JPS6255385B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a DC machine, and particularly to a DC machine equipped with a permanent magnet field suitable for a starter or the like.

The conventional structure of this type of DC machine is to use permanent magnets with high coercive force in the demagnetizing field side area due to armature reaction, and permanent magnets with high residual magnetic flux density in the magnetizing side area, and to combine them and arrange them side by side. It constituted one magnetic pole.

However, the drawbacks of this structure are (a) permanent magnets with high coercive force and permanent magnets with high residual magnetic flux density are molded and fired separately, and a predetermined shape is created by cutting;
This was fixed in parallel to the inner circumference of the yoke to form a single magnetic pole, resulting in poor productivity. (b) Since there is a sudden change in the degree of magnetic induction at the junction of one magnetic pole, this causes noise and vibration, and furthermore, a decrease in performance due to a decrease in the amount of magnetic flux occurs.

Therefore, in order to eliminate the above-mentioned drawbacks, the present invention has a structure in which permanent magnets with different magnetic properties at one end and the other end in the circumferential direction are molded and fired, and the performance is improved by improving assembly workability and smoothing magnetic flux changes. It is ivy.

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2. 1 is a yoke, and the permanent magnet 2 is a mold in which a material with high coercive force (magnetic powder) 21 and a material with high residual magnetic flux density (magnetic powder) 22 are injected, and a mixing part 23 of both materials is provided. In this state, the end of the magnet is formed in a magnetic field so as not to impair its original characteristics, and after firing, it is cut into a predetermined shape and fixed to the yoke 1.

Next, the functions and effects of this embodiment will be explained.

In general, permanent magnets with high coercive force and high residual magnetic flux density, such as rare earth magnets, have unparalleled performance, but are expensive and are not practical for general DC machines.

Therefore, as in the present invention, a permanent magnet with a high coercive force is placed in the demagnetizing area of the armature reaction, and a permanent magnet with a high residual magnetic flux density is placed in the magnetizing area, so two permanent magnets are fixed. Productivity is superior compared to structures in which magnets are fixed. Regarding the magnetic flux waveform under load, the magnetic flux increases gradually as shown in Figure 2, but in the conventional example where different types of permanent magnets are arranged side by side, there is a sudden change in the magnet at the joint, and the amount of magnetic flux increases as shown by the dotted line. will also decrease.

As detailed above, in a permanent magnet type DC machine, the demagnetization region of the armature reaction has a high coercive force.
The magnetized region has a high residual magnetic flux density, and the joint part is made of an integrally formed and fired permanent magnet made of a mixture of these materials, and the field pole is used to increase the total magnetic flux, thereby improving performance and noise. This is a DC machine designed to prevent vibration and improve productivity.

As another example, the degree of orientation (degree of anisotropy) of the material (magnetic powder) is changed in the molding mold during magnetic field molding, and a part with high coercive force and a part with high residual magnetic flux density are formed at the ends. By making and firing,
Almost the same effect can be obtained, and in addition, when molding the material (magnetic powder) with a mold, one type of material is used, and the main parts are impregnated with additives such as barium during welding before firing to change the composition. There are various methods of manufacturing magnets, such as obtaining different magnetic properties after firing, and the same effect can be obtained by any method.

[Brief explanation of the drawing]

Fig. 1 is a front view of the main part of the DC machine according to the present invention, Fig.
The figure is an explanatory diagram of magnetic flux distribution under the same load. 1...Yoke, 2...Permanent magnet.

Claims (1)

[Claims] 1 A first magnet with high coercive force and low magnetic flux density,
In a DC machine comprising a magnetic pole consisting of a second magnet having a lower coercive force but a higher magnetic flux density than the magnet, the joint portion of the magnetic pole is made of a mixed member of the first magnet and the second magnet. A permanent magnet DC machine featuring: