JPH11346469A - Stepping motor with speed-changing mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of components and manufacturing processes of a stepping motor with a speed changing mechanism which are used in various OA equipment. SOLUTION: In a stepping motor with a speed-changing mechanism, in which an internal gear 17 is installed side by side with a stator assembly 28, and the rotating speed of a rotor 8 is changed by means of the internal gear 17 and planet gears 25, 26 geared with the internal gear 17, the internal gear 17 and the stator assembly 18 are formed of a synthetic resin as an integral body. With this method, the number of components, which has been large in the conventional method because the stator assembly 28 and the internal gear 17 were separate bodies, can be reduced and thereby the assembling time can also be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor with a speed change mechanism used for various OA equipment and the like.

[0002]

2. Description of the Related Art In a stepping motor with a speed change mechanism (hereinafter simply referred to as "stepping motor") used for OA equipment, etc., the rotational speed of the rotor is not used as it is,
In some cases, the transmission is used by changing the speed by a transmission mechanism. Although a gear is used as a transmission mechanism for this purpose, there is a demand that the overall size be not increased. Therefore, a structure using a planetary gear and an internal gear is adopted.

A conventional structure of a stepping motor 1 using a planetary gear and an internal gear will be described with reference to FIG. 5 and FIG. The stepping motor 1 includes a motor body 2 and a transmission mechanism 3. The motor body 2 has coils 6 and 7 wound around lower and upper stator yokes 4 and 5, respectively. The rotor 8 composed of the magnet and the rotor sleeve is positioned to constitute a claw-pole structure two-phase PM stepping motor.

[0004] The rotor 8 is mounted on a rotating shaft 9.
The rotating shaft 9 is rotatably supported by a bearing 11 provided on a bearing housing plate 10 and a bearing 13 provided on a front plate 12. The upper end of the rotating shaft 9 protrudes into the transmission mechanism 3, and a sun gear 14 is attached to the protruding portion. In addition,
A spring washer 15 is provided between the bearing 11 and the rotor 8.
Are provided to apply an upward force to the rotor 8.

The transmission mechanism 3 is formed in a container shape with a gear housing 16 provided on the upper portion of the front plate 12. Inside the gear housing 16, two internal gears 17 are provided at a lower portion and an upper portion. , 18 are provided. The boss 19 provided on the lower internal gear 17 is fitted into a hole 20 provided on the front plate 12 to be positioned and attached (see FIG. 6).

With this structure, the lower internal gear 17 does not rotate together with the gear housing 16. On the other hand, the upper internal gear 18 is fixed to an output shaft 21 provided above the rotating shaft 9 by a key 22 (not shown in FIG. 6), and rotates with respect to the gear housing 16. I have. The output shaft 21 is rotatably supported by a bush 23 fitted on the gear housing 16.

On the bottom of the lower internal gear 17 are provided three pins 24 (see FIG. 6).
Four planetary gears 25 and 26 are rotatably fitted in the lower part and the upper part, respectively. These three planetary gears 2
The lower and upper parts 5 and 26 are formed integrally but with different numbers of teeth.

[0008] Both ends of the pin 24 are supported by a pair of carriers 27, 27 provided above and below the planetary gears 25, 26, respectively. Therefore, three planetary gears 2 at the bottom and at the top
5, 26 are rotatable freely, but the mutual positional relationship is not changed. The lower planetary gear 25 meshes with the sun gear 14 attached to the rotating shaft 9 and the lower internal gear 17. The upper planetary gear 26 meshes with the upper internal gear 18.

In the stepping motor 1 having such a configuration, the rotor 8 rotates intermittently by supplying a current to the coils 6 and 7 by a control circuit (not shown). The rotation force rotates the rotating shaft 9, the sun gear 14, the lower planetary gear 25, and the upper planetary gear 26. The lower internal gear 17 meshes with the lower planetary gear 25, but since the internal gear 17 does not rotate integrally with the stator assembly 28, the rotational force of the lower planetary gear 25
Are rotated. When the carrier 27 rotates, the upper planetary gear 26
Rotates in a planetary manner, the rotational force rotates the upper internal gear 18 meshing with the planetary gear, and the output shaft 2 integrated therewith.
Rotate 1 In this case, since the lower and upper internal gears 17 and 18 have different numbers of teeth, deceleration or speed-up shifting is performed.

The sun gear 14, the lower and upper internal gears 17, 18 and the lower and upper planetary gears 25, 2 having the above structure.
6 is made of a thermoplastic resin material generally called engineering plastic, for example, a polyacetal (POM) resin having excellent slidability.

[0011]

The stepping motor 1 operating as described above has no problem in its function, but leaves room for improvement in structure. That is,
When assembling by attaching each gear as the transmission mechanism 3,
The operation of fitting the boss 19 provided on the lower internal gear 17 into the hole 20 provided on the front plate 12 and positioning the boss 19 and achieving concentric accuracy for this purpose is troublesome. The joining work of both parts was complicated. Furthermore, there has been a problem that the number of parts and the number of work steps required for assembly are large in response to recent demands for cost reduction.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and an object of the present invention is to provide a stepping motor with a speed change mechanism in which the structure is simplified without changing the rotation performance, and the number of parts and the number of work steps required for assembly are significantly reduced. Aim.

[0013]

According to the present invention, as means for solving the above-mentioned problems, in the invention described in claim 1, an internal gear is provided side by side on a stator assembly, and the internal gear and the internal gear are provided. In a stepping motor with a speed change mechanism for changing the rotation speed of a rotor by a planetary gear meshing with the stepped motor, the internal gear and the stator assembly are formed integrally by synthetic resin.

According to a second aspect of the present invention, in the first aspect, two internal gears are provided vertically, and the two internal gears and the two internal gears are provided. The gear is shifted by a planetary gear that meshes with the gear at the same time,
The lower internal gear of the two internal gears and the stator assembly are integrally formed of synthetic resin.

In the stepping motor with a speed change mechanism having such a configuration, the rotor rotates by energizing the coil wound around the stator yoke by the control circuit, and the rotation is accelerated by the meshing of the planetary gear and the internal gear. Or it is decelerated.

[0016]

FIG. 1 is a block diagram showing an embodiment of the present invention.
4 to 4, the same members as those shown in FIGS. 5 and 6 are denoted by the same reference numerals and described. 1 is a longitudinal sectional view showing a state in which a gear housing and an output shaft are omitted, FIG. 2 is a longitudinal sectional view showing a stator assembly and a lower internal gear portion in FIG. 1, and FIG. 1 is an exploded perspective view showing a disassembled state, and FIG. 4 is an enlarged longitudinal sectional view of a portion A in FIG.

As shown in FIGS. 1 and 2, coils 6 and 7 are wound around lower and upper stator yokes 4 and 5, respectively, and a stator assembly 28 is formed by these. The coils 6, 7 are connected to lead wires (not shown) by connection terminals 6a, 7a.

A lower internal gear 17 is provided above the stator yoke 5. The stator assembly 28 and the lower internal gear 17 are integrated by installing the lower and upper stator yokes 4 and 5 in a mold (not shown) and injecting and injecting a synthetic resin in a molten state from a gate port 29. I do. Then, the synthetic resin first passes through the inner circumference 30 and the outer circumference 31 of the lower stator yoke 4, flows into the upper stator yoke 5, flows into the end side of the upper stator yoke 5, and The lower internal gear 17 is formed concentrically. At the same time, the bearing housing plate 10
Is also molded.

As a material of the synthetic resin, a thermoplastic resin called engineer plastic, specifically, the sun gear 14, the lower and upper internal gears 17, 18 and the lower part in the conventional structure shown in FIGS. The polyacetal (POM) resin from which the upper planetary gears 25 and 26 are manufactured can be used.
M) Not limited to resin, polycarbonate (PC) resin or polybutylene terephthalate (PBT)
It is possible to mold using a resin, a polyethylene terephthalate (PET) resin, and a polyphenylene sulfide (PPS) resin.

The synthetic resin is supplied to the stator assembly 28 during molding.
At this time, the stator assembly 28 generates heat due to the heat storage effect of the coils 6 and 7 wound around the stator yokes 4 and 5, respectively. Therefore, when the stator assembly 28 and the lower internal gear 17 are integrally formed of a synthetic resin having low heat resistance, the teeth formed on the inner peripheral side of the lower internal gear 17 due to the heat generated by the coils 6 and 7. There is a risk of deformation. Therefore, as a synthetic resin used for integrally molding the lower internal gear 17 and the stator assembly 28, it is necessary to use a resin having excellent heat resistance, and preferably a polybutylene terephthalate (PBT) resin or a polyphenylene sulfide (PBT) resin is used. PPS) resin and the like are preferable.

The stepping motor 1 of the present invention constructed as described above is also provided with coils 6 and 7 by a control circuit (not shown).
, The rotor 8 rotates intermittently.
Then, the movement is transmitted in the order of the rotating shaft 9, the sun gear 14, the lower planetary gear 25, and the lower internal gear 17, but since the lower internal gear 17 does not move, the lower planetary gear 25 is not moved.
Rotates about the rotation shaft 9 and the output shaft 21 together with the pair of upper and lower carriers 27 supporting the pin 24.

As described above, since the lower planetary gear 25 is integral with the upper planetary gear 26, the lower planetary gear 25
At the same time, the upper planetary gear 26 also rotates. This rotation causes the upper internal gear 18 to rotate. Since the output shaft 21 is connected to the upper internal gear 18 by the key 22, the output shaft 2
1 rotates. In this case, since the lower and upper internal gears 17 and 18 have different numbers of teeth, deceleration or speed-up shifting is performed. In the present embodiment, the planetary gears 25 and 26 are divided into upper and lower portions having different numbers of teeth, and are integrally formed. However, the planetary gears 25 and 26 can be used without being divided into upper and lower portions.

[0023]

According to the present invention, there is provided a stepping motor with a speed change mechanism having the above-described structure, in which an internal gear and a stator assembly are integrally formed of synthetic resin. Are provided at the top and bottom, and the speed is shifted by the two internal gears and the planetary gear that meshes with the two internal gears at the same time. Since the stator assembly and the stator assembly are integrally formed of synthetic resin, the number of parts can be reduced, and the work of mounting individual parts during assembly can be omitted. Concentricity with the tooth gear can be easily obtained. Thus, a significant cost reduction effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a portion of a stator assembly and a lower internal gear in FIG. 1;

FIG. 3 is a perspective view showing the disassembled state of FIG. 1;

FIG. 4 is an enlarged longitudinal sectional view of a portion A in FIG. 1;

FIG. 5 is a longitudinal sectional view of a conventional stepping motor.

FIG. 6 is a perspective view showing the disassembled state of FIG.

[Explanation of symbols]

 Reference Signs List 1 stepping motor 4 stator yoke 5 stator yoke 8 rotor 9 rotating shaft 14 sun gear 17 lower internal gear 18 upper internal gear 25 planetary gear 26 planetary gear 26 planetary gear 28 stator assembly

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takayuki Yamawaki 173-1 Asana-cho, Iwata-gun, Shizuoka Prefecture Inside Minebea Electronics Co., Ltd. (72) Inventor Shintake Matsushita 173-1 Asana-cho, Asaba-cho, Iwata-gun, Shizuoka Prefecture Minebea Electronics Corporation

Claims (2)

[Claims] 1. A stepping motor with a speed change mechanism, wherein an internal gear is provided side by side with a stator assembly, and a rotation speed of a rotor is shifted by the internal gear and a planetary gear meshing with the internal gear. A stepping motor with a speed change mechanism, wherein a three-dimensional body and a synthetic resin are formed by integral molding. 2. An internal gear having two internal gears arranged vertically, wherein the two internal gears and a planetary gear that meshes with the two internal gears at the same time perform a speed change. 2. The stepping motor with a transmission mechanism according to claim 1, wherein the lower internal gear and the stator assembly are integrally formed of synthetic resin.