JP2000152524A - Structure of rotor-side yoke for motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure of a rotor-side yoke for a motor, requiring less initial cost and machining cost and with enhanced reliability by obviating molds and machining of plate materials and eliminating yokes which fall off due to change in temperature so that yokes can be surely secured. SOLUTION: A fan base 5 formed of plastic material and fans 5a formed on the rim of the fan base 5 are formed integrally. The fan base 5 has a spring yoke 1 which is press-fit on its inner circumference. The spring yoke 1 uses a wire material of circular cross section and is formed into a winding coil as shown in figures (c) and (d). A plastic magnet 2 is press-fit inside the spring yoke 1. As shown in figure (b), the contact face of the spring yoke 1 bites into the inner wall face of the fan base 5 and the rim of the plastic magnet 2, which matches at press-fitting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor-side yoke structure of a motor, and more particularly, to a rotor magnet magnetic yoke in, for example, a brushless motor.

[0002]

2. Description of the Related Art FIGS. 3A and 3B are views for explaining an example of a rotor structure of a conventional motor. FIG. 3A is a sectional view of a rotor portion, and FIG. 3B is a perspective view of a ring yoke. Fan 13
The ring yoke 14 is attached to the inner wall surface of the fan base 13 having the outer periphery a, and the magnet 15 is fixed inside the ring yoke 14. A shaft 16 is fixed to the center of the fan base 13.

[0003]

In the structure of the rotor 12, the ring yoke 14 has a ring shape with an L-shaped cross section, and requires a manufacturing process using a press die and a drawing die. Further, the ring yoke 14 is manufactured by processing a plate material, so that a loss occurs in the material. Furthermore, because of the drawing structure, rust prevention after processing (plating, painting)
Have to do. The ring yoke is mounted by press-fitting. In heat shock and high-temperature tests, the yoke is loosened due to temperature changes, and it is necessary to reinforce the yoke with an adhesive in order to prevent it from falling off.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, so that machining of a mold and a plate material is not required, thereby reducing initial costs and machining costs, and preventing the yoke from falling off due to a temperature change so that the yoke can be securely fixed. Accordingly, it is an object of the present invention to provide a motor rotor-side yoke structure with improved reliability.

[0005]

According to the present invention, there is provided a rotor yoke structure for a motor according to the present invention, wherein a base of the rotor is formed of a plastic material, and a magnet magnetic yoke attached to the rotor is formed of a coil spring. The coil spring is press-fitted into the plastic base of the rotor, and a plastic magnet is press-fitted inside the coil spring. Further, the plastic magnet in the present invention is constituted by a plastic magnet or a rubber magnet.

[0006]

According to the above construction, when the spring is press-fitted into the base, the press-fitting contact area is reduced, and the contact surface of the spring bites into the base, so that it is possible to prevent the spring from coming off due to thermal expansion. In addition, since a mold and a plate are not used, initial costs and processing costs can be reduced.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a view showing an embodiment of a rotor-side yoke structure of a motor according to the present invention.
(A) is a sectional view of a rotor portion, (b) is a partially enlarged sectional view near a spring yoke, (c) is a perspective view of the spring yoke, and (d) is a sectional view of the spring yoke. The fan base 5 made of platinum switch material and the fan 5a formed on the outer peripheral surface of the fan base 5 are integrally formed. The shaft 3 is fixed to the center of the fan base 5. The spring yoke 1 is pressed into the inner peripheral surface of the fan base 5. The spring yoke 1 is made of a wire having a circular cross section, and is formed in a wound coil shape as shown in FIGS.

A plastic magnet 2 is press-fitted inside the spring yoke 1. As shown in (b), the contact surface portion of the press-fitted spring yoke 1 digs into the inner wall surface of the fan base 5 and the outer peripheral surface of the plastic magnet 2. This is because the area of press-fitting the spring yoke 1 into the fan base 5 and the plastic magnet 2 when press-fitting is small, and the fan base 5 and the magnet are plastic.

When the temperature rises, the outer peripheral surface and the inner wall of the fan base 5 expand outward (the outer diameter and the inner diameter increase), and similarly, the outer peripheral surface and the inner wall of the plastic magnet 2 also expand outward. Although the distance between the inner wall of the fan base 5 and the outer peripheral surface of the plastic magnet 2 is substantially unchanged due to the thermal expansion of the fan base 5 and the plastic magnet 2, the spring yoke 1 has a smaller coefficient of thermal expansion than the fan base 5 and the plastic magnet 2. Since the spring yoke 1 expands and has a high hardness, the spring yoke 1 is harder to come off in the biting and press-fitting direction.

FIG. 2 is a sectional view of a rotor portion when the present invention is applied to an inner motor. A spring yoke 11 is pressed into the outer periphery of the base 7a of the rotor 7, and a plastic magnet 10 is pressed into the outside thereof.
The coil 9 is arranged so as to face the plastic magnet 10. Also in this embodiment, the mounting and the effect of the spring yoke 11 are the same as those of FIG. Although FIGS. 1 and 2 show an example of a plastic magnet as the plastic magnet, a rubber magnet may be used as a matter of course.

[0011]

As described above, according to the present invention, since the yoke is formed by a spring, the spring yoke is pressed into the base of the rotor, and the plastic magnet is mounted inside the spring yoke, the yoke is manufactured. No press die is required, and initial costs can be reduced. Further, since the yoke is made of a spring material instead of a plate material, material loss during processing is eliminated. In addition, since a plastic magnet is used as the magnet, the spring yoke fits into (penetrates into) the outer peripheral wall of the magnet and the inner wall of the rotor, so that the yoke and the magnet are securely fixed and reliability is improved, and the base of the rotor is improved. It is no longer necessary to apply an adhesive between the yoke and the yoke and the magnet.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of a rotor-side yoke structure of a motor according to the present invention, wherein FIG.
(B) is a partially enlarged sectional view near the spring yoke,
(C) is a perspective view of the spring yoke, and (d) is a cross-sectional view of the spring yoke.

FIG. 2 is a sectional view of a rotor portion when the present invention is applied to an inner motor.

3A and 3B are views for explaining an example of a rotor structure of a conventional motor, in which FIG. 3A is a cross-sectional view of a rotor portion, and FIG.

[Explanation of symbols]

 1,11 ... Spring yoke 2 ... Plastic magnet 3,8,16 ... Shaft 4,7,12 ... Rotor 5,13 ... Fan base 9 ... Coil 10,15 ... Plastic magnet 14 ... Ring yoke

Claims (2)

[Claims] 1. A base of a rotor is formed of a plastic material, a magnet magnetic yoke to be attached to the rotor is formed of a coil spring, and the coil spring is pressed into a base of the plastic material of the rotor to form a coil spring. A rotor-side yoke structure for a motor, wherein a plastic magnet is press-fitted inside. 2. The rotor-side yoke structure for a motor according to claim 1, wherein the plastic magnet is a plastic magnet or a rubber magnet.