JP2018107899A - Rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor capable of suppressing decrease in demagnetization resistance performance of a permanent magnet when a skew structure is adopted.SOLUTION: A rotor includes: a shaft; a plurality of rotor iron cores; and a plurality of permanent magnets. The shaft rotates about a rotation axis. The plurality of rotor iron cores are fixed onto the shaft and laminated along the rotation axis. The plurality of permanent magnets are embedded for the plurality of respective rotor iron cores. At least two permanent magnets that line in a rotation axis direction among the plurality of permanent magnets are arranged in a peripheral direction while being shifted for a prescribed angle. On opposing end surfaces of the permanent magnet shifted for the prescribed angle, a film is formed that is subjected to high coercive-force processing having higher coercive-force compared with an inside of each permanent magnet.SELECTED DRAWING: Figure 4

Description

  Embodiments described herein relate generally to a rotor.

  Conventionally, a so-called magnet-embedded rotating electrical machine in which a permanent magnet is embedded in a rotor core of a rotor is known. In a rotor of this type of rotating electrical machine, a so-called skew structure in which a plurality of rotor cores are stacked along the rotation axis while being shifted in the circumferential direction in order to reduce torque ripple that causes noise and vibration during driving. May have been adopted. When such a structure is adopted, the magnetic unevenness formed on the surface of the rotor core becomes smooth, so that torque ripple can be reduced.

  Here, by adopting a skew structure, the axial end surface of the permanent magnet comes into contact with the rotor core. In such a part, the magnetic resistance is apparently reduced, and the demagnetizing field due to the electron reaction is more applied to the permanent magnet. In such a case, since the demagnetization resistance is weak, it causes demagnetization of the permanent magnet. As a result, there is a possibility that the demagnetization resistance performance of the permanent magnet when viewed with the entire rotor is lowered.

  In order to compensate for the decrease in the demagnetization resistance of the permanent magnet, a method of improving the coercive force of the permanent magnet by diffusing heavy rare earths on the surface of the permanent magnet is also conceivable. However, for example, when the permanent magnet is divided and used corresponding to the skew structure of the rotor core, the interior of the permanent magnet is exposed on the overlapping surface of the skewed rotor cores. When heavy rare earth is diffused on the surface of the permanent magnet, the coercive force inside the permanent magnet remains at the same level as the base material. For this reason, after all, the demagnetization resistance performance deteriorates at the place where the permanent magnets of the rotor core overlap each other, and there is a possibility that the decrease in the demagnetization resistance performance of the permanent magnet when viewed from the whole rotor cannot be suppressed.

JP 2009-136040 A

  The problem to be solved by the present invention is to provide a rotor that can suppress a decrease in demagnetization resistance of a permanent magnet when a skew structure is employed.

  The rotor of the embodiment has a shaft, a plurality of rotor cores, and a plurality of permanent magnets. The shaft rotates around the rotation axis. The plurality of rotor cores are fixed to the shaft and stacked along the rotation axis. The plurality of permanent magnets are embedded for each of the plurality of rotor cores. Further, among the plurality of permanent magnets, at least two permanent magnets arranged in the rotation axis direction are arranged with a predetermined angle shift in the circumferential direction, and compared with the inside of the permanent magnets on the opposing end surfaces of the permanent magnets shifted by a predetermined angle, respectively. Thus, a film is formed by performing a high coercive force high coercive force treatment.

The perspective view which shows the rotary electric machine of 1st Embodiment. The schematic block diagram when the rotary electric machine of 1st Embodiment is seen in the cross section which follows a center axis direction. Explanatory drawing which shows the overlap condition of the end surfaces of the permanent magnet of 1st Embodiment. The schematic diagram which shows the two permanent magnets on the same axis line of 1st Embodiment. The schematic diagram which shows the two permanent magnets on the same axis line of 2nd Embodiment. Explanatory drawing which shows the manufacturing method of the permanent magnet of 2nd Embodiment. The schematic diagram which shows the two permanent magnets on the same axis line of 3rd Embodiment. The schematic diagram which shows the four permanent magnets on the same axis line of 4th Embodiment.

  Hereinafter, a rotor according to an embodiment will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a perspective view of a rotating electrical machine 1 including a rotor 3 according to the first embodiment.
As shown in FIG. 1, the rotating electrical machine 1 is provided with a substantially cylindrical stator 2 (stator core 4) and a radially inner side of the stator 2, and is rotatably provided with respect to the stator 2. And a rotor 3.
In addition, the stator 2 and the rotor 3 are arrange | positioned in the state in which each center axis line was located on the common axis. Hereinafter, the common axis is referred to as a central axis (rotation axis) O, a direction orthogonal to the central axis O is referred to as a radial direction, and a direction around the central axis O is referred to as a circumferential direction.

  The stator 2 has a substantially cylindrical stator core 4. The stator iron core 4 can be formed by laminating a plurality of electromagnetic steel plates or press-molding soft magnetic powder. A plurality of teeth 5 projecting toward the central axis O and arranged at equal intervals in the circumferential direction are integrally formed on the inner peripheral surface of the stator core 4. The teeth 5 have a substantially rectangular cross section. A slot 6 is formed between adjacent teeth 5. An armature winding 7 is wound around each tooth 5 via these slots 6. By supplying power to the armature winding 7, a predetermined magnetic flux is formed in the stator 2.

The rotor 3 is disposed radially inward of the stator core 4. The rotor 3 includes a shaft 13 that extends along the central axis O, and a substantially cylindrical rotor core 8 that is externally fitted and fixed to the shaft 13.
The rotor iron core 8 can be formed by laminating a plurality of electromagnetic steel plates or press-molding soft magnetic powder. The outer diameter of the rotor core 8 is set such that a predetermined air gap G is formed between each of the teeth 5 facing in the radial direction. In addition, a through hole 9 that penetrates in the direction of the central axis O is formed at the radial center of the rotor core 8. The shaft 13 is press-fitted into the through-hole 9, and the shaft 13 and the rotor core 8 rotate together.

  Further, two permanent magnet housing holes 10 are formed in the rotor core 8 in each of the circumferential angle regions of 1/8 round. The two permanent magnet storage holes 10 are each formed to have a rectangular shape when viewed from the direction of the central axis O. Further, the two permanent magnet housing holes 10 are arranged side by side with a predetermined interval in the circumferential direction so as to be V-shaped with the radially outer side opened as viewed from the central axis O direction.

  The permanent magnets 11 are inserted into the permanent magnet housing holes 10 formed in this way, and are fixed by, for example, an adhesive. The permanent magnet 11 is formed in a rectangular parallelepiped shape so as to correspond to the shape of the permanent magnet storage hole 10 and fills the permanent magnet storage hole 10. Thereby, eight magnetic poles are formed on the outer peripheral surface of the rotor core 8.

  Here, since the two permanent magnets 11 are arranged in a V shape in which the radially outer side is opened as viewed from the central axis O direction in each of the circumferential angle regions of 1/8 circumference, the rotor is caused by each permanent magnet 11. It acts to cancel the magnetic flux generated by the stator 2 that crosses the magnetic flux formed in the iron core 8. And the leakage magnetic field of the edge part of each magnetic pole is suppressed.

That is, the two permanent magnets 11 disposed in each of the circumferential angle regions of 1/8 circumference have the same magnetization direction and the same magnetization direction.
In other words, for example, the two permanent magnets 11 disposed in each of the circumferential angle regions of 1/8 round have their radially outer surfaces magnetized with N poles. In this case, in the two permanent magnets 11 arranged in the circumferential angle region of another 周 circumference adjacent in the circumferential direction, the radially outer surface is magnetized to the S pole. Details of the coercive force of the permanent magnet 11 will be described later.

In addition, flux barriers 12 are formed in the permanent magnet housing holes 10 at both ends in the longitudinal direction as viewed from the central axis O direction.
The flux barrier 12 is for suppressing magnetic flux leakage to the rotor core 8 of the permanent magnet 11 housed in the permanent magnet housing hole 10. In other words, the flux barrier 12 only needs to be configured so that the magnetic flux does not easily pass through. For example, the flux barrier 12 can be configured as a hollow portion or filled with resin in the hollow portion.

FIG. 2 is a schematic configuration diagram when the rotary electric machine 1 is viewed in a cross-section along the central axis O direction.
As shown in the figure, the rotor 3 includes two rotor cores 8, and these two rotor cores 8 are stacked along the direction of the central axis O. Further, the two rotor cores 8 are arranged so as to be shifted from each other by a predetermined angle in the circumferential direction. As a result, the permanent magnets 11 arranged in the direction of the central axis O have a so-called skew structure in which they are displaced from each other by a predetermined angle in the circumferential direction. For this reason, the area where the end surfaces 11a of the permanent magnets 11 facing the overlapping surface 8a of the two rotor cores 8 (the end surfaces 11a of the permanent magnets 11 facing each other in the central axis O direction) are in contact with each other. It becomes smaller than the cross-sectional area along the radial direction of each permanent magnet 11.

This will be described in more detail with reference to FIG.
FIG. 3 is a diagram for explaining the overlapping state of the end faces 11a of the respective permanent magnets 11 embedded in the two rotor cores 8.
When the other rotor core 8 is shifted by a predetermined angle as shown by a two-dot chain line in FIG. 3 with respect to one rotor core 8 as shown by a solid line in FIG. 3, the end surfaces 11a of the permanent magnets 11 come into contact with each other. The area Ar1 is smaller than the cross-sectional area Ar2 along the radial direction of the permanent magnet 11.
As described above, when the area Ar1 where the end faces 11a of the permanent magnets 11 are in contact with each other decreases, the demagnetizing magnetic flux easily passes. As a result, when the entire rotor 3 (two rotor cores 8) is viewed. There was a possibility that the demagnetization resistance of the permanent magnet 11 would be lowered. Therefore, the permanent magnet 11 according to the first embodiment employs the following configuration.

FIG. 4 is a diagram schematically showing two permanent magnets 11 on the same axis line embedded in two rotor cores 8.
As shown in the figure, the permanent magnet 11 of each rotor core 8 is provided with a high coercive force processing portion 14 (see hatched portions, the same applies to the following embodiments) on the entire outer peripheral surface.

  For example, the high coercive force processing unit 14 first applies or deposits a heavy rare earth such as dysprosium (Dy) or terbium (Tb) on the entire outer surface of the permanent magnet 11 to form a heavy rare earth film. Then, by diffusing this heavy rare earth film, a high coercive force processing portion 14 thicker than the heavy rare earth film is formed on the surface of the base material of the permanent magnet 11. That is, the high coercive force processing portion 14 can be said to be a heavy rare earth film formed on the surface of the base material of the permanent magnet 11.

  In addition, the thickness of the high coercive force processing unit 14 is, for example, about 1.5 mm to 2.0 mm. Moreover, as a coating method, for example, a so-called dipping method in which the permanent magnet 11 is immersed in a processing solution can be used. Furthermore, as a base material of the permanent magnet 11, for example, a Nd—Fe—B sintered magnet is used. This Nd—Fe—B sintered magnet is an alloy mainly composed of neodymium, iron, and boron.

  By applying the high coercive force processing unit 14 to the entire outer peripheral surface of the permanent magnet 11, the coercive force of the end surface 11a of the permanent magnet 11 facing the overlapping surface 8a of the rotor cores 8 can be increased. More specifically, the improvement in coercive force from the base material at the corners of the permanent magnet 11 is about 400 kA / m to 500 kA / m. For this reason, even if a demagnetizing field acts on the end surface of the end surface 11a of the permanent magnet 11, demagnetization of the permanent magnet 11 can be suppressed.

  Therefore, according to the first embodiment described above, demagnetization of the permanent magnet 11 can be suppressed as a whole of the rotor 3 even when the skew structure is adopted for the rotor 3. For this reason, it is possible to provide a high-performance rotating electrical machine 1 that can reduce torque ripple while ensuring a desired torque.

(Second Embodiment)
Next, the second embodiment will be described based on FIGS. 5 and 6 with reference to FIG.
FIG. 5 is a diagram schematically showing two permanent magnets 211 on the same axis, and corresponds to FIG. 4 described above.
Here, the difference between the first embodiment and the second embodiment is that the location of the high coercive force processing unit 14 applied to the permanent magnet 11 of the first embodiment and the second embodiment. It is in the point from which the location of the high coercive-force process part 14 given to the permanent magnet 211 of a form differs (the same also about the following embodiment).

  More specifically, as shown in FIG. 5, the permanent magnet 211 of the second embodiment includes an end surface 211 a of the permanent magnet 211 facing the overlapping surface 8 a (see FIG. 2) of the rotor cores 8. The high coercive force processing unit 14 is applied to all outer peripheral surfaces except the end surface 211b on the opposite side.

A specific method for manufacturing such a permanent magnet 211 will be described.
That is, first, as shown in FIG. 6, a permanent magnet 211 having the same length H2 as the height H1 (see FIG. 2) in the central axis O direction in which two rotor cores 8 are stacked is prepared. The high coercive force processing unit 14 is applied to the entire outer surface of the substrate. The process of applying the high coercive force processing unit 14 is the same as that in the first embodiment.

  Subsequently, the permanent magnet 211 is cut in half in the height direction H2 and divided into two. And it assembles | attaches to the rotor core 8 so that the surface on the opposite side to the cut surface 211c of each permanent magnet 211 divided into 2 may overlap. That is, the end surface 211b on the side opposite to the end surface 211a of the permanent magnet 211 and not subjected to the high coercive force processing unit 14 is a cut surface 211c.

  Therefore, according to the second embodiment described above, the same effects as those of the first embodiment described above can be obtained. In addition, since the two permanent magnets 211 that can be assembled to each of the laminated rotor cores 8 can be manufactured from one permanent magnet 211, the manufacturing cost of the rotor 3 is reduced. can do.

(Third embodiment)
Next, the third embodiment will be described based on FIG. 7 with reference to FIG.
FIG. 7 is a diagram schematically showing two permanent magnets 311 on the same axis, and corresponds to FIG. 4 described above.
As shown in the figure, the permanent magnet 311 of the third embodiment has a high coercive force processing unit only on the end surface 311a of the permanent magnet 311 facing the overlapping surface 8a of the rotor cores 8 (see FIG. 2). 14 is given.

Examples of the method of applying the high coercive force processing unit 14 only to the end surface 311a of the permanent magnet 311 include the following methods.
First, a mask is applied to all outer surfaces except the end surface 311 a of the permanent magnet 311. Then, with this mask applied, a heavy rare earth such as dysprosium (Dy) or terbium (Tb) is applied or deposited on the surface of the permanent magnet 311 to form a heavy rare earth film. Thereafter, the mask is removed, and the heavy rare earth film is diffused in the permanent magnet 311. Thereby, the high coercive force processing unit 14 can be applied only to the end surface 311 a of the permanent magnet 311.

  Therefore, according to the third embodiment described above, the same effects as those of the first embodiment described above can be obtained. In addition, when the high coercive force processing unit 14 of the permanent magnet 311 is applied, the minimum necessary part of the high coercive force processing unit 14 (the location where the permanent magnet 311 is easily demagnetized, that is, the vicinity of the overlapping surface 8a of the rotor cores 8). Only) is provided with a high coercive force processing section 14. For this reason, the manufacturing cost of the permanent magnet 311 can be further reduced.

(Fourth embodiment)
Next, a fourth embodiment will be described based on FIG.
FIG. 8 is a diagram schematically showing four permanent magnets 411 on the same axis, and corresponds to FIG. 4 described above.
As shown in the figure, in the fourth embodiment, the rotor 403 is provided with two rotor cores 8, and these four rotor cores 8 are in the direction of the central axis O (not shown in FIG. 8). It is laminated along. Of the four rotor cores 8, the two rotor cores 8 at the center in the central axis O direction are not shifted in relative position in the circumferential direction, and are end faces of two permanent magnets 411 facing in the central axis O direction. All of 411a overlap.

  On the other hand, of the four rotor cores 8, the two rotor cores 8 arranged on the outer side in the central axis O direction are the two rotor cores 8 arranged in the center axis O direction center of these rotor cores 8. The rotor core 8 is arranged with a predetermined angle shift in the circumferential direction. Accordingly, the rotor 3 as a whole (the permanent magnet 411 as a whole) has a skew structure.

  In such a case, the high coercive force processing unit 14 is not applied to the end surface 411a of the permanent magnet 411 where the overlapping surface 8a of the rotor cores 8 is not displaced in the circumferential direction. This is because the area where the end faces 411a of the permanent magnets 411 are in contact with each other is the same as the cross-sectional area along the radial direction of each permanent magnet 11, and the demagnetizing magnetic flux by the stator 2 is not particularly easy to pass.

For this reason, the following manufacturing method can be employ | adopted for the permanent magnet 411 assembled | attached to the two rotor cores 8 of the center axis | shaft O direction center, for example.
That is, as shown in FIG. 6 of the second embodiment described above, first, on the outer surface of the permanent magnet 211 having the same length H2 as the height H1 in the central axis O direction in which two rotor cores 8 are stacked. What gave the high coercive-force processing part 14 is divided into two. Then, without changing the orientation as it is, the permanent magnet 411 of the fourth embodiment is assembled to the two rotor cores 8 in the center of the central axis O direction.

On the other hand, the following manufacturing method can be adopted for the permanent magnet 411 outside the central axis O direction arranged with a predetermined angle shift in the circumferential direction with respect to the rotor core 8, for example.
That is, as shown in FIG. 6 of the second embodiment described above, first, the permanent magnet 211 is divided into two. Thereafter, the direction of the permanent magnet 211 is changed so that the surface opposite to the cut surface 211 c of the permanent magnet 211 overlaps the permanent magnet 411 of the other rotor core 8. Then, the permanent magnets 411 of the fourth embodiment are assembled to the two rotor cores 8 on the outer side in the central axis O direction.
Thus, the permanent magnet 411 on the outer side in the central axis O direction is the end surface opposite to the overlapping surface 8a of the rotor cores 8 (the end surface on which the high coercive force processing unit 14 is not applied, the outer side in the central axis O direction). The exposed end surface 411b is a cut surface 411c.

  Therefore, according to the above-described fourth embodiment, the same effects as those of the above-described second embodiment can be obtained. Further, the rotational torque of the rotating electrical machine 1 can be improved by the amount of the four rotor cores 8 stacked.

In addition, the rotor 3403 of the above-mentioned embodiment demonstrated the case where the rotor core 8 was laminated | stacked two or four. However, the present invention is not limited to this, and three or five or more may be stacked. Desirably, an even number of rotor cores 8 are laminated. By setting the number of laminated rotor cores 8 to an even number, the effects as in the second embodiment and the fourth embodiment can be obtained.
When a plurality of rotor cores 8 are stacked, at least one of two permanent magnets arranged in the direction of the central axis O and shifted by a predetermined angle in the circumferential direction is opposite to the end surfaces facing each other. It is desirable that the end surface on the side (end surface exposed to the outside in the central axis O direction) be a cut surface.

  Furthermore, in the above-described embodiment, the case where the rotor core 8 is configured to form the convex poles of eight magnetic poles has been described. Further, the rotor iron core 8 has been described with respect to the case where one magnetic pole is formed by arranging two permanent magnets 11 to 411 in a V shape with the radially outer side viewed from the central axis O direction. However, the present invention is not limited to this, and the configuration of the permanent magnets 11 to 411 described above can be employed in various types of rotating electrical machines with a built-in magnet.

  According to at least one embodiment described above, even if the skew structure is adopted for the rotor 3, 403, the deterioration of the demagnetization resistance performance of the permanent magnets 11 to 411 as a whole is suppressed. it can. For this reason, it is possible to provide a high-performance rotating electrical machine 1 that can reduce torque ripple while ensuring a desired torque.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Rotary electric machine, 3,403 ... Rotor, 8 ... Rotor core, 8a ... Overlapping surface 11, 21, 211, 311, 411 ... Permanent magnet, 11a, 211a, 311a, 411a ... End face, 211c, 411c ... Cutting Surface, 13 ... shaft, 14 ... high coercive force processing section, O ... center axis (rotation axis)

Claims (3)

A shaft that rotates about the axis of rotation;
A plurality of rotor cores fixed to the shaft and stacked along the rotation axis;
A plurality of permanent magnets embedded in each of the plurality of rotor cores;
With
Among the plurality of permanent magnets, at least two permanent magnets arranged in the rotation axis direction are arranged with a predetermined angle shifted in the circumferential direction,
A rotor in which a film formed by performing a high coercive force process having a higher coercive force than the inside of each of the permanent magnets is formed on end surfaces facing each other of the permanent magnets shifted by a predetermined angle. The at least one of the two permanent magnets arranged in the rotation axis direction and shifted by a predetermined angle in the circumferential direction has an end surface opposite to an end surface facing each other as a cut surface. Rotor. The number of the plurality of rotor cores is set to an even number,
3. The rotor according to claim 2, wherein the permanent magnet located on the outer side in the rotational axis direction has an end surface opposite to an end surface facing the other permanent magnet in the rotational axis direction as the cut surface.

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