JPH06296356A - Stepping motor - Google Patents

Abstract

PURPOSE:To provide a stepping motor with a small outer diameter, in which a coal is easily wired. CONSTITUTION:A stepping motor comprises a shaft 1 for mounting a magnet 2, a pair of bearings 4 provided on both sides of an axis of the magnet 2 for supporting the shaft 1', a bobbin member 8 projected opposite to the magnet 2 and fixed coaxially with each bearing 4, and a coil 10 provided around the bobbin member 8, and yoke members 12, 14, 18, and 20 made of soft magnetic material and including polar tooth parts 12A, 14A, 18A, and 20A, each fixed on both end of each bobbin member 8 and projected opposite the surrounding face of the magnet 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor, and more particularly to an improvement for reducing the motor outer diameter and facilitating wiring to a coil.

[0002]

2. Description of the Related Art For example, a three-dimensional display that represents a three-dimensional shape by arranging a plurality of small stepping motors vertically along the same plane and driving one pin up and down by these stepping motors has been studied. ing.

Stepping motors used for such applications are particularly required to have a small motor diameter so that the arrangement density can be increased, and to facilitate coil wiring even when the arrangement density is high. .

[0004]

By the way, in a stepping motor which is normally used, a structure in which a pair of coils is arranged so as to surround the outer circumference of a magnet is generally used. In this structure, the coils are large. There is a problem in that it is difficult to satisfy the above conditions because the diameter cannot be avoided.

Therefore, the present inventors have arranged a coil on both sides in the axial direction of the magnet, and provided a yoke extending from both ends of the coil to a position facing the outer circumference of the magnet to reduce the outer diameter of the motor. I had an idea.

However, in this case, when the outer circumferences of the coil and the magnet are covered with a case and the shaft is supported by bearings fixed to both ends of the case as in the conventional motor,
There is a problem in that the wiring of the coil must be drawn out by forming a hole in the end surface of the case, and when the motors are arranged at a high density, the wiring work of the coil is difficult and it is difficult to satisfy the above conditions.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a stepping motor in which the outer diameter of the motor can be reduced and the wiring of the coil is easy even when the size is reduced.

[0008]

In a stepping motor according to the present invention, a cylindrical magnet is coaxially fixed to a shaft, and the shaft is rotatably supported adjacent to both sides of the magnet in the axial direction. A pair of bearings, a cylindrical soft magnetic body bobbin member coaxially fixed to each of the bearings so as to extend to the opposite side of the magnet, and coils arranged on the outer circumference of each of the bobbin members, And a yoke member made of a soft magnetic material, which is fixed to both ends of each bobbin member and has pole teeth extended to a position facing the outer peripheral surface of the magnet.

[0009]

This stepping motor has a structure in which the coils are arranged on both sides in the axial direction of the magnet, so that the outer diameter of the coil and thus the outer diameter of the motor can be reduced. Further, since a bearing that supports the shaft is arranged between the magnet and each coil, and the bobbin member having the coil and the yoke fixed thereto is fixed to these bearings, the above-mentioned parts are housed and positioned relative to each other. Need not be provided. Therefore, the wiring of each coil can be drawn out from the gap between the pole teeth of the yoke member, the degree of freedom of wiring is high, and the wiring is easy even when the motors are arranged at a high density.

[0010]

1 is a longitudinal sectional view showing an embodiment of a stepping motor according to the present invention, and FIG. 2 is a transverse sectional view thereof. In the figure, reference numeral 1 denotes a shaft 1, and a plurality of (four poles in this example) columnar magnets 2 are fixed to the outer circumference of the shaft 1 through a pair of ring plates 6. A pair of metal bearings 4 that rotatably support the shaft 1 are arranged adjacent to each other on both sides of the magnet 2 in the axial direction.
A cylindrical bobbin member 8 made of a soft magnetic material is coaxially fixed to the magnet so as to extend to the side opposite to the magnet 2.

Coils 1 are provided on the outer circumference of the bobbin member 8, respectively.
0 is wound, and in this embodiment, the outer diameter of each coil 10 is about the outer diameter of the magnet 2. Step portions 8A and 8B are formed at both ends of the bobbin member 8, and inner yoke members 12 and 18 are provided on the step portion 8B on the magnet 2 side (inside).
The outer yoke members 14 and 20 are fixed to the outer step portion 8A. These yoke members 12, 14, 1
Both 8 and 20 are made of soft magnetic material.

The inner yoke member 12 (18) has a short U-shape, and the pair of parallel portions has pole teeth 12A (18A).
As opposed to the outer peripheral surface of the magnet 2 in the axial direction half thereof in substantially parallel to each other. Also, the outer yoke member 14 (20)
Has a long U-shape, and the pair of parallel portions has polar teeth 14
As A (20 A), the magnet 2 faces the outer peripheral surface of the half of the magnet 2 in the axial direction substantially in parallel.

The pole teeth 12A, 14A, 18A, 20A of each yoke member 12, 14, 18, 20 are pole teeth 12A and 14A fixed to the same bobbin member 8 as shown in FIG.
A, 18A, and 20A are positioned so that their phases differ by 90 ° from each other, and the pole teeth facing each other with the magnet 2 in between are positioned by 45 ° in phase. However, the arrangement of the pole teeth in the present invention is not limited to the illustrated state, and should be appropriately set according to the magnetic pole arrangement of the magnet 2.

The wiring (not shown) of each coil 10 is composed of the pole teeth 1.
It extends outwardly through the spaces 2A, 14A, 18A, 20A. Further, cylindrical members 16 and 22 for fixing the outer yoke members 14 and 20, respectively, are fixed to the step portion 8A on the outer side of the bobbin member 8, and the shaft 1 passes through one member 22 to the outside. Have been extended to.

According to the stepping motor having the above structure, since the coil 10 is arranged on both sides of the magnet 2 in the axial direction, the outer diameter of the coil 10 and thus the outer diameter of the motor can be reduced.

A bearing 4 for supporting the shaft 1 is arranged between the magnet 2 and each coil 10, and the coil 10 and the yoke members 12 and 14 or 18 and 20 are fixed to the bearing 4. Since 8 is fixed, it is not necessary to provide a case for accommodating the above-mentioned parts and positioning them relative to each other. Therefore, the yoke members 12, 1
4, 18, 20 pole teeth 12A, 14A, 18A, 20A
The wiring of each coil 10 can be pulled out from the gap of
The degree of freedom of wiring is high, and wiring is easy even when, for example, motors are arranged at high density.

Further, since the distance between the magnet 2 and the bearing 4 is small, the shaft 1 can be shortened by that much, and there is an advantage that the cost can be reduced. It should be noted that the present invention is not limited to the above-mentioned embodiment, and the details may be appropriately changed as necessary.

[0018]

As described above, since the stepping motor according to the present invention has the structure in which the coils are arranged on both sides of the magnet in the axial direction, the outer diameter of the coil and thus the outer diameter of the motor can be reduced.

Further, bearings for supporting the shaft are arranged between the magnet and each coil, and the bobbin member to which the coil and the yoke are fixed is fixed to these bearings. There is no need to provide a case for positioning. Therefore, the wiring of each coil can be drawn out from the gap between the pole teeth of the yoke member, the degree of freedom of wiring is high, and the wiring is easy even when the motors are arranged at high density.

[Brief description of drawings]

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

FIG. 2 is a transverse sectional view of the stepping motor.

FIG. 3 is a sectional view taken along the line III-III in FIG.

[Explanation of symbols]

 1 shaft 2 magnet 4 metal bearing 8 bobbin member 10 coil 12,18 inner yoke member 14,20 outer yoke member 12A, 14A, 18A, 20A pole teeth

Claims (1)

[Claims] 1. A shaft to which a cylindrical magnet is coaxially fixed, a pair of bearings disposed adjacent to both sides of the magnet in the axial direction and rotatably supporting the shaft, and extending to the opposite side of the magnet. A cylindrical bobbin member made of a soft magnetic material and coaxially fixed to each of the bearings, a coil arranged on the outer periphery of each of the bobbin members, and a magnet fixed to both ends of each bobbin member. And a yoke member made of a soft magnetic material having pole teeth extending in a position facing the outer peripheral surface of the stepping motor.