Contact terminal, use thereof and arrangement comprising such a contact terminal, an electrical cable and a support structure

Abstract

Contact terminal for fastening and electrically connecting a cable (23) having electrical insulation (22) to an electrically conductive support structure (21), which contact terminal (1) - a base body (2) with a cable receptacle (5) through which a cable (23) to be fastened can be passed, and with at least one clamping contact element (6, 12) which can be positioned under preload against the supporting structure (21), - at least one insulation penetration element (12, 13) in electrical connection with a clamping contact element and comprising at least one penetration body for contacting an electrical conductor (24) located below the insulation (22) of the cable (23) and - a clamping device (7) for applying a preload to the at least one clamping contact element (6, 12) relative to the supporting structure (21) and for contacting the at least one electrical conductor (24) of a cable (23) by pressing the insulation penetration member (12, 13) into the insulation of the cable (23).

Description

[0001] The invention relates to a contact clamp for fastening and electrically connecting a cable to an electrically conductive support structure. The invention further relates to the use of such a contact clamp. The invention also relates to an arrangement comprising such a contact clamp, an electrical cable provided with external electrical insulation, and a support structure.

[0002] Such contact terminals are used, for example, to connect the shielding beneath the outer insulation of shielded electrical cables to a supporting structure that acts as a ground. This shielding is made of interwoven strands of wire, with electrical insulation interposed to surround the actual electrical conductor(s). The supporting structure itself is electrically conductive, and in the case of a ground (in the electrical sense), its electrical conductivity is sufficient for it to function as a ground. Sometimes, it is even sufficient if only the surface of such a supporting structure is electrically conductive. Typically, these supporting structures are made of a type of steel commonly used for this purpose.The surfaces may be galvanized to provide corrosion protection.

[0003] To connect the electrically conductive braid of a shielded electrical cable to ground, the first step is to remove the outer insulation. A terminal block is then positioned on this stripped section, which can be an end section or a section at any point along the cable's length. The terminal block is then clamped to the braid and connected to ground.

[0004] Contact clamps are also used to attach grounding cables to a support structure and connect them electrically. In some cases, these grounding cables are uninsulated. A contact clamp then creates the necessary pre-tension between the grounding conductor and the support structure to ensure a reliable electrical connection. Such uninsulated grounding cables or conductors are frequently used in railway installations. Unfortunately, cable thefts are a recurring problem on railway lines, often resulting in the closure of affected tracks. The uninsulated grounding conductors are the ones that are removed and stolen. These cables are highly sought after because of their lack of insulation, as they can be reused, particularly melted down, without requiring any further treatment.

[0005] Based on the aforementioned prior art, the invention aims to propose a contact terminal for fastening and electrically connecting an electrical cable to an electrically conductive support structure, thereby simplifying the electrical connection of an electrically insulated cable to a support structure with conductivity sufficient for grounding purposes. This would also make it possible to use insulated cables as grounding conductors in railway systems without increasing installation effort. Furthermore, it would be desirable to have a contact terminal that would also simplify the electrical grounding of a shield in an insulated electrical cable.

[0006] According to the invention, these problems are solved by a contact clamp for fastening and electrically connecting a cable having electrical insulation to an electrically conductive support structure, which contact clamp - a base body with a cable receptacle through which a cable to be fastened can be passed, and with at least one clamping contact element that can be positioned under preload against the supporting structure, - at least one insulation penetration element, electrically connected to a clamping contact element and comprising at least one penetration body, for contacting an electrical conductor located below the insulation of the cable and - comprising a clamping device for applying a preload to the at least one clamping contact element relative to the supporting structure and for contacting the at least one electrical conductor of a cable by pressing the insulation penetration element into the insulation of the cable.

[0007] This contact terminal, which can also be referred to as a grounding terminal if a ground connection is provided, comprises a base body, at least one clamping contact element, at least one insulation penetration element, and a clamping device. The base body provides a cable receptacle through which a cable to be fastened can be passed. Such a base body is, for example, U-shaped, as shown in one embodiment. In this case, the contact terminal is designed like a known clamp used to fasten cables to a support structure. Associated with the base body is at least one clamping contact element, which can be pre-tensioned against the support structure by the clamping device. Thus, the clamping contact element provides the electrical connection between the contact terminal and the support structure.When the contact clamp is designed as a U-bolt clamp, the anchoring elements, which can have different shapes, typically serve as the clamping contact element(s).

[0008] Furthermore, this contact terminal has at least one insulation penetration element. This insulation penetration element serves to contact an electrical conductor located beneath the outer insulation of a cable. This conductor can be one or more electrical conductors enclosed in a braided shield, or it can be individual wires (strands). Such an insulation penetration element is electrically connected to a clamping contact element responsible for the electrical transition to the supporting structure. For electrical contacting the electrical conductor located beneath the insulation, such an insulation penetration element has at least one penetration point. This point is typically nail- or tooth-shaped, thus possessing a penetration tip.When a corresponding clamping force is applied via the clamping device, at least one penetration element is pressed into the insulation of the electrical conductor to contact the conductor located beneath the insulation. Preferably, such an insulation penetration element has several penetration elements arranged in a row following the longitudinal extent of the cable to be contacted. These are typically designed as a row of teeth. Such an insulation penetration element can also have several such rows of penetration elements. These are then arranged at a distance from each other in the direction of the width of the cable receptacle. In such a design, according to one embodiment, the longitudinal axes of the penetration elements of the two rows of penetration elements are arranged with their free ends inclined relative to each other.The tips of the penetration bodies of the two rows of penetration bodies then point at least approximately in the direction of the center of an electrical cable located in the cable receptacle.

[0009] A clamping device is also part of the contact clamp. This device serves to clamp the at least one clamping contact element against the supporting structure and simultaneously to bring about electrical contact with the electrical conductor by pressing the penetration element(s) into the cable insulation until they make contact with the underlying electrical conductor. The clamping device advantageously has a single clamping actuator to effect both the clamping of the at least one clamping contact element against the supporting structure and the electrical contact with the cable's electrical conductor. According to one embodiment, a clamping screw serves as the clamping actuator. In a U-shaped design of the base body, the clamping screw, according to one embodiment, extends through the web connecting the two legs and engages an internal thread complementary to its external thread.This can be cut into the opening of the web or provided by a weld nut positioned on or in an opening of the web. It is also quite possible to design the complementary internal thread by means of a flare extending towards the cable receptacle, which provides the access opening into which the internal thread is cut.

[0010] With the exception of the clamping device, a contact terminal can be manufactured cost-effectively from stamped and bent parts. This also applies to the penetration element(s). If several penetration elements are arranged in a row, they can easily be produced as toothed rows using a stamping and bending process, pointing into the cable receptacle. The term "stamped part" as used in this context encompasses not only the stamping of individual parts but also all other methods of producing a base circuit board with the required outer contour, such as laser cutting.

[0011] With such a contact clamp, the clamping process simultaneously establishes electrical contact with the electrical conductor located beneath the outer insulation of an electrical cable and fastens the contact clamp and cable to the supporting structure. When designed as a U-bolt clamp, it is therefore just as easy to handle as a standard clamp, despite establishing an electrical connection between an electrical conductor within the cable and a supporting structure.

[0012] Ultimately, any structure that is electrically connected to ground can serve as a support structure. For example, a rung of a cable ladder can be used. Such rungs typically have a C-shaped cross-section. In this configuration, the contact clamp can be designed like a U-bolt clamp. The end sections of the legs of the base body are then designed like anchoring hooks that engage in at least one undercut created by the C-shaped profile. With their edge facing the cable receptacle, these hooks then act as clamping contact elements against the inside of the undercut(s) when the contact clamp is attached. Such an anchoring element can be designed as a single- or double-sided hook. It is also quite possible for the anchoring element to be designed like a hammerhead.If the contact clamp has a U-shaped base body, it is preferred that both ends opposite the web supporting the clamping device are designed as anchoring elements, for example in the form of anchoring hooks.

[0013] Such an insulation penetration element can, for example, be designed as a clamping plate, such as when the cable receptacle of the base body is U-shaped. This clamping plate, acting as an insulation penetration element, is adjustable or movable relative to the legs of the base body in the longitudinal direction of the base body and is guided along these legs. The penetration element(s) are arranged on its side facing the cable receptacle. On its side opposite the at least one penetration element, such an insulation penetration element, designed as a clamping plate, is connected to the supporting structure with at least one section that can be adjusted under preload and fitted with a contact clamp.If the supporting structure is the rung of a cable ladder, this side of the insulation penetration element acts as a clamping contact element against the top of the rung, specifically in those sections adjacent to the rung's opening. Thus, such an insulation penetration element acts against the outer surface of the rung's opening-bounding sections, against whose underside the anchoring element(s) of the base body act. Therefore, this side of the insulation penetration element constitutes a clamping contact element responsible for the necessary electrical contact with the supporting structure.

[0014] In an alternative design, or preferably also as a supplement to such a contact clamp as described above, the insulation penetration element is designed as a contact plate. With a U-shaped base body, this contact plate is held and guided on the legs so that it is adjustable or movable along its longitudinal extent and relative to it. This insulation penetration element, designed as a contact plate, is typically electrically connected to the base body via the clamping device. The base body, in turn, has at least one anchoring element for engaging at least one section of the support structure, and electrical contact with the support structure is then established via this anchoring element when a contact clamp is attached to the support structure.

[0015] When designing a contact terminal with an insulating penetration element designed as a contact plate, it is advantageous for the clamping device to have a pressure plate acting on this insulating penetration element. The clamping force of the clamping device is then distributed via the pressure plate over a larger surface area of ​​the insulating penetration element serving as the contact plate. This also improves the electrical contact. It is also possible to use such a pressure plate itself as the insulating penetration element. In this case, the pressure plate carries at least one penetration element on its side facing the cable entry point.

[0016] If a clamping screw is provided as the clamping actuator of the clamping device, it typically acts on a pressure plate which is connected to the screw shaft in a rotationally decoupled manner.

[0017] The contact terminal according to the invention is equally suitable for AC and DC voltage applications.

[0018] The invention is described below with reference to an exemplary embodiment and the accompanying figures. These show: Fig. 1: A perspective view of a contact terminal according to the invention, Fig. 2: the contact terminal of the Fig. 1 from a different perspective, Fig. 3: The contact terminal of the preceding figures in a side view, Fig. 4: Two insulation penetration elements of the contact terminal of the preceding figures in a separate view, Fig. 5: the contact terminal according to the invention, connected to a support structure and Fig. 6: a side view of the arrangement of Fig. 5 with a view in the longitudinal direction of the supporting structure.

[0019] A contact terminal 1 serves to fasten and electrically connect a cable with external electrical insulation to an electrically conductive support structure. In the illustrated embodiment, the contact terminal 1 is designed as a grounding terminal to connect an electrically insulated grounding cable to the earth provided by the support structure. The contact terminal 1 is essentially constructed like a U-shaped clamp and comprises a U-shaped base body 2. The base body 2 has two legs 3, 3.1, which are connected to each other by a web 4. A cable receptacle 5 is located between the two legs 3, 3.1. A cable to be connected to and fastened to a support structure with the contact terminal 1 passes through the cable receptacle 5. The free end sections of the legs 3, 3.1 are each designed in a hook shape to form an anchoring structure.Regarding leg 3, the hook structure is identified by reference symbol 6. Due to the perspective, the hook structure of leg 3.1 is not clearly visible. The hook structures 6 of both legs 3 and 3.1 are oriented in the same direction and serve to engage behind a component of a supporting structure.

[0020] Instead of the hook structures 6 shown in the figures, these can also be realized by other anchoring structures.

[0021] A clamping device, designated by reference numeral 7, is attached to the base body 2. The clamping device 7 comprises a clamping screw 8, the shank 9 of which extends through the web 4 of the base body 2. A pressure plate 10 is attached to the base of the clamping screw 8 in a rotationally decoupled manner. The thread of the screw shank 9 engages with a corresponding internal thread via a sleeve-like crimp 11 oriented towards the cable receptacle 5. By turning the clamping screw 8, the pressure plate 10 can be adjusted in the direction of the longitudinal extension of the legs 3, 3.1. In the illustrated embodiment, the pressure plate 10 has a saddle-shaped cross-section and extends through the cable receptacle 5. The width of the pressure plate 8 secures it against rotation between the legs 3, 3.1 of the base body 2.When the clamping device 7 is actuated, the pressure plate 10 can be actuated in the direction of the cable receptacle 5 to clamp a cable located thereon and also to release it.

[0022] The contact terminal 1 of the illustrated embodiment also includes two insulation penetration elements 12, 13. The two insulation penetration elements 12, 13 are guided on the legs 3, 3.1 and are adjustable along the longitudinal extent of the legs 3, 3.1. The insulation penetration element 12 limits the cable receptacle 5 in the perspective view of the Fig. 1 on the underside. The insulation penetration element 13 limits the cable receptacle 5 on the top side.

[0023] The insulation penetration element 12 is designed like a clamping plate and has two rows of penetration elements 14, 14.1 on its side facing the cable receptacle 5. The penetration elements of the rows 14, 14.1 are tooth-shaped and each has a point directed towards the cable receptacle 5. The rows of penetration elements 14, 14.1 are inclined relative to each other with respect to the points of their penetration elements. Thus, the longitudinal axes of the penetration elements of the rows 14, 14.1 point towards the center of a cable to be fastened with the contact terminal 1 and electrically connected to a support structure. The insulation penetration element 12 is a stamped and bent part, from whose base plate 15 the rows of penetration elements 14, 14.1 are bent outwards towards the cable receptacle 5.The openings in the base plate 15 created in this way each represent a passage 16 for a leg 3, 3.1. The passages 16 are bounded on the outside with respect to the respective leg 3, 3.1 by a web 17. In the illustrated embodiment, the webs 17 are not parallel to the surface of the respective leg 3, 3.1, but form an angle of approximately 10° to 20° with it. The distance between the two webs 17 of the insulation penetration element 12 is thus defined by their upper inner edges facing each other. This distance is designed so that the insulation penetration element 12 is held frictionally on the legs 3, 3.1, whereby this frictional engagement only acts to the extent that, when handling the contact terminal 1 to connect it to a support structure, the insulation penetration element 12 does not slip off the base body 2 or its legs 3, 3.1 on its own.The pressure plate 10, whose width is designed with only a clearance between the inner sides of the legs 3, 3.1, ensures that essentially only the ends of the legs 3, 3.1 are responsible for applying the preload to hold the insulation penetration member 12 to the base body 2.

[0024] The contact terminal 1 shown in the figures is designed like a clamp to be attached to a rung of a cable ladder as an exemplary support structure. The longitudinal extent of the insulation penetration element 12 (extending towards the cable receptacle 5) is therefore designed so that the insulation penetration element 12 rests on the two surface sections of such a rung that enclose a mounting groove. The webs 17 also carry a projection 18 pointing towards the respective hook structure 6, which engages in the opening of the mounting groove of such a rung and thus defines the position of the contact terminal 1 on such a rung. The width of the projection 18 corresponds, less a certain clearance, to the clear width of the mounting groove of such a rung.

[0025] The insulation penetration element 13 limits the cable receptacle 5 on the upper side and has a saddle-shaped cross-sectional geometry (see Fig. 2) The insulation penetration member 13 also has two rows of penetration elements 19, 19.1 on its underside, and thus on the side facing the cable receptacle 5. These are designed in the same way as the rows of penetration elements 14, 14.1 described above for the insulation penetration member 12. The insulation penetration member 13 is also guided along the longitudinal extent of the legs 3, 3.1 of the base body and is adjustable relative to them in the direction of their longitudinal extent. The ends of the insulation penetration member 13 that point in the longitudinal extent of a cable inserted into the cable receptacle 5 are bent upwards in a manner known per se. In the illustrated embodiment, the insulation penetration member 13 is also a stamped and bent part.

[0026] The hook structure 6 of the contact terminal 1 is shown in the side view of the contact terminal 1 in the Fig. 3 clearly visible.

[0027] The base body 2 and the clamping device 7 with its clamping screw 8 and its pressure plate 10 can be a standard U-bolt clamp that has been upgraded by the two insulation penetration elements 12, 13.

[0028] The two insulation penetration bodies 12, 13 are in Fig. Figure 4 shows a perspective view of the two insulation penetration elements 12 and 13. The previously described design is more clearly visible therein. With regard to the insulation penetration element 13, the central part of the saddle-shaped design, formed by a curved pressure rib 20, is now discernible, something not apparent in the preceding figures. The pressure plate 10 of the clamping device 7 exerts a surface contact on its convexly curved upper surface.

[0029] The individual components of the contact terminal 1, namely the base body 2 and the two insulation penetration elements 12, 13, are manufactured as stamped and bent parts from stainless steel.

[0030] The penetration sections 19, 19.1 of the insulation penetration element 13, like those of the insulation penetration element 12, serve to contact an electrical conductor of an electrical cable located beneath insulation. The length of the penetration sections 14, 14.1; 19, 19.1 is designed to allow them to penetrate the cable insulation and be pressed sufficiently far into or between the strands of the electrical conductor. The insulation penetration element 13 is electrically connected to the base body 2 via the clamping device 7 through the flat contact between the pressure rib 20 and the pressure plate 10. Additionally, a contact may be provided between the insulation penetration element 13 and one or both legs 3 or 3.1. However, the defined electrical connection is made via the clamping device 8 acting on the pressure rib 20.

[0031] The insulation penetration element 12 is designed to be directly supported on a support structure with its side opposite the penetration element rows 14, 14.1. This allows for the contact of an electrical conductor located below insulation of a cable inserted into the cable receptacle 5 with the support structure directly via the insulation penetration element 12 itself.

[0032] Fig. Figure 5 shows the contact terminal 1 mounted and attached to a rung 21 of a cable ladder (not shown in detail) as an exemplary support structure. It is understood that the rung 21 could also be a component of a different support structure. A cable 23, provided with electrical insulation 22, is inserted into the cable receptacle 5 of the contact terminal 1; in the illustrated embodiment, this is a grounding cable. In the Fig. In the arrangement shown in Figure 5, the contact clamp 1 is tensioned and thus attached to the rung 21. The penetration element rows 14, 14.1 of the insulation penetration element 12 and those of the insulation penetration element 13 are pressed through the insulation 22 of the cable 23 and contact cable strands 24 located below the insulation 22 with their pointed sections. The hook structures 6 of the legs 3, 3.1 engage behind the mounting groove 25 of the C-shaped profiled rung 21.

[0033] The clamping and connection are better shown in the side view of the Fig. 6 of the arrangement of Fig. 5 recognizable. The hook structures 6 of the legs 3, 3.1 engage under and behind the in Fig.The left section of the rung 21, which defines the mounting groove 25, is shown in Figure 6. Due to the tension applied by the clamping device 7, the hook structure 6 acts under preload against the leg 26, which is bent into the interior of the rung 21 and defines the mounting groove 25. Thus, the sections of the hook structure 6 that contact the free edge of the leg 26 serve as the clamping contact element. In this way, a reliable electrical contact is established between the base body 2, and therefore the insulation penetration body 13, and the rung 21 as the support structure. The insulation penetration element 12 rests with its outer surface, facing away from the cable 23, on the top surface of the rung 21, thereby ensuring the electrical transition into the rung 21 as the support structure. For the insulation penetration body 13, the sections in contact with the surface of the rung 22 are therefore the clamping contact element.The engagement of the extension 18 of the bridge 17 for positioning the contact terminal 1 in the opening of the mounting groove 25 of the rung 21 can be clearly seen.

[0034] A special feature of the contact clamp 1 is that a single operation, namely the tightening of the clamping device 7, simultaneously establishes electrical contact with the insulated electrical conductor of a cable and clamps it to a support structure. The assembly effort required to create an electrically conductive connection, for example, a grounding connection between an insulated grounding cable or earth conductor and a support structure, is therefore no greater than the effort required to fasten or fix such a cable to a support structure using a clamp.

[0035] Even though a clamping screw is described in the figures as an exemplary embodiment of such a clamping device, it can also be designed differently, for example as a locking clamping device. Such a clamping device can be advantageous for a contact terminal 1 that is not designed to be released. The clamping itself can then be carried out, for example, by means of a separate collet as a clamping actuator.

[0036] The invention has been described using exemplary embodiments. Without departing from the scope of protection described by the applicable claims, numerous further embodiments of the inventive concept would be apparent to a person skilled in the art, without these needing to be explained in more detail within the scope of these explanations. Reference symbol list 1 contact terminal 2 basic shapes 3, 3.1 Thigh 4 Bridge 5 cable holder 6 hook structure 7 Clamping device 8 clamping screws 9 shaft 10 printing plate 11. Flanging 12 Insulation penetration element 13 Insulation penetration element 14, 14.1 Penetrating body series 15 Base plate 16. Access 17 Bridge 18 continuation 19, 19.1 Penetrating body series 20 pressure bridge 21 rungs 22 Insulation 23 cables 24 strands of cable 25 Mounting groove 26 thighs

Claims

[1] Contact terminal for fastening and electrically connecting a cable (23) having electrical insulation (22) to an electrically conductive support structure (21), which contact terminal (1) - a base body (2) with a cable receptacle (5) through which a cable (23) to be fastened can be passed, and with at least one clamping contact element (6, 12) which can be placed under prestress against the support structure (21), - at least one insulation penetration member (12, 13) which is electrically connected to a clamping contact element and comprises at least one penetration body for contacting an electrical conductor (24) located below the insulation (22) of the cable (23) and - a tensioning device (7) for applying a prestress to the at least one tensioning contact element (6, 12) relative to the support structure (21) and for contacting the at least one electrical conductor (24) of a cable (23) by pressing the insulation penetrating member (12, 13) into the insulation of the cable (23). [2] Contact terminal according to claim 1 characterized by in that the base body (2) is U-shaped and an insulation penetrating member (12) is provided on the legs (3, 3.1) in the direction of the longitudinal extent of the legs (3, 3.1) which is adjustable relative to these, delimiting the cable receptacle (5), which carries the at least one insulation penetrating body on its side facing the cable receptacle (5) and with at least a section of its opposite side when the contacting terminal (1) is fastened to a support structure (21), can be adjusted under pretension against the support structure (21), serves as a clamping contact element. [3] Contact terminal according to claim 1 or 2, characterized by that the base body is U-shaped and an insulation penetrating member (13) is provided on the legs (3, 3.1) in the direction of the longitudinal extent of the legs (3, 3.1) which is adjustable relative to these, delimiting the cable receptacle (5), which carries at least one penetrating body on its side facing the cable receptacle (5) and is electrically conductively connected to the base body (2) by means of the tensioning device (7), and that the base body (2) has at least one anchoring element (6) for engaging behind a section of the support structure (21), which serves as a tensioning contact element when the contacting terminal (1) is fastened to a support structure (21) and is pretensioned against the support structure (21). [4] Contact terminal according to claim 3, characterized bythat each leg (3, 3.1) of the base body (2) is designed as an anchoring element at the end in the manner of an anchoring hook (6). [5] Contact terminal according to claim 3 or 4, characterized by that the clamping device (7) has a pressure plate (10) acting on an insulation penetrating member (13). [6] Contact terminal according to one of claims 1 to 5, characterized by that the clamping device (7) comprises a clamping screw (8) acting on a pressure plate (10). [7] Contact terminal according to claim 6, characterized by that the base body (2) is U-shaped, the clamping screw (8) passes through the web (4) connecting the two legs (3, 3.1) of the base body (2) and, in conjunction with the passage, meshes with an internal thread complementary to the thread of the clamping screw (8). [8] Contact terminal according to one of claims 1 to 7, characterized bythat the insulation penetrating member(s) (12, 13) comprise a plurality of penetrating bodies arranged in a row and designed in the manner of teeth. [9] Contact terminal according to claim 8, characterized by that an insulation penetrating member (12, 13) has at least two rows of penetrating bodies (4, 14.1; 19, 19.1) arranged at a distance from one another, wherein the penetrating bodies of the two rows of penetrating bodies (4, 14.1; 19, 19.1) are inclined towards one another with their longitudinal axes towards their free ends. [10] Contact terminal according to one of claims 1 to 9, characterized by that the base body (2) and the at least one insulation penetrating member (12, 13) are stamped and bent parts. [11] Contact terminal according to one of claims 1 to 10, characterized by that the contact terminal (1) is used as an earthing terminal. [12] Arrangement comprising a contact terminal (1) according to one of claims 1 to 11, an electrical cable (23) with an outer insulation and a support structure (21), characterized by that the contacting terminal (1) is fixed to the support structure (21) with an electrical cable (23) passing through its cable receptacle (5) after actuation of the tensioning device (7), by which tensioning the at least one penetrating body of the at least one insulation penetrating member (12, 13) is pressed through the outer insulation (22) of the electrical cable (23) and contacts an electrical conductor (24) located underneath.

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