Patent Application
20170229793
The invention relates in a first aspect to a heavy load plug connector as claimed in the preamble of the independent main claim 1.
The invention relates in a second aspect to a method for producing a crimp contact as claimed in the preamble of the independent coordinate claim 9.
The invention relates in a third aspect to a method for using a crimp contact as claimed in the preamble of the independent coordinate claim 14.
Plug connectors and contacts of this type are used in order to transfer between electrical conductors an electrical current having current strengths of by way of example 500 to 650 A.
It is known from the prior art to use both copper wires as well as aluminum wires so as to transfer electrical energy in particular in the high current range. By way of example, at that time in the GDR era aluminum was predominantly used for this purpose as an available raw material. This most often occurred in the form of relatively rigid individual conductors so that even nowadays energy supply conductors of this type are found in the new federal states. Conversely, in the old federal states in the past stranded conductors that are embodied from copper were predominantly used.
Owing to the current prices of copper and the resources of copper that are only available in limited supply and furthermore also owing to the clearly reduced specific weight (AL: 2.73 Kg/dm3; CU: 8.9 Kg/dm3) in many areas nowadays aluminum is increasingly used in many fields as a material for electrical high current transfer lines. It is preferred that the more flexible, in other words less rigid, stranded conductors are used. The current transfer can occur both above ground for example in wind power installations and also in the railway industry but also in the case of below ground energy distribution for example in the form of ground cables as a component of a larger current distribution network. The somewhat lower specific conductivity value of aluminum and the accordingly larger cable cross section that is required as a result of using said aluminum are accepted so as to achieve the above mentioned advantages.
The increasing use of aluminum cables in wind power installations is mentioned in the publication WO 2013 174 581 A1. Furthermore, the use of electrical connectors for electrically connecting various cables is described. The use of crimp connectors and screw connectors is mentioned. In order to avoid the disadvantages as a result of oxidation at the transition of the aluminum stranded wires to the connecting piece, it is proposed to weld the cable to the connecting surfaces of the connecting piece, for example by means of friction welding.
Furthermore, it is mentioned that the connection between the aluminum cable and the connecting piece can be performed by means of friction welding, rotational friction welding, ultrasonic welding or resistance welding. The connecting piece can be embodied from copper. In an alternative thereto, it is disclosed that the connecting piece is likewise embodied from aluminum in order to avoid transition resistances or contact corrosion at the transitions between the aluminum cable and the contact piece. Moreover, a tin plating or a tin plating and nickel plating of the surface of the connecting pieces is proposed.
The publication DE 10 2013 105 669 A1 likewise discloses connecting electrical connectors to a stranded conductor by means of resistance welding.
The publication EP 1 032 077 A2 proposes in this context connecting a stranded conductor of aluminum by means of frictional welding to a contact part that is embodied from copper.
The publication EP 2 621 022 A1 discloses a cable lug for connecting a current-conducting element to an aluminum cable, wherein a first section of an associated pipe comprises on an inner face an aluminum coating and on an outer face a copper coating.
EP 2 662 934 A2 proposes the use of a connecting cap embodied from aluminum or from an aluminum alloy. This connecting cap is pressed onto the aluminum conductor and is welded to the contact part that is embodied from copper or a copper alloy.
Fundamentally, it is unfortunately particularly complex to assemble these construction forms in which in other words the stranded conductor is directly or indirectly welded onto the contact and the assembly procedure cannot be implemented on-site without corresponding devices so that it is not possible to assemble these construction forms in the field.
DE 11 2011 103 392 T5 discloses a crimp connection that is embodied from two different metal materials, for example copper and aluminum. The connecting region of these two materials is covered with a synthetic material molded part so as to avoid corrosion.
The publication EP 2 579 390 A1 likewise discloses an aluminum-copper terminal that comprises an aluminum contact part and a copper connecting part that are welded to one another, wherein the connecting region is protected by means of attaching a primary seal that is protected against electrical corrosion for example by means of injection molding using a specific thermoplastic, wherein the stranded wire is welded to the contacting part.
Consequently, in both these two latter mentioned publications, it is proposed to seal the affected transition region using a sealing arrangement, by way of example by means of injection molding using a specific thermoplastic. However, on the one hand this procedure is complex, and on the other hand such a sealing arrangement generally only has a limited serviceable life. A connector that is embodied in this manner is not suitable as a contact element for a plug connector.
The above-mentioned publications furthermore relate to connectors with which a supply cable is permanently connected to a current rail or to another cable so as to provide a fixed installation. This installation is in other words assembled once and is fundamentally not provided for the purpose of being altered numerous times.
In contrast to this, in the prior art electrical heavy load plug connectors that comprise crimp contacts are also disclosed by way of example in the publication EP 892 462 B1 and their cable connecting technology is as a consequence considerably simpler.
However, even in this case the problem remains that the stranded wires of the aluminum conductor owing to their oxidization comprise a poor so-called “cross-conductivity” (in other words the conductivity between the individual stranded wires perpendicular to the extent of the cable), which likewise increases the transition resistance to the connector contact in the case of all the described arrangements.
Furthermore, there is the further problem that aluminum oxidizes easily and furthermore connects poorly to other metals such as for example copper or brass. In particular, this applies owing to its large surface for aluminum stranded conductors. In the transition region between aluminum and by way of example copper, so-called “electrical corrosion” occurs in particular in the event of being energized with high current strengths for a long period of time and in the event of a simultaneous influence of oxygen and thereby a layer that comprises a fundamentally higher specific resistance than each of the metals involved is produced. As a result of this high resistance, an intense heating can occur during operation owing to the high current strengths and as a result of said heating this transition resistance additionally increases in the form of an interaction. This development of heat can additionally lead to further consequential damage, by way of example to a synthetic material insulation.
By way of example in the railway industry but also in many other industries, there are applications that require frequent alteration of the electrical high current cabling. Consequently, there exists in the prior art a requirement for high current connectors that can be arranged in a flexible manner and that can preferably be assembled in the field or at least can be assembled with as little outlay as possible.
The object of the invention consequently resides in providing an electrical connector that on the one hand renders it possible to connect an aluminum stranded conductor in a comparatively simple manner and that on the other hand renders possible as flexible an arrangement as possible and that furthermore even in the case of a high current strength acting over a long period of time comprises a sustainably good electrical conductivity.
The object of the invention is achieved in a first aspect with a heavy load plug connector of the type mentioned in the introduction by virtue of the features of the characterizing part of the independent main claim 1.
In a second aspect, the object is achieved using a method of production of the type mentioned in the introduction by virtue of the features of the characterizing part of the independent coordinate claim 9.
In a third aspect, the object is achieved with a method of application of the type mentioned in the introduction by virtue of the features of the characterizing part of the independent coordinate claim 14.
Advantageous embodiments of the invention are disclosed in the dependent claims.
The invention in accordance with the first aspect is a heavy load plug connector having at least one crimp contact, wherein the crimp contact comprises a crimp region that is embodied from aluminum or an aluminum alloy, and a contact region that adjoins said crimp region and is embodied from copper or from a copper alloy, wherein the contact region can be embodied as a pin-shaped or socket-shaped manner. Consequently, an aluminum stranded conductor having a crimp region can be crimped without a so-called “electrical corrosion” consequently occurring.
The transition from copper material to the aluminum material is relocated for this purpose in accordance with the invention in the crimp contact. This is rendered possible in that the crimp region is welded to the contact region. In particular, this connection is produced when producing the crimp contact by means of a frictional welding procedure.
The crimp contact can in other words be a contact pin that is capable of conducting high currents or a contact socket that is capable of conducting high currents. At least one contact pin of this type and/or one contact socket are inserted into an insulating body and together with said insulating body form a component of the heavy load plug connector.
It is particularly advantageous that the crimp contact is at least in regions embodied in a rotationally symmetrical manner or comprises at least one or multiple regions having a cylindrical shape or at least a rotationally symmetrical outer contour because said crimp contact can consequently be arranged in a positive-locking manner in the through-going holes or corresponding likewise rotationally symmetrical through-going openings of the insulating body.
Furthermore, it is advantageous in accordance with the second aspect during production to use aluminum owing to its ability to deform easily as a material for the crimp region of the crimp contact. This is particularly advantageous for crimping an aluminum conductor, in particular an aluminum stranded conductor because electrical corrosion and in intermetallic phase does not occur on the affected region despite unavoidable contact with oxygen.
The crimp region comprises a hollow chamber having a cable insertion opening for receiving the aluminum stranded conductor.
Furthermore, an additional through-going hole can be subsequently drilled in the crimp contact to the hollow chamber and an inner thread can be cut in said through-going opening.
In accordance with the third aspect of the invention, it is possible by way of said inner thread for a spike, which comprises an outer thread that is tailored to suit said inner thread, and also a tip that is connected to said outer thread to be screwed using its tip forwards into the hollow chamber, preferably in the direction of the cable insertion opening, in other words counter to the direction of insertion of the stranded conductor.
As a consequence, the stranded wires of the previously inserted aluminum stranded conductor are pressed from the interior against the crimp region. Advantageously, the crimp contact comprises an additional inner thread within its crimp region. The stranded conductor is then pressed from the interior against said additional inner thread, wherein the additional inner thread holds the stranded wires by means of the increased frictional force. Furthermore, the oxide layer of the aluminum stranded wires is broken open. As a consequence and by means of the pressure against one another, the cross conductivity of the stranded conductor increases. Consequently, the transition resistance between the stranded conductor and the crimp contact decreases. The conductivity is also sustainably increased after crimping by means of using the spike, in particular if the spike is preferably embodied from aluminum or also from another electrically conductive material, by way of example a copper alloy and as a consequence the contact surface of the crimp contact increases with respect to the stranded conductor.
During production, it is advantageous if the inner radius of the cylindrical hollow chamber is greater than the theoretical inner radius of the additional inner thread that is cut so that the additional inner thread that protrudes into the hollow chamber is flattened off. This is particularly advantageous because as a consequence on the one hand two desired effects of the additional thread remain intact, namely 1.) that the oxide layer of the aluminum stranded wires is broken open, and 2.) that the stranded conductor is held in the hollow chamber using a particularly effective frictional effect against the direction of insertion, but that on the other hand 3.) the stranded wires are not damaged. Thirdly, it is particularly advantageous if the actual depth of the thread that has been flattened off is smaller than the diameter of the stranded wires so that the thread cannot cut through said stranded wires.
Owing to its stability and good electrical conductivity it is advantageous to use copper as a material for the contact region. In one advantageous embodiment, the contact region is additionally coated at least in part, by way of example silver-plated or gold-plated, and thus permanently protected against corrosion. Furthermore, as a consequence a permanent low ohmic plug connection to other copper contacts and furthermore to corresponding copper conductors is advantageously also possible since the problematic transition between copper and aluminum is relocated in accordance with the invention into the interior of the crimp contact.
It is particularly advantageous that the crimp region that is embodied from aluminum is connected to the contact region that is embodied from copper by means of frictional welding because in this manner electrical corrosion is prevented from occurring. Finally, the contact surface is thus located in the interior of the contact and in this manner does not come into contact with oxygen. As a consequence, a good conductivity is also sustainable, in other words is also ensured over a long period of time.
Furthermore, the welding procedure in particular the frictional welding provides a particularly stable connection so that the crimp contact is also mechanically stable.
During production, in accordance with the second aspect of the invention it is possible to use cylindrical copper and aluminum blanks that are welded to one another in the axial direction, in particular by means of frictional welding. Initially, the rotational welding appears accordingly expedient for the frictional welding procedure. However, it is also advantageously possible to connect the crimp region to the contact region by means of vibration welding. In practice, a combination of rotational welding and vibration welding has proven particularly advantageous since in the case of pure rotational welding there is the disadvantage that the inner regions of the contact surface experience less friction than the outer regions so that the elements have had to comprise at least in the contact region a central so-called “blind hole”. However, during a particularly complex vibration welding procedure all regions experience the same frictional energy so that even the inner regions of the contact surface can be welded. In combination, the advantages of the two methods can expediently complement one another.
The contact region can be embodied as a pin contact or socket contact by means of a turning and drilling procedure and the hollow chamber can be drilled with the cable insertion opening into the crimp region. It is preferred that the additional inner thread that is used to increase the frictional force acting upon the stranded conductor can be cut in the hollow chamber.
An exemplary embodiment of the invention is illustrated in the drawings and is further explained hereinunder.
In the drawings:
The figures include in part simplified, schematic illustrations. In part, identical reference numerals are used for identical but however where appropriate non-identical elements. Various views of identical elements could be scaled differently.
It is possible to drill a first hollow chamber 111 into the first crimp region 11 that is embodied from aluminum. As a consequence, the first crimp region 11 comprises on its free-standing end adjacent to the hollow chamber a first cable insertion opening 110.
A hollow chamber 211 can furthermore be drilled into the second crimp region 21 that is embodied from aluminum. As a consequence, the second crimp region 21 comprises a second cable insertion opening 210 on its free-standing end adjoining the second hollow chamber 211.
Furthermore, the first crimp region 11 comprises in this modified embodiment in its first hollow chamber 111 a first additional inner thread 112 that is cut from the interior into the first crimp region 11 during production of the pin contact 1. This first additional inner thread 112 is used for the purpose of holding a stranded conductor, which is inserted into the first hollow chamber 111, in said chamber by means of an increased frictional force, even if the spike 113 is screwed into the first hollow chamber 111 in the direction of the first cable insertion opening 110, in other words against the direction of insertion of the stranded conductor.
In other words, during production only the outer part of the theoretical inner thread is cut in the first crimp region 11 and the additional inner thread 112 that actually exists and is formed as a result consequently comprises a form that is a particularly flattened off form.
Furthermore, the second crimp region 21 comprises in the second hollow chamber 211 a second additional inner thread 212 that is cut during production from the interior into the crimp region 21 of the socket contact 2. This second additional thread 212 is used for the purpose of holding a stranded conductor that is inserted into the second hollow chamber 211 in said hollow chamber by means of an increased frictional force even if the spike 213 is screwed into the second hollow chamber 211 in the direction of the second cable insertion opening 210, in other words against the direction of insertion of the stranded conductor.
An advantageous embodiment of the second additional inner thread 212 is illustrated in an enlarged view in
In other words, during production only the outer part of the theoretical inner thread is cut in the second crimp region 21 and the additional inner thread 212 that actually exists and is formed as a result consequently comprises a particularly flattened off form.
Furthermore, an insulating body 3 is illustrated that is provided so as to receive the pin contact 1. This insulating body 3 can be fastened for its part by way of fastening elements 31 in the plug connector housing 4.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2014 112 701.3 | Sep 2014 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/DE2015/100330 | 8/5/2015 | WO | 00 |
