JP3549279B2 - Commutator motor - Google Patents

Description

[0001]
[Industrial applications]
TECHNICAL FIELD The present invention relates to a commutator motor used for a household vacuum cleaner, a power tool, and the like.
[0002]
[Prior art]
In recent years, commutator motors used for household cleaners, electric tools, and the like have been particularly miniaturized and increased in capacity, and accordingly, carbon brushes (hereinafter referred to as brushes) have also been miniaturized. However, although the resistance loss is small and the wear is small, the demand is increasing.
[0003]
Conventionally, brushes for AC commutator motors use a material with a high conductivity, which reduces resistance loss but increases the risk of sparks and abrasion. Then, sparks are less likely to occur and wear is reduced, but resistance loss increases and the temperature rises due to heat generation, and copper powder and lead copper wire used for the compression and joining parts where the lead copper wire is connected to the brush However, there is a problem that the electrical conductivity deteriorates due to oxidation, and finally the motor stops, and there is a problem that it is difficult to cope with these problems.
[0004]
Also, among brushes for AC commutator motors, motors that rotate at high speeds, such as those for vacuum cleaners, have good commutation even at high speeds and need to be replaced during the usable period of the vacuum cleaner body. Because of the required characteristics of extending the life of the brush so as not to cause a problem, a resin-bonded brush obtained by bonding graphite powder with a resin binder and hardening may be used. However, the resin-bonded brush has a problem that the conductivity of the brush body is small, so that when the current density is increased, the temperature rises and the resin used for the binder is deteriorated.
[0005]
As a known example for solving these problems, Japanese Patent Application Laid-Open No. 5-182733 proposes a brush in which an electrically conductive metal coating is applied to the entire surface of a brush substrate except for a commutator sliding surface of the brush. ing.
[0006]
[Problems to be solved by the invention]
However, in the brush described in Japanese Patent Application Laid-Open No. 5-182733, since the electrically conductive metal coating is applied to the entire surface of the brush substrate except for the commutator sliding surface, the electrically conductive metal coating is applied. Some surfaces have low resistance and can reduce resistance loss.However, the rear surface in the sliding direction of the brush that slides on the commutator, that is, the side surface that generates sparks during sliding, also has low resistance. Therefore, there is a problem that the current also concentrates on this side surface, the spark becomes large, the characteristics become unstable, and the variation of the brush life becomes large.
[0007]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a commutator motor that solves the above-mentioned problems of the prior art and has a small resistance loss of the brush, a long brush life, and a small variation in the brush life.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the commutator motor according to the present invention is provided with a jacket having better electrical conductivity than the brush base material on the side peripheral surface of the brush base material except for the side surface on the commutator outlet side of the brush. It is characterized by wearing a carbon brush.
[0009]
In order to solve the above-mentioned problems, the commutator motor of the present invention is preferably provided with a brush having good electrical conductivity also on the brush end face opposite to the commutator sliding face of the brush. is there.
[0010]
[Action]
The commutator motor according to the present invention is provided with a carbon brush having a more electrically conductive jacket than the brush base material on the side peripheral surface of the brush base material except for the side surface of the brush at the commutator outlet side . Therefore, the electric conductivity of the outer peripheral surface of the brush on the side of the brush lowers the resistance of the brush, thereby reducing the resistance loss of the brush. The resistance is higher than that of the side part, the current density in that part is small, the spark generation in that part can be reduced, the characteristic fluctuation of the commutator motor is reduced, and the brush life is extended. In addition, variations in brush life are reduced.
[0011]
Also, if the brush end surface on the opposite side of the brush commutator sliding surface is also provided with an electric conductive covering, a pigtail is attached to this surface, so that the pigtail directly lowers the resistance. As a result, the resistance loss of the brush can be further reduced.
[0012]
【Example】
One embodiment of the present invention will be described with reference to FIGS.
[0013]
FIG. 1 is a perspective view showing a method of applying an electric conductive jacket to a brush used in a commutator motor according to the present invention, and FIG. 2 shows a mounting direction of a brush used in a commutator motor according to the present invention. FIG.
[0014]
In FIG. 1, a brush 1 is made of a carbon brush base material such as artificial graphite, and has a good electrical conductivity between a commutator sliding surface 1c and a rear side in the sliding direction (commutator outlet side of the brush) 1b. The other three side surfaces 1u, 1f, 1d are covered with an electrically conductive outer cover 6, and a pigtail 1a is attached to a brush end surface 1r opposite to the commutator sliding surface 1c. In this embodiment, the electric conductive jacket 6 is applied to the carbon brush base material by plating. As described above, in order to prevent the outer side surface 1b in the sliding direction from being provided with a jacket having good electrical conductivity, there are a method of masking when plating and a method of removing after plating over the entire surface. Of course, the method of forming the outer layer 6 having good electrical conductivity is not limited to plating, and various thin film forming techniques can be used.
[0015]
In FIG. 2, a deformed tube 2 made of a conductive material encloses a brush 1 and welds the tip of a pigtail 1a to itself. The brush spring 3 is attached by a helical spring so that the pigtail 1a passes through the helical space. Both ends of the brush spring 3 abut on the brush 1 and the deformed pipe 2, so that the brush 1 is pushed out of the deformed pipe 2. I have. The pigtail 1a is a bundle obtained by knitting a thin copper wire or the like, is flexible, has a sufficient length as shown in FIG. 2, and is initially slack. The brush 1 is pushed out of the deformed pipe 2 by the force of the brush spring 3 with the wear of the brush 1 until the length of the brush 1 becomes insufficient, so that the brush 1 can be used continuously. Reference numeral 4 denotes a retainer for holding the deformed tube 2, reference numeral 5 denotes a commutator, and solid arrows indicate the rotation direction of the commutator 5.
[0016]
In the commutator motor of the present invention, as shown in FIG. 2, the rear side surface 1b in the sliding direction of the brush 1 that slides on the commutator 5 in the direction indicated by the dotted line is a surface without the electric conductive jacket 6. Is attached to the commutator motor. In this way, the electrically conductive outer cover 6 applied to the three peripheral surfaces 1u, 1f, and 1d of the brush 1 reduces the resistance of the portion, thereby reducing the resistance loss of the brush 1, and The rear surface 1b in the sliding direction of the brush 1 has a higher resistance than the three side surfaces 1u, 1f, and 1d, and the current density in that portion is reduced, so that spark generation in that portion can be suppressed. In addition, fluctuations in the characteristics of the commutator motor are reduced, the brush life is extended, and the variation in the brush life is reduced. In this case, if the end surface 1r of the brush base material opposite to the commutator sliding surface 1c is also provided with an outer casing 6 having good electrical conductivity, the pigtail 1a is attached to this surface. 1a comes into direct contact with the low resistance portion, and the resistance loss can be further reduced.
[0017]
【The invention's effect】
Since the commutator motor of the present invention has a carbon brush on which the outer periphery of the brush substrate is provided with a better electric conductivity than the brush substrate, except for the side surface on the commutator outlet side of the brush, the resistance loss is reduced. And the brush life is long, and the variation in the brush life is reduced.
[0018]
Further, in the commutator motor of the present invention, when a brush having good electrical conductivity is applied to the brush end surface opposite to the commutator sliding surface of the brush, a pigtail is attached to this surface. This has the effect of further reducing the resistance loss.
[Brief description of the drawings]
FIG. 1 is a perspective view showing how a brush used in a commutator motor according to the present invention is provided with an electrically conductive jacket.
FIG. 2 is a perspective view showing a mounting direction of a brush used in the commutator motor of the present invention with respect to a rotation direction of the commutator.
[Explanation of symbols]
1 Carbon brush 1a Pigtail 1b Rear surface in sliding direction (commutator outlet side of brush)
1c Commutator sliding surface 5 Commutator 6 Electric conductive jacket

Claims (2)

A commutator motor characterized in that a carbon brush provided with a jacket having better electric conductivity than the brush base material is attached to a side peripheral surface of the brush base material except for a side surface on a commutator outlet side of the brush. The commutator motor according to claim 1, wherein the brush end face opposite to the commutator sliding face of the brush is also provided with a jacket having good electrical conductivity.

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