Primary cable of compressed conductor

Abstract: The primary cable of compressed conductor is properly a low tension primary cable with the particularity of having a same sectional area that permits to conduct, the same amount of electric current to any part of an automotive vehicle. However, its external diameter is much more smaller related to a same calibre of the same nature because of the compression that it suffers during the process of the compacted joining in a joining machine. The cable of compressed conductor has several advantages over other conventional primary cables, since a bigger standardization in the insulator thickness is found and in this way, a standardization on the results of the chemical-physical, and mechanical tests is accomplished. (These tests are compulsory because of its design).

Description: The present invention relates to compressed conductor low tension primary cables, particularly but not exclusively to compressed conductor low tension primary cables for use in automotive wiring harnesses. During recent decades, the automotive industry has undergone a technological transformation. This has in turn necessitated technological improvements in automotive equipment and accessories, the most important improvement being in the electronics area and relating particularly to the manufacture of automotive low tension primary cables. Advancements in this field have required a reduction in cable cross-sectional area whilst maintaining the ability to conduct the same electric current. Cable insulation techniques have also improved, resulting in reduced insulation wall thickness and allowing greater cable compression. The use of compacted or compressed primary cables allows the use of smaller automotive wiring harnesses, which is especially important in vehicles having modern aerodynamic designs in which space can be limited. This leads to an overall vehicle weight reduction and hence fuel saving. The use of compacted or compressed primary cables also allows a larger amount of electric circuitry to be stored in a given space. This is of increasing importance as the amount of electric circuitry required in vehicles is constantly increasing, such circuitry being provided inter alia for the following purposes and electrical devices: Security and Convenience such as weather control, crossing control, key entrance alarms, "lights on" reminders, cleaning sensors, door alarms and window control mechanisms; Powertrain such as machine dynamics, ignition timing, combustion liberators, spark distributors, turbo controls, emission monitors, voltage regulators, alternators; Entertainment Systems such as noise reduction systems, cellular radiotelephone systems, compact disc and audio tape systems, CB radios, audio digital tapes, etc; Driver Information Systems such as digital and analogue pressures indicators, machine diagnostics, service indicators, digital clocks, navigation computers, intelligent trajectory systems, collision avoidance systems, driver alerts, etc; Body Control Systems such as multiplex cables, internal module networks, dynamic ride control systems, active suspension systems, electronic steering systems, electronic sound suppression systems, etc. It will be appreciated that not only does the amount of electric circuitry present in an automotive vehicle influence the size and space available in the vehicle but also its weight and design. It is known from EP 0331182 A1 to provide a compact conductor cable for use in an automotive wiring harness. This conductor cable includes a central element wire surrounded by peripheral wires which are chosen to have a lower hardness than the central element wire. It is also known from US 5449861 to provide a compact conductor cable for use in an automotive wiring harness in which a central element wire is surrounded by peripheral wires, the cable being compressed by die drawing and being surrounded by insulating material. According to the present invention there is provided a compressed conductor low tension primary cable as for use in an automotive wiring harness comprising a conductor nucleus including a central wire and a single peripheral row of pre-drawn copper wires surrounding the central wire, and an external cover extruded from an insulating material surrounding the conductor nucleus and comprising polyvinylchloride characterised in that the external cover is located directly adjacent to the conductor nucleus, in that the cable is compacted by twisting the conductor nucleus until close to its limit of electrical resistance so that the nucleus is free from internal voids between the wires and external voids between the peripheral row and the external cover, and further characterised in that the cross-sectional area of the central and peripheral wires, and hence the electrical resistance of the cable, is unaffected by said compaction. Further preferred features of the invention are defined in the sub-claims. An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Fig. 1 is a cross-sectional view of a cable according to the invention, the cable including wires of cross-sectional area 0.35mm 2 ; Fig. 2 is a cross-sectional view of a cable according to the invention, the cable including wires of cross-sectional area 0.50mm 2 ; and Fig. 3 is a cross-sectional view of a cable according to the invention, the cable including wires of cross-sectional area 0.75mm 2 The fabrication- of the compressed conductor low tension primary cable 10 of the present invention requires accuracy during the extrusion of the insulating cover and a reduction in wire size. To achieve these objectives, it is necessary to respectively select a high performance insulating material and to employ equipment to reduce the cross-sectional area of the cable. The compressed conductor primary cable 10 is a low tension primary cable, the central wire 15 and peripheral wires 13 surrounding the central wire having the same cross-sectional area after compaction as before compaction. However, the outer diameter 12 of the cable 10 is smaller than the diameter of a cable having similar performance characteristics which has been compacted in a joining machine. The cable 10 is fabricated with red copper wires 13, drawn as a first stage by a one-row drawing machine. As a second stage, a joining machine with a pre-twister is used so that the joining and compaction operations can be carried out simultaneously. During the final stage, an external cover 14 is extruded from an insulating material to surround the central wire 15 and peripheral wires 13. The external cover 14 is formed from polyvinylchloride (PVC) rated for operation at a temperature in the order of 90°C. The external cover 14 has thin walls and a high abrasion resistance. The compressed conductor low tension primary cable 10 has several advantages in comparison to conventional primary cables, since an improved standardisation is found in the thickness of the external cover 14 which leads to a standardisation in terms of the results obtained from chemical, physical and mechanical tests which are compulsory because of cable design. The compressed conductor low tension primary cable 10 is designed for use in an automotive wiring harness which will be exposed to operating temperatures from -40°C to 105°C, the range of operating temperatures ultimately being dictated by the design of the electrical systems. In a preferred embodiment, the conductor nucleus includes a central wire 15 surrounded by at least one peripheral row of six wires 13, which are pre-drawn. The peripheral wires 13 have a calibre of 0.0325mm and a cross-sectional area of 0.35mm 2 , the walls of the external cover being 0.2mm thick. The cable 10 is compacted so that the maximum electric resistance is achieved since it is this parameter which will have a large influence on cable design. When fabricating the cable 10, the external insulating cover must be precisely extruded to achieve a reduction in the cross-sectional area of the cable. To achieve such precision, it is necessary to appropriately select the insulating material used to form the external cover and also the equipment used to extrude the cable 10. The principal advantages of the cable 10 are; A) Reduced weight compared to conventional compressed conductor primary cables. B) Thinner wiring harnesses may be used to accommodate the compressed conductor low tension primary cable. C) A larger amount of electric circuitry can be accommodated in wiring harnesses. D) Improved terminal application, by allowing displacement of the external cover. E) Improved productivity in the extrusion process, thus reducing equipment downtime caused by thread (loose wires). F) The achievement of required performance standards in abrasion, oil, heat, tension, extension and low temperature tests. The composition of a preferred compressed conductor low tension primary cable 10 is shown in the following table. PARAMETER SPECIFIED VALUE Diameter 7.620 to 8.38 mm 8.00 mm + -0.38m Extension 30% minimum Twist resistance 50° minimum Conductivity 101.00% IACS minimum Resistance 0.15176 Ω g/m 2 maximum Oval 0.50 mm maximum

Claims: A compressed conductor low tension primary cable for use in an automotive wiring harness comprising a conductor nucleus including a central wire and a single peripheral row of pre-drawn copper wires surrounding the central wire, and an external cover extruded from an insulating material surrounding the conductor nucleus and comprising polyvinylchloride characterised in that the external cover is located directly adjacent to the conductor nucleus, in that the cable is compacted by twisting the conductor nucleus until close to its limit of electrical resistance so that the nucleus is free from internal voids between the wires and external voids between the peripheral row and the external cover, and further characterised in that the cross-sectional area of the central and peripheral wires, and hence the electrical resistance of the cable, is unaffected by said compaction. A cable according to Claim, 1, wherein the polyvinylchloride (PVC) is rated for operation at temperatures in the order of 90°C. A cable according to Claim 1 or Claim 2, wherein the cable is adapted for exposure to operating temperatures from -40°C to 105°C.

Inventors: CORONA ARTEMIO MARTINEZ, GUTIERREZ CARLOS TENORIO, CORONA, ARTEMIO MARTINEZ, GUTIERREZ, CARLOS TENORIO
Applicants: SERVICIOS CONDUMEX SA, SERVICIOS CONDUMEX S.A. DE C.V.
Application year: 1998
Main classification: H01B7
IPC codes: H01B7