JPS6122751A - Stepping motor - Google Patents

Abstract

PURPOSE:To obtain accurate operation at minute stepping angle by alternately forming recesses and projecting strips at the prescribed pitch on the surface of a magnetic unit, and filling resin magnet in the recesses to form a rotor. CONSTITUTION:A rotor is formed by securing a cylindrical magnetic unit 15 to a rotational shaft, recesses and projecting strips 16' are alternately formed at the prescribed pitch on the peripheral surface of the unit 15, resin magnet 17 is filled in the recesses to form poles. A stator has a plurality of stator yokes having many pectinated tooth poles at the prescribed pitch and a plurality of annular stator coils 20 coupled with the stator yokes.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a stepping motor that is required to operate a printer.

[Prior Art and Problems] A conventional motor of this type will be explained with reference to FIGS. 5 and 6. FIG. 5 shows a conventional stepping motor with a permanent magnet rotor (FIG. 6). 1 is a mounting plate fixed to the device, 2 is a metal held on the mounting plate 1, 8 is a metal held on the motor bottom plate 4, and the rotary shaft 5 is rotatably supported by the metal 2.8. A cylindrical rotor magnet (permanent magnet) 6 is fixed to the rotating shaft 5 via a spacer 7 to constitute a rotor. 8a, 8b, 9a.

9b is a stator yoke group having stator magnetic pole teeth facing the rotor magnet 6 with a gap therebetween, and coil bobbin 10.11.
Together with the two-phase annular coils 12 and 18 wound around the stator. As shown in Fig. 6, the outer surface of the rotor magnet 6 is magnetized with N and S multi-poles to match the stator magnetic poles, and the step angle is determined by the number of magnetic poles. It is determined.

By the way, in the above-mentioned conventional stepping motor, in order to reduce the step angle, it is necessary to reduce the magnetization pinch of the rotor magnet, but there is a limit to the magnetization pitch, and in a general stepping motor, the minimum The maximum step angle is 7.5 degrees, and the only way to make the step angle smaller than that is to make the rotor diameter narrower. However, the popularity of stepping motors is disadvantageous from the perspective of the equipment to which they are attached and used, and large stepping motors have substantially lower step angle accuracy than small stepping motors.

The object of the present invention is to provide a stepping motor that can operate with high precision in angles.

[Structure of the Invention] The stepping motor of the present invention includes a plurality of stator yokes having a large number of parallel magnetic poles arranged at a predetermined pitch, and a plurality of stator yokes for each phase coupled to the plurality of stator yokes. A stator is constituted by a plurality of annular stator coils, and grooves and protrusions are alternately provided on the surface at a predetermined pitch so as to face the comb magnetic poles, and the grooves are filled with resin magnets. It is characterized by using a magnetic material as a rotor.

Embodiments of the present invention will be described with reference to FIGS. 1 to 4. FIG. As shown in FIG. 2, the rotor of the stepping motor of the present invention is formed by fixing a cylindrical magnetic body 15 to a rotating shaft 14, and the circumferential surface of the magnetic body 15 has a constant pitch. So it hits the concave groove 16! ! = 16' are provided alternately, and resin magnets (powder magnets molded with resin) 17 are placed in the grooves 16.
are filled to form magnetic poles. FIG. 1 shows a two-phase stator facing the rotor shown in FIG. 2. FIG. This stator is made of a magnetic material having a U-shaped cross section in the axial direction, and has a stator yoke 18a having combed magnetic poles 19a provided at a constant pitch on its inner circumferential surface, and the stator yoke 18a having alternating magnetic poles 19a. A closed magnetic path yoke 18b made of a ring-shaped magnetic material having similar comb-point magnetic poles 19b, an annular stator coil 20 wound around a bobbin 21, and the stator yoke 18
Stator yoke 2 having comb magnetic poles 28a similar to a
2a, and a sea magnetic pole 2 similar to the closed magnetic path yoke 18b.
8b, and an annular stator coil 24 wound around a bobbin 25. are respectively fitted between the stator yoke 22a and the closed magnetic circuit yoke 22b to form a stator. 26 and 27 are notches into which protective bushings 28 and 29 of the coil lead wire are fitted.

FIG. 8 shows the relative magnetic relationship between the stator and rotor. When the stator coil 20 is excited, the comb magnetic pole 19a
, 19b serve as N poles and S poles, respectively, to form a stator magnetic field. On the other hand, when the rotor is small, the field is the concave groove 16 of the magnetic body 15.
The resin magnet 17 is magnetized so that the polarity of the resin 17 filled in the resin 17 and the polarity of the protrusions 16' are different. That is, the resin magnet 17 is magnetized so that its outer surface has the same polarity (N pole).

FIG. 4 shows the configuration of the magnetic poles of the stator yoke. The angles 90° to 860° in the figure are electrical angles.

The comb magnetic poles 19a and 19b and 28a and 28b are located at 180 degrees in electrical angle. In addition, the comb magnetic pole 19b
and 28b are located at 90 degrees in electrical angle, that is, shifted by half the pitch between the magnetic poles of 19a and 19b and 28a and 28b.

[Effects of the Invention] Since the stepping motor of the present invention has the above configuration, when the stator coil 20 is excited, the magnetic poles 19a and 19b become N and S poles, respectively, and the positions corresponding to the N and 8 poles are The protrusions 16' of the rotor and the resin magnets 17 are attracted to each other. Then, when the excitation is switched from the stator coil 20 to the stator coil H, the magnetic poles 19a, 19
b is demagnetized so that the comb magnetic poles 28a and 28b are respectively N.
The rotor magnets are attracted to the positions corresponding to the north and south poles, and the rotor magnets are rotated in steps.

The rotor of the present invention is different from the conventional NS magnetized magnet rotor shown in FIG.
Since the poles can be formed by providing the protrusions 6 and 16', the precision of the stepping motor can be improved and the stepping motor can be made smaller. In addition, resin magnet 1
By performing magnetization with a magnetizing magnetic field having a saturation magnetic flux density of 7 or more, it is possible to eliminate unevenness in the magnetic field strength.

Furthermore, in order to improve rotation angle accuracy and torque characteristics, a grinding process is performed on the surface of the rotating body to make the gap between the rotor and stator constant, but at that time, ridges 16' are formed. It has excellent effects such as being able to easily remove paris.

[Brief explanation of the drawing]

1N: An exploded perspective view of the stator of the stepping motor of the present invention. Figure 2.2 A perspective view of the rotor of the stepping motor of the present invention. Figure 8.2 A relative view of the stator magnetic poles and rotor magnetic poles of the stepping motor of the present invention. Fig. 4: Developed view of stator magnetic poles of the stepping motor of the present invention Fig. 5: Cross-sectional view and perspective view of a conventional stepping motor 14...rotating shaft, 15...magnetic material, 16...concave groove, 16'...Convex strip, 17...Resin magnet, 18a...
- Stator yoke, 18b...Closed magnetic path yoke, 19a,
19b... Comb magnetic pole, 20... Stator coil,
21... Bobbin, 22a... Stator yoke, 22b
... Closed magnetic circuit yoke, 28a% 28b ... Comb magnetic pole, 24 ... Stator coil, 25 ... Bobbin, z6.
27...notch, 28.29...protective bushing 1st
Figure 2

Claims (1)

[Claims] The stator is composed of a plurality of stator yokes having a large number of comb magnetic poles arranged at a predetermined pitch, and a plurality of annular stator coils for each phase coupled to the plurality of stator yokes. , a stepping motor characterized in that the rotor is a magnetic material in which concave grooves and convex stripes are alternately provided at a predetermined pitch on the surface facing the comb magnetic poles, and the concave grooves are filled with resin magnets.