JPS62196049A - Brush of small-sized dc motor - Google Patents

Abstract

PURPOSE:To reduce the electrical noise by folding down the brush from a given portion to its tip in the contacting direction with a commutator. CONSTITUTION:A brush 1 of a small-sized DC motor forms a folded portion 4a-4c by being folded at an angle theta in the direction towards a commutator 7 with a clad portion 3a-3c in its centre on the commutator contacting side of its divided brushes 2a-2c. A V-shaped folded portion 5a-5c is formed into which the brush is folded in V-shape so as to form the commutator 7 side of the folded portion 4a-4c into a projected portion. Thus, by the folded portion 4a-4c in the direction towards the commutator 7 and by the V-shaped folded portion 5a-5c the distance from the base of the brush 1 to the commutator 7 is so extended that the pursuability of the brush 1 can be improved. In this connection, it is desirable that the angle theta should be more than 10 deg. as the experiment will show.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a brush for a small DC motor that can be used in the mass production of small DC motors.

BACKGROUND OF THE INVENTION In recent years, the brushes of small DC motors have been developed as shown in Fig. 4.
The brush is divided into 2 to 4 parts near the side where it slides with the commutator, and is brought into contact with the commutator independently.The brush is also made of precious metal for the sliding part with the commutator to ensure stable contact. It is clad.

In FIG. 4, 1 is a brush, 2a, 2b, and 2c are divided brushes, and 3a+3b+3c is a cladding part.

Problems to be Solved by the Invention However, with the structure described above, brushes with a short distance from the base of the brush to the tip of the sliding part may not be able to slide easily due to variations in brush pressure, commutator roundness, and other processes. Since the characteristics are not stable, non-contact points are likely to occur. If this happens, a large frictional force will be generated between the commutator and the brushes, causing the problem of worsening electrical noise in the motor.

For this reason, in the past, the brushes were bent into a U-shape to increase the effective length or to make the brush thinner, but in the former case, in order to make the brush into a U-shape, the commutator and brush It was necessary to perform accurate positioning between the two, and it was difficult to increase the positioning accuracy.In the latter case, the thickness of the leaf spring was made thinner, which caused problems in terms of service life when operating for long periods of time. The problem was that it was difficult.

The present invention is intended to solve these conventional problems, and aims to stabilize sliding characteristics with a simple configuration and improve the occurrence of non-contact points and electrical noise.

Means for Solving the Problems In order to solve the above problems, the brush of the small DC motor of the present invention has an arbitrary shape based on the boundary line between the extension line from the base of the brush in the sliding direction and the cladding part. It has a structure in which the part from the part to the tip of the brush is bent by an angle θ in the direction of contact with the commutator, and both sides of the bent part of the brush that contact the commutator are bent into a V-shape to form a protrusion. be.

Function: The brush of the small DC motor of the present invention has a clad surface that contacts the commutator and is bent at an angle θ toward the commutator, and the clad portion is bent into a V-shape to form a protrusion. As a result, even in the case of a small DC motor where the distance from the base of the brush to the tip of the commutator contact part is short, the bent part of the cladding part formed on the brush prevents the brush from flying off due to commutator sliding. This reduces the occurrence of non-contact points and electrical noise.

EXAMPLE Hereinafter, a brush structure of a small DC motor according to an example of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the divided brushes 2a and 2 of the brush 1
Cladding q3a, 3b on the commutator contact side of b, 2c,
A bent part 4a bent at an angle θ in the direction of the commutator about 3c,
The bent portions 4b and 4c are bent into a V-shape so that the commutator side becomes a protrusion to form V-shaped bent portions 5a, 5b, and 5c. In this embodiment, there are three divided brushes, but the above structure may be formed regardless of the number of divided brushes.

In this way, the bent portion 4a is bent in the direction of the commutator.

4b + 4c and the V-shaped bent parts 5a, 5b, and 5c increase the distance from the base of the brush 1 to the commutator, and also improve the followability of the brush from the base of the brush 1 toward the commutator contact part. , can reduce brush flying.

Therefore, there is no need to complicate the shape of the brush, and the quality can be significantly improved. The second factor shows the relationship between the commutator and the brush, 6 is the anti-pregnancy rubber, and 7 is the commutator.

Note that the angle θ of the bent portions 4a, 4b, and 4c toward the commutator side is preferably 10 degrees or more based on experimental results.

FIG. 3 is a comparison of brush amplitudes between an embodiment and a conventional brush when the bending angle θ is 15 degrees during commutator rotation.

As shown in the figure, it is clear that the amplitude T of the brush is reduced according to the embodiment.

Note that the more acute the V-shaped bent portions 5a, 5b, and 5c are, the greater the effect is, which is desirable.

Effects of the Invention As described above, the brush of the small DC motor of the present invention has a brush that extends from any part to the tip of the brush, with reference to the boundary between the cladding and the line extending from the base of the brush in the direction of contact with the commutator. The brush is bent in the commutator contact direction, and the commutator contact surface side of the bent part of the brush is bent into a V-shaped shape that becomes a protrusion.The outer diameter of the motor is small and the commutator of the leaf spring is Even if the effective length to the child contact part is short, the brush bent at the center of the cladding part reduces non-contact points and electrical noise caused by brush flying when sliding with the commutator, so it is possible to use a small DC motor. It is highly effective in improving product quality, yield, and workability.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a brush of a small DC motor according to an embodiment of the present invention, FIG. 2 is a sectional view of essential parts of a small DC motor according to an embodiment of the invention, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a perspective view showing a brush of a conventional small direct current motor. 1...Brush, 2a, 2b, 2c...Divided brush, 3a, 3b, 3c...Clad part, 4a. 4b, 4c...Bending portion toward the commutator direction, 5a
+5 b. 5c...V-shaped bent part. Name of agent Patent attorney Toshio Nakao and 1 other person f-1, kid LTL, 2b, 2cm--divided SKfJI-fJa
Jb3cm--7, F4f= rrS1 Figure 2

Claims (1)

[Claims] In a brush made of a leaf spring whose sliding part with a commutator is clad with precious metal, the tip of the brush can be drawn from any part of the brush with reference to the boundary line between the extension line from the base of the brush in the sliding direction and the cladding part. up to the commutator contact direction by an angle θ,
A brush for a small DC motor, in which both sides of the bent portion of the brush that contact the commutator are bent into a V-shape to form a protrusion.