JP2004328859A - Method of manufacturing rotor of motor, and rotor of motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a rotor and the rotor which can achieve a high output of a motor. <P>SOLUTION: A rotor 20 has a rotor core 21 which is made by stacking disklike magnetic thin plates. Four slits 22, which are arranged at substantially equal intervals in the circumference and pass axially through itself, are made in this rotor core 21. A permanent magnet 23 is inserted into each slit 22. Then, the periphery of the rotor core 21 is pressed in the direction of the internal circumference of the rotor core 21 by a mold 30 which has smaller curvature than that of the periphery of the rotor core 21, whereby the section of the slit 22 positioned in the vicinity of the end of the permanent magnet 23 is plastically transformed lengthwise in the direction of the internal circumference, and the permanent magnet 23 directly contacts with the rotor core 21, and within the slit 22, the permanent magnet 23 is fixed to the rotor core 21. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
【Technical field】
The present invention relates to a rotor manufacturing method and a rotor that are preferable for use in a motor with embedded permanent magnets.
[0002]
[Background Art]
In a motor required to have a small size and high output, a rotor having a permanent magnet disposed inside a rotor core, and a stator having windings wound around an outer periphery of the rotor are provided. 2. Description of the Related Art A permanent magnet embedded motor (hereinafter simply referred to as an “IPM (Interior Permanent Magnet) motor”) that realizes a small size and high output by using a torque is known.
[0003]
In a rotor used in such an IPM motor, a slit hole having a cross section larger than that of a permanent magnet disposed inside the rotor is formed in a rotor core, and after the permanent magnet is inserted into the slit hole, an adhesive is solidified. Thus, the permanent magnet is fixed to the rotor core (for example, see Patent Document 1).
[0004]
However, in such a method of fixing the permanent magnet, since the adhesive layer is interposed between the slit hole formed in the rotor core and the permanent magnet, it is difficult for the magnetic flux from the permanent magnet to pass in the outer peripheral direction of the rotor core. Therefore, the output of the IPM motor cannot be increased.
[0005]
Further, in such a fixing method, the heat conductivity of the adhesive layer interposed between the slit hole and the permanent magnet is lower than that of the rotor core, so that the heat generated by the permanent magnet is less likely to be transferred to the rotor core, and the permanent magnet is not removed. Because of poor thermal properties, the permanent magnet was demagnetized during high-power operation of the IPM motor, and it was necessary to limit the output.
[0006]
[Patent Document 1]
JP-A-2002-58185
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a rotor manufacturing method and a rotor capable of increasing the output of an electric motor.
[0008]
In order to achieve the above object, according to the present invention, there is provided a method for manufacturing a rotor in which permanent magnets are arranged in magnet insertion holes formed in a rotor core, which are used in a permanent magnet embedded type electric motor. Inserting the permanent magnet into a magnet insertion hole of the rotor core, and pressing an outer peripheral surface of the rotor core so as to partially deform the magnet insertion hole; And a step of fixing the magnet.
[0009]
To achieve the above object, according to the present invention, a permanent magnet is used in an electric motor with embedded permanent magnets, a rotor in which permanent magnets are arranged in magnet insertion holes formed in a rotor core, An outer peripheral surface of the rotor core is pressed, a part of the magnet insertion hole is deformed, and a rotor is provided in which the rotor core and the permanent magnet are fixed.
[0010]
According to the present invention, in a rotor used for a permanent magnet embedded type electric motor, a permanent magnet is inserted into a magnet insertion hole formed in the rotor core, and then the outer peripheral surface of the rotor core is pressed in an inner peripheral direction. Then, the rotor core and the permanent magnet are fixed by partially deforming the magnet insertion hole.
[0011]
As a result, the rotor core comes into direct contact with the permanent magnet inserted into the magnet insertion hole, and the permeability of the magnetic flux from the permanent magnet to the outer peripheral direction of the rotor core is improved. It becomes possible to plan.
[0012]
In addition, the direct contact between the permanent magnet and the rotor core improves heat transfer from the permanent magnet to the rotor core, and improves the heat removal of the permanent magnet. Demagnetization can be prevented, and the output of the motor can be increased.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0014]
FIG. 1 is a cross-sectional view of the IPM motor according to the first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1, FIG. 3 is an enlarged view of a part III of FIG. FIGS. 4A and 4B are diagrams illustrating a method of manufacturing a rotor used in the IPM motor according to the first embodiment of the present invention, wherein FIG. 4A illustrates a state before pressing, and FIG. It is.
[0015]
First, the structure of an IPM motor using a rotor manufactured by the method according to the present embodiment will be described.
[0016]
As shown in FIGS. 1 and 2, the IPM motor 1 according to the present embodiment includes a motor cover 2 including a housing 3 and first and second brackets 4 and 5, and the first and second brackets 4 and 4. 5, a shaft 7 rotatably supported by bearings 6 attached to the motor 5, a stator 10 fixed to the inner peripheral surface of the housing 3 of the motor cover 2, and a gap fixed to the outer periphery of the shaft 7. A rotor (rotor) 20 is provided rotatably relative to the stator 10 with an air gap therebetween, and has a permanent magnet 23 embedded therein.
[0017]
The stator 10 of the IPM motor 1 has 24 teeth 11 projecting toward the inside of an annular shape and having slots formed therebetween, and each tooth 11 is wound with a winding 12. Have been.
[0018]
The rotor 20 of the IPM motor 1 has a rotor core (rotor core) 21 formed by laminating disk-shaped magnetic thin plates made of, for example, a silicon steel plate. The rotor core 21 has, at its center, through holes into which the shaft 7 is inserted, formed in the axial direction, and is arranged at substantially equal intervals in the circumferential direction, and is formed along the axial direction. Four slit holes (magnet insertion holes) 22 that penetrate and have a larger cross-sectional shape than the inserted permanent magnet 23 are formed.
[0019]
Four (two pairs) of permanent magnets 23 are inserted into each of the slit holes 22. The permanent magnets 23 have a rectangular cross section of the permanent magnets 23 such that the long sides, which are the magnetic poles, face the inner peripheral side, and that the adjacent permanent magnets 23 have mutually different polarities. 21 are arranged inside.
[0020]
As a material used for the permanent magnet 23, for example, a neodymium magnet is preferable from the viewpoint of rust prevention. Further, since the permanent magnet 23 is already magnetized and is inserted into the slit hole 22 while being in contact with the rotor core 21 due to the magnetic attraction of the permanent magnet 23, for example, nickel It is preferable to improve the strength by performing a surface treatment such as plating or epoxy coating, to prevent the permanent magnet 23 from cracking, chipping and peeling, and to perform rust prevention.
[0021]
Further, as shown in FIG. 3, the outer peripheral surface of the rotor core 21 in which the permanent magnet 23 is inserted is pressed and plastically deforms, so that a concave portion 24 is formed in the outer peripheral surface of the rotor core 21 in the longitudinal direction. Have been. Due to this plastic deformation, the portion of the slit hole 22 located near the end of the permanent magnet 23 is more specifically, the portion of the slit hole 22 located near the corner in the cross section with respect to the longitudinal direction of the permanent magnet 23. Are deformed to the inner peripheral side of the rotor core 21 in the longitudinal direction, and the permanent magnet 23 is in contact with the inner wall surface of the slit hole 22 of the rotor core 21 so that the permanent magnet 23 is fixed to the rotor core 21.
[0022]
In the IPM motor 1 configured as described above, when a current flows through the winding 12 wound on the stator 10, a rotating magnetic field is generated, and a torque is generated between the stator 10 and the rotor 20 by the rotating magnetic field. Thus, the rotor 20 fixed to the shaft 7 rotates relatively to the stator 10. The torque generated at this time is generated by the magnet torque due to the repulsion and attraction of the winding 12 of the stator 10 and the permanent magnet 23 of the rotor 20 and the difference between the magnetic permeability of the permanent magnet 23 and the magnetic permeability of the rotor core 21. And reactance torque.
[0023]
Next, a method of manufacturing the rotor having the above structure will be described.
[0024]
First, the surface-treated permanent magnet 23 is inserted into the slit hole 22 formed in the laminated rotor core 21.
[0025]
Next, as shown in FIGS. 4A and 4B, a portion of the slit hole 22 located near the end of the permanent magnet 23 is more specifically formed by a mold 30 having a curved press surface. Specifically, the outer circumferential surface of the rotor core 21 is moved in the inner circumferential direction of the rotor core 21 so that the portion of the slit hole 22 located near the corner in the cross section with respect to the longitudinal direction of the permanent magnet 23 is plastically deformed in the longitudinal direction. Press toward.
[0026]
Here, the press surface of the mold 30 has a smaller curvature than the circumferential curvature of the outer peripheral surface of the rotor core 21. For example, in the present embodiment, as shown in FIG. 4 (A), the pressing surface of the die 30 has a radius r _P around the center O _P, and has a curved surface having a width W _P. In contrast, the outer peripheral surface of the rotor core 21 has a circumferential curved surface of a radius r _R around the center O _R, slits 22 which the permanent magnet 23 is inserted has a width W _R. The radius r _P of the press surface of the mold 30 is smaller than the radius r _R of the outer peripheral surface of the rotor core 21 (r _P <r _R ), and the width W _P of the press surface of the mold 30 is equal to the slit hole. in 22 the width _{W R} that is substantially of which is substantially the same _{(W P} ≒ _W R).
[0027]
When the mold 30 presses the outer peripheral surface of the rotor core 21 corresponding to the slit hole 22 toward the inner peripheral direction, as shown in FIG. Is positively pressed against the outer periphery of the rotor core 21 to plastically deform the outer peripheral surface of the rotor core 21, and the concave portion 24 is efficiently formed on the outer peripheral surface of the rotor core 21 in the longitudinal direction.
[0028]
In addition, due to this pressing, the portion of the slit hole 22 located near the corner in the cross section with respect to the longitudinal direction of the permanent magnet 23 is plastically deformed in the inner circumferential direction over the longitudinal direction, and the permanent magnet 23 directly contacts the rotor core 21. At the same time, the permanent magnet 23 is fixed to the rotor core 21 inside the slit hole 22.
[0029]
Next, the rotor core 21 is rotated by an angle α corresponding to one pole pitch shown in FIG. 4A, and the outer peripheral surface of the rotor core 21 is pressed as shown in FIG. The process of forming the concave portion 24 of the surface and deforming a part of the slit hole 22 is repeated, and the other three permanent magnets 23 are fixed to the rotor core 21 so that the four permanent magnets 23 shown in FIGS. The rotor 20 in which two (two pairs) permanent magnets are embedded is manufactured.
[0030]
As described above, in the rotor according to the present embodiment, since the permanent magnet is fixed by deforming the slit hole of the rotor core, the rotor core comes into direct contact with the permanent magnet, and the magnetic flux from the permanent magnet to the outer peripheral direction of the rotor core is generated. Of the IPM motor can be improved.
[0031]
Further, the direct contact between the rotor core and the permanent magnet improves the heat transfer from the permanent magnet to the rotor core, and improves the heat removal property of the permanent magnet. Can be prevented, and the output of the IPM motor can be increased. In particular, by bringing the end of the permanent magnet, which generates a large amount of heat, directly into contact with the rotor core in the longitudinal direction, it is possible to effectively improve heat removal.
[0032]
Furthermore, since the concave portion is formed on the outer peripheral surface of the rotor core, the air in the air gap between the stator and the rotor is agitated by the concave portion along with the rotation by the torque, thereby improving the cooling efficiency of the IPM motor. I do.
[0033]
Further, in the rotor manufacturing method according to the present embodiment, a mold having a press surface having a curvature smaller than the curvature of the outer peripheral surface of the rotor core is used, and the vicinity of both ends of the press surface of the mold is positively applied to the outer peripheral surface of the rotor core. By pressing one part, the concave part of the outer peripheral surface of the rotor core can be formed by one mold, and a part of the slit hole can be surely pressed, so that the rotor according to the present embodiment can be efficiently and inexpensively manufactured. It becomes possible.
[0034]
Generally, in an IPM motor, a flux barrier (magnetic flux cut-off area) in which a hollow or aluminum or copper is cast is provided around a permanent magnet in order to prevent a short circuit of magnetic flux. On the other hand, in the present embodiment, by pressing when forming the concave portion on the outer peripheral surface of the rotor core, magnetostriction is generated in the rotor core around the concave portion, thereby preventing a short circuit of magnetic flux without providing a flux barrier. Becomes possible.
[0035]
Further, when a flux barrier is provided, the strength of the rotor core becomes a problem due to the thickness of the bridge portion which becomes thin between the flux barrier and the outer peripheral surface of the rotor core. There is no need to provide a barrier, and the strength of the rotor core does not decrease due to the thickness of the bridge portion. Further, since the portion where the permanent magnet is closest to the outer periphery of the rotor core is hardened by pressing, the strength is improved as compared with the case where the thickness is the same.
[0036]
Further, in the rotor according to the present embodiment, the outer peripheral surface of the rotor core is pressed, the slit hole is deformed, and the permanent magnet is positioned and fixed with reference to the inner wall surface on the inner peripheral side of the slit hole. Problems such as unbalance and torque ripple are also eliminated.
[0037]
The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an IPM motor according to a first embodiment of the present invention.
FIG. 2 is a sectional view taken along line II-II in FIG.
FIG. 3 is an enlarged view of a part III in FIG. 2;
FIG. 4 is a view showing a method of manufacturing a rotor used for the IPM motor according to the first embodiment of the present invention, FIG. 4 (A) shows a state before pressing, and FIG. 4 (B) FIG. 4 is a diagram showing a pressed state.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 IPM motor 2 motor cover 3 housing 4 first bracket 5 second bracket 6 bearing 7 shaft 10 stator 11 teeth 12 winding 20 rotor 21 rotor core 22 slit hole 23 ... permanent magnet 24 ... recess 30 ... mold

Claims (8)

A method for manufacturing a rotor in which permanent magnets are arranged in a magnet insertion hole formed in a rotor core, which is used for a permanent magnet embedded type electric motor,
Inserting the permanent magnet into a magnet insertion hole of the rotor core;
Pressing the outer peripheral surface of the rotor core so as to deform a part of the magnet insertion hole, and fixing the rotor core and the permanent magnet. The method for manufacturing a rotor according to claim 1, wherein a part of the magnet insertion hole is a part of the magnet insertion hole located near an end of the permanent magnet. In the step of pressing the outer peripheral surface of the rotor core,
3. The method for manufacturing a rotor according to claim 1, wherein the outer peripheral surface of the rotor core is pressed by a mold having a smaller curvature than the outer peripheral surface of the rotor core pressed. In the step of pressing the outer peripheral surface of the rotor core,
4. The method for manufacturing a rotor according to claim 2, wherein the outer peripheral surface of the rotor core is pressed so that a concave portion is formed on the outer peripheral surface of the pressed rotor core. A rotor in which permanent magnets are arranged in a magnet insertion hole formed in a rotor core, which is used for a permanent magnet embedded type electric motor,
A rotor in which the outer peripheral surface of the rotor core is pressed, a part of the magnet insertion hole is deformed, and the rotor core and the permanent magnet are fixed. The rotor according to claim 5, wherein a part of the magnet insertion hole is a portion of the magnet insertion hole located near an end of the permanent magnet. The rotor according to claim 5, wherein the outer peripheral surface of the rotor core is pressed by a mold having a smaller curvature than the outer peripheral surface of the rotor core pressed. The rotor according to claim 6, wherein a recess is formed on the outer peripheral surface of the pressed rotor core.

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