JPH0145258Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stepping motor used in a magnetic disk drive device, a printer, etc., and particularly relates to the structure of a rotor and a stator of a permanent magnet type stepping motor.

In recent years, with the increasing packaging density and miniaturization of electronic devices, there has been a demand for stepping motors that are small, thin, and capable of rotating with high torque.

1 to 3 are diagrams for explaining a conventional permanent magnet type stepping motor. This type of motor has a structure in which a rotor 2 made of a cylindrical permanent magnet having a rotating shaft 1 is housed in a hollow portion of a stator 4 having a substantially cylindrical shape.
A magnetic pole portion 3 is provided on the circumferential surface of the rotor 2, in which a large number of N poles and S poles are alternately magnetized with a predetermined width.
The axial length of the magnetic pole portion 3 is designed to face stator teeth 5a, 6a, 7a, and 8a, which will be described later. The stator 4 includes four stator plates 5, 6, arranged at predetermined intervals along the axial direction.
7, 8, and a coil 9 wound around their outer peripheries.
It mainly consists of 10.

All of the stator plates 5 to 8 have the same shape, and the shape of the stator plate 5 will be explained with reference to FIG. 3 by taking the stator plate 5 as an example. The stator plate 5 is made of yoke material and has an annular shape as a whole. On its inner edge,
By bending, the plurality of stator teeth 5a are arranged at equal intervals,
Moreover, it is provided to protrude in the axial direction.

As shown in FIG. 2, the stator plates 5 and 6 are paired so as to face each other so that their respective stator teeth 5a and 6a do not come into contact with each other. Similarly, the stator teeth 7a and 8a are paired so as to face each other so as not to come into contact with each other. The stator plates 5 to 8 combined in this manner are stacked in the axial direction with spacers 11 in between. For example, if the pitch between one stator tooth 5a and the adjacent stator tooth 5a is 1 pitch, and one stator tooth 5a is used as a reference, stator tooth 8a, stator tooth 7a, stator tooth 6a are arranged so as to be shifted by 1/4 pitch in the circumferential direction.

The windings 9 and 10 are configured to excite the stator teeth 5a and 7a to the same magnetic pole, and to excite the stator teeth 6a and 8a to the same magnetic pole and opposite magnetic poles from the stator teeth 5a and 7a. When a pulse current is passed through the coils 9 and 10 in a predetermined manner according to the correspondence state between the rotor 2 and each stator tooth 5a to 8a, the magnetic pole portion 3 of the rotor 2 and the excited stator teeth 5a to 8a are connected to each other. The rotor 2 rotates in a desired direction due to magnetic repulsion and attraction.

By the way, when increasing the torque of this motor, it is necessary to increase the opposing area between the magnetic pole portion 3 of the rotor 2 and the stator teeth 5a to 8a. Therefore, the outer diameter and axial length of the motor become large, resulting in an increase in size. On the other hand, if there is a limit to the outer diameter of the motor, the stator teeth 5a to 8a cannot be made sufficiently wide in order to prevent the stator teeth 5a to 8a from coming into contact with each other, and as a result, the magnetic poles of the rotor 2 The area facing the portion 3 becomes smaller, making it impossible to obtain high torque.
Furthermore, as mentioned above, since the stator teeth 5a to 8a are formed by bending, the stator teeth 5a to 8a are not vertical due to spring back, etc., and therefore the gaps with the rotor 2 are uneven. Become,
Motor characteristics tend to become unstable.

The purpose of the present invention is to eliminate the drawbacks of the above-mentioned prior art,
To provide a permanent magnet type stepping motor that is small and thin and capable of high torque rotation.

In order to achieve this purpose, the present invention arranges at least two yoke plates along the axial direction, each having a plurality of tongue-shaped magnetic pole teeth extending horizontally inward from the inner peripheral edge of the annular portion, A rotor having a disk made of a permanent magnet with north and south poles alternately magnetized along the circumferential direction, and a coil for exciting the yoke plate to a desired magnetic pole are arranged between the yoke plates. It is characterized by

An embodiment of the permanent magnet type stepping motor of the present invention will be described below with reference to FIGS. 4 and 7. This stepping motor is composed of a rotor 12 and a stator 13, as shown in FIGS. 4 and 5. As shown in FIGS. 5 and 6, the rotor 12 has a rotating shaft 14 and a rotating shaft 1.
It is composed of two discs 15, 16 made of permanent magnets supported by a magnet 4 and arranged vertically, and spacers 17, 17 interposed between the discs. Each of the disks 15 and 16 is magnetized alternately with north and south poles along the circumferential direction to form a magnetic pole portion. In this way, the rotor 12 is installed in the case 20 via the bearing 18 and the wave washer 19.

As shown in FIGS. 4 and 5, the stator teeth 13 include stator plates 21, 22, 23, 24 made of yoke material and having an annular overall shape, and coils 25, 2.
It consists of 6. As shown in FIGS. 4 and 7, the stator plates 21 to 24 all have the same shape, and the shape will be explained below using the stator plate 21 as an example. A tongue-shaped magnetic pole tooth 21 extends horizontally inward from the inner peripheral edge of the annular portion of the stator plate 21.
A plurality of a are provided. In addition, those magnetic pole teeth 2
1a are provided at equal intervals with a width corresponding to the north pole or south pole of the rotor 12.

As shown in FIG. 5, the stator plates 21 and 22 are spaced slightly apart from the disc 15, and the stator teeth 21a and 2
2a are arranged so as to face each other in the axial direction, and are fixed in the case 20 with the rotating shaft 14 as the center. A coil 25 is wound annularly around the rotating shaft 14 in a gap surrounded by the annular portions of the stator plates 21 and 22. Similarly, the stator plates 23 and 24 are spaced slightly apart from the disc 26,
The stator teeth 23a and 24a are arranged to face each other in the axial direction, and are fixed in the case 20 with the rotating shaft 14 as the center. Stator plate 2
The coil 2 is placed in the gap surrounded by the annular parts 3 and 24.
6 is wound in an annular shape around the rotating shaft 14. Further, for example, when the pitch between one stator tooth 21a and the adjacent fixed tooth 21a is 1 pitch, and the stator teeth 21a and 22a are used as a reference,
The stator teeth 23a and 24a are both arranged so as to be offset by 1/4 pitch in the circumferential direction.

When a pulse current is passed through the coils 25 and 26 in a predetermined manner according to the correspondence state between the rotor 12 and each of the stator teeth 21a to 24a, the discs 15 and 16 of the rotor 12
The rotor 12 rotates in a desired direction due to magnetic repulsion and attraction between the magnetic pole portions and the excited stator teeth 21a to 24a.

As mentioned above, the rotor consists of a disk made of permanent magnets with N and S poles alternately magnetized along the circumferential direction, and the stator teeth of the stator are bent. This eliminates the deterioration of motor characteristics due to variations in the machining of stator teeth, making it easier to make the motor smaller and thinner. Furthermore, since the opposing area between the rotor's magnetic poles and the stator teeth can be increased, it is now possible to easily achieve high torque even when the rotor is small and thin.

[Brief explanation of the drawing]

Figures 1 to 3 relate to a conventional permanent magnet stepping motor, with Figure 1 being a perspective view showing a rotor, Figure 2 being a perspective view showing a stator, and Figure 3 being a perspective view showing a stator.
FIG. 4 is a perspective view showing a stator plate used in the stator shown in FIG. A perspective view showing the state in which the
6 is a perspective view of the rotor, and FIG. 7 is a partially sectional perspective view of FIG. 4 showing the stator plate. 14... Rotating shaft, 15, 16... Disk, 21,
22, 23, 24... Stator plate, 25, 26...
coil.

Claims (1)

[Scope of utility model registration request] At least two yoke plates having a plurality of tongue-shaped magnetic pole teeth extending horizontally inward from the inner peripheral edge of the annular portion are arranged along the axial direction, and between the yoke plates, N is arranged along the circumferential direction. 1. A permanent magnet type stepping motor comprising: a rotor having a disk made of a permanent magnet with alternately magnetized poles and south poles; and a coil for exciting the yoke plate to a desired magnetic pole.