EP1968161B1 - System for contacting an electric conductor containing aluminium - Google Patents

Description

The invention relates to an arrangement for contacting an aluminum-containing electrical conductor, consisting of a fixed around the conductor herumgenegenden, metallic contact element to which at least one secondary electrical conductor is connected ( DE 198 21 630 C1 ).

Such an arrangement is used for example in the automotive and aircraft technology. The aluminum-containing conductors used therein are either made entirely of aluminum or an aluminum alloy, or they are aluminum wires surrounded by a copper sheath, which are known as copper-clad aluminum wires. A significant advantage of such electrical conductors, which may be embodied as solid conductors or as stranded conductors with a larger number of wires stranded together, is their lower weight compared to copper.

The lower electrical conductivity of aluminum over copper is of minor importance for most applications. However, problems arise when attaching contact elements to the conductors, since aluminum begins to flow under pressure, as is generated by a contact element pressed onto a conductor. This can lead after some time to a relaxation of the connection between the contact element and conductor, with correspondingly increased contact resistance. In extreme cases, the electrically conductive connection between the contact element and conductor can be completely interrupted. In addition, in a case of use unavoidable heating of the junction between the conductor and the usually made of copper contact element due to the different thermal expansion coefficients of aluminum and copper in addition a relaxation of the Contact element can occur. The change in dimensions within a contact connection between the conductor and the contact element occurring due to the described effects is in the range of a few μm. Despite these very small changes in dimensions, however, it can come to the described contact problems.

From the US 2,166,458 A goes out a connecting element for two electrical conductors. It consists of two elongated housings with conically narrowed ends, in which tapered clamping bodies are attached. Each of the two conductors is fixed in one of the housing by two such clamp body, which abut in mounting position with their outer surfaces on the respective housing. The mutually facing clamping body of the two housings are connected by a cylindrical bolt.

In the known arrangement according to the above-mentioned DE 198 21 630 C1 the conductor is constructed as a stranded conductor made of copper-clad aluminum wires. The fixed by crimping on the conductor contact element has, relative to the enclosed conductor, either in the axial direction extending slots or it is wavy. Thermal expansion stresses occurring during extreme temperature fluctuations are thereby to be compensated elastically.

The invention has for its object to make the initially described arrangement so that the fixed connection between the contact element and the conductor is ensured in the long term.

• daß das Kontaktelement aus zwei in Montageposition um den Leiter herum angeordneten und an demselben anliegenden Klemmkeilen mit einer konisch verlaufenden Außenfläche und aus zwei, je einen Klemmkeil umschließenden Klemmhülsen mit einer konisch verlaufenden Innenfläche besteht, die jeweils an der Außenfläche eines Klemmkeils anliegt, wobei die Klemmkeile mit entgegengesetzt gerichtetem Verlauf ihrer konischen Außenflächen, die kleineren Stirnflächen einander zugewandt in Achsrichtung des Leiters nebeneinander liegen, und
• daß zwischen den beiden Klemmhülsen mindestens ein in Achsrichtung des Leiters wirkendes Federelement angebracht ist.

This object is achieved according to the invention characterized

• in that the contact element consists of two clamping wedges arranged around the conductor in the assembly position and having a conically extending outer surface and two clamping sleeves each enclosing a clamping wedge with a conically extending inner surface which rests against the outer surface of a clamping wedge, wherein the clamping wedges with oppositely directed course of their conical outer surfaces, the smaller faces facing each other in the axial direction of the conductor next to each other, and
• that between the two clamping sleeves at least one acting in the axial direction of the conductor spring element is mounted.

The contact element of this arrangement is easy to mount by sliding on the electrical conductor. In this assembly, the spring element is compressed as much as possible by axial pressure, whereby it is simultaneously biased for its subsequent work function. As soon as the contact element is in its mounting position on the ladder, the spring element is relieved. It pushes then the two clamping sleeves in the axial direction apart, so that they lay firmly around a respective clamping wedge and thereby press the same to the head. This pressure is constantly maintained, even if the aluminum of the conductor flows and the same thereby reduces its diameter. The clamping wedges are also constantly tracked by the spring element for fixed contact with the conductor when different variations of conductor and contact element occur due to temperature fluctuations. By acting in the axial direction of the spring element thus the clamping sleeves are always applied so that they compress the respective clamping wedge and thus press firmly against the head.

In a preferred embodiment, the inner surfaces of the clamping wedges are made slightly tapered, with the advantage that the slopes of the inner surface and outer surface of the clamping wedges extend with opposite pitch. The thus furthest projecting edge of the clamping wedges is thereby pressed deeper into the conductor. It can also be broken by an oxide layer lying around the conductor. This is especially true when this edge of the clamping wedges is sharp-edged.

An embodiment of the subject invention is shown in the drawings.

• Fig. 1 das Ende eines Leiters der Anordnung nach der Erfindung mit schematisch angedeutetem Kontaktelement.
• Fig. 2 und 3 das Kontaktelement in zwei unterschiedlichen Positionen in vergrößerter Darstellung.
• Fig. 4 und 6 Seitenansichten eines zum Kontaktelement gehörenden Klemmkeils.
• Fig. 5 einen Schnitt durch Fig. 4 längs der Linien V-V.
• Fig. 7 einen Schnitt durch Fig. 6 längs der Linie VII- VII.
• Fig. 8 schematisch ein ergänztes Kontaktelement.

Show it:

• Fig. 1 the end of a conductor of the arrangement according to the invention with a schematically indicated contact element.
• FIGS. 2 and 3 the contact element in two different positions in an enlarged view.
• 4 and 6 Side views of a contact element belonging to the clamping wedge.
• Fig. 5 a cut through Fig. 4 along the lines VV.
• Fig. 7 a cut through Fig. 6 along the line VII-VII.
• Fig. 8 schematically a supplemented contact element.

In Fig. 1 the end of a conductor 1 freed from its insulation 2 is shown, which is constructed from a multiplicity of wires stranded together. The wires can be made of aluminum or an aluminum alloy or copper-plated Be executed aluminum wires. It can also be a solid conductor of the same materials used. At the end of the conductor 1, an electrical contact element K is to be attached, which in Fig. 1 only schematically indicated. At least one secondary conductor 3 is connected to the contact element K. It goes in an enlarged view of the FIGS. 2 and 3 out.

The contact element K consists of two clamping wedges 4 and 5, whose radial dimensions are variable, and of two surrounding same clamping sleeves 6 and 7. Between the clamping sleeves 6 and 7, at least one acting in the axial direction of the spring element 8 is attached. The spring element 8 consists in a preferred embodiment of at least one wave-shaped ring made of spring steel. But it can also be arranged as a spring element 8 distributed in the circumferential direction between the clamping sleeves 6 and 7 two or more springs. The clamping wedges 4 and 5 are in mounting position on the conductor 1, as it is in the FIGS. 2 and 3 is shown. They have conical outer surfaces, while the clamping sleeves 6 and 7 have corresponding conical inner surfaces, with which they bear against the outer surfaces of the clamping wedges 4 and 5.

The clamping wedges 4 and 5 are in the mounting position next to or behind each other on the conductor 1, with opposite course of their conical outer surfaces, so that their smaller faces are facing each other. The voltage applied to the outer surfaces of the clamping wedges 4 and 5 clamping sleeves 6 and 7 press in the radial direction to the same, when the clamping sleeves 6 and 7, an axial force in the direction of the arrows 9 and 10 is exercised. Such a force is generated by the spring element 8.

According to the 4 and 5 have the clamping wedges 4 and 5 at least one continuous axial slot 11 so that they can be compressed in the radial direction and pressed against the conductor 1. In a preferred embodiment, each clamping wedge 4 or 5 according to the 6 and 7 of two sections 12 and 13, which are separated by axially extending gaps 14 and 15 from each other. Each of the sections 12 and 13 extends for example over an angle of 170 °.

The inner surface or inner surfaces of the clamping wedges 4 and 5 or their sections 12 and 13 may be cylindrical throughout or have a partially cylindrical shape. But they can also be designed slightly conical, as it is for the clamping wedge 5 in the FIGS. 2 and 3 is drawn. The slope of these conical inner surfaces is advantageously opposite to the slope of the outer surfaces. The furthest in the direction of the conductor 1 projecting edge of the clamping wedges 4 and 5 is then pressed into the mounting position deeper into the conductor 1. In this case, an oxide layer surrounding the conductor 1 can be broken, in particular if this edge is made sharp-edged.

The clamping wedges 4 and 5 consist of a compatible with the material of the conductor 1, highly electrically conductive metal, such as a mechanically stable aluminum alloy. The clamping sleeves 6 and 7 may be made of the same material as the clamping wedges 4 and 5. But it can also be used another metal.

The continuing conductor 3 is preferably connected to one of the clamping wedges 4 or 5 electrically conductive. For this purpose, for example, the clamping wedge 5 have on its outer surface a corresponding recess for receiving the conductor 3. The continuing conductor 3 can also be connected to one of the clamping sleeves 6 or 7 electrically conductive.

All parts of the contact element K can be accommodated captive in a mountable or divisible housing 16 made of plastic or metal, as it is in Fig. 8 is indicated schematically.

To mount the contact element K to a conductor 1, the same is pushed onto the end freed from its insulation 2 until it has an in Fig. 2 achieved working position has reached. In this case, the spring element 8 is compressed by axial pressure on the clamping sleeves 6 and 7 as much as possible, so that the clamping wedges 4 and 5 are relieved during assembly of the contact element K.

When the contact element K assumes its working position, the pressure on the clamping sleeves 6 and 7 is released, so that the spring element 8 presses the same in the direction of the arrows 9 and 10. The clamping sleeves 6 and 7 are thereby pressed against the outer surfaces of the clamping wedges 4 and 5, which in turn are pressed firmly against the conductor 1 and optionally penetrate into the surface thereof.

In this way, the clamping wedges 4 and 5 are constantly pressed against the conductor 1, even if the diameter is slightly reduced, for example, by flowing the aluminum under pressure or by different extensions of conductor 1 and contact element K with temperature changes.

Fig. 3 shows in this sense an opposite Fig. 2 nachgedrückte position of the clamping sleeves 6 and 7 on the clamping wedges 4 and 5 with a corresponding "extended" spring element 8. The displacement of the clamping sleeves 6 and 7 and the extension of the spring element 8 are shown greatly exaggerated for better understanding. Also, this displacement or extension is in the range of a few microns according to the above statements.

Claims (6)

1. A device for contacting of an aluminium containing electrical conductor (1), comprising a metallic contact element (K) which firmly surrounds the conductor (1) and to which an extending electrical conductor (3) is connected, characterized in

   - that the contact element (K) consists of two cones (4,5) with variable dimensions which are positioned around the conductor (1) and which have conical outer surfaces and of two collets (6,7) surrounding the cones (4,5), having conical inner surfaces, which in mounting position lie against the outer surfaces of the cones (4,5), wherein the cones (4,5) lie side by side seen in the axial direction of the conductor (1) with an opposite run of their conical surfaces and with their smaller endfaces facing each other, and

   - that between the two collets (6,7) at least one spring element (8) is mounted which acts in axial direction of the conductor (1).
2. A device according to claim 1, characterized in that each cone (4,5) comprises two partly elements (12,13), which are separated from each other by spaces (14,15) running in axial direction.
3. A device according to claim 1, characterized in that each cone (4,5) has one continuous slot (11) running in axial direction.
4. A device according to one of the claims 1 to 4, characterized in that the inner surface of the cones (4,5) has a slightly conical form.
5. A device according to the claims 1 to 4, characterized in that the extending conductor (3) is fastened electrically conducting to one cone (4,5).
6. A device according to one of the claims 1 to 4, characterized in that the extending conductor (3) is fastened electrically conducting to one collet (6,7).

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