WO2019179567A1

WO2019179567A1 - Coaxial line, measuring assembly, and method for measuring a torsion of a coaxial line

Info

Publication number: WO2019179567A1
Application number: PCT/DE2019/100245
Authority: WO
Inventors: Bernd Janssen; Erwin Köppendörfer; Markus Schill
Original assignee: Leoni Kabel Gmbh
Priority date: 2018-03-19
Filing date: 2019-03-18
Publication date: 2019-09-26
Also published as: DE102018204178B3

Abstract

The invention relates to a coaxial line which is designed as a torsion sensor and has an inner conductor and an outer conductor for this purpose. An intermediate space is formed between the outer conductor and the inner conductor, wherein a dielectricum is arranged in the intermediate space. The inner conductor and the outer conductor are arranged at a distance from each other, and an impedance is produced as a result of the distance and the dielectricum. The outer conductor is deformable such that a torsion leads to a deformation of the outer conductor and thus to a change in the distance and to a change in the impedance. The invention additionally relates to a measuring assembly comprising such a coaxial line and to a method for measuring a torsion of such a coaxial line.

Description

Coaxial line, measuring arrangement and method for measuring a torsion of a coaxial line

The invention relates to a coaxial line, a measuring arrangement with such a coaxial line and a method for measuring the torsion of a corresponding coaxial line

A coaxial line generally includes an inner conductor and an outer conductor disposed about the inner conductor. Such a coaxial line finds use, for example, as a signal line or for data transmission.

Depending on the field of application, the coaxial line is exposed to more or less mechanical loads. These loads are particularly great when the coaxial line connects two mutually movable components, in particular machine parts, for example individual elements of a robot arm. Typical mechanical loads during operation are then tensile and elongated loads, bending loads and torsional loads, ie loads due to twisting. Frequently, the loads occur repeatedly, so over time the coaxial line sometimes wears out and may even be destroyed. Examples of destruction include breakage of the inner or outer conductor. In any case, there is a risk of performance degradation, i. the line no longer fulfills the intended task or no longer completely.

Analogous to the mechanical load of a coaxial line itself, corresponding loads also generally result for similarly elongated, elastic or movable and moving connecting parts which connect two mutually movable components. Examples of such a connecting part are

Hoses, other media guides, cable drag chains, springs or the like. Even such parts wear due to the aforementioned loads. Destruction or at least damage, especially of a coaxial line and in general of a moving connection part, usually leads to a malfunction of the affected system, which is why it is desirable to be able to recognize corresponding wear prematurely.

Against this background, it is an object of the invention to provide a coaxial line, which is designed as a torsion sensor and by means of which a torsion is measurable. In particular, the torsion should not only be measurable locally, but also straight along an elongate course of the conduit. In addition, the torsion should not be measurable only once but recurrently. The torsion should also during the intended use of the coaxial line, i. be measurable accordingly during operation. Furthermore, a measuring arrangement with such a coaxial line and a method for measuring a torsion of such a coaxial line are to be specified.

The object is achieved by a coaxial line, which is designed as a torsion sensor and this has an inner conductor and an outer conductor, wherein between the outer conductor and the inner conductor, a gap is formed, in which a dielectric is arranged, wherein the inner conductor and the outer conductor in one Spaced apart, resulting in an impedance due to the distance and the dielectric, wherein the outer conductor is deformable, so that a torsion leads to a deformation of the outer conductor and thus to a change in the distance and to a change in the impedance. Preferably, the dielectric is additionally deformable. The dielectric is generally a solid and in particular a preferably elastically deformable solid.

Furthermore, the object is achieved by a measuring arrangement which has a coaxial line and a measuring unit, wherein the coaxial line is designed as a torsion sensor and for this purpose has an inner conductor and an outer conductor, wherein a gap is formed between the outer conductor and the inner conductor in which a dielectric is arranged, wherein the inner conductor and the outer conductor are spaced apart from one another at a distance, wherein Due to the distance and the dielectric, an impedance results, wherein the outer conductor is deformable, so that a torsion leads to a deformation of the outer conductor and thus to a change of the distance and to a change in the impedance, wherein the measuring unit is designed for measurement the impedance of the line, the line having a terminal for connection to the measuring unit.

In addition, the object is achieved by a method for measuring a torsion of a coaxial line, wherein the coaxial line is designed as a torsion sensor and for this purpose has an inner conductor and an outer conductor, wherein between the outer conductor and the inner conductor, a gap is formed, in which a dielectric is arranged, wherein the inner conductor and the outer conductor are spaced apart at a distance, resulting in an impedance due to the distance and the dielectric, wherein the outer conductor is deformable, so that a torsion leads to a deformation of the outer conductor and thus to a change in the distance and a change in impedance, wherein an impedance is measured between the inner conductor and the outer conductor and wherein a torsion of the coaxial line is detected, if the impedance changes. Advantageous embodiments, developments and variants are the subject of the dependent claims. The statements regarding the coaxial line apply mutatis mutandis to the measuring arrangement and for the process and vice versa.

The coaxial line is designed as a torsion sensor, ie the coaxial line itself is designed as a sensor and not just a signal line for a separate sensor. The coaxial line is therefore also called a torsion sensor. The coaxial line is briefly referred to simply as a line. Due to the elongated configuration, the coaxial line is then suitable in particular for torsion measurement along the coaxial line, that is, not just for pointwise measurement of a torsion. By means of the coaxial line a torsion can be measured. In this case, the torsion of the coaxial line itself is measured, ie its own torsion or own torsion. In the intended According to the use of the coaxial line itself is thus twisted, ie twisted and subject to torsion, which is then measured by means of the line.

For torsion measurement, the coaxial line has an inner conductor and an outer conductor. The inner conductor and the outer conductor are generally referred to only as borrowed conductor. In particular, the conductors consist entirely of an electrically conductive material, for example aluminum or copper. The inner conductor is designed, for example, as a solid individual wire or alternatively as a stranded conductor. The inner conductor has in particular a conductor cross section in the range of 0.3 mm ² to 1 mm ² . The outer conductor is in particular circular. The outer conductor surrounds the inner conductor in particular fully. The inner conductor and the outer conductor are arranged concentrically, that is to say the outer conductor encloses an inner space which has a center in which the inner conductor is arranged. The coaxial line preferably also serves as a data line, ie as a line for data transmission, in particular for high-speed data transmission at frequencies above 10 GHz. For data transmission, a signal is applied to the inner conductor. The outer conductor then serves in particular as neutral. Between the outer conductor and the inner conductor, a gap is formed, in which a dielectric is arranged. The dielectric supports the outer conductor in particular. In this case, the dielectric is applied both to the inner conductor and to the outer conductor. The dielectric does not necessarily fill the interstice completely. The dielectric spaces the outer conductor from the inner conductor, so that the inner conductor and the outer conductor are spaced apart by a certain distance. In particular, in a ground state, ie, in a torsion-free state, the distance from the inner conductor along the entire coaxial line is constant. Due to the distance and the dielectric results in a certain impedance, which is measured as impedance between the inner conductor and the outer conductor.

It is essential that the outer conductor is deformable. In a torsion of the coaxial line then the outer conductor is deformed and thereby its distance from the Inner conductor changed. The outer conductor is thus designed such that it deforms during a torsion of the coaxial line and the distance to the inner conductor is changed. The changed distance also changes the impedance. This change is measurable and is advantageously measured in order to subsequently determine the torsion of the coaxial line. In this way, a torsion of, for example, 90 ° to 10 cm in length is advantageously measurable.

A core idea of the invention thus consists, in particular, of intentionally allowing a deformation of the outer conductor and in this way promoting a change in impedance for the purpose of torsion measurement. This is in contrast to conventional coaxial cables, in which the outer conductor or the unit of outer conductor and dielectric should be relatively stiff in order to maintain a fixed distance as possible between the outer conductor and the inner conductor even under mechanical stress. Of corresponding importance is the interaction of the outer conductor with the dielectric, which advantageously supports the outer conductor and thus keeps it in the unloaded state, but permits deformation of the outer conductor in the event of a torsional load. Preferably, the dielectric is correspondingly deformable, so that it also gives way in the event of a torsional load. A torsion of the coaxial line thus leads overall to a change in geometry, particularly in cross-section with respect to the longitudinal direction. However, the inner conductor is preferably not deformable.

Preferably, the outer conductor is formed as a braid. The outer conductor is thus a braid shield. The braid is composed in particular of a plurality of individual elements, in particular individual wires. In addition, the braid preferably has a braid angle which is at least 25 °, preferably at least 45 °. The braid angle indicates in which angle with respect to the longitudinal axis, the individual elements are employed. By the

Braid angle results in an overall helical or helical course of the individual elements around the inner conductor and the dielectric around. A larger braid angle thus leads to the same length to more revolutions of a single element around the inner conductor. Typically, smaller braid angles than those given above are used to make the outer conductor particularly stable form. In the present case, however, a high deformability is explicitly desired, which is why a particularly large braid angle of at least 25 °, preferably at least 45 °, is chosen. At such a high

Braid angle leads a torsion of the coaxial line to a particularly strong deformation, in particular compression and thus a correspondingly well measurable impedance change. Basically, the braid angle is not limited to the top, but preferably the braid angle is at most 80 °.

In an expedient embodiment, the outer conductor is designed as a braid, preferably as described above, and additionally a number of reinforcing elements are incorporated into the outer conductor, in particular braided, so that the outer conductor can be reversibly deformed. This makes it possible in a particularly simple way a recurrent measurement of the torsion, because the outer conductor automatically resumes the shape of the ground state as soon as the torsional load subsides. The reinforcing elements advantageously prevent buckling, i. an irreversible deformation of the individual elements.

In addition, the reinforcing elements advantageously have a supporting effect, which keeps the outer conductor in the unloaded state in shape. The reinforcing elements thus act as support elements. Particularly preferred are reinforcing elements, which have the lowest possible elongation, ie are not stretchable. By this is meant that the reinforcing elements have an elongation of less than 1%, preferably less than 0.1%. Due to the lack of extensibility of the reinforcing elements, the deformation of the outer conductor is also advantageously supported in such a way that, in the event of torsion, the reinforcing elements and thus the entire outer conductor deflect in the radial direction and, in particular, inwardly and are not merely pulled apart. The reinforcing elements are formed, for example, as fibers, wires or filaments, and generally preferred as elongate filaments, each extending in particular along the entire coaxial line. A respective reinforcing element then replaces, for example, one of the individual elements of the braid. Alternatively or additionally, the reinforcing elements are additionally incorporated in the braid. Expediently, the reinforcing elements run in the same braid angle as the individual elements. Particularly suitable are reinforcing elements, which are formed as fibers and consist of aramid. Aramid has a particularly high tensile strength and is characterized by a particularly low elongation.

Preferably, the dielectric is reversibly deformable and in particular reversibly compressible. The dielectric is preferably elastic. When the torsion subsides, the dielectric thus advantageously returns to a basic shape and advantageously restores a basic shape of the outer conductor due to the supporting action. By using a reversibly deformable dielectric, a torsion can then be measured in a simple manner repeatedly or repeatedly in the same way. With regard to the reversible deformability, the statements in connection with the reversibly deformable outer conductor also apply analogously to the dielectric and vice versa.

A particularly suitable material for the dielectric is a thermoplastic rubber, referred to as TPV for short. Alternatively, polyurethane, short PUR is particularly suitable.

Alternatively or additionally, the dielectric is irreversibly deformable. This can be combined with the abovementioned reversibly deformable embodiment insofar as, in a suitable variant, the dielectric is then partially reversible and, for example, longitudinally reversible and irreversibly deformable. On a first section, the dielectric is then reversibly deformable and irreversibly deformable on a second section. Even a partial provision is conceivable and suitable. An irreversible deformation is understood to mean a deformation which is permanent and thus remains when the torsion ceases. As a result, a torsion can advantageously also be retrofitted and fixed in an undated condition. A particularly suitable material for the dielectric, especially in this context, is polyethylene, PE for short. In a particularly preferred embodiment, the dielectric is formed as a profile part. A profile part is characterized in particular by the fact that viewed in the longitudinal direction has an unchanged cross-section, ie at each longitudinal position has the same cross-section. The profile part has a center, in which the inner conductor is arranged and which surrounds the inner conductor in particular in full circumference. The profile part has an outer area, which is arranged around the center. In the outdoor area a number of cavities is introduced. The term "a number of" also includes a configuration with only a single cavity. The cavities are in particular empty, ie empty cavities, ie no further materials or line components are arranged in the cavities. The cavities serve in particular as evasion volumes for the dielectric during a deformation. The cavities are also referred to as chambers. The cavities preferably have macroscopic dimensions, ie in particular in each case a diameter of at least 1 mm, preferably of at least 5 mm. Due to the cavities, the dielectric preferably fills the gap at least 10% and at most 50%. The profile part is either solid or made of a foamed material. As a foamed material, in particular decalcified polyurethane is suitable.

The configuration with cavities is also advantageously suitable for detecting a media intrusion. In the event of a break in a medium, e.g. Water, this penetrates into the cavities leads there to an altered relative permittivity. This in turn leads to a change in the impedance, which can be measured accordingly and preferably also measured for this purpose. In such an embodiment, the coaxial line is designed in addition to the configuration as a torsion sensor as a media sensor.

In a particularly expedient embodiment, the dielectric is formed as a profile part, which is a cross profile. The above statements to the profile part apply mutatis mutandis to the special cross profile. The profile part thus has a center, which surrounds the inner conductor, and an outer area, which now has a plurality of wings. The wings extend from the center to the outside and in the direction of the outer conductor, ie in particular in the radial direction. The wings preferably extend as far as the outer conductor and thus develop an advantageous supporting effect. Preferably, the wings are tapered towards the outside and for this purpose in particular triangular in cross-section. Preferably, three to 10 wings are formed, with particular preference 4 wings are formed. The wings are in particular of the same design. In particular, the wings are arranged distributed symmetrically around the center, so that the wings divide the gap in the circumferential direction into a corresponding number of equally sized sectors. The wings are either formed continuously, so that the individual sectors are not connected to each other, but separated. Alternatively, the wings are interrupted in sections or have through holes, so that the sectors are interconnected and, for example, a medium which enters one of the sectors can also enter the other sectors.

Alternatively or additionally, the dielectric completely fills the interspace. The dielectric is in this case designed in particular as a full part. To this extent, this can be combined with the abovementioned embodiment as a profile part, such that in a suitable variant the dielectric is then configured in sections, for example along the longitudinal section, as a profile part and as a full part. On a first section, the dielectric is then formed as a profile part and on a second section as a full part. For complete filling of the gap, the dielectric is in particular annular. In a suitable embodiment, the dielectric is made of a foamed material. The foamed material is in particular decalcified polyurethane. In contrast to a profile part with flea spaces as described above, a foamed material is understood as meaning a material which has a multiplicity of holes of comparatively small dimensions, ie in particular holes with a diameter of less than 1 mm, preferably less than 0.2 mm , In addition, with a foamed material, the holes are usually different large. A foamed dielectric has the advantage that such a material is particularly easily deformable. In principle, however, a solid part made from a deformable material is also conceivable and suitable. In an expedient refinement, the coaxial line has a measuring unit which is designed to measure the impedance between the inner conductor and the outer conductor. The measuring unit is also referred to as measuring electronics in particular. The measuring unit is thus integrated in the coaxial line, so that it is accordingly an intelligent coaxial line, which is designed to measure its own torsion and preferably to output. For this purpose, the measuring unit is suitably designed such that it initially measures the impedance between the two conductors, in particular recurring and preferably continuously, and then derives the torsion from the impedance. Alternatively, the measured impedance is simply output.

The concepts described above for the coaxial line are particularly suitable both for measuring the strength of the torsion and for measuring the position of the torsion. The strength is expediently determined directly by the detection of the change in the magnitude of the impedance. The position results from a merely local torsion as a corresponding only local impedance change. A position measurement takes place in a suitable embodiment by means of time domain reflectometry, TDR for short (ie time domain reflectometry) or by means of a vectorial network analyzer, VNA for short. However, particularly preferred is a measuring method as described in WO 2017/216061 A1, in particular there also S.2 Z.19 to S.3 Z.28. In this measuring method, measuring pulses are fed into the line at a specific clock rate. The measuring pulses are reflected and then propagate in the opposite direction, so that at certain points a superimposition of opposing measuring pulses results. This superimposition depends on the impedance of the coaxial line and is then determined to measure the same impedance. A torsion of the coaxial line as a whole results in an impedance change which leads to a transit time difference and accordingly changes the superimposition of the measuring pulses at a fixed, ie predetermined, measuring point. A mere local twist leads to a local one Impedance change, at which the measuring pulses are reflected, so that there is also a time difference, which influences the superposition at a fixed measuring point. Preferably, the measuring unit is designed to carry out this measuring method.

Alternatively, a measuring method is used, as described in the applicant's international application of 30.10.2017, file number PCT / EP 2017/077828, which is still unpublished at the time of application. Their disclosure content, in particular their claims (with accompanying explanations), are hereby expressly included in the present application. More specifically, reference is made to claims 1, 2, 6, 7 and 12 with the associated explanations, in particular on pages 5 / 6 and 8/9. In the course of a measuring cycle, a number of individual measurements are carried out, with one measuring pulse being fed in each individual measurement, whereby a stop signal is generated when a predetermined voltage threshold value (at the feed location) is exceeded due to the reflected signal component. measuring the measured signal and the stop signal is determined and the voltage threshold value between the individual measurements is changed. Therefore, exactly one stop signal is generated for each individual measurement. A further evaluation of the reflected signal does not take place. Due to the threshold value changed between the individual measurements, different impurities, which thus lead to different amplitudes in the reflection, are detected by the different propagation times, in particular also locally resolved.

Due to the large number of individual measurements, the transit times (stop signals) of the reflected components are therefore generally recorded at different defined threshold values. In this respect, this method can be regarded as a voltage-discrete time measurement method. The number of individual measurements is preferably more than 10, more preferably more than 20 or even more than 50 and, for example, up to 100 or even more individual measurements. From the large number of these individual measurements, therefore, a plurality of stop signals are determined which are distributed over time. are ordered. The plurality of stop signals in conjunction with the threshold values therefore approximately represent the actual signal course of the injected measurement signal and the reflected components. Conveniently, from these stop signals, the actual signal profile for a fed-in measuring signal reflected at the power end is approximated, for example, by a mathematical curve fit.

The aforementioned measuring arrangement has a coaxial line as described above and a measuring unit as described above. To connect to the measuring unit, the coaxial line in a suitable embodiment has a connection, e.g. a plug which is connected to the inner conductor and the outer conductor. When measuring, the coaxial cable is connected to the measuring unit by means of the connection. The measurement and evaluation thus advantageously take place predominantly outside the actual coaxial line. The above statements on the coaxial line with a measuring unit are analogously also applicable to the measuring arrangement with a coaxial line and a measuring unit, which is then arranged outside the coaxial line.

In a suitable variant, the measuring unit serves merely to supply a measuring signal, whereas an evaluation takes place separately from the measuring unit in an evaluation unit. The evaluation unit is a part of the measuring arrangement, but in particular arranged spatially separated from the coaxial line and the measuring unit. In one variant, the measuring unit is integrated in the evaluation unit or vice versa. The evaluation unit and the measuring unit are, for example, connected to one another via a wireless connection. The evaluation unit and the measuring unit are connected to each other, for example via the Internet. The evaluation unit is designed in a suitable variant as a central evaluation unit for monitoring a plurality of coaxial lines. Preferably, the evaluation unit is a server, which provides an evaluation of the sensor parameter as a cloud service. In particular, the object is also achieved by the use of a coaxial line as described above as a torsion sensor. In a particularly expedient development, the coaxial line is additionally used as a media sensor as described above. The coaxial line is used separately in a first variant, in a second variant, the coaxial line is integrated into an elongated connecting part. In general, the coaxial line is arranged in such a way that it extends between two mutually movable components and in particular connects them to one another. When used as intended, the coaxial line is twisted in particular, for example by the two connecting parts rotating relative to one another.

An embodiment of the invention will be explained in more detail with reference to a drawing. 1 schematically shows a coaxial line in a cross-sectional view, FIG.

Fig. 2 shows an outer conductor of the coaxial line of Fig. 1 in a side view.

In Fig. 1, a preferred embodiment of a coaxial line 2 is shown. This generally extends in a longitudinal direction L. The coaxial line 2 is at the same time designed as a torsion sensor. The coaxial line 2 has an inner conductor 4 and an outer conductor 6. In the present case, the outer conductor 6 is of circular design and surrounds the inner conductor 4 in its entirety. The inner conductor 4 and the outer conductor 6 are arranged concentrically in FIG. Between the outer conductor 6 and the inner conductor 4, a gap R is formed, in which a Dielekt- rikum 8 is arranged. The dielectric 8 supports the outer conductor 6 and abuts both the inner conductor 4 and the outer conductor 6. The dielectric 8 intends the outer conductor 6 from the inner conductor 4, so that a distance A is formed between them. The entire arrangement is surrounded by an unspecified outer sheath.

In Fig. 1, a ground state of the coaxial line 2 is shown, that is, the coaxial line 2 is in a torsion-free state. Due to the distance A and the dielectric kums 8 results in a certain impedance, which is measured to determine a torsion of the coaxial line 2. For this purpose, the outer conductor 6 is deformable, so that it deforms during a torsion and thereby the distance A to the Innenlei- ter 4 is changed. The changed distance A also changes the impedance which is measured in order to subsequently determine the torsion of the coaxial line 2.

In the exemplary embodiment shown, the outer conductor 6 is deformable in that it is formed as a braid. The outer conductor 6 is thus a braided shield. To illustrate the braid and its structure, the outer conductor 6 in FIG. 2 is shown in highly schematic form in a side view. The braid is composed of a plurality of individual elements 10, which are here individual wires. The braid has a braid angle G, which is measured as shown in Fig. 2 with respect to the longitudinal direction and is at least 25 °. Due to the presently large braid angle G, a particularly long circulation of a respective individual element 10 around the inner conductor 4 results over a certain length.

In addition to the individual elements 10, a plurality of reinforcing elements 12 are woven into the outer conductor 6, so that the outer conductor 6 is reversibly deformable. The reinforcing elements 12 also serve as supporting elements which secure the outer conductor 6 in the unloaded state, i. keep in shape in the ground state. The reinforcing elements 12 run in the same braid angle G as the individual elements 10. In the illustrated embodiment, reinforcing elements 12 are formed as fibers and consist of aramid, which has a particularly high tensile strength and is characterized by a particularly low elongation.

The dielectric 8 is made of polyurethane in the illustrated embodiment. In a non-fabricated variant, the dielectric 8 consists of a thermoplastic rubber. In these variants, the dielectric 8 is in particular reversibly deformable and returns to the ground state when the torsion subsides. In an alternative, not shown, the dielectric 8 consists of polyethylene and is general and irreversibly deformable. In further variants, the dielectric 8 consists of other materials.

In the exemplary embodiment shown, the dielectric 8 is designed as a profile part. This has a center 14, in which the inner conductor 4 is arranged and which surrounds the inner conductor 4 in particular in full circumference. The profile part further has an outer region, which is arranged annularly around the center 14 and in which a number of four cavities 18 are introduced here. In the present case, the cavities 18 are empty and serve, in particular, as an evasive volume for the dielectric 8 during a deformation. In the present case, the cavities 18 each have a diameter of at least 1 mm and make up the major part of the exterior area.

The cavities 18 are also suitable for detecting a media intrusion in which a medium, e.g. Water penetrates into the cavities 18 and there leads to an altered relative Perm ittivity. This in turn leads to a change in the impedance, which can be measured accordingly. The coaxial line 2 is thus additionally designed as a media sensor. As can be clearly seen from FIG. 1, the dielectric 8 in the embodiment shown is designed as a special one as a cross profile. The outer area has several, here four wings 20, which extend from the center 14 to the outside and in the direction of the outer conductor 6 and reach up to this. The wings 20 are tapered towards the outside and triangular in cross-section. The wings 20 are arranged distributed symmetrically around the center 14 and subdivide the gap R in the circumferential direction into a corresponding number, here four equally sized sectors, namely the cavities 18.

In a variant which is not shown, the dielectric 8 completely fills the gap R and is then formed as a full part. In addition, a measuring unit 22 is shown in FIG. The coaxial line 2 forms a measuring arrangement with the measuring unit 22. In a variant, the measuring unit 22 is integrated in the coaxial line 2. The measuring unit 22 is designed to measure the impedance between the inner conductor 4 and the outer conductor 6 and connected thereto in a manner not shown.

Claims

claims

1. coaxial line, which is designed as a torsion sensor and for this purpose has an inner conductor and an outer conductor,

wherein between the outer conductor and the inner conductor an intermediate space is formed, in which a dielectric is arranged,

wherein the inner conductor and the outer conductor are spaced apart at a distance,

wherein an impedance results due to the distance and the dielectric,

- Where the outer conductor is deformable, so that a torsion leads to a deformation of the outer conductor and thus to a change in the distance and a change in the impedance.

2. Coaxial cable according to claim 1, wherein the outer conductor is formed as a braid and wherein the braid has a braid angle which is at least 25 °, preferably at least 45 °.

3. Coaxial cable according to one of claims 1 to 2, wherein the outer conductor is formed as a braid and wherein in the outer conductor, a number of reinforcing elements is incorporated, so that the outer conductor is reversibly deformable.

4. Coaxial cable according to claim 3, wherein the reinforcing elements are formed as fibers and consist of aramid.

5. Coaxial cable according to one of claims 1 to 4, wherein the dielectric is reversibly deformable.

6. coaxial cable according to one of claims 1 to 5, wherein the dielectric is irreversibly deformable, so that a torsion is still subsequently and in not twisted state fastened.

7. Coaxial cable according to one of claims 1 to 6,

- wherein the dielectric is formed as a profile part,

- wherein the profile part has a center in which the inner conductor is arranged,

- Wherein the profile part has an outer area in which a number of cavities is introduced.

8. coaxial cable according to one of claims 1 to 7,

- wherein the dielectric is formed as a profile part, which is a cross profile,

- wherein the profile part has a center which surrounds the inner conductor,

- Wherein the profile part has an outer area, with a plurality of wings, which extend from the center to the outside and in the direction of the outer conductor.

9. Coaxial cable according to one of claims 1 to 8, wherein the dielectric completely fills the gap.

10. Coaxial cable according to one of claims 1 to 9, wherein it has a measuring unit, which is designed to measure the impedance between the inner conductor and the outer conductor.

11. measuring arrangement which has a coaxial line and a measuring unit,

wherein the coaxial line is designed as a torsion sensor and for this purpose has an inner conductor and an outer conductor,

wherein an impedance results due to the distance and the dielectric,

wherein the outer conductor is deformable, so that a torsion leads to a deformation of the outer conductor and thus to a change in the distance and to a change in the impedance,

- wherein the measuring unit is designed to measure the impedance of the line,

- The cable has a connection, for connection to the measuring unit.

12. Method for measuring a torsion of a coaxial line,

wherein an impedance results due to the distance and the dielectric,

- Wherein an impedance is measured between the inner conductor and the outer conductor and wherein a torsion of the coaxial line is detected, if the impedance changes.