CABLE FOR ELECTRICALLY TRANSMITTING DATA

Abstract

A cable (100; 200) for electrically transmitting data includes two insulated line wires (110, 111), each of which has an inner conductor (110-1, 111-1) and which are stranded together in order to form a stranded line pair. A first dielectricum (130, 230) at least partly surrounds the two line wires (110, 111), and is at least partly arranged on the outer surface of the insulated line wires (110, 111). An interior at least partly enclosed by the first dielectricum (130) is partly filled with the stranded line pair. A second dielectricum (150) at least partly surrounds the first dielectricum (130; 230). A shielding (160, 170, 180) at least partly surrounds the second dielectricum (150). The first dielectricum (130; 230) is arranged at at least a specified distance (A) to the shielding (160).

Claims

1. A cable (100; 200) for electrically transmitting data, having: two insulated line wires (110, 111), each of which has an inner conductor (110-1, 111-1) and which are stranded with one another to form a stranded line pair; a first dielectric (130; 230) which at least partly surrounds the two insulated line wires (110, 111), wherein the first dielectric (130) is arranged partly on outer surfaces of the insulated line wires (110, 111), and wherein an interior space at least partly enclosed by the first dielectric (130) is partly filled by the stranded line pair; a second dielectric (150) which at least partly surrounds the first dielectric (130; 230); and a shielding (160, 170, 180) which at least partly surrounds the second dielectric (150), wherein the first dielectric (130; 230) is at at least a predetermined distance (A) from the shielding (160).

2. The cable (100; 200) as claimed in claim 1, wherein the second dielectric (150) completely surrounds or encloses the first dielectric (130; 230) in the radial direction.

3. The cable (200) as claimed in claim 1, wherein the first dielectric (230) has an elliptical cross-sectional shape, wherein the elliptical cross-sectional shape extends within a plane which extends substantially orthogonal to a cable longitudinal axis.

4. The cable (200) as claimed in claim 3, wherein each insulated line wire (110, 111) has a circular cross-sectional shape with a geometric center, wherein the circular cross-sectional shape extends within a plane which extends substantially orthogonal to the cable longitudinal axis, the geometric centers of the insulated line wires (110, 111) are arranged on a major axis of the elliptical cross-sectional shape and symmetrically with respect to a minor axis of the elliptical cross-sectional shape.

5. The cable (200) as claimed in claim 3, wherein the elliptical cross-sectional shape has two opposing vertices along each of the major axis and the minor axis, the two vertices of the major axis form a path with a first predetermined length and the two vertices of the minor axis form a path with a second predetermined length, a ratio of the first predetermined length to the second predetermined length corresponds at least to 1.4 to 1, for example 2:1.

6. The cable (100) as claimed in claim 1, wherein the first dielectric (130) forms the interior space in a plane extending orthogonal to a cable longitudinal axis by two side portions arranged parallel to one another and two semicircular portions, in each case one semicircular portion is arranged at least partly along the outer surface of one of the insulated line wires (110, 111), and the two side portions arranged parallel to one another are arranged between the two semicircular portions and end therewith so as to form the interior space.

7. The cable (100; 200) as claimed in claim 1, wherein a strand lay length of the first dielectric (130; 230) corresponds to from 0.4 to 0.9, for example 0.7, of a strand lay length of the stranded line pair, or the strand lay length of the first dielectric (130; 230) corresponds to the strand lay length of the stranded line pair, or/and the first dielectric is formed in the form of a strip or an insulating film which is wound around the stranded line pair, the strip or the insulating film extends along a strip/insulating film direction of extent and has a width extending orthogonal to this strip/insulating film direction of extent, wherein the width of the first dielectric corresponds to from 0.2 to 0.7, for example from 0.3 to 0.65, of the strand lay length of the stranded line pair.

8. The cable (100; 200) as claimed in claim 1, wherein each line wire (110, 111) is at least partly surrounded by a third dielectric (110-2, 111-2) so as to insulate the line wires (110, 111) from one another, the third dielectric (110-2, 111-2) has a relative permittivity of from 1.2 to 2.5, for example from 1.4 to 2.3.

9. The cable (100; 200) as claimed in claim 8, wherein the third dielectric (110-2, 111-2) has a relative permittivity which corresponds to a relative permittivity of the second dielectric (150).

10. The cable (100; 200) as claimed in claim 1, wherein the first dielectric (130; 230) has a relative permittivity of from 1.8 to 3.5, for example from 2.0 to 3.3, or/and the predetermined distance (A) is at least 0.15 mm, for example from 0.3 to 0.6 mm.

11. The cable (100; 200) as claimed in claim 1, wherein the second dielectric (150) has a relative permittivity of from 1.3 to 2.8, for example from 1.5 to 2.5, or/and wherein the second dielectric (150) is formed by extrusion.

12. The cable (100; 200) as claimed in claim 1, wherein the shielding has a plastics foil (160) with a metal-clad inner and/or outer side, which is formed on the outer surface of the second dielectric (150), or/and the shielding further has a braided shield (170), which is arranged on the metal-clad outer side or on the outer side of the plastics foil (160) without metal cladding, and the braided shield (170) covers at least from 50 to 92%, for example from 75 to 89%, of the outer side of the plastics foil (160).

13. The cable (100; 200) as claimed in claim 1, wherein the shielding (160, 170) has a layer (180) formed by extrusion, which at least partly surrounds at least the plastics foil (160), or/and the plastics foil (160) consists of polypropylene or polyethylene terephthalate, or/and the braided shield (170) consists of copper wires running parallel to one another.

14. The cable (100; 200) as claimed in claim 1, wherein the second dielectric (150) consists of polypropylene, or/and the first, the second or/and the third dielectric (130, 150, 110-2, 111-2) is an insulating film.

15. The cable (100; 200) as claimed in claim 1, wherein the two insulated line wires (110, 111) are stranded in a strand lay direction with a strand lay length so as to form the stranded line pair, the first dielectric (130; 230) is wound around the stranded line pair in or contrary to the strand lay direction.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0040] FIG. 1 shows a cross-section through a cable for electrically transmitting data according to a first exemplary embodiment; and

[0041] FIG. 2 shows a cross-section through a cable for electrically transmitting data according to a second exemplary embodiment.

DETAILED DESCRIPTION

[0042] Components and features which are comparable or identical and have the same effect are in each case provided with the same reference numerals in the figures.

[0043] FIG. 1 shows, schematically, a first exemplary embodiment of a cable 100 for electrically transmitting data in the form of a cross-section through the cable 100. The cross-section through the cable 100 extends within a plane extending orthogonal to a cable longitudinal axis of the cable 100.

[0044] The cable 100 has two insulated line wires 110, 111 which are stranded with one another and form a stranded line pair. The two insulated line wires 110, 111 are surrounded or enclosed by a first dielectric 130. The first dielectric 130 has a substantially constant wall thickness. If the first dielectric 130 is wound around the line wires 110, 111, as will be described below, the first dielectric 130 can have double the wall thickness in overlapping regions. The individual windings can thereby partly overlap, which is to be understood as being an overlapping region. The wall thickness is a length which extends within the plane of the drawing or within the plane defined above and which indicates a distance between two opposite portions of an inner and outer side/surface of the first dielectric 130. The wall thickness is the shortest connection from the inner side to the outer side. The first dielectric 130 forms/delimits an interior space in which the two insulated line wires 110, 111 are arranged. As is shown in FIG. 1, the two insulated line wires 110, 111 occupy only part of the interior space and a free space 140 remains between the insulated line wires 110, 111 and the first dielectric 130. The free space 140 can be filled with gas/gas-filled, for example with air. Signals are conducted through the insulated line wires 110, 111. The signals generate one or more fields.

[0045] The first dielectric 130 shown in FIG. 1 has a cross-sectional shape which is similar to an ellipse. The cross-sectional shape thereby extends in a plane extending orthogonal to the cable longitudinal axis. The cross-sectional shape of the first dielectric 130 has two side portions arranged substantially in parallel and two substantially semicircular portions. The two parallel side portions are arranged opposite one another and are spaced apart from one another by a predetermined distance from a cable midpoint of the cable. Furthermore, in each case one of the two semicircular portions is arranged at least partly along the outer surface of one of the two line wires. A radius of a semicircular portion thereby corresponds substantially to a radius of the circular cross-section of the insulated line wires 110, 111 or is only slightly larger than that radius, so that the semicircular portion at least partly rests against the outer surface of the insulated line wires 110, 111 or encloses or surrounds the insulated line wires. The two parallel side portions are arranged between the two semicircular portions and connect the respective ends of the semicircular portions so as to form a continuous jacket for the two line wires 110, 111. The interior space of the first dielectric 130 is thus formed in cross-section.

[0046] The cable 100 further has a second dielectric 150 in the form of an intersheath which at least partly surrounds the first dielectric 130. The first dielectric 130 has an inner surface which faces the two insulated line wires 110, 111, and an outer surface. The outer surface of the first dielectric 130 faces an inner surface of the second dielectric 150. According to the cross-section shown in FIG. 1, the second dielectric 150 completely surrounds the first dielectric 130. The second dielectric 150 has a substantially circular cross-section or a substantially circular outer contour, wherein the first dielectric 130 is arranged together with the insulated line wires 110, 111 substantially centrally within the second dielectric 150. Owing to the elliptically similar, that is to say similar to an ellipse, cross-sectional shape of the first dielectric 130, the second dielectric 150 has a varying wall thickness so as to form the circular cross-section.

[0047] The cable 100 further has a shielding 160, 170, 180 which at least partly surrounds or encloses the second dielectric 150. According to the cross-section shown in FIG. 1, the shielding 160, 170, 180 completely surrounds the second dielectric 150. An outer surface of the second dielectric 150 faces an inner surface of the shielding 160, 170, 180. In particular, the shielding has a plastics foil 160, which at least partly encloses the outer surface of the second dielectric 150. The plastics foil 160 leads to improved stability of the cable 100. The plastics foil 160 has a metal-clad inner and/or outer side or surface.

[0048] By the provision of the second dielectric 150, a direct coupling between the line wires 110, 111 is increased in relation to a coupling between the line wires 110, 111 and the second dielectric 150. Thus, more field lines close without the involvement of the shielding 160, 170, 180, and the field strength in the part of the interior space that is not filled by the line wires 110, 111 is increased.

[0049] The shielding further has a braided shield 170 which is arranged on the outer surface of the plastics foil 160 and at least partly surrounds or encloses it. The braided shield 170 thereby covers at least from 50 to 92%, for example from 75 to 89%, of the outer side/outer surface of the plastics foil 160. The shielding further has a layer 180 formed by extrusion, which forms an outermost layer of the cable 100. The layer 100 at least partly surrounds the plastics foil 160. According to FIG. 1, the layer 180 surrounds an outer surface of the braided shield 170, wherein an inner surface of the braided shield 170 faces the outer surface of the plastics foil 160. Thus, the braided shield 170 is arranged between the plastics foil 160 and the layer 180. The plastics foil 160 can consist of polypropylene or polyethylene terephthalate. The braided shield 170 can consist of copper wires running parallel to one another. The copper wires running parallel to one another can further be braided with one another so as to form the braided shield 170.

[0050] As is shown in FIG. 1, the first dielectric 130 is at a predetermined distance A from the plastics foil 160. This predetermined distance A is greater than zero. In other words, a minimum wall thickness of the second dielectric 150 corresponds to the predetermined distance A. According to FIG. 1, the two midpoints of the line wires 110, 111 are arranged on a path which runs parallel to the two parallel portions of the first dielectric 130 and is arranged between these two parallel portions. In order to achieve a circular cross-sectional shape of the second dielectric 150, the wall thickness along this path corresponds to the predetermined distance A. The wall thickness of the second dielectric 150 is greatest along a path which is orthogonal to that path and extends through the midpoint of the cable 100. The predetermined distance A is at least 0.15 mm, for example from 0.3 to 0.6 mm. By spacing the plastics foil 160 apart from the first dielectric 130 by the predetermined distance A, improved capacitive decoupling of the two line wires 110, 111 from the shielding 160, 170, 180, which functions as an electrical reference, is achieved. The above-described sizes, in particular the wall thickness, relate to the cross-sections shown in the figures, which do not show any overlapping of the individual dielectrics or shields. It will be appreciated by the person skilled in the art that the wall thickness can double in overlapping regions.

[0051] Each of the line wires 110, 111 further has an inner conductor 110-1, 111-1 and a third dielectric 110-2, 111-2. In each line wire 110, 111, the third dielectric 110-2, 111-2 at least partly encloses or surrounds the inner conductor 110-1, 111-1. The third dielectric 110-2, 111-2 can be in the form of an insulating sleeve. By means of the third dielectric 110-2, 111-2, the two inner conductors 110-1, 111-1 and thus the two line wires 110, 111 are insulated from one another.

[0052] FIG. 2 shows a cable 200 in which, in contrast to the cable 100 of FIG. 1, the first dielectric 230 has a substantially elliptical cross-sectional shape. This elliptical cross-sectional shape extends in a plane orthogonal to the cable longitudinal axis. Similarly to the first dielectric 130 of the cable 100 in FIG. 1, the first dielectric 230 of the cable 200 has the two line wires 110, 111 and a free space 240. The elliptical cross-sectional shape has a major axis and a minor axis which are orthogonal to one another. An ellipse generally has four vertices, wherein in each case two vertices are arranged on the major axis and two vertices are arranged on the minor axis. According to FIG. 2, the two vertices of the major axis are spaced further apart from the origin, or the midpoint, of the elliptical cross-sectional shape than the two vertices of the elliptical cross-sectional shape on the minor axis. The geometric centers of the line wires 110, 111 or of the inner conductors 110-1, 111-1 are arranged on the major axis and are at the same distance from the midpoint of the elliptical cross-sectional shape. Thus, the centers of the line wires 110, 111 are arranged symmetrically with respect to the minor axis. A first path which connects the two vertices on the major axis has a first predetermined length, and a second path which connects the two vertices on the minor axis has a second predetermined length. A specific form of the elliptical cross-sectional shape is formed with a ratio of the first predetermined length to the second predetermined length of at least 1.4 to 1, for example 1.7 to 1, and in particular 2 to 1. With such a form of the elliptical cross-sectional shape, the fields generated by the signals in the line wires 110, 111 are guided virtually without loss over the shortest path.

[0053] The following aspects of the invention can apply both to the cable 100 according to FIG. 1 and to the cable 200 according to FIG. 2.

[0054] The line wires 110, 111 of the cable 100, 200 can be stranded with one another with a predetermined strand lay length and strand lay direction. A strand lay length of the first dielectric 130, 230 can correspond to from 0.4 to 0.9, for example 0.7, of a strand lay length of the line wires 110, 111. For example, the strand lay length of the first dielectric 130, 230 can correspond to 0.43 of the strand lay length of the insulated wires 110, 111. In other words, a (foil) pitch of the first dielectric 130, 230 can correspond to from 0.4 to 0.9, for example 0.7, of the strand lay length or substantially to the strand lay length of the insulated line wires 110, 111. For example, the pitch of the first dielectric 130, 230 can correspond to 0.43 of the strand lay length of the insulated line wires 110, 111. By means of such a ratio of the strand lay lengths, a cross-sectional shape similar to the ellipse or an elliptical cross-sectional shape of the cross-section of the first dielectric 130, 230 is achieved in a particularly simple manner during production. The first dielectric 130, 230 can be wound around the two insulated line wires 110, 111 in or contrary to the strand lay direction.

[0055] The first dielectric 130, 230 can be an insulating film which has a strip/insulating film direction of extent and a width extending orthogonal thereto. Orthogonal to the width and the strip/insulating film direction of extent, the insulating film has a constant thickness, which, however, is small compared to a length along the strip/insulating film direction of extent and the width. The width can correspond to from 0.2 to 0.7, for example from 0.3 to 0.65, of the strand lay length of the line wires 110, 111. With these parameters, the first dielectric 130, 230 at least partly encloses the outer surface of the line wires 110, 111 and thus is substantially supported on this part-surface. The first dielectric 130 can be wound around the line wires 110, 111 such that overlapping regions of the first dielectric 130 are formed between the individual turns of the first dielectric 130, in order thus to form an interior space 140, 240 which is closed when viewed in cross-section.

[0056] The third dielectric 110-2, 111-2 can have a relative permittivity of from 1.2 to 2.5, for example from 1.4 to 2.3, or/and a loss factor of 5×10.sup.e−4. A reduced transmission loss of the cable 100, 200 can be achieved by means of these values.

[0057] The third dielectric 110-2, 111-2 can have a relative permittivity which corresponds to the relative permittivity of the second dielectric 150. Furthermore, the predetermined distance A and the relative permittivity are significant for the capacitance between the line wires 110, 111, and low values are to be strived for. Such a low capacitance value is achieved in particular in the case of a combination with a predetermined distance A of 0.15 mm, for example from 0.3 to 0.6 mm.

[0058] The first dielectric 130, 230 can have a relative permittivity of from 1.8 to 3.5, for example from 2.0 to 3.3.

[0059] The second dielectric 150 can have a relative permittivity of from 1.3 to 2.8, in particular from 1.5 to 2.5. Alternatively or additionally, the second dielectric 150 can be formed by extrusion. Additionally or alternatively, the second dielectric 150 can consist of polypropylene.

[0060] The first, the second or/and the third dielectric 130, 230, 150, 110-2, 111-2 can be an insulating film.

[0061] It will be appreciated that the exemplary embodiments explained hereinbefore are not conclusive and do not limit the subject-matter disclosed herein. In particular, it will be apparent to the person skilled in the art that he can combine the described features with one another as desired and/or can omit different features without departing from the subject-matter disclosed herein.