JPH0638499A - Stepping motor - Google Patents

Abstract

(57) [Summary] [Purpose] Despite its simple structure, it is easy to assemble,
It is possible to reduce the number of parts, improve the motor characteristics, and suppress variations in the motor characteristics. [Structure] A rotor 11 composed of a permanent magnet is attached to a stator 2
It can be attracted and rotated by the electromagnetic force created by 0,
In a permanent magnet type stepping motor having a support means 22 for rotatably supporting the shaft 14 fixed to the rotor 11, the support means 22 being fixed in relation to the stator 20, the support means 22 and the stator 20.
Is a stepping motor integrated by molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a stepping motor which can be used as an intermittent drive source, for example.

[0002]

2. Description of the Related Art A conventional permanent magnet type stepping motor, so-called PM (Permanent Magnet).
The stepping motor of the type has a rotor 1, a stator 2, a frame 3, a shaft 4, slide bearings 5 and 9, and a case 6 as shown in FIG. The rotor 1 is a magnet, and the stator 2 has pole teeth 7 and windings 8. A shaft 4 is fixed to the rotor 1, and the rotor 1 is rotated by the electromagnetic force generated by the winding 8 of the stator 2. The shaft 4 is supported by slide bearings 5 and 9. These slide bearings 5 and 9 are attached to holes provided at both ends of the frame 3, respectively, and the shaft 4 is inserted into the slide bearings 5 and 9 and rotatably supported.

[0003]

However, the rotor 1 of this type of stepping motor has a gap 1a with the stator 2.
Is about 150 to 200 μm, which is very small. This void 1a has the following (1), (2), (3)
In this case, the stator 2 and the rotor 1 come into contact with each other, and the rotor 1 does not rotate. (1) When the rotor 1 and the stator 2 are misaligned. (2) When the bearings 5 and 9 are misaligned and each bearing is tilted. (3) When the stator 2 is tilted.

In order to prevent the rotor 1 from rotating due to the contact between the stator 2 and the rotor 1 due to the above-described factors, the dimensional accuracy and the assembly accuracy of each component are greatly improved. There must be. If the dimensional accuracy and the assembly accuracy of each individual component are poor, the assembly cannot be performed. Further, if the air gap is set to be large so that the rotor 1 and the stator 2 never contact each other, there is a problem that the characteristics of the stepping motor are adversely affected.

In order to solve the above problems, the present invention provides a stepping motor which is easy to assemble, can reduce the number of parts, and can improve motor characteristics and suppress variations in motor characteristics. With the goal.

[0006]

In order to solve the above-mentioned problems, according to the present invention, a rotor composed of a permanent magnet can be attracted and rotated by an electromagnetic force generated by a stator and is fixed to the rotor. A stepping motor of the permanent magnet type having a support means for rotatably supporting the shaft, the support means being fixed in relation to the stator, the support means and the stator being integrated by molding. Achieved by the motor.

The supporting means is preferably formed to extend in a direction parallel to the axial direction of the shaft.

The shaft is preferably rotatably supported by a bearing set on the support means side and a bearing set on the stator.

The stator is preferably housed in a case.

[0010]

According to the above construction, since the support means (preferably the frame 22 in the embodiment) and the stator are integrated, it is possible to reduce the number of single-point parts to assemble. Since the support means and the frame are integrated in advance, the rotor, the shaft and the stator are unlikely to be misaligned during assembly, and the rotor and the stator do not come into contact with each other even if the gap formed between the rotor and the stator is small.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings. The examples described below are
Since it is a preferred specific example of the present invention, various technically preferable limitations are attached, but the scope of the present invention is, unless otherwise stated to limit the present invention, in the following description.
It is not limited to these modes.

FIG. 1 shows a preferred embodiment of the stepping motor of the present invention. The stepping motor 10 of the embodiment has a rotor 11, a stator assembly 12, a shaft 14, plain bearings 15 and 19, and a case 16.

The rotor 11 is a permanent magnet and is fixed to one end of the shaft 14. The stator assembly 12 includes a stator 20 and a frame 22, which are integrally formed by molding. This stator assembly 12
Are preferably made of PBT (polybutylene terephthalate) or PPS (polyphenylene sulfide). The stator 20 has pole teeth 24 and windings 26. The frame 22 is a support means for supporting the shaft 14 and the slide bearings 15 and 19.

The stator 20 of the stator assembly 12 is contained in or surrounded by the case 16. Frame 2 of this stator assembly 12
2 is formed so as to extend in the axial direction of the shaft 14. The slide bearing 15 is fitted into and attached to a hole 28 formed in a connecting portion 34 between the stator 20 and the frame 22. In addition, slide bearing 1
9 is fitted and attached to a hole 30 formed at the tip of the frame 22. The shaft 14
Is rotatably supported between the slide bearings 15 and 19.

As described above, the stator 20 and the frame 2 are previously prepared.
By integrally forming 2 and providing the stator assembly 12, the central axes of the slide bearings 15 and 19 can be accurately aligned at the time of assembly.
So-called misalignment of each central axis of 9 can be significantly suppressed. Further, the mounting posture of the stator 20 with respect to the frame 22 can be improved. That is, the shaft 14,
Misalignment between the rotor 11 and the stator 20 can be prevented as much as possible, and even if the gap 32 formed between the rotor 11, that is, the magnet and the pole teeth 24 of the stator 20 is set to be narrow, the rotor 11 and the stator 20 are Do not touch. For this reason, when the rotor 11 is rotated by the electromagnetic force generated by the winding wire 26 of the stator 20 without rotation, the rotor 11 can be rotated with high accuracy, so that the characteristics of the stepping motor 10 can be improved.

In the embodiment shown in FIG. 1 of the present invention, regarding the number of parts, the stator 20 and the frame 22 are
By integrating the above, it is possible to reduce the number of parts by one compared with the conventional one, and it is possible to reduce the assembly work time and the assembly work equipment.

[0017]

As described above, according to the present invention,
Since the supporting means and the stator are integrally formed, the number of parts can be reduced by one and the stepping motor can be easily assembled. Therefore, it is possible to reduce the jig for assembling and the equipment for assembling. Then, even if the gap formed between the rotor and the stator is set to be narrow, the rotor and the stator do not come into contact with each other, and it is possible to improve the motor characteristics and suppress variations in the motor characteristics.

[Brief description of drawings]

FIG. 1 is a sectional view showing a preferred embodiment of a stepping motor of the present invention.

FIG. 2 is a cross-sectional view showing a conventional stepping motor.

[Explanation of symbols]

 10 Stepping Motor 11 Rotor 12 Stator Assembly 14 Shaft 15 Sliding Bearing 19 Sliding Bearing 20 Stator 22 Frame (Supporting Means) 24 Pole Teeth 26 Winding 32 Gap

Claims (4)

[Claims] Claim: What is claimed is: 1. A rotor comprising a permanent magnet, which can be rotated by being attracted by an electromagnetic force generated by the stator, and which is provided with a supporting means for rotatably supporting a shaft fixed to the rotor. In a permanently fixed permanent magnet type stepping motor, the supporting means and the stator are integrated by molding. 2. The stepping motor according to claim 1, wherein the supporting means is formed to extend in a direction parallel to the axial direction of the shaft. 3. The stepping motor according to claim 1, wherein the shaft is rotatably supported by a bearing set on the support means side and a bearing set on the stator side. 4. The stepping motor according to claim 3, wherein the stator is housed in a case.