Patent Publication Number: US-6666726-B2

Title: Electrical connector assembly

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation-in-part of U.S. application Ser. No. 09/919,099, filed Jul. 31, 2001 now U.S. Pat. No. 6,443,778, which claims the benefit of U.S. provisional application Ser. No. 60/221,744, filed Jul. 31, 2000, the teachings of which applications are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates in general to electrical connectors, and in particular to an electrical connector assembly having keyed components for preventing inadvertent connection of a plug with an incorrect receptacle. 
     BACKGROUND 
     Whenever two or more plug and receptacle pairs, each comprising the subassemblies of a connector arrangement, are located adjacent to each other, there is always the possibility that the various connector plugs may not be mated to the receptacles for which they were intended, through human error. This is particularly true where these connections are located in difficult access positions. If the connectors are of the single cable coaxial type, for example, there is nothing about the connector subassemblies (plug and receptacle halves) themselves that would prevent mismating, since the corresponding subassemblies are frequently identical parts. 
     Although some coaxial connectors are “polarized”, these are limited to situations where there are just two coaxial connections to be considered at any one location. Even in multi-pin connectors, any “keying” provided is usually for rational alignment purposes and cannot prevent the inadvertent mismating of identical plug and receptacle connector subassemblies. 
     There is, therefore, a need in the art for electrical connectors that are configured to efficiently and reliably prevent inadvertent connections of a plug into an incorrect receptacle. 
     SUMMARY OF THE INVENTION 
     A connector assembly consistent with the invention includes a plug portion and a receptacle portion. The plug portion includes a coupling nut and a separate key rotatably secured to an interior surface of the coupling nut. The key includes a first flat surface and a projection that extends from an interior surface of the key. The receptacle portion includes an outer shell and threads for meshingly engaging corresponding threads on the plug upon mating of the plug to the receptacle. The outer shell includes a second flat surface and a raceway. The second flat surface is positioned to align with the first flat surface, and the raceway is dimensioned to receive the projection. The projection is maintained in the raceway upon mating of the plug with the receptacle through meshing engagement of the threads on the receptacle with the threads on the plug. 
     In another embodiment, a connector assembly consistent with the invention includes a keyed plug and receptacle. The plug has a coupling nut with at least one plug keying feature at a mating end of the plug. The plug includes a spring configured for biasing the coupling nut away from a mating end of the plug. The receptacle includes threads for meshingly engaging corresponding threads on the plug upon mating of the plug to the receptacle. The receptacle further includes at least one receptacle keying feature at a mating end of the receptacle, the receptacle keying feature being configured to mate with the plug keying feature. Upon mating of the plug with the receptacle, the receptacle and plug keying features mate with the spring biasing the coupling nut away from the receptacle. The spring thus assists in disengaging the keyed connection between the plug and receptacle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     For a better understanding of the present invention, together with other objects, features and advantages, reference should be made to the following detailed description which should be read in conjunction with the following figures wherein like numerals represent like parts: 
     FIG. 1 is a partial sectional view of an exemplary connector assembly consistent with the invention wherein the top portion illustrates an exemplary plug and receptacle consistent with the invention in a mated position and the bottom portion illustrates the plug and receptacle in an unmated position. 
     FIG. 2 is a side view of the exemplary plug illustrated in FIG.  1 . 
     FIG. 3 is an end view of the exemplary plug illustrated in FIG.  1 . 
     FIG. 4 is an end view of the exemplary receptacle illustrated in FIG.  1 . 
     FIG. 5 is a side view of the exemplary receptacle illustrated in FIG.  1 . 
     FIG. 6 is an end view of a key consistent with the invention illustrating alternative key positions. 
     FIGS. 7A-7C are a partial sectional views of a lower half of another exemplary connector assembly consistent with the invention illustrating another exemplary plug and receptacle in successive positions from unmated to mated. 
     FIG. 8 is a side view of the exemplary plug illustrated in FIGS. 7A-7C. 
     FIG. 9 is an end view of the exemplary plug illustrated in FIGS. 7A-7C. 
     FIG. 10 is an end view of the exemplary receptacle illustrated in FIGS. 7A-7C. 
     FIG. 11 is a side view of the exemplary receptacle illustrated in FIGS.  7 A- 7 C. 
    
    
     DETAILED DESCRIPTION 
     The present invention will now be described in connection with exemplary embodiments wherein the receptacle is adapted to mount to an instrument panel, or the like. Those skilled in the art will recognize, however, that the advantages of the invention could be incorporated into many connector designs. It is intended, therefore, that the invention not be limited to the specific embodiments described, but include any variations thereof associated with use in varied connector schemes and designs. 
     In one embodiment of the present invention, there is provided a connector assembly including keyed plug and receptacle portions. The plug includes a retractable coupling nut and a key that rotates relative to the coupling nut to allow threaded connection between the plug and the receptacle. The receptacle is configured to receive the key to prevent inadvertent connection of an incorrect plug with the receptacle. 
     Turning to FIG. 1, a partial sectional view of an exemplary connector assembly  10  consistent with the invention is illustrated, wherein the top portion illustrates an exemplary plug  12  and receptacle  14  consistent with the invention in a mated position and the bottom portion illustrates the plug  12  and receptacle  14  in an unmated position. In the illustrated exemplary embodiment, the plug portion includes a retractable coupling nut  16 , which moves axially against the bias of a spring (not shown). In the top portion of FIG. 1, the coupling nut is shown in an extended position, and in the bottom portion of FIG. 1, the coupling nut is shown in a retracted position. 
     In the illustrated exemplary embodiment, the coupling nut  16  includes internal threads  18  for meshingly engaging corresponding exterior threads  20  on the receptacle portion. The plug also includes a key  22 , which includes a projection  23  that mates with a corresponding raceway  24  in the receptacle to ensure that a plug is mated with an appropriate receptacle. In the illustrated embodiment, the key  22  is held in place on the end of the coupling nut  16  by a retainer ring  26 , but is free to rotate relative to the coupling nut  16 . 
     Electrical connection between a center pin  28  on the plug and a center conductor  30  on the receptacle may be established and maintained by forcing the coupling nut axially outward in the direction of the receptacle  14  and mating projection  23  of the key  22  with the raceway  24  on the receptacle. The interior surface of the key  22  also includes a flat portion  32 . The flat portion  32 , as shown in FIG. 3, is aligned with a corresponding flat portion  34  of an exterior surface of an outer shell  37  of the receptacle, as shown in FIG.  6 . 
     The plug is threaded onto the receptacle via threads  18  and  20 . Mounting of the key  22  to the coupling nut to allow relative rotational movement therebetween allows the projection  23  to remain in the raceway  24  and the flat surface  32  of the key to remain aligned with the flat surface  34  on the receptacle as the coupling nut rotates onto the receptacle with meshing engagement of the threads. To remove the connection, the coupling nut  16  is rotated in an opposite direction, while the key  22  remains in the raceway  24 , until the threads  18  on the coupling nut disengage from the threads  20  on the receptacle. Then, the coupling nut may move rearward with the key  22  traveling axially in the raceway  24  until it is withdrawn therefrom. 
     An exemplary plug consistent with the invention is illustrated in FIGS. 2 and 3, and an exemplary receptacle consistent with the invention is illustrated in FIGS. 4-5. As shown in FIG. 3, the flat surface  32  and the projection  23  of the key  22  define a key angle, measured in this instance from the center of the flat surface  32  to the key  22 . The key angle for the plug  12  is configured to match a corresponding key angle for the receptacle. 
     In the exemplary embodiment illustrated in FIG. 5, the flat surface  34  on the receptacle is formed on the exterior surface of the outer shell  37 . Also, the keyway for receiving the projection  23  is configured as a groove in the outer shell  37 . The receptacle key angle is measured from the center of the flat surface  34  on the receptacle to the center of the raceway  24 . 
     Although in the illustrated exemplary embodiment the projection  23  and the keyway  24  are generally rectangular in cross-section, those skilled in the art will recognize that these elements may be configured in any regular or irregular geometric shape and/or multiple keys and associated keyways may be provided. Also, the keyway need not have the same cross-sectional shape as the projection. In regard to the flat surfaces  32  and  34 , the illustrated embodiment depicts only a single flat surface. It is possible, however, to provide non-flat surfaces and/or multiple flat surfaces or non-flat surfaces. 
     Advantageously, a variety of matching key angles for the plug and receptacle are possible. FIG. 4, for example, is an end view of a key  22   a  consistent with the invention illustrating alternative key angle positions. Each of the alternative key angle positions is measured from the flat surface  32   a  to an associated one or ones of the projections  23   a . The key angle or angles for the key  22   a  would be established by removing material in the key, e.g. to line  29 , to leave a selected one or ones of the projections  23   a  extending radially inward. The corresponding receptacle would be provided with a flat surface positioned to align with the flat surface  32   a  and a number of raceways  24  each of which configured to mate with an associated one of the projections  23   a.    
     There is thus provided a connector assembly including a plug and receptacle that are keyed to one another to prevent inadvertent connection of a plug with an incorrect receptacle, which could cause damage to associated equipment. Consistent with the invention a retractable coupling nut is provided on the plug and threaded engagement of the plug to the receptacle is achieved with a key projection on a rotatable key maintained in a corresponding raceway in the receptacle. The key projection therefore maintains its position in the raceway during mating of the plug to the receptacle to allow facile withdrawal of the key from the raceway when connection between the plug and receptacle is removed. 
     Turning now to FIGS. 7-11, there is illustrated another exemplary embodiment  50  of a connector assembly consistent with the invention. The illustrated embodiment  50  includes keyed plug  52  and receptacle  54  portions. The plug includes a spring-biased coupling nut  56  that is keyed to mate with the corresponding key features on the receptacle to prevent inadvertent connection of an incorrect plug with the receptacle. Advantageously, the coupling nut  56  is spring biased in a direction away from the receptacle  54  to allow facile removal of the keyed connection between the plug and receptacle. 
     FIGS. 7A-7C are partial sectional views of a bottom portion of the assembly  50  successively illustrating the plug  52  and receptacle  54  from unmated to fully mated positions. In particular, FIG. 7A illustrates an unmated position, FIG. 7B illustrates a partially mated position, and FIG. 7C illustrates a fully mated position. Since the top and bottom halves of the assembly are symmetrical in sectional view, the top portion of the assembly has been omitted from the sectional views in FIGS. 7A-7C for clarity. 
     In the illustrated exemplary embodiment, the coupling nut  56  includes internal threads  58  for meshingly engaging corresponding exterior threads  60  on the receptacle portion. With reference also to FIGS. 9,  10 , and  11 , the plug also includes a number of raceways  62  dimensioned for receiving corresponding keying projections  74  on the receptacle to form a keyed relationship between the plug and receptacle. As shown in FIGS. 10 and 11, the projections  72  may be pins extending radially from the body  78  of the plug in locations corresponding to the raceways in the coupling nut. 
     Advantageously, a spring  64  is provided for biasing the coupling nut  56  axially away from the receptacle  54 . The spring is disposed between a shelf  66  and an opposed shelf  68  on the coupling nut. In an unmated position, the spring biases the coupling nut against a stop  80  on the plug, as shown in FIG.  7 A. As will be described in greater detail below, the spring facilitates removal of the keyed connection between the plug and receptacle by biasing the coupling nut away from the receptacle. 
     With specific reference to FIG. 7A, electrical connection between a center pin  70  on the plug and a center conductor  72  on the receptacle is initially made by fitting the coupling nut  56  over the receptacle  54  until the coupling nut abuts the keying projections  74  on the receptacle. The coupling nut  56  is rotated until an indicating mark  90  on the plug is aligned with an indicating mark  92  on the receptacle. With this alignment, the raceways  62  on the plug and the keying projections  74  on the receptacle are aligned. If the arrangement of the raceways  62  on the plug does not match the keying projections  74  on the receptacle, the plug and receptacle do not match and cannot be mated electrically or mechanically. 
     The coupling nut  56  is then forced toward the receptacle  54 , against the bias of the spring  64 , so that the nut moves over and beyond the keying projections  74 , as shown in FIG.  7 B. In this position, the ends of the pins  74  may be disposed in a cavity  82  defined between the coupling nut and the plug. The coupling nut  56  may then be rotated to fully engage the mating threads  58 ,  60  on the plug and receptacle, as shown for example in FIG.  7 C. 
     To remove the connection between the plug and receptacle, the coupling nut  56  is rotated to release the threaded connection. Upon disengagement of the threads  58 ,  60 , the coupling nut will be forced away from the receptacle by the spring  64  to abut the keying projections  74 . Continued rotation of the coupling nut will cause the keying projections  74  and raceways  62  to align and engage. At this point, the spring will force the coupling nut over the keying projections. The plug and receptacle are then restrained only by friction, and can be pulled apart. 
     Those skilled in the art will projections  74  and raceways  62  may be configured in any regular or irregular geometric shape. The projections and raceways can also be reversed in position, i.e. the projections can be placed on the coupling nut and the raceways on the plug. Also, the raceways need not have the same cross-sectional shape as the projections 
     Key angles for the assembly may be defined by the angle from one of the keying projections or raceways to another. FIG. 9, for example, illustrates key angles A and B measured from raceway  62 ′ for the illustrated exemplary plug. To provide a mating receptacle, corresponding angles may be made for the keying projections  74 , as shown in FIG.  10 . Advantageously, a variety of matching key angles for the plug and receptacle are possible. 
     The embodiments that have been described herein, however, are but some of the several which utilize this invention and are set forth here by way of illustration but not of limitation. It is obvious that many other embodiments, which will be readily apparent to those skilled in the art, may be made without departing materially from the spirit and scope of this invention.