EP0585591A1 - Carbon brush - Google Patents

Abstract

A carbon brush (10) is proposed which has a box-shaped or cylindrical geometry with side or end surfaces in which a current-carrying (live) braided cable (12) is arranged as well as an indicating braided cable (28) which extends in the longitudinal direction of the carbon brush. The indicating braided cable is arranged and fixed in position by means of a section (26) of a recess (30), such as a hole, which preferably runs in the longitudinal direction of the carbon brush, in order to produce a signal to indicate a specific carbon brush wear level, by interacting with a commutator or slipring. In order to ensure that the indicating braided cable is fixed in position unambiguously but without being stressed, it is surrounded by a sleeve (32) having a circumferential edge (34) which, for its part, rests against a step (36) on the recess. <IMAGE>

Description

The invention relates to a carbon brush with signaling wire and preferably with a current-carrying wire arranged in the carbon brush and optionally with an isolating nipple made of insulating material and spring-loaded in the longitudinal axis of the carbon brush, the signaling wire, which is at least partially surrounded by a sleeve, with a for indicating a specific consumption of carbon brushes Carbon brush interacting commutator or slip ring for releasing a signal in electrically conductive contact is arranged in a preferably extending in the longitudinal axis direction of the carbon brush and starting from a first carbon brush surface recess such as bore.

In machines intended especially for commercial purposes, it is necessary that a signal appears before the carbon brush is worn to an unacceptable extent and is lifted off the commutator or slip ring of the motor by the shut-off nipple, indicating that the carbon brushes will soon be replaced due to their consumption Need to become. In this case, the insulation of the normally insulated signal wire or the insulating material surrounding it is rubbed off by interaction with the commutator and the slip ring, so that the signal wire itself then comes into electrically conductive contact with the commutator or slip ring, whereby a circuit is closed and the desired signal is released in a latching manner.

Signaling strands can be covered at least in some areas with Teflon or an equivalent material, at least in the section running within the carbon brush. The section is then glued into the recess. So that the signal wire cannot slip out of the adhesive material - Teflon does not accept an adhesive - on the one hand, a wavy or twisted geometry is embossed on the section surrounded by Teflon, and on the other hand the section is laid in a loop or U-shape in the recess. The installation of corresponding signal wires is clearly complex.

From FR-A 2 223 858 it is known to arrange a signaling wire in a sleeve made of insulating material, which extends at least in regions within a correspondingly adapted recess in the carbon brush. Since the signal wire itself is surrounded by an insulating jacket, problems can arise when it is clearly arranged in the sleeve.

In order to fix the sleeve itself in the carbon brush, a shoulder runs at a considerable distance from the surface of the carbon brush. This in turn means that a considerable distance has to be covered until the plastic sleeve has been moved up to this stop. If there is an inaccuracy of fit, the case can therefore occur that the sleeve can no longer be displaced at a distance from the step, so that the signaling wire would consequently indicate too late that the carbon brush must be replaced.

In EP 0 232 209 A1, optical conductors are used to detect carbon brush wear, via which light signals are transmitted or received.

A carbon brush for collector motors is known from DE 28 04 547 A1, in which a signaling wire surrounded by an insulating jacket is arranged in a longitudinal bore.

In order to position the signaling wire uniquely, suitable adhesive materials must be used. However, especially in the case of jerky bumps, it is not ensured that the signaling wire is not moved.

In order to avoid this disadvantage, a prefabricated plastic sleeve is proposed according to G 84 33 023 U1, which can be inserted into a bore in a carbon brush. The signal wire is then inserted into the plastic part itself. So that the signaling wire remains in the sleeve, it is slotted so that the signaling wire is clamped between the longitudinal halves of the sleeve which can be moved relative to one another when it is introduced into the carbon brush. If the bore for receiving the sleeve is too large compared to its outer diameter, a secure holding of the signal wire is not guaranteed. The sleeve can also melt at high temperatures, resulting in an uncontrolled displacement of the signaling wire.

The present invention is based on the object of developing a carbon brush of the type described in the introduction in such a way that the carbon brush can be fitted with the signaling wire in a manner suitable for automatic and problem-free operation, and in addition a clear, secure positional fixation, in particular with respect to the area of the signaling wire section, which is to take place with the Commutator or the slip ring for releasing the signal interacts. It should also be ensured that the position fixing of the signaling wire does not cause any stresses in the carbon brush, which can lead to inadmissible cracks, particularly in the case of laminated carbon brushes.

The object is achieved in a carbon brush of the type described in the introduction in that the sleeve has an edge which extends at least in some areas and which lies against a shoulder of the recess, in that the sleeve with its outer edge surface spaced from the assigned first outer surface of the carbon brush and that adhesive material is introduced into the space formed between the outer surface of the sleeve edge and the first carbon brush surface and / or the signaling wire is fixed in position via a further recess extending from a side surface of the carbon brush. In particular, it is provided that the sleeve is fixed in position via a pin arranged in the second recess. Tamping over the second recess is also possible.

In the case of a layered carbon brush, the second recess runs exclusively within one of the carbon brush layers.

The measures according to the invention ensure that the signal wire is securely fixed. The use of metal such as brass as the sleeve material ensures, due to its hardness, that it can be easily inserted into the carbon brush even if the geometry of the recess and sleeve are closely coordinated. The metal material also ensures problem-free gluing in the carbon brush, which would otherwise lead to considerable problems when using plastic. By squeezing like crimping the sleeve and signaling wire, it experiences an immovable and therefore clear positioning.

Due to the fact that the edge sits on the shoulder or bottom of the first recess, which is preferably a stepped bore, and metered adhesive is added to the edge of the sleeve, that is to say the sleeve is not actually glued into the bore, thermal expansion of the adhesive cannot be so great occur that would otherwise lead to cracking. Nevertheless, fixation by the adhesive is ensured, since the adhesive is drawn into the joint between the sleeve and the wall of the carbon brush recess for hardening and only a correspondingly thin adhesive layer is formed.

The additional or alternative proposal of a position fixation by means of the pin element ensures a completely tension-free fixing of the sleeve without requiring larger dimensions of the carbon brush.

The teachings according to the invention are suitable for all types of carbon brushes which have a signaling strand, i.e. those which have only one signaling strand or those which, in addition to the signaling strand, comprise only a shutdown device and / or a current-conducting helical compression spring and / or a current-conducting strand.

• a) geringe Einbaumaße,
• b) die Einbautiefe ist bei Verwendung einer einheitlichen Hülse einfach zu ändern,
• c) die Kontrolle der Einbautiefe ist einfach (ist die Hülse bis auf den Bund (flanschartiger Rand) eingeklebt, ist die Einbautiefe in Ordnung. Ein Verrutschen der Litze wird klar sichtbar;
• d) die Meldelitzenanordnung macht es möglich, die Montage zu automatisieren;
• e) spannungsfreie Verbindung, wodurch geringe Wandstärken zwischen der bzw. den Ausnehmungen und den Kohlebürstenaußenflächen genügen.

In general terms, the following advantages can be achieved with the invention:

• a) small installation dimensions,
• b) the installation depth is easy to change when using a uniform sleeve,
• c) Checking the installation depth is easy (if the sleeve is glued to the collar (flange-like edge), the installation depth is correct. Slipping of the strand is clearly visible;
• d) the signal wire arrangement makes it possible to automate the assembly;
• e) stress-free connection, as a result of which small wall thicknesses between the recess or recesses and the carbon brush outer surfaces are sufficient.

However, the object is also achieved with a carbon brush with a cuboid or cylindrical geometry with side or end faces, with one end face being able to be placed against a commutator or slip ring of an electric motor, comprising current-carrying wire arranged in the carbon brush, optionally with an insulating material that is spring-biased in the longitudinal axis of the carbon brush Shut-off nipple and a signaling wire, which extends with a section of a preferably in the longitudinal direction of the carbon brush (First) recess such as a hole is arranged and fixed in position in order to generate a signal to indicate a certain consumption of carbon brushes by interacting with the commutator or slip ring, the carbon brush being characterized in that the signaling wire extends over a (second) Recess is fixed in position. In this case, the signaling wire is preferably tamped via the second recess starting from the side surface, such as a bore in the first recess.

Alternatively, there is also the possibility of inserting a fastening element such as a screw to fix the signaling wire through the second recess.

Due to the teaching of the invention, it is no longer necessary that the bore running in the longitudinal direction of the carbon brush, within which the signal wire runs, must have a considerably larger cross section than the signal wire itself in order to introduce the material required for pounding. Rather, the longitudinal bore can be adapted to the cross-section of the signal wire, so that a sufficient residual wall thickness remains.

In contrast, the bore emanating from the side surface can have a relatively large cross-section in order to introduce and compact the powder for pounding the signaling wire through it.

The cross section of the second recess, that is to say that which should be perpendicular or approximately perpendicular to the longitudinal axis of the carbon brush, is preferably approximately 1.5 times the cross section of the first recess, which, as mentioned, is adapted approximately to that of the signaling wire.

In order to ensure a secure fixation of the position, the second recess should run at a distance L / 3 to L / 2 from the free end of the section of the signal wire running inside the carbon brush, the length of which corresponds within the carbon brush L.

Since the signal wire is cut to length before it is inserted into the carbon brush, it must be ensured that the free end is stripped. For this purpose, it can be provided that the signal wire, after it has been cut to length and optionally pretreated, is immersed in an etchant in an adhesive, preferably made of polyurethane.

Further details, advantages and features of the invention result not only from the claims, the features to be extracted from them - by themselves and / or in combination - but also from the following description of preferred exemplary embodiments which can be found in the drawing.

Fig. 1

einen Ausschnitt einer ersten Ausführungsform einer Kohlebürste,

Fig. 2

eine zweite Ausführungsform einer erfindungsgemäß ausgebildeten Kohlebürste im Schnitt und Seitenansicht,

Fig. 3

die Kohlebürste gemäß Fig. 2 in Vorderansicht,

Fig. 4

die Kohlebürste gemäß Fig. 2 in Draufsicht,

Fig. 5

eine dritte Ausführungsform einer Kohlebürste und

Fig. 6

eine vierte Ausführungsform einer Kohlebürste.

Show it:

Fig. 1

a section of a first embodiment of a carbon brush,

Fig. 2

2 shows a second embodiment of a carbon brush designed according to the invention in section and side view,

Fig. 3

2 in front view,

Fig. 4

2 in top view,

Fig. 5

a third embodiment of a carbon brush and

Fig. 6

a fourth embodiment of a carbon brush.

1 to 5, in which basically the same elements are provided with the same reference numerals, carbon brushes (10) and (60) are partially shown in the cutout, in which a current-carrying wire (12) and a shut-off nipple (14) are arranged can (Fig. 1). The shut-off nipple (14) is made of insulating material and is spring-biased in the direction of the longitudinal axis (16) of the carbon brush (10), preferably by means of a helical spring (18).

Both the stranded wire (12) and the shut-off nipple (14) are stamped in by means of powdered-in metal powder (20) or (22). An insulating plate (24), on which the helical spring (18) is supported, can additionally be arranged between the ramming powder (22) covering the shut-off nipple (14) and the end face facing it.

The elements described so far are known from the prior art and can also undergo known modifications.

A section (26) of a signaling wire (28) also runs within the carbon brush (10). A signal is to be triggered via the signaling wire (28), namely when the carbon brush (10) interacting with a commutator or slip ring (not shown) is worn to such an extent that renewal is appropriate, i.e. before the carbon brush (10) in one Extent is used that the shut-off nipple (14) lifts the carbon brush from the slip ring or the commutator.

The signaling wire (28), which in the exemplary embodiment runs in a recess parallel to the longitudinal axis (16) of the carbon brush (10), such as a stepped bore (30), is insulated. The section (26) running in the bore (30) can additionally be surrounded by teflon material (31).

The section (26) of the signaling wire (28) extending in the bore (30) extends in the longitudinal direction of the bore (30).

The section (26) of the signaling wire (28) is surrounded in regions by a sleeve (32) which has a flange-like upper edge (34) which, when mounted Signaling wire (28) abuts a shoulder (36) of the stepped bore (30).

The length of the sleeve (32) is less than the section (26) surrounded by it. Consequently, the free end (38) of the section (26) extends in a space (44) which extends between the bottom (42) of the bore (30) and the lower edge of the sleeve (32). Since the free end (38) of the signaling wire (28) is stripped, insulation can optionally be carried out with an adhesive material, in order not to generate a signal prematurely, which could otherwise be caused by carbon dust generated when the carbon brush runs off.

So that the signal wire (28) cannot slip to the sleeve (32), these are connected to each other e.g. squeezed by crimping. This area is identified in FIG. 1 by the reference symbol (40).

The flange-like edge or collar (34) is set back with respect to the free surface (46) of the side of the carbon brush (10) from which the stepped bore (30) originates.

In order to clearly position the sleeve (32) and thus the signaling wire (28), the sleeve can be fixed in position in the carbon brush using adhesive material or a pin. This will be explained with reference to FIGS. 2 to 5.

2 to 4, a layered carbon brush (60) is shown, which consists of layers (62) and (64) glued together. The stepped bore (30) for the signaling wire (28), not shown, and on the other hand an oblique bore (68) for a current-carrying wire extend from the end face (66) of the carbon brush (60).

The sleeve (32) with the signaling wire (not shown) is introduced into the bore (30), wherein the edge (34) of the sleeve (32) rests on the shoulder (36) of the stepped bore (30). This paragraph (36) can be caused by any change in cross section.

In order to rule out an uncontrolled axial displacement of the sleeve (32), a recess, such as a bore (74), extends perpendicular to the longitudinal axis (16) of the carbon brush (60) from a side surface (72) of the layer (64) of the carbon brush (60), into which a pen can be inserted. The bore (74) or the pin is dimensioned so that the pin (76) rests on the free upper surface of the edge (34).

Since the bore (74) extends exclusively in one of the layers of the carbon brush (60), there is a tension-free fixing of the position, which prevents the hairbrush from bursting apart or the formation of hairline cracks in the carbon brush (60).

The position of the sleeve (32) in the bore (30) of the carbon brush (70) according to FIG. 5 is achieved by adhesive material which is metered into the space (78) that is located between the surface (80) of the carbon brush (70). and the upper free surface of the collar (34) of the sleeve (32) extends.

Since the adhesive material - indicated by the blackened corners (82) and (84) - only after the sleeve (32) has been positioned in the bore (30), i.e. after the edge (34) lies on the shoulder (36) of the bore ( 30) is introduced, only a small amount of adhesive reaches the area between the sleeve (32) or its edge (34) and the wall of the bore (30). This in turn means that thermal expansion cannot lead to cracks.

It should also be mentioned that the position of the sleeve (32) can also be fixed in that the pin (76) does not run above the collar (34), but extends laterally along the sleeve and touches it tangentially in order to achieve a position fix . There is also the possibility of the sleeve by a side surface and Fixing the recess, preferably perpendicular to the longitudinal axis of the sleeve, by stamping carbon material into it, for example. A position fixation can also be done by, for example, a fastening element such as a screw.

FIG. 6 shows a cross section of a further carbon brush (100) designed according to the invention, which has a cuboid geometry.

Bores (114) and (116) are provided parallel to the longitudinal axis (112) of the carbon brush. A shut-off nipple (118) is arranged in the bore (114). The shut-off nipple (118) is made of an insulating material and is preferably biased in the direction of the longitudinal axis (112) of the carbon brush with a helical spring (not shown).

A current-conducting strand (120) runs coaxially with the shut-off nipple (118) and above it.

A signaling wire (122) is arranged in the longitudinal bore (116) and extends with a section (124) of length L within the bore (116). The cross section of the bore (116) corresponds approximately to that of the signaling wire (122).

The signal wire (122) is insulated within the bore (116). For this purpose, the signaling wire (122) or the section (124) has a sheathing preferably made of Teflon. The free end is insulated with an adhesive. The signaling wire (122) is cut off beforehand and pretreated with an etchant, in order to then be immersed in an adhesive which is preferably made of polyurethane.

The free end (126) of the signaling wire (122) surrounded by the adhesive runs below the shut-off nipple (118). Consequently, when the carbon brush (110) wears, the end (126) first comes into an electrically conductive connection with a commutator or slip ring (not shown) before the carbon brush (110) passes over the shut-off nipple (118) is lifted off the commutator or slip ring. The current-carrying connection between the signal wire and the commutator or the slip ring triggers a signal which indicates that the carbon brush (110) has to be replaced.

In order to fix the signaling wire (122) in the desired position within the longitudinal bore (116), a transverse bore (130) extends from a side surface (128) of the longitudinal bore (116), which is preferably perpendicular to the longitudinal axis (112) of the carbon brush (110) runs. About the cross hole (130) z. B. made of copper or iron powder or carbon introduced to tamp the signaling wire (122) or section (124), so that it immovably fix in the longitudinal bore (116). The cross section of the transverse bore (130) can be considerably larger than that of the signaling wire (122) in order to introduce and compact the powder required for pounding to the required extent.

Instead of powder to be tamped down, a screw or another fastening element can also be introduced into the transverse bore (130), by means of which the position (124) and thus the signaling wire (122) are fixed in position.

The cross section of the transverse bore (130) preferably corresponds to 1.5 times the signaling wire (122).

The transverse bore (130) should also run approximately at a distance from the L / 3 to L / 2 to the free end (126) of the section (124) of the signaling wire (122).

Claims (10)

Carbon brush (10, 60, 70) with signaling wire (26, 28) and preferably with current-carrying wire (12) arranged in the carbon brush and optionally with a shut-off nipple (14) made of insulating material and spring-loaded in the longitudinal axis of the carbon brush (16), the at least in some areas Signaling wire surrounded by a sleeve (32) with a commutator or slip ring interacting with the carbon brush to indicate a specific carbon brush consumption in order to release a signal in electrically conductive contact in a section preferably running in the longitudinal axis direction of the carbon brush and by a first carbon brush surface (46, 80 ) outgoing recess (30) is arranged like the bore,
characterized by
that the sleeve (32) has an edge (34) which extends at least in certain areas and which bears against a shoulder (36) of the recess (30), that the sleeve with its outer edge surface is spaced apart from the assigned first outer surface (46, 80) of the carbon brush ( 10, 60, 70) and that adhesive material is introduced into the space (30, 78) formed between the outer surface of the sleeve edge and the first carbon brush surface and / or the signaling wire (26, 28) is fixed in position via a further recess (74) extending from a side surface (72) of the carbon brush (60). Carbon brush according to claim 1,
characterized by
that a pin element (76) is arranged in the second recess (74), which runs preferably perpendicular to the longitudinal axis (16) of the carbon brush (60) and preferably extends above the edge (34) of the sleeve (32) and touching it. Carbon brush according to claim 1,
characterized by
that the sleeve (32) is rammed into the first recess (30) via the second recess (74), which preferably runs perpendicular to the longitudinal axis (16) of the carbon brush (60). Carbon brush according to at least one of the preceding claims,
characterized by
that the flange-like edge (34) of the sleeve (32) is arranged without play or essentially without play between the shoulder (36) of the first recess (30) such as a stepped bore and the pin element (76). Carbon brush according to at least one of the preceding claims,
characterized by
that extends within the second recess (74), the sleeve (32) position-fixing pin element (76). Carbon brush according to at least one of the preceding claims, wherein the carbon brush is a layered carbon brush (60),
characterized by
that the second, preferably perpendicular to the longitudinal axis (16) of the carbon brush (60) extending recess (74) runs exclusively within one of the carbon brush layers (62, 64). Carbon brush according to at least one of the preceding claims,
characterized by
that the sleeve (32) with the signal wire (26, 28) is squeezed. Carbon brush (110) with a cuboid or cylindrical geometry with side or end faces, one end face being able to be placed against a commutator or slip ring of an electric motor, comprising current-carrying wire (120) arranged in the carbon brush, optionally a shut-off nipple made of insulating material and spring-biased in the longitudinal axis of the carbon brush (118) and a signaling wire (122), which is arranged and fixed in position with a section (124) of a (first) recess (116), preferably extending in the longitudinal direction (112) of the carbon brush, in order to indicate a specific consumption of carbon brushes by interacting with generate a signal to the commutator or slip ring,
characterized by
that the signal wire (122, 124) is fixed in position via a (second) recess (130) extending from a side surface (128) of the carbon brush (110). Carbon brush according to at least claim 8,
characterized by
that the signaling wire (122) is rammed into the first recess (116) via the second recess, such as bore (130), starting from the side surface (128), or is fixed in position via a fastening element, such as a screw, passing through the second recess (130). Carbon brush according to at least one of the preceding claims,
characterized by
that the cross section of the second recess (130) is larger than that of the first recess (116), preferably corresponds to 1.5 times the cross section of the first recess (116).

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