CABLE SHIELDING

Description

[0001] The present invention relates to a cable shield and an electrical line with such a cable shield.

[0002] A shield is an electrically conductive protective covering that surrounds a device, a space, or a transmission medium, such as a cable. To distinguish between shielding for devices, one often refers to a device shield, a shielding for a space is referred to as a room shield, and a shielding for a transmission medium is referred to as a cable shield.

[0003] Cable shielding is used in transmission media such as electrical conductors. Electrical conductors conduct electricity for a variety of purposes. A current flowing in an electrical conductor always generates a magnetic field that accompanies the current flow. In general, it is desirable to reduce the effects of such a magnetic field on other devices and equipment, as this can lead to unwanted malfunctions in electrical or electronic equipment. This is often summarized under the term electromagnetic compatibility (EMC). On the one hand, shielding reduces electromagnetic interference on the signal-carrying conductors or in the devices. On the other hand, shielding also reduces stray radiation from a cable or the devices to the environment.

[0004] When it comes to cable shielding, a distinction is made between foil and braided shielding, and a combination of both. Foil shielding is more efficient at higher frequencies, while braided shielding is more effective at lower frequencies. Foil and braided shielding can also be combined, for example, laid in alternating layers. The quality of the shielding depends on the coverage and is expressed in the shield attenuation or shielding efficiency. This is directly reflected in the coupling resistance, also known as shield coupling impedance or transfer impedance. The transfer impedance is the ratio between the high-frequency (HF) interference voltage induced on a data line and the causing RF interference current flowing through the shield. The lower the transfer impedance, the better the shielding effect. In addition to the cable shields mentioned above, there are also special cables in which the shield is a copper tube. These cables are characterized by a very high shielding efficiency.

[0005] In addition to stress related to their electrical and / or magnetic properties, cable shields are also subjected to mechanical stress. In braided shields, the wires of a braid that are subjected to movement experience relative movement with associated friction. Furthermore, these wires are subjected to tensile and shear stresses. This results in a limited service life of the wires and thus of the braid. A shield with counter-rotating wire winding has a longer mechanical service life. However, the shield can shift, sometimes resulting in nests and / or holes. As explained above, this has a negative impact on the electrical properties.

[0006] EP 2 725 585 A1 relates to a cable having a pair of insulated conductors or a bundle of four insulated conductors arranged within a sheath. The pair or bundle of four conductors are wound helically along one winding direction. The pair or bundle of four insulated conductors are surrounded by shielding wires arranged in a helix. A plurality of the shielding wires arranged in a helix extend along another winding direction opposite to the previous winding direction.

[0007] GB 339 425 A relates to a conduit tube having braided wires arranged in opposing open spirals on its outer surface. The braid formed is embedded in the tube by spot welding or soldering at evenly spaced intersections of the wires.

[0008] CN 109102986 A relates to a coil wound from a cable comprising multiple strands of strip conductors. The strip conductor strands extend spirally along a length of the cable at varying pitch angles to one or more other strands. The strip conductor strands are interwoven over and under each other along the length of the cable.

[0009] There is therefore a need for improved cable shielding. In particular, there is a need for a cable shield that is more resistant to mechanical stress and, consequently, has more stable electrical properties.

[0010] According to a first aspect of the invention, a cable shield is proposed. The cable shield has a first wire winding and a second wire winding. The first wire winding has a plurality of turns. The first wire winding is wound in a first direction with a first pitch around a longitudinal axis. The second wire winding has a plurality of turns. The second wire winding is wound in a second direction, deviating from the first direction, with a second pitch around the longitudinal axis. Turns of the plurality of turns of the first wire winding and corresponding turns of the plurality of turns of the second wire winding each intersect at a first intersection point.The turns of the plurality of turns of the first wire winding and the corresponding turns of the plurality of turns of the second wire winding each intersect at the first intersection point such that a plurality of first intersection points of the first wire winding and the second wire winding are present in the direction of the longitudinal axis. The course of the plurality of first intersection points in the direction of the longitudinal axis is at least approximately helical.

[0011] The helical configuration can also be referred to as a screw-shaped, spiral, or helical configuration. The helical configuration of the first crossing points (which can also be referred to as overlap points) ensures good / increased stability against drag, torsional, and alternating bending movements. The longitudinal axis can be the longitudinal axis of the cable shield (the braided shield). The cable shield can be at least approximately cylindrical. The crossing points can therefore run helically along the cable shield (the braided shield).

[0012] The first wire winding may comprise at least one first wire. The at least one first wire may be wound around the longitudinal axis in such a way that the first wire winding extends helically around the longitudinal axis. The second wire winding may comprise at least one second wire. The at least one second wire may be wound around the longitudinal axis in such a way that the second wire winding extends helically (helically / spirally / coil-like) around the longitudinal axis.

[0013] In cable shielding, the arrangement of the first wire winding and the second wire winding relative to each other can be considered a combination of wire braiding and braiding, due to the wires being intertwined at least once per turn, with the two wire windings intertwined at least once per turn. In this respect, the cable shielding can be described as a two-layer wire braiding with helical crossing points / helical crossing.

[0014] One turn of the first second wire winding can be understood as one complete revolution in the circumferential direction from a starting position to an end position. In view of the first pitch, the starting position and the end position do not have to match in the direction of the longitudinal axis. The starting position and the end position only have to match in the circumferential direction around the longitudinal axis for one turn to result. In the direction of the longitudinal axis, the starting position and end position will differ from one another if the first pitch is not equal to 0. One turn of the second wire winding can be understood as one complete revolution in the circumferential direction from a starting position to an end position. In view of the second pitch, the starting position and the end position do not have to match in the direction of the longitudinal axis.The starting and ending positions only need to coincide in the circumferential direction around the longitudinal axis to create a coil. In the direction of the longitudinal axis, the starting and ending positions will differ if the second pitch is not equal to 0.

[0015] Accordingly, "corresponding turns" means that one turn of the first wire winding and one turn of the second wire winding correspond to each other if they are at least almost identical in position and, for example, at least so almost identical that they can cross each other in their normal course when wound in opposite directions.

[0016] The turns of the plurality of turns of the first wire winding and the corresponding turns of the plurality of turns of the second wire winding can each intersect at a second intersection point. The turns of the plurality of turns of the first wire winding and the corresponding turns of the plurality of turns of the second wire winding can each intersect at a second intersection point such that a plurality of second intersection points of the first wire winding and the second wire winding are present in the direction of the longitudinal axis. The course of the plurality of second intersection points in the direction of the longitudinal axis can be at least approximately helical.

[0017] The extension of the plurality of first crossing points in the direction of the longitudinal axis and the extension of the plurality of second crossing points in the direction of the longitudinal axis can be at least nearly parallel to each other. Consequently, two at least nearly parallel helices (screws / spirals / coils) of crossing points can result.

[0018] Turns of the plurality of turns of the first wire winding and corresponding turns of the plurality of turns of the second wire winding can each intersect at a plurality of intersection points. The turns of the plurality of turns of the first wire winding and corresponding turns of the plurality of turns of the second wire winding can each intersect at a plurality of intersection points such that a plurality of intersection points of the first wire winding and the second wire winding are present in the direction of the longitudinal axis. The respective course of the plurality of intersection points in the direction of the longitudinal axis can each be at least approximately helical. The respective course of the plurality of intersection points in the direction of the longitudinal axis can run at least approximately parallel to one another.

[0019] The course of the plurality of intersection points in the direction of the longitudinal axis can run at least approximately parallel to one another. In other words, a helical course of a plurality of first intersection points can run parallel to a helical course of a plurality of second intersection points and, if appropriate, a helical course of a plurality of third intersection points, etc.

[0020] The first pitch and the second pitch can be the same. The first direction of the first wire winding and the second direction of the second wire winding differ from each other. The first direction and the second direction can be at least nearly opposite to each other. In this respect, the first wire winding and the second wire winding can be referred to as counter-rotating / counter-rotating wire windings. Accordingly, the first wire winding and the second wire winding can run in opposite directions and with the same pitch.

[0021] In general, the first wire winding and the second wire winding can intersect at their intersection points such that they are interwoven at the intersection points. This can provide a counter-rotating braid, i.e., a braid of two opposing wire windings.

[0022] The first wire winding and the second wire winding can, for example, run symmetrically to a plane through the longitudinal axis of the cable shielding. The first wire winding and the second wire winding can, as seen in the cross-section of the cable shielding, be arranged symmetrically to one another, e.g. symmetrically to the longitudinal axis of the cable shielding. The first wire winding can have one or more first wires or consist of one or more first wires. The second wire winding can have one or more second wires or consist of one or more second wires. In other words, a single first wire or a first wire bundle can form the first wire winding and a single second wire or a second wire bundle can form the second wire winding.

[0023] The helical intersections / overlaps increase the stability of the cable shield against drag, torsional, and / or alternating bending movements. Cable shielding according to the first aspect can therefore increase the service life of a cable shield under mechanical stress in two or three dimensions. This is accompanied by improved electrical properties (i.e., better electrical performance, e.g., with regard to EMC, leakage currents, etc.) over the service life of the cable shield.

[0024] According to a second aspect, an electrical cable is proposed. The electrical cable comprises at least one electrical conductor and a cable shield arranged around the electrical conductor according to the first aspect.

[0025] Shielding significantly reduces the measurable magnetic field of the electrical conductor compared to conventional unshielded conductors. Furthermore, the cable shielding is mechanically stable. Furthermore, a cable sheath / outer sheath can be arranged around the cable shielding.

[0026] Although some of the aspects and details described above have been described with respect to the cable shielding according to the first aspect, these aspects can also be implemented in a corresponding manner in the cable according to the second aspect.

[0027] The present disclosure will be further explained with reference to figures. These figures schematically show: Figure 1a shows a cable shielding according to an example; Figure 1b shows a cable shielding according to a possible embodiment of the present invention.

[0028] Specific details are set forth below, but are not limited thereto, in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that the present disclosure may be utilized in other embodiments that may differ from the details set forth below.

[0029] Figure 1ashows schematically a cable shield, more precisely a braided shield 1 for a cable, according to an example which does not fall under the wording of the claims, but facilitates the understanding of the invention. The braided shield 1 has a first wire winding 2 which extends spirally in a first direction of rotation with a first pitch in the direction of a longitudinal axis 1a of the braided shield 1. In other words, viewed from the lower end of the braided shield 1, i.e. in the direction of the arrow of the longitudinal axis 1a, the first wire winding 2 screws upwards in an anti-clockwise direction with a first pitch. The braided shield 1 has a second wire winding 3 which extends spirally in a second direction of rotation with a second pitch in the direction of the longitudinal axis 1a of the braided shield 1. In other words, viewed from the lower end of the braided shield 1, i.e.in the direction of the arrow of the longitudinal axis 1a, the second wire winding 3 screws upwards clockwise with a second pitch. In the example from . Figure 1a the first slope corresponds to the second slope.

[0030] As in Figure 1a As can be seen, one turn of the first wire winding 2 and one turn of the second wire winding 3 overlap at one point. This point is referred to as the crossing point 4 or overlap point. In the example from Figure 1a the two wire windings 2, 3 are intertwined at the intersection point 4. Since each of the wire windings 2, 3 has several turns in the direction of the longitudinal axis 1a, even with one intersection point per turn, several such intersection points exist in the direction of the longitudinal axis 1a. In the example from Figure 1aIt can be seen that these crossing points lie on a straight line 5 that runs parallel to the direction of the longitudinal axis 1a. The two wire windings 2, 3 form two layers due to the interweaving and can therefore also be referred to as a two-layer wire winding and, due to the parallelism of the crossing points to the longitudinal axis 1a, as a two-layer wire winding with axial crossing.

[0031] The wires / wire windings 2, 3 of the braid / braid shield 1 made of Figure 1a experience a relative movement with accompanying friction to each other when they are subjected to movement. Furthermore, these wires / wire windings 2, 3 experience tensile and shear loads. This results in a limited service life of the wires / wire windings 2, 3 and thus of the braid / braid shield 1. Although a braid shield 1 made of Figure 1aWith the oppositely oriented wire winding shown, the braided shield 1 has a relatively high mechanical durability and a longer mechanical durability than conventional braids, for example, made of wires with the same orientation. However, the braided shield 1 can shift, or more precisely, the wires of the braided shield 1 can shift, forming nests and holes, for example. This has a negative impact on the electrical properties of the braided shield 1.

[0032] Figure 1b shows schematically a cable shielding, more precisely a braided shielding 10 for a cable, according to an embodiment with improved properties compared to the cable shielding of Figure 1a. The braided shield 10 has a first wire winding 20 which extends spirally in a first direction of rotation with a first pitch in the direction of a longitudinal axis 10a of the braided shield 10. In other words, viewed from the lower end of the braided shield 10, i.e., in the direction of the arrow of the longitudinal axis 10a, the first wire winding 20 screws upwards in a counterclockwise direction with a first pitch. The braided shield 10 has a second wire winding 30 which extends spirally in a second direction of rotation with a second pitch in the direction of the longitudinal axis 10a of the braided shield 10. In other words, viewed from the lower end of the braided shield 10, i.e., in the direction of the arrow of the longitudinal axis 10a, the second wire winding 30 screws upwards in a clockwise direction with a second pitch. In the example from Figure 1bthe first pitch corresponds to the second pitch, ie each individual complete turn of the wire windings 20, 30 covers the same distance W in the direction of the longitudinal axis 10a. One turn describes one complete revolution of a wire of the respective wire winding 20, 30.

[0033] As in Figure 1b As can be seen, one turn of the first wire winding 20 and one turn of the second wire winding 30 overlap at one point. This point is referred to as the crossing point 40 or overlap point. In the example from Figure 1b the two wire windings 20, 30 are also intertwined at the intersection point 40. Since each of the wire windings 20, 30 has several turns in the direction of the longitudinal axis 10a, even with one intersection point per turn, several such intersection points 40 exist in the direction of the longitudinal axis 10a. In the example from Figure 1bIt can be seen that these crossing points 40 extend in the form of a helix 50 or spiral, ie, they do not form a straight line parallel to the direction of the longitudinal axis 10a. The two wire windings 20, 30 form two layers, so to speak, due to the interweaving and can therefore also be referred to as a two-layer wire covering and, due to the helical shape 50 of the crossing points 40, as a two-layer wire covering with a helical crossing.

[0034] In Figure 1bFor the sake of simplicity and clarity, only one crossing point 40 is shown per turn, more precisely per turn of the wire winding 20 and corresponding turn of the wire winding 30. However, a turn of the wire winding 20 and a corresponding turn of the wire winding 30 can cross at more than one point, i.e. at several points, i.e. they can each have several crossing points at which they are intertwined. For example, the wire winding 20 and the wire winding 30 are intertwined not just once but twice or possibly several times at one or more of their turns, e.g. at each of their turns, and accordingly have a first crossing point 40, a second crossing point and possibly further crossing points per turn. In this case, there are a plurality of first crossing points 40, a plurality of second crossing points and possibly a plurality of further crossing points in the direction of the longitudinal axis 10a.The plurality of first crossing points 40 can be described by a first helix / spiral 50 in the direction of the longitudinal axis 10a. The plurality of second crossing points can be described by a second helix / spiral in the direction of the longitudinal axis 10a, which runs parallel to the first helix / spiral 50. The plurality of further crossing points can be described by a further helix / spiral in the direction of the longitudinal axis 10a, which runs parallel to the first helix / spiral 50 and the second helix / spiral.

[0035] The information relating to Figure 1b The braided shielding 10 with helical overlapping points 40 described is more stable against drag, torsional and bending movements than the one with respect to Figure 1adescribed braided shielding 1 with axially running overlap points 4. The braided shielding 10 provides a shielding as a combination of wire braiding and braiding, which, per winding pair, is interwoven with itself at only one point on the circumference or at several points on the circumference. The interwoven point(s) run / run helically along the longitudinal axis 10a, such as the product axis, of the braided shielding 10. This increases the service life of the shielding 10 of cables under mechanical stress in two or three dimensions. This also results in better electrical properties (i.e., better electrical performance) over the service life (e.g., with regard to EMC, leakage currents, etc.).

Claims

1. Cable shielding (10) comprising: a first wire winding (20) with a plurality of turns, wherein the first wire winding (20) is wound in a first direction with a first pitch about a longitudinal axis (10a); a second wire winding (30) with a plurality of turns, wherein the second wire winding (30) is wound in a second direction, which is different from the first direction, with a second pitch about the longitudinal axis (10a); wherein turns of the plurality of turns of the first wire winding (20) and corresponding turns of the plurality of turns of the second wire winding (30) cross in each case at a first crossing point (40) such that a plurality of first crossing points (40) of the first wire winding (20) and of the second wire winding (30) is present in the direction of the longitudinal axis (10a) and the plurality of first crossing points (40) runs at least approximately helically in the direction of the longitudinal axis (10a).

2. Cable shielding (10) according to claim 1, wherein the turns of the plurality of turns of the first wire winding (20) and the corresponding turns of the plurality of turns of the second wire winding (30) cross in each case at a second crossing point such that a plurality of second crossing points of the first wire winding (20) and of the second wire winding (30) is present in the direction of the longitudinal axis (10a) and the plurality of second crossing points (30) runs at least approximately helically in the direction of the longitudinal axis (10a).

3. Cable shielding (10) according to claim 1 or 2, wherein turns of the plurality of turns of the first wire winding (20) and corresponding turns of the plurality of turns of the second wire winding (30) cross in each case at several crossing points such that a plurality of several crossing points of the first wire winding (20) and of the second wire winding (30) is present in the direction of the longitudinal axis (10a) and the plurality of several crossing points runs respectively at least approximately helically in the direction of the longitudinal axis (10a) in each case.

4. Cable shielding (10) according to any one of claims 1 to 3, wherein the plurality of several crossing points runs respectively at least approximately parallel to one another in the direction of the longitudinal axis (10a).

5. Cable shielding (10) according to any one of claims 1 to 4, wherein the first pitch and the second pitch have the same value.

6. Cable shielding (10) according to any one of claims 1 to 5, wherein the first direction and the second direction are at least virtually opposed to one another.

7. Electric cable comprising: at least one electrical conductor; and a cable shielding (10) according to any one of claims 1 to 6 arranged around the electrical conductor.