JPH0214312Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(Industrial Application Field) The present invention applies to brushes of small motors, especially commutators whose wide tips are bent into a V-shape and are coated with lubricant. A brush for a small motor equipped with a sliding brush sliding part, in which a cut-and-raised piece is provided on the protrusion to stabilize the state of contact with the commutator. It is. (Problems to be solved by conventional techniques and ideas) Generally, a commutator of a motor is coated with a lubricating oil (hereinafter referred to as commutate oil) such as grease. Therefore, in order to improve the electrical contact between the commutator and the brush, the brush of a conventional small motor has a brush sliding part 1 that slides with the commutator, as shown in FIG.
is bent into a V-shape so that the top part (referred to as a protrusion 1' in this specification for simplicity) forming the bent ridge line of the V-shape slides with the commutator 5 as shown in FIG. 3D. By doing so, it is considered that the above-mentioned commutator oil can be removed easily and the brush can come into good contact with the commutator 5. 3A is a side view, FIG. 3B is a plan view, FIG. 3C is a sectional view taken along arrow A-A in FIG. 3B, and FIG. 3D is an explanatory diagram of the state of contact between the brush and the commutator. In the figure, numeral 2 represents a brush arm portion, 3 represents a brush base, and 4 represents a terminal portion. In order to improve the removal of the rice oil, it is desirable that the protrusion 1' on the brush sliding part 1 be made as acute as possible.
Since the brush sliding portion 1 is bent to form the projection 1', it is inevitable that a curved surface will be formed to some extent. Therefore, it is difficult to completely remove the commutator oil, so unless the pressing force (brush pressure) on the commutator 5 is relatively strong, the contact state will not be stable, and as shown in FIG. 2B. As will be described later, there is an undesirable problem in that the fluctuation in rotational speed becomes large. Increasing the brush pressure too much may not only cause problems with the structure of the brush, but also increase the friction between the brush and the commutator, raise the natural frequency of the brush to an undesirable level, and even cause damage to the machine. This includes problems such as causing poor physical and electrical contact. (Means for Solving the Problems) The purpose of the present invention is to solve the above-mentioned problems. Therefore, the brushes of the small motor of the present invention are formed of a conductive metal plate and have a wide tip. The brush for a small motor is provided with a brush sliding part whose portion is bent into a V-shape and the top of the V-shape slides on the commutator, and the top of the brush slides on the commutator coated with lubricant. It is characterized in that a cut-and-raised piece is provided at the top of the V-shape of the brush sliding part, and the tip of the cut-and-raised piece is formed so as to come into contact with and slide on the commutator. (Embodiment of the invention) Fig. 1 is an explanatory diagram for explaining an embodiment of the brush according to the invention, Fig. 1A is an explanatory diagram of the manufacturing process of the brush sliding part, and Fig. 1B is an explanatory diagram of the brush sliding part. A perspective view of the sliding part, FIG. 1C is indicated by the arrow B-B in FIG. 1B.
FIG. 1D shows an overall plan view. In addition, Fig. 2 shows the experimental results for explaining the characteristics regarding the fluctuation of the rotation speed of a small motor using a brush related to the present invention, Fig. 2 A relates to the present invention, and Fig. 2 B shows a conventional example. It is related to. The manufacturing process of the brush sliding part 1 in the brush of the present invention will be explained with reference to FIG. 1A. First, by punching, such as pressing,
Conductive metal plate (e.g. copper-beryllium alloy plate)
As shown in Figure 1A, the wide brush sliding parts 1, 1
and the brush arm portion 2 are integrally formed. Then, a cut is made to form a cut-and-raised piece 6 whose tip is located at a distance a distance shown from the center line (arrow 1' in the drawing) of the brush sliding parts 1, 1, and then the above-mentioned Fold at center line 1'. A perspective view of the brush sliding portion 1 after the bending process is shown in FIG. 1B, and a cross-sectional view taken along arrow B-B in FIG. 1B is shown in FIG. 1C. That is, the brush sliding portion 1 is formed with a cut-and-raised piece 6 having a sharp tip.
Note that the above dimension a is approximately 0.05 to 0.10 mm, and the gap dimension (dimension b shown in Figure 1C) caused by the formation of the cut and raised piece 6 is 0.03 to 0.20 mm.
It is desirable to keep the amount within a certain range. An overall plan view of the brush of the present invention having the brush sliding part 1 manufactured in this manner is shown in FIG. 1D. Although the brush is not shown, as is generally well known, it is supported at the brush base 3 by a small case of a small motor.
The terminal portion 4 is pulled out to the outside of the motor.
Further, the brush sliding portion 1 and the commutator 5 come into contact as shown in FIG. 3D. That is, in the present invention, the portion that contacts the commutator 5 is the tip of the cut and raised piece 6. Therefore, the commutator oil applied to the commutator 5 is better removed and the contact condition is stable, so the small motor using the brush of the present invention is superior to the conventional small motor described at the beginning of this specification. It has the following excellent features: Brush pressure can be reduced. There is no problem even if there is some variation in the bending angle of the brush sliding part 1. There is no problem with slight variations in the amount of komi oil applied. As is clear from the experimental results shown in FIG. 2, the rotational speed variation characteristics are good. That is, the variation in the rotational speed of the motor when the motor is continuously operated is small at least at the initial stage of operation. Furthermore, the rotation speed characteristic showing the change in rotation speed during continuous operation of the small motor according to the present invention is shown in FIG. 2A, and the rotation speed characteristic of the small motor according to the conventional example is shown in FIG. 2B. Illustrated in. Note that a, b, and c in the figure show the rotational speed of three small motors of the same type over time. Furthermore, the elongated hole 7 in the embodiment shown in FIG.
It is punched out along the center line of the brush arm section 2. By forming the elongated hole 7, the brush arm portion 2 is also substantially bent during the above-mentioned bending process of the brush sliding portion 1, so that the brush arm portion 2 is reinforced. That will happen. As shown in FIG. 3D, there is contact resistance between the commutator 5 and the sliding brush sliding part 1, and due to this contact resistance, the brush arm part 2 is As a result, an expansion tension force that pulls the arm portion in the longitudinal direction or a compression force that compresses the arm portion in the longitudinal direction acts. That is, in the embodiment shown in FIG. 3D,
There is no problem if the tension is applied when the rotation direction of the motor is clockwise as shown in the figure, but if the motor rotates counterclockwise, the brush arm 2
Since the compressive force acts on the brush arm portion 2, the brush arm portion 2 curves or stretches, and the state of contact with the commutator 5 becomes unstable.
The mechanical strength of the material is an issue. In the conventional example (shown in Figure 3) described at the beginning of this specification, only the brush sliding part 1 is bent, and the brush arm part 2 is flat, so that during the counterclockwise rotation described above, Not only is it weak against compressive force, but it is also susceptible to twisting. As a result, the contact state with the commutator becomes unstable, resulting in large rotational fluctuations in the motor, and electrical sparks are generated, which accelerates wear on the commutator and brush sliding parts, shortening the motor's lifespan. It contained. The brush shown as an embodiment of the present invention, as described above, has an elongated hole in the brush arm to strengthen the brush arm and solve the drawbacks of the conventional brush arm. In addition, the experimental results conducted by the inventors of this application (Tables 1 and 2 below)
It is clear from Table 1 that the small motor using brushes shown as an embodiment of the present invention is far superior to conventional motors in terms of motor life and degree of wear. Table 1 shows the average values for motors whose rotational direction is counterclockwise and whose life has come to an end due to some reason, and Table 2 shows the average values for motors whose rotational direction is counterclockwise. The figure shows the average value of damage to the brush arm due to the compressive force acting in the counterclockwise direction. Further, A indicates the motor life time, and B and C indicate the amount of wear of the commutator and brushes.
In addition, in the case of a motor as shown in FIG. 3D, when the rotation direction of the motor is clockwise, a tension force is applied to the brush arm 2, so in the experiment, the rotation direction was counterclockwise. only was selected.

【table】

[Table] As explained above, in the present invention, the brush sliding part is electrically contacted with the commutator by the sharp corner (the tip of the cut and raised piece 6 in the present invention), so that the commutator oil can be removed. However, as a means for merely bringing the sharp corner into contact with the commutator, a means as shown in FIG. 4 may be considered. That is, by providing a long hole as indicated by the arrow d in FIG. 4A along the center line of the brush sliding portion 1 and then bending it in the same manner as in the embodiment shown in FIG. 1, the perspective view shown in FIG. 4B is obtained. Brush sliding part 1 like
can be formed. This is thought to be desirable because the corner around the elongated hole d in the brush sliding portion 1 comes into contact with the commutator, but when the wear of the corner progresses, the arrow e shown in the figure
comes into contact with the commutator, so the fourth
The illustrated examples are not necessarily preferable. (Effects of the Invention) As explained above, according to the present invention, the contact state between the brush and the commutator is stabilized, and the compact size makes it possible to improve the rotational fluctuation characteristics of the motor and significantly extend the life of the motor. Motor brushes can be provided.

[Brief explanation of the drawing]

1A to 1D are explanatory diagrams for explaining an embodiment of the brush according to the present invention, and FIG. 2A is a rotational fluctuation characteristic of a small motor using the brush of the present invention.
Figure 2B is the rotational fluctuation characteristic of a small motor using a conventional brush, Figures 3A to D are explanatory diagrams for explaining the conventional brush, and Figures 4A and B are explanatory diagrams for explaining the mode of the brush. Show the diagram. In the figure, 1 is a brush sliding part, 2 is a brush arm part, 3 is a brush base, 4 is a terminal part, 5 is a commutator, 6 is a cut and raised piece, and 7 is a long hole.

Claims (1)

[Scope of utility model registration request] The brush is formed of a conductive metal plate, and its wide tip is bent into a V-shape, and the top of the V-shape is provided with a brush sliding part that slides on a commutator, and the top is coated with a lubricant. In the brush of a small motor that slides on the commutator, a cut-and-raised piece is provided at the top of the V-shape of the brush sliding part, and the tip of the cut-and-raised piece is formed so as to come into contact with and slide on the commutator. A small motor brush that is characterized by: