WO2011064212A1

WO2011064212A1 - Cable

Info

Publication number: WO2011064212A1
Application number: PCT/EP2010/068039
Authority: WO
Inventors: Gregor Karrasch; Andreas Sattler
Original assignee: Tyco Electronics Amp Gmbh
Priority date: 2009-11-27
Filing date: 2010-11-23
Publication date: 2011-06-03
Also published as: DE102009047223B3

Abstract

The present invention relates to a cable, comprising at least one wire (110) and a contact arrangement (120), wherein the contact arrangement (120) comprises a contact element (125, 126) connected to the wire (110). The cable also comprises an electrical conductor (150, 151, 152) which in the region of a cable section adjoining the contact arrangement (120) is spirally wound around the at least one wire (110). The invention also relates to a method for producing a cable having a contact arrangement (120).

Description

CABLE

The present invention relates to a cable, comprising at least one wire and a contact arrangement, wherein the contact arrangement comprises a contact element connected to the wire. The invention also relates to a method for producing a cable having a contact arrangement.

Cables are used to transmit power for an electricity or power supply and/or to transmit items of information. Conventional cables comprise one or more wire(s) which are sheathed, for example in a circular manner, by an insulator, what is referred to as the sheath. The wires are also called insulated conductors. In the case of a multi-wire cable the individual wires are, moreover, surrounded by a separate insulator, the wire insulation, while the cable sheath sheaths all wires. A shielding, which is conventionally in the form of a wire mesh, may also be provided between the cable sheath and the wires.

Known cables also have contact arrangements at their ends, by which the cables can be connected to other devices (or cables). The contact arrangements comprise contact elements which are connected to the wires of the relevant cables. A contact arrangement is

conventionally in the form of what is known as a plug-in connector which can be plugged together with a complementary plug-in connector counterpart. Possible embodiments of plug- in connectors are plugs and sleeves or couplings.

To provide a (multi-wire) cable having a contact arrangement, firstly part of the cable sheath and the shielding is removed in the region of a cable end, then the contact arrangement or its contact elements are connected to the cable wires and the cable end is provided with an appropriate casing. In a known embodiment a metallic crimp is also arranged in the region of the cable section, in which the shielding is removed, before the casing is attached, and surrounds the wires of the cable. The crimp, which is also called an 'impedance crimp', is intended to compensate for the absence of the shielding, so the cable in this region also has an optimally homogeneous impedance characteristic, based on the extent of the cable. Despite this solution the problem can exist where the impedance behaviour of a cable may be only insufficiently homogenised. The shielding sheaths the wires of the cable relatively closely and at a uniform distance, whereas an impedance crimp does not allow such properties to be formed in relation to the wires, or only allows them to form with great difficulty.

Consequently there can be a relatively large change in impedance in the region of the impedance crimp. This drawback occurs in particular if the wires in the shielded cable section are arranged relatively close to each other and have a greater distance from each other in the region of the contact elements, so the distance between the wires changes in the region located therebetween in which the impedance crimp is also arranged.

Embodiments of cables are also known in which the cable has a bend of, for example, 90° upstream of the relevant contact arrangement. In such a case an impedance crimp can only partially surround the wires, whereas the wires in a cable section adjoining the contact arrangement are not surrounded by the impedance crimp. This also leads to a relatively large change in impedance.

An inhomogeneous impedance characteristic along the electrical path or signal path can lead to disruptive reflections during operation of the relevant cable. This is a problem in particular for high-speed applications, such as HSD (high speed data), in which the cables are used to transmit signals with relatively high frequencies.

A further drawback is that different cables or different bends in cables require the use of separate impedance crimps and this is associated with relatively high expenditure. The use of rigid impedance crimps can, moreover, lead to wire insulation being squashed during assembly and possibly being damaged. Such consequences can also occur later during the operation time of the cable, for example owing to mechanical stresses or vibrations and temperature-induced expansions.

The object of the invention consists in providing an improved cable which is characterised in particular by more homogeneous impedance behaviour. This object is achieved by a cable according to claim 1 and by a method according to claim 10. Further advantageous embodiments of the invention are specified in the dependent claims.

According to the invention a cable is proposed which comprises at least one wire and a contact arrangement. The contact arrangement comprises a contact element connected to the wire. The cable also comprises an electrical conductor which, in the region of a cable section adjoining the contact arrangement, is spirally wound around the at least one wire.

In contrast to a rigid impedance crimp, a wound electrical conductor can be provided with a flexible shape which can be adapted to the respective spatial conditions. In particular the electrical conductor can be wound in such a way that the electrical conductor sheaths (at least one) wire at a uniform distance or surrounds it as closely and proximately as possible. The impedance behaviour of the cable can consequently have relatively high homogeneity or linearity which results in improved reflection behaviour and therefore improved signal transmission behaviour. Due to the flexible shape the electrical conductor may also be used for a large number of different cables. Damage to the (at least one) wire may also be avoided during assembly. As the shape of the electrical conductor, fixed during assembly, can itself still change later impairments during operation of the cable as a result of, for example, mechanical stresses and temperature-induced expansions, may also be avoided.

In a preferred embodiment the cable comprises a shielding section in which the at least one wire is surrounded by a shielding. The shielding section adjoins the cable section with the electrical conductor. Like the shielding, the electrical conductor can surround the (at least one) wire as homogeneously and closely as possible, so the impedance of the cable in the region of the electrical conductor is adjusted to the impedance present in the region of the shielding section. This makes a homogeneous impedance characteristic possible at the transition region between the shielding section and the contact arrangement.

Various preferred embodiments may be considered in relation to the electrical conductor. The electrical conductor can, by way of example, be a strand. In this case the strand can be a bare wire, making possible an electrical connection between the windings of the wound electrical conductor.

In a further preferred embodiment the electrical conductor is a flattened wire. This results in the possibility of winding the conductor in such a way that adjacent windings completely overlap at the sides. As a result the (at least one) wire of the cable can be comprehensively surrounded by the electrical conductor in the region of the cable section adjoining the contact arrangement.

In a further preferred embodiment the electrical conductor is a flex which comprises a plurality of strands. Optimally complete sheathing of the (at least one) wire may be achieved as a result of this as well.

In a further preferred embodiment the cable comprises a bend in the region of the cable section with the electrical conductor. The bend, which, for example, can enclose an angle of substantially 90°, makes it easier to connect the cable with the contact arrangement to a complementary contact arrangement. The flexible shape of the wound electrical conductor proves to be advantageous in particular with a bent design of the cable. In the region of the bend, the electrical conductor can be arranged completely and directly around the (at least one) conductor, whereby the cable has optimally uniform impedance over its length. In contrast to a rigid impedance crimp, a wound electrical conductor can also be used for a large number of different bends or bending angles.

In a further preferred embodiment the cable comprises a plurality of wires. The contact arrangement comprises a plurality of contact elements which are each connected to a wire. Here the electrical conductor is spirally wound around the plurality of wires in the region of the cable section adjoining the contact arrangement.

In a further preferred embodiment the wires have a greater distance from each other in the region of the contact arrangement than in a cable section spaced apart from the contact arrangement. The flexible shape of the wound electrical conductor offers the possibility, even with such a change in distance of the wires, of surrounding the wires at a uniform distance or as proximately as possible, and this promotes homogeneous cable impedance behaviour.

According to the invention a method for producing a cable having a contact arrangement is also proposed, wherein the cable comprises at least one wire and the contact arrangement comprises a contact element. In the method the contact element is connected to the wire. It is also provided that an electrical conductor is spirally wound around the at least one wire in the region of a cable section adjoining the contact arrangement. The cable produced in this way exhibits more homogeneous impedance behaviour. The method may also be used for a large number of different cables. Problems, such as damage to the (at least one) wire, may also be avoided.

The invention will be described in more detail hereinafter with reference to the figures, in which:

Figs. 1 to 6 show production of a cable having a contact arrangement in different schematic views, an electrical conductor being used for homogenisation of the impedance,

Figs. 7 and 8 show impedance characteristics which were measured for impedance homogenisation on a conventional cable and on a cable with an electrical conductor,

Figs. 9 and 10 show reflection characteristics which were measured for impedance homogenisation on a conventional cable and on a cable with an electrical conductor, and

Figs. 11 and 12 show further cables, each in a schematic view.

The following figures show embodiments of cables in which an electrical conductor is spirally wound around wires of the cable in a region of a cable section adjoining a contact arrangement in order to achieve homogeneous impedance behaviour of the respective cable. The cables are therefore particularly suitable for high-speed applications, such as HSD (high speed data), as the signal transmission prevents impairing reflections, or these may be largely suppressed. An arrangement of this kind may be provided at both ends of a cable, which optionally have complementary contact arrangements or plug-in connectors.

Figures 1 to 6 show production of a cable 100 having a contact arrangement 120 in the form of a sleeve plug-in connector, it being possible to also use an electrical conductor 150 for impedance homogenisation. The exact construction of the cable 100 can be seen with the aid of the method. The cable 100 is, for example, a four- wire HSD cable in which a contact arrangement 120 in the form of a socket connector is provided at the end of the cable shown in the figures.

Fig. 1 shows a schematic view of the cable 100 on which first method steps have already been carried out. Figures 2 and 3 show, furthermore, schematic sectional views which are based on the cutting lines A-A and B-B shown in Fig. 1. The cable 100 comprises four wires 110. Each of the wires 110 comprises an (electrically conductive) insulated conductor 111 which is sheathed by conductor insulation 112 (cf. Figs. 2 and 3). During operation of the cable 100 two wires 110 respectively, for example, arranged diagonally to each other, can be used as a signal line pair.

With the method firstly the cable 100 is provided, which over its entire length has a construction matching that in Fig. 2. The wires 110 are arranged in a close distance grid in which the wires 110 directly adjoin each other. The wires 110 are also surrounded by a shielding 131 and the shielding 131 is surrounded by an insulating cable sheath 132. The shielding 131 is constructed, for example, in the form of a wire mesh or netting and is used to ensure the electromagnetic compatibility (EMC) of the cable 100. The shielding 131 should ensure that electromagnetic fields acting on the cable 100 from the outside on the one hand, and electromagnetic fields emanating from the cable 100 on the other hand, are shielded in order to avoid interference associated herewith.

As shown in Fig. 1, firstly part of the cable sheath 132 and part of the shielding 131 are removed from the provided cable 100, whereby the wires 110 are exposed and separated. The cable sheath 132 is removed more than the shielding 131. The shielding 131 therefore has a free section which, as indicated in Fig. 1, can protrude from the wires 110 or be bent away from them. After exposing the wires 110, the individual wires 110 or their insulated conductors 111 are each connected to a contact element in the form of a contact sleeve 125. For this purpose a crimping method (crimping), for example, may be carried out, it being possible for part of the conductor insulation 112 surrounding the insulated conductors 111 to be removed in advance. It is also possible to carry out a soldering process.

The contact sleeves 125 connected to the wires 110 are, as also shown in Fig. 1, arranged or secured in associated recesses of an insulating holding element 121, whereby the contact arrangement 120 is substantially finished. The contact sleeves 125 are arranged in a predefined distance grid in the holding element 121, which in the present case is also called a "socket body". This also applies to the wires 110 in a region upstream of the contact arrangement 120, as can be seen with the aid of Fig. 3. At this point the wires 110 have a greater distance from each other than in the shielding section shown in Fig. 2 in which the wires 110 are arranged so as to adjoin each other and are directly surrounded by the shielding 131. In the "shielding-free" region between the shielding section and the contact arrangement 120 the distance between the wires 110 therefore changes, as shown in Fig. 1.

As shown in Fig. 4, an electrical conductor 150 is then spirally wound around the wires 110 in a section of the cable 100 between the shielding section and the contact arrangement 120 or from the point of separation of the wires 110 to the contact arrangement 120. Such a winding step can be easily and quickly carried out. The electrical conductor 150 can, by way of example, be a bare strand 150 which is formed from an electrically conductive or metallic material (for example copper) and has, for example, a round or circular cross-section.

Contrary to the diagram in Fig. 4 (and in figures 5 and 6), the windings of the wire 150 can be wound relatively close to each other to ensure that adjacent windings at least partially touch or even overlap, and the wires 110 are therefore substantially completely surrounded by the wire 150. As indicated in figures 4 to 6, the wire 150 may also, be wound around the wires 110 in either a single layer or alternatively in a plurality of layers (not shown).

Winding means the strand 150 can be arranged around the wires 110 uniformly, or as closely and directly as possible. In contrast to a conventional impedance crimp this is even possible if, as in the present case, the distances of the wires 110 from each other change in the region of the shielding-free cable section. Owing to this property the strand 150 is better suited than an impedance crimp to imparting optimally homogeneous or linear impedance behaviour to the cable 100, based on the cable length. This will be discussed in more detail below.

After attaching the strand 150 the cable 100 is bent, as shown in Fig. 5, so there is a bend 105 in the region of the strand 150. The bend 105, which, for example, allows easier connection of the produced cable 100 with the contact arrangement 120 to a complementary contact arrangement, can enclose an angle of, for example, substantially 90°. The wound strand 150 proves to be advantageous in this connection as well, as with its flexible shape the strand 150 can adjust to the bend 105 in the cable 100, so, even after bending, the wires 110 may be sheathed substantially completely and directly by the wire 150.

Instead of winding the strand 150 around the wires 110 of the cable 100 before producing the bend 105, such a step may alternatively be carried out only after the bend 105 has been produced. Even with this kind of procedure the strand 150 can be arranged around the wires 110 as directly and completely as possible owing to winding.

Further method steps are subsequently carried out in order to complete the cable with the construction shown in Fig. 6. A casing 141 is arranged on the cable end and this encloses the contact arrangement 120 and has a bent shape adapted to the bend 105. Two casing halves, by way of example, may be joined to provide the casing 141. The casing 141, which comprises an electrically conductive or metallic material, extends in this case substantially up to the shielding section of the cable 100 (in which the wires 110 are proximately sheathed by the shielding 131).

The casing 141 is used to allow shielding of the cable 100 in the region of the cable end or the contact arrangement 120. The previously protruding section of the shielding 131 is arranged on the casing 141 for this purpose, as shown in Fig. 6. A fixing sleeve 142 is also provided in this region which presses the shielding 131 onto the casing 141, so the casing 141 is electrically connected to the shielding 131. The fixing sleeve 142 can comprise an electrically conductive or metallic material.

In contrast to a rigid impedance crimp, the shape of the wire 150 may be flexibly determined by winding. The wire 150 can therefore be formed around the wires 110 with an optimally uniform or proximate distance in relation to the wires 110, so the cable 100 has relatively homogeneous impedance behaviour or a relatively homogeneous impedance characteristic, based on its longitudinal extension. Improved reflection behaviour and therefore signal transmission behaviour is associated herewith. The advantage of the flexible shape with respect to an impedance crimp occurs in particular if, as in the present case, the distance of the wires 110 from each other changes (transition from a narrow to a widened distance grid) and the cable 100 has a bend 105. Even with the existence of a bend 105 the wire 150, like the shielding 131, can surround the wires 110 as closely and symmetrically as possible, and this is possible in particular in a region directly up to the contact arrangement 120. The impedance of the cable 100 in the shielding-free section, in which the shielding 131 is removed, is therefore adapted to the impedance that exists in the region of the shielding section due to use of the conductor 150.

A further advantage of the flexible shape of the wound wires 150 is that damage to the wires 110 or their insulation 112 can be avoided during assembly. The shape of the wire wrap can also still change after production, so impairments during operation of the cable 100 owing to, for example, mechanical stresses and temperature-induced expansions may be avoided. Furthermore, a conductor or wire 150 of this kind can be provided for impedance

homogenisation in the case of a large number of different cables, which cables may differ for example due to different bends, number of wires, diameters, etc.

In addition to impedance homogenisation the wound wire 150 can optionally also make it possible to shield the wires 110. Shielding of the wires 110 in this region is already brought about by the casing 141, however, and is therefore of secondary importance for the wire wrap. The advantageous use of an electrical conductor spirally wound around wires of a cable, which makes improved signal transmission possible, will be clarified with reference to figures 7 to 10 below. Figures 7 and 8 show characteristics 160, 161 of the impedance Z as a function of time t which were measured on a conventional cable (impedance characteristic 160 in Fig. 7) and on a cable with an electrical conductor or wire wrap (impedance characteristic 161 in Fig. 8). A time-domain reflectometer was used for measuring which reproduces the impedance characteristic based on the cable length in a time-resolved manner. The measured cables had a construction comparable to cable 100 in Fig. 6, wherein, instead of an electrical conductor, the conventional cable had an impedance crimp in the region of the shielding- free section which, owing to a cable bend of 90°, did not extend directly up to the relevant contact arrangement.

In the two figures 7, 8 the start of the respective cable is shown by a broken line 163. The sections of the impedance characteristics 160, 161 upstream of or to the left of this line 163 reproduce characteristics of the measuring construction or instrument used. A lower limit value 165 and an upper limit value 166 are also shown for the impedance Z.

In the case of the impedance characteristic 160 of the conventional cable in Fig. 7, there is a superelevation in the region of an instant identified by a further broken line 164 and this emanates from a transition between contact elements or contact sleeves and the wires of the cable. Regions 167, 168 are also shown. In this case the region 167 relates to a cable section in which the wires are not surrounded by the impedance crimp (owing to the cable bend). The region 168 relates to a cable section in which, by contrast, the wires are surrounded by the impedance crimp. Owing to the cable section without impedance crimp (region 167) the upper limit value 166 in the case of impedance characteristic 160 is significantly exceeded over a relatively large time segment.

In the case of the impedance characteristic 161 shown in Fig. 8, a region 169 is illustrated in which an electrical conductor in the form of a strand is wound around the wires of the cable. In contrast to the impedance characteristic 160 in Fig. 7, impedance characteristic 161 is more uniform and has greater homogeneity or linearity. The upper limit value 166 is also exceeded in the case of impedance characteristic 161 in the region of instant 164 (by a smaller amount, i.e. with a smaller height and width, in contrast to impedance characteristic 160), but this can be attributed to the fact that the measurement was carried out with a relatively high measuring resolution.

The advantageous use of the electrical conductor also becomes clear with the aid of the reflection characteristics 170, 171 shown in figures 9 and 10 and recorded using an additional measuring instrument. These show a reflection coefficient Ar as a function of the frequency f and again refer to the conventional cable (characteristic 170 in Fig. 9) and to the cable with the wound electrical conductor (impedance characteristic 171 in Fig. 10). The characteristic of an upper limit value 175 is also shown in the two figures 9 and 10. The reflection characteristic 170 obtained on the conventional cable exceeds limit value 175 at relatively high frequencies. In contrast, the limit value 175 is not exceeded in the case of reflection characteristic 171 owing to the use of the wire wrap.

Alternative embodiments are conceivable instead of using a strand 150 with a round or circular cross-section as the electrical conductor. By way of exemplary illustration the following figures 11 and 12 show further cables 101, 102 with an electrical conductor 151, 152 which, apart from the conductors 151, 152, may have a comparable construction, with corresponding or similar components, to the cable 100 described in figures 1 to 6. In this case the illustration of a shielding, a cable sheath, a fixing sleeve and a casing that may be provided in these cables 101, 102 as well is omitted. The illustration of a (optional) cable bend is also omitted. Reference is made to the above statements with regard to the details, which refer to identical or corresponding components, method steps that can be used for production and advantages already described.

Fig. 11 shows a further embodiment of a cable 101. In contrast to the cable 100 in Fig. 6, a contact arrangement 120 is provided which comprises contact pins 126 instead of contact sleeves 125. These are arranged inside an insulating holding element 122 and are connected to wires 110 of the cable 101.

In the case of cable 101 a flattened wire 151 is used in the region of a cable section adjoining the contact arrangement 120 (and adjoining a shielding section, not shown) for impedence homogenisation and this is spirally wound around the wires 110. The flattened wire 151 may also be wound around the wires 110 with a shape flexibly adapted to the respective spatial conditions. The flattened wire 151 may also be wound in such a way (in one layer) that all adjacent windings overlap at the sides, so the wires 110 in the shielding-free cable section are completely sheathed by the flattened wire 151. A multi- layer arrangement is also possible.

Instead of the contact arrangement 120 with the contact pins 126, a contact arrangement 120 with contact sleeves 125 may also be provided in cable 101 in Fig. 11.

Equally, a contact arrangement 120 with contact pins 126 may be provided instead of the contact arrangement 120 with the contact sleeves 125 in the case of cable 100 in figures 1 to 6. This also applies to cable 102 described below.

Fig. 12 shows a further embodiment of a cable 102. Like cable 100, cable 102 has a contact arrangement 120 with contact sleeves 125 which are arranged in an insulating holding element 121 and are connected to wires 110.

A flex 152 spirally wound around the wires 110 is provided in the region of a cable section adjoining the contact arrangement 120 (and adjoining a shielding section, not shown), and, as Fig. 12 indicates, this flex incorporates a plurality of strands. The flex 152 can likewise be wound here in such a way (single layer or multi-layer) that optimally complete sheathing of the wires 110 is achieved.

The embodiments of cables described with the aid of figures and methods for their production constitute preferred or exemplary embodiments of the invention. In addition to the described and depicted embodiments, further embodiments are conceivable which can comprise further modifications or combinations of features. By way of example, wound wires may be used which have a different profile or a different cross-section to a round cross-section or a flat profile. Wires may optionally also be used which have separate external insulation, for example in the form of a paint. Apart from the described 90° bend, cables may also comprise other bends which can cover an angle in a range between 0° and 360°. The described methods for impedance homogenisation are also not restricted to multi- wire cables but may also be used in cables which have only one wire or one internal conductor. It is possible, moreover, for electrical conductors or wire wraps to not just be constructed around wires of a cable so as to adjoin a contact arrangement; the conductors may also be wound in such a way that, additionally, (at least) part of a contact arrangement or an insulating holding element is also would around, for example to achieve improved fixing of the electrical conductor. This applies equally to a section of a cable in which there is a shielding. The shielding and an electrical conductor arranged wires can also abut and to an extent overlap.

With regard to the method described with reference to figures 1 to 6, reference is also made to the fact that this method is only one possible method for producing a cable with a contact arrangement and a conductor for impedance linearization and, as a result, should only be regarded as an example. Further embodiments of methods are also conceivable in which optionally other or further method steps are carried out and optionally other or additional components are used.

Claims

1. Cable, comprising: at least one wire (110), and a contact arrangement (120) which comprises a contact element (125, 126) connected to the wire (110), characterised by an electrical conductor (150, 151, 152) which in the region of a cable section adjoining the contact arrangement (120) is spirally wound around the at least one wire (110).

2. Cable according to claim 1, comprising a shielding section in which the at least one wire (110) is surrounded by a shielding (131), wherein the shielding section adjoins the cable section with the electrical conductor (150, 151, 152).

3. Cable according to either of the preceding claims, wherein the electrical conductor is a strand (150, 151).

4. Cable according to any one of the preceding claims, wherein the electrical conductor is a flattened wire (151).

5. Cable according to either of claims 1 or 2, wherein the electrical conductor is a flex (152) which comprises a plurality of strands.

6. Cable according to any one of the preceding claims, wherein the cable has a bend (105) in the region of the cable section with the electrical conductor.

7. Cable according to any one of the preceding claims, wherein the cable comprises a plurality of wires (110), wherein the contact arrangement (120) comprises a plurality of contact elements (125, 126) which are each connected to a wire (110), and wherein the electrical conductor (150, 151, 152) is spirally wound around the plurality of wires (110) in the region of the cable section adjoining the contact arrangement (120).

8. Cable according to claim 7, wherein the wires (110) have a greater distance from each other in the region of the contact arrangement (120) than in a cable section spaced apart from the contact arrangement.

9. Cable according to any one of the preceding claims, wherein a contact element is a contact sleeve (125) or a contact pin (126).

10. Method for producing a cable comprising a contact arrangement (120), wherein the cable comprises at least one wire (110), wherein the contact arrangement (120) comprises a contact element (125, 126) which is connected to the wire (110), characterised in that an electrical conductor (150, 151, 152) is spirally wound around the at least one wire (110) in the region of a cable section adjoining the contact arrangement (120).