Electrical connectors – Contact comprising cutter – Insulation cutter
Reexamination Certificate
1999-09-29
2001-12-04
Patel, Tulsidas (Department: 2839)
Electrical connectors
Contact comprising cutter
Insulation cutter
C439S164000, C439S404000
Reexamination Certificate
active
06325657
ABSTRACT:
BACKGROUND OF THE INVENTION
This application is based on and claims the benefit of German Patent Application No. 198 44 869.4. filed on Sep. 30, 1998.
The invention relates to a contact element for connecting a ribbon cable with circular conductors, whereby the contact element comprises a plurality of mutually insulated parallel conductor strips made of a conductive material, to the one end of which a circular conductor may be attached and the other end of which is provided with a surface to which a strand of the flat ribbon cable may be fixed through a material connection, as well as a rotary connector with such a contact element.
Interference-free power or signal transmission between parts of a device that are rotatable with respect to each other within a limited angular range is a problem frequently encountered. For example, a permanently secure power supply for triggering the airbag in the steering wheel of a motor vehicle is of decisive importance. Since sliding contacts, due to wear and fluctuating contact resistances, are unsuitable for this purpose, rotary connectors with ribbon cables have been developed to ensure a reliable connection.
The ribbon cable (hereinafter referred to as FBL) is disposed in the gap between two mutually rotatable housing parts of the rotary connector and fixed to both housing parts by its end faces. Preferred is a flat ribbon cable made of one or a plurality of flexible metal strips spaced at a distance from each other and embedded between two plastic strips. In the simplest case, the FBL extends helically like a clock spring within the gap. When the housing parts are rotated relative to each other, the diameter and the number of the turns changes as a function of the direction of rotation. Alternatively, the turns of the FBL extend along the radially inner and outer wall of the gap with opposite sense of rotation, whereby a reversal point is provided between the two cable sections. In this case, as the housing parts of the connector are rotated relative to each other, the cable is unwound from the one wall and taken up by the other wall. It is also known to dispose guide elements or elastic elements within the gap and to make the FBL from an elastic material to ensure reliable guidance as the housing parts are rotated relative to each other and to prevent damage.
Generally, the rotary connector is externally connected by circular conductors, i.e., wires or flexible leads with an at least approximately circular cross-section. Accordingly, a contact element is required for the electrical connection of the circular conductors and the strands of the ribbon cable. DE 41 19 769 A1 discloses a rotary connector with such a contact element. This contact element comprises several parallel mutually insulated metal strips that are connected to the strands of the FBL, for example by soldering or welding. The opposite ends of the conductor strips are made as plug contacts into which counter contacts connected with the circular conductors may be plugged. The disadvantage, however, is that this construction requires the prefabrication of the circular conductors with corresponding counter contacts, which is not only high in labor, but also requires tools for manufacturing and mounting the counter contacts. Furthermore, it increases the number of connecting points in the course of the cable and thus the risk of faulty contacts, particularly if the contacts are exposed to constant vibrations in a motor vehicle.
SUMMARY OF THE INVENTION
Against this background, the object of the invention was to develop a contact element for reliably connecting circular conductors with a ribbon cable, which is simple to manufacture and contact.
This object is attained by the invention in that a conductor strip has at least one pair of blades between which a circular conductor can be inserted under termination.
One basic idea of the invention is to attach the circular conductors directly to the contact element's conductor strips, which are preferably made of a metal. Insulation piercing terminals, into which the circular conductors are inserted, permit simple and rapid contacting. A suitable distance between blades ensures permanently reliable contact between the circular conductor and the conductor strip, whereby the use of an insertion tool permits a comparatively high clamping force. Since the circular conductor does not need to be stripped prior to insertion into an insulation piercing terminal, contacting is made significantly easier.
Depending on the desired alignment of the contact element or its conductor strips and the outgoing conductors, the blades may be arranged in the plane of the strips. It is preferred, however, to position the blades outside the plane of the strips, for example, perpendicularly thereto. Furthermore, two or several pairs of blades may be provided for contacting a circular conductor to ensure a permanently secure connection even in the case of vibrations and alternating loads such as those that occur, in particular, in a motor vehicle.
The connection between the contact element and the FBL is effected through the materials, whereby a conductor strip preferably has a level surface, e.g., a tongue, to which a strand of the FBL is fixed. Soldering or welding are particularly suitable, for example spot welding or ultrasonic welding. Advantageously, the width of this surface approximately corresponds to or slightly exceeds the width of the FBL strand. For the FBL, a flat conductor ribbon cable made of strip-shaped copper conductors laminated between two plastic foils or deposited onto a plastic foil is particularly suitable.
In a preferred embodiment of the invention, the conductor strips of the contact element are one-piece stampings to permit cost-effective production. Advantageously, the insulation piercing terminals are also formed during this stamping process. Individual areas of the conductor strip may be turned out, for example in the area of the insulation piercing terminals to obtain the desired arrangement of the outgoing circular conductors and the FBL. To fix the conductor strips of the contact element relative to each other, the conductor strips are connected by means of one or a plurality of insulating supports. The conductor strips are preferably fixed in a common support. As an alternative to the use of a prefabricated support made of one or several components, the conductor strips, after stamping, may be extrusion coated with liquid plastic, which hardens into the support.
The invention furthermore proposes that the conductor strips, prior to being fixed by the supports, be connected by at least one bridge. This simplifies the production of the contact element since only one part has to be handled whose conductor strips are attached to each other by one or several supports. This bridge is subsequently removed, e.g., by stamping. This requires that it be accessible from the outside after the conductor strips have been fixed within a support. The bridge may be disposed, for instance, in an area of the conductor strips protruding beyond a support.
The bridge is preferably integrated with the conductor strip to permit all conductors of the contact element to be produced together, for example in one stamping process. The bridge is advantageously arranged at the end of the conductor strip that is intended for the attachment of the ribbon conductor. This prevents the bridge from interfering with the formation of the insulation piercing terminals as well as any turnouts required in this area. The formation of the insulation piercing terminals frequently requires them to be formed from a strip section that is wider than the remaining parts of the conductor strip. The invention therefore proposes mutually to offset the insulation piercing terminals of adjacent conductor strips in longitudinal strip direction. Particularly if during formation of the strip, the area of the insulation piercing terminals is folded up from the plane of the strip, there is a wide variety of possible arrangements of the insulation piercing terminals, which are of
Hyeon Hae Moon
Nexans
Patel Tulsidas
Sughrue Mion Zinn Macpeak & Seas, PLLC
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