Abstract:
The retention system is provided for a threaded member (14, 54) and an electrical connector (10) which includes a sheet metal shield (46) juxtaposed on a dielectric housing (32). A threaded hole (58) is provided in the shield (46) for 4 threadingly receiving the threaded member (14, 54). A hole (64) is provided in the dielectric housing (32) behind the threaded hole (58) in the shield (46) for threadingly receiving the threaded member (14, 54) after the shank 54 of the threaded member (14, 54) passes through the threaded hole (58) in the shield (46). 
     During assembly, the threaded members (14, 15) self thread into interfering portions of the housing (32) defined by the housing holes (64) to thereby increase the resistance of threading in order to prevent stripping of the threaded holes (58) in the shield (46).

Description:
FIELD OF THE INVENTION 
     This invention generally relates to the art of electrical connectors and, particularly, to a retention system between a screw member and a shielded electrical connector. 
     BACKGROUND OF THE INVENTION 
     Very generally, electrical connectors are devices provided for interconnecting electrical circuits. A typical electrical connector includes a dielectric housing, such as of plastic material or the like, in which are mounted a plurality of terminals terminated to the electrical circuits. The circuits may range from discrete electrical wires to circuit traces on a printed circuit board. 
     Often, electrical connectors are provided with some form of shielding to protect or shield the electrical terminals or electrical interface from interference, such as electromagnetic or radio interference, whether the interference comes from outside the connector or the interference radiates from within the connector. Such shielding typically is fabricated of stamped and formed, or drawn sheet metal material. 
     Still further, electrical connectors often have some form of latching or retention system for securing the connector to a complementary mating connector, to a panel, or to a wide variety of other connection devices. Retention systems vary widely and can range from integral latches on the connector to separate threaded or screw members to secure the connector to the mating connector, panel or the like. For instance, one or more &#34;jack screws&#34; are used to directly interconnect a pair of mating connectors. If one of the mating connectors is mounted to a panel, jack screw nuts may be used to mount the connector to the panel, with a mating connector having jack screws for threading into the jack screw nuts. Typically, the jack screw nuts are threaded into internally threaded holes in the sheet metal shield of the connector or into a metal insert within the housing. 
     A problem with using threaded members or screws, such as the aforementioned jack screws or jack screw nuts, is that the internally threaded holes in the sheet metal shield may have a tendency to become stripped during an assembly operation. For instance, an operator may set a power tool, such as a screw or nut driver, at a particular torque which may vary slightly during repetitive cycles, but the variance is sufficient to cause stripping of the internally threaded holes in the shield. Increased resistance could be achieved simply by increasing the thickness of the sheet metal shield, but this would unnecessarily increase the cost of the connector. The present invention is directed to solving these problems with an improved retention system for threaded members in an electrical connector which includes a sheet metal shield. 
     SUMMARY OF THE INVENTION 
     An object, therefore, of the invention is to provide a new and improved electrical connector retention system of the character described. 
     In the exemplary embodiment of the invention, the retention system is adapted for a threaded member or screw in conjunction with an electrical connector which includes a metal shield juxtaposed on a dielectric housing. A threaded hole is provided in the shield for threadingly receiving the threaded member. A hole is provided in the dielectric housing behind the threaded hole in the shield for threadingly receiving the threaded member after the member passes through the threaded hole in the shield. Therefore, additional resistance is provided against stripping of the threaded hole in the shield without increasing the thickness of the shield. 
     As disclosed herein, the dielectric housing of the electrical connector is adapted for mounting a plurality of terminals and includes a flange portion defining a face. The sheet metal shield includes a flange portion juxtaposed generally against the face of the flange portion of the housing. The threaded hole is provided in the flange portion of the shield, and the hole in the housing is provided in the flange portion thereof immediately behind the threaded hole in the shield. 
     Preferably, the connector housing is fabricated of plastic material, and the hole in the plastic housing is orthogonal in cross-section. The hole is tapered from a wider mouth nearer the shield toward a narrower section further from the shield. The hole is also unthreaded. 
    
    
     Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features of this invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with its objects and the advantages thereof, may be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements in the figures and in which: 
     FIG. 1 is an perspective view of a pair of mating connectors just prior to mating, with one of the connectors adapted for use with the retention system of the invention; 
     FIG. 2 is a perspective view of the one connector of FIG. 1 incorporating the retention system; 
     FIG. 3 is an enlarged, fragmented section taken generally along line 3--3 of FIG. 2, in conjunction with a jack screw nut about to be threaded into the connector; 
     FIG. 4 is a fragmented section taken generally along line 4--4 of FIG. 3; 
     FIG. 5 is a view similar to that of FIG. 3, with the jack screw nut threaded into the internally threaded hole in the shield; 
     FIG. 6 is a view similar to that of FIGS. 3 and 5, with the jack screw nut fully threaded into both the hole in the shield and the hole in the dielectric housing; 
     FIG. 7 is a fragmented section view similar to that of FIG. 4 but of an alternate design; and 
     FIG. 8 is a fragmented section view similar to that of FIG. 4 but of still another alternate design. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings in greater detail, and first to FIG. 1, a first electrical connector, generally designated 10, is secured to a panel 12 by a pair of jack screw nuts 14. The nuts have internally threaded holes 16. Connector 10 includes a dielectric housing 18, such as of molded plastic material, which mounts a plurality of terminals 20. The housing has a forward mating portion 22 which projects through an aperture 24 in panel 12. The mating portion includes a plurality of passages 26 for receiving terminal pins of a complementary mating connector, generally designated 28. In essence, nuts 14 sandwich panel 12 between the nuts and a front portion of connector 10, as will be seen hereinafter. 
     Complementary mating connector 28 includes a forward mating portion 30 for mating with portion 22 of connector 10. Connector 28 includes a dielectric housing 32, mounting a plurality of terminals (not shown). Whereas terminals 20 of connector 10 are adapted for connection to circuit traces on a printed circuit board, the terminals within housing 32 of connector 28 are adapted for termination to a plurality of discrete electrical wires 34 of an electrical cable 36. Mating connector 28 has a pair of jack screws 38 freely rotatably mounted in sleeves 39, with threaded distal ends 38a for threading into internally threaded holes 16 of jack screw nuts 14. The opposite ends of jack screws 38 have slots 40 for receiving an appropriate tool, such as a standard flat-blade screw driver, for threading the screws into nuts 14; if necessary. 
     In the fully assembled, mating condition of connectors 10 and 28, jack screw nuts 14 are effective for securing connector 10 to one side of panel 12, with mating portion 22 projecting through aperture 24 in the panel. Mating portion 30 of complementary connector 28 is mated with portion 22 of connector 10, and the connectors are retained in this mated condition by threading jack screws 38 into nuts 14. 
     Referring to FIG. 2, dielectric (plastic) housing 18 of electrical connector 10 includes a flange portion 42 defining a front face 44. A sheet metal shield, generally designated 46, includes a flange portion 48 juxtaposed against front face 44 of the dielectric housing. The shield includes a forwardly projecting shroud portion 50 surrounding mating portion 22 of the housing. The shield also has a plurality of mounting tabs 52 for mounting the shield to the housing. When connector 10 is secured to panel 12 by jack screws nuts 14 as shown in FIG. 1, the front face of flange portion 48 of shield 46 abuts the back side of panel 12, as shroud portion 50 of the shield projects through aperture 24 in the panel. 
     Referring to FIG. 3 in conjunction with FIGS. 1 and 2, each jack screw nut 14 has an externally threaded shank 54. The threaded shank portion is freely insertable through an enlarged hole 56 in panel 12 and is threadingly engageable in an internally threaded hole 58 in flange portion 48 of sheet metal shield 46. Actually, internally threaded hole 58 in the shield is formed in an inwardly projecting boss portion 60 of the sheet metal shield. Dielectric housing 18 is molded with a recess 62 for accommodating boss portion 60. 
     The retention system of the invention contemplates the provision of a hole 64 in the flange portion 42 of dielectric housing 18 immediately behind internally threaded hole 58 in shield 46, for threadingly receiving shank portion 54 of the jack screw nut after the shank portion passes through threaded hole 58 in the shield. It can be seen that hole 64 in the plastic housing is tapered from a wider mouth 64a nearer shield 46 toward a narrower section 64b further from the shield and towards the rear of the connector. 
     Referring to FIG. 4 in conjunction with FIG. 3, hole 64 in flange portion 42 of plastic housing 18 is generally square in cross-section. As such, externally threaded shank portion 54 of jack screw nut 14 is not required to be self-tapping, and the orthogonal cross-section of hole 64 provides air gaps at the corners of the orthogonal configuration which facilitate the self-tapping action by providing areas for the threads to begin and also provides a reservoir for the accumulation of material from the tapping action. Still further, hole 64 in the plastic housing preferably is not threaded because the size of the hole is selected to ensure that the torque required for the jack screw to tap into this hole is low enough that the combined torque of threaded through hole 58 in the shield and hole 64 in the housing is not excessive. 
     FIG. 5 shows threaded shank 54 of one of the jack screw nuts 14 threaded through hole 58 in boss 60 of sheet metal shield 46. It can be seen that the threaded shank passes freely through hole 56 in panel 12 without any interference. 
     FIG. 6 shows threaded shank 54 of the jack screw nut threaded completely through hole 58 in shield 46 and into unthreaded hole 64 in dielectric housing 18. This represents the condition of connector 10 when completely secured to panel 12 as shown in FIG. 1. During the action of rotating the threaded shank 54 from the position shown if FIG. 5 to that shown in FIG. 6, the threads of shank 54 dig in and actually tap hole 64 to some extent. The strength of the internally threaded hole 58 in the sheet metal shield 46 together with engagement of hole 64 in the plastic housing combine to effectively resist stripping of the threads in hole 58 in the shield. 
     It should be understood that the invention is not limited to the use of jack screw nuts, such as nuts 14 in the exemplary embodiment of the connector assembly shown herein. In some applications, jack screws 38 or other threaded members may be secured directly into the internally threaded holes in the shield of connector 10 to secure a pair of mating connectors together directly, and to retain the connectors in their mated condition. 
     In addition to the embodiment shown in FIGS. 1-6, FIGS. 7 and 8 show some alternate embodiments. Like reference numbers have been used to indicate like elements. In FIG. 7, the tapered square hole 64 is replaced by a tapered circular hole 64&#39;. Circular hole 64&#39; has a wider circular mouth 64a&#39; nearer shield 46 and tapers to a narrower circular mouth 64b&#39; further from the shield and towards the rear of the connector. Furthermore, FIG. 8 shows a combination of the structures of FIGS. 1-6 and 7 by utilizing a hole 64&#34; defined by a pair of opposed flat walls 64c and a pair of opposed arcuate walls 64d. Hybrid hole 64&#34; has a wider hybrid mouth 64a&#34; nearer the shield and tapers to a narrower hybrid mouth 64b&#34; further from the shield and towards the rear of the connector. In the alternative, other shapes could be utilized such as a hexagon, octagon, etc. Finally, although the holes 64, 64&#39; and 64&#34; are shown as being tapered so that the hole is smaller away from the shield 46, such taper is not believed to be necessary to practice the invention. Although not necessary with the square hole 64 shown in FIGS. 1-6, it may be desirable for shank portion 54 of jack screw nut 14 to be self-tapping for some embodiments of the invention including those shown or described herein. 
     It will be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.