction. The second protruding portion 38 extends continuously with the same cross section from one end portion in the axial direction of the rotor core 30 to the other end portion in the axial direction of the rotor core 30 .

In the present embodiment, the circumferential width W1 of the first protruding portion 37 is larger than the circumferential width W2 of the second protruding portion 38 (W1>W2). The curvature radius R2 of the outer peripheral surface 38a of the second protrusion 38 is smaller than the curvature radius R1 of the outer peripheral surface 37b of the first protrusion 37 (R1>R3). As shown in FIG. 2 , in the radial direction, the size S2 of the gap between the second protrusion 38 and the teeth 17 is the same as the size S1 of the gap between the first protrusion 37 and the teeth 17 ( S1 = S2 ).

The rotor core 30 has a recessed portion 39 . The concave portion 39 is provided in the outer peripheral portion of the rotor core 30 . The recessed portion 39 is provided between the first protruding portion 37 and the second protruding portion 38 in the circumferential direction. That is, the concave portions 39 are provided on both sides in the circumferential direction of the second protruding portion 38 . The concave portion 39 is recessed radially inward than the first protruding portion 37 and the second protruding portion 38 .

The rotor core 30 has a plurality of holes 40 on the radially outer side of the fixing hole portion 31 and the radially inner side of the magnet accommodating portion 35 . The plurality of holes 40 are arranged at equal intervals in the circumferential direction. In the present embodiment, ten holes 40 are provided in the rotor core 30 . Each hole 40 extends in the axial direction and penetrates the rotor core 30 in the axial direction.

The cross section of the magnet 50 is a rectangle whose longitudinal direction is the radial direction, and the magnet 50 is a substantially quadrangular prism extending in the axial direction. The magnet 50 is inserted into the magnet accommodating portion 35 . Thereby, the magnet 50 is enclosed in the outer peripheral portion of the rotor core 30 . Each magnet 50 is arranged between the second protrusions 38 adjacent to each other in the circumferential direction. The plurality of magnets 50 are arranged at equal intervals in the circumferential direction. That is, the plurality of magnets 50 are provided at intervals in the circumferential direction around the central axis J. In the present embodiment, the number of magnets 50 provided in the rotor 13 is five.

The radially inner side surface 50 a of the magnet 50 is in contact with the inner support surface 35 a of the magnet accommodating portion 35 . The radially outer side surface 50b of the magnet 50 is in contact with the outer support surface 35b of the magnet accommodating portion 35 . Parts of the end surfaces 50c on both sides in the circumferential direction of the magnet 50 are in contact with the end support surfaces 35c of the magnet accommodating portion 35 . The magnet 50 is accommodated in the magnet accommodating portion 35 so as to be positioned in the circumferential direction and the radial direction. The end surfaces 50c on both sides in the circumferential direction of the magnet 50 have outer peripheral side end surfaces 50d located radially outward of the end portion support surface 35c. The outer peripheral side end surface 50d is exposed to the recessed portion 39 from the opening portion 35d of the magnet housing portion 35 .

As described above, the rotor 13 of the present embodiment has ten magnetic poles including the magnets 50 and the second protrusions 38 .

4 is a diagram showing the change (distribution) of the magnetic flux density in the circumferential direction of the rotor 13 when the circumferential width W1 of the first protrusion 37 is made larger than the circumferential width W2 of the second protrusion 38 Graph. As shown in FIG. 4 , in the rotor 13 of the present embodiment, the magnetic The flux density is approximately equal.

As a comparison object with the rotor 13 of the present embodiment, FIG. 5 shows the rotor 13 when the circumferential width W1 of the first protruding portion 37 and the circumferential width W2 of the second protruding portion 38 are made equal. A graph of the change (distribution) of the magnetic flux density in the circumferential direction. As shown in FIG. 5 , in the rotor 13 in which the circumferential width W1 of the first protruding portion 37 and the circumferential width W2 of the second protruding portion 38 are equal, the first protruding portion 37 as the real pole portion is provided with the magnet 50 in the rotor 13 . The protruding portion 37 and the second protruding portion 38 serving as a dummy pole portion in which the magnet 50 is not provided have different magnetic flux densities. Specifically, the magnetic flux density in the first protrusions 37 is higher than the magnetic flux density in the second protrusions 38 . This is because the magnetic flux interlinked with the stator 12 from the side of the second protruding portion 38 is larger than the magnetic flux interlinked with the stator 12 from the side of the first protruding portion 37 .

According to the present embodiment, in the rotor 13 of the alternating-type motor 10, the magnet 50 is enclosed in the rotor core 30, and the width W1 in the circumferential direction of the first protrusion 37 provided on the radially outer side of the magnet 50 is larger than that of the second protrusion. The circumferential width W2 of 38 is large. Thereby, the magnetic flux interlinked from the second protruding portion 38 and the stator 12 can be reduced, and the magnetic flux interlinked from the first protruding portion 37 and the second protruding portion 38 and the stator 12 can be made uniform. As a result, it is possible to reduce the variation in the radial force due to the unevenness of the magnetic flux, and it is possible to reduce the vibration and noise of the rotor 13 during operation. Therefore, the rotor 13 and the motor 10 which can suppress vibration and noise during operation are provided.

In the rotor 13 of the present embodiment, the dimension T1 in the radial direction between the radially outer side surface 50b of the magnet 50 and the outer peripheral surface of the rotor core 30 (ie, the outer peripheral surface 37b of the first protrusion 37 ) is smaller than that of the magnet 50 . The radial thickness T2 is small. Thereby, the magnet 50 can be held in the magnet accommodating portion 35 and closer to the stator 12 side. Therefore, leakage of the magnetic flux at positions other than between the magnet 50 and the teeth 17 is suppressed.

According to the present embodiment, the concave portions 39 recessed toward the radially inner side are provided on both sides in the circumferential direction of the second protruding portion 38 . Thereby, the magnetic flux flowing between the stator 12 and the magnet 50 can be prevented from being diffused, and the flow of the magnetic flux can be smoothed.

According to this embodiment, the outer peripheral side end surface 50 d which is at least a part of the magnet 50 is exposed to the recessed portion 39 . Thereby, the magnetic flux directly flows between the magnets 50 and the stator 12 without passing through a part of the rotor core 30 . As a result, the flow of the magnetic flux can be smoothed.

According to the present embodiment, the magnet 50 is accommodated in the magnet accommodating portion 35 . This prevents the magnets 50 from being detached from the rotor core 30 by centrifugal force when the rotor 13 rotates at a high speed.

According to the motor 10 of the present embodiment, the dimension S2 of the gap between the second protruding portion 38 and the tooth 17 and the dimension S1 of the gap between the first protruding portion 37 and the tooth 17 are the same in the radial direction. Thereby, the electromagnetic force (radial force) in the radial direction between the rotor 13 and the stator 12 can be made uniform in the part where the first protrusions 37 are provided and the part where the second protrusions 38 are provided. As a result, vibration and noise generated in the motor 10 can be reduced.

[Variation of Embodiment]

(Modification) FIG. 6 is a cross-sectional view of a rotor according to a modification of the above-described embodiment. 7 is a graph showing changes in magnetic flux density in the circumferential direction of the rotor when the circumferential width of the core portion is made larger than the circumferential width of the salient pole portion in the rotor according to the modification of the above-described embodiment picture. Compared with the rotor 13 described above, the rotor 13B of the present modification is mainly different in the structure of the second protrusion 38B. In addition, the same code|symbol is attached|subjected to the component of the same form as the said embodiment, and the description is abbreviate|omitted. As shown in FIG. 6 , the rotor 13B of the motor 10 is provided with a first protruding portion 37 and a second protruding portion (salient pole portion) 38B on the outer peripheral portion of the rotor core 30B. In the modification of this embodiment, the circumferential width W1 of the first protrusion 37 is larger than the circumferential width W3 of the second protrusion 38B (W1>W3). The curvature radius R1 of the outer peripheral surface 37b of the first protrusion 37 is equal to the curvature radius R3 of the outer peripheral surface 38a of the second protrusion 38B (R1=R3).

As shown in FIG. 7 , in the rotor 13B of the present embodiment, the first protrusions 37 serving as the real poles on which the magnets 50 are provided and the second protrusions 38B serving as the virtual poles without the magnets 50 are provided. The flux density is approximately equal.

In such a configuration, like the rotor 13 and the motor 10 of the above-described embodiment, the magnetic fluxes interlinked from the first protrusions 37 and the second protrusions 38B and the stator 12 can be made uniform. As a result, variation in radial force due to nonuniformity of magnetic flux can be reduced, and the rotor 13B can be reduced in vibration and noise during operation. Therefore, the rotor 13B and the motor 10 that can suppress vibration and noise during operation are provided.

An embodiment of the present invention has been described above, but each configuration and combination thereof in the embodiment are examples, and additions, omissions, substitutions, and other modifications of configurations are possible without departing from the gist of the present invention. The present invention is not limited by the embodiments.

For example, the application of the motor having the rotor of the above-described embodiment and its modifications is not particularly limited. The motor having the rotor of the above-described embodiment and its modifications is mounted on, for example, an electric pump, an electric power steering apparatus, or the like.

Label description

10: Motor (alternate type motor); 12: Stator; 13, 13B: Rotor; 17: Teeth; 20: Shaft; 30, 30B: Rotor iron core; 37b: outer peripheral surface; 38, 38B: second protrusion (salient pole portion); 38a: outer peripheral surface; 39: recessed portion; 50: magnet; J: central axis; R1, R2, R3: radius of curvature; S1 , S2: the size of the gap; W1, W2: the circumferential width; T1: the size; T2: the thickness.

Claims (8)

1. A rotor of an alternating motor, wherein,

the rotor has:

a shaft that rotates around a central axis extending in the vertical direction;

a rotor core fixed to the shaft; and

a plurality of magnets that are enclosed in the rotor core and are arranged at intervals in a circumferential direction around the center axis,

the rotor core is provided with a salient pole portion that protrudes outward in a radial direction around the central axis between the magnets adjacent to each other in the circumferential direction,

a core portion is provided radially outside the magnet,

the width of the core portion in the circumferential direction is larger than the width of the salient pole portion in the circumferential direction.

2. The rotor of claim 1,

the radius of curvature of the outer peripheral surface of the salient pole portion is smaller than the radius of curvature of the outer peripheral surface of the core portion.

3. The rotor of claim 1 or 2,

the radial dimension between the radially outer side surface of the magnet and the outer peripheral surface of the rotor core is smaller than the radial thickness of the magnet.

4. The rotor of any one of claims 1 to 3,

the rotor core is provided with recesses that are located on both circumferential sides of the salient pole portions and that are recessed toward a radially inner side.

5. The rotor of claim 4,

at least a part of the magnet is exposed to the recess.

6. The rotor of any one of claims 1 to 5,

the rotor core has a magnet housing portion extending in an axial direction, and at least a part of the magnet is housed in the magnet housing portion.

7. A motor, comprising:

the rotor of any one of claims 1 to 6; and

and a stator that faces the rotor with a gap in a radial direction.

8. The motor of claim 7,

the stator has teeth opposed to the rotor in the radial direction,

in the radial direction, a size of a gap between the salient pole portion and the tooth is the same as a size of a gap between the core portion and the tooth.

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