JPH03128657A - Stator yoke for small-sized motor - Google Patents

Abstract

PURPOSE:To improve the stop positional accuracy of a rotor by fitting a central opening with a cylindrical constituent formed through juxtaposing a plurality of tongue-shaped parts of the same shape extending axially, of which circumferentially adjacent parts forming a pair are directed oppositely to each other, at a predetermined pitch with a peripheral wall. CONSTITUTION:A cylindrical constituent 2 is constituted when predetermined tongue-shaped parts 2a are formed in a belt-like flat plate composed of mild steel material with a predetermined width by press working and thereafter the flat plate is rounded into a cylindrical body. In this case, the cutting edges of the belt-like flat plate are selected in the manner of coinciding with the center line of punching grooves for forming the tongue-shaped parts. Thus, an apparatus can be assembled easily when an outer peripheral ring 1 and a disc 3 are respectively fitted to one side and the other side with the cylindrical constituent 2 between.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a stator yoke structure particularly suitable for small motors.

[Conventional technology]

In recent years, PM type stepping motors have been used in large quantities as drive sources for FDD magnetic heads and printers in OA equipment, but as OA equipment has become smaller and more sophisticated, they have become smaller and thinner, lower in cost, and lower in noise. , demands for higher torque are becoming stronger.

In a conventional stepping motor of this kind, for example, as shown in FIG. 8, the center part of an outer circumferential ring 4 and a washer-like disk 5 having the same diameter are punched radially inward as a stator yoke. Remaining tongue-shaped portion 4a.

5a is bent in the axial direction, and the outer ring 4 and the washer-like disk 5 are combined so that these tongue-like portions are alternately arranged on the same circumference and constitute magnetic poles. was.

[Problem to be solved by the invention]

By the way, in the stator yoke having the above structure, it is difficult to make the arrangement pitch of the magnetic poles uniform with high precision due to the unevenness of the tongues 4a and 5a due to bending. was difficult.

In addition, the cylindricity of the cylinder formed by the tongues, that is, the magnetic poles, cannot be expected to be highly accurate because it is difficult to bend each tongue at a right angle. It had to be about 0.15 to 0.2M, and there were difficulties in achieving a smaller size and higher torque. In addition, increasing the axial length of the stator yoke is a necessary condition for miniaturization and high torque, but the thickness, shape, and length of the tongue-like portion, that is, the magnetic pole, are determined by the thickness of the outer ring and washer-like disk. There was a drawback that this request could not be met because it was restricted by the outer diameter of the sheath. Further, although this type of stator yoke is generally subjected to magnetic annealing after assembly, the above-mentioned problems may be exacerbated because thermal deformation occurs during this process.

SUMMARY OF THE INVENTION An object of the present invention is to provide a stator yoke for a small motor of this type that can solve the above-mentioned problems at once and is easy to manufacture.

[Means and operations for solving the problem] In order to achieve the above object, the stator yoke of the present invention has a central opening concentrically and the same diameter provided in an outer ring and a disk having the same diameter as the outer ring, respectively.
At least one sheet of tongue-shaped portions having the same shape and extending in the axial direction on the peripheral wall and arranged in parallel at a predetermined pitch in both central openings, with pairs of tongue-shaped portions adjacent to each other in the circumferential direction facing oppositely to each other. It is constructed by fitting a cylindrical structure, and its plurality of tongues are used as magnetic poles.

The cylindrical structure may be provided with at least two sets of the plurality of tongues arranged in parallel in the circumferential direction and shifted by a half pitch from each other.

The cylinder to become the stator magnetic pole is formed by pressing a belt-like flat plate to form a plurality of tongue-shaped parts and then viewing it, if it is made from a plurality of cylindrical members, or by forming a plurality of cylindrical members If it is made from a body, it is formed by pressing a plurality of flat plates to form a plurality of tongue-shaped portions, respectively, and then curving these into an arcuate shape and then combining them.

〔Example〕

Hereinafter, one embodiment of a stator yoke for a small motor according to the present invention will be described with reference to FIGS. 1 and 2. In the figure, l denotes an outer ring in which a central opening 1a is formed by squeezing a disc-shaped blank made of mild steel into a cup shape by press working, and 2 denotes a pair of circumferentially adjacent rings extending in the axial direction on the peripheral wall. The cylindrical structure 3 is made of mild steel and is fitted into the center opening 1a of the outer ring 1, with a plurality of tongues 2a of the same shape arranged in parallel at a predetermined pitch such that the tongues are in opposite directions. The center opening 1a of the outer ring l is formed by press processing so that it has the same outer diameter as the outer ring l.
It is a circular plate in which a central opening 3a having the same diameter as is formed.

As shown in FIG. 2, the cylindrical structure 2 is made by forming a predetermined number of tongues 2a on a belt-shaped flat plate made of mild steel with a predetermined width by press working, as shown in FIG. It is constructed by rolling it into a cylinder, but the length of this cylindrical structure, that is, the belt-like flat plate, may be selected so that a cylinder with a predetermined diameter is formed when viewed after pressing, or it may be formed by rolling a plurality of sheets. The length may be selected such that a cylinder with a predetermined diameter is formed by combining the strip-like flat plates. Furthermore, this belt-like flat plate, that is, the cylindrical structure 2, has a plurality of tongue-like parts 2, as shown in FIG.
a may be shifted by half a pitch from each other to form two upper and lower rows, or two or more rows may be provided. In any of the above cases, it is preferable that the cut edge of the flat strip be selected so as to coincide with the center line of the punched groove for forming the tongue (see FIGS. 2 and 3).

Since the stator yoke according to the present invention is composed of the above-mentioned components, the cylindrical structure 2 which is rounded into a cylindrical shape or combined into a cylindrical shape is sandwiched between the outer ring l on one side and the outer ring l on the other side. By simply fitting the plate 3, it can be easily assembled into the state shown in FIG. 4. In this case, the exciting coil C is placed in the annular space between the peripheral wall of the outer ring l and the peripheral wall of the cylindrical structure 2.
is inserted in the same way as in the conventional case, but the magnetic poles for rotating the magnet rotor R are formed in a concentrated manner, particularly at the tip portion of each tongue-shaped portion 2a. Figures 5 to 7 show the cylindrical structure 2.
This figure shows various different combination structures of the outer circumferential ring 1, the cylindrical structure 2, and the disc 3 in which two tongue-like portions 2a are provided. P in FIG. 5 indicates a magnetic shielding plate.

〔Effect of the invention〕

As described above, according to the present invention, since both the outer ring 2 cylindrical structure and the disk, which are the component parts, are obtained from a flat plate by simple press working, not only can extremely high processing accuracy be maintained, Since it is extremely easy and simple to assemble, it can also be used as a stator yoke with high dimensional accuracy in the entire axial direction, making it possible to further reduce the gap between the rotor and stator magnetic poles, and improving rotor stopping position accuracy. This makes it possible to provide a stepping motor with extremely high performance. In addition, the length and plate thickness of the cylindrical member that becomes the magnetic pole are not limited by the outer diameter or plate thickness of the outer ring. Since the shape can be arbitrarily selected, it is also possible to provide a stepping motor with a high torque considering its outer diameter. According to experiments conducted by the applicant, by reducing the gap mentioned above and appropriately selecting the axial length of the cylindrical component, it is possible to increase the torque by approximately 40% compared to conventional products with a stepping motor of the same diameter. It was confirmed that there is. Furthermore, according to the present invention, since the outer ring 9 cylindrical structure and disk can be assembled after being magnetically annealed, distortion and deformation will not occur as a result of stator yaw, and an extremely homogeneous high-performance compact stepping motor can be produced. It can be provided at a lower price (approximately 20% lower cost than conventional products).

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of an embodiment of the stator yoke according to the present invention, FIG. 2 is a developed view of the cylindrical structure shown in FIG. 1,
FIG. 3 is a developed view showing another embodiment of the cylindrical structure, FIG. 4 is a sectional view showing the assembled state of the stator yoke shown in FIG. 1, and FIGS. 5 to 7 are shown in FIG. 3. FIG. 8 is an exploded perspective view showing an example of a conventional stator yoke. l...outer ring, 1a...center opening, 2...
Cylindrical structure, 2a...tongue, 3...disc, 3
a... Engraving of figure = Figure 1 Figure drawing, 7; Target drawing for stator yoke 5° correction

Claims (2)

[Claims] (1) A peripheral ring and a disk having the same diameter as the peripheral ring are each provided with central openings having the same center and the same diameter, and in both central openings, a pair of peripheral walls extending in the axial direction and adjacent in the circumferential direction are opposite to each other. By fitting at least one cylindrical structure consisting of a plurality of tongue-shaped parts having the same shape and oriented in parallel at a predetermined pitch, and joining the outer circumferential ring and the disk, the tongue can be formed. A stator yoke for small motors whose shaped parts are used as magnetic poles. (2) The stator yoke according to claim (1), wherein the cylindrical structure is provided with at least two sets of the plurality of tongue-shaped parts arranged in parallel in the circumferential direction and shifted by a half pitch from each other. .