EP2697804B1 - Star-quad cable with shield - Google Patents

Description

The present invention relates to a star quad cable for transmitting electrical signals with at least two pairs of electrical conductors, wherein each conductor comprises a core of an electrically conductive material and a conductor surrounding the wire conductor shell of an electrically insulating material, wherein the conductors in a Cross section of the star quad cable are arranged at the corners of a square, wherein the conductors of a pair are arranged at diagonally opposite corners of the square, wherein four conductors are twisted together according to a star quad array with a predetermined stranding factor, wherein one of the two pairs of Conductors radially outwardly surrounding screen is disposed of an electrically conductive material, wherein between the conductors and the screen, an additional insulator shell of an electrically insulating material is arranged, wherein the screen is constructed of a mesh of individual shield wires, gem according to the preamble of claim 1.

A so-called "star quad" is a stranding element for conductors with, for example, copper wires. Four conductors of pairs of conductors are twisted together to form two cross-shaped stranded double conductors. Two opposing conductors form a pair, each transmitting an electrical signal on a pair. In other words, the four conductors in the cross section of the star quad are arranged at the corners of a square, wherein the conductors of a pair are arranged at diagonally opposite corners. By doing this vertically mutually standing conductor pairs results in a desired high crosstalk attenuation from one pair to the other pair.

The quad-core cable is one of the balanced cables. In this cable four conductors are stranded with each other in a cross shape. This means that the opposite conductors each form a conductor pair. Due to the mutually perpendicular conductor pairs only very low crosstalk occurs. Another advantage of the star quad stranding is, in addition to the mechanical stabilization of the arrangement of the conductors relative to one another, the higher packing density than in a pair stranding.

Due to the stranding, the conductors or individual cores become longer than the cable itself. Stranding factor specifies the ratio of single-conductor length to cable length. For example, the stranding factor for telecommunication cables is about 1.02 to 1.04. The stranding factor correlates with a pitch resulting from the helical arrangement of the stranded conductors. The pitch or slope or pitch indicates a thread at an axial distance of two thread notches.

From the generic document DE 14 90 692 A1 is a carrier frequency cable with a central stranding element in the form of a star quad known. Four polythene insulated strands are stranded with a lay length and surrounded by a polyethylene insulation. The polyethylene insulation is covered by a shielding braid made of copper wires. On the shield braid a PVC jacket is applied.

The invention has for its object to improve a star quad cable of the type above in such a way that the electrical properties of the cable are not significantly affected by aging, nor by the load with bending and torsional stresses in a transfer of the four-wire cable.

This object is achieved by a star quad cable og. Art solved with the features characterized in claim 1. Advantageous embodiments of the invention are described in the further claims.

For a four-wire cable, the o.g. It is inventively provided that at least one, in particular four shielding wires or at least one, in particular four Schirmaderbündel are stranded radially surrounding the conductors, that in each case at least one of the stranded stranded conductors or one of the Schirmaderbündel in the axial direction in each case substantially parallel to a vein a conductor runs, in each case a Schirmader or a Schirmaderbündel on the one hand and a wire on the other hand in the axial direction parallel to each other, that the Schirmader or the Schirmaderbündel and the wire lie at any point in the cross section of the four-star cable on the same diagonal of the square and the shield wire or the shield wire bundle is arranged on a side of the wire facing away from the square.

This has the advantage that shield currents are reduced, thereby preserving the transfer characteristics of the quad-core cable, even under bending and torsion loads that mechanically influence the shield. Settling phenomena in the quad-core cable are avoided and stripping of the quad-core cable is simplified since there is a reduced risk of damaging the wires when cutting an outer insulation jacket. In addition, the additional insulator jacket generates a radial bias on the conductor sheaths of the cores, whereby a mechanical stability of the star quad assembly is increased in bending and torsional loads. It is further achieved an improvement in the management of electrical shielding currents with corresponding improvement in the electrical properties of the star quad cable, at the same time a particularly good line is achieved by each one core associated shielding currents. A high mechanical flexibility of the star quad cable with substantially unchanged arrangement of the conductors relative to each other even with bending and torsional stresses on the four-wire cable is achieved by the fact that the screen is constructed of a network of individual shield wires.

A particularly secure guidance of the shield wires or shielding wire bundles in parallel along a respective wire of a conductor even with bending and torsional loads of the four-wire cable is achieved in that the shield wires or Schirmaderbündel are stranded with a stranding factor, which corresponds to a stranding factor of the ladder.

Good electrical conductivity coupled with low manufacturing costs is achieved by making the wires from copper.

A further improvement of the transmission characteristic of the star quad cable by enabling additional electrical compensation currents on the screen is achieved by the fact that radially outward on the screen, a second screen is arranged, which is electrically conductively connected to the screen. These equalizing currents made it possible to compensate for manufacturing tolerances which possibly lead to shielding wires and associated line not being exactly parallel to one another.

A particularly large-scale conduction of equalizing currents across the second screen is achieved in that the second screen is formed as a sheath or foil of an electrically conductive material.

A particularly good preservation of the flexibility of the star quad cable despite the second screen is achieved by the fact that the second screen is constructed from a network of individual second shield wires.

A high number of electrical contact points between the second screen cores of the second screen and the screen cores of the radially inner screen are achieved by the second screen cores opposite to the screen cores of the screen, in particular with a stranding factor which corresponds to the stranding factor of the screen cores of the screen. are stranded.

Fig. 1

eine bespielhafte Ausführungsform eines erfindungsgemäßen Sternvierer-Kabels perspektivischer Ansicht,

Fig. 2

das Sternvierer-Kabel gemäß Fig. 1 in schematischer Schnittansicht,

Fig. 3

eine schematische Schnittansicht eines herkömmlichen Sternvierer-Kabels mit einer graphischen Darstellung der Verteilung eines elektrischen Feldes,

Fig. 4

eine schematische Schnittansicht eines erfindungsgemäßen Sternvierer-Kabels mit einer graphischen Darstellung der Verteilung eines elektrischen Feldes,

Fig. 5

eine graphische Darstellung einer Transmission eines elektrischen Signals in Abhängigkeit von einer Frequenz für das herkömmliche Sternvierer-Kabel gemäß Fig. 3,

Fig. 6

eine graphische Darstellung einer Transmission eines elektrischen Signals in Abhängigkeit von einer Frequenz für das erfindungsgemäße Sternvierer-Kabel gemäß Fig. 4 und

Fig. 7

eine vereinfachte schematische Darstellung von miteinander verseilten Leitern und einer Schirmader der beispielhaften Ausführungsform des Sternvierer-Kabels gemäß Fig. 1 und 2.

The invention will be explained in more detail below with reference to the drawing. This shows in:

Fig. 1

an exemplary embodiment of a star quad cable according to the invention perspective view,

Fig. 2

the star quad cable according to Fig. 1 in a schematic sectional view,

Fig. 3

a schematic sectional view of a conventional star quad cable with a graphical representation of the distribution of an electric field,

Fig. 4

a schematic sectional view of a star quad cable according to the invention with a graphical representation of the distribution of an electric field,

Fig. 5

a graphical representation of a transmission of an electrical signal in response to a frequency for the conventional star quad cable according to Fig. 3 .

Fig. 6

a graphical representation of a transmission of an electrical signal as a function of a frequency for the star quad cable according to the invention according to Fig. 4 and

Fig. 7

a simplified schematic representation of stranded conductors and a shield wire of the exemplary embodiment of the star quad cable according to Fig. 1 and 2 ,

The in the Fig. 1 and 2 illustrated, preferred embodiment of a star quad cable according to the invention comprises four conductors 10, 12, 14, 16, each having a core 18 made of an electrically conductive material and a conductor shell 20 made of an electrically insulating material. The conductors 10, 12, 14, 16 are twisted together to form a star quad array, ie at each point in the cross section of the four-wire cable are the conductors 10, 12, 14, 16 at a corner of a square 17. Each on a diagonal 19 of the square 17 opposite conductors 10, 12 and 14, 16 form a pair, ie the conductors 10, 12 form a first pair of conductors or a first conductor pair 12, 14 and the conductors 14, 16 form a second pair of conductors or a second pair of conductors 14, 16. The twist of the conductors 10, 12, 14, 16 is carried out with a predetermined stranding factor, which requires a corresponding pitch or pitch s. The lay length s is in this case the axial distance at which a conductor 10, 12, 14, 16 once helically winds completely around a longitudinal axis of the four-star cable. In Fig. 2 a coordinate system with an x-axis 40 and a y-axis 42 is shown. The coordinate system 40, 42 is arranged such that the origin 44 of the coordinate system 40, 42 lies exactly on the longitudinal axis of the star quad cable, so that this longitudinal axis forms a z-direction in space for the coordinate system 40, 42.

In the signal transmission, a first signal is transmitted to the first pair of conductors 10, 12, and a second signal is transmitted to the second pair of conductors 14, 16. By a corresponding phase shift between the first and second signal and the previously described spatial arrangement of the conductors 10, 12, 14, 16 relative to each other in a star quad array is in a known manner, a high crosstalk attenuation between the two conductor pairs 10, 12 and 14, 16 achieved. In a so-called differential mode, the signals on the conductor pairs 10, 12 and 14, 16 have a phase shift of 180 °.

The stranded conductor 10, 12,14, 16 radially surrounding the outside of a screen 22 is arranged, which is constructed of discrete or individual shield wires 23. A jacket 25 made of an electrically insulating material surrounds radially outside the entire structure of conductors 10, 12, 14, 16 and screen 22. Between the stranded conductor pairs 10, 12 and 14, 16 on the one hand and the screen 22 on the other hand, an additional insulating jacket 24 is made arranged an electrically insulating material. This creates an additional spatial distance in the radial direction between the wires 18 of the conductors 10, 12, 14, 16 on the one hand and the screen 22 on the other. The resulting effect will be described below with reference to FIGS Fig. 3 and 4 explained.

In Fig. 3 a schematic sectional view of a conventional star quad cable with conductors 10, 12, 14, 16 with respective wires 18 and conductor shrouds 20 and a screen 22 is shown. The screen 22 is radially outward directly on the conductor shrouds 20 of the conductors 10, 12, 14, 16, so that there is a minimum radial distance between the wires 18 and the screen 22. Arrows show the distribution of an electric field when transmitting corresponding electrical signals via the conductors 10, 12, 14, 16, the greater the electric field, the larger the respective arrow is shown. It is off Fig. 3 to recognize that a strong electric field between the wires 18 of the second pair of conductors 14, 16 and the screen 22 is formed. This indicates correspondingly high electrical currents along the screen 22, which are referred to below as "screen currents". High shield currents lead to all the effects that affect the screen 22, a high influence on the electrical properties or the transmission characteristics of the quad-core cable result. For example, bending and torsional stresses of the star quad cable, which result in mechanical deformation or even damage to the screen 22, lead to a severe deterioration in the electrical characteristics of the four-wire cable, although the cores of the star quad Cable may not be affected by mechanical changes or damage. Furthermore, the screen 22 is usually formed as a mesh of individual shield wires 23 and shield currents must, for example, to follow a wire 18 at contact points of shield wires 23 from a shield wire 23 to another switch. If, over time, these contact points age, there is a meaningful impediment to the current flow of the shield currents and thereby a concomitant deterioration in the transmission of electrical signals throughout the entire quad-core cable, although no age-related mechanical degradation has occurred in the conductors 18 themselves ,

Fig. 4 shows in an analog view like Fig. 3 the distribution of the electric field for a star quad cable formed with the additional insulator jacket 24. Here, the screen 22 by the between the conductors 10, 12, 14, 16 on the one hand and the screen 22 on the other hand arranged additional Insulating jacket 24 a greater radial distance from the wires 18, as in the conventional embodiment of a star quad cable according to Fig. 3 , It turns out Fig. 4 in that the electric field is now concentrated between the conductors 10, 12, 14, 16. This means that with a star quad cable according to the invention significantly less screen currents result in the signal transmission. As a result, the previously with respect to Fig. 3 Accordingly, the effects described by a deterioration of the screen 22 in the star quad cable designed according to the invention accordingly have less of an influence on the electrical properties of the star quad cable in terms of signal transmission. For example, degradation is an increase in attenuation for a useful signal in the quad-core cable. Even if the screen 22 is damaged or aged, the transmission characteristics of the star quad cable are significantly less adversely affected. In other words, the star quad cable designed according to the invention is considerably more resistant to damage or aging of the screen 22 in terms of transmission characteristics for electrical signals.

In Fig. 5 and 6 For example, a frequency in [GHz] is plotted on a horizontal axis 26, and a transmission in [dB] is plotted on a vertical axis 28 for electrical signals. A first graph 30 in FIG Fig. 5 FIG. 12 illustrates the transmission 28 versus frequency 26 in common mode signal transmission (without phase shifting between the signals on the pairs of conductors 10, 12 and 14, 16) and a second graph 32 in FIG Fig. 5 FIG. 12 illustrates the transmission 28 versus frequency 26 in a differential mode signal (with phase shifting between signals on the pairs of conductors 10, 12 and 14, 16) for a conventional quad-core cable, respectively Fig. 3 , A third graph 34 in Fig. 6 FIG. 12 illustrates transmission 28 versus frequency 26 for common mode signal transmission (without phase shifting between the signals on the pairs of conductors 10, 12 and 14, 16) and a fourth graph 36 in FIG Fig. 6 Figure 4 illustrates the transmission 28 as a function of the frequency 26 in a differential mode signal (with phase shift between the signals on the conductor pairs 10, 12 and 14, 16) for a star quad cable according to the invention, respectively Fig. 4 , The Graphs 30, 32, 34 and 36 are each from simulations for the arrangement according to the Fig. 3 and 4 won.

How out Fig. 5 , second graph 32 can be seen occurs in a conventional star quad cable break in the transmission in push-pull at about 2.9 GHz. This burglary is no longer present in a star quad cable according to the invention, as seen from Fig. 6 , fourth graph 26 can be seen. This simulation result impressively shows the resounding and unexpected improvement in the electrical properties of the star quad cable according to the invention in the transmission of electrical signals. This improvement is already given here before damage or aging of the screen.

A further improvement of the electrical properties or the transmission characteristics of the star quad cable for electrical signals is achieved by at least individual shield wires 23 each following one of the conductors 10, 12, 14, 16 in parallel. In other words, at least individual shield conductors 23 are stranded with the same lay length s or the same stranding factor as the conductors 10, 12, 14, 16. This is exemplary of a shield core 23a in FIG Fig. 7 shown. In Fig. 7 also the stroke length s 46 is illustrated. The shield core 23a helically winds around the conductors 10, 12, 14, 16 through the stranding such that the shield core 23a extends parallel to the conductor 14. The exact relative arrangement between the shield wire 23a and the conductor 14 is off Fig. 2 seen. The shield core 23a winds around the conductors 10, 12, 14, 16 such that at each location in the cross-section of the quad-core cable the conductors 14 and the shield core 23a are on a common diagonal 19 and the shield core 23a on one side of the conductor 14 is arranged, which faces away from the square 17. By virtue of this arrangement of the shield core 23a, a shield current assigned to the conductor 14 can follow the conductor 14 without transition to another shield core 23. By avoiding transitions of the shielding current from one shielding core 23 to another, the electrical conduction of the shielding current across the shield 22 improves and overall the electrical properties and / or the transfer characteristic of the four-core cable for the transmission of electrical signals is improved. In particular, for example, results in a low Damping for the electrical useful signal transmitted by the star quad cable according to the invention.

The square 17 has, for example, a side length a 48 of 0.83 mm. This side length a corresponds to the distance of the centers of two adjacent conductors 10, 12, 14, 16. A location vector r _{Ader, n} in the coordinate system 40, 42 with the longitudinal axis of the star quad cable as z-direction for the n-th wire with n = [1 ... 4] is then given a free parameter t = [0 ... 1 ] for the z direction and over a strike length s $${\overrightarrow{r}}_{\mathit{Vein}.n}=\left(\begin{array}{c}\frac{a}{\sqrt{2}}\cdot \cos \left[\left(2\pi \cdot t\right)+\left(n-1\right)\cdot \frac{\pi }{2}\right]\\ \frac{a}{\sqrt{2}}\cdot \sin \left[\left(2\pi \cdot t\right)+\left(n-1\right)\cdot \frac{\pi }{2}\right]\\ s\cdot t\end{array}\right)$$

in dem Koordinatensystem 40, 42 mit der Längsachse des Sternvierer-Kabels als z-Richtung für eine n_Schirm-te Schirmader 23 bzw. 23a lautet dann mit einem freien Parameter t = [0... 1] für die z-Richtung und über eine Schlaglänge s $${\overrightarrow{r}}_{n_{\mathit{Schirm}}}=\left(\begin{array}{c}\frac{d_{\mathit{Schirm}}}{2}\cdot \cos \left[\left(2\pi \cdot t\right)+\left(n_{\mathit{Schirm}}-1\right)\cdot \mathrm{\Delta }\varphi \right]\\ \frac{d_{\mathit{Schirm}}}{2}\cdot \sin \left[\left(2\pi \cdot t\right)+\left(n_{\mathit{Schirm}}-1\right)\cdot \mathrm{\Delta }\varphi \right]\\ s\cdot t\end{array}\right)$$

wobei d_Schirm ein Durchmesser 50 einer Schirmader 23, 23a, n_Schirm = [1...N_Schirm], wobei N_Schrim eine Gesamtzahl der Schirmadern ist, und $\mathrm{\Delta }\varphi =\frac{\mathrm{z\pi }}{N_{\mathit{Schirm}}}$

ein Winkel 52 zwischen der Diagonalen 19 des zugeordneten Leiters, in dem dargestellten Beispiel des Leiters 14, und einer Geraden 60 durch den Ursprung 44 ist, auf der die jeweilige Schirmader 23 liegt. Für die Schirmader 23a ist beispielsweise Δϕ = O°. Mit $\mathrm{\Delta }\varphi =\frac{\mathrm{z\pi }}{N_{\mathit{Schirm}}}$

eingesetzt ergibt sich $${\overrightarrow{r}}_{n_{\mathit{Schirm}}}=\left(\begin{array}{c}\frac{d_{\mathit{Schirm}}}{2}\cdot \cos \left(2\pi \cdot \left[t+\frac{n_{\mathit{Schirm}}-1}{N_{\mathit{Schirm}}}\right]\right)\\ \frac{d_{\mathit{Schirm}}}{2}\cdot \sin \left(2\pi \cdot \left[t+\frac{n_{\mathit{Schirm}}-1}{N_{\mathit{Schirm}}}\right]\right)\\ s\cdot t\end{array}\right)$$

A corresponding location vector ${\overrightarrow{r}}_{n_{\mathit{umbrella}}}$

in the coordinate system 40, 42 with the longitudinal axis of the star quad cable as z-direction for a n _screen -th _screen wire 23 or 23a is then with a free parameter t = [0 ... 1] for the z-direction and over a strike length s $${\overrightarrow{r}}_{n_{\mathit{umbrella}}}=\left(\begin{array}{c}\frac{d_{\mathit{umbrella}}}{2}\cdot \cos \left[\left(2\pi \cdot t\right)+\left(n_{\mathit{umbrella}}-1\right)\cdot \mathrm{\Delta }\phi \right]\\ \frac{d_{\mathit{umbrella}}}{2}\cdot \sin \left[\left(2\pi \cdot t\right)+\left(n_{\mathit{umbrella}}-1\right)\cdot \mathrm{\Delta }\phi \right]\\ s\cdot t\end{array}\right)$$

where d _{screen is} a diameter 50 of a screen wire 23, 23a, n _screen = [1 ... N _screen ], where N _{scrim is} a total number of screen wires, and $\mathrm{\Delta }\phi =\frac{\mathrm{z\pi }}{N_{\mathit{umbrella}}}$

an angle 52 between the diagonal 19 of the associated conductor, in the illustrated example of the conductor 14, and a straight line 60 through the origin 44 on which the respective shield wire 23 lies. For the shield core 23a, for example, Δφ = 0 °. With $\mathrm{\Delta }\phi =\frac{\mathrm{z\pi }}{N_{\mathit{umbrella}}}$

used results $${\overrightarrow{r}}_{n_{\mathit{umbrella}}}=\left(\begin{array}{c}\frac{d_{\mathit{umbrella}}}{2}\cdot \cos \left(2\pi \cdot \left[t+\frac{n_{\mathit{umbrella}}-1}{N_{\mathit{umbrella}}}\right]\right)\\ \frac{d_{\mathit{umbrella}}}{2}\cdot \sin \left(2\pi \cdot \left[t+\frac{n_{\mathit{umbrella}}-1}{N_{\mathit{umbrella}}}\right]\right)\\ s\cdot t\end{array}\right)$$

Although the shield core 23a is preferred for guiding the shield current associated with the conductor 14, this shield current of the conductor 14 may also be guided by one of the two shield conductors 23 adjacent to the shield core 23a. Thus, should the shield core 23a be damaged due to bending or torsional loading, the shield current may still flow substantially parallel to the conductor 14 across the shield 22 along the shield conductors 23a without having to make a change to another shield core 23.

A lay length s 46 is for example 40 mm. A radius 54 of the screen 22 is, for example, r _screen = 1.5 mm. A diameter 56 of a wire 18 is for example d _wire = 0.48 mm. A diameter 58 of a conductor _shell 20 is for example d _Aderiso = a = 0.83 mm. The diameter 50 of a shield core 23, 23a is, for example, d _shield = 0.1 mm.

Optionally, a second screen (not shown) made of an electrically conductive material is additionally arranged radially on the outside of the screen 22. This second screen is thereby electrically conductively connected to the screen 22 on its radially inner side, so that electrical compensation currents can flow over the second screen. As a result, by means of the compensation currents, if necessary, manufacturing tolerances can be compensated which, for example, lead to the shield core 23a not being exactly parallel to the associated conductor 14 (FIG. Fig. 2 ) runs. By means of the equalizing currents over the second screen, aging phenomena or damage to the screen 22 can be compensated accordingly.

Claims (8)

1. Star-quad cable for transmitting electrical signals which has at least two pairs of electrical conductors (10, 12, 14, 16), each conductor (10, 12, 14, 16) having a core (18) made of an electrically conductive material and a conductor sheath (20) made of an electrically insulating material which surrounds the core (18) in a radial position, the conductors (10, 12, 14, 16) being arranged at the corners of a square in a cross-section of the star-quad cable, the conductors (10, 12, 14, 16) making up a pair being arranged at diagonally opposed corners of the square, four conductors (10, 12, 14, 16) at a time being twisted together in a star-quad arrangement with a predetermined lay factor, a shield (22) made of a electrically conductive material which surrounds the two pairs of conductors (10, 12, 14, 16) on the outside radially being placed in position, an additional insulator sheath (24) made of an electrically insulating material being arranged between the conductors (10, 12, 14, 16) and the shield (22), and the shield (22) being constructed from a mesh of individual shield cores, characterised in that at least one, and in particular four, shield cores or at least one, and in particular four, bundles of shield cores are twisted to surround the conductors (10, 12, 14, 16) in a radial position in such a way that at least one of the twisted shield cores or at least one of the bundles of shield cores extends substantially parallel to a respective core (18) of a conductor (10, 12, 14, 16) in the axial direction, a shield core or a bundle of shield cores on the one hand and a respective core (18) on the other hand extending in parallel to one another in the axial direction in such a way that the shield core or the bundle of shield cores and the core (18) lie on the same diagonal of the square at all points along the cross-section of the cable and the shield core or the bundle of shield cores is arranged on a side of the core (18) which is remote from the square.
2. Star-quad cable according to claim 1, characterised in that the shield cores or the bundles of shield cores are twisted with a lay factor which corresponds to a lay factor of the conductors (10, 12, 14, 16).
3. Star-quad cable according to at least one of the preceding claims, characterised in that the cores (18) are made of copper.
4. Star-quad cable according to at least one of the preceding claims, characterised in that a second shield which is conductively connected to the shield (22) electrically is arranged on the shield (22) outside it radially.
5. Star-quad cable according to claim 4, characterised in that the second shield takes the form of a sheath or foil made of an electrically conductive material.
6. Star-quad cable according to claim 4, characterised in that the second shield is constructed as a mesh of individual second shield cores.
7. Star-quad cable according to claim 6, characterised in that the second shield cores are twisted in the opposite direction to the cores of the shield (22).
8. Star-quad cable according to claim 7, characterised in that the second shield cores are twisted with a lay factor which corresponds to the lay factor of the cores of the shield.

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