Electrical connectors – Metallic connector or contact having movable or resilient... – Spring actuated or resilient securing part
Reexamination Certificate
2002-08-23
2004-08-10
Gilman, Alex (Department: 2833)
Electrical connectors
Metallic connector or contact having movable or resilient...
Spring actuated or resilient securing part
C439S816000, C439S840000
Reexamination Certificate
active
06773312
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is entitled to the benefit of and incorporates by reference essential subject matter disclosed in German Patent Application No. 101 43 200.3 filed on Sep. 4, 2001.
FIELD OF THE INVENTION
The present invention concerns an electrical pressure contact, including:
a housing sleeve with a contact facing end and an end facing away from the contact,
a contact pin axially slidably supported in the housing sleeve, which contact pin extends out of the contact facing end of the housing sleeve, is pushable into the housing sleeve against the biasing force of a biasing element arranged in the contact sleeve, and through whose conductive body the electrical contact is made,
a terminal piece for the fastening of an electrical supply conductor to the end of the housing sleeve facing away from the contact, and
a flexible electrical conductor arranged in the housing sleeve between the terminal piece and the contact pin.
BACKGROUND OF THE INVENTION
Electrical pressure contacts of this type serve, for example, to conduct current between elements which are movable relative to one another. Therefore the contact pin has a two-fold function: On one hand it can make a spring-loaded mechanical contact with an opposite contact movable relative to the housing sleeve. On the other hand, an electrical contact can be made through its current conducting body. Electrical pressure contacts of this type are used in large numbers, especially in railroad couplings.
In customary electrical pressure contacts of the above-mentioned kind, the flexible electric conductor is formed by strands, which are rigidly soldered to the contact pin and to the terminal piece. Generally, several strands are pleated and are so pre-twisted that they can accommodate a pushing of the contact pin into the housing sleeve without the strands becoming bucked, to avoid damage to the strands. Nevertheless, in customary electrical pressure contacts, as a result of a large number of contact reciprocations, the strands unfortunately often become damaged, especially broken. Moreover, the making of such electrical pressure contacts is relatively time consuming and expensive.
EP-O-435 408 B1 shows an electrical pressure contact intended to avoid these problems. In a case of this pressure contact, no stranded conductors are used. Instead of this, the contact pin is partially formed as a hollow cylinder whose wall is provided with several longitudinal slots, whereby wall sectors are achieved which are formed as springy, current conducting contact tongues. These contact tongues, on their inner sides, lie slidable on a current conducting housing sleeve, so that current can flow through the contact tongues and the housing sleeve to the terminal piece. The making of such a stranded conductor-free pressure contact is, however, similarly expensive.
DE-4-317 255 C2 shows an electrical pressure contact for completely-automatic or semi-automatic railroad vehicle coupling with a housing sleeve of plastic and a sliding sleeve slidably supported in the housing sleeve, which sliding sleeve transitions into a hollow formed contact pin. A metallic contact sleeve is insertable into this hollow contact pin from the outside, which metallic contact sleeve at its contact facing side carries a contact plate, and at its side facing away from the contact is crimped to a cable end. In this type of pressure contact, the contact pin therefore creates only a mechanical contact, while the electric contact has to be created through a conductor positioned in the interior of the contact pin. Such a construction requires therefore an increased number of construction components and a more expensive assembly, which increases the production costs.
SUMMARY OF THE INVENTION
The invention has as its object the provision of an electrical pressure contact of the previously mentioned kind, which is of simple construction, can be made economically, and which has a long service life, that is, can withstand an especially high number of contact reciprocations without damage.
This object is solved by way of an electrical pressure contact of the aforementioned kind in that the braided tubular conductor at its end facing the contact is clamped in a bore formed in the end of the contact pin facing away from the contact, and at its end facing away from the contact is clamped into an axial bore formed in the end of the terminal piece facing the contact.
Further, the respective sections of the contact pin and of the terminal piece into which the conductor ends are inserted in the bores, are pressed radially inwardly and with a pressure which is so measured that the braided tubular conductor on one hand is sufficiently clamped so that it cannot become loosened and provides a good electrical contact, and on the other hand that the braided tubular conductor is not damaged by the pressing. This type of fastening is called crimping.
By the direct crimping of the conductor with the contact pin and with the terminal piece, the construction of the electrical pressure contact of the invention is simple and its manufacture is economical. Especially, its manufacture is significantly less expensive than in the case of soldered connections.
In contrast to a pressure contact with soldered connections, the pressure contact of the invention has a higher service life. For one thing, with an overheating of a soldered pressure contact, the danger exists that the solder becomes plastic and the stranded conductor “unsolders itself”, that is, the connection becomes unmade. As another thing, in the case of a soldered stranded conductor, the danger of breakage is higher than in the case on a crimped stranded conductor. Among other things, that is because in the case of soldering solder can penetrate from the soldered location through the flexible conductor and stiffen the flexible conductor with the result that the flexible conductor is easily broken by the axial movement of the contact pin.
In a preferred embodiment the biasing mechanism is formed by a helical spring.
In a preferred embodiment, the flexible electrical conductor is formed by a braided tubular conductor. A braided tubular conductor having at least some degree of flexibility can fan out under axial loading and in this way can accommodate the axial loading without the strands of the stranded conductor becoming buckled and thereby broken. Since a braided tubular conductor is compressible in the axial direction, it can be simply arranged along the housing sleeve axis. This represents a large simplification in comparison to the stranded conductors used in customary pressure contacts, which for example are assembled with a given preliminary twisting between the contact pin and the terminal piece so that they upon axial loading lie together in loops. To make such a preliminary twisting, the contact pin must always be rotated in a given way relative to the terminal piece. This requires means for holding the contact pin in the rotated position. In the pressure contact of the invention with a braided tubular conductor such means are however not required, which benefits a simple construction of the pressure contact.
In an advantageous development, the flexible electrical conductor is a braided tubular conductor made of strands of copper. A braided tubular conductor can especially well accommodate an axial compression without thereby becoming damaged. A braided tubular conductor can therefore be designed relatively large while still providing a sufficient flexibility. That is, it can indude a large number of strands so that the electrical resistance of the pressure contact is lowered.
In a further preferred embodiment, the flexible electrical conductor is formed by the helical spring. This spring can in a way similar to the described stranded conductor be crimped to the contact pin and to the terminal piece. This leads to a yet simpler construction of the pressure contact and to a yet lower manufacturing cost. Moreover, such type of pressure contact is of a significantly higher service life because the danger of
Bauer Monika
Dost Robert
Kainz Andreas
Moskob Frank
Schumann Bernd
era-contact GmbH
Gilman Alex
McCormick Paulding & Huber LLP
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