JP2005354806A - Rotor for electric motor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotor for an electric motor capable of realizing both suppression in an eddy current loss and reduction in a manufacturing cost. <P>SOLUTION: The rotor 10 for an electric motor is largely constituted of a rotor shaft 11, and a rotor iron core 12 which is integrally fitted to the rotor shaft 11 and serves as the magnetic field generating source of a magnetic flux. The rotor iron core 12 is constituted of a combination of a plurality of rotor iron core division pieces 12a, and is formed by continuously arranging the division pieces in the axial direction of the rotary shaft 11. The structure of the rotor iron core division pieces 12a is formed of laminated iron cores 13 formed by laminating a plurality of magnetic steel plates in the axial direction, structural steels 14 having a substantially the same cross-sectional shape as the laminated iron cores 13, a plurality of openings 15 which are arranged in the circumferential direction of the laminated iron cores 13 and the structural steels 14 at given intervals and are formed opening in the axial direction, and magnets 16 each being inserted into the plurality of openings 15. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rotor for an electric motor and a method for manufacturing the rotor for an electric motor, and in particular, the rotor for an electric motor and the rotation for the electric motor that can realize suppression of eddy current loss and reduction of manufacturing cost due to high rotation. The present invention relates to a child manufacturing method.

  A magnet-embedded synchronous motor (hereinafter referred to as an IP motor) is a motor that uses both a torque due to a magnet and a torque due to reluctance of an electromagnetic steel sheet. Since the rotor and stator used in this IP motor are both formed by laminating punched steel plates, the manufacturing yield is extremely low at about 45%.

JP 09-019090 A JP 2003-189514 A

  In contrast to the conventional techniques as described above, in recent years, methods for yield improvement and cost reduction such as split type and spiral winding have been implemented on the stator side of the IP motor. However, on the rotor side, due to problems such as strength, the current situation is that a method with a poor yield of punching and laminating steel sheets as before has to be taken.

  Overcoming this problem has become an important issue, coupled with the demand for smaller and higher speeds currently required for motors. That is, as the motor speed increases, eddy current loss increases and countermeasures against thermal demagnetization are required.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an electric motor capable of realizing both suppression of eddy current loss and reduction of manufacturing cost accompanying high rotation. It is providing the manufacturing method of the rotor for motors, and the rotor for motors.

  A rotor for an electric motor according to the present invention includes a rotor shaft and a rotor core that is integrally fixed to the rotor shaft and serves as a field flux generation source, and includes a plurality of magnetic steel plates in the axial direction. A laminated iron core formed by laminating, a structural steel having substantially the same cross-sectional shape as the laminated iron core, and disposed in a circumferential direction of the laminated iron core and the structural steel via a predetermined interval, and an axial direction A rotor core split piece formed by a plurality of openings formed by being opened to each other and magnets respectively inserted into the plurality of openings, and the rotor core is divided into the rotor cores A plurality of pieces are combined in the axial direction of the rotor shaft.

  Further, in the rotor for an electric motor according to the present invention, the magnetic steel plate closes the opening on the surface where the rotor core split pieces contact each other, and the opening on the surface forming both ends of the rotor core. When the end plate made of a nonmagnetic material is closed, it is preferable that the magnet is fixedly inserted so as not to contact between the rotor core divided pieces combined in the axial direction of the rotor shaft. It is.

  The method for manufacturing a rotor for an electric motor according to the present invention includes a plurality of magnetic steel plates arranged in the circumferential direction at predetermined intervals and having a plurality of openings formed by opening in the axial direction. A step of laminating and forming a laminated core, a structural steel having substantially the same cross-sectional shape as the laminated core, and the laminated core are combined in the axial direction, and a magnet is inserted into each of the plurality of openings. Forming a rotor core split piece by combining a plurality of the rotor core split pieces in the axial direction to form a rotor core serving as a field magnetic flux generation source, and the rotor core with respect to the rotor shaft. And fixing together.

  Further, in the method for manufacturing a rotor for an electric motor according to the present invention, on the surface where the rotor core split pieces are in contact with each other, the opening is closed with a magnetic steel plate, and on both surfaces of the rotor core, By closing the opening with an end plate made of a non-magnetic material, the magnet is fixedly inserted so as not to contact between the rotor core split pieces combined in the axial direction of the rotor shaft. It is preferable to do so.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the rotor for motors and the rotor for motors which can implement | achieve both suppression of the eddy current loss accompanying high rotation and reduction of manufacturing cost can be provided.

  As a result of diligent efforts to solve the problems of the prior art, the inventor has obtained various knowledge about the characteristics of the IP motor.

[Low-cost approach]
First, in order to reduce costs, we examined the use of structural steel by reducing the amount of punched electrical steel sheets with poor production yield that were conventionally used for rotor cores.

  FIG. 1 is a diagram showing an iron loss deterioration rate when the material of the rotor core is changed to a structural steel plate. In addition, what laminated | stacked only the 2.0 mm-thick electromagnetic soft iron plate is used for the structural steel plate at this time. As a result, as is apparent from FIG. 1, in the rotor core using only the structural steel plate, the iron loss is about three times that in the case of manufacturing with the electromagnetic steel plate, and the motor efficiency is greatly deteriorated. It could be confirmed. From this result, it was confirmed that it is not preferable to form the rotor core with only the structural steel because the motor efficiency is deteriorated.

  The inventor who has obtained the above knowledge next tried to realize a rotor core in which two kinds of materials of electromagnetic steel plate and structural steel were combined. First, the magnetic characteristics of the magnet to be embedded in the rotor of the IP motor were confirmed. FIG. 2 is a diagram showing DC magnetic characteristics of Nd—Fe—B magnets and various structural steels. FIG. 2 reveals that the residual magnetic flux density of the Nd—Fe—B magnet fluctuates around 1.2 T with a width of about 0.1 T during the rotation of the rotor. Further, it was confirmed that the DC magnetic characteristics of the Nd—Fe—B magnet did not change greatly even when the rotation speed of the rotor was increased.

  On the other hand, with respect to the DC magnetic characteristics of structural steel, cold-rolled steel sheets with a large rise in magnetic flux density are the best, and in the following order, pure iron (ELCH2), electromagnetic steel sheets, low carbon steel, medium carbon steel, SUS404C. I found out. That is, it became clear that these structural steels may be selected according to desired motor characteristics and cost.

  Furthermore, the DC magnetic characteristics were also confirmed when the rotor core had a multilayer structure of electromagnetic steel sheets and structural steel. FIG. 3 is a diagram showing the stacking ratio dependence of the DC magnetic characteristics when the rotor core has a two-layer structure. From the results shown in FIG. 3, it was confirmed that the DC magnetic characteristics can be controlled by selecting the combination of the electrical steel sheet and the structural steel used for the rotor core and the lamination ratio.

  From the above results, the inventor can suppress the deterioration of iron loss to a minimum by optimally selecting the combination of the magnetic steel sheet and the structural steel used for the rotor core and the structural ratio, and the desired motor efficiency can be reduced. Confirmed that it was feasible.

  Furthermore, the inventor has found that the lamination ratio is important in adopting a multilayer structure of electromagnetic steel sheet and structural steel. FIG. 4 is a diagram showing the influence of the lamination ratio on the iron loss, and is a diagram showing the result of comparing the two-layer structure and the three-layer structure. As is clear from FIG. 4, there was no difference in iron loss between the two-layer structure and the three-layer structure. Therefore, it became clear that the lamination ratio plays an important role for iron loss. That is, it was confirmed that the rate of deterioration of iron loss can be flexibly controlled by changing the lamination ratio of the electromagnetic steel sheet and the structural steel.

FIG. 3 shows the iron loss value per unit weight. In a general motor, the weight ratio of the stator and the rotor is 2: 1. If the weight is y, the motor iron loss W is roughly calculated.
(Equation 1)
W = 2yx + yx = 3yx (1)
It becomes.

Here, when applied to the present invention, for example, when the rotor is manufactured with a lamination ratio of the electromagnetic steel sheet (α) and the structural steel (β) of 1: 1, the iron loss when the rotor is manufactured using only the electromagnetic steel sheet is 1.6. The motor iron loss is
(Equation 2)
W = 2yx + 1.6yx = 3.6yx (2)
(See FIG. 4), it can be seen that the comparison between the equations (1) and (2) is only an increase of 20%.

In the case of small and high-speed motors used in electric vehicles, depending on the physique and operating range, the lamination ratio of electromagnetic steel sheet (α) and structural steel (β)
(Equation 3)
0 ≦ β / α <1.5 (3)
Is desirable.

  In addition, in the prior art, there is a technique that discloses a technique of adopting a multilayer structure of electromagnetic steel plates and structural steels for the rotor core (see Patent Documents 1 and 2 above). However, the prior arts shown in Patent Documents 1 and 2 simply use structural steel as a part of the rotor core from the viewpoint of cost reduction, and optimize the motor efficiency and the lamination ratio. Note that this is a technology that completely ignores.

[Eddy current loss suppression approach]
Next, for the suppression of eddy current loss, the magnet was divided as a countermeasure against thermal demagnetization. This is because by dividing the magnet, the heat dissipation characteristics are improved and the loss in the magnet can be reduced.

[Specific Embodiment]
Based on the knowledge obtained by the above examination, the inventor has created a rotor for an electric motor that can realize both suppression of eddy current loss and reduction of manufacturing cost. Hereinafter, a specific structure of the electric motor rotor according to the present embodiment will be described with reference to FIGS. 5A and 5B. The following embodiments do not limit the invention according to each claim, and all combinations of features described in the embodiments are not necessarily essential to the solution means of the invention. .

  FIG. 5A is a schematic diagram of an electric motor in which the electric motor rotor according to the present embodiment is used. Moreover, FIG. 5B is a longitudinal cross-sectional view which shows the (AA) cross section in FIG. 5A.

  The electric motor rotor 10 according to this embodiment is roughly composed of a rotor shaft 11 and a rotor core 12 that is integrally fixed to the rotor shaft 11 and serves as a field magnetic flux generation source.

  A characteristic feature of the present embodiment is that the rotor core 12 is constituted by a combination of a plurality of rotor core split pieces 12a. The plurality of rotor core split pieces 12 a are continuously installed in the axial direction of the rotor shaft 11 to form the rotor core 12. As a fixing method to the rotor shaft 11, welding, Known techniques such as caulking and press fitting can be employed.

  As the structure of the rotor core split piece 12a, a laminated iron core 13 formed by laminating a plurality of magnetic steel plates in the axial direction, a structural steel 14 having substantially the same cross-sectional shape as the laminated iron core 13, the laminated iron core 13 and the structure The steel plates 14 are arranged at predetermined intervals in the circumferential direction, and are formed by a plurality of openings 15 formed to be opened in the axial direction, and magnets 16 respectively inserted into the plurality of openings 15. Has been.

  The opening 15 is closed by the magnetic steel plate 13a on the surface where the rotor core split pieces 12a are in contact with each other, and the opening 15 is made of a nonmagnetic material on the surface forming both ends of the rotor core 12. The structure is closed. By adopting such a structure, the magnets 16 are fixedly inserted so as not to contact between the rotor core split pieces 12 a combined in the axial direction of the rotor shaft 11. In other words, the eddy current loss can be reduced by dividing the magnet 16, and the magnet 16 that can withstand high rotation can be fixed.

  Further, when the magnet 16 is fixed, it is preferable that the magnet 16 is fitted into the opening 15 together with the resin 18. This is because the resin 16 can reliably fix the magnet 16 by filling the gap between the opening 15 and the magnet 16.

  Incidentally, as a method for manufacturing the electric motor rotor 10 according to the present embodiment, a magnetic steel plate having a plurality of openings 15 that are arranged in the circumferential direction and are opened in the axial direction. Are laminated in the axial direction to form the laminated iron core 13, and the structural steel 14 having substantially the same cross-sectional shape as the laminated iron core 13 and the laminated iron core 13 are combined in the axial direction, and each of the plurality of openings 15 is combined. Then, the rotor core split piece 12a is formed by inserting the magnet 16 therein. When fixing the magnet 16, it is preferable to fit the opening 16 together with the resin 18. On the surface where the rotor core split pieces 12a are in contact with each other, the opening 15 is closed by the magnetic steel plate 13a, and on the surface forming both ends of the rotor core 12, the opening 15 is made of a nonmagnetic material. To close.

  A plurality of rotor core split pieces 12 a are combined in the axial direction to form a rotor core 12 that serves as a field magnetic flux generation source, and the rotor core 12 is integrally fixed to the rotor shaft 11. As a method of fixing to the rotor shaft 11, known techniques such as welding, caulking, and press-fitting can be employed. In this manner, the electric motor rotor 10 according to the present embodiment can be manufactured.

  As mentioned above, although preferred embodiment of this invention was described, the technical scope of this invention is not limited to the range as described in the said embodiment. Various modifications or improvements can be added to the above embodiment. It is apparent from the description of the scope of claims that embodiments with such changes or improvements can be included in the technical scope of the present invention.

It is a figure which shows the iron loss deterioration rate at the time of changing the material of a rotor iron core into the structural steel plate. It is a figure which shows the direct-current magnetic characteristic of a Nd-Fe-B type magnet and various structural steel. It is a figure showing the lamination | stacking ratio dependence of a DC magnetic characteristic at the time of making a rotor core into 2 layer structure. It is a figure which shows about the influence which a lamination ratio has on an iron loss, and is a figure which shows the result of having compared the thing of a 2 layer structure, and the thing of a 3 layer structure. It is the schematic of the electric motor in which the rotor for electric motors which concerns on this embodiment is used. It is a longitudinal cross-sectional view which shows the (AA) cross section in FIG. 5A.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Rotor for motors, 11 Rotor shafts, 12 Rotor cores, 12a Rotor core split pieces, 13 Laminated cores, 13a Magnetic steel plates, 14 Structural steels, 15 Openings, 16 Magnets, 17 End plates, 18 Resins.

Claims (4)

A rotor shaft;
A rotor core fixed integrally with the rotor shaft and serving as a field magnetic flux generation source;
A rotor for an electric motor including
A laminated iron core formed by laminating a plurality of magnetic steel plates in the axial direction;
Structural steel having substantially the same cross-sectional shape as the laminated core;
A plurality of openings formed in the circumferential direction of the laminated iron core and the structural steel with a predetermined interval therebetween, and opened in the axial direction;
Magnets that are respectively inserted into the plurality of openings,
Having a rotor core split piece formed by
The rotor core is configured by combining a plurality of rotor core split pieces in the axial direction of the rotor shaft. The rotor for an electric motor according to claim 1,
On the surface where the rotor core split pieces contact each other, the magnetic steel plate closes the opening,
On the surfaces forming both ends of the rotor core, the end plate made of a non-magnetic material closes the opening,
The rotor for an electric motor, wherein the magnet is fixedly inserted so as not to contact between the rotor core divided pieces combined in the axial direction of the rotor shaft. A step of forming a laminated iron core by laminating a plurality of magnetic steel plates in the axial direction and arranged in the circumferential direction with a predetermined interval and having a plurality of openings formed in the axial direction;
A step of forming a rotor core split piece by combining structural steel having substantially the same cross-sectional shape as the laminated iron core and the laminated iron core in the axial direction, and inserting magnets into each of the plurality of openings. When,
Forming a rotor core as a field magnetic flux generation source by combining a plurality of the rotor core split pieces in the axial direction, and fixing the rotor core integrally to the rotor shaft;
The manufacturing method of the rotor for electric motors characterized by performing these. In the manufacturing method of the rotor for electric motors according to claim 3,
On the surface where the rotor core split pieces contact each other, the magnetic steel plate closes the opening,
On the surfaces forming both ends of the rotor core, by closing the opening by an end plate made of a nonmagnetic material,
A method of manufacturing a rotor for an electric motor, wherein the magnet is fixedly inserted so as not to contact between the rotor core divided pieces combined in the axial direction of the rotor shaft.

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