Abstract:
The invention relates to an adapter ( 1 ) for sleeves ( 20 ) with elastomer cable seals ( 28 ), comprising at least one tubular element ( 3 ) and a support element ( 2 ), the support element ( 2 ) comprising means for fastening the support element ( 2 ) to a lower housing part ( 21 ) of a sleeve ( 20 ) and to a method for introducing a fiber-optic cable into a sleeve ( 20 ) using an adapter ( 1 ).

Description:
This application is claims benefit of Serial No. 10 2008 032 753.0, filed 11 Jul. 2008 in Germany and which application is incorporated herein by reference. To the extent appropriate, a claim of priority is made to the above disclosed applications. 
     BACKGROUND 
     The invention relates to an adapter for sleeves with elastomer cable seals and to a method for introducing a fiber-optic cable into such a sleeve. 
     Sleeves for optical-fiber cables have two sealing systems that differ in principle, namely elastomer cable seals in the lower housing part of the sleeve and shrink collars. 
     Recently, new types of optical-fiber cables known as blown-fiber cables have been developed. They comprise a multiplicity of ducts, through which fibers are subsequently blown by means of compressed air. These cables are extremely rigid, so that their direct introduction into the sleeve causes difficulties when the sleeve is subsequently moved. 
     To solve the problem, it is conceivable to strip some of the sheathing from the cable and introduce the ducts directly into the sleeve. The ducts could then be protected outside the sleeve by a flexible tube, which is then brought up to the sleeve. However, this causes problems at the elastomer cable seal. 
     SUMMARY 
     The invention is based on the technical problem of providing an adapter for sleeves with elastomer cable seals and a method for introducing a fiber-optic cable, in particular a blown-fiber cable, into a sleeve, by means of which the aforementioned problems are solved. 
     For this purpose, the adapter for sleeves with elastomer cable seals comprises a tubular element and a support element, the support element comprising means for fastening the support element to a lower housing part of a sleeve. This makes it possible for the sleeve to be subsequently converted in such a way that it allows the use of shrink collars. In this case, the tubular element is sealed by means of the elastomer cable seal, whereas a flexible tube, for example, or a wall bushing is connected in a sealing manner to the tubular element by means of a shrink collar. 
     In principle, the adapter may be formed in one piece or as one part. Preferably, however, the support element and the tubular element are separate components, so that the tubular element can be easily introduced into the sleeve and sealed. The main function of the support element is in this case the mechanical support of the tubular element. 
     In a further preferred embodiment, the tubular element is formed as a metal tube, whereas the support element preferably consists of plastic. Further embodiments in which the tubular element consists of plastic are possible, the plastic not necessarily having to be the plastic of the support element. 
     The support element preferably comprises an annular holding element, which engages around the tubular element. 
     With respect to the method, firstly the tubular element is sealed by means of the elastomer cable seal and the support element is fastened to the lower housing part of the sleeve, the tubular element protruding into the sleeve. The fiber-optic cable to be introduced, in particular a blown-fiber cable, is then partially stripped of its sheathing and the stripped part is threaded through a flexible tube. Subsequently, a shrink collar is pulled over and shrunk on over the cable sheath and the flexible tube. Subsequently, the stripped part of the cable is then led through the tubular element until the flexible tube finishes flush with the tubular element or else is pushed partially onto the tubular element. Finally, a shrink collar is then shrunk on over the tubular element and the flexible tube. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is explained in more detail below on the basis of a preferred exemplary embodiment. In the figures: 
         FIG. 1  shows a perspective side view of an adapter for sleeves with elastomer cable seals, 
         FIG. 2  shows a perspective front view of the adapter according to  FIG. 1 , 
         FIG. 3  shows a perspective front view of a lower housing part of a sleeve with fastened adapters, 
         FIG. 4  shows a perspective rear view of the lower housing part with adapters and 
         FIG. 5  shows a perspective front view of the lower housing part with adapters and optical-fiber cables. 
     
    
    
     DETAILED DESCRIPTION 
     The adapter  1  comprises a support element  2  and a tubular element  3 . The support element  2  comprises an annular holding element  4 , through which the tubular element  3  is inserted. The annular holding element  4  is profiled on its inner surface and has teeth  5 , in order to prevent the tubular element  3  from slipping. Furthermore, the support element  2  has openings, through which fastening screws  6  are inserted in order to screw the support element  2  to a lower housing part of a sleeve. An upper edge  7  of the support element  2  is of a rounded form, in order to match the circular form of the lower housing part. Furthermore, the support element  2  has various reinforcing ribs  8 . The lower edge  9  is shorter than the upper edge  7 , so that the side edges  10  run obliquely away from the upper edge  7  to the lower edge  9 . As a result, the support element  2  is of an almost trapezoidal form. The tubular element  3  is in this case formed as a metal tube, whereas the support element  2  consists of plastic. The tubular element  3  may also be made of plastic. 
     In  FIG. 3 , part of a sleeve  20  with elastomer cable seals is represented, two adapters  1  having been screwed on a lower housing part  21  of the sleeve  20 . The tubular elements  3  in this case protrude into the sleeve  20  and are sealed by the elastomer cable seals, so that no moisture can get into the sleeve. Ducts  22  of a blown-fiber cable (not represented any further) protrude from the left-hand tubular element  3 . Optical fibers can then be routed in these ducts  22 . Inside the sleeve  20 , the ducts  22  are cut to length and terminated with watertight connectors  23 . Then short tubes  24 , known as furcation tubes, are fitted onto these connectors. Further tubes  25  of a smaller diameter are then inserted into the tubes  24  and these tubes of a smaller diameter are led to a fiber management unit  26 . 
     In  FIG. 4 , a rear view of the lower housing part  21  is represented, revealing the two tubular elements  3  of  FIG. 3 . Also shown are the ducts  22 , in the middle of which an inner tube  27  is arranged. This inner tube  27  may also be used in principle for the routing of optical fibers. On the other hand, it is also possible to cut off the inner tube  27  with the stripped part of the cable, so that the flexibility is increased. The elastomer cable seal  28  is then arranged around the tubular elements  3 . 
     The way in which the method provides for the optical-fiber cable, in particular the blown-fiber cable, to be connected is to be explained in more detail on the basis of  FIG. 5 . Firstly, the optical-fiber cable is partially stripped of its sheathing, so that the ducts  22  and the inner tube  27  are exposed. A wall bushing or a flexible tube  29  is pulled over the stripped part and pulled down as far as the remaining cable sheath  30 . Then a first shrink collar  31  is placed over the cable sheath  30  and the flexible tube  29  and shrunk on, so that the transition between the cable sheath  30  and the flexible tube  29  is watertight. By contrast with the representation, the shrink collar in this case actually encompasses the complete circumference. The ducts  22  are subsequently led through the tubular element, until the flexible tube  29  comes up against the tubular element  3 , the flexible tube  29  partially being pulled over the tubular element  3  if this is appropriate. Then the flexible tube  29  and the tubular element  3  are connected to each other in a watertight manner by means of a second shrink collar  32 . 
     It should be noted here that, in the examples represented, a support element  2  in each case only comprises one holding element  4 . However, embodiments in which a support element  2  comprises two or more holding elements  4  are also possible. 
     LIST OF DESIGNATIONS 
     
         
           1  adapter 
           2  support element 
           3  tubular element 
           4  holding element 
           5  teeth 
           6  fastening screws 
           7  upper edge 
           8  reinforcing ribs 
           9  lower edge 
           10  side edges 
           20  sleeve 
           21  lower housing part 
           22  ducts 
           23  connectors 
           24  tubes 
           25  tubes 
           26  fiber management unit 
           27  inner tube 
           28  elastomer cable seal 
           29  flexible tube 
           30  cable sheath 
           31  shrink collars 
           32  shrink collars