EP3496208B1 - Contact device and contact system for coaxial high voltage cable - Google Patents

Description

Area

The invention relates to a contact device for contacting a coaxial cable, the electrical conductor of which is surrounded by a shield which is designed as a tube, in particular as a corrugated tube. The invention further relates to a contact system which comprises a contact device according to the invention. The invention also relates to methods for producing a contact device according to the invention and a contact system according to the invention.

background

Contact devices and contact systems of the type mentioned above are required, for example, in cable fittings for a coaxial cable. A cable fitting is a component that terminates an electrical cable or connects it to another cable.

A cable fitting should create good electrical contact with the conductor and the shield of the coaxial cable and at the same time prevent moisture or dirt from getting between the components of the cable. In addition, electrical insulation between the electrical conductor and the shield of the coaxial cable must be ensured. A corrugated pipe is often used as a shield for this type of cable. Connecting such a high-voltage cable, for example to the housing of an electrical fitting or to another high-voltage cable, therefore requires contact to be made between both the cable core and the shield. When connecting to other components, the electrical conductor should also be guided to the corresponding component in a mechanically stable manner.

A common method for current-carrying contact of cables with metal corrugated sheaths (corrugated pipes) is welding or soldering metal contact elements. This type of contact is demanding and time-consuming. In addition, the quality of the contact depends heavily on the skills of the assembly personnel who make the contact. A consistently high quality of the contacts is therefore not easy to achieve with conventional contacting methods.

The US 2006/0054341 A1 relates to an electrical plug assembly with which an electrical cable is electrically connected and held in place in a distribution box, fuse box or the like. In order to secure the cable in the plug, a clamping screw is provided in one embodiment. In another embodiment, notched metal tongues prevent the cable from being pulled out of the plug. The holding means serve only to hold the cable, which engages with an outer sheath or insulation of the cable.

The WO 2017/030271 A1 describes a contact sleeve 500 for electrically connecting conductors, in particular multi-wire conductors. The contact sleeve is intended to prevent poor contact of the multi-wire conductor and thus undesirable heat development at the contact point.

The US 2008/261447 A1 discloses a connector for a coaxial cable. For assembly, the coaxial cable is inserted into the connector, where a needle-shaped section makes contact with the line of the coaxial cable. A clamping screw, which is provided with cutting edges, is screwed in and cuts through an outer jacket and a shield braid into the insulation layer of the cable.

The CN103 531 986B describes a device for contacting a high-voltage cable. To contact a shield made of aluminum wires, an inner ring is pushed between an inner sheath of the high-voltage cable and the shield. Then an outer ring is attached to the inner ring with screws, whereby the shield is clamped between the rings.

The US$2,947,800 concerns a cable bushing used in the electrical construction industry. The cable bushing comprises a tubular part which is provided with a clamping screw. A Spiral hose encloses cables that are fed into a control cabinet, for example. The clamping screw clamps the spiral hose in place. The tubular part has a thickening in the area of the clamping screw.

The CN104967087 describes a tubular part made of rubber that is pushed over a high-voltage line for testing purposes. The tubular part has threaded bushings into which clamping screws are screwed to contact a conductor.

The JP2010/180957 concerns the most economical connection of hollow concrete posts. For this purpose, a pipe is fastened over the posts to be connected using clamping screws.

The EN 10 2008 025 428 A1 relates to a connecting terminal for a conductor wire. The connecting terminal comprises a clamping body which consists of a bent sheet metal part. A hole for a clamping screw is made through two wall sections lying one above the other using a flow forming process. This creates collar-shaped projections on the top of the upper wall section and the bottom of the lower wall section, whereby the length of the threaded hole is greater than the wall thickness of the wall sections.

Proceeding from this, it is an object of the present invention to provide a contact device which overcomes or at least improves one or more of the problems mentioned above.

Summary of the invention

To solve this problem, the invention proposes a contact device according to the appended claims.

A clamp contact between the cable shield and the contact tube has the advantage that this type of contact is easy to produce compared to welding or soldering and also offers advantages in terms of work safety. At the same time, it is possible to achieve a more uniform quality of electrical contacts with clamp contacts, which hardly depends on the qualifications and skills of the assembly personnel. Another advantage of clamp contacts is that almost any metallic material can be combined with one another to create a to establish electrical contact. Furthermore, only simple tools are required to establish a terminal contact.

The threaded holes are produced using a friction-flow-drilling process, so that each threaded hole has an annular bead (201) on the inside of the contact tube. This has the advantage that a greater material thickness is available for the thread compared to the wall thickness of the contact tube, and thus the length of the threaded hole is greater and a better hold of the clamping screw in the contact tube is achieved. This makes it possible, for example, to transmit greater clamping forces with the clamping screws.
The threaded holes are arranged with one clamping screw each on at least two circular lines on the circumference of the contact tube, evenly distributed on each circular line, with the threaded holes on adjacent circular lines being offset from one another in the circumferential direction. This ensures that there are no structural weak points in the jacket of the contact tube. In addition, the contact pressure of the clamping screws on the cable shield is evenly distributed.
The arrangement of the clamping screws on circular lines is advantageous because a cable can be easily arranged centrally in the contact device. In the event of a short circuit between the cable conductor and the contact tube, this arrangement has the advantage that the resulting electrodynamic forces cancel each other out, limiting the mechanical load on the contact device.
Conveniently, the contact tube of the contact device can have a fastening flange at one end in order to fasten the contact device, for example, to an electrical system or a cable fitting.
In a further development of the invention, the contact tube has at least one contact point that enables the connection of cables or strands, e.g. for grounding the contact device. In this case, the contact point can expediently be designed as a pin that has an internal thread or an external thread in order to attach a cable lug or the like there. It is also conceivable that the pin has a threaded pin with an external thread for fastening further contact elements.
In one embodiment, the cable shield is designed as a smooth tube sheath or a corrugated tube sheath. The type of sheath chosen depends on the application. In principle, a corrugated tube sheath is more flexible than a smooth tube sheath.

Short description of the drawing

Fig. 1

eine perspektivische Ansicht einer erfindungsgemäßen Kontaktvorrichtung;

Fig. 2A

einen Querschnitt der Kontaktvorrichtung aus Figur;

Fig. 2B

ein vergrößerter Ausschnitt aus Figur 2A;

Fig. 3

den Aufbau eines Kabels, das mit der Kontaktvorrichtung kontaktiert wird;

Fig. 4

die Kontaktvorrichtung aus Figur 1 in einer Draufsicht mit einem montierten Kabel;

Fig. 5

ein Flussdiagramm mit den Verfahrensschritten zur Herstellung einer erfindungsgemäßen Kontaktvorrichtung; und

Fig. 6

ein Flussdiagramm mit den Verfahrensschritten zur Herstellung eines erfindungsgemäßen Kontaktsystems.

The invention is explained in more detail below using an embodiment as an example with reference to the accompanying figures. All figures are purely schematic and not to scale. They show:

Fig.1

a perspective view of a contact device according to the invention;

Fig. 2A

a cross-section of the contact device of Figure;

Fig. 2B

an enlarged section of Figure 2A ;

Fig.3

the structure of a cable that is contacted with the contact device;

Fig.4

the contact device Figure 1 in a top view with a mounted cable;

Fig.5

a flow chart with the process steps for producing a contact device according to the invention; and

Fig.6

a flow chart with the process steps for producing a contact system according to the invention.

Identical or similar elements are provided with identical or similar reference symbols in the figures.

Example

Figure 1 shows a perspective view of a contact device 100, which has a contact tube 101. In different embodiments, the contact tube 101 has a diameter of 10 - 20 cm and a height of 10-30 cm. If necessary, these dimensions can also be chosen differently in order to adapt the contact tube 101 to specific applications. Figure 1 The lower end of the contact tube 101 is A flange 102 is welded to the contact tube. The flange 102 is provided along its circumference with fastening holes 103 for receiving fastening screws (not shown) in order to fasten the contact device to an electrical device, such as a transformer or a cable set (in Figure 1 not shown). The contact tube 101 and the flange 102 are made of aluminum or an aluminum alloy. In principle, other metals can also be used, for example copper or other highly conductive metals.

In the casing 104 of the contact tube 101, threaded holes 106A and 106B are provided, each of which accommodates a clamping screw 107A or 107B. The threaded holes 106A are distributed along a circular line 108A and the threaded holes 106B are distributed along a circular line 108B in the circumferential direction at a uniform distance. Although in Figure 1 two circular lines 108A and 108B are shown, in other embodiments the threaded holes can also be arranged on just a single circular line or on more than two circular lines. The relevant design of the contact device 100 according to the invention depends on the respective application, in particular on how many clamping screws are required.

In any case, the threaded holes are preferably arranged offset from each other on different circular lines. Figure 1 In the embodiment shown, a threaded hole 106B on the circular line 108B is located in the circumferential direction exactly between two threaded holes 106A that are located on the circular line 108A. This prevents the casing 104 of the contact tube 101 from being structurally weakened along axial directions by holes arranged one behind the other.

The contact device 100 also has a pin 111 projecting in the radial direction, which is welded to the casing 104 of the contact tube at a certain distance between the flange 102 and the circular line 108B and provides a contact point for connecting another cable For this purpose, the pin 111 has a central threaded hole 112 in order to screw on, for example, a cable lug of the additional cable.

In the Figure 1 The screws 107A, 107B shown are provided with a hexagon socket. In principle, other types of screws can also be used for the present invention, in particular screws with a shear head.

Figure 2A shows a cross section through the contact tube 101 at the level of the circular line 108B. In this view, it can be clearly seen that the threaded holes 106B are distributed at equal intervals on a circumferential line of the casing 104 of the contact tube 101.

Figure 2B shows an enlarged section of Figure 2A and illustrates a manufacturing-related special feature of the contact tube 101. The bores for the threaded holes are produced by a friction-flow-drilling process. In this process, a rapidly rotating steel tool is pressed in a radial direction onto the casing 104 of the contact tube 101. The frictional heat causes the metal to flow, which displaces the material under the rotating tool. In this process, beads 201 form around the respective borehole in the contact tube 101, which are directed inwards in the radial direction in the contact tube 101. This creates a borehole whose length I is greater than the thickness d of the casing 104 of the contact tube 101. A thread is cut into the borehole to produce a threaded hole, for example a threaded hole 106A or 106B. The length of the threaded hole corresponds to the length l of the borehole. In contrast, the length of a threaded hole conventionally produced with a twist drill would correspond to the length of the jacket thickness d of the contact tube 101. In comparison, the threaded hole in the contact tube according to the invention is mechanically more stable due to its greater length, so that it is possible to exert comparatively greater clamping forces with the clamping screws 107A and 107B.

Figure 3 shows schematically the structure of a high-voltage cable 300, which has an outer jacket 301. A shield 302 surrounds a multi-core conductor 303, which is formed from individual wires 304. The individual wires 304 are surrounded by a sheath 306, which bundles the individual wires 304 to form the conductor 303. The shield 302 is designed as a corrugated tube. The electrical conductor 303 is surrounded by a dielectric 307, which is followed by an insulation layer 308, which lies between the dielectric 307 and the shield 302. In other embodiments, the conductor 303 is designed as a solid individual conductor.

Figure 4 shows a cross-sectional view through the contact device 100 with a mounted HV coaxial cable 301, wherein the cut surface is taken along the line 4-4 in Figure 1 It should be noted that in Figure 4 in contrast to Figure 1 the screws 107A and 107B are screwed into the threaded holes 106A and 106B of the contact tube 101, respectively. The outer jacket 301 is removed from the cable 300 by a length that corresponds approximately to the length of the contact tube 101 plus the length that is required to connect the cable 301 inside an electrical device to a connection provided for it. The corrugated tube 302 is exposed inside the contact device 100. The screws 107A and 107B are screwed in, clamp the corrugated tube 302 essentially in the middle of the contact tube 101 and establish an electrically conductive contact between the contact tube 101 and the corrugated tube 302. This arrangement also has the advantage that in the event of a short circuit and high current flows through the conductor 303 and the contact tube 101, the electrodynamic forces that arise cancel each other out. In particular, the arrangement has the advantage that reproducible electrical contacts between the corrugated tube 302 and the contact tube 101 can be produced in a simple manner.

The arrangement of the clamping screws 107A and 107B, which are evenly spaced on a circular line 108A or 108B and offset from each other on different circular lines, also leads, among other things, to the Clamping forces on the screen 302 are distributed comparatively evenly, which has a positive effect on the dimensional stability of the screen 302.

In Figure 5 a flow chart with the essential process steps for producing a contact tube 101 according to the invention is shown schematically. In a first step S1, a cylindrical tube made of, for example, aluminum or an aluminum alloy is provided. In a next step S2, radial holes are drilled into the casing 104 of the contact tube 101, which are evenly spaced on a circular line on the circumference of the casing 104. The holes are preferably drilled using a friction-flow-drilling process in which a rapidly rotating steel tool is pressed onto the casing 104. As a result, the material of the casing changes into a flowable state, which on the one hand creates a hole and on the other hand creates a bead 201 surrounding the hole on the inside of the casing. Threads are cut into the holes thus formed, so that threaded holes are created into which the contact screws 107A and 107B are screwed. If necessary, a flange 102 can be welded to the contact tube 101 before or after the threaded holes 106A and 106B are made.

The contact device produced in this way is used to produce a contact system. The process steps for producing the contact system are shown schematically in a flow chart in Figure 6 shown. In a first step S10, a contact device 100 according to the invention is provided. Then, in a step S11, the outer jacket 301 is removed from the cable 300 in order to expose the shield 302 designed as a corrugated tube. In a step S12, the cable 300 is inserted into the contact device 100 with the end at which the corrugated tube 302 is exposed. Finally, in step S13, the clamping screws 107A and 107B are screwed in in order to contact the corrugated tube 302 in a substantially central position in the contact tube 101.

To complete the contact, another cable can be connected to pin 111, which can be fastened with a screw.

List of reference symbols

100

Contact device

101

Contact tube

102

Mounting flange

103

Mounting holes

106A, 106B

Threaded holes

107A, 107B

Clamping screw

108A, 108B

Circle line

111

cone

112

threaded hole

113

External thread

201

Bulges

300

Cable

301

outer insulation jacket

302

umbrella

303

multi-core conductor

304

Single wires

306

Covering

307

dielectric

308

Buffer layer

Claims (5)

1. A contact device (100) for a high-voltage cable (300) having an insulated electrical conductor (303), which is surrounded by a screen (302) designed as a tube, wherein the contact device has a contact tube (101), which accommodates the cable (300),

   wherein, in the contact tube (101) several threaded holes (106A, 106B) are each provided with a clamping screw (107A, 107B), characterized in

   that the threaded holes (106A, 106B) are produced by a friction-flow drilling process, so that each threaded hole (106A, 106B) has an annular bead (201) on the inside of the contact tube, that the threaded holes (106A, 106B) are arranged on at least two circular lines (108A, 108B) on the circumference of the contact tube (101) uniformly distributed on each circular line (108A, 108B),

   that the threaded holes (106A, 106B) are arranged offset relative to one another on adjacent circular lines in the circumferential direction and

   that the clamping screws (107A, 107B) are suitable for contacting the screen (302) of the cable (300).
2. The contact device according to claim 1, characterized in that the contact device has at least one contact point, which enables the connection of cables or stranded wires.
3. The contact device according to claim 2, characterized in that the contact point is designed as pin (111), which has an internal thread or an external thread.
4. A contact system, which has a contact device (100) according to any one of the preceding claims and a high-voltage cable (300), which has an electrical conductor (303), which is surrounded by a screen (302), which is designed as a tube.
5. The contact system according to claim 4, characterized in that the screen (302) is a smooth tube jacket or a corrugated tube jacket.

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