Shielding device and arrangement with a shielding device

Abstract

Shielding device (1) for passing at least one electrical conductor (3) through a wall of a metal housing (2) or a metal-coated housing, wherein the shielding device (1) has a support (10) made of an insulator which is provided on at least one side with a metal coating (11) and has at least one through-hole for passing the at least one conductor (3), characterized in that the metal coating (11) has a distance (b) from the edge of the through-hole.

Description

The invention relates to a shielding device for passing at least one electrical conductor through a wall of a metal housing or a metal-coated housing. The invention further relates to an arrangement with such a shielding device.It is known from the prior art for improving the electromagnetic compatibility (EV) of electrical appliances to use housings made of metal or housings made of other materials which are coated with metal. These housings then form a Faraday cage which protects the interior of the housing from external electromagnetic interference and the environment of the housing from electromagnetic interference from the interior of the housing. Electromagnetic waves are shielded by the housing.Weak points in the shielding regularly form apertures in the housings, which must be provided for feed lines, plug connectors, displays or the like. While displays can still be placed on the outside of the housing, so that a breakthrough in the housing wall can be avoided, it is not possible to dispense with feed lines, whether they be feed lines for energy supply or feed lines for data transmission.Similar arrangements are known from DE 198 16 230 A1 and from U.S. Pat. No. 5,557,074 A.The object of the invention was therefore to improve the electromagnetic compatibility by improving the shielding of feedthroughs of electrical conductors by a housing wall.This object is achieved by a shielding device according to claim 1. The shielding device has the one carrier made of an insulator, which is provided with a metal coating at least on one side and has at least one through hole for the passage of the at least one conductor. Here, the metal coating has a distance from the edge of the through hole, so that the distance of the metal coating from the conductor is greater than the distance of the edge of the through hole from the conductor.The distance is preferably not more than 1 mm. The distance is particularly preferably less than 1 mm. The carrier may be a plate. Preferably, the carrier is adapted to the external shape of the metal housing or housing in the region in which the conductor is passed through the wall of the housing.When using the shielding device, the conductor is passed through the through hole in the carrier of the shielding device according to the invention. The conductor is also passed through a hole in the metal housing or in the housing with the metal layer. At the same time, the metal coating of the shielding device is applied to the metal housing or the housing facing the metal housing or the metal layer of the housing, so that an electrical contact is produced between the metal of the shielding and the metal of the metal housing or the metal layer of the housing. The metal layer of the shielding device thus continues the Faraday cage formed by the metal of the metal housing or housing and interrupted in the region of the hole for the passage of the conductor.The cross section of the through hole and the cross section of the conductor are matched to one another such that there is a clearance fit between the conductor and the shielding device. This is expedient because dimensional tolerances can be compensated thereby. It is also expedient, however, to keep the play between the conductor and the shielding device as small as possible in order to reduce as far as possible the possibility of electromagnetic waves passing through the gap. On the other hand, care must be taken that when the shield support and the conductor come into contact, at least the metal coating of the shielding device does not come into contact with the conductor, because otherwise ground faults of the conductor could follow via the grounded metal housing or the grounded housing.The metal coating of the shielding device must come directly into electrical contact with the metal of the housing. It is not protected by a lacquer or other insulating material.The object is also achieved by an arrangement according to claim 3. The arrangement comprises a metal housing or a housing having a metal layer, an electrical conductor which is led through a wall of the metal housing or of the housing, and a shielding device according to the invention. In such an arrangement, the conductor is passed through the through hole of the carrier of the shield device, through the metal coating and the hole in the housing, and the coating of the shield device is applied to the wall of the metal housing or to the metal layer of the wall of the housing. Thus, the metal layer of the shielding device is in electrical contact with the metallic layer of the housing.In the arrangement according to the invention, as already explained in connection with the use of the shielding device, a gap for compensating dimensional tolerances can be provided between the edge of the through-hole of the carrier and the electrical conductor.The wall of the metal housing or housing may have a recess into which the shielding device is inserted. The recess can be a depression of the outer surface of the metal housing or of the housing, into which depression the shielding device fits flush with the surface of the metal housing or of the housing surrounding the depression.An arrangement according to the invention can have a plastic component which accommodates the conductor outside the housing or the metal housing. The plastic component can be injection molded around the conductor. The plastic component and the at least one conductor can form a plug.The plastic component and the housing have connecting structures via which the plastic component and the housing are connected to one another, optionally using connecting means. The connection could be a plug-and-socket connection. It is likewise possible for the plastic component and the housing to be connected to one another by screws, adhesive bonding or other means.The arrangement can have a plurality of electrical conductors. The carrier can then have a number of through-holes corresponding to the number of conductors, each conductor being led through a through-hole. The conductors can be passed together through at least one hole in the wall of the metal housing or of the housing.The conductor of an arrangement according to the invention can be connected to a circuit, preferably to a filter circuit, via a preferably resilient contact element. The circuit may include capacitors, for example. The circuit may be arranged on the carrier. It is possible for it to be in conductive contact with the metal layer on the carrier.The invention is explained in more detail below with reference to the accompanying drawings. The following shows: FIG. 1 shows a sectional illustration, not to scale, of an arrangement according to the invention with a shielding device according to the invention.The arrangement according to the invention shown comprises a shielding device 1, a metal housing 2, a conductor 3 and a plastic component 4.The metal housing 2, of which only a part of a wall is shown, houses an electronic assembly which generates electromagnetic radiation. In order to improve the electromagnetic compatibility of the assembly, that is to say to shield the environment from the electromagnetic radiation, the housing 2 is made of metal and forms a Faraday cage. This Faraday cage is interrupted at some locations, namely where electrical conductors are routed through the housing 2 to the assembly. One of these conductors is the conductor 3 shown in FIG. 1, the conductor 3 being in the example a solid copper rod, a so-called busbar.The conductor 3 is fixedly arranged in the plastic component 4. The plastic of the plastic component 4 is injection molded around the conductor 3.In the region of the hole through which the conductor 3 is guided through the wall of the housing 2, the shielding device 1 is arranged between the housing 2 and the plastic component 4.The shielding device 1 has a carrier 10. The carrier 10 is made of an insulator. The carrier material can be a material as is usually used for circuit carriers, for example FR2 to FR5, CEM1, CEM5 et al., as listed in the article "Schaltschenbalten" in the German Wikipedia.In addition to the carrier 10, the shielding device 1 also has a metal coating 11 which is applied on one side to the carrier 10. The metal coating 11 completely covers one side of the support 10 with an exception yet to be explained.The shielding device 1 has a through hole through which the conductor 3 is passed. Between the carrier 10 and the conductor 3 there is provided a clearance a which serves to compensate for dimensional tolerances. A play a of less than 1 mm is sufficient for this purpose. In principle, the ladder 3 could also be guided through the carrier 10 without play a.In any case, a distance a+b must remain between the metal coating 11 and the conductor 3, so that electrical contact between the metal coating 11 and the conductor 3 is ruled out. This is achieved in that no metal coating 11 is provided on the otherwise coated side of the carrier 10 circumferentially around the through hole in the carrier 10 in a narrow band of width b. A distance a+b between the conductor 3 and the metal coating of less than 1 mm is sufficient.The shielding device 1 is placed with the side of the metal coating 11 on the metal housing 2 so that an electrical contact is established between the housing 2 and the metal coating.The interruption of the Faraday cage formed by the housing 2 formed by the hole in the housing 2 for passing through the conductor 3 is reduced by the shielding device 1. Only the small gap between the metal coating 11 and the electrical conductor 3 can be penetrated by electromagnetic radiation.On the side of the carrier 10 facing away from the housing 2, a circuit with components, e.g. capacitors 12, is provided. This circuit serves for filtering disturbances, in particular power-bound disturbances. For this purpose, the circuit is electrically conductively connected to the metal coating 11, for example by a plated-through hole (not illustrated). On the other hand, the circuit is conductively connected to the conductor 3 via a preferably resilient contact element 13.List of reference characters1 Shielding device 10 Support 11 Metal coating 2 Metal housing 3 Conductor 4 Plastic part

Claims

Shielding device (1) for passing at least one electrical conductor (3) through a wall of a metal housing (2) or a metal-coated housing, wherein the shielding device (1) has a carrier (10) made of an insulator which is provided at least on one side with a metal coating (11) and has at least one through-hole for passing the at least one conductor (3), characterized in that the metal coating (11) has a distance (b) from the edge of the through-hole.Shielding device (1) according to claim 1, characterised in that the carrier (10) is a plate.Arrangement comprising a metal housing (2) or a housing having a metal layer, an electrical conductor (3) which is guided through a hole of a wall of the metal housing (2) or of the housing, and a shielding device (1), characterized in that the shielding device (1) is formed according to one of Claims 1 or 2, in that the conductor (3) is guided through the through-hole of the carrier (10) of the shielding device (1) and through the hole of the wall, and in that the metal coating (11) of the shielding device (1) bears against the wall of the metal housing (2) or against the metal layer of the wall of the housing and is in electrical contact therewith.Arrangement according to claim 3, characterised in that the wall of the metal housing (2) or of the housing has a recess (20) into which the shielding device (1) is inserted.Arrangement according to one of Claims 3 or 4, characterized in that the arrangement has a plastics component (4) which accommodates the conductor (3) outside the housing or the metal housing (2).Arrangement according to Claim 5, characterized in that the plastics component (4) is injection-moulded around the conductor (3).Arrangement according to Claim 5 or 6, characterized in that the plastics component (4) and the housing or metal housing (2) have connecting structures via which the plastics component (4) and the housing or metal housing (2) are connected to one another, optionally using connecting means.Arrangement according to one of Claims 3 to 7, characterized in that the arrangement has a plurality of electrical conductors (3) and the carrier (10) has a number of through-holes corresponding to the number of conductors (3), each conductor (3) being led through a through-hole, and in that the conductors (3) are led jointly through at least one hole in the wall of the metal housing (2) or of the housing.Arrangement according to one of Claims 3 to 8, characterized in that the arrangement has an electrical circuit, preferably a filter circuit, which is arranged on the carrier (10) and is electrically conductively connected on the one hand to the metal coating (11) of the carrier and on the other hand to the conductor or conductors (3).

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