JPS6277855A - Stepping motor - Google Patents

Abstract

PURPOSE:To prevent the vibration of each section of a housing and a plurality of stators by solidifying the stators with a resin, etc. and unifying the stators as the housing. CONSTITUTION:When a stator 1 is molded with a resin, etc. and a housing is formed, a mandrel 52 is fitted into a bottom force 50, the stator 1 is arranged around the mandrel 52, a top force 51 is fitted to the bottom force 50, the resin 60, etc. are injected into a space shaped by the bottom force 50, the top force 51 and the mandrel 52, and they are solidified, and the mandrel 52 may be drawn out of the opening section side after solidification. Accordingly, since the stator 1 is molded with the resin 60, etc. and unified as the housing, each section of the housing and the stator 1 does not vibrate, thus preventing the generation of noises.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a stepping motor in which a rotor is rotated by a predetermined angle by a stator disposed around the rotor.

[Prior art and its problems] In stepping motors used in facsimile machines, floppy disk drives, etc., the air gap between the stator and rotor is made very small, around 60 μm, in order to improve angular accuracy. There is. In order to reduce the air gap in this way, it is required to ensure accuracy in the concentricity of the inner periphery of the stator and the rotor, and the perpendicularity between the rotor axis and the end surface of the housing.

Conventional stepping motors have housings made of steel pipes or die-cast aluminum, and precision machining ensures the above-mentioned accuracy. In this case, there are many processing parts, and
Since it requires sophisticated processing technology, it is very time-consuming and costly to manufacture. Furthermore, since the housing of this stepping motor is made of metal, it also has the disadvantage of generating noise.

Therefore, in order to reduce machining and prevent noise, it is conceivable to mold the stator with resin and integrate it as a housing. However, when the part of the housing to which one bearing is attached is formed by an upper mold, and the part to which the other bearing is attached and the part to accommodate the rotor are formed by a cored metal, the upper part of the housing is formed coaxially. The axes of the mold and core metal must be aligned, but it is very difficult to do this accurately, and because it is not possible to make the bearing and the inner circumferential surface of the stator completely concentric, the rotor and stator It was not possible to reduce the air gap between the two.

Therefore, an object of the present invention is to provide a stepping motor that requires less machining during manufacturing, does not generate noise, and has high precision.

Means for Solving Problem E] In order to solve the above problem, the stepping motor of the present invention is configured as follows. That is, a housing is formed by molding a plurality of stators arranged in a circular shape with resin or the like, and a circular cylinder with a small diameter is provided at one end of the cylindrical rotor housing space inside the housing. The mounting space for columnar bearings is formed coaxially with the rotor housing space, and the other end has a
A cylindrical opening having a diameter larger than the rotor housing space is formed coaxially with the rotor housing space, and the annular bulge of the disc-shaped bracket is fitted into the opening and is housed in the rotor housing space. The rotor is rotatably supported by a bearing installed in the space and a bearing provided at the center of the bracket.

[Function] In the stepping motor of the present invention, the stator is molded with resin or the like and integrated as a housing, and inside thereof, a bearing mounting space, a rotor housing space, and an opening are arranged in order in diameter. If you use one core metal with parts corresponding to each of these parts during molding, after the resin etc. hardens, this core metal can be pulled toward the opening side. You can pull it out without any hassle.

Further, in this stepping motor, since the plurality of stators are solidified with resin or the like and integrated as a housing, each part of the housing and the stator does not vibrate.

[Example 1 Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, reference numeral 1 denotes a plurality of stators arranged in a circular manner, and this stator 1 has a stator core 2 wound with a coil 4 via an insulating spool 3. Teeth 2a are formed. A housing 5 is formed by molding the stator 1 with resin or the like. Inside this housing 5, a space 7 for mounting a cylindrical bearing to which a bearing 6 is attached, a rotor accommodation space 8 having a diameter larger than that of a rotor 20 (described later) by an amount of an air gap, and an opening 9 are successively formed. The rotor accommodating space 8 is formed to have a larger diameter than the space 7 for mounting the bearing, and the opening 9 is formed to have a larger diameter than the rotor accommodating space 8.

The rotor 20 has two rotor yokes 22 and 23 made of a magnetic material with a larger diameter than the permanent magnet 21 sandwiched between them and fixed coaxially to the rotor shaft 24.

That is, one rotor yoke 22 is magnetized to the N pole,
The other rotor yoke 23 is magnetized to the S pole.

A large number of teeth are formed at predetermined angular intervals on the circumferential surface of the rotor yokes 22 and 23, and these two rotor yokes 2
2.23 is fixed so that each tooth is shifted in the circumferential direction so that it is alternated.

Reference numeral 30 denotes a disc-shaped bracket made of aluminum or the like, and a bearing 31 is installed in a hole in the center of the bracket 30.
An annular bulge 32 that fits into the opening 9 of the housing 5 is provided coaxially with the bearing 31 on one side of the bracket 30.

The rotor 20 is rotatably supported within the housing 5 by a bearing 6 installed in a space 7 and a bearing 31 at the center of a bracket 30. Bracket 30 is fixed to housing 5 with screws 35.

This stepping motor rotates by a predetermined angle by sequentially exciting the coils 4 of the stator 1 disposed around the rotor 20.

Next, a method of forming the housing 5 will be explained using FIG. 2.

Reference numerals 50 and 51 are a lower mold and an upper mold that form the outer shape of the housing 5, and 52 is a core metal that forms the mounting space 7, the rotor accommodation space 8, and the opening 9 for the bearing inside the housing 5. The core metal 52 has a circular plate-shaped portion 52a forming the opening 9 side of the housing 5, a cylindrical portion 52b forming the opening 9 of the housing 5, and a circular disk-shaped portion 52b forming the opening 9 of the housing 5. The columnar portion 52C1 bearing is mounted by sequentially forming a columnar portion 52'd forming a space 7, and a columnar portion 52e forming a hole through which the rotor shaft 24 is inserted at the top. It is formed. These parts 52a, 52b, 52c, 52
d, 52e C. The diameters become smaller in sequence from the bottom to the top, so that each of the portions 7, 8.9 inside the housing 5 can be formed by one core metal.

When molding the stator 1 with resin or the like to form the housing 5, first, the core metal 52 is fitted into the lower mold 50, the stator 1 is arranged around the core metal 52, and then the upper mold 51 into the lower mold 50, the lower mold 50, the upper mold 51, and the core bar J2.
The resin 60 or the like may be injected into the space formed by the resin 60 and solidified, and after assimilation, the core bar 52 may be handled from the opening 9 side.

Note that in this embodiment, the opening 9 of the housing 5
is formed to have a larger diameter than the rotor accommodation space 8, but both may be formed to have the same diameter.

[Effects of the Invention] As described above, in the stepping motor of the present invention, the mounting space, the rotor housing space, and the opening of the bearing of the housing are formed by one core metal. If the corresponding parts are formed completely coaxially, each part of the housing will be formed completely coaxially, and one bearing will be installed by forming a space with an upper die, and when installing a rotor, the space will be formed by a core metal. The axes of each part will not shift as would be the case if formed with Therefore, when installing the bearing, the bearing installed in the space, the bearing at the center of the bracket fitted into the opening, and the inner circumferential surface of the rotor housing space are accurately concentric, thereby ensuring that the inner circumference of the stator Since the concentricity of the rotor and the perpendicularity between the rotor axis and the end face of the housing are ensured, the air gap between the rotor and the stator can be made extremely small, and the angular accuracy of the stepping motor can be increased. Further, since machining is not required to ensure such precision, manufacturing can be carried out easily and at low cost.

Further, in this stepping motor, since the stator is molded with resin or the like and integrated as a housing, each part of the housing and stator does not vibrate, so that no noise is generated.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a stepping motor of the present invention, and FIG. 2 is a sectional view showing a method of molding a housing of the same embodiment. Explanation of symbols 1... Stator 2... Stator core 2a... Stator teeth 3... Insulating spool 4... Coil 5...
・・Housing 6・・・・Bearing 7・・
...The bearing is installed in space 8... Rotor housing space 9... Opening 20... Rotor
21... Permanent magnet 22... Rotor yoke 23.
...Rotor yoke 24...Rotor @ 30...
・Bracket 31... Bearing 32... Annular bulge 35... Screw 50... Lower mold 5
1... Upper mold 52... Core bar 60... Resin patent applicant Shibaura Seisakusho Co., Ltd. Figure 1

Claims (1)

[Claims] 1. A housing is formed by molding a plurality of stators arranged in a circle with resin or the like, and a cylindrical bearing with a diameter smaller than that of the rotor accommodating space is installed at one end of the cylindrical rotor accommodating space inside the housing. The mounting space is formed coaxially with the rotor housing space, and at the other end, a cylindrical opening having a diameter larger than the rotor housing space is formed coaxially with the rotor housing space. The annular bulge of the disc-shaped bracket is fitted, and the rotor accommodated in the rotor accommodation space is pivoted freely by the bearing installed in the bearing mounting space and the bearing provided at the center of the bracket. A stepping motor characterized by being supported.