JPH10327570A - Stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the vibration of a stepping motor by making the basic stepping angle of the motor smaller by making trapezoidal pole teeth shorter in length and separating a plurality of yokes from each other so that the yokes may not overlap each other on the same circumference, and then, increasing the number of the pole teeth. SOLUTION: In a stepping motor, coil bobbins 12 are fixed between outer yokes 11 having trapezoidal pole teeth and inner yokes 12. In addition, bearings 16 are fixed to the inner yokes 12. One set of stators 14 is constituted of one outer yoke 11, one inner yoke 12, and one coil bobbin 13. A magnet 15 polarized in multiple poles along its outer periphery exists between two sets of facing stators 14. The stators 14 are separated from each other at the central part of the stepping motor. Accordingly, the pole teeth of the two sets of stators 13 do not overlap each other on the same circumference. Therefore, the number of pole teeth can be increased without providing any space between the pole teeth of the outer yokes 11 and inner yokes 12 for putting the pole teeth of another set of stators 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor used for driving / actuating an OA device such as a printer and a floppy disk drive, and an AV device such as a video movie.

[0002]

2. Description of the Related Art Conventionally, as the above-mentioned stepping motor, a motor described in JP-A-62-118752 is known.

FIG. 8 shows a conventional stepping motor.
A stator 84 is formed by sandwiching a coil bobbin 83 between an outer yoke 81 and an inner yoke 82 made by sheet metal working, and has a structure in which a magnet 85 is inserted between two sets of stators 84.

The trapezoidal pole teeth of the two sets of stators 84 are alternately arranged on the same circumference.

[0005]

SUMMARY OF THE INVENTION In a stepping motor, low vibration is required. However,
In the above-described conventional configuration, the pole teeth of the two outer yokes and the two inner yokes are arranged on the same circumference, so that the number of pole teeth of one yoke is 4 which is the total number of pole teeth existing on the same circumference. It's a fraction.

For this reason, the basic step angle of the conventional motor is large, and the vibration during the rotation of the motor may be large. Accordingly, the advantages of small size and small diameter cannot be fully utilized, and there has been a great demand for low vibration.

An object of the present invention is to provide a stepping motor having small vibration by increasing the number of pole teeth, reducing the basic step angle, and smoothly rotating the motor.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention shortens the trapezoidal pole teeth and separates the two stators so that the four yokes do not overlap on the same circumference.
The number of pole teeth is doubled. Thus, a stepping motor having a small basic step angle and small vibration can be obtained.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention comprises two sets of stators each including a coil bobbin, an inner yoke having a plurality of pole teeth, and an outer yoke having a plurality of pole teeth. A stepping motor in which a rotor having a magnet with multipolar magnetization applied to the outer periphery thereof opposed to the pole teeth is disposed inside two sets of stators, and the coil bobbins are arranged on both sides of an end face of the rotor. The two sets of stator pole teeth are configured so as not to intersect each other in the axial direction. As a result, the two sets of stators are separated from each other at the center of the motor, and the number of trapezoidal pole teeth included in one yoke is の of the total number existing in the same circumference. Increasing the total number of pole teeth has the effect of reducing the basic step angle and reducing motor vibration.

According to a second aspect of the present invention, the dimensions of the root and the tip of the pole teeth are equalized. This has the effect of increasing the area of the pole teeth facing the magnet and improving the torque.

According to a third aspect of the present invention, a gap larger than a gap between the magnet of the rotor and the inner diameter of the stator is provided between the two sets of stators. Thus, the two sets of stators are magnetically separated, so that the leakage magnetic flux between the two sets of stators is suppressed, and the responsiveness of the stepping motor is improved.

According to a fourth aspect of the present invention, the coil bobbin, the inner yoke, and the outer yoke are integrally molded with resin.
As a result, the gap between the adjacent outer yoke and inner yoke is covered with the resin, so that foreign matter can be prevented from being mixed. Further, since the outer yoke, the inner yoke, and the coil bobbin are fixed with the resin, vibration can be reduced. And the function of easily fixing the position of the inner yoke in the rotation direction.

According to a fifth aspect of the present invention, from the tip of the pole teeth,
It is configured such that it is covered with resin up to half the height of the gap between the two sets of stators. Thereby, when the two sets of stators are combined, the gap between the stators is covered over the entire circumference by the resin, which has an effect of preventing foreign matter from being mixed.

According to a sixth aspect of the present invention, two sets of stators are provided with a concave portion at one of the resin portions protruding from the tips of the pole teeth and a convex portion at a position corresponding to the other concave portion. is there. Thus, the two sets of stators are fixed by fitting the convex portions to the concave portions, and have an effect that the two stators can be easily positioned in the rotational direction.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) In FIG. 1, a coil bobbin 13 is fixed between an outer yoke 11 and an inner yoke 12 having trapezoidal pole teeth. The inner yoke 12 has a bearing 1
6 is fixed. One outer yoke 11, one inner yoke 12, and one coil bobbin 13 constitute a set of stators. A magnet 15 multipolarly magnetized on the outer periphery exists between two pairs of stators 14 facing each other. The two sets of stators 14 are separated at the center of the motor. This prevents the pole teeth of the two stators 14 from overlapping on the same circumference, so that the pole teeth of the other stator 14 are located between the pole teeth of the outer yoke 11 and the pole teeth of the inner yoke 12. There is no need to provide a gap, and the number of pole teeth can be increased.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.

In FIG. 2, the total number of pole teeth is the same as in the configuration of FIG. The difference from the configuration of FIG. 1 is that the dimensions of the root and the tip of the pole teeth of the pole teeth are equal, and the shape is not a trapezoid but a straight shape.

Embodiment 3 Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.

In FIG. 3, the total number of pole teeth is the same as in the configuration of FIG. The difference from the configuration of FIG.
When combining the sets, a gap ΔG is provided between the two sets of stators that is equal to or larger than the gap between the magnet and the inner diameter of the stator.

(Embodiment 4) Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings.

In FIG. 4, the total number of pole teeth is the same as in the configuration of FIG. The difference from the configuration of FIG. 1 is that the outer yoke, the inner yoke,
This is a point that was integrally molded at 1.

(Embodiment 5) Hereinafter, a fifth embodiment of the present invention will be described with reference to the drawings.

In FIG. 5, the stator has the same configuration as that of FIG. The difference from the configuration of FIG. 4 is that when the coil bobbin and the yoke are integrally molded with the resin, the coil bobbin and the yoke are configured to be covered with the resin from the tip of the pole teeth to a height Δh that is half the gap between the two sets of stators. It is.

(Embodiment 6) Hereinafter, a sixth embodiment of the present invention will be described with reference to the drawings.

In FIG. 6, the stator has the same configuration as that of FIG. The difference from the configuration of FIG. 4 is that when the coil bobbin and the yoke are integrally molded with resin, a resin portion protruding from the tip of the pole teeth is provided with an uneven fitting portion.

[0027]

As is apparent from the above embodiment, the first aspect of the present invention is as follows.
According to the described invention, two sets of stators are separated, and the number of trapezoidal pole teeth of one yoke is １ of the total number present in the same circumference, the basic step angle is small, It is possible to realize a stepping motor with small motor vibration.

According to the second aspect of the present invention, the root and the tip of the pole teeth are made equal in size and the shape is made straight. This has the effect of increasing the area of the pole teeth facing the magnet and improving the torque.

According to the third aspect of the present invention, in a stator in which one outer yoke, one inner yoke and one coil bobbin are combined, when the two sets of stators are combined, a magnet and a magnet are provided between the two sets of stators. , And a gap ΔG larger than the gap between the inner diameter of the stator and the inner diameter of the stator. This magnetically separates the two sets of stators,
This has the effect of suppressing the leakage flux between the two sets of stators and improving the responsiveness of the stepping motor.

According to the fourth aspect of the present invention, the coil bobbin and the yoke are molded integrally with resin. As a result, the gap between the outer yoke and the inner yoke is covered with resin to prevent foreign matter from being mixed, and the outer yoke, the inner yoke, and the coil bobbin are fixed with the resin, thereby reducing vibration. It has the effect of facilitating fixing.

According to the fifth aspect of the present invention, when the coil bobbin and the yoke are molded integrally with the resin, the coil bobbin and the yoke are moved from the tip of the pole teeth by two.
It is arranged so that it is covered with resin to a height Δh which is half the gap between the stators of the set. Thereby, since the gap between the two sets of stators is covered with the resin over the entire circumference, there is an effect that foreign matter can be prevented from being mixed.

According to the sixth aspect of the present invention, when the coil bobbin and the yoke are integrally molded with the resin, the resin portion protruding from the tip of the pole teeth is provided with an uneven fitting portion. Thereby, the two sets of stators are fixed by the fitting portion, and there is an effect that the two sets of stators can be easily positioned.

[Brief description of the drawings]

FIG. 1 is a perspective view of a stepping motor according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a stepping motor according to a second embodiment of the present invention.

FIG. 3 is a perspective view of a stepping motor according to a third embodiment of the present invention.

FIG. 4 is a perspective view of a stepping motor according to a fourth embodiment of the present invention.

FIG. 5 is a perspective view of a stepping motor according to a fifth embodiment of the present invention.

FIG. 6 is a perspective view of a stepping motor according to a sixth embodiment of the present invention.

FIG. 7 is a sectional view of a stepping motor according to the first embodiment of the present invention.

FIG. 8 is a perspective view of a conventional stepping motor.

FIG. 9 is a sectional view of a conventional stepping motor.

[Description of Signs] 11, 71, 81 Outer yoke 12, 72, 82 Inner yoke 13, 73, 83 Coil bobbin 14, 84 Stator 16, 75 Bearing 15, 74, 85 Magnet 41 Resin 76 Thrust washer 77 Shaft

Claims (6)

[Claims] 1. A stator comprising two sets of a coil bobbin, an inner yoke having a plurality of pole teeth, and an outer yoke having a plurality of pole teeth, wherein the two sets of stators face the pole teeth. In a stepping motor in which a rotor having magnets subjected to multipolar magnetization is arranged on the outer periphery, and the coil bobbins are arranged on both sides of the end face of the rotor, the pole teeth of the two sets of stators intersect each other in the axial direction. A stepping motor characterized by being constructed without any. 2. The stepping motor according to claim 1, wherein the dimensions of the root and the tip of the pole teeth are equal. 3. The stepping motor according to claim 1, wherein a gap larger than a gap between the magnet of the rotor and the inner diameter of the stator is provided between the two sets of stators. 4. The stepping motor according to claim 1, wherein the coil bobbin, the inner yoke, and the outer yoke are formed integrally with resin. 5. A structure in which the resin is covered from the tip of the pole teeth to half the height of the gap between the two sets of stators with resin.
The stepping motor as described. 6. The stepping motor according to claim 4, wherein a concave portion is provided on one of the resin portions protruding from the pole tooth tips of the two stators, and a convex portion is provided at a position corresponding to the other concave portion.