JP2522940Y2 - 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 an improvement in a yoke unit for accommodating a cylindrical rotor of a stepping motor.

[0002]

2. Description of the Related Art Conventionally, a stepping motor that generates rotational power intermittently has the configuration shown in FIG. That is, the stepping motor 1 is made of a metal having a case 2 formed in a cylindrical shape with a bottom and made of a metal material, and a flange having an outer periphery almost exactly matching the inner diameter of the case 2 so as to be accommodated in the case 2. Yoke unit 3 formed into a substantially cylindrical shape by integrally molding resin-made ring-shaped stator yokes 6a, 6b, 6c with resin bobbin 7.
And a cylindrical rotor portion 4 having an outer diameter slightly smaller than the opening diameter so that the motor 1 can be housed in the opening of the yoke unit 3, the case 2 is closed, and the motor 1 is transferred to various devices. And a mounting bracket 5 having a mounting hole 5a for mounting.

Here, the yoke unit 3 is formed as shown in FIGS. FIG. 4 shows a stator yoke 6 formed of a conductive metal material.
The stator yoke 6 includes a ring-shaped flange portion 8 and a large number of comb-toothed salient pole portions 9 which are erected vertically from the inner peripheral edge of the ring-shaped flange portion 8.

As shown in FIG. 5, a plurality of necessary stator yokes such as 6a and 6b are prepared, and the flange portions 8a and 8b are overlapped to form the respective salient pole portions 9a and 9b.
Combine 9b so as to face outward.

Next, as shown in FIG. 6, a plurality of stator yokes 6a, 6b, 6c are combined and housed in a predetermined molding resin mold, and a bobbin 7 made of a synthetic resin material is molded therearound. Next, the winding is wound 3a around the resin bobbin 7 and the coil is provided, so that the cylindrical yoke unit 3 is formed.

A large number of salient pole portions 9 of the stator yoke are exposed on the inner peripheral surface of the yoke unit 3, and the cylindrical rotor 4 shown in FIG. 3 is received in the yoke unit 3. When the motor 1 is energized, the stepping motor is driven by the
Are rotated intermittently, and the rotation power is transmitted to various devices via the rotor shaft 4a.

[0007]

The inner diameter of the yoke unit 3 is slightly larger than the outer diameter of the rotor 4, so that the rotor can smoothly rotate within the yoke unit 3. It has become.

However, the comb tooth-shaped salient pole portion 9 exposed in the yoke unit 3 is used in a step of winding a coil when forming the coil 3a. And the situation shown in FIG. 7 occurs. That is, FIG. 7 is a cross-sectional view showing the inner surface of the yoke unit 3 in an enlarged manner. For convenience of illustration, FIG.

In the figure, the tip 9a of the upper salient pole portion 9 may bend inward due to an external force tightened by the winding 3a of the winding and may project to the inner surface of the yoke unit 3. Therefore, when the rotor 4 is inserted into the yoke unit 3, the tip 9 a of the salient pole portion 9 abuts against the side surface of the rotor 4, preventing smooth rotation of the rotor 4 or displacing the rotor 4 inside the yoke unit 3. There was a problem that it could not be inserted.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an excellent stepping motor in which a rotor is securely housed inside a yoke unit and can rotate smoothly in the yoke unit. is there.

[0011]

SUMMARY OF THE INVENTION The object of the present invention is to integrate a resin bobbin with a stator yoke so that a large number of comb-shaped salient poles of the stator yoke are exposed on the inner peripheral surface. In the yoke unit of the stepping motor, which is molded into a cylindrical shape, each tip of the comb-shaped salient pole portion is provided with a tapered surface that is gradually inclined toward the outer peripheral direction, and the resin mold portion is formed. Is achieved by a stepping motor configured to cover the respective tapered surfaces at the tips of the comb-shaped salient pole portions.

[0012]

According to the above construction, the tip of the comb-shaped salient pole portion exposed on the inner peripheral surface of the yoke unit is formed with a tapered surface that is gradually inclined toward the outer peripheral direction. The engagement tapered surface is resin-molded. For this reason,
Even if an excessive force is applied inward due to the winding of the winding on the outer periphery of the yoke unit, the tips of the salient pole portions contact and engage with the mold resin and are suppressed. It is prevented from bending and projecting.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail. The yoke unit 13 of this embodiment has the same structure as the above-described conventional yoke unit 3 except for the salient pole portion and the resin mold portion, and is provided with the same reference numeral as each member of the conventional yoke unit 3. Have the same configuration, and thus redundant description will be omitted.

Referring again to FIG. 6, the yoke unit 13 according to the present embodiment is formed by integrally forming a synthetic resin bobbin 17 with the ring-shaped stator yokes 6a, 6b, 6c. On the inner peripheral surface of the cylindrical yoke unit 13, the comb-shaped salient pole portions 19 of the large number of stator yokes 6 are exposed.

FIG. 1 is an enlarged schematic cross-sectional view showing the state of the inner surface of the yoke unit 13 of this embodiment. FIG. 1 shows the yoke unit 13 in a different direction.
In the figure, the comb tooth-shaped salient pole portion 19 of the stator yoke is exposed on the inner peripheral surface of the yoke unit 13.
Its tip is covered with a mold resin 17.

Specifically, engaging tapered surfaces 19a, 19a which are gradually inclined toward the outer peripheral direction of the yoke unit 13 are formed at the respective tips of the comb-toothed salient pole portions 19 as shown in the figure. The engagement tapered surfaces 19a, 19a are also coated with a synthetic resin 17.

The engaging tapered surface of the salient pole portion 19 is formed, for example, by the procedure shown in FIG. FIG. 2 is a cross-sectional view illustrating the method of forming the stator yoke 16 in four stages from top to bottom. A through hole 20 is formed in the vicinity of the center of the conductive metal plate 18 (shown in a), and then pressed from below with a predetermined jig around the through hole 20 (shown in b) to vertically cut the tip of the rising portion. (Illustrated in c). Finally, this rising portion is cut so as to be substantially the same as the numerous comb-shaped salient pole portions 9 shown in FIG. 4 described above, and as shown in FIG. Get. Thus, a tapered surface 19a for engagement is formed at the tip of each salient pole portion 19.

The yoke unit 13 of this embodiment is constructed as described above, and its operation will now be described. In FIG. 1, the comb tooth-shaped salient pole portion 19 of the yoke unit 13 is exposed on the inner peripheral surface of the cylindrical yoke unit 13. Here, when the winding is wound 3a around the resin bobbin 17 molded integrally with the stator yoke 6, the resin bobbin 17 bends inward due to its elasticity. At this time, even if this external force is transmitted to the comb-shaped salient pole portion 19, the comb-shaped salient pole portion 19 is bent inward because the tapered surface 19a at the tip is suppressed by the mold resin 17. Does not protrude.

Thus, the rotor 4 is attached to the yoke unit 13.
When the is inserted, the situation in which the protruding tip of the salient pole portion hinders is effectively avoided, and the rotor 4 can rotate smoothly within the yoke unit.

[0020]

As described above, according to the present invention, the rotor received inside the yoke unit is easily housed without being caught on the inner peripheral surface of the cylindrical yoke unit. An excellent stepping motor that can rotate stably in the unit can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a main part of a preferred embodiment of a yoke unit of the present invention.

FIG. 2 is a sectional view showing a method of forming a stator yoke of the yoke unit of FIG.

FIG. 3 is an exploded perspective view showing a configuration of a stepping motor.

FIG. 4 is a perspective view showing an example of a conventional stator yoke.

FIG. 5 is a sectional view showing a state where a plurality of stator yokes of FIG. 4 are combined;

FIG. 6 is a sectional view of a yoke unit.

FIG. 7 is an enlarged sectional view showing a main part of FIG. 6 in a different direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stepping motor 2 Case 3,13 Yoke unit 4 Rotor 6,16 Stator yoke 7,17 Resin bobbin 9,19 Comb-shaped salient pole part 19a Taper surface for engagement

Claims (1)

(57) [Scope of request for utility model registration] 1. A yoke unit for a stepping motor in which a resin bobbin is integrally molded with a stator yoke to form a cylindrical shape so that a number of comb-shaped salient pole portions of the stator yoke are exposed on an inner peripheral surface. , Each tip of the comb-shaped salient pole portion has a tapered surface inclined toward the outer peripheral direction, and the resin mold portion covers each tapered surface of the comb-shaped salient pole portion tip. A stepping motor, characterized in that: