JPH04165943A - Metallic brush in plural rows of small-sized motor - Google Patents

Abstract

PURPOSE:To remove the dispersion of contact pressure so as to get stable contact by inclining the face of the top part, which includes the part in contact with, at least, a commutator of a branch part, to the base material face of a plate-shaped metallic brush. CONSTITUTION:1 is a brush base material, 4, a second clad material, and 5, a first layer clad material, and those constitute a brush. Each branch part is inclined by an angle theta to the base material face of the brush base material 1. Accordingly, it contacts with the commutator, in the vicinity of the edge 6. Since the brush contacts with the commutator, having an angle to the commutator, it becomes partial contact at the edge, and the contact pressure per unit area becomes large, and besides the spring constant per piece reduces to two- thirds, whereby electric contact stability can be gotten, and also abrased powder is discharged to outside from the space consisting of the contact angle of the brush, and the contact part can be kept clean.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a double-row metal brush for small motors used, for example, in tape recorders, video tape recorders, cameras, and the like.

BACKGROUND OF THE INVENTION FIG. 2 is a perspective view of a double-row brush whose tip portion, which contacts a commutator, is branched into a plurality of parts by slits.

1 is the brush base material, which is a thin plate of phosphor bronze.

2 is a relatively thin slit inserted from the tip, and 3 is a plurality of branched portions created by this slit 2.

Numerals 4 and 5 are precious metal crat materials fixed to the branch portion 3, and these portions come into contact with the commutator. The cladding material 4.5 is applied to the brush base material 1 by the pressure of clara 1~.
In reality, the metal plates are embedded in the metal plate, but for the sake of clarity, this figure shows the metal plates stacked on top of each other.

Conventionally, this double-row brush has a width of 0 or 0 at the branching part of the brush.
, about 3 mm, and the width of the slit was generally about 0.15 mm due to the capacity of the mass production process.

However, with brushes of the above dimensions, the splashing pressure at the branching part is relatively strong, and the contact between the brush and the commutator is unstable due to vibration of the brush contact surface during rotation due to minute eccentricity of the commutator, resulting in variations in motor rotational speed. There were drawbacks that had a major impact.

In addition, in order to prevent the brush from vibrating, it is common to have a structure in which anti-vibration rubber is attached to the brush, but this has the disadvantage that it cannot absorb vibrations.

For this reason, various measures have been taken to improve the contact stability between the commutator and brush of a small motor and to reduce fluctuations in rotational speed. For example, in order to improve the contact between the commutator and the brush, reduce wear, and reduce contact resistance, the brush sliding surface of the commutator can be cut with a diamond cutting tool to give it a mirror finish, or wrapping paper can be used to create a mirror surface of 1 μm or less. Measures have been taken such as finishing the surface to roughness, plating the commutator surface, and plating the commutator sliding surface of the brush with tin, platinum, or the like. However, none of these methods provide sufficient performance in terms of preventing fluctuations in rotational speed, or
In addition, they were unsatisfactory due to drawbacks such as high cost.

In addition, when assembling a product with a high spring constant on the contact surface with the brush, it is difficult to ideally control variations in contact pressure of the brush, resulting in abnormal wear and abnormal vibration due to variations in brush pressure. This had the disadvantage of causing performance deterioration.

Problems to be Solved by the Invention The present invention provides a brush that reduces variations in brush pressure at the contact surface with the commutator brush, stabilizes the contact between the brush and the commutator, and prevents performance degradation due to abnormal vibrations. The purpose is to provide.

Means for Solving the Problems In order to achieve the above object, the present invention makes the width of the branching portions of the brush 0.2 nnn or less, and also makes the slits between the branching portions thinner to increase the number of branching portions. The branch portion has an inclined shape at the contact portion with the commutator.

Effect: The above means reduces the spring constant per branch. However, since the brush hits the commutator obliquely, the contact pressure per unit area is high, so variations in contact pressure are reduced, and stable contact is achieved. Furthermore, as the number of branching portions increases, the probability that the brush of any branching portion will be in contact with the commutator increases significantly.

Embodiment FIG. 1 shows an embodiment of the present invention. The same members as those in FIG. 2 of the conventional example are given the same numbers, and explanations thereof will be omitted.

1 is the brush base material (phosphor bronze 0.09mm thick), 4 is the second brush material
Layer clad material (Ag92%, Cu6%.

2% Cd, 20 μm thick), 5 is the first layer cladding material (Au
75% Ag, 25% Ag, 6 μm thick>, and the brush is composed of these.

Each branch part has an angle θ with respect to the base material surface of the brush base material 1.
It's only slanted. This brush therefore comes into contact with the commutator in the vicinity of the edge 6.

The results of a practical test of the brush of the present invention for 2000 hours are shown in the following table.

O "1. Good, △ mark: Normal, × mark: Bad" According to the table, the width of the branch part of the brush is 0, 1
A diameter of 5 mm or more and 0.2 mm or less gives good results.
-6= Got it. By reducing the width of the branching part of the brush of the present invention, there are fewer fluctuations in motor rotational speed (less abnormal wear and less abnormal vibration). In other words, the brush contacts the commutator at an angle, resulting in uneven contact at the edges, which increases the contact pressure per unit area and increases the width of the branching part. Compared to a brush with a diameter of 0.3 mm, the apparent spring constant per brush is also reduced by 2/3, resulting in electrical contact stability, and wear particles are transferred to the outside through the gap formed by the contact angle of the brush. It is assumed that this is because the contact area can be kept clean by being discharged.

Effects of the Invention As is clear from the above explanation, according to the present invention, the following effects can be obtained.

1) The contact pressure per unit area of the brush increases, the electrical contact between the brush and the commutator becomes more stable, and uneven rotation of the small motor can be prevented.

2) There is no burnt wire between the brush and the commutator.
Abnormal wear and vibration of the brush and commutator can be prevented.

3) Longer life of small motors can be achieved due to the smooth contact of the brush commutator.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a double-row metal brush of the present invention, and FIG. 2 is a perspective view of a conventional double-row metal brush. ]...Brush base material (base material side), 2...
Slit, 3... Branch part, 4... Second layer cladding material, 5... First layer cladding material, 6
...Etsuji Department.

Claims (2)

[Claims] (1) The tip is divided into multiple branch parts by a slit made from the tip, and a plate-shaped metal brush that contacts the commutator at the branch part is used to separate at least the part of each branch that makes contact with the commutator. A small-sized motor double-row metal brush whose tip surface is oblique to the base material surface of the plate-shaped metal brush. (2) The double-row metal brush for a small motor according to claim 1, wherein the width of the branched portion is 0.15 mm or more and 0.2 mm or less.