Patent Publication Number: US-6213808-B1

Title: Method of joining electrical conductors and an apparatus for practicing this method

Description:
FIELD OF THE INVENTION 
     This invention relates to a method of joining electrical conductors and an apparatus for practising this method. 
     BACKGROUND OF THE INVENTION 
     The provision of a telephone service generally involves routing a cable having multiple electrical conductors from an external network connection into a building where the service is required. 
     In the past externally mounted terminal blocks have been used for linking a cable coming from a telephone pole, for example, to conductors leading into the building concerned. Each terminal block may include an array of metal strips embedded in an insulating body, with each strip having a pair of screws for securing the terminations of respective conductors. 
     Other connecting systems include terminal blocks comprising a body of insulating material equipped with built-in metallic fasteners having notched cutting edges for piercing the electrical insulating sleeves surrounding the conductors in order to establish the required electrical contact. These systems eliminate the previously required installation step of stripping the insulation off conductor ends before joining them. 
     Connectors having exposed metal portions remain susceptible to moisture penetration, and resultant undesirable stray electrical currents. More recent connecting systems accordingly provide individual connectors, each having an insulating body encasing a displaceable blade-like metal element. In use the metal element first strips the insulation off the terminations of electrical conductors, and then forms an electrical link between them. 
     The present invention seeks to provide a method and an apparatus to facilitate and simplify the installation of electrical cables, and joining their respective conductors as required. 
     SUMMARY OF THE INVENTION 
     The present invention provides a method of joining electrical conductors to each other by means of existing connectors which are receivable in a common housing having a base portion and a matching cover portion, and each connector includes a casing holding captive a displaceable element for locking together the terminations of the conductors, the said method including the steps of 
     inserting respective terminations of the conductors into corresponding apertures defined by the casing of each connector; 
     positioning each connector in a complementary recess formed by the base portion of the housing; and 
     applying an external force to the displaceable element of each connector by means of a tool which is operable by means of the cover portion of the housing until the displaceable element electrically joins together the terminations of the respective conductors. 
     The steps set out above are conveniently applied sequentially to join the respective conductors of at least 2 multi-cored cables with each other. An installation process involving these steps may include a final step of securing the cover portion of the housing to the base portion to form a weather-proof enclosure for the connectors and their associated conductors. 
     The invention extends to an electrical housing for joining electrical conductors by means of existing connectors, wherein each connector has a casing holding captive a displaceable element for joining together terminations of at least two conductors at a time, the said housing including 
     a base portion defining complementary recesses for respectively receiving the connectors; 
     a cover portion matching the base portion to form an enclosure for accommodating the connectors; and 
     a tool which is operable by the cover portion during use to apply an external force to the displaceable element of each connector in order to join together the conductor terminations located within each connector. 
     The base portion may include a mounting plate supporting tubular elements defining recesses for the connectors. 
     The cover portion preferably fits in complementary relationship on to the base portion. The housing preferably includes securing means for securing the cover portion to the base portion during use. 
     The cover portion may define at least one port for inserting a cable comprising 2 or more conductors. 
     The tool may be integrally connected to the housing, and arranged immediately adjacent to at least one port. The tool may include a peripheral ridge formation matching the external dimensions of the casing of each connector to allow the tool to be centred over the displaceable element before any force is applied to the displaceable element. 
     In other embodiments of the invention the tool may be temporarily located in a cable port in the housing, and removed after use. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is described below by way of example with reference to the accompanying diagrammatic drawings, in which 
     FIG. 1 shows an exploded perspective view of an electrical housing according to the present invention; 
     FIG. 2 shows a perspective view on an enlarged scale, illustrating the application of a tool forming part of the housing shown in FIG. 1; and 
     FIG. 3 shows a schematic view of an electrical connector used in conjunction with the present invention, illustrating more fully the application of the tool shown in FIG.  2 . 
    
    
     DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION 
     In the accompanying drawings reference numeral  10  generally identifies an electrical housing according to the present invention. The housing  10  includes a base portion  12 , a matching cover portion  14  and a locking device  16  for securing the cover portion to the base portion. 
     The base portion  12  includes a rectangular mounting plate  18  of a moulded plastics material, which supports  4  upstanding tubular elements  20 . Each tubular element  20  defines a socket  22  for receiving an electrical connector  24  of known design. Connectors of this kind are commercially available from France, and are sold as telecommunication connectors under the trade name ETON. 
     Each connector  24  has an outer casing of a moulded plastic material forming a cylindrical portion  26  which is integrally connected to a nozzle portion  28  for receiving the terminations of an electrical conductor  30 , as illustrated in FIG.  2 . In use the nozzle portion  28  of each connector  24  nests in a corresponding recess  32  in its associated tubular element  20 . 
     A displaceable locking element  34  resembling a cylindrical plunger is held captive by the outer cylindrical portion  26  of the connector casing. In use, the element  34  co-operates with a metal blade (not shown) arranged within the connector casing in transverse relationship to the nozzle portion  28 . 
     When downward pressure is applied to the displaceable element  34  the blade tends to fold the terminations of the conductors  30  located within the connector casing over a static plate (not shown) in order to prevent inadvertent, subsequent extraction of the conductors  30 . This step is conveniently performed manually. 
     The conductors  30  only become fully joined after the application of further pressure to the displaceable element  34 . As the element  34  advances into the connector casing it performs a shearing action on the folded portion of each conductor  30 . In doing this the movable blade strips any outer insulating material from the conductors  30  while maintaining continuous, simultaneous electrical contact with their respective metal cores. 
     Each connector  24  may be optionally filled with a non-conducting grease, which is expelled in extrusion-fashion from the nozzle portion  28  of the connector as the displaceable element  34  is urged into the connector casing. The electrical connection between the conductors  30  is accordingly rendered substantially moisture proof. 
     The final actions on the displaceable element  34  generally require more force than can be exerted manually in order to overcome any inherent frictional resistance. The present invention provides a convenient tool for this purpose, which is operable by means of the cover portion  14  of the housing  10 . 
     The cover portion  14  is generally rectangular in configuration, and is preferably made of a moulded plastics material. An upstanding flange formation  36  on the mounting plate  18 , which is arranged adjacent to its peripheral edges, serves to locate the housing  14  during use. 
     The cover portion  14  defines two opposing ports  38  having an inverted U-shaped profile, for inserting cables containing multiple conductors  30 . Each port  38  is surrounded by an outwardly projecting tool formation  40 , having a regular cross sectional profile throughout its length, and an inner wall generally coinciding with the profile of the ports  38 . 
     Each tool formation  40  further defines a generally U-shaped ridge  42  which coincides with the outer peripheral area of the formation. The function of the tool formation  40  is best understood with reference to FIGS. 2 and 3. 
     FIG. 2 shows a connector  24  having 2 conductors  30  located in the nozzle  28  and provisionally locked in position in the manner described above. The cover portion  14  of the housing  10  is manipulated so that one of the tool formations  40  is positioned immediately above the connector  24 , as demonstrated in FIG.  2 . 
     The inner edges of the ridge  42  are generally dimensioned to pass with clearance over the outer peripheral region of the cylindrical portion  26  of the connector  24 . The adjacent surface of the tool formation  40  is sufficiently wide to maintain steady contact with the displaceable element  34  during use. 
     Once a downward force is manually applied to the cover portion  14  the tool formation  40  gradually advances from an initial position depicted in broken outline in FIG. 3 to a final position in which the upper surface of the displaceable element  34  lies virtually flush with the adjacent surface of the cylindrical portion  26  of the connector  24 . 
     At this stage the movable blade inside the connector is in intimate contact with the metal cores of both conductors  30 , and their terminations are firmly locked in place, and electrically joined to each other. The connectors  24  are conveniently positioned in respective sockets  22 , as illustrated in FIG.  1 . The mounting plate  18  accordingly provides a solid backing for each connector  24  before the final locking force is applied. Using the tool formation  40  on the cover portion  14  in conjunction with the base portion  12  in the manner described above dispenses with the need for specialised crimping tools or the like to firmly lock each connector during installation. 
     The conductors  30  are contained inside incoming cables  44  which pass through respective gaps in the flange formation  36  on the mounting plate  18 . Two deflection plates  46  guide the cables around corresponding pins  48 , which are integrally connected to the mounting plate  18 . These pins provide relief for the cable terminations against any external, tensile forces applied to the cables  44 . 
     Once all required connections between respective conductors  30  have been established in the manner described above the housing  14  is lowered on to the mounting plate  18 . The cables  44  eventually pass through the ports  38  in the housing  14 , and the flange formation  36  nests with slight clearance inside the housing. 
     The locking device  16  has a pair of resilient prongs  50  with catches  52  which are receivable in a corresponding socket formed by an upstanding tubular member  54  on the mounting plate  18 . The tubular member  54  is located immediately below an aperture  56  in the housing  14  through which the prongs  50  are insertable. 
     Once the locking device  16  is pushed fully downwardly the catches  52  engage the tubular member  54  by way of opposing lateral recesses  58  cut out of the tubular member. The cover portion  14  is accordingly locked in position, denying any unauthorised access to the cable terminations within the junction box  10 . Any subsequent access is only feasible by destroying the locking device  16 . 
     The electrical housing  10  described above lends itself to various modifications and adaptations. It is feasible, for example, to provide up to  10  connector sockets per electrical housing for relatively large numbers of telephone installations. The corresponding size of the ports  38  will necessarily increase to the extent that a correspondingly larger tool formation would no longer fit on to the connectors  24 . 
     In this case it is preferable to provide a detachable insert, preferably of a moulded plastics material, which is temporarily locatable in a corresponding port in order to apply the required force to the connectors  24  during use. Electrical housings according to the present invention are preferably sold as complete kits. If a detachable tool is required, this may be conveniently discarded after use. 
     Each electrical housing may further be provided with double-sided adhesive tape for securing the mounting plate  18  to a selected support structure or substrate. In this way housings and telephone lines can be installed with comparative ease using only the contents of each kit. 
     A skilled reader will appreciate that the embodiments described above permit even further modifications and adaptations without dispensing with the elements set out under the summary of the invention. The scope of the accompanying claims should accordingly not be construed as being limited in any manner by the features of the preferred embodiments described above.