JP2005304115A - Metal graphite brush - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal graphite brush capable of reducing an electric loss without increasing electric resistance at a lead wire burying part and without impairing sliding characteristics. <P>SOLUTION: In the metal graphite brush having a three-layer structure of a high resistance layer principally composed of copper and graphite, an intermediate resistance layer and a low resistance layer with a lead wire buried in the low resistance layer, the low resistance layer contains 1-10 wt% of zinc. It is preferably satisfied in resistivities of the three layers that: the high-resistance layer > the intermediate resistance layer > the low-resistance layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electric brush for a rotating electrical machine used for an electric motor, a generator, and the like, and more particularly, to a metal-graphite electric brush for an automobile starter motor.

  The electrical loss of an electric brush used for a rotating electrical machine greatly affects the efficiency of the entire rotating electrical machine. For this reason, in a rotating electrical machine that requires high output and high efficiency, it is desirable that the electrical loss of the electric brush is as low as possible.

  As a means for reducing the electrical loss of the electric brush, it is effective to contain a metal in the electric brush, increase the metal content, and lower the resistivity of the electric brush body. However, since the electric brush is a sliding material, increasing the content of a metal having poor lubricity deteriorates the sliding characteristics and increases the amount of wear, resulting in a problem that the life of the rotating electrical machine is shortened. In addition, there is a problem that the electric brush becomes high temperature due to the operation of the rotating electric machine, the electrical resistance of the lead wire embedded portion increases, and the electrical loss increases.

  As a means for satisfying the conflicting required characteristics of reducing the electrical loss and reducing the amount of wear, as described in Patent Document 1, a plurality of electric resistances of the high resistance layer and the low resistance layer are different. As described in Patent Document 2, the commutation performance is improved by configuring the layers of the above, and the amount of spark generation is reduced, and the amount of wear is reduced without increasing the contact voltage drop with the commutator. There is a method of reducing the electrical loss of the lead wire embedded portion by constructing the electric brush from the high resistance layer and the low resistance layer and embedding the lead wire in the low resistance layer without touching the high resistance layer. .

JP 09-049478 A Japanese Patent Laid-Open No. 04-500580

  However, in the method as described above, if the amount of graphite is increased in order to improve the sliding characteristics of the electrobrush, the electrical loss also increases, which is essential in that the balance with the sliding characteristics is limited. It has not changed.

  The present invention provides a metal graphite electric brush that can reduce electrical loss without increasing the electrical resistance of the lead wire embedded portion and without impairing the sliding characteristics.

  The present invention has a three-layer structure including a high resistance layer mainly composed of copper and graphite, a medium resistance layer, and a low resistance layer, and a metal graphite electrobrush in which lead wires are embedded in the low resistance layer. The present invention relates to a metal graphite electrobrush comprising 1 to 10% by weight of zinc in a low resistance layer.

  The electric brush of the present invention is extremely industrially preferable because the electric resistance of the lead wire embedded portion does not increase and the electric loss can be reduced without impairing the sliding characteristics.

  As shown in FIG. 1, the electroprinter according to the present invention includes a high resistance layer 1, a medium resistance layer 2, a low resistance layer 3 and a lead wire 4, and the low resistance layer 3 in which the lead wire 4 is embedded. A material containing zinc is used.

  The zinc content is in the range of 1 to 10% by weight, preferably in the range of 2 to 8% by weight in the total composition constituting the low resistance layer 3, and the lead wire with the zinc content of less than 1% by weight. The electrical resistance of the buried portion is easily changed and electric loss increases. On the other hand, if it exceeds 10% by weight, the electrical resistance value at the initial stage of the lead wire embedded portion becomes high and the electrical loss increases.

  The resistivity of each of the high resistance layer 1, the medium resistance layer 2 and the low resistance layer 3 is not particularly limited as long as the relationship of high resistance layer 1> medium resistance layer 2> low resistance layer 3 is satisfied. In order to satisfy the relationship of the rate, for example, the resistivity of the high resistance layer 1 is preferably about 2 to 20 times, more preferably about 4 to 16 times, more preferably about 8 to 12 times that of the middle resistance layer 2. Is more preferable.

  Further, the resistivity of the low resistance layer 3 is preferably 2/3 or less, more preferably 1/2 or less, and further preferably 1/3 or less of the resistivity of the medium resistance layer 2. In addition, since the middle resistance layer 2 is a part that determines most of the performance of the electric brush, the resistivity is set in accordance with the required characteristics of the rotating electric machine to be used, but generally 0.1 to 30 μΩ. -The value is about m. The resistivity of each of these layers is appropriately selected by adjusting the amount of copper powder to be contained in an electric brush mainly composed of graphite.

Examples of the present invention will be described below.
Example 1
80% by weight of natural graphite having an average particle size of 50 μm (trade name CB-150, manufactured by Nippon Graphite Industries Co., Ltd.) and 20% by weight of resol type phenol resin (trade name VP-11N, manufactured by Hitachi Chemical Co., Ltd.) After kneading, it was dried at 65 ° C. for 16 hours and then pulverized to obtain a resin-treated graphite powder having an average particle size of 150 μm.

Next, 45% by weight of the resin-treated graphite powder and 55% by weight of electrolytic copper powder having an average particle size of 35 μm (trade name CE-25, manufactured by Fukuda Metal Foil Industry Co., Ltd.) are mixed for 30 minutes with a mixer. A blended powder for the resistance layer was obtained. On the other hand, 65% by weight of the resin-treated graphite powder obtained above and 35% by weight of the electrolytic copper powder used above were mixed with a mixer for 30 minutes to obtain a blended powder of a high resistance layer.
In addition, the resin-treated graphite powder obtained above, the electrolytic copper powder used above, and the zinc powder having an average particle size of 30 μm are weighed in the proportions shown in Table 1, and mixed for 30 minutes with a mixer to mix the low resistance layer. I got a powder.

  Next, each blended powder obtained above is filled separately in predetermined positions of the mold, and further, lead wires are installed at the locations to become the low resistance layer, and then integrally molded with a molding press at a pressure of 392 MPa. Then, the temperature was raised to 700 ° C. in a reducing atmosphere in 3 hours, sintered at 700 ° C. for 1 hour, and then the predetermined shape, that is, the middle resistance layer portion was 16 × 8 × thickness 5.4 mm, high resistance 1 is obtained by machining so that the layer portion is 16 × 8 × 1.6 mm thick and the low resistance layer portion is 16 × 7 × 7 mm thick. It was. When the resistivity of the obtained metal graphite electric brush was measured, the high resistance layer was 3.5 μΩ · m, the middle resistance layer was 0.4 μΩ · m, and the low resistance layer 3 was 0.1 μΩ · m.

  In addition, the resistivity is measured by molding each compounded powder under the same conditions as described above, sintering, and machining to prepare a test piece having a size of 5 × 5 × 20 mm, and 1A in the direction of 20 mm. The voltage drop between 10 mm when the current was passed was measured and calculated by the following formula. Here, in the test specimen for measurement, the 20 mm direction was set to the direction perpendicular to the molding pressure.

Examples 2-6
The resin-treated graphite powder obtained in Example 1, the electrolytic copper powder used in Example 1 and the zinc powder having an average particle size of 30 μm are weighed in the proportions shown in Table 1, and mixed in a mixer for 30 minutes to form a low resistance layer Of powder was obtained. Thereafter, the obtained mixed powder for the low resistance layer and the mixed powder for the medium resistance layer and the mixed powder for the high resistance layer obtained in Example 1 were separately filled in predetermined positions of the mold, respectively. Through the same steps as in Example 1, a metal graphite electrobrush having the same shape as in Example 1 was obtained.

Comparative Example 1
The resin-treated graphite powder obtained in Example 1 and the electrolytic copper powder used in Example 1 are weighed in the proportions shown in Table 1, and mixed with a mixer for 30 minutes to obtain a low-resistance layer-containing powder containing no zinc. It was. Thereafter, the obtained mixed powder for the low resistance layer and the mixed powder for the medium resistance layer and the mixed powder for the high resistance layer obtained in Example 1 were separately filled in predetermined positions of the mold, respectively. Through the same steps as in Example 1, a metal graphite electrobrush having the same shape as in Example 1 was obtained.

Comparative Example 2
The resin-treated graphite powder obtained in Example 1, the electrolytic copper powder used in Example 1 and the zinc powder having an average particle size of 30 μm are weighed in the proportions shown in Table 1, and mixed with a mixer for 30 minutes to contain zinc. A blended powder of a low resistance layer having an amount of less than 1% by weight was obtained. Thereafter, the obtained mixed powder for the low resistance layer and the mixed powder for the medium resistance layer and the mixed powder for the high resistance layer obtained in Example 1 were separately filled in predetermined positions of the mold, respectively. Through the same steps as in Example 1, a metal graphite electrobrush having the same shape as in Example 1 was obtained.

Comparative Example 3
The resin-treated graphite powder obtained in Example 1, the electrolytic copper powder used in Example 1 and the zinc powder having an average particle size of 30 μm are weighed in the proportions shown in Table 1, and mixed with a mixer for 30 minutes to contain zinc. A blended powder of a low resistance layer with an amount exceeding 10% by weight was obtained. Thereafter, the obtained mixed powder for the low resistance layer and the mixed powder for the medium resistance layer and the mixed powder for the high resistance layer obtained in Example 1 were separately filled in predetermined positions of the mold, respectively. Through the same steps as in Example 1, a metal graphite electrobrush having the same shape as in Example 1 was obtained.

  Next, with respect to the metal graphite electrobrushes obtained in Examples 1 to 6 and Comparative Examples 1 to 3, the voltage drop value of the lead wire embedded portion immediately after production (at 0 hour), the temperature is 80 ° C., and the humidity is 90%. Under these conditions, the change over time in the voltage drop value of the lead wire embedded portion after 100 hours, 200 hours and 250 hours was examined. The result is shown in FIG. As shown in FIG. 3, the voltage drop value of the lead wire embedded portion is a value obtained by measuring the voltage drop between CD when a current of 200 A is passed between AB.

  As shown in FIG. 2, the metal graphite electric brushes of Examples 1 to 6 according to the present invention have a time-dependent voltage drop value at the lead wire embedded portion as compared with the metal graphite electric brushes of Comparative Examples 1 to 3. It is clear that the change is small. In addition, the metal graphite electric brushes of Examples 1 to 6 and the metal graphite electric brushes of Comparative Examples 1 to 3 differ only in the components constituting the low resistance layer in which the lead wires are embedded, and the medium resistance layer and the high resistance film. Since the sliding parts of the layers are the same component, there is no difference in the sliding characteristics, so that the metal graphite electric brush of the present invention does not impair the sliding characteristics as compared with the metal graphite electric brush of the comparative example. It is clear that the electrical loss is reduced.

It is sectional drawing which shows the structure of a metal graphite electrobrush. It is a graph which shows the relationship between leaving time and the voltage drop of a lead wire embedding part. It is the schematic which shows the measuring method of the voltage drop of a lead wire embedding part.

Explanation of symbols

1 High resistance layer 2 Middle resistance layer 3 Low resistance layer 4 Lead wire

Claims (1)

In a metal-graphite electric brush having a three-layer structure including a high-resistance layer mainly composed of copper and graphite, a medium-resistance layer, and a low-resistance layer, and a lead wire embedded in the low-resistance layer, A metallic graphite electrobrush comprising 1 to 10% by weight of zinc.

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