JPS6160665B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in a small electric motor and its manufacturing method.

Conventionally, stator assemblies of small electric motors have been constructed using magnetic pole cores with excitation windings on the inner surface of a cylindrical yoke made of steel plate that also serves as the motor case, or permanent magnets made of magnetic steel or fired ferrite magnets. It is often used to configure the device by attaching it to the device.

However, in the case of the stator assembly having the above configuration, each part of the yoke and the magnetic pole iron core is made and assembled separately, so errors are likely to occur in the accuracy of each part and the assembly, and the point of the motor output is The air gap between the stator (magnetic pole iron core) and rotor cannot be made smaller than a certain limit. In particular, wire-wound iron cores require a large number of parts and materials, resulting in high costs. In addition, the production of ferrite magnets used for exciting iron cores involves time-consuming processes such as secondary firing and polishing.
In addition, there is a reduction in material yield due to polishing treatment and energy loss during firing treatment.

This invention was made to solve all of the above problems, and it is necessary to pay special consideration to the accuracy of each part of the motor case, yoke, and magnetic pole core that make up the stator assembly of the motor. The main object of this invention is to provide a small-sized electric motor and a method for manufacturing the same, which has almost no assembly errors and can reduce the gap between the magnetic pole iron core and the rotor.

In the electric motor according to the present invention, a cylindrical body portion having an opening penetrating through diametrically opposed portions and a rotor bearing bracket portion provided at one of the cylindrical mouths are integrally molded from a synthetic resin material or an equivalent material. an electric motor case, a cylindrical yoke held concentrically on the inner circumferential side of the cylindrical body portion and having an opening communicating with the opening of the cylindrical body portion, and the opening of the cylindrical body portion and the cylindrical yoke. Ferrite for stators is made by mixing ferrite powder into a synthetic resin material or an equivalent material that is injected concentrically into the inside of the cylindrical body through the opening of the yoke and magnetically coupled with the cylindrical yoke. It is characterized by being made of a magnetic material.

Furthermore, the method for manufacturing the electric motor having the above configuration includes integrally molding the cylindrical part that becomes the motor case and the rotor bearing bracket part positioned at one of the cylindrical openings from a synthetic resin material by using ordinary synthetic resin molding means. During the forming process, a cylindrical yoke having a communication opening for the molding material at diametrically opposed parts is held concentrically in the cylindrical body part, and the cylindrical yoke is held concentrically in the cylindrical body part. Openings are formed to expose the yoke part including the material communication openings on both the inside and outside sides thereof, and then the cylindrical yoke is molded into the opening of the cylindrical body part by ordinary synthetic resin molding means. By injecting a synthetic resin material containing ferrite powder into both the inner and outer parts of the material communication opening, a ferrite resin magnetic pole body that holds the cylindrical yoke between the inner and outer parts and is concentric with the cylindrical part is formed. It is characterized by subjecting the magnetic pole body to a magnetization process.

Hereinafter, the present invention will be explained in detail based on the drawings showing an example of its implementation.

In Figures 1 to 5, numeral 1 indicates a cylindrical body part serving as a motor case, 2 and 3 designate bracket parts for rotor bearings, and the cylindrical body part 1 and one bracket part 2 are made of ordinary resin molding. The other bracket part 3 is integrally molded by means and is attached to the cylindrical body part 1 with screws.

A cylindrical yoke 5 having communication openings 4 at diametrically opposed portions is recessed inside the cylindrical body portion 1 . Further, the cylindrical body portion 1 is provided with an opening 6 for exposing the yoke portion including the communication opening 4 of the cylindrical yoke 5 on both the inside and outside sides thereof. A magnetic pole body 7 made of synthetic resin containing ferrite powder is formed concentrically with the cylindrical body part 1 on the inner part of the yoke and the outer part of the opening 6, and is magnetized by an appropriate means. ing. 8 is a rotor, 9 is a shaft, 10 is a commutator, and 11 is a brush.

According to the electric motor stator assembly constructed as described above, the following excellent effects can be obtained.

(1) The cylindrical part that becomes the motor case and the bracket part positioned at one of the cylindrical openings of the cylindrical part are integrally molded from a synthetic resin material, and a part of the cylindrical body has a magnetic pole body made of a ferrite resin material. Since they are integrally molded, the concentric precision between the cylinder body and the bearing bracket, as well as the concentric precision between the magnetic pole body and the bearing bracket, can be greatly improved. can be reduced to a minimum.

(2) Since the ferrite magnetic pole body is a molded body of resin material containing ferrite powder, there is no need for secondary firing and shaping unlike conventional ferrite magnets, and there is no thermal distortion during firing, so it is easy to remove distortion. Polishing is no longer necessary, which helps improve material yield and energy savings.

(3) The assembly work of the electric motor can be greatly simplified and manufacturing costs can be reduced.

Next, a method of manufacturing the electric motor fixing assembly having the above structure will be described.

6 to 9 show an example of the manufacturing method.

First, using a resin molding machine and a mold (not shown), as shown in FIG. are integrally molded concentrically from a synthetic resin material, and at the time of molding, an opening 6 is formed in the cylindrical body part 1. Next, some of the nests (not shown) are replaced in the same mold, and as shown in FIG. 7, synthetic resin material containing ferrite powder is injected from both sides of the cylindrical yoke 5, A magnetic pole body 7 extending from the inside and outside of the iron 5 through the communication opening 4 is formed concentrically with the cylindrical body part 1. Thereafter, the magnetic pole body 7 is magnetized by an excitation machine (not shown) to form a ferrite magnet body.

Another preferred method for magnetizing the magnetic pole body 7 is described in the eighth section.
9 and 9. That is, 10 is an iron core of an excitation machine, 11 is an excitation coil, and a synthetic resin injection gate 12 is formed at a predetermined portion of the iron core 10, and the synthetic resin material containing ferrite powder is injected through the gate 12. At the same time, a weak magnetic field is applied to the resin material in a fluid state to make the ferrite anisotropic, and after the resin material has hardened, a strong magnetic field is applied to magnetize it, resulting in a magnetic pole body with high performance.

As described above, according to the present invention, there is no need to pay special consideration to the accuracy of each component of the motor, such as the motor case, yoke, and magnetic pole body, and there is almost no assembly error. An electric motor is obtained in which the air gap between the magnetic pole body and the rotor can be reduced.

Further, according to the present invention, not only can the electric motor having the above-mentioned configuration be manufactured very simply and easily using conventional resin molding machines and molds, but also the anisotropic treatment and magnetization treatment of ferrite can be performed in the manufacturing process. Therefore, it is possible to improve productivity and reduce manufacturing costs.

[Brief explanation of the drawing]

Fig. 1 is a front view of a small electric motor showing an embodiment of the present invention, Fig. 2 is a vertical sectional view, Fig. 3 is a plan view of the motor case, and Fig. 4 is a cross section taken along line X-X in Fig. 2. Figure 5 is a perspective view of the cylindrical yoke, Figures 6 and 7 are longitudinal sectional views of the main parts of the motor showing the manufacturing process, and Figure 8 is the main part of the motor with the magnetizing machine connected in series. The vertical sectional view and FIG. 9 are plan views. 1... Cylinder part, 2, 3... Bracket part, 4...
...Communication opening, 5...Cylindrical yoke, 6...Opening, 7
...Magnetic pole body, 8...Rotor, 9...Shaft, 10...
Commutator, 11...brush.

Claims (1)

[Scope of Claims] 1. A cylindrical body portion having openings penetrating through diametrically opposed portions and a rotor bearing bracket portion provided at one of the cylindrical mouths are integrally molded from a synthetic resin material or an equivalent material. a cylindrical yoke held concentrically on the inner peripheral side of the cylindrical body and having an opening communicating with the opening of the cylindrical body; and an opening of the cylindrical body and the cylindrical yoke. A stator made of a synthetic resin material or a similar material mixed with ferrite powder, which is injection molded so as to protrude concentrically into the inside of the cylindrical body through an opening in the iron, and is magnetically coupled to the cylindrical yoke. An electric motor characterized by being made of a ferrite magnetic material. 2.During the molding process of integrally molding the cylindrical part that will become the motor case and the rotor bearing bracket part located at one of the cylindrical openings from a synthetic resin material using ordinary synthetic resin molding means, the parts that face each other in the diametrical direction are A cylindrical yoke having a forming material communication opening at a portion thereof is held concentrically in the cylindrical body part, and a yoke part including the material communication opening of the yoke is held in the cylindrical body part. Openings for exposure are formed on both the inner and outer sides of the cylindrical body, and then a synthetic resin material containing ferrite powder is injected into both the inner and outer parts of the cylindrical body through the cylindrical body using ordinary synthetic resin molding means. A method of manufacturing an electric motor, which comprises forming a ferrite resin magnetic pole body that holds a yoke between its inner and outer parts and is concentric with a cylindrical body part, and magnetizing the magnetic pole body. 3. During the molding process of integrally molding the cylindrical body part that will become the motor case and the rotor bearing bracket part positioned at one of the cylindrical openings from a synthetic resin material using ordinary synthetic resin molding means, the cylindrical body part that will become the motor case and the bracket part for the rotor bearing located at one of the cylindrical mouths are integrally molded from a synthetic resin material. A cylindrical yoke having a forming material communication opening at a portion thereof is held concentrically in the cylindrical body part, and a yoke part including the material communication opening of the yoke is held in the cylindrical body part. Openings for exposure are formed on both the inner and outer sides of the cylindrical yoke, and then, at the opening of the cylindrical body part, the material is passed through the material communication opening of the cylindrical yoke to the inner and outer parts of the cylindrical yoke. By injecting a synthetic resin material containing ferrite powder, a ferrite resin magnetic pole body is molded that holds the cylindrical yoke on both its inner and outer sides and is concentric with the cylindrical body. A method for manufacturing an electric motor, characterized by subjecting it to anisotropic treatment, and then subjecting it to magnetization treatment after hardening.