JPH0538098A - Carbon current collector - Google Patents

Abstract

PURPOSE:To obtain an abrasion resistant carbon current collector having low electric resistance which scarcely cause abrasion of counterpart member by filling the pores of a porous metallic member having coupling skelton with carbon and integrating them to produce a composite member for constituting the carbon current collector. CONSTITUTION:In a method for filling the pores of a porous metallic member having coupling skelton With carbon and integrating them to produce a composite member, mixture powder of carbon and binder is filled while vibrating or the mixture powder is brought into slurry state and slid. It is then subjected to spray impregnation or low pressure impregnation to fill the carbon in the pores of the porous metallic member which is then pressed and dried, as required, to be sintered. In case of laminated structure, a layer of porous metallic material filled with the mixture of carbon powder and binder and a layer of only the carbon powder and the binder are laminated alternately and then it is pressed and dries, as required, to be sintered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon current collector used in motors and power generators.

[0002]

2. Description of the Related Art Carbon brushes are widely used as current collectors for various motors and power generators mounted on automobiles.

Since carbon brushes have low frictional resistance,
Since the current can be smoothly collected during sliding and it has abrasiveness, it has an advantage that the contact resistance is always kept at a low level.

On the other hand, since the carbon brush has an electric resistance which is not sufficiently small, it has a problem that heat generation and power loss are large when a large current is required.

In order to solve such a problem, it has been practiced to combine carbon powder or fiber as a filler with carbon, but in this method, if an amount of copper necessary for reducing electric resistance is added, There is also a problem that the hardness of the brush becomes excessively high, and the intermittent contact with the commutator, which is the mating material, accelerates the wear of the mating material, and at the same time, promotes the falling wear due to the reduced strength of the brush.

In order to solve such a problem, carbon is impregnated with a resin for reinforcement, but this method has a problem of increasing electric resistance.

In particular, in recent years, maintenance-free use is required for automobile applications and the like, and the need for a current collector having a small electric resistance and a small amount of wear is increasing.

Therefore, the present invention is intended to provide a carbon current collector having a low electric resistance, a small amount of wear, and a mating material which is hard to wear.

[0009]

In order to solve the above problems, the present invention constitutes a carbon current collector by a composite body in which carbon is filled in the voids of a metal porous body having a connecting skeleton and integrated. I did.

[0010]

In order to reduce the electric resistance of the carbon current collector, it is effective to combine it with a metal whose electric resistance is smaller than that of carbon. However, in order not to accelerate the wear of the commutator, the amount of the metal to be combined is required. It is important to keep it to a minimum.

In the conventional method of combining metal fillers, the metal fillers are randomly present in the composite, and the fillers are almost in point contact with each other. Therefore, as described above, a large amount of metal filler is required to sufficiently reduce the electric resistance.

On the other hand, in a metal porous body having a continuous skeleton, the metal skeletons forming the porous body are three-dimensionally continuous with a certain regularity, and the contact portions between the skeletons are also in contact with each other. It has a cross-sectional area of the same thickness as the skeleton part. Therefore, since there is no portion that becomes a neck of electric conduction in the porous body, a low metal content and a low electric resistance are realized.

[0013]

EXAMPLES As the metal porous body having a connecting skeleton used in the present invention, as shown in Japanese Patent Publication No. 57-39317, a foamed resin having continuous ventilation holes is subjected to a conductive treatment and then electroplated. A porous metal body having a three-dimensional network structure having a skeleton connected in a mesh shape as shown in FIG. 1 which can be manufactured by the above-mentioned method, and FIG. 2 which can be manufactured by sinter-bonding metal fibers. There is a fibrous metal porous body as described above, or a cloth-like metal porous body which can be manufactured by subjecting a woven fabric or a nonwoven fabric to a conductive treatment and then electroplating.

Further, as the material of the metal porous body, due to its low aggression with respect to the commutator and high conductivity,
Nickel, copper, silver, or alloys thereof, or combinations thereof are preferred.

If the thickness of the skeleton of the metal porous body is too thick, it will cause galling on the commutator, so that the thickness is 100 μm.
The following is preferable.

The metal content of the composite should also be selected from the balance of electrical conductivity, mechanical strength, and aggressiveness to commutators. From this viewpoint, the metal content may be 30% or less in the final molded product. preferable.

The composite structure of carbon and porous metal has a structure in which the voids of the porous metal are filled with carbon and integrated, or a layer of a composite in which the voids of the porous metal are filled with carbon and integrated. It is effective to alternately laminate the above and carbon layers alternately and integrally, and to compress and form these.

As a method for manufacturing a composite by filling carbon in the voids of a metal porous body and integrating them, a mixed powder of carbon and a binder is vibratingly filled, or a mixed powder of carbon and a binder is slurried. After putting it in the state, rub it in,
There is a method of impregnating and filling carbon into the voids of the porous metal body by spray impregnation or reduced pressure impregnation, followed by press molding, drying if necessary, and then firing. Further, in the case of a laminated structure, the same porous metal body as used in the above-described composite production is impregnated and filled with a mixture of carbon powder and a binder, and only the carbon powder and the binder are included. It can be carried out by alternately stacking layers, press-molding, drying if necessary, and then firing.

Next, concrete examples of the present invention and test results are shown below.

(1) Thickness 20 mm, average pore diameter 400 μm,
The carbon powder was mixed with acetone solution of phenol resin and slurried into the pores of a three-dimensional net-structured metal porous body made of copper, nickel and silver with a skeleton thickness of 70 μm (Sumitomo Electric “Celmet”). After filling, it was press-molded at a pressure of about 800 kg / cm ² and dried. After being sufficiently dried, it was baked in vacuum at 950 ° C. for 30 minutes to obtain a composite. A 9 mm × 12 mm × 22 mm brush was cut out from these composites and a sliding test was conducted at 300 rpm for 5 hours. The results are shown in Table 1.

As a comparative example, the results of using a brush of the same size in which 40% of a copper powder having a particle size of about 250 μm is compounded are also shown.

[0022]

[Table 1]

(2) Phenol with carbon powder is applied to a metal porous body obtained by sintering copper fibers having a thickness of 2 mm and a skeleton thickness of 60 μm or a copper woven cloth-like metal porous body sheet having a thickness of 1 mm and a skeleton thickness of 50 μm. Approximately 800 kg / cm, each of which was mixed with an acetone solution of resin and rubbed into a slurry state and filled with 5 sheets of carbon temporary molding, alternately
^It was press molded at a pressure of ² and dried. After this, the same baking treatment as in (1) was performed, then the same brush was cut out and the same test was performed. The results are shown in Table 2.

[0024]

[Table 2]

[0025]

As described above, according to the present invention, it is possible to obtain a carbon current collector having a low electric resistance, a small amount of wear, and a mating material which is hard to wear.

[Brief description of drawings]

FIG. 1 Enlarged view of a three-dimensional network porous metal body

FIG. 2 is an enlarged view of a fibrous porous metal body.

Claims (8)

[Claims] 1. A carbon current collector comprising a composite body in which carbon is filled and integrated in a void portion of a metal porous body having a connecting skeleton. 2. A carbon current collector in which the porous metal body according to claim 1 is a porous body having a three-dimensional network structure. 3. A carbon current collector, wherein the porous metal body according to claim 1 is a fibrous porous metal body obtained by sintering-bonding metal fibers. 4. A carbon current collector, which is a cloth-like metal porous body obtained by subjecting a woven or non-woven fabric to a conductive treatment and then electroplating the metal porous body according to claim 1. 5. A carbon current collector in which a layer of the composite according to claim 1 and a carbon layer are laminated and integrated. 6. The metal porous body according to claim 1 is nickel,
A carbon current collector that is copper, silver or an alloy thereof, or a combination thereof. 7. A carbon current collector in which the skeleton thickness of the porous metal body according to claim 1 is 100 μm or more. 8. The content of the porous metal body according to claim 1 is 3
A carbon current collector that is 0% or less.