Electrical connectors – With external conductor or cable embedded in insulative...
Reexamination Certificate
1998-10-27
2001-01-09
Nguyen, Khiem (Department: 2839)
Electrical connectors
With external conductor or cable embedded in insulative...
Reexamination Certificate
active
06171147
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The invention related to a coupling element for a single wire or multi-wire electrical cable and a method of producing the same. The coupling element comprises a contact support to which a protective body surrounding the cable connection is molded in such a way that a region of the surface of the contact support remains exposed. The exposed region has openings extending through the contact support and contacts that are conductively connected with a wire of the cable arranged in the openings.
2. Description of the Related Art
Coupling elements, which can include pin-type connectors as well as female receptacles, are generally used to connect multi-wire electrical cable in the automobile industry. Such connectors provide, for example, a connection between the anti-lock braking system (ABS) or the electrical braking system (EBS) of a trailer and the tractor. If the cables between the vehicles are exposed, then the coupling elements are exposed to dirt, splash water, shock and tensile loads. It is therefore advantageous to use a mechanically robust construction that protects against moisture and dirt.
The utility model DE 94 10 092 discloses a coupling element wherein a protective body is molded to the contact support holding the electrical contacts in place. The protective body surrounds the cable or at least the section of the cable in which the jacket has been removed to electrically connect to the contacts, and also the marginal edge of the jacket. The protective body thereby forms a mechanical protection for the contact support as well as a strain relief for the cable while simultaneously sealing the cable. The contacts have to remain free of the molding material in order to provide a reliable connection with close tolerances between the coupling element and a mating element.
The region of the contact support in which the contacts are arranged, has a predetermined shape and can comprise raised portions, recesses or guides to connect to and lock with the mating element. The edge region of the contact support is typically sealed by a circumferential seal that is arranged, for example, in a groove disposed on the front face of the contact support. During operation, the coupling element is engaged with a complementary mating element that closes the seal. With this arrangement, dirt cannot accumulate in the contact region, and moisture is prevented from entering the coupling element along the contacts. Although it would be possible to seal only the individual contacts against the liquid molding material, it is preferred to keep the entire region near the seal and the contacts free of molding material to ensure a precise fit with the mating element.
It is difficult to seal the openings of the contact support in the area of the contacts. The contacts are typically inserted into and secured in the openings with a locking element. The contacts frequently have recesses or a shape that is not complementary to the cross-section of the opening. Consequently, the seal is not tight. To prevent the molding material from penetrating the openings when the protective body is formed, the DE-GM 94 10 092 proposes to hermetically seal the openings individually with separate sealing elements. Alternatively or in addition, a hot melt adhesive can also be used to form the seal.
Disadvantageously, however, sealing the openings is very labor intensive, with the costs increasing for multi-wire cables according to the number of wires. Also, the fabrication of the protective body of conventional couplings requires a comparatively large amount of molding material which raises the weight and the production costs.
SUMMARY OF THE INVENTION
With the foregoing in mind, it is an object of the invention to develop a coupling element with a molded protective body that can be fabricated at low cost.
In a primary aspect of the invention, a common cover is provided for the openings. The cover fits tightly against the contact support and extends over the openings of the contact support. The cover thereby prevents liquid molding material that after hardening forms the protective body, from gaining entry. The contacts with the attached wires are preferably inserted from the rear and thereby completely recessed. Moreover, the cover has to include a passage for the cable. The cable jacket fits tightly against the circumferential edges of the passage, and the cable is divided into the individual wires that are connected to the contacts, only inside the cover. Since the cable jacket has only one seal, the coupling element can be more easily manufactured, in particular for multi-wire cables, since not every wire has to be individually sealed.
The protective body is manufactured by injection molding it around the cover and surrounds the cover completely or at least partially. The protective body also surrounds the cable in the region of the passage. A portion of the contact support is surrounded by the protective body or at least borders the protective body. By using a suitable molding tool, a region of the surface of the contact support can be kept free of the molding material. Sometimes, the exposed region includes only the openings and therefore includes several parts; preferably, however, the exposed region is contiguous.
The contact support is made of a relatively rigid insulating material, e.g. a plastic such as polyamide, to provide a tight-fitting, reliable and mechanically strong connection with a mating element of the coupling element. The protective body, however, is preferably made of a relatively soft plastic, e.g. a thermoplastic elastomer (TPE), and forms a protective shock-absorber for the contact support and the cover. Moreover, a soft protective body adheres better to a flexible cable that is frequently subjected to tensile and bending stress. The cable jacket is also made of a relatively soft material, such as polyurethane, e.g. thermoplastic Elastolan.
Advantageously, the proposed coupling element is mechanically strong and provides a reliable strain relief and water seal of the cable connection. The coupling element can also be manufactured at significantly lower costs than conventional coupling elements. The empty space remaining inside the coupling element under the cover reduces the weight and the material costs even further.
The boundary surface between the protective body and the cover is frequently significantly larger than the boundary surface between the protective cover and the contact support. This improves the adhesion between the cover and the protective body forming the strain relief of the cable. However, the force to the element mating with the coupling element is transmitted exclusively through the contact support. The protective body can be prevented from separating when the coupling is subjected to a mechanical load by locking the contact support with the cover together, i.e. by providing a rigid connection between the contact support and the cover.
Advantageously, the connection is of the interlocking type. Suitable components are latching elements, such as raised portions or barbs, disposed on the contact support or the cover and engaging a recess or a projection of the respective other component. With a sufficiently resilient material, the resilient restoring force produced by the deformation of the components can provide adequate latching. The contact support can be connected reliably, easily and fast by attaching or inserting the cover. This connection cannot be disengaged after the protective body is molded. The protective body can also provide the latching connection by catching behind sections of the contact support and the cover.
Alternatively or in addition, a locking connection can be provided by carefully matching the materials for the contact support, the cover and the protective body. These materials then adhere to each other when the protective body is molded. For example, the materials can react with each other chemically or can melt together near the surface.
To reliably seal against the pressurized molding material of the
Jakob Thomas
Nachbauer Otto
Alcatel
Dugerne J. F.
Nguyen Khiem
Ware Fressola Van der Sluys & Adolphson LLP
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