Patent Application
20110147079
This application claims the benefit of German Patent Application No. 10 2009 060 419.7 filed on Dec. 22, 2009, which is hereby incorporated by reference.
The present invention relates to a tension-resistant electrical conductor, comprising a central core wire and at least two wire layers arranged over the core wire.
A conductor is described, for example, in EP 2096645 A1, where the desired tensile strength is achieved by a layer of steel wires, which is arranged over a core wire, which is made of copper. Such a conductor, having suitable insulation, is notably intended for use in wiring or sensor lines in the automotive industry, where small cross-sections, and consequently advantageous bending properties, as well as high flexibility and high tensile strength, are important.
However, particularly in the field of sensor lines that serve, for example, as supply lines for so-called lambda sensors in the catalytic converters of motor vehicles, there is an increasing demand for these lines to be designed so they can be closed in a gas-tight manner at the ends thereof, for example, when a selected end of the line is finished with what is referred to as a crimp contact. If, to this end, after the conductor insulation has been removed, the conductor wires are pressed together by placing a contact sleeve around them, in a well-known manner, the known closed steel wire layer, which is arranged over the core wire, forms a supporting arch, which prevents all of the wires, including the core wire, from being pressed together. This results in channels, which run longitudinally within the conductors and, under the effect of moisture from the outside, may result in corrosion of the conductor, and in reduced flexibility caused by the closed steel wire layer.
It is therefore an object of the invention to configure the conductor of an electrical cable, or of a line, having small external dimensions, so that it is highly flexible, yet resistant to tension, and so that it can be closed in a gas-tight manner without difficulty by a simple crimp connection, which is considered to be particularly efficient in current connection technology.
This object is achieved according to the invention by arranging a first inner wire layer comprising, in the circumferential direction, an alternating sequence of copper wires and wires having higher tensile strength, over a central core wire made of copper, or a copper alloy, and producing a second, or any further, outer wire layer exclusively from copper wires. With a conventional arrangement of six wires in the first wire layer of a so-called stranded conductor, this means that, as differs from known conductors, the wires having greater tensile strength are arranged in a star shape in the conductor strand, and thus allow for greater flexibility, without detracting from the required tensile strength. Where special value is increasingly set on a reduced weight, as is the case in aviation, the electrical conductors configured according to the invention are of particular importance.
Another particular advantage of the invention is that, as a result of deformation of the softer copper wires when radial pressing force is applied from the circumference, all hollow spaces in the conductor are filled in, all the way to the core wire, whereby, for example, a stripped, which is to say bared, conductor end can be closed in a gas-tight manner. According to the invention, subsequent to compacting the conductor, the wires having greater tensile strength are substantially embedded in a copper matrix. In addition to the gas tightness of the conductor end, it is also important that the copper matrix provides an extremely good and lasting electrical-contact connection with the surrounding connecting part, such as a crimp contact. Such a conductor can therefore be particularly advantageously employed where there is a particular need for electrical supply cables or lines to provide flexibility, tensile strength, and corrosion resistance, while also providing reliable contact, such as in the automotive field, or in aeronautical engineering.
The wires having greater tensile strength can be, for example, high-alloyed copper wires, but in general, when carrying out the invention, steel wires will be employed, and particularly wires made of stainless steel, which exhibit even greater tensile strength and, in the case of stainless steel, are corrosion-resistant. A stranded conductor configured in this way demonstrates a tensile force of at least 200 N.
In a further aspect of the invention, the copper wire that is used as the core wire and the wires made of copper that are arranged in the individual wire layers may be bare copper wires, however it has proven to be particularly advantageous to employ nickel-plated, tin-plated, or silver-plated copper wires for the purpose of the invention.
Depending on the intended use, the electrical conductor according to the invention may comprise a wide variety of insulators over the outermost copper wire layer. For example, the insulator may comprise polyvinylchloride (PVC), polyethylene (PE), a rubber or silicone-rubber material, or a polyetherketone based polymer (PEK, PEEK, PEKK). If there is an elevated demand for corrosion resistance and resistance to corrosive media such as oils and greases, as in the case of automotive engineering, in a further aspect of the invention, the use of fluoropolymers will be more common as the insulating material for the electrical conductor. Such fluoropolymers may be polymers that deform under heat, such as perfluoroalkoxy copolymers (PFA), fluorinated ethylene propylene (FEP), ethylene tetrafluoroethylene (ETFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers (TFA/PFA) or similar fluoropolymers.
However, if the insulating material is to cover a broad temperature range, including both very low and very high temperatures, a fluoropolymer that cannot be deformed under heat will be employed according to the invention. This is a polytetrafluoroethylene (PTFE), or a polytetrafluoroethylene modified by additives, provided this modified polytetrafluoroethylene cannot be deformed under heat.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings, which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:
The invention will be described in more detail with reference to the exemplary embodiments shown in
If, as already indicated above, a crimp contact having a contact tab is to be attached to one or both ends of the cable 1, in order to electrically connect a load, a crimp barrel is placed around the stripped conductor end, which is to say the end that has been bared of the insulator 6, and the barrel is pressed together with the conductor end.
Ultimately, the design of the electrical conductor according to the invention results, for example, in a pre-assembly of wiring harnesses with crimp contacts of high and consistent quality, which allow for rapid wiring.
The invention is not limited to the exemplary embodiment, and thus is likewise not limited to the use of the cable 1 according to the invention in automotive engineering. Further usage possibilities include, for example, the aviation industry mentioned above, as well as the broad field of data transmission.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2009 060 419.7 | Dec 2009 | DE | national |
