JPH10210692A - Permanent magnet rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a permanent magnet rotor for motor provided, on the outer circumference thereof, with a nonmagnetic metal cover for preventing the fragment of the magnet from being scattered, in which the motor efficiency is enhanced by reducing eddy current loss generated in the nonmagnetic metal cover without lowering the quality. SOLUTION: A nonmagnetic metal cover for preventing a permanent magnet 4 from being scattered has a double structure, wherein double nonmagnetic metal covers 1a, 1b are provided, respectively, with slits 5a, 5b which do not overlap each other. Since a fragment of the permanent magnet can be prevented from being scattered through the slit without lowering strength, internal eddy current loss can be reduced without sacrificing the quality resulting in the enhancement of motor efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet rotor.

[0002]

2. Description of the Related Art In recent years, in order to meet the demand for energy saving of electric motors, permanent magnet electric motors having permanent magnets in rotors have been increasingly used in place of conventional induction motors for the purpose of improving efficiency. ing. Further, the rotor generally has a configuration in which a permanent magnet is mounted on an outer peripheral portion of a yoke iron core, and a cover is provided on the outer peripheral portion of the permanent magnet for the purpose of preventing scattering of the permanent magnet. Metallic and nonmetallic cover materials for preventing the permanent magnets of the rotor of the permanent magnet motor from scattering are conceivable. Among these, for the non-metallic cover material, for example, glass bind or the like is conceivable, but the strength is almost equal to the metal material, but there is a temperature limit such that the rotor used cannot be shrink-fitted by the adhesive used. In addition, there are drawbacks such as that it takes much time for the bonding process of the binding material and the like. In addition, general plastics other than glass binding are easy to shape, so there is no need to use an adhesive and the process can be simplified.However, since the strength is inferior to metal covers, they are used as cover materials to prevent the scattering of permanent magnets. It could not be hired alone.

On the other hand, a cover made of a metal material has an advantage that it can withstand high temperatures and has a high productivity, but on the other hand, since the material is conductive, a loss due to eddy current is generated and the efficiency of the motor is reduced. There was a disadvantage. In order to compensate for this disadvantage, it is conceivable to use a material having low conductivity, for example, titanium or chromium, but the material cost is high and is not practical. Although it is conceivable to reduce the thickness of the metal material, there is a drawback such that the scattering prevention strength of the permanent magnet is reduced. Further, as disclosed in Japanese Patent Application Laid-Open No. Sho 58-46856, a slit is provided in the non-magnetic metal cover in a direction perpendicular to the axial direction of the rotating shaft and along the circumferential direction of the cover. There is a means for reducing the eddy current loss in the metal cover by adopting the above structure. In addition, there is a means for reducing the eddy current loss in the metal cover by providing a concave portion on the outer periphery of the nonmagnetic metal cover instead of the slit.

Hereinafter, a conventional permanent magnet rotor having a non-magnetic metal cover will be described. FIG. 3 is a perspective view showing a configuration of a permanent magnet rotor in which a slit is provided in a conventional non-magnetic metal cover, and FIG. 4 is a partially enlarged view of the non-magnetic metal cover of FIG. In FIG. 3, 1 is a non-magnetic metal cover, 2 is a rotor shaft, and 3 is a yoke core. Reference numeral 4 denotes a permanent magnet, and 5 denotes a slit. A rotor shaft 2, a yoke core 3 arranged on the outer periphery of the rotor shaft 2, a bow-shaped permanent magnet 4 arranged on the outer periphery of the yoke core 3, and an outer periphery of the permanent magnet 4. A rotor is constituted by the non-magnetic metal cover 1, and the rotor is formed on the non-magnetic metal cover 1 in a direction perpendicular to the axial direction of the rotor shaft 2 and along a circumferential direction of the non-magnetic metal cover 1. The slits 5 are provided at regular intervals. By providing the slit 5 in this manner, the path of the eddy current flowing through the non-magnetic metal cover 1 is segmented, and as a result, the length of the path of the eddy current as a whole is increased, and the electric resistance is increased. The value of the eddy current loss becomes smaller.

FIG. 5 is a perspective view showing a configuration of a permanent magnet rotor in which a concave portion is provided in a conventional non-magnetic metal cover, and FIG. 6 is a partially enlarged view of the non-magnetic metal cover of FIG. By providing the concave portion 6 instead of the slit as shown in FIGS. 5 and 6, an effect similar to the case where the slit is provided is obtained, and the value of the eddy current loss is reduced.

[0006]

However, the above-mentioned conventional configuration has the following problems. When the slit 5 is provided in the non-magnetic metal cover 1, there is a high possibility that minute chipped fragments of the permanent magnet 4 generated at the time of assembling the rotor will fly out of the slit 5. In particular, when used for hermetic compressors, since the compression element portion is configured with a clearance of several microns, when a small chipped piece of the permanent magnet 4 enters the compressor element portion during assembly of the compressor. In such a case, there was a risk of causing a fatal failure that the compressor element part was locked.

When the concave portion 6 is provided in the non-magnetic metal cover 1, it is necessary to process the concave portion 6 with an accurate depth in the thin non-magnetic metal cover 1. As a result, the equipment cost and the processing cost increase, which is a factor of cost increase. Further, there is a problem that the effect of reducing the eddy current loss is smaller than the case where the slit 5 is provided.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a permanent magnet rotor that suppresses a decrease in quality and cost and improves the efficiency of a motor.

[0009]

In order to achieve the above object, a permanent magnet rotor according to the present invention comprises a non-magnetic material cover as a double non-magnetic metal cover, and the double non-magnetic metal cover has A plurality of slits are provided at positions that are orthogonal to the axial direction of the rotor shaft and do not overlap each other.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a yoke core disposed on the outer periphery of a rotor shaft and forming a rotor magnetic path, and a permanent magnet disposed on the outer periphery of the yoke core. And a non-magnetic material cover arranged on the outer periphery of the permanent magnet, wherein the non-magnetic material cover is a double non-magnetic metal cover, and the double non-magnetic metal cover is A plurality of slits are provided at positions that are orthogonal to the axial direction of the rotor shaft and do not overlap each other. Even if a plurality of slits are provided in one of the non-magnetic metal covers in a direction orthogonal to the axial direction of the rotor shaft, the other non-magnetic metal cover closes the slits, so that the fine permanent magnets generated during the assembly of the rotor are fine Chipped fragments can be prevented from jumping out of the slit.
Further, the processing cost of the non-magnetic metal cover can be reduced as compared with the case where the concave portion is provided, and the effect of reducing the eddy current loss is great.
Further, since the non-magnetic metal cover is doubled, the scattering prevention strength of the permanent magnet does not decrease and the eddy current loss can be reduced even if the thickness of the non-magnetic metal cover is reduced. as a result,
It is possible to suppress a decrease in quality and an increase in cost, and to improve the efficiency of the electric motor.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will now be described with reference to FIGS.
This will be described with reference to FIG.

FIG. 1 is a perspective view of a permanent magnet rotor according to an embodiment of the present invention, and FIG. 2 is a partially enlarged sectional view of the nonmagnetic metal cover of FIG. In FIG. 1, 1a and 1b are non-magnetic metal covers, and 2 is a rotor shaft. Reference numeral 3 denotes a yoke core, and reference numeral 4 denotes a permanent magnet. 5a and 5b are slits. The non-magnetic metal cover has a double structure of 1a and 1b, and the double non-magnetic metal cover 1a and 1b has a plurality of slits 5a and 5b in a direction orthogonal to the axial direction of the rotor shaft. Provided and its double non-magnetic metal cover 1
The slits 5a and 5b provided in the a and 1b are provided at positions where they do not overlap with each other.

As described above, according to the present invention, the non-magnetic metal cover has a double structure of 1a and 1b, and the two non-magnetic metal covers 1a and 1b are respectively provided in the direction orthogonal to the axial direction of the rotor shaft 2. By providing a plurality of slits 5a and 5b and preventing the slits of the groups a and b from overlapping each other, the nonmagnetic metal covers 1a and 1b are provided with a plurality of slits in a direction orthogonal to the axial direction of the rotor shaft 2. Even with slits,
Since the non-magnetic metal covers 1a and 1b of each other close the slit of the other non-magnetic metal cover, it is possible to prevent the minute chipped pieces of the permanent magnet 4 generated during the assembly of the rotor from jumping out of the slit. Further, the processing cost of the non-magnetic metal cover can be reduced as compared with the case where the concave portion is provided, and the effect of reducing the eddy current loss is great. In addition, the non-magnetic metal cover 1a,
Since 1b has a double structure, the nonmagnetic metal covers 1a, 1
Even if the thickness of b is reduced, the scattering prevention strength of the permanent magnet 4 does not decrease and eddy current loss can be reduced. As a result, it is possible to suppress a decrease in quality and cost, and to improve the efficiency of the electric motor.

[0014]

As described above, according to the present invention, the non-magnetic metal cover is doubled, and a plurality of slits are provided in each of the double non-magnetic metal covers in a direction orthogonal to the axial direction of the rotor shaft. In addition, by preventing the slits provided in the two non-magnetic metal covers from overlapping each other, a permanent magnet rotor that improves the efficiency of the electric motor without lowering the quality can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view of a permanent magnet rotor according to an embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of the non-magnetic metal cover of FIG. 1;

FIG. 3 is a perspective view of a conventional permanent magnet rotor in which a slit is provided in a nonmagnetic metal cover.

FIG. 4 is a partially enlarged sectional view of the non-magnetic metal cover of FIG. 3;

FIG. 5 is a perspective view of a conventional permanent magnet rotor having a recess formed in a nonmagnetic metal cover.

6 is a partially enlarged cross-sectional view of the non-magnetic metal cover of FIG.

[Explanation of symbols]

 1, 1a, 1b Nonmagnetic metal cover 2 Rotor shaft 3 Yoke core 4 Permanent magnet 5 Slit 6, 6a, 6b Recess

Claims (1)

[Claims] 1. A yoke core disposed on the outer periphery of a rotor shaft and forming a rotor magnetic path, a permanent magnet disposed on the outer periphery of the yoke core, and a non-magnetic material disposed on the outer periphery of the permanent magnet A permanent magnet rotor having a cover, wherein the non-magnetic material cover is a double non-magnetic metal cover, and the double non-magnetic metal cover is provided on each of the non-magnetic metal covers in a direction perpendicular to the axial direction of the rotor shaft and mutually. A permanent magnet rotor characterized in that a plurality of slits are provided at positions where they do not overlap.