JP2001298913A - Brush - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a brush wherein both voltage drop restraint and frictional force reduction are achieved and excellent commutation is realized. SOLUTION: In this brush (1), graphite particles (11) whose grain diameter is <=30 μm and copper particles (12) whose grain diameter is <=30 μm are mixed by using cementing solvent, and the mixture is backed. Since the cementing material is used, charges charged on fine particles are discharged in the cementing solvent, two particles are easy to be uniformed. The brush which is mixed and uniformed is baked, so that the cementing solvent is eliminated and not turned into resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brush used for a small motor for an automobile.

[0002]

2. Description of the Related Art Conventionally, it has been known that in a rectifying portion brush used for a small motor vehicle, a voltage drop occurs at a contact portion between the brush and the commutator due to an increase in resistance value. This voltage drop is caused by the oxide film generated on the surface of the copper particles, which are the components of the brush.To remove this voltage drop, the copper oxide film, which is the resistor, is partially peeled off, and the copper is turned on. Need to be sure. Here, as a method of removing the copper oxide film, there are a method of increasing the brush pressure on the commutator and separating with a large frictional force, and a method of increasing the copper content to increase the friction coefficient of the brush body and the like. . However, in either case, the frictional force between the brush main body and the commutator is increased to separate the brush main body and the commutator. Therefore, the brush main body vibrates due to the unstable contact due to the frictional force, leading to unstable commutation. Therefore, there is a limit to the need to reduce both the frictional force of the brush and the voltage drop.

[0003] In order to solve the above-mentioned problem, for example, Japanese Patent Application No. 11-359693 discloses a method for easily peeling off a copper oxide film.
As described in the above publication, a brush obtained by previously forming fine particles of copper to 30 μm or less, collecting the fine particles, and compressing and forming the fine particles is considered. However, in this method, when mixing the fine particles of copper and graphite, the fine particles are charged, the fluidity of the fine particles is poor, the copper particles and the graphite particles are difficult to be uniform, and a non-uniform brush is produced. There was a problem. In addition, it was necessary to find the ratio of copper particles and graphite particles that improved the opposing performances of slidability with a commutator (mechanical frictional force) and voltage supply (voltage drop suppressing force).

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and in order to realize good rectification, the fine particles of copper and graphite are made uniform, and the slidability and voltage supply amount are reduced. Both aim to obtain excellent brushes.

[0005]

According to a first aspect of the present invention, there is provided a brush for contacting a commutator and supplying power to a motor, comprising a graphite particle having a particle size of 30 μm or less and a brush having a particle size of 30 μm or less.
A brush which is uniformly mixed using a bonding solvent for bonding copper particles having a size of not more than μm, and which is baked so as to eliminate the bonding solvent.

[0006] To achieve the above object, a second invention provides
A brush that contacts the commutator and feeds power to the motor. The brush is uniformly mixed with a joining solvent that joins graphite particles having a particle size of 30 μm or less and copper particles having a particle size of 30 μm or less, and the mixture is dried. A brush in which the dried mixture is pulverized into aggregated particles having a particle size of 100 μm or more, the aggregated particles are compression-molded into a brush shape, and the compression-formed product is fired to eliminate the bonding solvent.

[0007] To achieve the above object, a third invention provides
A brush that contacts the commutator and feeds power to the motor. The brush is uniformly mixed with a joining solvent that joins graphite particles having a particle size of 30 μm or less and copper particles having a particle size of 30 μm or less, and the mixture is dried. The dried mixture is pulverized into aggregated particles having a particle diameter of 100 μm or more, and the aggregated particles are compression-molded into a brush shape while inserting one end of a pigtail for supplying power to the brush body. A brush that has been fired and the fired material has been cut.

[0008] In order to achieve the above object, a fourth invention provides:
The brush according to claim 1, wherein the bonding solvent uses a paraffinic hydrocarbon solvent.

[0009] To achieve the above object, a fifth invention provides
The brush according to claim 1, wherein the weight percentage of the copper particles with respect to the brush is 50 to 90%.

According to the first aspect of the present invention, the smaller the particle size of the copper particles used for the brush, the thinner the oxide film and the smaller the specific resistance which is the voltage supply amount, and the smaller the particle size of the graphite particles, the smaller the particle size. The frictional reduction, which is the slidability, is improved, resulting in an excellent brush. Here, as shown in FIG. 6, the time A for uniformly mixing the graphite particles having a particle size of 30 μm and the copper particles having a particle size of 30 μm is as follows.
3.5 times compared to the time B for uniformly mixing the copper particles with
It takes twice as long. This is because the smaller the particles, the more easily the particles are charged, so that the bonding force between the particles becomes electrically strong and the particles tend to be non-uniform. In order to prevent the production time from being delayed by the charging, when a copper particle having a size of 30 μm or less and a graphite particle having a size of 30 μm or less are mixed, a bonding solvent is added to the mixed particle. Then, the charged charges are released into the solvent, so that the bonding force between the particles is weakened. Further, the particles are in the solvent and have fluidity, so that the particles are easily moved and uniformized. By firing the brush material in the homogenized bonding solvent, the bonding solvent is sublimated, evaporated or completely burned, for example, and disappears inside the carbon particles and the copper particles, and the bonding solvent does not become an electric resistance.

According to the second aspect of the present invention, in addition to the effects described in the first aspect of the present invention, a mixed particle of copper particles and graphite particles is dried, and the dried product is pulverized to a size of 100 μm. Therefore, the manufacturing time can be the same as 100 μm. Moreover, when forming into a brush shape, after drying,
Since crushing and compression forming into a brush shape, when manufacturing a large number of brushes, drying and crushing can be performed at once using a large amount of material, so various brush formations are manufactured by pressing the mold Therefore, when manufacturing various brushes, the manufacturing time is short and the brush can be easily manufactured.

Further, according to the third aspect of the present invention, in addition to the contents described in the first and second aspects of the invention, the pigtail for supplying power to the brush body can be formed at the same time. Since the process is simplified, and baked after compression, a part of the pigtail and the copper particles are melt-bonded, so that the bonding strength between the brush body and the pigtail is improved.

Further, according to the invention of claim 4, in addition to the contents described in the function and effect of the invention of claim 1, since a paraffinic hydrocarbon solvent is used, when the solvent attached to the brush is fired, Easy to burn completely. Therefore, the solvent hardly remains on the surfaces of the copper particles and the graphite particles, and the current resistance hardly occurs.

Further, according to the fifth aspect of the present invention, in addition to the contents described in the function and effect of the first aspect of the present invention, from the graphs shown in FIGS. When the content is 50% to 90%, both the slidability and the voltage supply amount satisfy the performance.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to an embodiment shown in the drawings. FIG. 1 is a cross-sectional view showing the inside of a motor 2 using a brush 1 according to the present invention, and FIG. 2 is a perspective view of the brush 1 and an explanatory diagram showing a particle state thereof according to an embodiment of the present invention. FIG. 3 is a graph showing a change in slidability when the copper content of the brush is changed in the embodiment, and FIG. 4 is a graph showing a voltage when the copper content of the brush is changed in the embodiment. FIG. 5 is a flow chart showing a flow of a brush manufacturing process according to the embodiment. FIG. 6 is a graph showing a mixture of copper particles having a particle size of 30 μm and graphite particles having a particle size of 30 μm. Time A until uniform, copper particles having a particle size of 100 μm and a particle size of 10
Time B until the powder mixture with 0 μm graphite particles is made uniform
It is the graph which compared with FIG.

The brush 1 according to the embodiment of the present invention is a motor 2
Used in The motor 2 is of a direct current type having a brush 1. The brush 1 is housed in a rectangular parallelepiped brush holder 3, and the brush 1 is always commutated in the direction of the commutator 4 by the pressing force of a coil spring (not shown) in the brush holder 3. 4 is in contact with each commutator piece. The commutator 4 is rotatably integrated with a rotating shaft 5, an iron core 6 as an armature is rotatably integrated with the rotating shaft 5, and a winding 7 for generating electromagnetic force is wound around the iron core 6. And winding 7 is commutator 4
Are connected so as to be able to conduct electricity. A permanent magnet 8 that generates magnetism is provided on the outer periphery of the iron core 6, and the rotating shaft 5
Is rotatably supported via two bearings 9, and the bearings 9 are fixed to a housing 10.

In FIG. 1, a brush 1 according to an embodiment of the present invention is inserted into a rectangular parallelepiped brush holder 3. As shown in FIG. 2, the brush 1 is composed of graphite particles 11 having a particle diameter of 30 μm indicated by black circles and copper particles 12 having a particle diameter of 30 μm indicated by hatched circles. And these two types of particles are gathered to form aggregated particles 13 of 100 μm. The brush 1 is formed by compression molding and sintering the particles of 100 μm. Next, FIG. 3 shows that when the particle size of the graphite particles and the copper particles is set to the above-mentioned size, the content (% by weight) of the copper particles and the graphite particles is changed, and the slidability ratio at that time is changed. It is a graph shown. FIG. 4 shows the ratio between the voltage supply amount and the content (% by weight) of the copper particles and the graphite particles when the particle sizes of the graphite particles and the copper particles are set to the above-mentioned sizes. FIG. In each graph, the brush data of the embodiment of the present invention is shown, and is the brush data shown in the conventional art. Judging from the two graphs, in an example embodiment using the present invention, the copper content was about 50% by weight
It can be said that this is an appropriate value for improving the slidability and the voltage supply amount by up to 90%.

Next, a method of manufacturing the brush 1 of the first embodiment will be described. FIG. 5 is a flowchart showing the flow of the manufacturing method. First, a binder which is a bonding solvent for bonding the two particles with the 30 μm graphite powder, the 30 μm copper lead powder, and the like is prepared. The binder is non-phenolic and is a solvent for paraffinic hydrocarbons. These three materials are mixed in one container, and are stirred and kneaded. The kneaded mixture is dried when the three materials are thoroughly kneaded and the three materials become uniform. By this drying, volatile substances of the joining solvent are not released. Then, the dried dry substance is pulverized and pulverized so as to be aggregated particles 13 having a particle size of about 100 μm. The aggregated particle size 13, which is a crushed substance, is inserted into a mold for forming a brush shape. At this time, the aggregate of the aggregated particles 13 is put in the mold. Then, an end of a pigtail for supplying power to the brush is inserted into the above-mentioned assembly, and the assembly is compression-formed by a mold press. A compact formed from an aggregate of aggregate particles of graphite particles and copper particles formed by compression is formed into a brush shape. This brush shape is a temporary brush,
There is a possibility that a paraffinic hydrocarbon is slightly attached to the surface of the copper particles. This slight adhesion is a resistance to the brush body, so that the brush is sintered to completely remove the joining solvent. The sintering is performed for a time and at a temperature at which the joining solvent is carbonized and completely burned. Then, the surface of the brush is cut and shaped so that the dispersion at the time of forming the brush is eliminated and the brush can be reliably inserted into the brush holder, and the brush is completed.

Here, an experiment was conducted in which the copper powder and the graphite powder collected in the same weight% ratio were agitated and homogenized, and the time for homogenization is shown in FIG. A is 30 μm used in the prior art.
m is the time of the step of mixing and stirring the copper particles and the 30 μm graphite particles at a time to make them uniform, and B represents the 30 μm graphite particles 11 and the 30 μm copper particles 12 used in the present invention.
And after uniformly bonding with a bonding solvent, and then dried,
This is the time of the process until it is pulverized into the aggregated particles 13 of 100 μm. As can be seen from the graph, even in the case of the present invention in which the number of steps is large, the manufacturing time is three times shorter than in the conventional method. The following can be considered as the reason for this. This is because the smaller the particles, the more easily the particles are electrically charged, so that the bonding force between the particles becomes electrically strong and the particles tend to be non-uniform. 30 μm
When the following copper particles and graphite particles of 30 μm or less are mixed, a bonding solvent is added to the mixed particles. Then, the charged charges are released into the solvent, so that the bonding force between the particles is weakened. Further, the particles are in the solvent and have fluidity, so that the particles are easily moved and uniformized. By baking the brush material in the homogenized bonding solvent, the bonding solvent sublimates, evaporates or completely burns, for example, and the graphite particles 1
1 and the copper particles 12 are eliminated, and the bonding solvent does not become an electric resistance.

[0020]

As is apparent from the above description, according to the present invention, it is possible to obtain a brush in which copper powder and graphite powder are uniform with the same production time, and a brush which can reduce both voltage drop and frictional force can be solved. can get.

[Brief description of the drawings]

FIG. 1 is a sectional view of a motor using a brush according to an embodiment of the present invention.

FIG. 2 is a perspective view of a brush according to an embodiment of the present invention and an explanatory diagram showing details thereof;

FIG. 3 is a graph showing slidability when the content of copper particles in the brush of the embodiment of the present invention is changed.

FIG. 4 is a graph showing a voltage supply amount when the particle size of graphite particles and the particle size of copper particles in the brush of the embodiment of the present invention are changed.

FIG. 5 is a flowchart showing a flow when manufacturing an embodiment of the present invention.

FIG. 6 is a graph showing the time when 30 μm copper particles and 30 μm graphite particles are mixed at a time and uniformity and the time when 100 μm aggregated particles are uniform.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Brush 11 ... Graphite particle 12 ... Copper particle 13 ... Aggregated particle 2 ... Motor 3 ... Brush holder 4 ... Commutator.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masayuki Kuwano 390 Umeda, Kosai-shi, Shizuoka Prefecture Asmo Stock Company In-house (72) Inventor Yasuhide Ito 390 Umeda, Kosai-shi, Shizuoka Prefecture Asmo Stock Company In-house F-term (reference) 5H613 BB04 BB14 GB08 GB13 GB16 KK02 KK15 5H623 BB07 GG11 HH01 JJ01

Claims (5)

[Claims] A brush for contacting a commutator and supplying power to a motor, comprising a graphite particle having a particle size of 30 μm or less and a particle size of 30 μm.
A brush which is uniformly mixed using a bonding solvent for bonding copper particles having a particle size of m or less, and is baked so as to eliminate the bonding solvent. 2. A brush for contacting a commutator and supplying power to a motor, comprising: a graphite particle having a particle size of 30 μm or less;
m, and uniformly mixed with a bonding solvent for bonding with copper particles having a particle size of less than m, the mixture is dried, and the dried mixture is pulverized into aggregated particles having a particle size of 100 μm or more, and the aggregated particles are compression-molded into a brush shape. And a brush obtained by firing the compressed product so as to eliminate the bonding solvent. 3. A brush for contacting a commutator and supplying power to a motor, comprising: graphite particles having a particle size of 30 μm or less;
m and uniformly mixed with a bonding solvent for bonding copper particles having a particle size of not more than m, and drying the mixture, pulverizing the dried mixture into aggregate particles having a particle size of 100 μm or more, and feeding the aggregate particles to the brush body. A brush formed by compression-molding into a brush shape while inserting one end of a pigtail, firing the compression-formed product so as to eliminate the bonding solvent, and cutting the fired product. 4. The brush according to claim 1, wherein the joining solvent uses a paraffin-based hydrocarbon solvent. 5. The brush according to claim 1, wherein the weight percentage of the copper particles with respect to the brush is 50 to 90%.