Abstract:
A backshell for an electrical connector gives the electrical connector handedness to force a particular orientation of the connector with respect to a device in order to limit the choice of devices to which the electrical connector can be attached. The backshell fits around the connector and a portion of a cable connected to the connector. The cable is forced into a right angle turn in the interior of the backshell to give the device handedness.

Description:
RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 60/135,371 filed May 21, 1999, which application is incorporated herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an electrical connector assemblies for cables in motor vehicle electrical harnesses and more particularly to a backshell for fitting to end electrical connector for a cable which forces a preferred orientation of the electrical connector assembly relative to a device before connection can be made. 
     2. Description of the Prior Art 
     Harness and electrical cable connector assemblies are well known in the art. A motor vehicle electrical harness provides routing for electrical cables which transmit electrical power and control signals to diverse electrical and electronic devices positioned on a motor vehicle. Individual branches of the harness bundle cables and wires which service components in adjacent sections of a vehicle. A harness includes several large diameter cables enclosing smaller cables and wires inside a sheath. The sheath is typically constructed by winding a tape in a spiral fashion. Wires and cables in a harness are cut to predetermined lengths during manufacture of the harness and the ends of the wires and cables project from under the sheath at appropriate locations for connection to devices. During vehicle assembly workers can lay the harness along a predetermined path on the vehicle and the ends of the appropriate wires and cables to connect to vehicle accessories will automatically be positioned for attachment to devices. This saves considerable time during assembly and reduces the risk of connecting wires and cables to the wrong devices. 
     While the risk of incorrect connection of cables to devices is reduced by precutting the length of wires and cables, it is not eliminated in all cases. Wires and cables for automotive, and other applications, are typically terminated in a standardized connector, suitable for plug attachment to motors, sensors, switches and other devices. The Packard Electric Systems Division of Delphi Automotive Systems in Warren, Ohio, supplies the Metri-Pack connection systems, a family including at least five series of standardized terminators, designed to assure good seating and force correct orientation of the connector to device terminal. 
     Unfortunately, more than one device taking identical connectors may be in close proximity to one another on a vehicle, raising the possibility that two cables having identical connectors may emerge from a harness cord in close proximity to one another. Such an error would be easy to detect were, for example, control cables for a brake actuator and a vehicle horn crossed. Upon first depression of the brake pedal the horn would then sound. More serious, and more likely to occur, is the possibility that control cables leading to devices having similar functions might be crossed. 
     For example, in an anti-lock braking system (ABS) each brake is independently actuated in response to detection of skidding by the wheel associated with that brake. Brake actuation is controlled by a brake modulator valve. Due to space constraints and the lack of suitable mounting locations for the modulator valve, the valves for wheels on each end of a given axle, particularly the front steering axle, are often located in close physical proximity to one another. The electrical connecting cables for the modulators will then emerge from the harness in close physical proximity to one another, allowing the assembly worker or repair technician to cross the leads, which appear identical to one another. If the leads are crossed, indication of a skidding right wheel produces braking modulation for the left wheel and indication of a skidding left wheel produces braking modulation for the right wheel. The results can be difficult to detect in the field and, in an emergency, adverse to control of the vehicle. 
     SUMMARY OF THE INVENTION 
     The invention provides an electrical connector including an electrical cable connected to a terminal connector. The terminal connector is fabricated from a thermoplastic body and has an orientation guide on an exterior surface, A backshell is provided for fitting around the terminal connector and a portion of the cable adjacent to the terminal connector, The backshell comprises a first halfshell and a second halfshell connected on a hinge. The first and second halfshells form, when closed on one another, an interior channel accessible from the outside at two ends for receiving the electrical cable and the terminal connector, respectively. The first and second halfshells form, at the end for receiving the electrical cable, an opening shaped to fit around the cable circumference and further form, at the end for receiving the terminal connector, an opening shaped to fit around the terminal connector. The portion of the opening formed by the first halfshell fits around the orientation guide to force the backshell to assume a particular orientation on the terminal connector and electrical cable. The interior channel defines a turn, which combined with the forced orientation of the backshell, gives the electrical connector handedness. Depending on the direction of the turn, the electrical connector exhibits right or left handedness. Handedness prevents the wire or cable from being twisted to correctly orient the terminal connector to the device and still reach an Incorrect device accepting the terminal connector type. 
     Additional effects, features and advantages will be apparent in the written description that follows. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a perspective view a section of a vehicle frame and front wheel skid monitoring system; 
     FIG. 2 is a front elevation of the vehicle frame of FIG. 1 viewed from the direction of letter “A”; 
     FIG. 3A is a perspective view of an opened backshell in conformance with the present invention; 
     FIG. 3B is a top plan view of an opened backshell in conformance with the present invention; 
     FIG. 3C is a side elevation of an opened backshell in conformance with the present  30  invention; 
     FIGS. 4A-B are end views showing the cable and terminal connector openings, respectively, formed by a closed backshell; 
     FIGS. 5A-B are top and bottom plan views of a right handed electrical connector of the present invention; 
     FIGS. 6A-B are top and bottom plan views of a left handed electrical connector of the present invention; and 
     FIG. 7 is a plan view of an opened backshell. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the figures and in particular to FIG. 1, a preferred embodiment of the invention and its use will be described. In FIG. 1 a motor vehicle frame  10  includes left side and right side frame rails  12  and  14 . Frame rails  12  and  14  are held parallel to one another by a cross member  16  which is located substantially adjacent the front end (indicated by the letter “A”) of frame  10 . Outboard from frame rails  12  and  14  are a left side wheel speed sensor assembly  18  and a right side wheel speed sensor assembly  20 , respectively. Each of wheel speed sensor assemblies  18  and  20  is connected to an onboard computer (not shown) by monitor wires,  22  and  24 , respectively, which emerge from harness  26  along the left and right frame rails  12  and  14 . Left and right side wheel speed sensor assemblies  18  and  20  are components in a antilock braking system (ABS) used to detect wheel skidding. Anti-lock braking systems provide modulation of braking action in response to skid detection. 
     Brake action modulation is provided by a right side ABS modulator valve  30  and a left side ABS modulator valve  28 , both of which are electrically actuated. ABS modulator valves  30  and  28  are located on cross member  16  at the front of the vehicle. The ABS modulator valves  30  and  28  are connected to brake actuators  34  and  38 , respectively, by pressure lines  32  and  36 , which in turn deliver hydraulic fluid to and from the actuators at pressures controlled by the ABS modulator valves. 
     FIG. 2 further illustrates the positioning of ABS modulator valves  30  and  28  and the connection of the valves to the vehicle electrical harness  26 , which is representative of a common configuration found on trucks. Harness  26  is positioned along cross member  16  passing above ABS modulator valves  30  and  28 . Electrical attachment from harness  26  to ABS modulator valves  30  and  28  is had by cables emerging from harness  26 , sections  40  and  44  of which are visible. Cable section  40  is connected to an electrical connector  42  which in turn plugs into a suitable mating slot  47  on ABS modulator valve  30 . Cable section  44  connects to a electrical connector  46  which in turn plugs into a mating slot  49  on ABS modulator valve  28 . 
     FIGS. 3A-C illustrate an embodiment of a backshell  48  used to construct an electrical connector assembly  42 . Backshells, in accordance with the invention, can be applied around the junction of a cable and terminal connector to give the assembly of backshell, cable and terminal connector left handedness or right handedness. The designation of a particular assembly as left handed or right handed is arbitrary, indicating mirror image configurations of otherwise identical devices. In a preferred application, right handedness will be applied to a electrical connector assembly  42  intended for use with an ABS brake modulator  30  installed on the front end of the right side of a vehicle as viewed from the front. In other words, the driver&#39;s side of the vehicle for conventional North American and continental European motor vehicles. Right handedness is indicated on an exterior surface of half backshell  50  by the indicia “A”  67 . It should be understood that a right handed electrical connector assembly  42  may be installed on the opposite vehicle side for wheels towards the rear of the vehicle. 
     Backshell  48  is preferably molded from a heat and oil resistant thermoplastic. Backshell  48  comprises two half backshells  50  and  52 . Top and bottom half backshells  50  and  52  are linked along adjoining major edges by a hinge  58 , on which the half backshells can be folded together. Reference to the half backshells as being “top” and “bottom” is by arbitrary convention. When folded together the half backshells  50  and  52  snap together by the interaction of a plurality of catches  54  and spring loaded latch bars  56  spaced along the unhinged edges of the half backshells. Spring loaded latch bars  56  are “J” shaped appendages arranged vertically along the edges of bottom half backshell  52  to engage latches  54  located symmetrically to the latch bars  56  along the edges of top half backshell  50 . Backshell  48  is opened at ends canted 90 degrees from one another to admit an electrical cable  40  and a terminal connector  47 . An opening for a cable, for example, is defined by semicircular openings  88  and  90  in end wall  84  and  85 , respectively. 
     FIGS. 4A-B illustrate a backshell  48  formed upon closure of top and bottom half backshells  50  and  52 , and more particularly, openings  60  and  62  which are formed to admit and retain a cable and an electrical terminator, respectively. Opening  60  is a circular opening which fits snugly around the circumference of a cable. Opening  62  has a substantially rectangular section, closed at each end by semi-circular walls. A notch  72  is formed inwardly from the edge of top half backshell  50  until it abuts a retaining ridge  80 . A similar retaining ridge  82  is formed parallel to ridge  80 , recessed from the outer edge of the bottom half backshell  52 . 
     FIGS. 5A-B illustrate a right handed electrical connector  42 , comprising a backshell  48 , a section of cable  40  and terminal connector  47 . Cable  40  extends from backshell  48  substantially perpendicular to and coplainer with terminal connector  47 . Guide and connection assurance member  70  project outwardly from terminal connector  47  and aligned with notch  72 . In order to position terminal connector  47  in opening  62 , and align cooperating indentations in the connector with retaining members  80  and  82  (See FIG.  7 ), the guide and connection assurance member must be positioned in notch  72 , which forces a particular orientation of terminal connector  47  in opening  62 . On insertion of electrical connector  42  into a cooperating female connecting slot, circumferential sealing lips  68  help seal the connection against the infiltration of dust and oil. 
     FIGS. 6A-B illustrate a left handed electrical connector  46 , comprising a backshell  51 , a section of cable  44  and terminal connector  49 . Left handedness is indicated by the symbol “B”  67  on the exterior surface of top half backshell  63 . Terminal connector  49  is physically identical to terminal connector  47  of FIG.  5 . Cable  44  extends from backshell  51  substantially perpendicular to and coplainer with terminal connector  49 . Guide and connection assurance member  70  project outwardly from terminal connector  49  and aligned with notch  74 . In order to position terminal connector  49  in the opening from backshell, the guide and connection assurance member  70  must be positioned in notch  74 , which forces a particular orientation of terminal connector  49 , mirroring that obtained for the right handed electrical connector  42 . 
     FIG. 7 an interior channel defined by half backshells  50  and  52  for right handed backshell  48 . Upon folding of the half backshells  50  and  52 , an interior channel is defined by recessed interior surfaces  76  and  78 , respectively, of half backshells  50  and  52 . Retaining members  80  and  82  extend inwardly from the recessed interior surfaces  76  and  78 . Retaining member  80  defines, along one edge, the rearward edge of notch  72 . A cable inserted in backshell  48  is held in two annular openings, defined by semicircular notches  88 ,  89 ,  90  and  91 , which are set in end walls  84 ,  86 ,  85  and  87 , respectively. The interior channel defined by halfshells  50  and  52  forces a right turn in the cable, or individual wires extending from the cable, before attachment to a terminal connector. 
     Utilizing the present invention, otherwise identical electrical connectors, particularly those in close proximity to one another on a motor vehicle, may be differentiated by converting the connectors into mirror images of each other. Doing so reduces the danger of misconnection of the connectors to receptacles, particularly by field technicians working on an unfamiliar vehicle. 
     While the invention is shown in only one of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit and scope of the invention.