Electricity: conductors and insulators – Conduits – cables or conductors – Combined
Reexamination Certificate
1999-10-05
2001-06-12
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Conduits, cables or conductors
Combined
C174S07700S
Reexamination Certificate
active
06246000
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an electrical contact element.
BACKGROUND OF THE INVENTION
Sensing elements that are exposed to high temperatures and vibration loads, such as those that can occur, for example, within the exhaust system of motor vehicles, are known. The electrical supply leads to such sensing elements are exposed to considerable temperature stresses, that conventional cable insulation cannot withstand. In particular, the connecting points of the sensing elements to the electrical supply leads, and their insulating layers, must be effectively shielded against excessive temperatures. In lambda probes, for example, heat-resistant metal-sheathed lines, which must have a certain minimum length are usually used. Only beyond a specific distance from the heat-stressed measurement location can conventional cables take over the electrical connection to a downstream analysis unit.
The connecting point between the heat-resistant metal-sheathed line and the conventional cable line must, however, be configured so as to be completely sealed against external influences. Also any excessive length of the metal-sheathed line is problematic, and creates the risk of vibration breakage. The metal-sheathed line must therefore be as short as possible because of the vibration loads that occur, so that the requirements for the connecting point comprise not only sealing against environmental influences and moisture, but also the greatest possible temperature resistance.
Connections between a rigid metal-sheathed line and flexible cable lines that are injection-coated with plastic. Since, however, it is generally not possible with an injection-coated plastic sheath of this kind to create sealed connections between the metal-sheathed line and the insulated cable lines, additional measures, for example elastomer seals, are necessary. The volume of the connection and its mass and thus the moment of inertia increase as a result of these measures. This has a disadvantageous effect on the vibration resistance of the sheathed lines, thus subjecting them to a risk of breakage.
SUMMARY OF THE INVENTION
The object of the present invention is to create a sealed and temperature-resistant connection between a metal-sheathed line and flexible cable lines that has the lowest possible mass.
By way of the largely prefabricated contact elements, it is possible to create, in a rapid and economical manner, lightweight, temperature-resistant, and vibration-resistant electrical connections from heat-stressed sensing elements to wiring harnesses. Conventional connecting techniques such as crimping and snap-locking are used in this context. Because the electrical contacts are very well insulated from one another, there is no risk of shunts or short-circuits. Because of the geometrical configuration of the contact housing with centering aids and insertion aids, incorrect assembly is almost ruled out. Automatic assembly, for example using assembly robots, is thereby reliably guaranteed. The subsequent laser welding of the electrical contacts and an enveloping thin protective metal sleeve also permits rapid automatic assembly. A robust, durable connection that is secured against breakage and vibration, and shielded from heat and any type of environmental influence is also ensured. An elastomer seal ensures sealed encapsulation of the connecting element that is also resistant to temperatures exceeding 200° C. Lastly, the extremely compact and lightweight design, which minimizes the metal-sheathed line's susceptibility to vibration or vibration-induced breakage, is particularly advantageous.
The contact housing of the contact element must be able to withstand relatively high temperatures, and for that purpose can be made, for example, from a thermosetting plastic or a ceramic material. These materials also have the advantages of high stiffness, high mechanical load-carrying capacity, and relatively unrestricted three-dimensional design freedom. The mechanical properties can be further improved by way of fiber reinforcements. The contour of the contact element can be cylindrical, but because of the unrestricted shaping freedom using the molding or injection molding method, it can also be of any other desired configuration, depending on the desired installation location or additional anchoring or immobilization.
For a stable and vibration-free mechanical and electrical connection between the electrical lines guided in the metal-sheathed line and the flexible cable lines leading to an analysis unit, the latter are joined to one another inside the contact housing by laser welding. As compared to conventional plug-in contacts, these connections exhibit much greater long-term durability and thus better service life. Laser welding of the metal-sheathed line to a metal sleeve enclosing the contact housing practically rules out any penetration of moisture or other substances that might impair electrical insulation, even during a long operating period.
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Bareiss Alexander
Eisenschmid Heinz
Wehrmann Johann
Kenyon & Kenyon
Mayo III William H.
Reichard Dean A.
Robert & Bosch GmbH
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