JP3280237B2 - Brush device for small DC motor and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brush device for a small DC motor and a method for manufacturing the brush device, which are suitable for use as a silent notification means of a portable radio communication device, and more particularly, has an opening angle of less than 180 degrees for sliding contact with a commutator. The present invention relates to a device in which the opening angle for sliding contact with the commutator is constant even when the amount of deflection is large.

[0002]

2. Description of the Related Art Conventionally, a brush device of a small DC motor in which a pair of plate brushes is implanted through a terminal on a brush base made of a synthetic resin or an electrode pattern of a brush base made of a printed wiring board is widely used. Is known to. In addition, a small DC motor used for a silent sound notification unit of a portable wireless communication device is required to have low current consumption, and a conventional three-segment commutator, a two-pole field,
6-segment, 4-pole field, 90
Degree opening angle brush structure or 12 segments,
An 8-pole field, 45 (135) degree open angle brush structure is often used. Such a small DC motor brush device having a sliding contact opening angle of less than 180 degrees is, for example, an actual open flat 7-32.
As shown in FIG. 9 of No. 80, it is often formed in a symmetrical shape when viewed from a plane.

[0003]

However, a brush device formed in a symmetrical shape when viewed from the plane of such a small DC motor having a sliding contact opening angle of less than 180 degrees has a distribution area diameter of 6 mm.
When ultra-miniature size of less than millimeter is required, there is a problem that the amount of deflection cannot be increased by the ordinary simple arrangement structure, and when trying to forcibly increase the amount of deflection, the base of a pair of brushes is Since it is formed in one direction and symmetrically to the left and right as viewed from the plane, the sliding contact opening angle when actually sliding on the commutator does not reach a predetermined value, and there is a problem in rectification characteristics. Such a brush device is obtained by disposing a brush spotted on a terminal to a brush base by means such as press-fitting or by soldering a base of the brush to an electrode pattern of a brush base formed of a printed wiring board. However, since each part is small, workability is extremely poor, which is extremely difficult. In addition, if the brushes are individually connected, it is difficult to determine the positions where the brushes are to be arranged, and the condition for sliding contact with the commutator is not constant, which involves quality problems.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sliding contact in which the direction of movement of the sliding contact opening angle due to deflection when sliding on a commutator is the same, even if the diameter of the distribution area is extremely small. Even when the opening angle is made constant and the amount of deflection is increased, high quality is achieved by eliminating the variation in the sliding contact angle during the sliding contact of the commutator. Another object of the present invention is to provide a brush device and a brush device capable of ignoring the workability problem in disposing a brush on a microminiaturized brush base, that is, capable of easily performing automatic assembly and reducing costs. It is intended to provide a manufacturing method.

[0005]

The object of the present invention is to form a pair of brushes so that the right and left sides are asymmetrical when viewed from a plane, and to effectively use a dead space in a distribution area to increase the amount of deflection. The problem can be solved by taking a means of cutting after connecting the connected ones according to the pitch of the brush base. With this configuration, even when the amount of deflection is increased, the sliding contact opening angle at the time of sliding contact with the commutator can be set to a predetermined value, so that automatic assembly can be performed and cost reduction can be achieved.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention include:
According to a first aspect of the present invention, there is provided a brush device for a small DC motor having a pair of brushes having a base portion implanted in a brush base and slidingly contacting a commutator at an opening angle of less than 180 degrees. What is necessary is just to make it the asymmetrical shape when seen from a plane and to make the other brush go around the sliding contact part of one brush. By doing so, the direction of the displacement of the sliding contact opening angle due to the deflection when the sliding contact is made with the commutator becomes constant, and a predetermined sliding contact opening angle is obtained. As a result, the overall length of the brush can be increased and the amount of deflection can be increased, so that a sliding contact pressure with less variation can be obtained. Embodiments of the present invention having a sliding contact angle of less than 180 degrees include 90 degrees or 135 degrees (90 degrees).
(3 times 45 degrees, half the degree). In this case, the number of effective conductors contributing to torque generation increases according to the number of poles of the field to be combined, and the efficiency is improved. Further, it is preferable to provide a means for correcting the sliding contact pressure of a pair of brushes, such as making the other brush wider than the one brush, or partially providing a narrow portion on the inner brush. By doing so, the sliding contact pressure of the pair of brushes can be made equal. Embodiments of the manufacturing method of the present invention include: A step of forming a plurality of pairs of brushes at a predetermined pitch so as to be asymmetric when viewed from a plane and configured so that the other brush goes around the sliding contact portion of one brush. 2. A step of distributing the base of the brush to a brush base having a brush disposition portion formed in accordance with the pitch. 3. A step of separating each connecting portion of the brush. Can be achieved. By doing so, the relative position of the brush and the brush base will be constant,
When the sliding contact angle when sliding on the commutator is constant, automatic assembly can be performed.

[0007]

FIG. 1 is a plan view of a main part of a first embodiment of the present invention. That is, 1 is a pair of terminals formed integrally with the brush base 2 connected and formed, and the bases a and b of the flat brushes 3 and 4 are spot-welded. The sliding contact portions c and d of the flat brushes 3 and 4 are formed in a bowl shape when viewed from the side, and are set so as to obtain a sliding contact opening angle of 90 degrees. The other brush 4 is configured to wrap around the outside, and is formed asymmetrically when viewed from a plane. In this case, by making the other brush 4 slightly wider than the one brush 3, it is preferable to make the sliding contact pressure of the pair of brushes equal. Of course, a narrow portion may be provided partially on one brush 3. Such a brush device forms a pair of continuous terminals 1 by press-forming a band-shaped tin plate or the like at a predetermined pitch as shown by an imaginary line, and fits them into a mold formed at the same pitch. The brush base 2 formed by injection molding with polyphenylene sulfide or the like is continuously integrated so as to expose a portion where the bases of the flat brushes 3 and 4 are spotted. A pair of continuous flat brushes 3 and 4 press-formed at the bases a and b are spot-welded to the terminal at their bases a and b, and the connecting portions 1a and 3a are cut along a cutting line S1,
It is manufactured by cutting at S2.

FIG. 2 is a cross-sectional view taken along the brush spot welding portion of FIG. 1 and shows a recess 2 in which a spot electrode can be inserted below the brush spot welding portion of the brush base 2.
a is provided. By doing so, the bases a and b of the brushes 3 and 4 can be easily spot-welded even in a terminal integrally molded with the brush base 2. In the figure, reference numeral 5 denotes a case indicated by an imaginary line. In this case, the brush base 2 is fixed to a metal bracket 6. The brush base 2 may be formed integrally with the metal bracket 6 to separate them. Further, reference numeral 7 denotes a magnet.

FIG. 3 is a plan view of a main part of a second embodiment of the present invention, in which the brush base 22 is formed of a flexible printed wiring board unlike the first embodiment.
That is, the bases a and b of the flat brushes 3 and 4 are solder-connected to the brush base 22 on the electrode pattern 22.
a and 22b are formed and connected at the same pitch as the flat brushes 3 and 4, and the bases a and b of the flat brushes 3 and 4 are cut by soldering and then cut holes S and S.
, One by one, and fixed to the metal bracket 6 as described above via a glue (not shown) on the back surface. Of course, the metal brackets 6 may also be formed at the same pitch, fixed to all, and then separated individually.

FIG. 4 is a plan view of a main part of a third embodiment of the present invention. The first and second embodiments have been described with reference to an axial sliding contact type flat brush, but the diameter is smaller. It is a directional sliding contact type. That is, in the same figure, the pair of radial brushes 33 and 44 are arranged so that the sliding contact portions cc and dd where noble metal foils are clad inside each other can obtain a sliding contact opening angle of 90 degrees. The other brush 44 is configured to go around the outside of the sliding portion cc of the one brush 33, and is similarly formed asymmetrically when viewed from a plane. A pair of plate brushes 3 thus configured
The base portions aa and bb of the bases 3 and 44 are bent and made flat, and are spot-welded to the pair of continuous terminals 1 and 1 as described above. Further, it is the same as that of the first embodiment described above in that it is manufactured by separating the connecting portions 1a and 3a therefrom at the cutting lines S1 and S2.

In each of the above embodiments, the brush has a sliding contact opening angle of 90 degrees. However, another sliding contact opening angle of less than 180 degrees, for example, 135 times three times the above 45 degrees is used.
It may be a degree. The principle of rotation and the like of the sliding contact angle of 135 degrees is disclosed by the present applicant in Japanese Patent Application No. Hei 7-26483.
This is described in detail in No. 1 and is not the gist of the present invention, so that the description is omitted here. In addition, the method of manufacturing a brush device for a small DC motor according to the present invention is, in summary, configured so that the brush is asymmetric when viewed from a plane, and the other brush goes around the sliding contact portion of one brush. a pair of brushes plurality ligated formed at a predetermined pitch, and Haigi the base of the brush in the brush base to form a brush Haigi portion in accordance with the above pitch, then, the brush and Bed
The brush base assembly is completed by separating the connecting portions of the brush base.

[0012]

As described above, the brush device for a small DC motor according to the present invention is configured such that a pair of brushes is asymmetrical as viewed from a plane, and the other brush goes around the sliding contact portion of one brush. Accordingly, the displacement of the sliding contact opening angle due to the deflection when the sliding contact is made with the commutator is in the same direction, and a predetermined sliding contact opening angle is obtained. As a result, the overall length of the brush can be increased and the amount of deflection can be increased, so that a sliding contact pressure with less variation can be obtained. Further, the sliding pressure of the pair of brushes can be made equal by taking the means for correcting the sliding pressure of the pair of brushes.

According to the method of manufacturing a brush device for a small DC motor of the present invention, as described above, a pair of brushes are constructed so as to be asymmetrical when viewed from a plane and so that the other brush goes around the sliding contact portion of one brush. Is formed by connecting a plurality of brushes at a predetermined pitch, disposing the base of the brush on a brush base on which a brush dispensing portion is formed in accordance with the pitch, and then disconnecting each connecting portion of the brush. The base can be easily assembled, and even though it is extremely small, automatic assembly can be easily performed. In addition, since the brush is connected to the brush base for distribution, the positional relationship between the brush and the brush base does not vary. Therefore, it is possible to make the position of the brush concentric with the shaft, and the reliability at the time of sliding contact with the commutator is improved.

[Brief description of the drawings]

FIG. 1 is a plan view of a main part of a first embodiment of a brush device for a small DC motor according to the present invention.

FIG. 2 is a cross-sectional view of a main part, which is cut by a brush attachment part in FIG. 1;

FIG. 3 is a plan view of a main part of a second embodiment of the apparatus of the present invention.

FIG. 4 is a plan view of a main part of a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Terminal 1a Terminal connection part 2 Brush base 2a recess 3, 4 Flat plate brush a, b Base c, d Sliding contact part 3a Brush connection part S1 Terminal cutting line S2 Brush cutting line 5 Case 6 Metal bracket 22 Flexible Brush bases 22a, 22b formed of printed wiring boards Electrode patterns 33, 44 Board brushes aa, bb Base

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02K 13/00-13/14 H01R 39/18 H01R 39/24

Claims (5)

(57) [Claims] 1. A brush of a small DC motor having a pair of brushes (3, 4, 33, 44) having a base mounted on a brush base (3) and slidably contacting the commutator at an opening angle of less than 180 degrees. In the apparatus, a pair of brushes is made asymmetrical as viewed from a plane, and one of the brushes (3, 3).
3) A brush device for a small DC motor, wherein the other brush (4, 44) goes around the outside of the sliding contact portion of (3) . 2. The brush device for a small DC motor according to claim 1, wherein the sliding contact opening angle is 90 degrees. 3. The brush device for a small DC motor according to claim 1, wherein the sliding contact opening angle is 135 degrees. 4. A brush device for a small DC motor according to claim 1, further comprising means for correcting a sliding contact pressure of a pair of brushes. 5. A method of manufacturing a brush device for a small DC motor, comprising the following steps: Make it asymmetrical when viewed from a plane and one brush
The outside of the sliding portion of (3, 33) is brushed with the other brush (4, 4).
4) a step of connecting and forming a plurality of brushes at a predetermined pitch, wherein a plurality of brushes are arranged so as to wrap around; A plurality of brushes are connected to terminals (1) of a brush base (2) having a brush disposition portion formed in accordance with the pitch.
2. distributing the base of the brush with; Thereafter, the brush and the connecting portion of the brush base (3a, 1a) to cut away to brush base assembly
Completed as a process.