Patent Publication Number: US-6338644-B1

Title: Sealed multiple-contact electrical connector

Description:
RELATED APPLICATION 
     This application is related to U.S. application Ser. No. 08/948,340, filed Oct. 9, 1997, now U.S. Pat. No. 6,048,224, issued Apr. 11, 2000, which is commonly owned herewith and hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to electrical connectors, and more particularly to vehicle mounted, environmentally protected exterior connectors which are substantially sealed from the elements. 
     Motor vehicles are often outfitted with an exterior multiple-conductor electric cable and associated connector or outlet to facilitate the towing of general purpose trailers, other motor vehicles, recreational vehicles, trailerable homes, or the like. One of the requirements of towing the trailers or vehicles is that, depending upon the configuration of the trailer or vehicle being towed, electrical signals to energize brake lights, running lights, turn signal lights, and provide power for various accessory devices must be transmitted from the towing vehicle to the towed trailer or vehicle. To accomplish this, electrical conductors which are typically housed in a sheath as a cable are routed to the rear of the vehicle and terminate at a connector mounted at or below the rear bumper of the towing vehicle. The connector has an internal contact configuration which is typically a standard throughout the industry to facilitate the connecting of an oppositely configured connector and associated cable which is part of the towed vehicle or trailer. 
     The externally mounted connector of the towing vehicle is typically mounted at or below rear bumper level, and is therefore subject to substantial environmental exposure which includes water, dust, snow, road salts, and the like. Such environmental exposure tends to corrode, short-circuit, and otherwise degrade the conductivity of electrical connections and thus diminish the operational capability of the connector. Prolonged environmental exposure can even result in the failure of the electrical connection, thus interrupting the electrical power and signals being transmitted to the towed trailer or vehicle. The disruption of signals and power to functions such as brake lights, signal lights etc., poses a serious safety concern to the operator of the vehicle and other motorists, and the provision of effective environmentally protected connectors has posed a problem for the manufacturers as well as users of such connectors. 
     The industry and using public have a need for a cable-connector combination which will reliably deliver electrical signals and electric power to a towed vehicle or trailer when used in the typical environmental conditions of road travel has long-term reliability, and which nonetheless is comparatively easy and economical to manufacture with consistent quality. 
     SUMMARY OF THE INVENTION 
     One aspect of the present invention is an environmentally protected connector of a sealed or substantially sealed character for attachment to a cable having a plurality of electrical conductors where each conductor is terminated at an end thereof with a contact. The connector includes a housing having a floor with a plurality of apertures therethrough arranged in a predetermined pattern. A backshell extends from the floor of the housing and encompasses the extended axes of the apertures, the backshell preferably having at least one bead portion protruding from an outer surface of the backshell and extending at least partially around the backshell. A plurality of electrical contacts are disposed within the housing, each of the electrical contacts having a portion extending through one of the apertures and adapted to mate with one of the contact-terminated electrical conductors. Each of the electrical contacts has a locking member for retaining the electrical contacts in a fixed relationship to the floor. An overmold extends from and is molded annularly about an extended portion of the backshell, a portion of the overmold extending over and engaging the bead. The overmold is also adapted to encompass the outer sheath or exterior of the cable of electrical conductors. 
     Another aspect of the invention is a connector shell for attachment to a cable having a plurality of electrical conductors. The connector shell includes a housing having a floor which has a plurality of apertures therethrough, arranged in a predetermined pattern where the apertures are adapted to receive electrical contacts therethrough. A backshell extends from the floor of the housing and encompasses the extended axes of all of the apertures and has at least one bead portion protruding from an outer surface. The bead extends at least partially around the outer surface. An overmold extends from and is molded about an exterior of the backshell to couple the overmold and backshell together. A portion of the overmold engages the bead portion in a retaining relationship to augment the connection between the overmold and the backshell. The overmold is adapted to encompass an exterior portion of the cable of electrical conductors. 
     Yet another aspect of the invention is an environmentally protected connector for attachment to a cable having a plurality of electrical conductors where each conductor is terminated at an end thereof with a contact. The connector includes a housing having a floor and walls with an upper edge where the walls define a central cavity. The upper edge defines an opening to the cavity, and a flange extends laterally from the walls proximate to the upper edge. The floor has a plurality of apertures therethrough in a predetermined pattern. A cover encloses the cavity opening and is pivotally mounted to the flange. An edge of the cover defines a circular recess about a periphery of the cover. A biasing member cooperates with the flange and the cover to bias the cover toward a closed position. A resilient member retained within the recess is biased against the upper edge when the cover is in the biased-closed position. A backshell extends from the floor of the housing and encompasses the extended axes of the apertures. The backshell has at least one bead portion protruding from an outer surface and extending at least partially therearound. A plurality of electrical contacts are disposed within the housing, each of the electrical contacts having a portion extending through one of the apertures and mated to one of the electrical conductors. The portion extending through the aperture has a locking tab for retaining its respective contact in a fixed relationship to its corresponding aperture. An overmold extends at least from the bead of the outer backshell to an exterior of the cable encompassing the electrical conductors for insulating and isolating the contacts and the conductors from the environment. 
     Still another aspect of the invention is an environmentally protected connector for attachment to a cable having a plurality of electrical conductors where each conductor is terminated at an end thereof with a contact. The connector includes a housing having a floor and walls with an upper edge where the walls define a central cavity. The upper edge defines an opening to the cavity, and a flange extends laterally from the walls proximate to the upper edge. The floor has a plurality of apertures therethrough in a predetermined pattern. A cover encloses the cavity opening and is pivotally mounted to the flange. An edge of the cover defines a circular recess about a periphery of the cover. A biasing member cooperates with the flange and the cover to bias the cover toward a closed position. A resilient member retained within the recess is biased against the upper edge when the cover is in the biased closed position. A backshell extends from the floor of the housing and encompasses the extended axes of the apertures. The backshell also has at least one bead portion protruding from an outer surface and extends at least partially around the backshell. A plurality of electrical contacts are disposed within the housing. Each of the electrical contacts has a portion extending through one of the apertures and further includes a locking tab for retaining the contact in a fixed relationship to its corresponding aperture. The plurality of electrical conductors are terminated with spade-type contacts which are mateably connected to the contact portions. An overmold is molded onto the backshell and extends at least from the bead of the backshell to the exterior of the cable encompassing the electrical conductors. These and other features, advantages, and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an environmentally sealed connector embodying the present invention, wherein an overmold extends from the backshell of the connector to the conductor cable. 
     FIG. 2 is a front view of the connector shown in FIG. 1, showing the cover and mounting flange. 
     FIG. 3 is a side elevational view of the connector shown in FIG. 1, terminated to the electric cable. 
     FIG. 4 is a rear view of the connector shell showing the apertures in the floor of the connector housing. 
     FIG. 5 is a front view of the connector shown in FIG. 1, with the cover removed and showing the contacts arranged inside the connector cavity. 
     FIG. 6 is an enlarged, fragmentary, cross-sectional view of the connector showing the contacts extending through the housing floor and connected to the conductors of the electrical cable with the overmold extending thereover. 
     FIG. 7 is an enlarged view of the connector backshell area of FIG. 4, showing the ribs extending from the floor of the housing for stabilizing the contacts. 
     FIG. 8 is a fragmentary sectional view taken along the plane VIII—VIII of FIG.  7 . 
     FIG. 9 is an enlarged view of a contact extending through the floor of the housing showing the locking tab holding the contact in a fixed relationship to the housing floor. 
     FIG. 10 is an overhead perspective view showing the lower half of the mold with a completed overmolded connector shown in its molding position. 
     FIG. 11 is an enlarged fragmentary perspective view showing features of the mold half shown in FIG.  10 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the invention as oriented in FIG.  1 . However, it is to be understood that the invention may assume various orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. In addition, the term “sealed” as used herein is used in a relative rather than absolute sense, and should be so understood. 
     Turning to the drawings, FIGS. 1-6 show an environmentally protected, sealed connector  20 , which is one of the preferred embodiments of the present invention, and illustrates its various components. 
     The general configuration of the connector, most easily seen in FIGS. 1 and 3, includes a connector shell  22  which is generally comprised of a housing  23  having a rectilinear flange  26  and cover  52  disposed at one end thereof. In the preferred embodiment, housing  23  and cover  52  are formed from a moldable resin by known molding techniques. In another preferred embodiment, the housing  23  is made of a glass-filled polypropylene for making the housing strong and rigid. Flange  26  has a plurality of holes  28  proximate a periphery of flange  26  and extending therethrough for mounting connector  20  to a vehicle structure (not shown). Flange  26  has a fixed hinge  30  proximate to one edge thereof and in which rotatable hinge portion  54  of cover  52  is pivotally received and affixed thereto using hinge pin  51 . Rotatable hinge portion  54  has a slot  55  therethrough wherein a biasing member  68  is disposed. In the preferred embodiment, biasing member  68  is a coiled torsion spring which is retained in place by hinge pin  51 . Torsion spring  68  has a first free end (not shown) which is disposed in retaining hole  46  (FIG. 5) in flange  26 . A second free end (not shown) of spring  68  bears against cover  52  in such a manner as to bias cover  52  toward a closed position to cover cavity opening  49  (FIG.  5 ). Cover  52  has a thumb tab  56  disposed substantially opposite from rotatable hinge portion  54  to aid a user to overcome the biasing force of spring member  68  to rotate cover  52  to an open position wherein cavity opening  59  is exposed. 
     Housing  23  further includes walls  24  which extend from a floor  34  to form cavity  48  (FIGS.  5  and  6 ). In the preferred embodiment, walls  24  comprise a cannularly configured wall  24 . An overmold  81  extends from the rear side of floor  34  to and over the sheath or outer covering of cable  74 , to environmentally shield the interface of connector shell  22  and wire cable  74 . Although the overmold  81  is shown as having a basically smooth outer surface, the overmold could also have a circumferentially ribbed surface. 
     Referring to FIGS. 3 and 6, cover  52  in the preferred embodiment includes a lip  58  extending rearwardly and around the periphery of cover  52 . Lip  58  in combination with bottom surface  53  of cover  52  defines a recessed portion  60  of cover  52 . A resilient annular member  62  is disposed within recessed portion  60  and is retained therein by retainer  64  which, in turn, is fastened to cover  52  by screw  66 . In use, when cover  52  is moved into its closed position by biasing member  68 , annular lip  58  extends around the outside of the end edge  32  of housing  23  and resilient member  62  bears directly against end edge  32 . In this manner cavity  48  is both shielded and effectively sealed from the environment when connector  20  is not interconnected with a mating plug. In either the open or closed position of cover  52 , an outwardly projecting top flange  21  and side flanges  21 A provide a partial cover or shield for hinge  30  and the entrance to cavity  48 . 
     FIGS. 4-8 disclose additional features of housing  23 . While walls  24  of housing  23  are generally cannularly shaped in the preferred embodiment, a keying slot  50  (FIG. 5) is provided at an upper portion of cannular wall  24 . Keying slot  50  functions to properly align mating terminals of a mating connector (not shown) with contacts  86  and  90  of connector  20  when the mating connector is plugged into the latter in use. Floor  34  has a plurality of apertures  44  therethrough (FIGS. 4,  6 ,  7 , and  9 ) which in the preferred embodiment are rectilinear in shape and have a substantially greater length than width. Apertures  44  are generally arranged in annular fashion about the central axis of cannular wall  24  and may comprise any desired number, a total of six apertures  44  being shown for purposes of illustration. An additional central aperture  42  extends through floor  34  and is disposed near the center of floor  34 . Those skilled in the art will appreciate that this particular geometric arrangement of apertures serves to configure connector  20  in a manner which conforms to an industry standard for connectors utilized to distribute electrical power and signals from a towing vehicle to a towed vehicle or trailer, but other such aperture configurations for alternate connector applications are possible. A central portion  37  of floor  34  may be disposed out of the plane of floor  34  to accommodate electrical contacts of a different configuration than accommodated by apertures  44 , as discussed in greater detail below. 
     In the preferred embodiment, housing  23  has a cannularly shaped outer backshell  36  (FIGS. 4,  6 , and  8 ) extending rearwardly from floor  34  substantially coaxial with cannular wall  24 . Outer backshell  36  has a diameter sufficiently large enough to encompass the extended axes of apertures  42  and  44 . Outer backshell  36  has at least one raised bead portion  40  protruding from an outer surface of the outer backshell  36  and extending circumferentially at least partially around the outer surface of backshell  36  (two axially aligned such bead portions, each extending part way around backshell  36  being shown; FIGS. 2,  4 , and  8 ). The bead portion(s)  40  are preferably barblike like in shape, as shown, but could be more rounded or have other configurations as well. An inner backshell  38  also extends from floor  34  and encompasses central portion  37  of floor  34  and central aperture  42 . Inner backshell  38  functions to isolate aperture  42  and its associated electrical contact  90  received therein from apertures  44  and their associated contacts  86  received therein. 
     As shown in FIGS. 5,  6 , and  9 , electrical contact  90  and a plurality of electrical contacts  86  are inserted through apertures  42  and  44 , respectively, to present an annular array disposed about a central electrical contact  90  for interconnection with a correspondingly arranged mating plug. Those skilled in the art will appreciate that the contact configuration as presented within cavity  48  of housing  23  is necessarily dictated by the contact configuration of the plug to be mated with connector  20 , and vice versa. The portions of the electrical contacts within cavity  48  can be either male or female; however, a male portion  88  of contact  86 , as most clearly seen in FIG. 9, extends through aperture  44  in floor  34 ; similarly, a portion  92  of contact  90  extends through central floor portion  37 . Contact portion  88  is generally in the form of a rectilinear blade which is marginally smaller than aperture  44  to facilitate the extension of portion  88  through aperture  44 . Portion  88  also incorporates a locking member  94  to retain electrical contact  86  in a fixed relationship with floor  34 . In the preferred embodiment, locking member  94  comprises a locking tab which is a cantilevered tab attached at one end to portion  88  having a free end  95  which is displaced out of the plane of portion  88 . As portion  88  is extended through aperture  44 , the sides of aperture  44  flexibly displace cantilevered locking tab  94  to substantially coincide with the plane of portion  88  until free end  95  becomes disposed beyond outer floor surface  35 . When portion  88  is fully extended through floor  34 , free end  95  of locking tab  94  is disposed beyond the plane of outer surface  35  of floor  34 , whereupon free end  95  of locking tab  94  springs back to its normal position out of the plane of portion  88 . Free end  95  is thus disposed marginally outside of aperture  44  and bears against outer surface  35  of floor  34 , thereby preventing the extraction of electrical contact  86  from floor  34  to maintain contact  86  in a fixed relationship to floor  34 . 
     Referring now to FIG. 6, cable  74  has a plurality of electrical wires or conductors  76  housed therein. Each of conductors  76  have a spade-type terminal  78  secured thereto in electrically conductive relation. Spade-type terminals  78  are well-known in the art. Each of conductors  76  terminated with a spade terminal  78  is connected to portion  88  of contact  86  or portion  92  of contact  90  in a female-male fashion thereby providing an electrically conductive path from conductors  76  to contacts  86  and  90 . 
     As noted above and as further shown in FIG. 6, the overmold  81  extends from an outer surface of the outer backshell  36  to an external portion (e.g., outer sheath) of wire cable  74 . Beads  40  of the preferred embodiment (shown in FIGS. 7 and 8) project radially outwardly from the outer surface of the outer backshell  36 . As the overmold  81  is molded onto the outer backshell  36 , the overmold  81  conforms to and fits contiguously around beads  40  (FIG.  6 ), thereby forming an external enlargement  83  (FIG. 3) or  83   a  (FIG.  10 ). With the overmold  81  molded over and closely conforming to the external geometry of the outer backshell  36  and beads  40 , beads  40  function to prevent the inadvertent withdrawal of overmold  81  from the exterior of the outer backshell  36 . The close-fitting nature of the overmold  81  around the outer backshell  36  and the outside of wire cable  74  also functions to firmly and positively connect backshell  36  and cable  74  together, and the flow of molding material into the voids inside cavity  48  isolates contact portions  88 , spade terminals  78  and the adjacent portions of conductors  76  from the environment and from any short-circuiting or the like. The overmold  81  substantially fills all of the adjacent or proximate voids within the outer backshell  36 , inner backshell  38  and cable  74 . The overmold  81  therefore also functions to isolate aperture  42  and its associated electrical contact  90  received therein from apertures  44  and their associated contacts  86  received therein. Preferably, the overmold  81  is a flexible polyvinyl-chloride (PVC) plastic (e.g., durometer 60-70, Shore A) that is injection-molded around the outer backshell  36  of the housing  23  and the outside of the wire cable  74 . Therefore, when the outer cover of cable  74  is made of PVC, the overmold  81  bonds to it to create a strong mechanical attachment and corresponding environmental seal. 
     As shown in FIG. 6, the injected material forming overmold  81  enters the inside of outer backshell  36  and inner backshell  38 , and is present on both sides of the central floor portion  37 , having flowed there during the injection molding process. This seals all voids or gaps between the housing  23  and the terminals  78 . The amount of overmold material  81  flowing into the central floor portion  37  can be controlled by the pressure under which it is forced into the injection mold and by the injection duration, as well as by controlling the viscosity of the overmold material  81  injected into the mold. When the overmold material is injected slowly, it will first surround the cable  74  and the outer backshell  36 , and then enter the outer backshell  36 , the inner backshell  38  and the central floor portion  37 . When the injection parameters of overmold  81  are suitably controlled, the overmold material will only flow into the front part of the central floor portion  37 . The overmold  81  will therefore hold the contact portions  88  in the proper position in the outer backshell  36 , the inner backshell  38  and the housing  24 . 
     FIGS. 7 and 8 illustrate additional preferred features of the backshell area of housing  23 . Since the thickness of floor  34  is relatively small with respect to the length of electrical contacts  86  and portion  88  extending through apertures  44 , there is minimal support for maintaining contacts  86  substantially perpendicular to floor  34 . To provide the required support to maintain contact  86  substantially perpendicular to floor  34 , ribs  96  are provided which extend from floor  34  and are attached to the outer backshell  36 . One or more ribs  96  are disposed at either side of apertures  44  and  42 , with each rib  96  having a rib edge  98  which substantially coincides with a marginal edge of apertures  44  or  42 . Rib edges  98  in combination with the marginal sides of apertures  42  and  44  function to maintain portions  88  and  92  of electrical contacts  86  and  90  substantially perpendicular to floor  34  and thus provide stable, well-positioned contacts  86  and  90  to engage with those of a mating plug (not shown). In the preferred embodiment, two ribs  96  are disposed along each side of each aperture  44  and  42 . The outer backshell  36  and inner backshell  38  may also have radial walls extending radially from the inner backshell  38  to the outer backshell  38  between adjacent apertures  44  in order to protect adjacent contacts  86 . 
     The environmentally protected or sealed connector  20  is preferably made by first molding the connector shell  22  and then pressing the contacts  86  into the slots  44  in the connector shell  22 . The cable  74  is then cut to length, a desired portion of its outer sheath is removed to expose a length of the conductors  76 , and a desired length of the outer insulation of conductors  76  is stripped, whereupon the exposed, individual conductors  76  are secured to terminals  78 . The terminals  78  of the conductors  76  are then engaged with a corresponding contact  86  which has been inserted through the slots  44  of the connector shell  22 . The connector shell  22  and the cable  74  assembly are then placed into the lower half  100  of a vertical, injection mold, as shown in FIG.  10 . The operator of the mold closes the mold to seal around both the connector shell  22  and the cable  74 , thereby creating a pocket from the end of the cable  74 , across the individual conductors  76  and terminals  78  and up into the connector shell  22 . The fluent molding material is then injected into the mold to fill this pocket, and it flows over the outside of cable  74 , over and around the conductors  76 , the terminals  78  and into the central portion  37  of the floor  34  of the connector shell  22  to seal the gap between the connector shell  22  and the terminals  78 . 
     Due to the pressure under which the molding material is forced into all of these areas and their adjacent voids, the molding material should be introduced from a location near the end of mold  100  which is adjacent cable  74 , rather than from a location near the floor  34  (or through the latter, from cavity  48 ), and the molding pressure etc., controlled, since otherwise there may be some resulting disruption of the interconnected spade connectors  78 ,  92  inside backshell  36 . Furthermore, due to the comparatively large volume of the space in the area of the conductors  76  and connectors  78 ,  92 , compared to the space around the outer sheath of cable  74 , the latter area could become only partially filled with molding material before such material begins to set up. To prevent this, the injection mold should have an annular racetrack  102  (FIG. 11) at the end of the pocket  104  nearest cable  74 . The annular racetrack  102  forms an annular bead  75  of the molding material around the circumference of the overmold  81  at an end thereof distal the backshell  36  (FIG.  10 ). The annular racetrack  102  provides a void which improves the flow of the PVC into that part of the injection mold at the onset of injection. While it is desirable (as point out above) to introduce the molding material from a point distal the backshell  36 , without the racetrack  102  the molding material tends to rapidly flow toward the backshell  36 , without first fully encapsulating the cable  74 . This would result in trapped air and an unfilled or insufficiently filled area known as a void in the area of cable  74 . If the molding material is injected at a high pressure in order to eject such trapped air and fill the area otherwise voided, the high pressure may break the contact  86  away from the terminal  78 . The racetrack  102  allows the molding material to surround the cable  74  before flowing up toward the backshell  36 . The preferred PVC overmold material is preferably injected at a pressure of about 500 psi and a temperature of about 370° to about 400° F. The injection mold  100  preferably has ridges  106  around the outside of cable  74  (FIG. 11) for gripping the cable and holding it in place during the injection of the overmold material from the cable toward the backshell. 
     It is to be pointed out once again that while the foregoing disclosure addresses a particular preferred embodiment, and best mode, the particular apparatus described and the various detailed aspects thereof noted are regarded as pertaining to only the most preferred version of the invention and to merely illustrate the principles and concepts involved in the invention, other embodiments, and versions of the invention no doubt being feasible and potentially appropriate in other circumstances. A simple example of one such variation is the smoothly conical shape of overmold  81  shown in FIGS. 1,  3 , and  6 , as contrasted with the circumferentially ribbed version shown in FIG. 10, (which may be considered the preferred embodiment). It should therefore be understood that the foregoing description of a particular preferred embodiment is provided for purposes and illustration, and not as a measure of the invention, whose scope is to be defined solely by reference to the ensuing claims. Embodiments of the invention differing from those set forth above which nonetheless utilize the underlying concepts of the invention and incorporate its spirit should therefore be considered as within the scope of the claims appended below, unless such claims by their language specifically state otherwise.