Patent Publication Number: US-11394137-B2

Title: Device for interconnecting cables

Description:
RELATED APPLICATION 
     This application claims the benefit of priority from European Patent Application No. 19 306 035.7, filed on Aug. 27, 2019, the entirety of which is incorporated by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to interconnecting cables, in particular a device for interconnecting cables of the type having a core strand and at least one layer of strands coaxially surrounding the core strand. 
     BACKGROUND 
     There is a general need for interconnecting, joining or splicing cables. 
     Cables, such as wires for bearing mechanical load or tension, often have a core strand and at least one layer of strands coaxially surrounding the core strand. 
     Other cables, such as electric power cables, comprise one or more conductors arranged in an insulating outer sheath. The conductors of an electrical power cable may also comprise a central conductive strand, with a plurality of layers of additional strands coaxially surrounding the central strand. 
     It is often necessary to interconnect two lengths of wires or power cables with a core strand and stranded, coaxially arranged conductors. In the case of offshore wires or power cables, where the cables are extremely large and heavy, and where the physical demands placed on the cable are very great, the joint between conductors must be particularly robust and must meet exacting standards of reliability. 
     The current method for joining together stranded conductors of two sections of offshore wires or power cables is to weld together the corresponding strands from the two cable sections, often combined with a crimp ferrule. This method has certain disadvantages. Welding is a labor-intensive and time-consuming operation requiring skilled and highly trained personnel. Welding in an offshore environment, often onboard a cable laying vessel, is particularly challenging with respect to cleanliness, stability, temperature and other environmental factors. 
     It is also a challenge to weld together two conductors that have a different number or configuration of strands. 
     Hence, there is a need for a simple device for interconnecting cables of the above-mentioned type in general, and in particular a device that meets particular requirements for use with offshore wires or power cables. 
     SUMMARY OF THE INVENTION 
     The present invention provides a device for interconnecting cables of the type having a core strand and at least one layer of strands coaxially surrounding the core strand. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features and advantages of the invention will be apparent from the following detailed description of exemplary embodiments, with reference to the attached drawings, wherein: 
         FIG. 1  is a cross sectional view of a cable for use with a device according to the invention; 
         FIG. 2  is a perspective view of an embodiment of a device for interconnecting cables; 
         FIG. 3  is a cross sectional view of an embodiment of a device for interconnecting cables; 
         FIGS. 4A , B and C are various views illustrating a cylindrical segment; 
         FIGS. 5A , B and C are various views illustrating a central tightening member; 
         FIGS. 6A , B and C are various views illustrating an inner conical member; 
         FIGS. 7A , B and C are various views illustrating an intermediate conical member; 
         FIGS. 8A , B and C are various views illustrating an end piece; 
         FIG. 9  is a perspective view illustrating various aspects of tightening and engagement means. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a cross sectional view of a cable for use with a device according to the invention. 
     As illustrated in  FIG. 1 , the cable  100  is of the type having a core strand  110  and at least one layer of strands  120  coaxially surrounding the core strand  110 . In the illustrated example, the cable has a core strand  110 , a first layer of strands  120  coaxially surrounding the core strand  110 , and a second layer of strands  130  coaxially surrounding the core strand  110  and the first layer of strands  120 . The cable may however have only a core strand  110  and a first layer of strands  120  coaxially surrounding the core strand, or it may include any number of additional, outer layers of strands. The strands may typically be made of a metallic material, e.g. an alloy, such as steel. The strands may be made of the same material, or different strands may be made of different materials. For instance, the core strand may be made of steel while the outer layers of strands may be made of another metal or alloy. 
     The cable  100  may serve as a wire, with the purpose of bearing mechanical loads or tension, or it may serve as an electrical conductor, in particular for transferring electric power. An outer sheath  140  may in some cases be arranged outside the outermost layer of strands. If the cable is an electric power cable, the outer sheath  140  may typically be an insulation sheath, made of an electrically insulating material. 
       FIG. 2  is a perspective view of an embodiment of a device for interconnecting cables. 
     The device  200  is for interconnecting cables of the type shown in  FIG. 1 , i.e., cables having a core strand  110  and at least one layer of strands  120 ,  130  coaxially surrounding the core strand  110 . The device  200  comprises a central tightening member  330  and first and second cylindrical segments  340 . Each cylindrical segment  340  has an opening  360  for insertion of an end of a cable  100  at its distal end, i.e., its end facing away from the central tightening member  340 . Each cylindrical segment  340  is tightenably connected to the central tightening member  330  at its central end, i.e., at its end directed towards the central tightening member  330 . 
     Also shown in  FIG. 2  are two segments of cables  100 , of the type also illustrated in  FIG. 1 . Each cable  100  has a core strand  110  and two layers of strands  120 ,  130  coaxially surrounding the core strand  110 . 
     When used with the device  200 , the strands of the cables  100  are advantageously cut to same length before the strands are inserted into the device. 
       FIG. 3  is a cross sectional view of an embodiment of a device for interconnecting cables. 
     Corresponding to what is shown in  FIG. 2 , the device  200  is for interconnecting cables of the type having a core strand  110  and at least one layer of strands  120 ,  130  coaxially surrounding the core strand  110 . The device  200  comprises a central tightening member  330  and first and second cylindrical segments  340 . Each cylindrical segment  340  has an opening  360  for insertion of an end of a cable  100  at its distal end. Each cylindrical segment  340  is tightenably connected to the central tightening member  330  at its central end. 
     An inner conical member  310  is arranged within each cylindrical segment  340 . The inner conical member  310  has a central bore arranged for insertion of an end of the core strand  110  of the cable  100 . The inner conical member  310  further has an outer sloping surface on which the first layer of strands  120  coaxially surrounding the core strand  110  of the cable may be positioned when the device is used to interconnect the two cable segments  100 . 
     Further, a cylindrical end piece  350  is arranged within each cylindrical segment  340 . The end piece  350  is arranged within the distal end of the cylindrical segment, and may typically rest against an internal flange, ridge or rim arranged at the distal end of the cylindrical segment  340 . The end piece  350  may be a separate part mounted within the cylindrical segment  340 , or it may be an integrated portion of the cylindrical segment  340 . In any case, the end piece  350  has a central bore arranged for insertion of the cable, corresponding to the opening  360  in the cylindrical segment  340 . Further, the end piece  350  further has an inner sloping or inner conical surface. One of the layers of strands coaxially surrounding the core strand  110  of the cable may be positioned on the inner sloping surface of the end piece  350 . 
     In the embodiment shown in  FIG. 3 , which is useful for cables with one central strand and two layers  120 ,  130  of additional, coaxial strands, the device  200  also includes an intermediate conical member  320  is arranged within each cylindrical segment  340 . The intermediate conical member  320  has a central bore arranged for insertion of the core strand  110  and the first or intermediate layer of surrounding strands  120  of the cable. The intermediate conical member  320  further has an inner sloping or inner conical surface on which the intermediate layer of strands  120  that coaxially surrounds the core strand  110  of the cable is positioned during use. The intermediate conical member further has an outer sloping or conical surface on which the outermost layer of strands  130  that coaxially surrounds the core strand  110  of the cable is positioned. 
     If the cables used with the device  200  includes additional layers of coaxially arranged strands, the device  200  may further include additional conical members arranged within each cylindrical segment  340 . In this case, each additional conical member may correspond to an additional layer of surrounding strands of the cable. The additional conical member may have the same shape and construction as the conical member  320 . 
     Advantageously, all the conical members have essentially the same slope on their outer surfaces. Also, the conical members advantageously have rear conical openings with an inner slope arranged to accept the forward conical portion of an adjacent conical member. 
     The central tightening member  330  and the cylindrical segments may be axially tightened in such a way that the inner conical member  310  and the end piece  350  will be axially pressed together with the layer of strands  120  coaxially surrounding the core strand  110  sandwiched between them, resulting in a stable interconnection of the cables&#39; ends. 
     In order to obtain the axial tightening, the central tightening member  330  may suitably be provided with threads, and the first and second cylindrical segments  340  are provided with corresponding threads that are mateable with the threads of the central tightening member  330 . The axial tightening of the central tightening member  330  is in this case achieved by relative rotation between the central tightening member  330  and the first and second cylindrical segments  340 . Typically, the central tightening member  330  may be provided with external threads and the first and second cylindrical segments  340  may be provided with internal threads. In order to provide a beneficial tightening function, the central tightening member  330  advantageously has flat surfaces at its axial ends, as shown in  FIG. 3 . 
       FIGS. 4A , B and C are various views illustrating a cylindrical segment  340 .  FIG. 4A  is a perspective view of the cylindrical segment  340 .  FIG. 4B  is a cross sectional view of the cylindrical segment  340 .  FIG. 4C  is an end view of the cylindrical segment  340 . 
       FIGS. 5A , B and C are various views illustrating a central tightening member  330 .  FIG. 5A  is a perspective view of the central tightening member  330 .  FIG. 5B  is a cross sectional view of the central tightening member  330 .  FIG. 5C  is an end view of the central tightening member  330 . 
       FIGS. 6A , B and C are various views illustrating an inner conical member  310 .  FIG. 6A  is a perspective view of the inner conical member  310 .  FIG. 6B  is a cross sectional view of the inner conical member  310 .  FIG. 6C  is an end view of the inner conical member  310 . 
       FIGS. 7A , B and C are various views illustrating an intermediate conical member  320 .  FIG. 7A  is a perspective view of the intermediate conical member  320 .  FIG. 7B  is a cross sectional view of the intermediate conical member  320 .  FIG. 7C  is an end view of the intermediate conical member  320 . 
       FIGS. 8A , B and C are various views illustrating an end piece  350 .  FIG. 8A  is a perspective view of the end piece  350 .  FIG. 8B  is a cross sectional view of the end piece  350 .  FIG. 8C  is an end view of the end piece  350 . 
     The device  200  and its components, i.e. the central tightening member  330 , the first and second cylindrical segments  340 , the inner conical member  310 , the cylindrical end piece  350  and any further conical members such as the intermediate conical member  230 , may be made of suitable materials according to use requirements, including hardness, tensile strength, etc. In many applications, various steel materials, e.g. stainless steel, may be applicable for the device  200  and its components. 
       FIG. 9  is a perspective view illustrating various aspects of tightening and engagement means. 
       FIG. 9  illustrates an embodiment  900  of the device  200  which includes various engagement means  910 ,  920 ,  930 . In order to facilitate the tightening function of the device  200 , the central tightening member  330  and the first and second cylindrical segments may include engagement means for engagement with corresponding tightening tools. As shown in  FIG. 9 , the engagement means may for instance include collars  910 ,  920  provided on outer surfaces of the central tightening member  330  and the first and second cylindrical segments  340 . 
     As shown in  FIG. 9 , the central tightening member  330  may have a hex collar  910  for engagement with a wrench or other external tightening device (not illustrated). In certain embodiments, one or both cylindrical segments  340  are required to have a smooth outer surface, for example where the cylindrical members are to be covered with a sheath or in other situations where the diameter of the cylindrical segments is of concern. In such situation a dedicated tightening tool may be employed to grip the smooth outer surface of the cylindrical segments  340  for tightening. In alternate embodiments, such as shown in  FIG. 9 , one or both of the cylindrical segments  340  may also be equipped with a hex collar  920  for engagement with a wrench or other external tightening device. Alternatively, other means for engaging an external tightening device may be provided, for example holes as illustrated at  930 , arranged to receive pins from the external tightening device. The two cylindrical segments  340  may have different engagement means or identical engagement means, depending on use requirements. 
     The present specification also discloses a device  200  as described above, used to interconnect two cables. This results in a spliced cable, including two cables of the type having a core strand  110  and at least one layer of strands  120  coaxially surrounding the core strand  110  and a device as disclosed on the above specification for interconnecting the cables.