Carbon brush having a centering sleeve

Abstract

The invention relates to a carbon brush (2), having a wear limit indicating function, having a current-carrying stranded wire being arranged in the brush body (4), and having a stranded indicating wire (10), which, at a stranded wire end section (12), is surrounded and fixed by a sleeve (8) having an infeed opening (22), wherein the sleeve (8) is arranged in a recess (6) being formed in the brush body (4). The sleeve (8) is formed as a centering sleeve, the inner diameter (26a, 26b) of which at the infeed opening (22) nearly corresponds to the outer diameter (24) and features a tapering (30) that is conical in the infeed direction.

Claims

1. A carbon brush (2), having a wear limit indicating function, comprising: a current-carrying stranded wire (9) carrying an operating current and being arranged in a brush body (4), and a brush-wear stranded indicating wire (10), wherein the brush-wear stranded indicating wire (10) includes a stranded wire end section (12) that is surrounded and fixed by a sleeve (8) having an infeed opening (22), wherein the sleeve (8) is arranged in a recess (6) being formed in the brush body (4), wherein the sleeve (8) is formed as a centering sleeve (8), said centering sleeve (8) has an inner diameter (26a, 26b), which at the infeed opening (22) corresponds to an outer diameter (24) and features a tapering (30) that is conical in an infeed direction, wherein the conical tapering (30) of the inner diameter (26a, 26b) is confined to a section adjoining the infeed opening (22) and wherein the centering sleeve (8) includes a section (32) having a constant inner diameter (26b) adjoining the conical tapering (30).

2. The carbon brush according to claim 1, wherein a cone angle (α) of the centering sleeve (8) corresponds to a point angle of a centering drill.

3. The carbon brush according to claim 1, wherein the centering sleeve (8) is configured as the centering sleeve (8) being closed on one side.

4. The carbon brush according to claim 1, wherein the centering sleeve (8) is configured as the centering sleeve (8) being open on both sides.

5. The carbon brush according to claim 1, wherein the brush-wear stranded indicating wire (10) and the centering sleeve (8) are pressed together by crimping or in that said brush-wear stranded indicating wire (10) is glued into place in the centering sleeve (8).

6. The carbon brush according to claim 1, wherein the centering sleeve (8) is glued into place in the recess of the brush body (4).

7. The carbon brush according to claim 1, wherein the centering sleeve (8) is produced from a manufacturing material that does not conduct electricity.

8. The carbon brush according to claim 6, wherein the centering sleeve (8) is comprised of metal, wherein an adhesive material that does not conduct electricity is used as an insulating sheathing when gluing the centering sleeve (8) into place in the recess (6) of the brush body (4), and wherein the centering sleeve (8) is configured as the centering sleeve (8) being open on both sides.

9. The carbon brush according to claim 1, wherein the brush-wear stranded indicating wire (10) and the centering sleeve (8) are fixed in the recess (6) by tamping them down with a tamping powder (15).

10. The carbon brush according to claim 1, wherein the stranded wire end section (12) includes a plurality of exposed single wires (14) being surrounded by an insulating tamping powder (15) to fix the brush-wear stranded indicating wire (10) and the centering sleeve (8).

11. The carbon brush according to claim 1, wherein the centering sleeve (8) is utilized as the centering sleeve (8) that is made of a conductive manufacturing material for coupling the current-carrying stranded wire to the brush body (4).

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

(1) Preferably, the centering sleeve is utilized as a sleeve that is made of a conductive manufacturing material for coupling the current-carrying stranded wire to the brush body. Using a sleeve in a configuration as a centering sleeve is not confined to fastening a stranded indicating wire, but can rather also advantageously be utilized in the form of a metal sleeve for producing a mechanical and electrical coupling of the current-carrying stranded wire.

(2) Further advantageous design features result from the following description and from the drawings, which explain a preferred embodiment of the invention by reference to examples. In the figures:

(3) FIG. 1a: shows a part of a carbon brush having a stranded indicating wire being stripped from its insulation in its stranded wire end section and having a centering sleeve in accordance with the invention,

(4) FIG. 1b: shows a part of a carbon brush having a stranded indicating wire not being stripped from its insulation and having a centering sleeve in accordance with the invention,

(5) FIG. 2: shows a centering sleeve in accordance with the invention in a detailed illustration,

(6) FIG. 3: shows a part of a carbon brush having a stranded indicating wire being tamped down.

(7) FIG. 4: shows a centering sleeve being open on both sides.

DETAILED DESCRIPTION OF THE INVENTION

(8) FIG. 1a shows a carbon brush 2 having a carbon brush body 4, which features a recess 6. Preferably, the recess 6 is formed as a bore, into which a centering sleeve 8 in accordance with the invention has been inserted. The centering sleeve 8, in turn, receives a stranded indicating wire 10. Here, a stranded wired end section 12 of the stranded indicating wire 10 is coupled to the centering sleeve 8, preferably, the stranded wire end section 12 and the centering sleeve 8 are pressed together by crimping or the stranded wire end section 12 is stuck together with the centering sleeve 8. Besides, the carbon brush body 4 additionally features a further recess (7) for receiving a current-carrying stranded wire (9), via which the operating current is fed in, being transferred onto a slip ring via a contact surface at the lower end of the carbon brush 2.

(9) The centering sleeve 8 itself has been glued into the recess 6, preferably with the aid of insulating adhesive material, and produces a cup-shaped insulating socket for the stranded wire end section 12 of the stranded indicating wire 10, wherein, at the end of the stranded wire end section 12, the single wires 13, 14 that are uncovered by stripping them from their insulation protrude into the interior 20 (FIG. 2) of the centering sleeve 8 like bundles. As wear of the carbon brush body 4 advances during the operation of the carbon brush 2, the contact surface of the carbon brush body 4 contacting the slip ring is shifted towards the lower end of the centering sleeve 8, such that the tip of an insulating bottom 16 of the centering sleeve 8 is also affected by the abrasion and, that the single wires 13, 14 contact the brush body 4 via the slip ring as wear advances further, whereby a warning signal is triggered.

(10) FIG. 1b shows a further exemplary embodiment, which only differs from the configuration in FIG. 1a in that the stranded indicating wire 10 is not stripped from its insulation in its stranded wire end section 12, but rather features an insulating coating or molded-on portion.

(11) FIG. 2 shows a centering sleeve 8 in accordance with the invention in detail. The centering sleeve 8—which is not illustrated to scale—is produced from a manufacturing material not conducting electricity and possesses the shape of a cylindrical base body 18 having a hollow space or interior 20, which, at the lower end, is limited by the bottom 16 being tapered and, at the upper end, features an infeed opening 22 for the stranded indicating wire 10. This cup-shaped design constitutes an insulated socket for the stranded wire end section 12 of the stranded indicating wire 10 within the carbon brush body 4. The cylindrical base body 18 features a constant outer diameter 24 as well as an inner diameter 26a, which, at the infeed opening 22, nearly corresponds to the outer diameter 24, such that the wall thickness and, hence, the front surface approach zero there. In particular with the centering sleeve 8 having been inserted into the carbon brush body 4, feeding the stranded indicating wire 10 in is significantly simplified in this way. The bundle 14 of single wires 13, 14 initially slides along in the bore 6 in the carbon brush body 4 and then advances into the interior 20 of the centering sleeve 8 up to the bottom thereof without experiencing the resistance of a stepped ledge.

(12) An inner cone 30 narrowing towards the sleeve bottom 16 abuts on the infeed opening 22, which cone guides the single wires 14 and, in the further progress, fades into a section 32 having a constant inner diameter 26b. In contrast to known wire end sleeves, which feature a conical flange, the centering sleeve 8 in accordance with the invention can completely be inserted into a bore 6 of the carbon brush body 4 in an advantageous manner.

(13) The hollow space 20, in a simple manner in terms of manufacture, is shaped by drilling with the aid of a centering drill, such that, for the cone angle α, a value results that can be selected so as to correspond to the point angle of the centering drill. A cone angle α of 30° has proved to be favorable in order to be able to feed in the stranded wire end section 12 without having to fear the risk that the single wires 13, 14 be turned out. By implication, other cone angles α are also possible—even cone angles α being independent from a drill geometry, as long as feeding in the stranded wire end section 12 works easily and the advantage of shaping the cone by the centering drill is renounced.

(14) In a simplified manner, the centering sleeve 8 can also be configured as a sleeve being open on both sides, not having a bottom 16 (see FIG. 4), if it is ensured that the exposed single wires 13, 14 do not contact the brush body 4. This can, for instance, be achieved by an adhesive material that does not conduct electricity and that has been introduced into the recess 6 before, for fixing the centering sleeve 8, the adhesive material completely lining the recess 6 in an insulating manner.

(15) In an alternative design, the centering sleeve 8 can consist of a conductive manufacturing material, wherein an adhesive material that does not conduct electricity is used as an insulating sheathing when gluing the centering sleeve 8 into place in the recess 6 of the brush body 4. In this configuration, the insulating effect of a centering sleeve 8 having been produced from an insulating (plastic) material is replaced by the glue layer.

(16) Furthermore, the centering sleeve 8 in accordance with the invention can also be utilized as a sleeve consisting of a conductive manufacturing material for coupling a current-carrying stranded wire to the brush body 4. In this arrangement for fixing the current-carrying stranded wire, too, the conical design 30 at the infeed opening 22 causes a simplified infeed of the current-carrying stranded wire. In this case, the centering sleeve 8 can also be configured as a sleeve being open on both sides, since a sheathing insulation within the brush body 4 is not required—in contrast, such an insulation even has to be avoided.

(17) FIG. 3 shows a carbon brush 2 having a carbon brush body 4, in the recess 6 of which the stranded indicating wire 10 that is arranged in the centering sleeve 8 in accordance with the invention is tamped down. The centering sleeve 8 is formed as a sleeve consisting of an insulating material and being closed on one side, as in FIG. 1a, and receives the stranded wire end section 12 of a stranded indicating wire 10 not being coated in this embodiment. Here, the bundle 14 of exposed single wires 13, 14 protrudes into the interior of the centering sleeve 8 and is stuck together with an adhesive layer 17 there. Alternatively, crimping or pressing is also possible—depending on the material properties of the sleeve 8. The arrangement consisting of the stranded indicating wire 10 and of the centering sleeve 8 is fixed with the aid of an insulating tamping powder 15 above the infeed opening of the centering sleeve 8.