CABLE BUSHING HAVING SHIELDING AND SEALING PROPERTIES

Abstract

The invention relates to a cable bushing with shielding and sealing properties for connection to a wall having an opening, said cable bushing comprising a sealing element and a shielding element in which, in turn, one or more cables can be received in perforations and/or penetration zones.

The cable bushing according to the invention is characterized in that the sealing element and the shielding element are formed from an elastomer as a one-piece, at least partially electrically conductive receiving element for the at least one cable.

Claims

1. Cable bushing with shielding and sealing properties for connection to a wall having an opening, said cable bushing comprising a sealing element and a shielding element in which, in turn, one or more cables can be received in perforations and/or penetration zones, wherein the sealing element and the shielding element are formed from an elastomer as a one-piece, at least partially electrically conductive receiving element for the at least one cable.

2. Cable bushing according to claim 1, wherein the one-piece, at least partially electrically conductive receiving element is formed from an elastomer which has an electrical conductivity due to additives.

3. Cable bushing according to claim 1, wherein the one-piece, at least partially electrically conductive receiving element is formed from an elastomer which has an electrically conductive surface coating.

4. Cable bushing according to claim 1, wherein the perforations or penetration zones are designed to bear against the outer insulation or the cable sheath of the cable.

5. Cable bushing according to claim 1, wherein the perforations or penetration zones have two different internal diameters which are designed to bear against the outer insulation or the cable sheath of the cable on the one hand and to bear against a stripped portion of the cable, in which the electrically conductive cable shield is exposed, on the other hand.

6. Cable bushing according to claim 1, wherein each of the perforations or each of the penetration zones is formed by two regions of the receiving element which are spaced apart in the axial direction of the cable, with a cavity located therebetween.

7. Cable bushing according to claim 1, wherein the receiving element is accommodated in an electrically conductive screw-in housing or frame which is designed to be electrically conductively connected to the wall around the opening.

8. Cable bushing according to claim 7, wherein the electrically conductive frame or the electrically conductive screw-in housing is formed from an electrically conductive plastic.

9. Cable bushing according to claim 1, wherein the receiving element has one or more perforations which are connected to the outer circumference of the receiving element via one or more slits.

10. Cable bushing according to claim 1, wherein the receiving element has a circumferential groove along its outer circumference.

11. Cable bushing according to claim 2, wherein the perforations or penetration zones are designed to bear against the outer insulation or the cable sheath of the cable.

12. Cable bushing according to claim 3, wherein the perforations or penetration zones are designed to bear against the outer insulation or the cable sheath of the cable.

13. Cable bushing according to claim 2, wherein the perforations or penetration zones have two different internal diameters which are designed to bear against the outer insulation or the cable sheath of the cable on the one hand and to bear against a stripped portion of the cable , in which the electrically conductive cable shield is exposed, on the other hand.

14. Cable bushing according to claim 3, wherein the perforations or penetration zones have two different internal diameters which are designed to bear against the outer insulation or the cable sheath of the cable on the one hand and to bear against a stripped portion of the cable, in which the electrically conductive cable shield is exposed, on the other hand.

15. Cable bushing according to claim 2, wherein each of the perforations or each of the penetration zones is formed by two regions of the receiving element which are spaced apart in the axial direction of the cable, with a cavity located therebetween.

16. Cable bushing according to claim 3, wherein each of the perforations or each of the penetration zones is formed by two regions of the receiving element which are spaced apart in the axial direction of the cable, with a cavity located therebetween.

17. Cable bushing according to claim 4, wherein each of the perforations or each of the penetration zones is formed by two regions of the receiving element which are spaced apart in the axial direction of the cable, with a cavity located therebetween.

18. Cable bushing according to claim 5, wherein each of the perforations or each of the penetration zones is formed by two regions of the receiving element which are spaced apart in the axial direction of the cable, with a cavity located therebetween.

19. Cable bushing according to claim 2, wherein the receiving element is accommodated in an electrically conductive screw-in housing or frame which is designed to be electrically conductively connected to the wall around the opening.

20. Cable bushing according to claim 3, wherein the receiving element is accommodated in an electrically conductive screw-in housing or frame which is designed to be electrically conductively connected to the wall around the opening.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In the figures:

[0021] FIG. 1 shows a conventional EMC cable bushing according to the prior art;

[0022] FIG. 2 shows a cable bushing according to the disclosure in a first possible embodiment;

[0023] FIG. 3 shows a cable bushing according to the disclosure in a second possible embodiment;

[0024] FIG. 4 shows a cable bushing according to the disclosure in a third possible embodiment; and

[0025] FIG. 5 shows a cable bushing according to the disclosure in a fourth possible embodiment;

[0026] FIG. 6 shows a cable bushing according to the disclosure in a fifth possible embodiment.

DETAILED DESCRIPTION

[0027] The diagram of FIG. 1 shows a conventional cable bushing, which is also referred to as an EMC cable gland, according to the prior art. This has a screw-in housing 1 which consists for example of a double nipple 7 and a pressure screw 8. Inserted between the double nipple 7 and the pressure screw 8 is an electrically conductive intermediate piece having spring leaves 10 which are provided for contacting an electrically conductive cable shield 4 of a cable 13. As can be seen at the left-hand end of the diagram in FIG. 1, the cable 13 itself may consist of one or more conductive wires 11 which are surrounded by an inner insulation 12. The latter is in turn surrounded by the electrically conductive cable shield 4, which in turn is surrounded by a cable sheath 3 as outer insulation. Besides this electrical contacting of the cable shield 4 for shielding purposes, a sealing element 14 is provided inside the pressure screw 8 for sealing the structure against dust/water and for achieving strain relief for the cable 13. The entire structure can then be inserted in an opening of a wall 19, for example the wall 19 of an electrically conductive housing or switch cabinet, in a manner sealed by way of the double nipple 7, for example by way of the indicated O-ring seal 16, and clampingly screwed to the wall 19 by way of a screw 20 in the region of the double nipple 7. The contacting via the spring leaves 10 enables only a conductive shield, but the latter is interrupted multiple times around the circumference so that electromagnetic waves can penetrate at these locations.

[0028] The simplest embodiment variant of the disclosure is shown in the diagram of FIG. 2. A one-piece and integral receiving element 2 performs the function of sealing, strain relief and shielding. The receiving element 2 is at least partially electrically conductive and is formed from elastomer and receives, in a perforation 17, the cable 13 along its cable sheath 3, that is to say the outer insulation. For installation purposes, the receiving element 2 itself is elastically deformed in the opening of the wall 19 of the switch cabinet and, once it has returned to its initial shape, then receives the wall 19 in a circumferential groove 9.

[0029] FIG. 3 shows a comparable structure. The only difference here is that the receiving element 2 is accommodated in an illustrated screw-in housing 1, similar to the structure according to the prior art in FIG. 1.

[0030] FIG. 4 shows a further comparable structure. The only difference here is that the receiving element 2 is accommodated in a frame 6. If the receiving element covers at least approximately the entire opening, the frame 6 need not necessarily be electrically conductive, but it may be.

[0031] In this simplest variant of the cable bushing shown in FIGS. 2 to 4, there is no electrical contacting of the cable shield 4 in the cable 3, said cable shield 4 not being shown here but nevertheless being present. Instead, it is a case of relying on the fact that electrically conductive materials are present over the entire cross-section, with the exception of the annular gaps of the cable insulations. These annular gaps are typically so small that shielding up to around 10 GHz is possible without any problem. Only for interference already located on the electrically conductive cable shield 4 may shielding not be achieved, but rather said interference will run through the cable bushing in this embodiment variant shown in FIGS. 2 to 4 into the illustrated interior 5 of the switch cabinet.

[0032] The diagram of FIG. 5 shows an alternative embodiment. Instead of the screw-in housing 1 or the groove 9 as the connection between the receiving element 2 and the wall 19, a frame 6 is again provided here in a manner analogous to the diagram in FIG. 4, which frame is connected to the wall, for example by screwing, but should now be preferably electrically conductive. Here, the perforation 17 in the receiving element 2 has a first diameter 171 and a second diameter 172. The two diameters 171 and 172 of the perforation 17 are adapted to one another in such a way that, in the region of the diameter 171, the receiving element 2 bears against the cable sheath 3 of the cable 13 in a manner sealed against water and dust. On the other hand, in the region of the diameter 172, which is slightly smaller, typically in the order of magnitude of around 2 mm relative to the diameter, the receiving element bears against the cable shield 4 of the cable 13, which is again exposed here in a manner analogous to the diagram in FIG. 1. In addition to the shielding of field-bound electromagnetic waves, which attempt to penetrate through the wall 19 via the opening which is closed by the receiving element 2 in the frame 6, the interference already located on the cable shield 4 can thus also be dissipated. The shielding is therefore improved. The strain relief and the sealing against water and dust can be achieved via a higher contact pressure. At the same time, the reliable contacting of the cable shield 4 can also be achieved, so that the interior 5 of a switch cabinet for example is ideally protected by way of the receiving element 2.

[0033] Given sufficient elasticity of the elastomer of the receiving element 2, it is also conceivable to configure the perforation 17 with a constant diameter during manufacture, so that the two different diameters for bearing against the cable sheath 3 on the one hand and the cable shield 4 on the other hand are achieved as a result of the elasticity of the elastomer only at the time of insertion or after insertion of the cable 13 into the receiving element 2.

[0034] The diagram of FIG. 6 shows a further variant. In a manner analogous to the embodiment shown in FIG. 2, the wall 19 around the opening is connected to the receiving element 2 with a form fit. This shows in the axial direction of the cable 13 a perforation 17 having a first diameter 171 which surrounds the cable sheath 3 sealingly and with strain relief. Said perforation 17 is followed by a type of cavity 18 or a correspondingly larger diameter of the perforation. This is then followed by a further part of the perforation 17 having a smaller diameter 172 in the manner of a membrane. Upon insertion of the cable 13, said membrane closes around a stripped part of the cable 13, in which the electrically conductive cable shield 4 is exposed, and thus contacts the receiving element 2 with the latter. As a result, the conductive wall 19 of the switch cabinet is also contacted with the cable shield 4 via the receiving element 2. This provides ideal sealing and shielding while allowing very easy installation. The structure can in particular be used to shield the interior (denoted 5 in the diagrams of the figures) of a switch cabinet (not shown) on the one hand and to reliably seal it against dust and water on the other hand.

[0035] According to one highly advantageous development of the concept according to the disclosure, the at least partially electrically conductive elastomer of the receiving element may consist of an elastomer which is conductive per se or of an elastomer which contains conductive additives. A sufficient conductivity for the electromagnetic shielding is achieved as a result.

[0036] According to an alternative highly advantageous development of the cable bushing according to the disclosure, it may also be provided that the at least partially electrically conductive elastomer of the receiving element is produced from an electrically non-conductive elastomer which has an electrically conductive surface coating. Of course, the structures could also be combined, so that an electrically conductive elastomer could additionally carry a conductive surface coating.

[0037] The frame 6 and the screw-in housing 1 may also be made of an electrically conductive plastic or may be provided with an electrically conductive surface coating in a manner analogous to the receiving element. Alternatively, of course, structures of the screw-in housing and of the frame which are made of previously customary materials, for example metals such as in particular nickel-plated brass, are also conceivable.

[0038] The different variants for connecting the wall 19 to the receiving element 2, via the groove 9, the frame 6 or the screw-in housing 1, can of course be combined at will with any variant of the receiving element 2 in FIGS. 2 to 6.