JP2750065B2 - Stepping motor - Google Patents

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 outer diameter of a motor and facilitating wiring to a coil.

[0002]

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

[0003] A stepping motor used in such an application is particularly required to have a small diameter of the motor so as to increase the arrangement density, and to facilitate coil wiring even when the arrangement density is high. .

[0004]

By the way, in a commonly used stepping motor, a structure in which a pair of coils are arranged so as to surround an outer periphery of a magnet is generally used. There is a problem that the diameter is inevitable, and it is difficult to satisfy the above conditions.

Therefore, the present inventors have proposed a configuration in which coils are arranged on both sides in the axial direction of a magnet and yokes extending from both ends of the coils to positions facing the outer periphery of the magnet are provided to reduce the outer diameter of the motor. Invented.

However, in this case, the outer periphery of the coil and the magnet is covered with a case as in a conventional motor, and the shaft is supported by bearings fixed to both ends of the case.
A hole must be formed in the end face of the case to draw out the coil wiring. If a motor is arranged at a high density, the wiring work of the coil is difficult, and there is a problem that it is difficult to satisfy the above conditions.

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

[0008]

SUMMARY OF THE INVENTION A stepping motor according to the present invention comprises a shaft on which a columnar magnet is coaxially fixed, and is disposed adjacent to both axial sides of the magnet to rotatably support the shaft. A pair of bearings, a cylindrical bobbin member made of a soft magnetic material fixed coaxially to each bearing so as to extend on the opposite side to the magnet, and coils respectively arranged on the outer periphery of these bobbin portion members, it was and a soft magnetic steel yoke member having said been respectively fixed to both ends of the bobbin member extending to the outer peripheral surface opposite to the position of the magnet pole teeth
The bobbin including the coil and the yoke member
By fixing the members to the bearings,
It is characterized by mutual positioning.

[0009]

Since the stepping motor has a structure in which coils are arranged on both sides in the axial direction of the magnet, the outer diameter of the coils and, consequently, the outer diameter of the motor can be reduced. In addition, a bearing that supports the shaft is disposed between the magnet and each coil, and a bobbin member to which the coil and the yoke are fixed is fixed to these bearings. There is no need to provide Therefore, the wiring of each coil can be drawn out from the gap between the pole teeth of the yoke member, the wiring has a high degree of freedom, and the wiring is easy even when the motors are arranged at 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, on the outer periphery of which a plurality of (in this example, four poles) magnetized columnar magnets 2 are fixed via a pair of ring plates 6. A pair of metal bearings 4 that rotatably support the shaft 1 are arranged adjacent to both sides of the magnet 2 in the axial direction.
A cylindrical bobbin member 8 made of a soft magnetic material is coaxially fixed so as to extend to the opposite side to the magnet 2.

Each of the coils 1 is provided on the outer periphery of the bobbin member 8.
0 is wound, and in this embodiment, the outer diameter of each coil 10 is approximately equal to the outer diameter of the magnet 2. Steps 8A and 8B are formed at both ends of the bobbin member 8, and inner yoke members 12 and 18 are formed at the step 8B on the magnet 2 side (inside).
Outer yoke members 14, 20 are fixed to the outer step 8A, respectively. These yoke members 12, 14, 1
8 and 20 are both made of a soft magnetic material.

The inner yoke member 12 (18) has a short U-shape, and a pair of parallel portions thereof has pole teeth 12A (18A).
And almost parallel to the outer peripheral surface of the magnet 2 in the axial direction half. The outer yoke member 14 (20)
Has a long U-shape, and a pair of parallel portions thereof are pole teeth 14.
A (20A) is almost parallel to the outer peripheral surface of the magnet 2 in the axial direction half.

As shown in FIG. 3, the pole teeth 12A, 14A, 18A, and 20A of the yoke members 12, 14, 18, and 20 are pole teeth 12A and 14A fixed to the same bobbin member 8, respectively.
A, 18A, and 20A are positioned so that the phases thereof are different from each other by 90 °, and the pole teeth facing each other across the magnet 2 are different from each other by 45 ° in phase. However, in the present invention, the arrangement of the pole teeth is not limited to the illustrated state, but should be appropriately set according to the arrangement of the magnetic poles of the magnet 2.

The wiring (not shown) of each coil 10 is
It extends outwardly between 2A, 14A, 18A and 20A. Cylindrical members 16 and 22 for fixing the outer yoke members 14 and 20, respectively, are fixed to the outer step 8A of the bobbin member 8, respectively. Has been extended.

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

A bearing 4 for supporting the shaft 1 is disposed between the magnet 2 and each coil 10, and a bobbin member to which the coil 10 and the yoke members 12 and 14 or 18 and 20 are fixed. Since the fixing member 8 is fixed, there is no need to provide a case for accommodating the above-described 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. The present invention is not limited to the above-described embodiment, and details may be appropriately changed as needed.

[0018]

As described above, the stepping motor according to the present invention 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 coils and, consequently, the outer diameter of the motor can be reduced.

In addition, 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 wiring has a high degree of freedom, and the wiring is easy even when the motors are arranged at high density.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view of the stepping motor.

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

[Explanation of symbols]

 Reference Signs List 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)

(57) [Claims] 1. A shaft on which a columnar magnet is fixed coaxially, a pair of bearings arranged adjacent to both sides of the magnet in the axial direction and rotatably supporting the shaft, and extending on the opposite side to the magnet. As described above, a cylindrical bobbin member made of a soft magnetic material fixed coaxially to each of the bearings, coils disposed on the outer periphery of these bobbin portion members, and the bobbin members fixed to both ends of the bobbin members, respectively. it was and a soft magnetic steel yoke member having pole teeth which extend in a position that faces an outer circumferential surface of the magnet
The bobbin member including the coil and the yoke member
By fixing the bearings to the bearings,
Stepping mode characterized by positioning
Ta.