Abstract:
An electrical connector housing assembly is provided having a plug assembly and cap assembly matable with one another to form a wire to wire, wire to board or wire to device connection. The plug assembly is formed with a latching member thereon, while the cap assembly is formed with a connector position assurance device (CPA) thereon. The overall envelope of the connector housing assembly is reduced by dividing the latch member and CPA between the plug and cap housings. Keying features are formed integrally with plug and cap terminal position assurance devices (TPAs) to ensure proper orientation between the plug and cap and to further assure that each plug is connected to the corresponding cap. The overall envelope is further reduced by forming the keying features internal to the housings upon the TPAs.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The preferred embodiments of the present invention generally relate to electrical connectors with one or more terminal and connector position assurance features. More particularly, a connector position assurance device (CPA) is provided affording a low vertical profile and a terminal position assurance device (TPA) is provided including integral keying features.  
           [0002]    A CPA functions to assure an operator that the matable connector halves have been mated which is particularly advantageous on an assembly line where the operator must make connections quickly and be certain that electrical connections are, in fact, mated. It is desirable that the CPA be compact in size and eliminate the risk of inadvertent separation of the connector halves by separately preventing deflection of any latches used to maintain the mated condition.  
           [0003]    In many applications, several connectors (including plugs and associated headers) may be routed to a common area, such as on a vehicle. All of the connectors are connected when the vehicle reaches a designated point along an assembly line. In certain instances, a need has arisen for assembly line personnel to be able to distinguish between connectors to ensure that each plug is inserted into an associated and correct header. In the past, assembly line personnel have experienced difficulties in discriminating each plug and the associated header from other plugs and headers.  
           [0004]    Many conventional connector configurations have been proposed, such as for plug-header assemblies for wire-to-wire connections, plug-header assemblies for wire-to-printed circuit board connections (such as in board applications), and plug-device assemblies (such as sensors and the like). Hereafter the terms plug and cap shall be used to refer generically to any and all connector applications, including, but not limited to, wire to wire, PCB to wire, plug to device, and the like. Some conventional connectors include connector position assurance systems, such as described in U.S. Pat. No. 6,004,153; and U.S. Pat. No. 5,643,003. The &#39;003 patent and the &#39;153 patent, as in conventional CPA systems, include a plug housing with a latch formed thereon. The latch slidably receives a CPA which is mounted to the plug housing and is operable to assure that a further matable connection is fully mated to the housing before the CPA may be moved to its engaged position.  
           [0005]    However, conventional CPA and latch assemblies require a CPA carriage structure formed on top of the latch assembly, or visa versa. Typically, latches are formed to be moved toward and away from the plug housing, and thus the CPA is mounted above or below the latch to block such vertical motion. Stacking the CPA and latch upon one another unduly increases the overall envelope of the connector. With increasing demands being placed on miniaturization of connectors, a need exists to continue to further reduce the outer envelope of the connector device.  
           [0006]    In assembly line applications, it is desirable to facilitate the visual inspection by an assembly line person of a plurality of connector devices. Conventional CPA shrouds are configured to direct the CPA inward into the CPA shroud assembly whereby the CPA shroud hides a substantial majority of the CPA structure. Consequently, during an assembly line application, it is difficult to visually determine whether a CPA has been fully engaged, and thus it is difficult to visually determine whether a plug and cap are properly fully mated.  
           [0007]    In addition, in assembly line applications, it is desirable to ensure that the assembly line person insert the plug and cap housings in proper orientation with respect to one another. Conventional connectors have been proposed with keying features that ensure proper orientation between the plug and cap housings before permitting full mating engagement therebetween. However, such conventional keying features are provided on the plug and cap housings, thereby increasing the overall envelope of the connector device. A need exists to reduce the envelope of the connector device while ensuring that the plug and cap housings may be fully mated only when properly aligned.  
           [0008]    Conventional connectors have been proposed that include terminal position assurance devices (TPA) which are received within the plug housing and engaged to the connector contacts. TPAs ensure that connector wires are properly and fully mated within a plug housing before permitting the TPA from being moved to an engaged position. In the past, TPAs (also referred to as wedges) when provided to a manufacturer of a connector device are delivered entirely separate from the plug and cap housings. The TPAs (or wedges) are inserted into the plug and cap housings immediately before insertion of the contacts and wires. A need exists for an improved TPA that may be assembled with a plug and cap housing separate and apart from insertion of the contacts and wires.  
           [0009]    A need remains for improved CPA and TPA features for connector assemblies that overcome the problems discussed above. The preferred embodiments of the present invention described below address the above discussed needs and other disadvantages of conventional connector devices that will become readily apparent from the following description, drawings and claims.  
         BRIEF SUMMARY OF THE INVENTION  
         [0010]    An electrical connector housing assembly is provided that includes a connector position assurance device (CPA) having a reduced overall envelope. The housing assembly includes a plug housing and a cap housing, each of which have top, bottom and side walls defining a mating interface therebetween. One of the plug and cap housings are formed with a deflectable latch formed thereon, while the other of the plug and cap housings are formed with a CPA carriage or retainer. A CPA is retained within the CPA carriage structure and is moveable relative to the carriage structure between an initial disengaged position and a final engaged position indicating that the plug and cap housings have been properly mated with one another.  
           [0011]    In accordance with at least one alternative embodiment, an electrical connector housing assembly is provided having plug and cap housings with top, bottom and side walls defining a mating interface therebetween. The plug and cap housings each receive terminal position assurance devices (TPAs). Plug and cap TPAs are formed integrally with keying features, such as a keying post and keying opening that ensure proper orientation between the plug and cap assemblies before permitting mating. The keying features on the plug and cap TPAs may be varied between plugs and caps in a single application to uniquely identify which cap is to be associated with each plug. By including keying features on the TPAs, the overall envelope of the connector housing assembly is reduced while offering the advantages of a keying configuration.  
           [0012]    In at least one alternative embodiment, the CPA retaining structure includes a pair of guide rails aligned parallel to one another and mounted on a top wall of the cap housing. The guide rails include juxtaposed channels cut therein and defining a guide way that slidably receives flanges along opposite sides of a CPA. The CPA is moveable within the guide way between an initial position at which the CPA is substantially enclosed within the guide rails and a final engaged position at which the CPA partially projects from the guide rails to facilitate visual inspection of the CPA&#39;s present state. The plug and cap assemblies may be mated with one another even when the CPA is initially, prematurely placed in its final position since the CPA is permitted to be deflected slightly in the guide ways under a biasing force outward away from the cap housing as the latch member is moved to its engaged position. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    The foregoing summary, as well as the following detailed description of the preferred embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings, embodiments which are present preferred. It should be understood, however, that the present invention is not limited to the precise arrangements and instrumentality shown in the attached drawings.  
         [0014]    [0014]FIG. 1 illustrates an isometric view from a mating end of a plug assembly in accordance with a preferred embodiment of the present invention.  
         [0015]    [0015]FIG. 2 illustrates an isometric view from a back end of the plug assembly in accordance with a preferred embodiment of the present invention.  
         [0016]    [0016]FIG. 3 illustrates an isometric view from a mating end of the cap assembly in accordance with a preferred embodiment of the present invention.  
         [0017]    [0017]FIG. 4 illustrates an isometric view from a back end of the cap assembly in accordance with a preferred embodiment of the present invention.  
         [0018]    [0018]FIG. 5 illustrates an exploded isometric view from the back end of the plug assembly in accordance with a preferred embodiment of the present invention.  
         [0019]    [0019]FIG. 6 illustrates an exploded isometric view from the mating end of the plug assembly in accordance with a preferred embodiment of the present invention.  
         [0020]    [0020]FIG. 7 illustrates an exploded isometric view from the back end of the cap assembly in accordance with a preferred embodiment of the present invention.  
         [0021]    [0021]FIG. 8 illustrates an exploded isometric view from the mating end of the cap assembly in accordance with a preferred embodiment of the present invention.  
         [0022]    [0022]FIG. 9 illustrates a cross-sectional view of the plug assembly in accordance with a preferred embodiment of the present invention.  
         [0023]    [0023]FIG. 10 illustrates a cross-sectional view of the cap assembly in accordance with a preferred embodiment of the present invention.  
         [0024]    [0024]FIG. 11 illustrates an isometric view of a plug terminal position assurance device in accordance with a preferred embodiment of the present invention.  
         [0025]    [0025]FIG. 12 illustrates an enlarged portion of the plug TPA of FIG. 11.  
         [0026]    [0026]FIG. 13 illustrates an isometric view of a plug housing formed in accordance with a preferred embodiment of the present invention.  
         [0027]    [0027]FIG. 14 illustrates an enlarged view of a portion of the plug housing of FIG. 13.  
         [0028]    [0028]FIG. 15 illustrates an isometric view of a plug housing in accordance with a preferred embodiment of the present invention.  
         [0029]    [0029]FIG. 16 illustrates an isometric view of a cap housing in accordance with preferred embodiment of the present invention.  
         [0030]    [0030]FIG. 17 illustrates the bottom of a connector position assurance device formed in accordance with a preferred embodiment of the present invention.  
         [0031]    [0031]FIG. 18 illustrates a bottom isometric view of a CPA formed in accordance with a preferred embodiment of the present invention.  
         [0032]    [0032]FIG. 19 illustrates an isometric view of plug and cap assemblies joined in a filly mated and locked manner in accordance with a preferred embodiment of the present invention.  
         [0033]    [0033]FIG. 20 illustrates a side view of a plug and cap assembly joined in a filly mated and locked position in accordance with a preferred embodiment of a present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0034]    [0034]FIG. 1 illustrates a plug assembly  10  having a front end  12  and rear end  14 . The front end  12  mates with a cap assembly  200  (FIG. 3). The plug assembly  10  includes a latching member  16  formed on one side thereof. The latching member  16  may be formed on the top, bottom or either side wall of the plug assembly  10 . Optionally, more than one latching member  16  may be provided and may be arranged side by side, on opposed walls and the like. The latch member  16  may be formed integrally with the plug assembly  10 . Alternatively, the latch member  16  may be mounted to the plug assembly  10  as a separate unitary structure affixed to the plug assembly  10  in any of several manners, such as through adhesive, glue, snaps, screws and other fastening means. The front end  12  of the plug assembly  10  includes a plug terminal position assurance device (TPA)  18  firmly affixed thereto.  
         [0035]    [0035]FIG. 2 illustrates the plug assembly  10  from the opposite direction, namely with the rear end  14  in full view. The rear end  14  of the plug assembly  10  includes a plug cover seal  22 .  
         [0036]    [0036]FIG. 5 illustrates an exploded view of the plug assembly  10 . The plug assembly  10  is comprised of several components including the plug TPA  18 , a peripheral seal  24 , a plug wire seal  26  and the plug seal cover  22 . The plug assembly  10  further includes a plug housing  28  formed with front and rear sections  30  and  32 . The plug rear section  32  includes rear top, bottom and side walls  34 - 36  that cooperate to define a cavity configured to accept the plug wire seal  26 . The plug cover seal  22  is snapplingly received over the outer edges of the rear top, bottom and side walls  34 - 36 . Latching projections  38  are formed on at least one of the rear top, bottom and side walls  34 - 36  to snappably secure the plug cover seal  22  to the plug housing  28 . The latching projection  38  includes a ramped surface  40  over which a notch cut in an interior surface of the wall of the plug cover seal  22  travels. A rear side of the latching projections  38  include engaging shoulders  42  that securely contact similarly shaped notches in the interior walls of the plug cover seal  22  in order to retain the plug cover seal  22  in an engaged position.  
         [0037]    As shown in FIGS. 1 and 2, vertical supports  44  are mounted on at least one wall of the plug housing  28 . The vertical supports  44  extend upward from the plug housing  28  in a parallel manner. Rear surfaces  46  of the vertical supports include support rods  48  formed therewith and extending in a direction substantially parallel to a longitudinal axis of the plug housing  28 . The support rods  48  are joined at an outer end by a cross bar  50 . An intermediate portion of the cross bar  50  is formed integrally with a latch beam  52  that also extends in a direction substantially parallel to the longitudinal axis of the plug housing and is located between the support rods  48 . The support rods  48  extend from the vertical supports  44  in a direction toward the front end  12  of the plug assembly  10 , while the latch beam  52  extends from the cross bar  50  in an opposite direction toward the rear end  14 . The rear tip of the latch beam  52  includes a decoupling post  54  projecting upward therefrom. The decoupling post  54  includes a chamfered surface  56  and a top surface  58 .  
         [0038]    The plug wire seal  26  (FIG. 5) includes outer rib surfaces  60  sealing the interface between the interior surfaces of the rear top, bottom and side walls  34 - 35  of the housing  28  and the plug cover seal  22 . The plug wire seal  26  further includes an array of wire receiving apertures  62  for receiving wires (not shown). The plug cover seal  22  further includes wire receiving openings  64  aligning with the wire receiving apertures  62  in the plug wire seal  26 . A top side  66  of the plug cover seal  22  includes a slot  68  directed toward and configured to align with a rib  70  formed on the top wall  34  of the plug rear section  32 . The rib  70  and slot  68  cooperate to ensure proper orientation and alignment of the plug cover seal  22  when mounted on the plug rear section  32 .  
         [0039]    The peripheral seal  24  includes inner and outer rib surfaces  72  and  74  forming a sealed connection between an outer peripheral surface of the plug front section  30  and an interior surface of the plug TPA  18 . The peripheral seal  24  is received over the plug front section  30  and is enclosed within the plug TPA  18  when the plug TPA  18  is mounted to the plug housing  28 . The plug TPA  18  includes an outer face plate  76  and top, bottom and side walls  78 ,  80  and  82  (FIG. 1). The face plate  76  includes a plurality of wire receiving openings  84  formed in a desired array corresponding to the configuration of wire receiving apertures  62  and wire receiving openings  64 .  
         [0040]    As shown in FIGS. 5 and 11, the interior surface of the face plate  76  is formed with a plurality of TPA arms  86  mounted thereon and aligned with associated wire receiving openings  84 . Each TPA arm  86  includes an inner wire guide surface  88  formed with an arcuate shape to define a trough extending in a direction substantially parallel to the longitudinal axis of the plug housing  28 . The TPA arms  86  are located along the outer periphery of the wire receiving openings  84 . At least one TPA arm  86  includes a stop wedge  90  and a locking wedge  92  formed along an outer side of the TPA arm  86  (FIGS. 11 and 12). The stop and locking wedges  90  and  92  cooperate with associated features formed on the interior surface of corresponding side walls  95  of the plug front section  30 . As shown in FIGS. 13 and 14, the interior surfaces of the side walls  95  include an outer channel  120  and an inner cutout  93 . The stop wedge  90  and locking wedge  92  engage the outer channel  120  and inner cutout  93  and surround a bridge  121  therebetween to prevent the plug TPA  18  from being entirely removed from the plug housing  28  once the plug TPA  18  is initially inserted. The stop wedge  90 , once engaging the inner cutout  93 , securely retains the plug TPA  18  in a final engaged position corresponding to a position at which the terminals are securely mated to cavity latches (explained below in more detail). The TPA arms  86  include outer fingers  98  that are tapered and received behind the cavity latches in the plug housing  28  only when the terminals are properly inserted into a mated position.  
         [0041]    [0041]FIG. 6 illustrates the plug assembly  10  aligned in an opposite direction with the mating end  12  facing forward. FIG. 6 illustrates in more detail the interior of the plug cover seal  22 . At least one interior surface, such as on the side walls  100  of the plug cover seal  22 , includes a cutout  102  formed to receive the latching projections  38 . A rear wall  104  of the cutout  102  securely engages the shoulder  42  on the latching projection  38 . With reference to the plug housing  28  of FIGS. 6, 13 and  15 , the plug front section  30  includes a cross member  106  extending between the side walls  95 . The cross member  106  includes a plurality of slots  108  cut in upper and lower surfaces of the cross member  106  and configured to align with the wire receiving openings  84  and  64  in the plug TPA  18  and plug cover seal  22 . The slots  108  accept contacts connected to wires extending through the wire receiving openings  84  in the plug TPA  18 . The slots  108  are separated by raised ridge sections  124  that separate the wires housed within the plug assembly  10 .  
         [0042]    [0042]FIG. 9 illustrates a cross sectional view of the plug housing  28  taken along the line  9 - 9  in FIG. 1. As shown in FIGS. 9 and 15, the plug housing  28  includes a plurality of terminal latches  110  formed integrally with the interior surfaces of top and bottom walls  94  and  96  of the plug front section  30 . The terminal latches  110  may be formed with an arcuate inner surface  111  (FIG. 15) extending in a direction parallel to the longitudinal axis of the plug housing  28 . The arcuate surface  111  is contoured to receive the terminal wires inserted into the plug housing  28 . Each terminal latch  110  includes a forked projection  112  directed inward and having the arcuate inner surface  111  shaped to grasp the contour of a terminal wire. The terminal latches  110  are deflectable from a non-engaged position to a bias position in which the terminal latches  110  engage the terminal wires. A latch cavity  114  is formed behind each terminal latch  110  and cooperates to receive a corresponding finger  98  on a TPA arm  86  when the plug TPA  18  is fully inserted to a terminal engaging position. Once the arms  98  are inserted into the latch cavities  114 , the forked projections  112  on the terminal latches  110  securely engage the terminal wires and prevent the wires from being inadvertently pulled from the plug housing  28 .  
         [0043]    As shown in FIG. 15, at least one side wall  95  of the plug front section  30  includes a plug keying notch  116  extending from the front end  12  rearward along the outer surface of the side wall  95 . The plug keying notch  116  cooperates with a projecting rail  118  (FIG. 11) extending along the interior surface of a corresponding side wall  82  of the plug TPA  18 . The rail  118  and plug keying notch  116  cooperate to ensure proper orientation and alignment between the plug TPA  18  and the plug housing  28 .  
         [0044]    [0044]FIG. 15 illustrates that the inner surfaces of the side walls  95  of the plug front section  30  include outer channels  120  cut therein as discussed above. A bridge  121  behind the outer channel  120  cooperates with the stop and locking wedges  90  and  92  formed on the outer sides of the outer TPA arms  86 . The bridges  121  include shoulders  122  having ramped inner and outer surfaces to engage the stop and locking wedges  90  and  92  in order to retain the plug TPA  18  in an initial terminal disengaged position (when the shoulders  122  are located between the stop and locking wedges  90  and  92 ), and a terminal engaged position (when the shoulders  122  are located behind the locking projections  92 .  
         [0045]    Next, the cap assembly  200  will be described in more detail. As shown in FIGS. 3 and 4, the cap assembly  200  includes a front end  212  and a rear end  214 . The front end  212  matingly receives the front end  12  of the plug assembly  10 . As shown in FIGS. 7 and 8, the cap assembly  200  comprises a cap TPA  218 , a cap wire seal  226  and a cap housing  228 . The cap housing  228  includes top, bottom and side walls  234236 . The cap housing  228  includes a cap front section  230  and a cap rear section  232 . The interior surfaces of the top, bottom and side walls  234 - 236  proximate the cap rear section  232  define a cavity adapted to receive the cap wire seal  226 . The cap wire seal  226  includes a plurality of outer ribbed surfaces  260  that form a seal with the interior of the walls  234 - 236  on the cap housing  228 . The cap wire seal  226  includes a plurality of wire receiving apertures  262  that align with wire receiving openings  264  in the face plate  265  on the cap cover seal  222 .  
         [0046]    A top side  266  of the cap wire seal  222  includes a slot  268  that aligns with a rib  270  on the top wall  234  of the rear section  232  of the cap housing  228 . The slot  268  and rib  270  cooperate to ensure proper orientation of the cap cover seal  222 . As shown in FIGS. 7, 8 and  16 , opposite side walls  236  on the cap housing  228  include latching projections  238  having ramped surfaces  240  and engaging shoulders  242 . The latching projections  238  are received within cutouts  202  in the interior surfaces of side walls  201  of the cap cover seal  222 . The cutouts  202  include rear walls  204  that engage the shoulders  242  on latching projections  238  to retain the cap cover seal  222  in an engaged position.  
         [0047]    As shown in FIGS. 7, 8 and  16 , the top wall  234  of the cap housing  228  includes a pair of guide rails  244  extending parallel to one another along a direction substantially perpendicular to a longitudinal axis of the cap housing  228 . The guide rails  244  are located proximate opposite sides of the top wall  234 . The guide rails  244  include guide ways  246  cut therein along opposed interior surfaces of the guide rails  244 . The guide ways  246  extend along a length of the guide rails  244 . At least one guide rail  244  includes a flared ledge  248  aligned with a bottom surface of the guide way  246 . The ledge  248  includes ramped forward and rear edges  250  and  252  (FIG. 16). An interior side of the guide rail  244  further includes a projection  254  located forward of the flared ledge  248  and having a ramped surface and a stop edge.  
         [0048]    The top wall  234  includes a CPA latch  256  (FIGS. 8) having a ramped surface  258  and a locking edge  259 . The CPA latch  256  is oriented with the ramped surface  258  directed toward the rear end  214  of the cap assembly  200  and with the locking edge  259  facing toward the front end  212  of the cap assembly  200 . The top wall  234  further includes a pair of latching projections  272  spaced apart from one another and directed toward the rear end  214  of the cap assembly  200 . The latching projections  272  include ramped surfaces  274  (FIG. 16) directed toward the front end  212  and stop edges  276  directed toward the rear end  214 .  
         [0049]    FIGS.  3 - 4 ,  7 - 8  and  17 - 18 , further illustrate a connector position assurance device (CPA)  300  having a rectangular shaped base  302  with a raised portion  304  extending along one end of the base  302 . The raised portion  304  includes ramped surfaces extending along either side thereof and including ridges to afford better engagement by a user when the user moves the CPA  300  between engaged and disengaged positions. The CPA  300  further includes a pair of flanges  306  extending along either side thereof and directed outward from the base  302 . Optionally, the base  302 , raised portion  304  and flanges  306  may be formed integral with one another. The flanges  306  are configured to be received within the guide ways  246  in the guide rails  244 . The guide ways  246  and flanges  306  cooperate to permit the CPA  300  to slide relative to the cap housing  228  between engaged and disengaged positions.  
         [0050]    When in a disengaged position, the CPA  300  is retained upon the cap housing  228  separate and apart from the plug housing  28 . A bottom surface of the CPA base  302  includes a cross-bar  308  extending downward from the base  302  and formed integrally with the base  302 . The cross bar  308  may be located at an intermediate point along the length of the base  302  and aligned to extend across a width of the base  302 . The cross bar  308  includes a pair of latching beams  310  projecting forward therefrom toward the rear edge  312  of the base  302 . Outer ends of the latching beams  310  include projections  314  extending outward therefrom and having ramped leading edge surfaces and latching rear surfaces  315 . The latching rear surfaces  315  on projections  314  engage the notched rear edges  252  of the flared ledge  248  to secure the CPA  300  in an engaged position. While in the engaged position, the cross bar  308  on the CPA  300  abuts against the locking edge  259  on the CPA latch  256  to prevent the CPA from being removed from the guide rails  244 .  
         [0051]    As illustrated in FIGS. 3 and 4, the CPA  300  is inserted into the guide rails  244  from the rear end  214  in a direction denoted by arrow A. As the CPA  300  is inserted into the guide rails  244 , the cross bar  308  rides over the ramped surface  258  on the CPA latch  256  until the backside of the cross bar  308  engages the locking edge  259  of the CPA latch  256  (see FIG. 4). FIGS. 3 and 4 illustrate the CPA  300  while in its initial disengaged position, yet retained on the cap assembly  200 . As illustrated in FIGS. 3 and 4, both flanges  306  of the CPA  300  are substantially enclosed by the guide rails  244 . When the cap assembly  200  and the plug assembly  10  are mated in a final position, the CPA  300  is moved further in the direction indicated by arrow A to a final engaged position, at which the CPA  300  engages the latch member  16 . When in the final position, the CPA  300  is moved in a direction indicated by arrow A substantially parallel to the longitudinal axis of the cap assembly  200  to a position at which portions of the flanges  306  of the CPA  300  are exposed from and project out of the guide rails  244 . Extending the CPA  300  until the flanges project beyond the edges of the guide rails  244  when in an engaged position enables easier visual confirmation that the CPA  300  is in its final engaged position and that the plug assembly  10  and cap assembly  200  are properly mated.  
         [0052]    As the CPA  300  moves to its final engaged position (FIGS. 18 and 19), the latching beams  310  are biased inward toward one another to permit the projections  314  (FIG. 4) to move inward to ride over the rear edges  252  on the flared ledges  248  (FIG. 16). The latching beams  310  ride along the flared ledges  248  until the projections  314  clear the flared ledges  248  and the rear edges on projections  314  engage the forward edges on the flared ledges  248 . The projections  254  engage the front surfaces of the projections  314  to prevent the CPA  300  from moving to far forward in the direction of arrow A.  
         [0053]    During a latching operation, the plug assembly  10  and cap assembly  200  are aligned such that the front end  12  and plug TPA  18  are received within the opening in the front end  212  of the cap assembly  200 . The plug assembly  10  is forced into the cap assembly  200  until the outer end of the latching member  16  engages the latching projections  272 . As the plug assembly  10  is further inserted, the cross bar  50  on the latching member  16  is biased upward and slid along the ramped surfaces  274 , thereby biasing the support rods  48  and latch beam  52  upward. The cross bar  50  is moved over the latching projections  272  until the inner surface of the cross bar  50  engages the stop edges  276 . Hence the latching projections  272  are retained under the latch beam  52  against the cross bar  50 , while the support rods  48  lie directly against the top wall  234  of the cap housing  228 .  
         [0054]    Once the cross bar  50  snaps over the latching projections  272  (FIGS. 19 and 20), the support rods  48  and latch beam  52  are deflected into a position substantially in line with the channel  316  extending along the bottom of the base  302  and between the flanges  306 . The width of the channel  316  corresponds to the width of the latch beam  52 . Hence, when the CPA  300  is moved in the direction of arrow A to the engaged position (at which the CPA  300  partially extends beyond the ends of the guide rails  244 ), the flanges  306  run along the top surfaces of the support rods  48  and the channel  316  receives the outer portion of the latch beam  52 . Front end portion  318  of the channel  316  and flanges  306  engage and retain the outer end of the support rods  48  and latch beam  52  downward against the top wall  234  of the cap housing  228 . Rear portion  320  (FIG. 19) of the flanges  306  remain within the guide rails  244 , thereby preventing the CPA  300  from being deflected upward away from the top wall  234  of the cap housing  228 .  
         [0055]    The channel  316  and flanges  306  are configured such that the CPA  300  is unable to move to its engaged position during assembly of a plug assembly  10  and cap assembly  200 , unless and until the latching member  16  is received over the latch projections  272 . The post  54  on the rear end of the latch beam  52  enables the latch member  16  to be disconnected from the cap assembly  200 . To disconnect the latch member  16 , the post  54  is pressed downward, thereby prying the support rods  48  upward and the cross bar  50  upward over the latching projections  272 .  
         [0056]    The CPA  300  is configured to permit the plug assembly  10  to be inserted into the cap assembly  200  even when the CPA  300  is prematurely moved to its final engaged position. The base  302  includes a chamfered edge  315  along the front edge  317  below the raised portion  304  to guide the latch beam  52  into the channel  316 . When the CPA  300  is prematurely moved to its final latching position, the cross bar  50  engages the chamfered edge  315  and is guided into the channel  316 . As the latch member  16  is moved to its latched position and is deflected upward over the latching projections  272 , the front end portion  318  of the CPA  300  is deflected slightly upward. The flanges  306  fit in the guide rails  244  with a slight tolerance to permit the front end  318  of the CPA  300  to be deflected upward as the latching member  16  is moved to its engaged position. Once in the engaged position, the latch member  16  is deflected downward and the biasing force applied by the guide rails  244  to the CPA  300  biases the front end portion  318  of the CPA  300  downward as well.  
         [0057]    With reference to FIG. 8, the cap TPA  218  includes a front plate  280  with a plurality of wire receiving openings  282  therein. The front plate  280  further includes a keying post  284  extending outward from the cap TPA  218 . The keying post  283  aligns with a keying opening  83  (FIG. 1) in the plug TPA  18 . The keying post  283  and keying opening  83  cooperate to ensure proper orientation of the plug and cap assemblies  10  and  200 . Optionally, different keying post and opening combinations  283  and  83  may be used with different types of plugs and caps to ensure that, in an application including multiple plugs and caps located in a common area of a system, each plug is connected to the correct associated cap. By providing the keying feature offered by post  283  and opening  83  on the cap TPA  218  and plug TPA  18 , keying feature capabilities are afforded without enlarging the overall envelope of the plug and cap assemblies  10  and  200  which might otherwise be increased if keying features were provided around the parameter of the plug assembly  10  and/or cap assembly  200 .  
         [0058]    As illustrated in FIG. 7, the cap TPA  218  includes a plurality of TPA arms  286  formed on the interior surface of the front plate  280 . Each TPA arm  286  includes a finger  288  extending outward therefrom. Optionally, the TPA arms  286  located nearest the side walls  295  may include stop wedges and locking wedges (not illustrated) similar to those described above in connection with the plug TPA  18 . The stop wedges and locking wedges on TPA arms  286  engage similar structures formed on the interior of the cap housing  228  to retain the cap TPA  218  in an initial position and then in an engaged position.  
         [0059]    [0059]FIG. 10 illustrates a cross sectional view taken along line  10 - 10  in FIG. 3. The top and bottom walls  294  and  296  on the TPA housing  228  include terminal latches  290  formed integrally therewith and extending inward at an angle toward the front end  212 . The terminal latches  290  resemble terminal latches  110  discussed above. The terminal latches  290  include forked projections  292  on the outer ends thereof and have arcuate shaped cutouts therein to receive the terminal wires. Latch cavities  298  are provided between the terminal latches and the top and bottom walls  294  and  296 .  
         [0060]    As shown in FIG. 16, the cap assembly  200  includes an interior shell  350  formed integrally with the cap housing  228 . The interior shell  350  is configured substantially similar to the plug front section  30  discussed above in connection with FIG. 15. In particular, the interior shell  350  includes top, bottom and side walls  352354 . The side walls  354  are connected through a cross member  356 . The cross member  356  includes a plurality of slots  358  configured to receive the terminal wires. The slots  358  are separated with ridged sections  360 . The slots  358  open upward and downward from the cross member  356 .  
         [0061]    Once the terminal wires are inserted into the cap housing  228 , the cap TPA  218  is inserted through the front end  212  until the top, bottom and side walls of the cap CPA  218  are received within an outer groove  362  surrounding the interior shell  350 . The cap TPA is further inserted in the direction of arrow B (FIG. 10) until the fingers  288  on the TPA arms  286  are securely received within the latch cavities  298  and bias the terminal latches  290  inward against the terminal wires.  
         [0062]    Optionally, the latch member  16 , CPA  300  and associated features and structure may be provided on the bottom or sides of the plug assembly  10  and cap assembly  200 , respectively.  
         [0063]    While particular elements, embodiments and applications of the present invention have been shown and described, it will be understood, of course, that the invention is not limited thereto since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. It is therefore contemplated by the appended claims to cover such modifications as incorporate those features which come within the spirit and scope of the invention.