Abstract:
An electrical connector for an electrical conductor cable. The connector comprises a housing, an electrical contact subassembly, a first ferrule, and a retention member. The electrical contact subassembly is connected to the housing and electrically connectable to electrical conductors in the cable. The first ferrule is adapted to be compressed onto the cable around an outer insulation of the cable. The retention member is adapted to capture the ferrule between the retention member and to exert a compression force on the ferrule towards the cable. The retention member could be a pair of inserts removably mounted to the housing or could be unitarily formed with the housing.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to electrical connectors and, more particularly, to a system for connecting an electrical connector to an electrical conductor cable.  
           [0003]    2. Brief Description of Prior Developments  
           [0004]    U.S. Pat. No. 4,272,148 discloses a shielded connector housing for use with a multiconductor shielded cable. A ferrule is located on the cable and ends of shield wires are bent back onto the ferrule. The shield wires and ferrule are compressed by a ridge of the housing as housing pieces are connected to each other. Some types of electrical connectors require an over-molded strain relief to be formed on the cable to attach to a connector housing. However, over-molding a strain relief feature onto a cable adds costs to the manufacturing process. Some other types of electrical connectors have teeth that project into the cable to form a strain relief. However, such teeth can change the impedance of the conductors in the cable. FCI USA, Inc. sells electrical connectors under the trademark METAGIG. The METAGIG connectors include a printed circuit board surrounded by shields inside a housing. There is a desire to reduce assembly costs and time for manufacturing such connectors by providing strain relief, without over-molding a strain relief onto the cable and without teeth compressing a cable, while still providing shielding for a printed circuit board, but without complicating the connection of the connector to the cable.  
         SUMMARY OF THE INVENTION  
         [0005]    In accordance with one embodiment of the present invention, an electrical connector is provided for an electrical cable. The connector comprises a housing, an electrical contact subassembly, a first ferrule, and at least one ferrule retention member. The electrical contact subassembly is connected to the housing and electrically connectable to electrical conductors in the cable. The first ferrule is adapted to be compressed onto the cable around an outer insulation of the cable. The at least one ferrule retention member is adapted to capture the ferrule therein and to exert a compression force on the ferrule towards the cable. The at least one ferrule retention member is located inside the housing.  
           [0006]    In accordance with another embodiment of the present invention, an electrical cable assembly is provided comprising an electrical cable; and an electrical connector connected to the cable. The electrical connector comprises a housing, an electrical contact subassembly connected to the housing and electrically connected to conductors in the cable, a ferrule connected to the cable around an outer insulation of the cable, and a cable retention member mounted in the housing and surrounding the ferrule. The ferrule is compressed onto the cable and forms a compression frictional retention with the cable. The cable retention member exerts a compression force on the ferrule.  
           [0007]    In accordance with one method of the present invention, a method of assembling an electrical connector and cable assembly is provided comprising steps of connecting a ferrule around an outer insulating cover of an electrical conductor cable by compressing the ferrule; connecting contacts to electrical conductors of the cable; locating a retention member around the ferrule; and inserting the retention member, the ferrule, the contacts and a portion of the cable into a connector housing, wherein the housing presses the retention member inwardly to exert a compression force onto the ferrule and to retain the ferrule inside the housing. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    The foregoing aspects and other features of the present invention are explained in the following description, taken in connection with the accompanying drawings, wherein:  
         [0009]    [0009]FIG. 1 is a perspective view of a connector and cable assembly having an electrical connector incorporating features of the present invention;  
         [0010]    [0010]FIG. 2 is an exploded perspective view of the assembly shown in FIG. 1;  
         [0011]    [0011]FIG. 3 is a schematic cross-sectional view of parts of the assembly shown in FIG. 1;  
         [0012]    [0012]FIG. 4, is a schematic cross-sectional view of parts of an alternate embodiment of the present invention;  
         [0013]    [0013]FIG. 5 is a schematic partial cross-sectional view of an alternate embodiment of the present invention;  
         [0014]    [0014]FIG. 6 is a schematic partial cross-sectional view of the another alternate embodiment of the present invention;  
         [0015]    [0015]FIG. 7 is a partial cross-sectional view of another alternate embodiment;  
         [0016]    [0016]FIG. 8 is perspective view of an alternate embodiment of the present invention; and  
         [0017]    [0017]FIGS. 9A and 9B are exploded perspective views of an alternate embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]    Referring to FIG. 1, there is shown a perspective view of an electrical connector and cable assembly  10  having an electrical connector  12  incorporating features of the present invention. Although the present invention will be described with reference to the embodiments shown in the drawings, it should be understood that the present invention can be embodied in many alternate forms of embodiments. In addition, any suitable size, shape or type of elements or materials could be used.  
         [0019]    The assembly  10  generally comprises the connector  12  and a cable  14 . The connector  12  is connected to one end of the cable. The other end of the cable  14  could be connected to another connector or an electronic device (not shown). Referring also to FIG. 2, the cable  14  includes four conductors  16 , each having its own insulation  18 , a conductive shield or braid  20  and an outer insulation  22 . In alternate embodiments, any suitable type of cable could be provided, and the cable could have more or less than four conductors. In this embodiment the shield  20  compresses a metal braid. However, in alternate embodiments any suitable type of shielding could be provided. A portion of the outer insulation  22  is removed at the end of the cable and the braid  20  has been folded back. Insulation  18  has been removed from the conductors  16  at their ends.  
         [0020]    The connector  12  generally comprises a housing  24 , a contact subassembly  26 , a printed circuit board  28 , at least one insert  30  and a ferrule  32 . In this embodiment the housing  24  comprises three housing pieces  34 ,  35 ,  36 . However, in alternate embodiments the housing could comprise more or less housing pieces. The printed circuit board  28  can have pads  38  on its top and bottom sides. Individual ones of the conductors  16  are connected to the pads  38  in a known manner. A front end  40  of the board  28  is located in a receiving slot  46  of a support  48  of the contact subassembly  26  with contact pads  44  on the front end  40  being electrically connected to contacts  42  of the subassembly  26 . Thus, the conductors  16  are connected to the contacts  42  by the board  28 . However, in alternate embodiments, any suitable printed circuit board or other circuit substrate could be provided, or the connector might not have a printed circuit board. In addition, in alternate embodiments any suitable connection of the conductors  16  to the contacts  42  could be provided. The contact subassembly  26  and part of the board  28  are located inside the front housing piece  34 . However, in alternate embodiments, any suitable contact subassembly or contacts could be provided. The front housing piece  34  includes a cantilevered deflectable latch  50 . A rear end  52  of the latch  50  abuts against a stop  54  of the top rear housing piece  35  in a rest position. A portion  56  of the latch  50  is adapted to be contacted by a finger of a user to depress or deflect the latch to an unlatched position. However, in alternate embodiments any suitable front housing piece or latching system could be provided.  
         [0021]    Referring also to FIG. 3, the two rear housing pieces  35 ,  36  capture the inserts  30 , front end of cable  14 , and portions of the board  28  and front housing piece  34  therebetween. The two rear housing pieces  35 ,  36  are preferably cast metal parts fixedly connected to each other by fasteners, such as screws. However, any suitable fastening system could be used. The rear housing pieces  35 ,  36  press the inserts  30  towards each other. The rear housing pieces  35 ,  36  have recesses  58  at their rear ends which are preferrably precisely sized and shaped for the outer diameter of the cable. However, the recesses  58  might be slightly larger or smaller.  
         [0022]    The ferrule  32  is preferrably comprised of metal, but any suitable conductive material could be used. The inner diameter of the ferrule  32  is preferably about the same size as the outer diameter of the cable  14 , but could be slightly larger or smaller. The ferrule  32  is preferably compressed or crimped onto the cable  14 . However, even after compression of the ferrule onto the outer insulation  22  of the cable  14 , the inner diameter of the ferrule  32  is only slightly less than the outer diameter of the outer insulation  22  before compression of the ferrule. In addition, the interior of the ferrule  32  is smooth. Therefore, the outer insulation  22  is not pierced into by the ferrule and the ferrule  32  only slightly compresses the outer insulation  22 . Preferably, the compression of the ferrule  32  is substantially uniform along a majority of the length of the ferrule. Thus, a substantially uniform frictional retention is provided between the inner surface of the ferrule and the outer insulation  22 . However, in alternate embodiments any suitable attachment of the ferrule to the cable could be provided. In alternate embodiments more than one ferrule could be provided. The ferrule  32  is slid onto the cable  14  and crimped thereto. Then, the shield  20  is folded back onto the outer surface of the ferrule.  
         [0023]    The insert  30  preferably comprises two inserts  30  formed of cast metal members. However, in alternate embodiments the inserts could include any number of inserts and may be comprised of any suitable conductive material and could be formed by any suitable process. However, the inserts preferably comprise ferromagnetic material. In this embodiment the connector  12  has two of the inserts, but more than two inserts could be provided. In this embodiment the inserts are substantially mirror images of each other. However, in alternate embodiments, the inserts could have different shapes. In the embodiment shown, each insert comprises a main channel  60  with a center section  62 , a front section  64  and a rear section  66 . The main channel  60  is deeper at the center section  62  than the front and rear sections. In a preferred embodiment, when the two inserts  30  are pressed against each other by the housing  24 , the rear sections  66  form an aperture having a diameter which is about the same size as, or slightly less than, the outer diameter of the cable  14 . In addition, the center sections  62  combine to form an area with a diameter that is less than the diameter of the cable/ferrule/shield ( 14 / 30 / 20 ) between the center sections  62 . Therefore, the center sections  62  compress the exposed portion of the shield  20  inward against the outer side of the ferrule  32 . This results in the exposed folded back portion of the shield  20  being clamped between the inserts  30  and the ferrule  32 .  
         [0024]    Because the shield  20  is clamped between the ferrule  32  and the inserts  30 , this interlocks the cable  14  with the inserts  30 . This allows the ferrule  32  to be attached to the outer insulation  22  of the cable  14  by a general uniform circular crimp. Such crimp secures ferrule  32  to cable  14  without an excessively large or deep compression, without piercing into the outer insulation, and without damaging the braid. The combination of the shield  20  being clamped between the ferrule  32  and the inserts  30 , as well as the moderate crimp or compression of ferrule  32  on the outer insulation for a frictional retainment, provide sufficient forces to retain the ferrule  32  and cable  14  together. The surface  68  at the front end of the rear section  66  forms a stop surface for contacting the rear end of the ferrule  32 . This prevents the cable  14  from being pulled out of the connector  12 . The rear sections  66  also form a strain relief for the cable  14 , but without piercing into the outer insulation  22  and without the need for over-molding a strain relief section onto the cable. With the embodiment described above, the ferrule  32  functions as an inner ferrule and the inserts  30  function as an outer ferrule to seal off or shield the cable and, at the same time, form a cable strain relief. The interlocking of the ferrules and the cable reduces the amount of EMI.  
         [0025]    This embodiment, unlike other connectors which allow pull forces to be distributed through the cable and conductors, allows pull forces on the cable to be distributed through the inserts to the housing. The present embodiment also allows for a more even distribution of the braid shielding  20 ; unlike existing designs which cut into the braid. With the present invention, the ferrule, inserts and housing do not significantly damage, crush or kink the cable and, therefore, will not change impedance of the conductors.  
         [0026]    This is particularly important as signal speeds increase. In a preferred method of manufacturing the assembly  10 , the inserts  30  and ferrule  32  are selected from a plurality of different size inserts and ferrules for different size cables, such that the inserts and ferrule provide the strain relief and anti-pullout features for the cable as described above.  
         [0027]    In this embodiment the front sections  64  surround the exposed ends of the conductors  16  and the rear part of the board  28 . The surfaces  70  form a stop for the front end of the ferrule  32 . Because the inserts preferrably comprise ferromagnetic material and are electrically connected to the shield  20 , they form a shield surrounding the connection of the conductors  16  onto the pads  38 . FIG. 4 shows an alternate embodiment wherein the inserts  30 ′ extend forward past the connection of the conductors  16  to the board  28  to provide a shield for a longer length of the board  28 .  
         [0028]    Referring now to FIG. 5, an alternate embodiment of the present invention is shown. In this embodiment the connector comprises two inserts  70 , an inner ferrule  72  and an outer ferrule  74 . The inner ferrule  72  is slid onto the outer insulation of cable and crimped thereto. The shield  20  is folded back onto the inner ferrule  72 . The outer ferrule  74  is then placed over the shield  20  and the inner ferrule  72  and crimped or compressed. The inner ferrule prevents the cable from being crushed when the outer ferrule is compressed. The two ferrule fixedly sandwich the exposed shield  20  therebetween. With this embodiment the inserts  70  do not need to press against the shield or ferrule(s), but can still be located against the outer insulation  22  of the cable  14  at their rear ends  76  to form a strain relief.  
         [0029]    Referring now to FIG. 6, another alternate embodiment is shown. In this embodiment the shield  20  of the cable  14  is folded back onto the outer insulation  22  and the ferrule  78  is placed over the exposed shield  20 . The ferrule  78  is then compressed onto the shield  20 . Because of the irregular surface of the shield  20 , the ferrule  78  forms a good frictional engagement with the shield  20  to help assist is preventing the ferrule from sliding off of the exposed shield  20 . In addition, the inserts  80  are pressed towards each other to provide a compression force against the ferrule  78 . This compression force is distributed by the ferrule  78  against the shield  20  and, thus, against the cable, but as a more evenly distributed compression force to prevent deformation of the cable  14  which might otherwise change conductor impedance. The inserts  80  have stop surfaces  82  for contacting the rear end of the ferrule  78  and preventing pull-out. The inserts  80  also include surfaces  84 ,  86  which contact the outer insulation  22  of the cable  14  and form a strain relief.  
         [0030]    Referring now to FIG. 7, another feature of the present invention is shown. In this embodiment the housing  24 ′ includes an actuator or slider  90  attached to the top rear housing piece  35 ′. In this embodiment the slider  90  is biased in a rearward position by a spring  92 . However, in an alternate embodiment a spring might not be provided or any suitable type of spring could be used. The front end  94  of the slider  90  has a bottom surface  96  which is ramp shaped. The surface  96  contacts the latch  50 ′ proximate the finger contact section  56 ′. When the slider  90  is slid forward on the housing piece  35 ′, the ramp surface  96  deflects the latch  50 ′ downward. The slider  90  may extend to the rear end (not shown) of the housing  24 ′. With this feature, the user can deflect the latch  50 ′ by either directly pressing against the finger contact section  56 ′ or by moving the slider  90  forward. Use of the slider  90  can be beneficial when another connector or item is located directly above the finger contact section  56 ′ which prevents a user from directly contacting the finger contact section  56 ′ with his or her finger. However, the user does not need to use the slider  90  if the finger contact section  56 ′ is accessible. In alternate embodiments any suitable type of remote delatching actuator could be used.  
         [0031]    Referring now to FIG. 8, a perspective view of an alternate embodiment of the present invention is shown. In this embodiment the assembly  100  generally comprises the connector  102  and the cable  14 . The connector  102  is substantially similar to the connector  12 , but the latch  50 ′ includes a rear end extension  51 . The housing  24 ′ has a recess  53  which the rear end extension  51  is located in and is movable up and down in. The extension  51  has a user contact section  55  which extends out of the rear end of the housing  24 ′. A user can depress the user contact section  55  to move the latch  50 ′ downward to thereby disengage the latch  50 ′ from the mating socket (not shown).  
         [0032]    Referring now to FIGS. 9A and 9B, another embodiment of the present invention is shown. In this embodiment the connector comprises a member  110  which forms both the housing and the retention for the ferrule and cable. The combined member  110  generally comprises a bottom member  112  and a top member  114 . The two members  112 ,  114  are both preferably provided as one piece members and are comprised of cast conductive metal. The bottom member  112  generally comprises a housing section  116  and an integrally formed retention section  118 . The retention section  118  has an rear end aperture  120 , a cable receiving area  122 , and two fastener receiving holes  124 . The cable receiving area  122  has projections  126 . The top member  114  generally comprises a housing section  128  and an integrally formed retention section  130 . The retention section  130  has two fastener receiving holes  132 , a rear end extension  134  and projections  136 . When the two members  112 ,  114  are assembled, the projections  126 ,  136  can clamp onto an inner ferrule surrounding the cable; similar to that shown in FIGS.  3 - 6 . This embodiment illustrates that the ferrule/cable retention feature does not need to be provided as separate inserts, but could be integrally formed with the rest of the housing members.  
         [0033]    It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.