sliding cable

Abstract

The invention relates to a sliding cable (1) for guiding a sensor unit, in particular an image acquisition unit, through elongated cavities such as channels or pipes, with a flexible, rigid, concentrically longitudinally extended inner body (3) made of insulating material, in the radially outer region of which several longitudinally extending electrical conductors (5) spaced apart in the circumferential direction are embedded. Advantages for manufacture and use are obtained by the fact that, for transmitting sensor signals, in particular image signals, an inner conductor (4) made of stranded conductors is embedded coaxially and centrally in the inner body (3).

Description

[0001] The invention relates to a sliding cable for guiding a sensor unit, in particular an image acquisition unit, through elongated cavities, such as channels or pipes, with a flexible, rigid, concentrically longitudinally extended inner body made of insulating material, in the radially outer region of which several longitudinally extending electrical conductors spaced apart in the direction of circulation are embedded.

[0002] A sliding cable of this type is disclosed as known in DE 10 2015 202 708 A1. In this known sliding cable, particularly in the form of a data cable, a longitudinally extending structural element is provided for stiffening, into which a number of conductors are embedded spaced apart in the circumferential direction in a radially outer region. The conductors and the structural element are surrounded by a common shield made of a conductive material.

[0003] Such a sliding cable is also shown in US 2014 / 0 147 086 A1, where conductors are embedded on the outside in an inner body.

[0004] Another push cable is described in DE 10 2016 120 717 B4. In this push cable, a conductor arrangement for transmitting digital signals is positioned centrally along a longitudinal axis and enclosed by a sheath-like casing made of a fabric with flexible reinforcing bars. An outer protective sheath surrounds the fabric. The coaxial conductor arrangement consists, for example, of a central inner conductor, a coaxial dielectric surrounding it as insulation, and a coaxial outer conductor. The reinforcing bars give the push cable the necessary rigidity to allow, for example, a camera as an image acquisition unit to be pushed through narrow, curved cavities such as sewer pipes. After passing through a bend, the rigid cable can return to its straightened original position due to its flexible properties.

[0005] The applicant is also aware of sliding cables which comprise an inner body made of flexible, rigid material extending axially along its length in the center and electrical conductors made of solid material or in the form of stranded conductors embedded in its radially outer area and extending along the length of the sliding cable, in order to transmit control signals and / or sensor signals to a sensor system arranged on the front of the sliding cable, in particular an image acquisition unit, and also to supply the required electrical energy.

[0006] Examples of the use of push cables in conjunction with, for example, an image acquisition device for carrying out measurements in channels are shown in DE 10 2008 003 593 A1 and DE 299 08 073 U1.

[0007] The present invention is based on the objective of providing a sliding cable of the type mentioned above, which can be manufactured with as little effort as possible and achieves the best possible transmission properties.

[0008] This problem is solved in a sliding cable with the features of claim 1. According to the invention, it is provided that, for the transmission of sensor signals, in particular image signals, an inner conductor made of conductor strands is embedded coaxially in the inner body.

[0009] With this design, sensor signals, especially image signals, can be transmitted with high transmission quality via the central inner conductor and the sliding cable to a connected processing unit. The electrical conductors arranged in the radially outer region can be used as relatively simple control lines for bidirectional and / or unidirectional control of relevant actuators or additional sensors. This eliminates the need for a complex design consisting of individual stranded conductors with correspondingly high-frequency transmission characteristics. Advantageously, more than two or more than three individual conductors can be used as electrical conductors arranged in the radially outer region of the inner body.

[0010] One advantageous design for the construction and use consists in the electrical conductors being arranged equidistantly to each other in the direction of circulation and radially to the center of the cable.

[0011] A further advantageous design for the structure is achieved by making the electrical conductors from solid material and identical to each other.

[0012] The construction of the inner body from basalt material or carbon fiber material also contributes to advantageous function and good usability due to its flexible, rigid properties for guiding a connected sensor unit and, if applicable, actuators.

[0013] Advantages for its use arise particularly from the fact that the inner conductor is designed for the transmission of high-resolution image data.

[0014] The invention is explained in more detail below with reference to exemplary embodiments and the drawing. It shows: Fig. 1 a cross-section of a sliding cable in schematic representation.

[0015] A in Fig.A sliding cable 1, shown in cross-section, has a central coaxial inner conductor 4 extending along its length, consisting of a plurality of thin strands. The inner conductor 4 is surrounded by an inner body 3 made of insulating material, in particular basalt or carbon fiber, and is designed to be flexible with the required bending stiffness so that the sliding cable 1 automatically returns to its straight alignment when bending forces acting after a bending operation subside. The insulating, flexible inner body 3 also extends along the length of the sliding cable 1.

[0016] In the radially outer region of the inner body 3, several, in this case six, electrical conductors 5 are embedded, preferably more than two or three electrical conductors 5, which are arranged equidistant from each other in the circumferential direction and preferably also have the same radial distance to the center M. The electrical conductors 5 lie outside an imaginary central circle with mean radius of the annular inner body 3, in particular near the outer circumference of the inner body 3, but are covered towards the outer circumference of the inner body 3 by the insulating material of the inner body 3 and are thus completely embedded in the inner body 3. In a preferred embodiment, the electrical conductors 5 consist of solid material, in particular copper or a similarly highly electrically conductive metal material. The electrical conductors 5 also extend over the entire length of the sliding cable 1.

[0017] To protect the inner body 3 with the electrical conductors 5 embedded in it and the inner conductor 4, the sliding cable 1 is surrounded on the outside by an outer sheath 2 made of resistant plastic material.

[0018] The sliding cable 1, for example, has an outer diameter of at most 8 mm or 10 mm. The diameter of the insulating inner body 3 is, for example, at most 7.5 mm or at most 6 mm. The electrical conductors 5, which are made of solid material, have, for example, a diameter of at most 1 mm, e.g., at most 0.6 mm. The inner conductor 4, located in the center of the coaxially constructed cable and consisting of a multitude of individual strands, has, for example, an outer diameter of at most 4 mm or at most 3 mm, e.g., 2.5 mm.

[0019] The inner conductor 4 can be used to transmit high-resolution image signals, as it is designed for transmitting correspondingly high frequencies and offers a high bandwidth in combination with the other components of the sliding cable 1. The electrical conductors 5 can be advantageously used to transmit electrical energy to sensors and / or actuators connected to the front of the sliding cable 1, as well as for transmitting control signals.

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