JPH0654479A - Stepping motor - Google Patents

Abstract

PURPOSE:To facilitate an assembling method and improve the accuracy of assembling components by dividing a cylindrical impregnated bearing in circumferential direction. CONSTITUTION:A completed rotor is inserted into a completed stator 13, and next halved impregnated bearings 15a and 15b are set to sandwich a shaft 16 from both sides, and those are press-fit in the holding hole 17 of the stator 13 as they are, thereby being fixed. Hereby, the assembling of a high- performance stepping motor, which has complicated shaft structure, can be performed easily, and also the accuracy of assembling components improves.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor used for a lens driving device used in a video camera, a floppy disk head driving device, and various OA equipment driving devices.

[0002]

2. Description of the Related Art In recent years, as devices have become lighter, thinner, shorter and smaller, the stepping motors for driving them have also become smaller,
Improvement of volumetric efficiency as a motor is required.

A conventional PM type stepping motor will be described below with reference to the drawings. Figure 4 shows the conventional PM
FIG. 3 is a cross-sectional view of a mold stepping motor, in which the contact area between the shaft 1 and the cylindrical impregnated bearing 2 is reduced by reducing the outer diameter of the shaft 1 at the portion held by the impregnated bearing 2, and the loss of the bearing portion is reduced. I am letting you. The rotor is composed of a shaft 1 and a magnet 10, and the magnet 10 is fixed to the shaft 1 by press fitting and adhesion. After welding the frame 4 and the mounting plate 3, the stator of the motor fixes the impregnated bearing 2 to the mounting plate 3 by press-fitting and caulking, and then stacks the outer yoke 5, the coil 7, and the inner yoke 6 on the inside of the frame 4. After inserting and fixing the rotor, the spring 8 and the spring retainer 9 arranged at the end of the shaft 1 are fixed by caulking or welding.

[0004]

SUMMARY OF THE INVENTION Such a conventional PM
In the stepping motor, as shown in FIG. 4, the inner diameter of the cylindrical impregnated bearing 2 is equal to that of the lead screw portion 1 a of the shaft 1.
Since the outer diameter is smaller than the outer diameter of the magnet 10, it is necessary to sandwich the impregnated bearing 2 between the shaft 1 and the magnet 10 when fixing the magnet 10 to the shaft 1.
By making the shaft 1 thinner from a certain portion in this way, after fixing the shaft 1 and the magnet 10, the magnet 10 is fixed to the stator to which the cylindrical impregnated bearing 2 is fixed.
Can not be inserted. Therefore, the cylindrical impregnated bearing 2
The shaft 1 is inserted into the stator to which is fixed, and the shaft 10 is fixed inside the stator. For this reason, it becomes difficult to magnetize the screw groove position of the shaft 1 and the magnetizing position of the magnet 10 of the rotor at arbitrary positions, and when fixing the magnet 10 to the shaft 1, the impregnated bearing is used. Since care must be taken so as not to affect 2), the fixing method is limited and its accuracy is also low. In addition, the method of assembling the motor is similarly complicated.

The present invention solves the above-mentioned conventional problems, and an object thereof is to provide a stepping motor which is easy to assemble.

[0006]

In order to achieve the above object, the present invention has a structure in which a cylindrical impregnated bearing is circumferentially divided.

[0007]

According to the present invention, by mounting the bearing of the stepping motor at the end of the assembling, the assembling method is facilitated and the precision of the assembled parts is improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. 1, 2 and 3.

FIG. 1 shows a completed state of the stepping motor 4, and FIG. 2 is an enlarged view of a main part thereof. As shown in FIG. 3, the completed rotor 14 is inserted into the completed stator 13, and then the two impregnated bearings 15a and 15b are sandwiched from both sides of the shaft 16 and pressed into the holding holes 17 of the stator 13 as they are. And then fixed.

[0010]

As is apparent from the above embodiments, according to the present invention, the impregnated bearing is divided, so that a high performance stepping motor having a complicated shaft structure can be easily assembled.

[Brief description of drawings]

FIG. 1 is a perspective view of a stepping motor according to an embodiment of the present invention.

FIG. 2 is an enlarged perspective view of an essential part of the stepping motor.

FIG. 3 is an exploded perspective view of the stepping motor.

FIG. 4 is a sectional view of a conventional stepping motor.

[Explanation of symbols]

 13 Stator 14 Rotor 15a, 15b Disassembled impregnated bearing 16 Shaft

Claims (1)

[Claims] 1. A structure in which a magnet of a rotor is attached to a shaft, and an impregnated bearing for bearing the shaft is mounted in a holding hole of a mounting plate of a stator, wherein the impregnated bearing is divided in a circumferential direction. And stepping motor.