Two-conductor system for earth-boring drilling rod lengths

Abstract

The invention relates to a two-conductor system for earth drill rod sections for forming a drill string for an earth drilling device, wherein the two-conductor system comprises an insulated assembly of a first conductor and a second conductor, and the first and second conductors are each exposed at one end of the assembly in a connection direction, and at least one section of an exposed end of one of the conductors is circumferentially surrounded by an inner and an outer insulating sleeve.

Description

[0001] The invention relates to a two-conductor system for earth drill rod sections for forming a drill string for an earth drilling device, an earth drill rod section with a two-conductor system, and an earth drill rod section system with a two-conductor system for earth drill rod sections for forming a drill string for an earth drilling device.

[0002] In drill-rod-based drilling in the ground using an earth drilling rig, particularly for creating so-called horizontal boreholes, a drill head is typically driven by a drive unit located at the earth's surface or in an excavation pit via a drill string. The drill strings used can consist of individual, interconnected sections of drill rod, which—following the drilling path—are successively attached to and connected with the rear end of the already drilled section.

[0003] To supply electrical equipment and / or transmit signals within the drill string, it may be necessary to provide electrical connections between the individual drill string sections. For this purpose, it is known to use a conductor or cable that can be routed inside the drill string section.

[0004] A disadvantage of the otherwise well-functioning conductors in the earth drill rod sections can arise from a possible short circuit, especially if drilling fluid is used during drilling or creating the earth borehole and more than one conductor is provided in the earth drill rod section.

[0005] DE 1 178 384 B discloses a hollow pump rod with internally arranged electrical conductors, wherein the cable string carrying the electrical conductors preferably has cylindrical expansions with larger cross-sections in the region of its ends, which are arranged concentrically inside the hollow pump rod and are positively connected to the rod itself by the expansions of the cable string. The cable string has a tubular outer conductor and a rod-shaped inner conductor. The two current-carrying conductors are in turn protected from each other and from the hollow pump rod by outer and inner insulation. A contact plug, which is inserted into the expanded end section of the cable string between the outer conductor and the rod-shaped conductor, serves to provide the electrical connection between the respective adjoining hollow pump rods.

[0006] EP 0 860 907 A2 discloses a multi-conductor system with insulation. It includes a first conductor (286, 284) and a second conductor (286, 284), each exposed at one end of the assembly in a connection direction. A connecting body made of an electrically non-conductive material and individual insulation for each conductor are provided.

[0007] Based on this prior art, the invention was based on the objective of creating a two-conductor system for earth drill rod sections for forming a drill string for an earth drilling device, an earth drill rod section with a two-conductor system, and an earth drill rod section system with a two-conductor system for earth drill rod sections for forming a drill string for an earth drilling device, with which it is possible to form and disconnect the connection of the earth drill rod sections as easily as possible, in particular without the occurrence of a short circuit.

[0008] The problem is solved by the subject matter of the dependent claims. Advantageous further developments of the subject matter of the dependent claims are the subject matter of the respective dependent claims and are described below.

[0009] The term "two-conductor system" as used in the invention describes a system that can be arranged in a section of the auger string, which itself is designed to form a drill string for an auger. The two-conductor system can have a length adapted to the auger string in which it is to be arranged. The two-conductor system can be fixed at each end within the auger string. This fixing can be achieved essentially in the center of the auger string. Preferably, the fixing at the end of the two-conductor system within the auger string can be accomplished using centering stars.

[0010] The two-wire system described here can be used to upgrade an existing earth drill string, allowing the integration of a two-wire system within the drill string. This system enables the use of multiple conductors (at least two) for transmitting power and / or signals over at least a section of the drill string. The two-wire system offers added value to the user of a drill string-based earth drilling rig, for example, by allowing the supply of power and / or signals to units located near the drill head. In particular, the availability of more than one conductor offers significant advantages, as the two conductors can be used independently and are not limited in their application for future tasks or for units located near the drill head.

[0011] The term "conductor" as used in this description refers to an electrically conductive conductor. The term "two-conductor" as used in this description refers to a system containing at least two conductors. It may also be specified that the two-conductor system contains exactly two conductors.

[0012] The term "drill rod section" as used in this description encompasses individual, particularly rigid, drill rod sections that can be directly or indirectly connected to one another to form a drill string or drill string in the longitudinal axial direction. The drill rod sections can be connected by inserting or screwing them together with or without an intermediate element. Combinations of inserting and screwing the drill rod sections together are also possible. The connection of the drill rod sections can be achieved, in particular, by screwing or inserting one end of one drill rod section to the other end of another drill rod section.

[0013] The term "drill string" as used in this description comprises several interconnected sections of the drill string. The drill string can extend longitudinally along the longitudinal axis of the drill string sections in a drill string axis that is essentially congruent with or coincides with the longitudinal axes of the drill string sections. The drill string can have a drill head at one end, particularly at the front, and optionally a drill head tip, which may be designed as a drilling tool (for example, as a reaming head), or a section adjacent to the drill head, which may have the same orientation as the drill head. The drill string can have a sensor section or a sensor housing in the area of ​​the drill head or in a section adjacent to the drill head, in which one or more sensors may be arranged.

[0014] The term "earth drilling device" encompasses, for the purposes of this description, any device capable of moving a drill string, particularly one comprising sections of the drill rod, within an existing or newly created channel in the ground, in order to create or enlarge a borehole, especially a horizontal borehole (HD), or to install pipelines or other long objects in the ground. The earth drilling device may, in particular, be an HD device. An earth drilling device can be a device that drives a drill string and, in particular, can displace soil. The drill string can be inserted into the ground translationally and / or rotationally in its longitudinal direction. The drill string can be moved within the ground by the earth drilling device through tension or compression.

[0015] The term "soil" as used in this description encompasses any type of material, in particular earth, sand, rock, stone, and / or stone, in which existing or to be created, preferably at least partially horizontal, channels or boreholes can be installed. An underground arrangement of the soil is preferred, but not mandatory.

[0016] For the purposes of this description, the term "insulated assembly" encompasses a first conductor and a second conductor that can be handled together. The first and second conductors can be handled together as a single element or as a single piece. The term "insulated" indicates that the two conductors are connected in such a way that they are insulated from the outside. The first and second conductors are surrounded by insulation that is arranged circumferentially around the first and / or the second conductor.

[0017] The term "connection direction" encompasses, in the sense of the description, a direction that expresses that a connection exists in the longitudinal axial direction of the two-conductor system, which leads away from the two-conductor system or the first and / or second conductor in the longitudinal axial direction of the two-conductor system.

[0018] If the two-wire system is arranged in the earth drill string section, the connection direction points outwards from the end(s) of the earth drill string section.

[0019] One of the conductors can be circumferentially surrounded, at least partially, by both the inner and the outer insulating sleeve. In one section, both the inner and the outer insulating sleeve can surround the single conductor. It can be provided that one of the insulating sleeves, in particular the outer insulating sleeve, projects beyond the other insulating sleeve, in particular the inner insulating sleeve. This projection in the longitudinal axial direction can extend away from the two-conductor system and / or towards the two-conductor system. It can be provided that one of the two insulating sleeves, in particular the outer insulating sleeve, grips the other insulating sleeve, in particular the inner insulating sleeve, especially in a clamping manner, with respect to the longitudinal axis of the insulating sleeve(s) or the two-conductor system.One of the insulating sleeves, in particular the outer insulating sleeve, may have a length that is at least 1.5 times, and in particular at least 2 times, longer than the other insulating sleeve.

[0020] The invention follows the core idea of ​​providing a configuration in which at least one section of an electrical conduction path is designed differently from the prior art. A section extending towards the two-conductor system is provided, connecting to the exposed end of one of the conductors. This departs from the previous consideration that the conduction path, starting from the exposed end of one conductor, must be formed in a substantially straight, forward-directed manner, essentially away from the conductor. It was recognized that, in order to reduce short circuits between the conductors, an electrical conduction path can be provided which has at least one section extending from an exposed end of one conductor of the two-conductor system in a direction away from the adjacent end of the two-conductor system and back towards the two-conductor system.The electrical conduction path, by means of which the exposed end of one conductor can be directly or indirectly connected to a conductor of another two-conductor system, has a section that lies between the exposed end of the first conductor and a conductor of the second two-conductor system. This section leads away from the exposed end and the end of the two-conductor system adjacent to the exposed end, in the opposite direction when viewed along the longitudinal axis. The electrical conduction path may have a "backward" portion, which includes a section that is routed back via a segment of the conductor whose exposed end is in electrical contact with the electrical conduction path.By designing the electrical conductor path, which extends from the exposed end (and the end of the two-conductor system adjacent to the exposed end) towards a central region along the longitudinal extent of the two-conductor system, sections of the conductor path of one conductor can be arranged radially "one above the other." Two of these "one above the other," or essentially parallel, sections of the single conductor, or its electrical conductor path, can be spaced apart from each other by means of insulation (which can also be the insulation of the entire assembly). This allows the two conductors in the earth drill string to be separated from each other in such a way that, in particular, a short circuit is largely prevented. The prevention of short circuits between the two conductors can be effectively and largely prevented.

[0021] The invention provides a two-conductor system for earth drill strings for forming a drill string for an earth drilling device, in which the two-conductor system comprises an insulated assembly of a first conductor and a second conductor. The first and second conductors are each exposed at one end of the assembly in a connection direction. An electrical conduction path is formed for at least one of the conductors, extending from the exposed end of one conductor across the insulation of that conductor and / or the assembly in the opposite direction to the connection direction, and from there passing in the connection direction, insulated, past the end of one conductor. This effectively addresses the second aspect of the invention, namely the prevention of short circuits.

[0022] The term "exposed" in this description encompasses the configuration in which access to the conductor is possible, particularly in a radial direction or at its circumference. The term "exposed" thus includes the configuration in which no insulation is present on the circumference of the exposed area or end of the conductor.

[0023] The term "electrical conduction path" refers to a conductive section or path along which a current or signal can be carried. The electrical conduction path of the at least one conductor, or the electrical conduction path extending from the exposed end of the at least one conductor, can be configured such that a section of the path is separated from the conductor by insulation of the conductor and / or the composite material. This section, relative to the conductor's radial direction, is located "next to," "above," or "below" the conductor. With respect to the direction of connection, a section of the electrical conduction path is formed that runs counter to the direction of connection.

[0024] The design of the described "electrical conduction path" aims to create a "longer" conduction path than previously possible in the prior art. This "longer" electrical conduction path of the single conductor can improve short-circuit performance, particularly when using drilling fluid or a drilling fluid that is guided through the drill string.

[0025] In a preferred embodiment, the assembly comprises a coaxial cable, and the two conductors are the inner and outer conductors of the coaxial cable. This allows for a particularly simple design of one component of the two-conductor system. Coaxial cables are easy to handle and use.

[0026] In a preferred embodiment, the exposed end of one conductor is contacted by means of an electrically conductive ring located at the exposed end. This ring seals the insulation of the conductor and / or the assembly by pressing an insulating sealing element onto the insulation of the conductor and / or the assembly. This design allows for both a simple contact method and the largely ensured integrity of the assembly and / or the conductor's insulation. The ring can be used not only to provide part of the electrical conduction path but also to maintain the integrity of the insulated assembly even in the presence of pressurized drilling fluid.Without a seal, the pressurized drilling fluid could, in the area of ​​the exposed end of the conductor, penetrate under the insulation of the individual conductor or the assembly, potentially causing the insulation to detach over time. A synergistic effect can be achieved by using an electrically conductive ring, which can both ensure the electrical conductivity of the conductor path and maintain the integrity of the insulation of the individual conductor or the assembly.

[0027] In a preferred embodiment, the ring can be screwed onto or into a counterpart that surrounds the insulation of one conductor and / or the composite, resting against the outer surface of the composite. The insulating sealing element, together with the ring, can be pressed onto the insulation of one conductor and / or the composite by means of an axial directional component during screwing. This allows for a simple, easy-to-design, and easy-to-plan connection that may only require screwing the ring and the counterpart together.

[0028] In a preferred embodiment, a front section of the ring is surrounded by an insulating sleeve, in particular the outer insulating sleeve, in the connection direction. It can be achieved that an insulating sleeve, especially the outer insulating sleeve, shields the ring in a direction corresponding to the connection direction and commonly referred to as "forward" (away from the two-conductor system) in order to create a "distance" between the conductors or the formed electrical conduction path of one conductor to the other conductor or its exposed end. The insulating sleeve can, as one of possibly several elements, support the effect or formation of the "backward" electrical conduction path.

[0029] In a preferred embodiment, an electrically conductive connecting sleeve surrounds an insulating sleeve, in particular at least partially the outer insulating sleeve, and extends at least partially over the ring and / or the mating part. A section of the electrical conductor path, designed in the direction of connection, can be created by means of the electrically conductive connecting sleeve, which leads to the rear / backward region (into the central region of the two-conductor system), where the electrical conductor path initially extends from the exposed end of one conductor. The electrical conductor path, which initially extends backward from the exposed end, i.e., against the direction of connection, can be guided forward again, i.e., in the direction of connection, by means of the connecting sleeve. The electrically conductive connecting sleeve provides an easy-to-handle, easy-to-construct, and easy-to-use element.Alternatively, a simple plug connection can be used. The connecting sleeve can be slid over the ring and / or the ring's counterpart.

[0030] In a preferred embodiment, the two-wire system for earth drill string sections, used to form a drill string for an earth drilling device, includes a pressure relief valve for releasing excess pressure from the two-wire system. This makes it possible to maintain the pressure within the two-wire system at or substantially equal to, or slightly higher than, the pressure level outside the two-wire system. Advantageously, this largely prevents excessive overpressure within the two-wire system. Excessive overpressure could, for example, cause fluid from the two-wire system to reach the electrical first or second conductor(s), potentially leading to a short circuit.

[0031] Providing a pressure relief valve initially seems counterintuitive without the insights gained from the invention, since a pressure relief valve inherently requires an opening through which excess pressure can be released. However, such an opening is generally undesirable for those skilled in the art, as it can pose a risk of liquid or contaminant entering the two-pipe system. The merit of the invention lies in its recognition that a directed opening can indeed offer an advantage.

[0032] The term "pressure relief valve" refers to any valve that can open when the pressure in the two-pipe system rises above a set pressure. This set pressure is essentially the pressure above the ambient pressure outside the drill string. It is understood that, due to the sealing effect required by the pressure relief valve, which creates a restoring or pre-tensioned seal between the closure or shut-off element and the sealing surface or valve seat, the pressure at which the pressure relief valve opens may be slightly higher than the ambient pressure.

[0033] The term "area of ​​the two-wire system" refers to an area intended for connecting a first and / or a second electrical conductor of the two-wire system with a corresponding first and / or second electrical conductor of the two-wire system.

[0034] A preferred embodiment relates to creating insulation for a two-conductor system that provides improved insulation between the multiple conductors, while maintaining the ease of handling the drill string sections, particularly during assembly and disconnection. This approach, which initially appears contradictory, involves providing not just one insulating sleeve around one of the conductors, but two insulating sleeves around the same conductor, which have different longitudinal extensions along the length of one or the two conductors. In the preferred embodiment, at least one section of an exposed end of one of the conductors is circumferentially surrounded by an inner and an outer insulating sleeve. This provides effective insulation for the single conductor.

[0035] The invention also provides an earth drill section with a two-conductor system. The two-conductor system is arranged, in particular by means of at least one centering star, substantially centrally within a cavity extending along the longitudinal axis of the earth drill section. The earth drill sections can be pre-assembled with the described two-conductor system. The arrangement using at least one centering star, with a centering star potentially being provided at each end of the earth drill section, also allows for easy maintenance and / or simple replacement in case of wear.

[0036] The invention also provides an earth drill rod system with several earth drill rod sections having a two-conductor system, wherein the earth drill rod sections can be connected to each other to form a section of a drill string.

[0037] At least one, or preferably all, sections of the auger system can be fitted with at least one or more pressure relief valves at at least one end, preferably exactly one end. The pressure relief valve(s) can be designed and arranged to prevent overpressure relative to the ambient pressure of the drill string within the cavity of the auger section or in the area of ​​the two-pipe system. At least one pressure relief valve at one end of the auger section can be sufficient to release overpressure when two auger sections are connected. In particular, it can release overpressure that may occur when two auger sections are connected.

[0038] The pressure relief valve can be designed as one or more closable openings in a section of the earth drill string, connecting the cavity containing the two-pipe system to the surrounding environment. These openings can extend as closable through-holes from the area of ​​the two-pipe system or the cavity to the outside.

[0039] An earth drill string section can have at least one channel in its wall to form a pressure relief valve; this channel can have any configuration with regard to its direction and cross-sectional shape. Multiple channels can also be provided to form a pressure relief valve.

[0040] A straight channel design can be advantageous for ease of manufacture. A straight design perpendicular to the longitudinal axis of the auger rod section may be preferred to allow for the shortest possible channel design, simplify manufacturing, and / or minimize the weakening of the auger rod section's integrity. A curved and / or straight channel design at any angle to the longitudinal axis of the auger rod section is not excluded.

[0041] A round, especially circular, cross-sectional shape for the channel can simplify manufacturing, as the channel can, for example, be produced as a bore. Other designs are not excluded; in particular, a cross-sectional shape that is at least partially straight is possible.

[0042] The opening or channel may be designed to have a (closing) closure that acts in one direction against any overpressure in the cavity or the area of ​​the two-pipe system. This closure may, for example, be in the form of a flap. For instance, the opening or channel may have an elastic or movable flap-shaped closure that can at least partially rest against the opening or channel wall and be pre-tensioned against it. If the pressure in the cavity or the area of ​​the two-pipe system increases, the closure can lift away from the opening or channel wall and, after a decrease in pressure, return to its position resting against the opening or channel wall.

[0043] It may be provided that one or more closable openings or channels open into a groove on the earth drill string section, with an O-ring being arranged in the groove to close the opening(s) or channel(s). It may also be provided that the openings or channels open into separate grooves, each of which may contain an O-ring. A groove with an O-ring can simplify manufacturing and design. In the event of overpressure, the O-ring can briefly (minimally) lift to relieve the overpressure and, once the pressure has subsided, return to resting in the groove on the opening, thus sealing it.

[0044] Alternatively or additionally, a pressure relief valve can be designed by providing one or more O-rings that circumferentially surround one section of the auger string and seal it against another section of the auger string (connected to the first). Such O-rings are known in the field of hydraulic cylinders and allow pressure to be released in one direction while providing a seal in the other. When the auger string sections are connected, any resulting pressure build-up can be released. If increased external pressure acts on the connection point with the O-ring(s), the O-ring(s) seals.

[0045] A simple end connection between the auger sections can be provided, which may be designed as a plug-in and / or screw connection. The ends of the auger sections and the ends of the two-wire system arranged within them can be aligned such that a positive connection of the two-wire system ends occurs when the ends of two auger sections are joined. For example, the auger sections can be screwed together, and during the screwing process, the two ends of the two-wire system can be connected via a plug-in connection.

[0046] The two-wire system is arranged, in particular by means of at least one centering star, essentially centrally within a cavity extending along the longitudinal axis of the auger section. The auger sections can be pre-assembled with the described two-wire system. The arrangement using at least one centering star, preferably one at each end of the auger section, also allows for easy maintenance and / or replacement in case of wear.

[0047] In a particularly preferred embodiment, an electrical conduction path, or a section thereof, particularly with respect to the electrical conduction path for one of the conductors described in the description and which has a "backward-directed" or "directional" section, can be formed via the connection between the two earth drill rod sections. Thus, a section of an electrical conduction path can be present via the connection between the earth drill rod sections. Since the outer casing of the earth drill rod section is made of an electrically conductive material, such a design is advantageous because it does not require any additional elements.

[0048] A section of an electrical conductor path for at least one of the conductors can lead to a centering star made of electrically conductive material, which is in electrically conductive contact with the housing of the earth drill string section. A section of the electrical conductor path for at least one of the conductors can be routed via the connection between the two earth drill string sections and led from the centering star of the other earth drill string section back into the conductor of the insulated assembly of the other earth drill string section.

[0049] Alternatively or additionally, it is possible to establish a direct connection between the centering stars, thus eliminating the need for a section of the electrical conductor path to pass through the housing of the drill string sections. A contact mechanism can be provided that electrically connects adjacent end centering stars when a connection is formed between drill string sections. For example, an electrically conductive element extending longitudinally along the drill string section can be provided on one of the centering stars, which, when the two drill string sections are connected, contacts the other centering star, which is also electrically conductive.

[0050] It is also described for use in transmitting electrical signals and / or electric current with a two-wire system for earth drill rod shots to form a drill string for an earth drilling device.

[0051] It is also described as being used to transmit electrical signals and / or electric current with a two-wire system for earth drill rod shots to form a drill string for an earth drilling device.

[0052] The ordinal numbers used in the description and claims do not represent any preference, ranking, or order; rather, the ordinal numbers are used to identify or distinguish the elements designated with the ordinal numbers.

[0053] The foregoing statements, as well as the following description of exemplary embodiments, do not constitute a waiver of certain embodiments or features.

[0054] The invention is explained in more detail below with reference to an embodiment shown in the drawing.

[0055] The drawings show: Fig. 1 a sectional view of a connection area of ​​two drill string sections, wherein a two-wire system is arranged in each of the two drill string sections; Fig. 2 an enlarged view of the Fig. 1 ; Fig. 3 an enlarged view of the Fig. 1 ; and Fig. 4 electrical conduction path.

[0056] Fig. 1 Figure 1 shows a cross-sectional view of the connection area between two drill rod sections 1 and 2 for drilling a borehole into the ground. The drill rod sections 1 and 2 are screwed together by means of a screw connection 3.

[0057] Each rod section 1, 2 has a two-conductor system 4, 5, which is arranged essentially centered in the cavity of the respective rod section 1, 2. The two-conductor system 4, 5 of a rod section 1, 2 is fixed by means of centering stars 6, 7, which are each inserted at one end of the rod sections 1, 2.

[0058] The two-conductor system 4, 5 comprises two conductors 15, 17 and 14, 16 respectively, with insulation 18 and 19 respectively between the conductors 15, 17 and 14, 16 respectively. The conductor 17 and 16 surrounds the conductor 15 and 14 respectively, and further insulation 20 and 21 are present around the conductor 17 and 16 respectively. The two-conductor systems 4, 5 each include a coaxial cable 12 and 13.

[0059] The two-wire system 5 of the in the Fig. 1 The right-hand rod section 2 has a socket 8 at its end, by means of which the inner conductor 14 of the coaxial cable 13 can be connected to the inner conductor 15 of the coaxial cable 12. The inner conductor 15 of the coaxial cable 12 has a plug 9 at its end, which fits into the socket 8 of the rod section 2. Fig. 1 The right linkage section 1 is inserted in a guided manner when screwing together the linkage sections 1, 2.

[0060] Two insulating sleeves 10 and 11 of the two-conductor system 5 are arranged around the socket 8, with insulating sleeve 10 located inside the outer insulating sleeve 11. Insulating sleeve 10 forms an inner insulating sleeve, while insulating sleeve 11 forms an outer insulating sleeve. Insulating sleeve 10 projects from the socket 8, and insulating sleeve 11 overlaps insulating sleeve 10.

[0061] The conductors 16 and 14 of the two-conductor system 5, as well as the conductors 15 and 17, are stripped of insulation at the ends of the two-conductor system 5 and 4, respectively, and are exposed without insulation 19, 21 and 18, 20. A counterpart 22, 23 is slid onto the insulation 21, 20. Furthermore, an insulating sealing element 24, 25 is slid onto the insulation. A ring 26, 27, which interacts with the counterpart 22, 23, is screwed to the counterpart 22, 23, whereby the insulating sealing element 24, 25 is pressed over a cone between the counterpart 22, 23 and the insulation 21, 20 and seals. The ring 26, 27 and the counterpart 22, 23 are electrically conductive.

[0062] The inner conductors 14 and 15 are surrounded circumferentially by insulation 28, 29 in the front area. Conductor 14 is crimped to socket 8 at its end, while conductor 15 is crimped to plug 9.

[0063] By means of the ring 26 and the counterpart 22, an electrical conduction path oriented against the connection direction is formed, which is directed "backwards" and is guided over the insulation 21 and over the conductor 14. From the counterpart 22, the electrical conduction path is guided back in the connection direction by means of an electrically conductive connecting sleeve 30. A wave spring 31 and a retaining ring 32 are provided to hold the electrically conductive connecting sleeve 30 in position.

[0064] The centering star 7 is in electrically conductive contact with the electrically conductive connecting sleeve 30. In the illustrated embodiment, the centering star 7 is in electrical contact with the linkage section 2, which is in electrically conductive contact with the linkage section 1. An electrical connection to the conductor 17 is established via the centering star 6. The further electrical conduction path leads via the counterpart 23 with the ring 27, 33.

[0065] An inner insulating sleeve 35 and an outer insulating sleeve 34 are arranged over the conductor 15, located in the front area. The inner insulating sleeve 35 engages in a projection of the inner insulating sleeve 10, sealingly. The outer insulating sleeve 34 engages in a projection of the outer insulating sleeve 11, sealingly with seals 36, 37. A pressure resistance of 150 bar can be achieved.

[0066] Fig. 4 Figure 41, 42 shows electrical conductor paths without reference symbols, indicated by dashed lines.

Claims

1. Two-conductor system (4, 5) for earth-boring drilling rod sections (1, 2) for forming a bore string for an earth-boring device, wherein the two-conductor system (4, 5) has an insulated composite of a first conductor (14, 15) and a second conductor (16, 17), and the first and second conductors (14, 15, 16, 17) are each exposed at one end from the composite in a connecting direction, wherein an electrical conduction path is formed for at least one of the conductors (14, 15, 16, 17), which extends away from the exposed end of the one conductor (14) via an insulation (21) of the one conductor (14) and / or the composite counter to the connecting direction, and from there passes in an insulated manner in the connecting direction at the end of the one conductor (14).

2. Two-conductor system (4, 5) according to claim 1, wherein the composite comprises a coaxial cable, and the two conductors (14, 15, 16, 17) are the inner and outer conductors of the coaxial cable.

3. Two-conductor system (4, 5) according to one of claims 1 or 2, wherein the exposed end of the one conductor (14) is contacted by means of an electrically conductive ring (26) adjacent to the exposed end, by means of which the insulation of the one conductor and / or the composite is sealed by pressing an insulating sealing piece (24) onto the insulation of the one conductor and / or the composite.

4. Two-conductor system (4, 5) according to claim 3, wherein the ring (26) can be screwed over or into a counterpart (22) that surrounds the insulation of the one conductor and / or the composite adjacent to the outer surface, and the insulating sealing piece (24) is pressed together with the ring (26) with an axial directional component onto the insulation of the one conductor and / or the composite during screwing.

5. Two-conductor system (4, 5) according to one of claims 3 or 4, as dependent on claim 2, wherein a front portion of the ring (26) is surrounded by an insulating sleeve (11) in the connecting direction.

6. Two-conductor system (4, 5) according to one of claims 1 to 5, wherein an electrically conductive connecting sleeve (30) surrounds an insulating sleeve (11) and extends over the ring (26) and / or the counterpart (22).

7. Two-conductor system (4, 5) according to one of claims 1 to 6, wherein a pressure relief valve is present for diverting an excess pressure.

8. Two-conductor system (4, 5) according to one of claims 1 to 7, wherein at least a portion of an exposed end of one of the conductors (14, 15, 16, 17) is circumferentially surrounded by an inner and an outer insulation sleeve (10, 11; 34, 35).

9. Earth-boring drilling rod section (1, 2) having a two-conductor system (4, 5) according to one of claims 1 to 8, wherein the two-conductor system (4, 5) is arranged, in particular by means of at least one centering star (6, 7), in the earth-boring drilling rod section (1, 2) substantially centrally in a cavity extending along the longitudinal axis of the earth-boring drilling rod section (1, 2).

10. Earth-boring drilling rod system having a plurality of earth-boring drilling rod sections (1, 2) according to claim 9, wherein the earth-boring drilling rod sections (1, 2) are connectable to one another to form a section of a drilling rod.

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