DE892627C - Carbon brush with stranded armature - Google Patents

Description

Carbon brush with stranded armature In, the carbon brush technology are numerous Method for attaching cables (metal strands) to carbon brushes for electrical Machines known and used. Initially, the carbon brushes were made with brackets made of copper or brass sheet by screwing, riveting or soldering and the strands are then riveted or soldered to extensions of these stirrups attached. Next to. These reinforcements meant an extraordinary amount of work a waste of metal.

Later the strands were riveted directly to the carbon attached. When the carbon brushes are subjected to high loads, however, one often occurs Loosening of the rivet connection due to vibrations. This will make contact between carbon and stranded wire deteriorated, and the one at the bad contact point generated heat in turn leads to a further deterioration of the rivet contact up to a malfunction.

The type of fastening that has been used most frequently lately has finally arrived of strands. with carbon brushes, in which the end of the cable is inserted into a hole and copper powder is poured and tamped down around the cable. at These so-called rammed contacts, the connection is often destroyed purely mechanically, the powder loosens and the contact becomes unusable.

The invention brings a new fastening method, which in addition to A permanent and permanent connection between the stranded wire and the carbon brush requires little effort guaranteed both in mechanical as an electrical point of view also the highest stresses occurring in practice during the whole Withstands the service life of the carbon brush. The essence of the invention consists in one bolt shapes penetrating the brush head at right angles to the respective boundary surface Metal shrink molding graduated. Diameter through which the strand is captured and mechanically strong as well as good electrical conductivity inside the brush to the carbon material is pressed, the bore is dimensioned so that the cast metal in Longitudinal direction, d. H. in the required direction of pressure to press the braid on the coal shrinks more than in diameter.

The drawing shows some exemplary embodiments.

Fig. I shows a carbon brush with a stepped horizontal bore BH and a vertical bore Bh. The copper braid is inserted through the vertical bore BTX and shaped at its end to form an eyelet LR. This ring-shaped strand end LR rests on the inside against the wall K1 of the stepped bore. After the bore BH has been filled with molten casting compound G, the solidifying metal will shrink more strongly in the longitudinal direction than it would radially due to the dimensioning of the bore and press the strand firmly against the carbon K due to the shrinkage pressure. Under certain circumstances, the molten cast will also partially penetrate the strand, so that there is an inseparable contact.

Fig. 2 shows another possible design on a brush with two strands L2. The strand L is pulled through with two correspondingly drilled carbon heads Free protruding ends in the desired length. The entire hole. it will then filled with casting compound G2. The cast metal includes the braid as far as it is is inside the coal, penetrates it and forms with it after solidification a fixed contact arrangement seated under shrinkage pressure in the carbon head.

The possible embodiments arising from the concept of the invention are manifold and allow the most appropriate for all brush sizes and shapes Embodiment.

In Fig.3 an example is shown in which an additional hole B3 is attached, through which the pouring can take place. This additional drilling would leave The two examples according to fig. r and 2 should also be used.

Depending on the size of the coal, the number and strength of the strands, you will find the many occurring types of carbon brushes each one of the possible according to the invention Select design variants, always proceeding according to the invention in such a way that the greatest shrinkage path and thus greatest shrinkage pressure used to secure the stranded wire will.

Claims (3)

PATENT CLAIMS: i. Carbon brush with stranded fittings for electrical Machinery; characterized in that the mechanical fastening and electrical Connection between carbon and one or more strands from a brush head Bolt-shaped metal shrink-fit casting penetrating at right angles to the respective boundary surface graduated, diameter, which is dimensioned so that it according to. the pouring shrinks more in the longitudinal direction than in the diameter. 2. Carbon brush according to claim i, characterized in that the introduced through a vertical bore BV and In the horizontal bore BH, the strand end LR formed into a ring in the stepped one Horizontal bore lies and through the shrinkage pressure of the cast metal bolt G, is pressed against the coal wall Ki (Fig. I). 3. carbon brush according to claim i, characterized in that the strand L2 is the hole filled by the cast G2 B2 passes through and with the cast metal, which by shrinkage pressure on the carbon surfaces K2 sits firmly in the carbon head and is permanently connected (Fig.2). q .., carbon brush after Claims 1 to 3, characterized in that the carbon brush has an additional bore B3 has as a pouring opening, which in turn is offset so that after it has been filled with cast metal an additional shrink pressure clamping of the cast metal is reached (Fig. 3).