JPS6281958A - Permanent magnet type dc rotary electric machine - Google Patents

Abstract

PURPOSE:To increase the damagnetization bearing capacity of permanent magnets against armature reaction at the time of a high temperature by properly arranging a plurality of rare earth magnets having different temperature coefficients of coercivity in the demagnetizing field of armature reaction. CONSTITUTION:Permanent magnets 21, 22 and an auxiliary pole 3 having permeability higher than the reversible permeability of the permanent magnets 21, 22 are juxtaposed and fixed in the circumferential direction to a yoke 1 and changed into one magnetic pole, and faced oppositely to an armature 4. The temperature coefficient of coercive force at the time of a high temperature of the permanent magnet 21 on the side receiving the damagnetizing action of magnetic flux by armature reaction is made smaller than that of the coercive force of the permanent magnet 22 on another side. A rare earth magnet such as a Sm-Co group one is used as the permanent magnet 21 and a magnet such as a Nd-Fe-B group one as the permanent magnet 22.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a DC rotating electric machine using permanent magnets, and particularly to a field of DC rotating electric machines suitable as a starter for private ljj cars.
This relates to 11 magnetic poles.

[Background of the invention]

Conventionally, as this type of DC machine, for example, Japanese Patent Application Laid-Open No. 57-59
As stated in Japanese Patent No. 464, the circumferential end of a permanent magnet is subjected to maximum demagnetization work due to armature reaction.

A magnet with a large coercive force is placed in the area, a magnetic name with a large residual magnetic flux density is placed in the central part, which is subject to weak demagnetizing and weak magnetizing effects, and a circumferential end of the magnetic pole is subject to the magnetizing effect due to armature reaction. The sub-region has a magnetic pole structure using auxiliary poles. However, when high-performance rare earth magnets such as Nd-Fe-B (neodymium-iron-boron) magnets are used, the problem arises that the magnet becomes permanently demagnetized due to demagnetization at high temperatures. No consideration was given.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned prior art,
Particularly, the object of the present invention is to provide a permanent magnet type DC rotating electrical machine that uses high-performance rare earth magnets for the field and is designed to improve the permanent demagnetization resistance at high temperatures due to armature reaction.

[Summary of the invention]

The present invention was made by paying attention to the fact that when a DC rotating electric machine is downsized using high-performance rare earth magnets, the field magnet becomes hot.

In other words, in the field magnetic pole using high-performance rare earth magnets, multiple magnets are arranged in combination, and the magnet with the smallest temperature coefficient of coercive force is placed on the demagnetizing field side of the armature reaction to achieve permanent demagnetization at high temperatures. It measures the improvement of durability.

Specifically, an S m -G o (samarium-cobalt) magnet (coercivity temperature coefficient of about 0.1%/°C) is placed on the demagnetizing field side, and an Nd-Fe-B magnet (coercivity temperature coefficient of about 0.0%/°C) is placed on the demagnetizing field side. 5%
℃) is placed in close contact with the magnet to improve the permanent demagnetization resistance at high temperatures.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2. The yoke 1 includes permanent magnets 21 and 22 and an auxiliary magnet having a higher magnetic permeability than the reversible magnetic permeability of the permanent magnets. The poles 3 are fixed at 4f in the circumferential direction to form 16Ji poles, and are opposed to the armature 4. Therefore, when a current is applied to the windings of the armature 4 in the direction shown, the armature 4 rotates in the direction of the arrow. Armature reaction by the armature during load acts on the magnetic poles 21, 22.3, but if the neutral point is set to 0, there is a demagnetizing effect in the rotating direction area θ, and an increasing effect in the counter-rotating direction area 02. Both the demagnetizing effect and the magnetizing effect act more strongly toward the ends of the magnetic pole.

Therefore, in the present invention, for the purpose of downsizing the DC machine, we developed Nd-Fe magnets, which have energy several times higher than conventional ferrite magnets.
-B (neodymium-iron-boron) based rare earth magnets are used, but the drawback of this magnet is that the cue point is about 1/2 of that of Sm-Co (samarium-cobalt) based rare earth magnets.
Since the angle is around 50°, the coercive force decreases significantly at high temperatures (temperature coercivity approximately 0.5%/'C), and permanent demagnetization occurs when a large demagnetizing field acts at high temperatures. In particular, when high-performance rare earth magnets are used for the field, it is possible to downsize the rotating electrical machine, especially on the field stator side, but on the other hand, the field magnet becomes hot due to armature current, etc. .

On the other hand, S m -Co rare earth magnets are one Curie point higher and have a smaller temperature coefficient (temperature coefficient of about 0.1%/'C).
), stable magnetic properties can be obtained up to high temperatures, but the rare earth ore contains only a fraction of the amount of Sm contained in the rare earth ore, making it an expensive magnet.

Therefore, the present invention uses an S m -G o based rare earth stone 21 whose magnetic properties are stable at high temperatures in the main part on the demagnetizing field side.

By arranging an inexpensive and high-performance Nd-Fe-B magnet 22 in the remaining portion, it has become possible to prevent permanent demagnetization at high temperatures.

This dividing point is determined by selecting the most efficient point based on the performance of the permanent magnet.

〔Effect of the invention〕

As detailed above, a magnet with a small coercive force temperature coefficient is placed in the demagnetizing area due to armature reaction, an auxiliary pole is placed in a part of the magnetizing area, and a magnet with a coercive force temperature coefficient larger than that of the magnet is placed in the middle. The magnetic pole structure was combined using magnets, and the size was reduced so that I2 could be manufactured at low cost.

As a result, the high-temperature permanent yield strength was improved by 40 to 60°C compared to the case of Nd-Fe-B magnets, and a design capable of withstanding temperatures of about 200°C became possible.

[Brief explanation of drawings]

FIG. 1 is a front view of essential parts of a DC rotating electric machine according to the present invention, and FIG. 2 is a magnet characteristic curve of the DC rotating electric machine shown in FIG. 1...Yoke, 21...Sm-Go permanent magnet, 22...
・Nd-Fe-B permanent magnet, 3... Auxiliary pole, 4...
Armature.

Claims (1)

[Claims] 1. A DC rotating electric machine comprising a rotor and a stator that generates a field around the rotor, wherein the field magnetic poles of the stator divide a permanent magnet into at least two halves. In a composite field pole consisting of a first permanent magnet on the side receiving the demagnetizing effect of magnetic flux due to armature reaction, and a second permanent magnet provided in contact with a side surface of the first permanent magnet. , wherein the first permanent magnet has a smaller temperature coefficient of coercive force at high temperatures than the second permanent magnet. 2. The permanent magnet type according to claim 1, wherein the first permanent magnet is a samarium-cobalt magnet, and the second permanent magnet is a neodymium-iron-boron magnet. DC rotating electric machine.