JPS5918851Y2 - Rotor structure for converter - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a rotor structure for a small step motor or the like used in a converter for an electronic watch.

In recent years, rare earth intermetallic compound magnets have been used as magnet materials for converter rotors, but although they have a high energy product and have very good magnetic properties, they are hard and brittle. Fastening to the rotor pinion is extremely difficult and limited.

The currently adopted method connects the rotor pinion and the magnet through a seat made of a relatively large metal material to prevent the magnet from cracking or chipping, resulting in a complex structure and reduced assembly man-hours. Not only that, but the inertia rate of the rotor has also increased.

An increase in the inertia factor of the rotor impairs starting performance when the rotor is driven, making it necessary to lengthen the pulse width of the drive current, which has disadvantages such as shortening battery life.

On the other hand, synthetic resin is used to connect the rotor pinion and the magnet,
Although methods to reduce the inertia rate have been proposed, the problem is how to secure the fixing force with the rotor pinion.

Usually, when synthetic resin is used, a convex part or four parts are provided on the rotor pinion, and a fastening part made of synthetic resin is pushed into the convex part or concave part to ensure fixing force in the radial direction and thrust direction at the same location. However, converter rotors for electronic watches generally have rotor pinions with extremely small shaft diameters, so machining of convex or recessed parts for fastening is required for pinions with such shaft diameters. If this is done, processing distortion such as bending or warping of the rotor pinion will occur due to the stress during processing, making processing difficult and increasing the number of man-hours. In order to achieve this, it is necessary to increase the joint area between the rotor pinion and the fastening member, and for this reason, it is necessary to increase the shaft diameter of the rotor pinion, or to increase the shaft diameter of only the fastening part of the rotor pinion. An attached shaft structure is required, which increases the inertia factor of the rotor, resulting in a decrease in conversion efficiency.

The purpose of this invention is to eliminate the above-mentioned drawbacks, to provide a converter rotor that uses synthetic resin for fastening, reduces the inertia factor, is easy to process and assemble, and can secure sufficient fixing force to the rotor pinion. Our goal is to provide the following.

An embodiment of the present invention will be described below based on the drawings. In FIG. 1, 1 is a rotor pinion, and 3 is a rotor magnet 2 made of a rare earth intermetallic compound magnet, for example, SmCO5, which has already been fastened together by injection molding. The rotor seat is made of polymeric material.

Rotor seat 3 having rotor pinion 1 and rotor magnet 2
The connection is made by push-fitting the inner circumferential convex portion 3a of the rotor seat 3 with the tapered convex portion 1a formed on the shaft portion of the rotor pinion 1, and the toothed portion of the rotor pinion 1 on the end surface convex portion 3b of the rotor seat 3. This is done by interlocking by pushing into 1b.

However, in the above-mentioned fastening structure, immediately after fastening, the circumferential convex portion 3a
and a fastening portion formed by the tapered convex portion 1a, and the end surface convex portion 3b.
The two fastening parts, the fastening part by the toothed part 1b, both have a fixing force in the radial direction and the thrust direction between the rotor pinion 1 and the rotor seat 3, but the rotor seat 3
are made of a polymeric material, the material may creep due to changes over time after fastening and environmental changes mainly due to temperature and humidity, causing the inner peripheral convex portion 3a and end surface convex portion 3b to creep.
follows the shape of rotor kana 1.

As a result, the fixing force in the radial direction is lost at the fastening portion between the inner peripheral convex portion 3a and the tapered convex portion 1a due to a decrease in the pushing pressure due to creep, but due to the shape effect of the tapered convex portion 1a, the fixing force is lost in the vertical direction. Only the fixing force in the thrust direction is ensured by restricting the movement of , and the fixing force in the thrust direction is also lost due to creep at the fastening section between the end surface convex part 3b and the toothed part 1b. The rotor pinion 1 is secured only in the radial direction by restricting rotation due to the uneven shape of the teeth.
The fixing force in the thrust direction between the rotor seat 3 and the rotor seat 3 is ensured independently by the tapered convex portion 1a, and the fixing force in the radial direction is ensured independently by the toothed portion 1b.

Furthermore, the magnet holding inner peripheral portion 3C of the rotor seat 3 has a very small gap with the rotor pinion 1.

Therefore, when the rotor seat 3 is pressed into the rotor pinion 1, no force is applied to the rotor magnet 2 to spread it outward, so the rotor magnet 2 will not be broken, and the rotor seat 3 will be held in position by the magnet holding inner peripheral part 3C. To be judged,
The eccentricity of the rotor magnet 2 is kept very small.

FIG. 2 shows another embodiment, in which the shape of the end surface convex portion 3b of the rotor seat 3 is changed so that the fastening portion with the toothed portion 1b is performed only at the tooth tip.

Therefore, the fixing force in the radial direction hardly changes, but when the rotor seat 3 is pushed into the rotor pinion 1 and the rotor seat 3 is pressed and fastened, the end face 3d of the rotor seat 3 comes into contact with the pinion end face 1C. This prevents displacement in the thrust direction.

As described above, according to the present invention, by making the fastening part independent, the area of the fastening part can be substantially increased, so there are disadvantages such as an increase in the rate of inertia caused by increasing the shaft diameter. It is possible to secure fixing force without
In addition, by using the uneven shape of the teeth of the rotor pinion to perform radial fastening, there is no need for conventional complicated machining, resulting in a simple structure and easy processing and assembly. Since it can be made thinner except for the tooth-shaped part, the inner diameter of the rotor magnet can be made smaller, which has the effect of making it possible to use the magnet more effectively.
Since the rotor seat can be used, the positional accuracy of the rotor magnet is good, and the inertia factor can be reduced, an efficient converter can be realized and the life of the watch can be extended.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a rotor showing an embodiment of the present invention.
FIG. 2 is a sectional view of a rotor showing another embodiment. 1... Rotor pinion, 2... Rotor magnet, 3...
・Rotor seat.

Claims (1)

[Scope of utility model registration request] Hollowed out from polymer material, integrated rotor magnet, and
In a rotor structure in which a rotor seat having a fastening hole and a rotor pinion having a shaft portion and a toothed portion are integrated by pressing, a thrust direction fastening portion and a radial direction fastening portion between the rotor pinion and the rotor seat are provided. are provided independently, and the thrust direction fastening portion is constituted by a shaft portion of a rotor pinion and a fastening hole of a rotor seat that is press-fitted to the shaft portion, and the radial direction fastening portion is constituted by a toothed portion of a rotor pinion and a fastening hole of a rotor seat that is press-fitted to the shaft portion. A rotor structure for a converter, characterized by comprising a convex end surface of a rotor seat that bites into a toothed part.