Device for introducing a cable into a room

The invention relates to an apparatus for carrying a cable,

The invention relates to an apparatus according to the preamble of claim1. Such apparatuses are also referred to as “cable bushing”, for example in DE 103 56 386 B3.

The mentioned cables are, for example, introduced into a control cabinet. The cable comprises at least one conductor, generally in the form of a copper wire or a plurality of fine copper wires, a shield braid surrounding the conductor and finally an electrically non-conductive protective coat surrounding the shield braid. In the state of the art, the cable is usually enclosed by a housing in the form of a cable gland. The housing consists of an electrically conductive metal, for example of nickel-plated brass. The gland is inserted into or attached to a bore of a wall, for example the wall of a control cabinet. At the end of the cable which is inside the control cabinet in the assembled state, a switch or a plug or any other electrical device is connected to the conductor of the cable in an electrically conductive manner.

The apparatus as a whole fulfills different functions: It comprises a sealing ring which prevents the penetration of moisture or dust into the control cabinet. The shield braid serves as an electromagnetic shield. It is conductively connected to the cable gland via spring leaves and the conductive cable gland in turn is connected to the electrically conductive wall via which grounding takes place.

One disadvantage of this embodiment, among other things, is that the voids between the spring leaves are not covered. This means that the conductive protective shield is interrupted in these regions. Electromagnetic waves can penetrate these regions, which is a disadvantage.

One further disadvantage is that the diameter of the cable grand is large and that the opening of the control cabinet wall therefore must be sufficiently large. It is therefore not possible to introduce a ready-for-use, i.e. assembled component with a housing and a plug.

Further, the cable gland contains a strain relief.

From AT 339 404, a cable bushing is known wherein the cable is received in an electrically non-conductive material. A metallic pin is pressed through this material and penetrates the outer cable sheath and creates a contact with a shield braid. The pin is then pressed into a conical receptacle in such a way that it is also electrically connected to the housing. The assembly is very complex and installation is time-consuming. Disassembly is only possible to a certain extent. Further, due to the pressed-in pin, there is a high risk that an area of the shield braid is penetrated which has no wires or which cannot guarantee an overly good attachment between the individual wires and the pin, so that there is a risk of the shield being of bad quality.

Concerning the further state of the art, reference is also made to DE 77 21 692 U1.

With regard to the industrial interconnection of components, requirements are increasing. These concern the electromagnetic compatibility (EMC) of cable introduction equipment as well as the allowed seal against moisture and dust, strain relief and finally production and assembly.

The invention is therefore based on the task to fulfill the mentioned requirements in a better way than the apparatuses according to the state of the art. This task is solved with the features of claim1.

The main idea of the invention consists of the following:

The sleeve consists of at least partially electrically conductive material, for example of an elastomer.

The housing consists at least partially of electrically conductive material.

The sleeve is connected to the housing in a conductive manner.

The hinged sleeve encloses the shield braid on a longitudinal section on which the protective coat had been removed.

The discharge of electromagnetic disruptive flows therewith goes from the shield braid via the electrically conductive sleeve, the electrically conductive housing, the wall of the control cabinet and thus forms a grounding.

The resulting advantages can be summarized as follows:

By using an electrically conductive sleeve, any connecting element which establishes an electrically conductive connection between the shield braid and the housing is omitted.

The electrically conductive sleeve directly abuts the housing. Thus, any void within the housing is avoided. This also means that the conductive protective shield is not interrupted, so that electromagnetic waves are not able to penetrate these regions.

The radial dimension of the apparatus is minimized by the electrically conductive sleeve. The apparatus can thus also be guided through relatively narrow openings in a control cabinet wall.

By using an electrically conductive sleeve and by its direct contacting abutment on the housing, conductive elements between these two, namely metal springs or the like, are spared, which saves the costs for providing such elements as well as for their assembly.

The complete apparatus including the cable, sleeves, housing and, if applicable, a plug, can be introduced into an opening of a wall, for example of a control cabinet, in its ready-for-use state.

According to a very advantageous development of the idea, a second, further sleeve may be provided as a seal against the penetration of moisture and dust and with the additional function of a strain relief.

In the known embodiment shown inFIG. 1, a cable1can be seen. It comprises a multi-wired conductor1.1. The conductor1.1is coated with an internal protective coat1.2. The protective coat is coated with a shield braid1.3. The shield braid1.3in turn is coated with an outer protective coat1.4.

The cable1is surrounded by a housing2. The housing comprises a threaded sleeve2.1with an external thread and a screw cap2.2with an internal thread. The housing further comprises a seal3and a strain relief4.

The outer protective coat1.4is removed on an axial part of the cable1, so that the shield braid1.3is exposed. A number of metal springs5creates an electrically conductive connection between the shield braid1.3and the housing2. The housing2is electrically connected to a wall of a control cabinet which is not shown herein. A discharge of electromagnetic disruptive flows takes place from the shield braid1.3to the electrically conductive wall of the control cabinet via the springs5.

FIGS. 2 and 3show an embodiment according to the invention. Here, there is also a cable1which has the same structure as the cable1according toFIG. 1. Thus, it has in turn a multi-wired conductor1.1surrounded by an internal protective coat1.2which is surrounded by a shield braid1.3, which is in turn surrounded by an outer protective coat1.4, and a plug11.

Cable1is inserted into two hinged sleeves, namely a sealing sleeve6for the insulation from dust and water, and an electrically conductive sleeve7. Both can be made of an elastomer. The elastomer of the sleeve7is electrically conductive. It may have filler materials and/or a coating suitable for this purpose.

In the collapsed state, the sleeve7and the sealing sleeve6enclose the cable1. In the region of the sleeve7, the outer protective coat1.4of the cable1is removed. The sleeve7surrounds the shield braid1.3and abuts it in a contacting manner. Due to the electrical conductivity of the sleeve7, an electrically conductive connection is established between the shield braid1.3and the sleeve7. The sealing sleeve6encloses the cable in the region of the outer cable coat1.4and thus provides for a very good seal.

Further, a two-part housing2can be seen. It consists of two parts2.1and2.2. After closing the sleeve7and the sealing sleeve6, the two housing parts2.1and2.2are put over the sleeve7and the sealing sleeve6and connected. They are fixed to each other by a lock. After connecting the housing parts2.1and2.2, they form a thread2.3. For the installation on a wall9of a control cabinet, the part of the housing2which is provided with the thread2.3is introduced through an opening in the wall9and screwed to a threaded ring8. The threaded ring8is assembled from two ring halves8.1and8.2.

The coat area of at least the electrically conductive sleeve7completely abuts the jamb of the bore of the housing2. This also applies to the electrically conductive sleeve7. This means that there is no gap and thus no cavity between the electrically conductive sleeve7and the housing2. This can also apply to the sealing sleeve6.

The electrically conductive housing2thus also establishes an electrically conductive connection between the shield braid1.3, the sleeve7, the housing2and the wall9which is also electrically conductive. This constitutes a reliable shield.

The view of the assembly according toFIG. 3shown inFIGS. 4, 5 and 6without the inserted cable1again show the housing2and its two housing parts2.1and2.2and the electrically conductive sleeve7in the representation ofFIG. 4and the sealing sleeve6in the representation ofFIG. 6. As can be seen, the two parts of the housing are clipped to one another, which is particularly noticeable in the representations ofFIGS. 3 and 5.FIGS. 4 and 6also show the slot10in the respective hinged sealing sleeve6and the sleeve7very clearly.

In the representation ofFIG. 7, a section of the assembly analogous to the representation inFIG. 3can be seen. The only difference is that the electrically conductive sleeve7and the sealing sleeve6are not arranged in a spaced manner anymore, such as in the representation ofFIG. 3, but, in this case, abut each other in a contacting manner, so that this results in a correspondingly compact assembly with a good seal.

In a cross section of the representation ofFIG. 8, an assembly which shows two electrically conductive sleeves7and two sealing sleeves6can be seen. This assembly is also formed for receiving more than one cable1. The representation ofFIG. 8shows the possibility of receiving two cables1. As can be seen from the followingFIGS. 9, 10and the three-dimensional view inFIG. 11, it is really intended to receive four cables1in four sealing sleeves6and four electrically conductive sleeves7. Alternatively, this assembly would theoretically also allow the introduction of a respective individual very large electrically conductive sleeve7and sealing sleeve6for receiving one individual cable with a very large diameter. The assembly according toFIG. 8is, as already mentioned, shown in a first variant inFIGS. 9, 10 and 11. In this variant, the two halves2.1and2.2of the housing2are screwed together. An analogous representation can be found inFIGS. 12, 13 and 14which show the assembly which is shown in cross-section inFIG. 8again, wherein, contrary to the screwed embodiment of the housing halves2.1and2.2, the housing halves2.1and2.2here are in turn clipped to one another, analogous to the representations inFIGS. 2 and 3.

It is useful to connect the electrically conductive sleeve7to the sealing sleeve6for protection against dust and moisture in series, so that the respective cable1or the cables1carry of the sealing sleeve6and the sleeve7in an axially shifted manner.

However, it is also possible to provide embodiments with only one single sleeve7per cable1, namely an electrically conductive sleeve7. Such sleeve is represented inFIG. 15analogous to the above-mentioned Figures. The sleeve7takes over the function of the electrical contact of the shield braid1.3and, up to a certain degree, sealing and strain relief functions as well. However, as the shield braid1.3itself is not sealed and possibly mechanically unstable as well, minor limitations must be accepted. However, depending on the application purpose, this can be possible without any problems.