JPH06178525A - Stator yoke for stepping method - Google Patents

Abstract

PURPOSE:To prevent the damping of a rotor without the deterioration of the accuracy of a step angle by forming the shape of a magnetic pole tooth as the stepped shape, wherein rectangular teeth are overlapped, or as the curved shape for the tip of the magnetic pole with the rectangular tooth. CONSTITUTION:A plurality of magnetic pole teeth 13 are provided at the center of a stator yoke B 3. In the magnetic pole tooth 13, the lengths of rectangular parts 1 and 2 are made to be (c) and (d), respectively, and the width of the magnetic pole is (a). The widths (a) and (b) and the widths (c) and (d) of the stepped magnetic pole tooth 13 are determined with the inertia of a torque rotor. The vibrating force when a stepping motor is driven is suppressed, and the accuracy of the step angle is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The stator yoke of a stepping motor according to the present invention relates to a stator yoke of a stepping motor used as a power source for office automation equipment, automobiles, optical equipment and the like.

[0002]

2. Description of the Related Art It has been known that a stator yoke of a stepping motor has a rectangular magnetic pole tooth shape as disclosed in, for example, Japanese Patent Laid-Open No. 56-86054. As another technique, as disclosed in Japanese Patent Publication No. 322747/1989, a method for manufacturing a tapered magnetic pole tooth has been known. Although the manufacturing method is used in any of the examples, the magnetic pole teeth of the obtained stator yoke are rectangular or tapered.

[0003]

(1) When the magnetic pole teeth are rectangular, the stepping angle accuracy of the stepping motor when incorporated in the stepping motor is high, but when the rotor is started or stopped. There was a problem that vibration (damping) increased.

(2) When the magnetic pole teeth are tapered, the damping of the rotor of the stepping motor when it is incorporated into the stepping motor is small, but the step angle accuracy of the rotor is low although the damping is small. There was a problem.

This is because the cylindrical magnet of the rotor is magnetized in a strip shape on the surface of the cylindrical magnet, but the problem is solved without improving the magnetization of the cylindrical magnet. It was desired to do.

Therefore, an object of the present invention is to provide a stator yoke of a stepping motor which can prevent the damping of the rotor when the motor is driven without degrading the step angle accuracy of the stepping motor.

[0007]

In the present invention, in order to solve the above-mentioned problems, (1) the shape of the magnetic pole teeth is a stepped shape in which rectangular teeth are superposed (2) the shape of the magnetic pole teeth The present invention provides a stator yoke of a stepping motor, which has a rectangular tooth and a magnetic pole tip having a curved shape.

[0008]

1 is a semi-longitudinal sectional view of a stepping motor to which a stator yoke of a stepping motor according to first to third embodiments of the present invention is applied.

In the stepping motor 1, a stator yoke A2 and a stator yoke B3 forming a magnetic circuit are electrically excited from the outside by a coil 5 wound around a coil bobbin 4 made of an insulating material, so that the stator yoke A2 and the stator. The mounting plate 6 and the bearing 8 of the cover 7, which are respectively mounted on the yoke B3, rotatably support the shaft 10 of the rotor 9, and the yoke 11 fixed to the shaft 10 is magnetized into a strip shape. Is provided with a cylindrical magnet having a stator yoke A2 and a stator yoke B.
3 is opposed to 3 with a small air gap.

FIG. 2 is a sectional view of a stator yoke of a stepping motor showing a first embodiment of the present invention.

The plurality of magnetic pole teeth 13 provided in the central portion of the stator yoke B3 are constituted by a rectangular portion a having a width a of the magnetic pole tooth and a rectangular portion b having a width b. The lengths are c and d, respectively. Here, the widths a and B, and the widths c and d of the stepped magnetic pole teeth 13 have appropriate values in order to improve the step angle accuracy and damping which are the objects of the present invention. The appropriate value is determined by the magnetomotive force of the coil that excites the motor, the shape and material of the cylindrical magnet 12 of the rotor 9, the air gap, the torque generated by the stepping motor 1, and the inertia of the rotor 9. .

However, according to the experiments conducted by the present inventor, a better result is obtained when the width a is larger than the width b.
The number of the rectangular portions forming the step of the stepped magnetic pole tooth 13 was three, more preferably four, and the good result was obtained.

FIG. 3 is a sectional view of a stator yoke of a stepping motor showing a second embodiment of the present invention.

The plurality of magnetic pole teeth 14 provided at the central portion of the stator yoke B3 are provided with a rectangular portion c having a width f of magnetic pole teeth and a length f, and a curve having a radius R at the tip of the rectangular portion c. The shape parts D are arranged in series. Here, it goes without saying that the length f and width e of the rectangular portion c and the dimensions of the curved portion d are appropriate values peculiar to the stepping motor as in the first embodiment.

FIG. 4 is a sectional view of a stator yoke of a stepping motor showing a third embodiment of the present invention.

The plurality of magnetic pole teeth 15 provided in the central portion of the stator yoke B3 are provided with a rectangular portion h having a width h of the magnetic pole teeth and a length h. The rectangular portion e has a small radius at its tip. The trapezoidal portion provided with r is continuously formed. Here, the dimensions of the length h and width g of the rectangular portion e and the small radius r of the trapezoidal portion are
It goes without saying that an appropriate value specific to the stepping motor is good as in the first and second embodiments.

In the above implementation, the magnetic pole teeth 13, 14, ...
Although reference numeral 15 has been described with a planar shape in which each magnetic pole tooth is expanded, in reality, since it faces the cylindrical magnet 12 of the rotor 9 via a minute air gap, a curved surface shape having a constant pole ratio is more effective. Is. Further, only the stator yoke B3 has been described, but it goes without saying that the same shape as the stator yoke B3 is preferable for each of the stator yoke A2.

[0018]

According to the present invention, since the structure shown in claim 1 and claim 2 is provided, the vibration force when the stepping motor using the stator yoke of the stepping motor of the present invention is driven is suppressed, Further, since the step angle accuracy is improved, not only vibration and noise are reduced in an OA device such as a printer, discomfort given to the user is reduced, but also the print quality is greatly improved. was gotten.

[Brief description of drawings]

FIG. 1 is a semi-longitudinal sectional view of a stepping motor to which a stator yoke of a stepping motor according to first to third embodiments of the present invention is applied.

FIG. 2 is a sectional view of a stator yoke of the stepping motor showing the first embodiment of the present invention.

FIG. 3 is a sectional view of a stator yoke of a stepping motor showing a second embodiment of the present invention.

FIG. 4 is a sectional view of a stator yoke of a stepping motor showing a third embodiment of the present invention.

[Explanation of symbols]

 1 Stepping Motor 2 Stator Yoke A 3 Stator Yoke B 4 Coil Bobbin 5 Coil 6 Mounting Plate 7 Cover 8 Bearing 9 Rotor 10 Shaft 11 Yoke 12 Cylindrical Magnet 13, 14, 15 Magnetic Pole I, R, C Curved section F Trapezoidal section

Claims (2)

[Claims] 1. A stator yoke in which a plurality of magnetic pole teeth are provided at a central portion of a magnetic circuit forming a magnetic circuit, a stator coil for performing pulse excitation on the magnetic pole teeth, and a rotor including a cylindrical magnet. In the stator yoke of the stepping motor according to the present invention, the pole tooth shape is a stepped shape in which rectangles are overlapped with each other. 2. A stator yoke for a stepping motor, wherein the magnetic pole tooth shape is a rectangular tooth, and the magnetic pole tooth tips are partially curved.