Abstract:
The invention relates to a flexible sealing element sealingly attached to a cable intended for connection to attachment means on e.g. the roof of a base station cabinet. When attaching the cable the front end of the sealing element is retracted to a position uncovering connecting means at the cable end. After attachment the front end is moved back to a position covering the connected cable end.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to an arrangement for sealing a cable transit in a wall of an apparatus room or apparatus casing or a corresponding counterpart. 
       BACKGROUND 
       [0002]    In apparatus rooms for electric equipment there are necessarily a number of inlets and outlets for power supply, signal feeders, antennas or the like. Especially when such houses with equipment are exposed to difficult environment conditions, like weather conditions when the equipment is sited outdoors, in dusty surroundings or otherwise polluted areas, it is important that appropriate sealings are arranged in association with the inlets and outlets. 
         [0003]    In the mobile telecommunication field, like GSM, WCDMA and other modem technologies, radio base stations, RBS, are frequently used and for economic reasons they are often placed outdoors. Such RBS comprises mainly of a cabinet for electronic equipment placed on the ground and an antenna with its mast situated nearby. A feeder cable runs from the-cabinet to the antenna. It is desirable that the feeder is of correct length and as short as possible. For these reasons it is preferred to have the antenna feeder outlet on the roof of the cabinet. 
         [0004]    However if the outlet is placed on top of the cabinet, the quite straight substantially vertical antenna cable functions as a conductor of water in the event of atmospheric precipitation. In this case water may be very liable to run into the inner part of the coupling and possibly also into the apparatus housing, if the seal is not satisfactory. 
       SUMMARY 
       [0005]    The aim of the present invention is to provide an arrangement that will enable a cable transit opening to be placed at any desired location in any desired wall structure of an apparatus room or apparatus casing, including its ceiling or floor, without the chosen location of said opening constituting a risk of water, moisture or minute solid particles penetrating into the room or casing through said opening. 
         [0006]    This aim is achieved in accordance with the present invention by means of a sealing arrangement which is characterised primarily in that it includes a rigid tubular element which is sealingly connected around the full periphery of said opening and which projects out from the outer side of said wall such as to form a passageway that leads into the interior of the room or casing, and in that the arrangement includes a flexible sealing element, which sealingly closes said passageway, wherein the front end of the sealing element has a sleeve-like end portion which can be fitted onto the tubular element and which enables the sealing element to be fitted in tight abutment with said tubular element around its full periphery. 
         [0007]    According to the present invention, the sealing element may be adapted to sealingly close said passageway by virtue of its co-action with an external electric cable intended for connection to electrical equipment installed in the apparatus room or apparatus casing. 
         [0008]    The sealing element is preferably comprised of a gaiter which has, at its rear end, a sleeve-like part by means of which the gaiter can be brought into sealing abutment with the outer barrel surface of a part of said cable, around the full circumference of the cable. 
         [0009]    This stocking-like gaiter element will conveniently include a generally cylindrical front portion and a generally cylindrical rear portion preferably of smaller diameter than the front portion. An elongate connecting part is situated between said two portions. The intermediate connecting portion preferably has a generally conical form. 
         [0010]    The connecting portion of the gaiter element is capable of supporting the front part of the element stably in two different position in relation to the rear part of said element, namely in a forwardly displaced position in which the front portion is situated at a considerable axial distance from the rear portion, and a rearwardly withdrawn position in which the front portion is situated close to the rear portion at least partially overlapping said portion. 
         [0011]    When the connecting portion has a generally conical shape, as before mentioned, the function of the invention can be improved by reducing the material thickness of the connecting portion in a direction from its rear end towards its front end, and by joining said connecting portion with said front portion by means of a narrow or thin flange that projects radially outwards therefrom. 
         [0012]    In order to enhance the grip of the rear part of the sealing element around a cable and to achieve highly reliable sealing between said rear part and the cable in the absence of any further means, said part of the stocking-like element may conveniently include a plurality of internal, peripherally extending ridges that are mutually separated by peripherally extending grooves. Alternatively, this part of the sealing element may be crimped around the cable, glued or firmly clamped thereto with the aid of a clamping ring or technically equivalent means, for the same purpose. A combination of said tightening means could also be used. 
         [0013]    The sealing element conveniently consists of an elastic or flexible material. A silicone rubber can be mentioned as an appropriate material in this regard. 
     
    
     
       SHORT DESCRIPTION OF THE FIGURES 
         [0014]      FIG. 1  is a cross-sectional view of one exemplifying embodiment of an inventive sealing arrangement shown in a cable transit opening in a wall portion of an apparatus room, and also shows an outer cable connected to an inner cable in said transit opening. 
           [0015]      FIG. 2  is a corresponding view illustrating the outer cable in a spaced relationship with the inner cable. 
           [0016]      FIG. 3  is a cross-sectional view of said sealing element shown in larger scale; and 
           [0017]      FIG. 4  is a cross-sectional view of the cable transit corresponding to the view of  FIG. 1  and illustrating a protection cap for the cable transit opening when not in use. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0018]    The invention will now be described in more detail with reference to the drawings. 
         [0019]    The reference numeral  10  in  FIG. 1  identifies a steel-plate outer wall of an apparatus room or shelter, while reference numeral  11  identifies a cable transit opening provided in the wall. 
         [0020]    A steel element  12  is rigidly mounted in the opening. The element  12  includes a main part  13  in the form of a tubular member of circular cross-section that extends out from the outer side of said wall  10  and that delimits a passageway  15  leading to the space  14  situated inwardly of the wall  10 . 
         [0021]    The inner end of the element  12  includes a radially and outwardly projecting ring-shaped flange  16  which abuts the inner side of the wall  10 . The element  12  is connected sealingly to the wall  10  around the full circumference of the opening  11 , by means of a weld  17 . The element  12  is provided at its outer end with a ring-shaped flange  18  which projects radially inwards in a direction from the main part  13 . This flange functions as an attachment for a contact device  20  fitted to one end of a cable  19  situated in the space  14  inside the apparatus room. 
         [0022]    Reference numeral  21  identifies a contact device fitted to one end of an external cable  22 , said contact devices  20 ,  21  being joined together such as to mutually connect the cables  19  and  22 . 
         [0023]    The ingress of water, moisture or minute solid particles into the space through the passageway  15  is prevented, by providing a flexible sealing element that sealingly closes said passageway. In the case of the embodiment illustrated, this sealing element is comprised of a gaiter-like element  23  fitted to the cable  22 , said element  23  being shown in more detail in  FIG. 3 . 
         [0024]    The gaiter element  23  includes a cylindrical front portion  24  which forms a front end-portion  25  that can be fitted to the main part  13  of the element  12  and which can be brought into sealing abutment with said main part  13  around its full circumference. The element also includes a cylindrical rear portion  26  that has a reduced diameter in relation to the front portion  24 , and also includes a conical elongate connecting part  27  between said front and rear portions. The cylindrical rear portion  26  forms a rear sleeve-like end-part of the element by means of which the element can be brought into sealing abutment with the outer barrel surface of part of the cable  22 . As a result of the aforedescribed design, the element is able to sealingly close the passageway in co-action with the cable  22 . With the intention of enhancing the mechanical strength of the rear part  26  of the gaiter element on the cable  22  and also in providing an extremely reliable seal between said part and the cable, the rear part  26  can be provided with a plurality of inner, peripherally extending ridges  36  and peripherally extending grooves  37  located therebetween. 
         [0025]    In order to facilitate mutual connection of the two contact devices  20  and  21 , the aforesaid connecting part  27  is adapted to support the front part  24  stably in two different positions in relation to the rear part  26 . These two positions consist, on one hand, of a forwardly displaced position shown in  FIG. 1 , in which the leading part  24  is located at a relatively large axial distance from the rearward part  26 , said distance being determined by the maximal length of the connecting part  27 , and projects out in front of the contact device  21 , wherein, on the other hand the second position is a withdrawn position shown in  FIG. 2  in which the leading front part  24  is situated close to the rearward part  26  and partially overlaps the same whilst exposing the connection device  21  at the same time thus facilitating the connection of the cable to the counterpart. 
         [0026]    In order to achieve the aforedescribed function of the connecting part  27 , said part has preferably been given a material thickness that decreases from its rear end towards its front end. It has also been connected to the front part  24  with the aid of a thin flange  28  that projects out from said connecting part in a generally radial direction. 
         [0027]    The front end portion  25  of the sealing element  23  that can be fitted to the main part  13  of the counterpart element  12  includes an inner ring-shaped bead  29  which is intended for engagement with an outer ring-shaped groove  30  in the part  13 . This will provide a visual indication of the fact that the end portion  25  has been placed in its intended position on the part  13 . The bead  29  also enables reinforced attachment of the end portion  25  to be achieved on the part  13  when fitted. However, a clamping ring  31 , for instance a hose clamp, may be applied to the end part  25  for further reinforcement of both the attachment of the end part to the part  13  and also reinforcement of the seal between said two elements. 
         [0028]      FIG. 4  illustrates a sealing cap  32  intended for use as a sealing connection of a cable transit, where no outer cable is connected at this time. 
         [0029]    The cap  32  includes a front end portion  33  which can be fitted to the part  13  and which is designed similarly to the end portion of the sealing element  23 , whereas the rear end of the cap  32  includes an end wall  34  that outwardly closes the portion  33 . The reference numeral  35  identifies a rigid hat which is fitted inwardly of the cap  32  and which functions to provide extra protection to the electric contact device  20  that is fitted inwardly of the cap  32 , and which also functions to provide extra projection to the electric contact device  20  against damage from external forces. The cap  32  and the gaiter-like element  23  may both be produced conveniently from silicone rubber. It will be understood, however, that other weather-resistant materials that have good elastic or flexible properties within a large temperature range may also be used. 
         [0030]    When applying the invention for sealingly mounting of e.g. an antenna feeder cable on the roof of an RBS cabinet, the process is started with the removal of the protection cap  32 , shown in  FIG. 4 . A preferably fixed length of an antenna cable with associated connecting means  21  and a gaiter  23  in its retracted position—as in FIG.  2 —is connected to inlet connecting means  20  of the RBS cabinet. The rear part of the gaiter could be more or less fixed to the feeder already on delivery using any of the aforementioned tightening means. The front part of the gaiter element  23  is then moved to the position shown in  FIG. 1 . If enhanced sealing properties are desirable a clamping ring  31  is then used to tighten the joint between the forward end  24  of the gaiter and the connecting parts of the cabinet. 
         [0031]    The invention has so far been illustrated in the figures with a side mounted inlet for antenna feeders. It is however obvious that the same construction is suitable for other positions of the mountings in the bottom or top of housings for electric equipment. Thereby, for the last mentioned top mounting, the invention solves the raining water problems with the cable on its outside acting as a more or less vertical water conductor related to in the Background part of this description. The front part of the connection should in this regard be considered as the lower part of the sealing, while the rear part corresponds to the top part. 
         [0032]    The sealing element is preferably elastic or at least flexible, and made from rubber or some corresponding material, so as to provide an effective seal at both ends and also to enable the sealing element to be displaced between its two positions. But, it is not necessary that the material has elastic properties like the ones rubber has. Any material and any design that enables the described positional change to be achieved are included in the invention. One example in this regard resides in a material that is “foldable” along a periphery of the cylindrical material, so that it can be “rolled” over a movable peripheral “fold” between said two end positions. 
         [0033]    The invention has been conceived primarily with the object of improving the possibility of selectively positioning requisite cable transits in walls of steel-sheet shelters that function to accommodate apparatus connected to mast-mounted antennas in Radio Base Stations for mobile telecommunication systems. The invention, however, can also be applied to other connections of cables apparatus rooms or like counterparts, where the need for proper sealings or protection is necessary. For example, in the case of general joining of a cable in the absence of any connection with an apparatus casing, one part may have a configuration that corresponds generally to the right hand side of  FIG. 1 , whereas the left hand part is not attached to a wall but has a portion that corresponds to the tubular element or pipe socket around which the front part of the sealing element is fitted. Other end to end joining of cables may use the sealing element of the invention on both parts of the joint. Other embodiments are thus conceivable within the scope of the present invention which only limitations are defined in the accompanying claims.