JPS6019507Y2 - Rotor for small motor - Google Patents

Description

[Detailed description of the invention] This invention is concerned with improving the fixing structure of the rotor magnet of a rotor for a small motor.In particular, it provides a rotor for a small motor that prevents cracking when the rotor magnet is fixed and prevents slip rotation during rotation. It is something to do.

Alnico, barium ferrite, samarium cobalt, etc. are generally used for rotor magnets used in electronic watches, but barium ferrite is particularly preferred from a cost standpoint, as well as materials that can be made smaller structurally and consume less energy. From this point of view, high-performance samarium cobalt is often used.

However, the barium ferrite, samarium cobalt, and other magnets mentioned above are powder-molded magnets that are extremely brittle and break easily.

Conventionally, the method of fixing rotor magnets to the rotor shaft is as follows:
Various methods have been tried, such as (a) direct press-fitting, (b) adhesive fusion, and (c) press-fitting through a bush.
None of the methods were satisfactory in terms of cracking, cost, workability, and fixing force.

This invention solves the conventional problem, and uses a fixing spring as a structure to fix the rotor magnet to the rotor shaft, and the fixing spring fixes the rotor magnet in the radial and axial directions, resulting in a low-cost structure. This solves the problems of rotor magnet cracking and fixing force.

Hereinafter, the present invention will be explained in detail based on examples.

A first embodiment is shown in FIGS. 1 to 3, and a rotor 1 for a small motor is composed of a rotor shaft 10, a rotor magnet 20, and a fixed spring 30.

This rotor shaft 10 has tenons 12 and 13 formed at both ends, a flange 14 at one end, and a rotor pinion 16 at the other end.
is formed.

Here, on the side of the flange 14, there is a parallel flat part 18 with the axis cut out.
and 19 are formed, and the flat parts 18 and 19 are cut out to include the flange part, so that the rotor shaft 10 can be integrally molded with a synthetic resin material using an inexpensive mold that can be inserted in the axial direction. .

The rotor magnet 20 is formed into a cylindrical shape using a powder-molded magnet made of samarium cobalt or the like, and has a through hole 22 formed therein having approximately the same diameter as the outer diameter of the rotor shaft 10, so that it can be inserted into the rotor shaft 10. ing.

The fixing spring 30 is itself made of an elastic member, such as a metal plate, and has a groove 32 formed therein that has approximately the same width as the flat parts 18 and 19 of the a-evening shaft 10.

A pawl projection 34 is formed at the end of this groove 32, and the groove width at the position of the pawl projection 34 is equal to the flat portion 18.1 of the rotor shaft 10.
The thickness is set smaller than the thickness of 9.

With such a configuration, the claw protrusion 34 is attached to the flat portion 18,19.
By engaging with the groove 32, the open end of the groove 32 is elastically deformed and expanded, thereby allowing the rotor shaft 10 to be installed within the groove 32.

Further, the fixed spring 30 includes a fixed piece 36 bent in the axial direction of the rotor shaft 10, and the inner surface of the fixed piece 36 is configured to be able to engage with the outer circumferential surface of the rotor magnet 20.

Next, a method of fixing the rotor magnet 20 to the rotor shaft 10 will be explained.

The rotor magnet 20 is inserted into the rotor shaft 10 from the rotor pinion 16 side, one side of the rotor magnet 20 is engaged with the flange 14, and the fixed spring 30 is engaged with the other side of the rotor magnet 20 as shown in FIG. Then, the claw protrusion 34 of the fixing spring 30 is placed on the flat portion 18, 19 of the rotor shaft 10.

Next, by pressing the fixing piece 36 in the direction of the rotor shaft 10, the pawl protrusion 34 rides on the upper surface of the flat portion 18, 19, and the fixing spring 30 is pushed into the rotor shaft 10.

Then, when the claw protrusions 34 pass through the flat portions 18 and 19 and reach the outer peripheral surface of the rotor shaft 10, the claw protrusions 34 return to their original positions, and at this time, the claw protrusions 34 can grip the rotor shaft 10.

Here, the flat portion 1 of the rotor shaft 10 in the first embodiment is
The lengths of 8 and 19 (excluding the thickness of the flange 19) are set approximately equal to the sum of the axial thicknesses of the rotor magnet 20 and the fixed spring 30, so the rotor magnet 20 is aligned with the rotor axis. Axial fixation is achieved relative to 10.

Further, the fixed piece 36 of the fixed spring 30 is engaged with the outer peripheral surface of the rotor magnet 20, and the rotor magnet 20 is prevented from rotating with respect to the rotor shaft 10 by the frictional force on this engagement surface.

This is because the rotor magnet 20 is a powder molded product, so it is molded with a surface that is easily affected by frictional force, or the outer peripheral surface of the rotor magnet 20 is rarely a perfect circle, and the majority of rotor magnets 20 have an eccentric circular shape. The rotor magnet 20 is molded into
When the rotor magnet 20 rotates, the fixed piece 36 engages with the outer circumferential surface of the rotor magnet 20 to prevent its rotation.

In this way, the rotor magnet 20 is fixed to the rotor shaft 10 in the radial direction.

A powder-molded magnet made of samarium cobalt or the like is brittle against pressing force applied from the center hole toward the outer circumferential surface, but strong against pressing force applied from the outer circumferential surface toward the center.

In this embodiment, the pressing force generated from the outer peripheral surface toward the center is large enough to prevent slip rotation of the rotor magnet 20 by securing the fixing piece 36, and the rotor magnet 20 will not be damaged by this pressing force. .

Note that the shapes of the groove portion 32 and the claw protrusion 34 of the fixed spring 30 are not limited to the shapes shown in the embodiments, and may be of any other shape as long as they can be elastically attached to the flat portions 18 and 19 of the rotor shaft 10. It can also be a shape.

Next, a second embodiment will be explained with reference to FIGS. 4 to 6.

This is an embodiment showing another shape of the fixed spring, and the fixed spring 40 is provided with two fixed pieces 46 and 48 at symmetrical positions with respect to the radial direction of the rotor magnet 20.

In this embodiment, there are two fixed pieces 46 and 48 that elastically press the rotor magnet 20 in the radial direction, so that the fixation of the rotor magnet 20 in the radial direction is stronger than that of the fixed spring shown in the first embodiment. It has a shape.

Reference numeral 42 is a groove, and 44 is a claw protrusion formed at the end of the groove 42.

Note that in the first and second embodiments, only the fixing spring is changed, and the other configurations are the same as those of the first embodiment described above, and the same reference numerals are used for the same components, and descriptions thereof will be omitted.

FIG. 7 shows a third embodiment, in which the fixed spring 50 is slightly curved in the direction of the rotor axis 10, and the axial pressing of the rotor magnet 20 by the fixed spring 50 is elastic pressing. It is a feature.

In this case, since the thickness of the fixed spring 50 in the axial direction of the rotor shaft 10 is substantially thicker than that of the first and second embodiments described above, the lengths of the flat portions 18 and 19 of the rotor shaft 10 are It is necessary to make it slightly longer.

Note that the configuration of this third embodiment other than the above is the same as that of the above-mentioned first embodiment, and a description thereof will be omitted.

As explained above, the present invention relates to an improvement in the structure of fixing the rotor magnet to the rotor shaft in a rotor for a small motor. At the same time, it is fixed in the radial direction by engaging the fixing piece of the fixing spring with the outer circumferential surface of the rotor magnet. This prevents the rotor magnet from slipping relative to the rotor axis, and also allows the rotor magnet to be fixed at low cost. The present invention provides a rotor for a small motor that solves the problems of cracking and fixing force.

[Brief explanation of the drawing]

Figures 1 to 3 show the first embodiment of the present invention.
The figure is a side view of a rotor for a small motor viewed from the rotor pinion direction. FIG. 2 is a sectional view taken along the line A-A in FIG. 1. FIG. 3 is a perspective view of only the fixing spring. 4 to 6 show a second embodiment of the present invention, and FIG. 4 is a side view of a rotor for a small motor seen from the rotor pinion direction. FIG. 5 is a cross-sectional view of the main part taken along line B-B in FIG. FIG. 6 is a perspective view of only the fixing spring. FIG. 7 is a sectional view of main parts showing a third embodiment of the present invention. FIG. 8 is an explanatory diagram of a method of inserting a fixing spring into the rotor shaft. 1... Rotor for small motor, 10...
Rotor shaft, 14... Flange, 18, 19...
・・Flat area, 20・・・Ta-Yu magnet, 22・・・・
- Through hole of Ta-Yu magnet, 30, 40, 50...fixing spring, 36, 46, 48...fixing piece.

Claims (1)

[Scope of utility model registration request] a rotor shaft having a flange provided at one end in the axial direction, and a parallel flat portion formed by cutting out the shaft to include the flange;
A rotor magnet having a hole into which the rotor shaft can be inserted, a groove that can be attached to the flat part of the rotor shaft, a claw protrusion provided on the inner surface of the opening end of the groove, and an end bent in the rotor axial direction,
a fixed spring having a fixed piece that can engage with the outer peripheral surface of the rotor magnet, and the axial length of the flat part of the rotor shaft is equal to the combined axial thickness of the rotor magnet and the fixed spring. The rotor magnet is held between the flange of the rotor shaft and the fixed spring, and is fixed in the radial and axial directions by the contact surface with the fixed piece of the fixed spring. Characteristic rotor for small motors.