JPS59204454A - Rotor for motor - Google Patents

Abstract

PURPOSE:To prevent a rotor cylinder and the center of a rotational shaft from displacing, to prevent the cylinder from cracking and to simplify the structure and the manufacture of a motor by interposing thermoplastic resin mixed with ultrafine amount of inorganic component between the cylinder and the shaft. CONSTITUTION:A motor rotor has a rotor cylinder 1, a rotational shaft 2, and a plastic material 3. The cylinder 1 is formed of ferrite magnet, and multipolarized at the outer periphery. The material 3 couples the cylinder 1 and the shaft 2, and is interposed therebetween. The material 3 contains small amount of inorganic component in thermoplastic resin, and provided by molding in a mold. The resin contains phenol resin, polybutylene terephthalate, polyacetal, etc. and the inorganic component contains glass beads, flake glass, glass short fiber, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a rotor that is used in electric motors such as stepping motors and micromotors, and includes a rotor cylinder made of ferrite magnets whose outer peripheral surface is magnetized.

[Technical Background of the Invention and its Problems J] A rotor with a large diameter rotor cylinder is provided with a bushing via an adhesive layer on the inner peripheral surface of the rotor cylinder with inner diameter accuracy.
This bushing is formed by press-fitting a fitting member into which a rotating shaft is fixedly fixed through the bushing.

However, this rotor structure not only requires a great deal of effort to assemble and process the inner peripheral surface of the rotor cylinder, but also requires a large torque at startup due to the weight of the bushing. There is a drawback that the center of the rotating shaft and the center of the rotor cylinder body are misaligned due to the tolerance between the outer diameters of the rotor and the adhesive layer.

Further, a rotor having a small diameter rotor cylinder is formed by molding a plastic material between the rotor cylinder and a rotating shaft provided through the center of the cylinder. The plastic material was formed only from a resin component such as polyacetal.

However, this rotor structure tends to cause contraction in the radial and axial directions of the rotor when the plastic material hardens.

The shrinkage of this plastic material is more pronounced as the amount of plastic material increases, in other words, the larger the diameter of the rotor cylinder, and especially when a rotor cylinder whose inner peripheral surface is not dimensioned is used, the shrinkage of the plastic material becomes more pronounced. Unbalanced contraction occurs in the direction. Therefore, due to such contraction, there is a problem that the center of the rotary shaft and the center of the rotor cylindrical body are considerably shifted, and the rotor cylindrical body is easily cracked.

[Purpose of the invention]

Therefore, an object of the present invention is to be able to prevent the center of the rotor cylinder from being misaligned with the rotating shaft regardless of the diameter of the rotor cylinder, prevent cracks in the rotor cylinder, and further improve the structure and manufacturing. Our objective is to provide a simple and high-quality rotor for electric motors.

[Summary of the invention]

That is, the rotor for an electric motor according to the present invention has a plastic material interposed between the rotor cylinder body and a rotating shaft provided axially passing through the center of the rotor body, and a fine inorganic material. It is characterized by being made of thermoplastic resin mixed with ingredients.

According to a rotor for an electric motor having this feature, since the rotor for an electric motor is composed only of a rotor cylindrical body, one rotating shaft, and a plastic material, the bushing, adhesive layer, and fitting required for conventional large rotors are The mating member can be omitted. Therefore, the structure is extremely simple, and since it can be manufactured by simply molding a plastic material using a mold, it can be easily manufactured without the need for complicated assembly or processing as in the past, and can be constructed at low cost. Since the plastic material has a structure in which a small amount of inorganic component is mixed, the shrinkage rate of the entire plastic material can be minimized due to the inorganic component evenly distributed throughout the plastic material. Such shrinkage prevention prevents misalignment of the center between the rotor cylinder and the rotating shaft regardless of the diameter of the rotor cylinder, and also prevents cracking of the rotor cylinder after shrinkage of the plastic material. Furthermore, physical properties such as heat resistance, chemical resistance, and mechanical strength of the plastic are improved by the minute inorganic components. Therefore, for these reasons, it is possible to provide a rotor for an electric motor that is constructed with high quality.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

The rotor for an electric motor includes a rotor cylinder 1, a rotating shaft 2, and a plastic material 3. The rotor cylindrical body 1 is made of ferrite magnet, and at least its outer diameter is precisely machined, and its outer circumferential surface is multipolarly magnetized. The cylindrical body 1 is a large one having an outer diameter of, for example, about 30 mm. The rotating shaft 2 is made of metal and is provided so as to pass through the center of the rotor cylinder body 1 in the axial direction. Further, the plastic material 3 is provided to connect the rotor cylinder body 1 and the rotating shaft 2 and to be interposed between them. This plastic material 3 is made of thermoplastic resin mixed with a minute inorganic component, and is provided by molding using a mold. Thermoplastic resin components include phenolic resin and poly!
Tylene terephthalate, polyacetal, etc. can be used, and as the inorganic component, glass beads, flaky glass, glass 5-short fibers, etc. can be used. In addition, this example shows the case where a plastic material 3 made of polybutylene terephthalate mixed with flaky glass is used, and the mixing ratio of the inorganic component affects the fluidity of the plastic material 3 during molding. For guarantee purposes, the amount is set at around 50 cents, for example. The plastic material 3 also includes a flange portion 4 that is in close contact with the end surface of the rotor cylinder body 1, a cylinder body contact portion 5 that is in close contact with the inner peripheral surface of the rotor cylinder body 1, a shaft contact portion 6 that is in close contact with the rotating shaft 2, and a cylinder body contact portion 5 that is in close contact with the inner peripheral surface of the rotor cylinder body 1. It is formed with a rib portion 7 that connects the body contact portion 5 and the shaft contact portion 6.

Although the above-mentioned embodiment is constructed as described above, the specific structure of the rotor cylindrical body 1 rotation axis, the plastic material, the inorganic component of the plastic material, the resin component, etc. , shape, position, material, etc., can of course be implemented in various configurations as long as they do not go against the gist of the present invention.

〔Effect of the invention〕

The gist of the present invention described above is the structure described in the claims above. Therefore, according to the present invention, the number of parts is small, the structure is simple, and it can be easily manufactured without requiring assembly. In addition, minute inorganic components can improve the physical characteristics of mixed plastics, and this can cause cracks in the rotor cylinder and misalignment of the center between the rotor cylinder and the rotation axis. Since shrinkage of objects can be prevented, quality can be improved.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, with the first figure being a perspective view and the second figure being a perspective view.
The figure is a side view, and FIG. 3 is a sectional view taken along the line m--■ in FIG. 2. 1... Rotor cylindrical body, 2... Rotating shaft, 3... Plastic material. Applicant's agent Patent attorney Takehiko Suzue 7- Figure 1 Figure 2 2■ Figure 3 2

Claims (1)

[Claims] A rotor cylinder made of ferrite magnets whose outer circumferential surface is magnetized with multiple poles, a rotating shaft that passes through the center of the rotor cylinder in the axial direction, and a thermoplastic resin mixed with a minute inorganic component. A rotor for an electric motor, comprising a plastic material interposed between the rotor cylindrical body and a rotating shaft.