Abstract:
A quick disconnect electrical connector resistant to vibration-induced disconnect includes a male connector and a female connector each having opposing segments of flexible thread which inter-engage when the male and female are assembled. The thread segments of the female connector are on a flexible wall which deflects to permit mating engagement when the two connectors are pushed together. The male and female connectors are keyed together when assembled to prevent rotation; and the flexible thread segments engage to prevent unintentional disconnect.

Description:
FIELD OF THE INVENTION 
     The present invention relates to electrical connectors; and more particularly, it relates to electrical connectors of the type which are referred to generally as “quick disconnect” connectors and which are used in commercial and industrial applications, particularly in the field of industrial automation and manufacturing. 
     BACKGROUND OF THE INVENTION 
     Typically, quick disconnect connectors for commercial and industrial applications of the type with which the present invention is concerned, include a male connector and a mating female connector. The male connector has metal connecting elements in the form of pins; and they are received in corresponding sockets or receptacles embedded in the mating female connector. Typically, these connectors have two to five poles plus a ground connection. 
     An important aspect of quick disconnect connectors is that there be some mechanical coupling to secure the male and female connectors together and maintain electrical continuity. Typically, in connectors of this type, the female connector (or the male) is provided with a mating threaded coupling member (such as a coupling nut); and the mating connector is provided with a mating threaded coupling portion so that after the electrical connection is established, the coupling members provide a mechanical connection securing the electrical connection. In some applications where the handling of the connectors may be often and perhaps somewhat rough, as well as in applications where the connectors are mounted to a machine and undergo periodic or continuous vibration, there is a tendency for the coupling nut to back off from its threaded engagement with the male connector, thus creating the possibility of an inadvertent or unintentional disconnect. 
     In addition to the problems mentioned above concerning the possibility that the male and female connectors may become disconnected as a result of vibration or handling, there is also a disadvantage with existing quick disconnect connectors in that it takes an appreciable time to secure a connection, primarily in manually threading the coupling nut of one connector onto the other connector. The amount of time for assembling a single connector combination may not be significant in an absolute sense, but when it is considered that in a large manufacturing environment there are literally thousands of such connectors around and that machines and control systems employing the connectors are continuously being re-positioned, tested and reassembled, over the period of months or a year, the amount of time required to assemble and disassemble threaded coupling nuts has proved to be appreciable. 
     SUMMARY OF THE INVENTION 
     The present invention contemplates that one of the electrical connectors (the female in the embodiment shown) have a cylindrical wall surrounding and spaced from an insulating insert in which connecting elements in the form of sockets are embedded. The cylindrical wall of the female connector is made of molded plastic, such as polyvinyl chloride and has a flexibility such that it may be deformed upon insertion of a mating male connector in order to receive the mating thread segments of the male connector without a turning motion. The interior surface of the cylindrical wall of the female connector is provided with first and second diametrically located, discrete segments of internal threads arranged in opposing relation. That is, one segment of internal threads may extend for approximately 90 degrees about the interior of the cylindrical wall; and a second segment of internal threads is arranged in opposing or facing relation and located on the interior surface of the opposite side of the peripheral wall. Between the two segments of thread, the wall is free of thread and may be smooth and cylindrical. 
     When used in connection with the present invention, the term “thread” includes not only conventional screw threads, extending helically about a central axis, but also a series of alternating ridges or crests and troughs arranged perpendicular to the longitudinal axis of the connector (sometimes referred to as “parallel” threads). Conventional screw threads may be preferred because they are compatible with the screw threads found on the many existing metal or rigid coupling nuts and male connectors found in manufacturing plants. However, parallel threads, when provided in discrete segments as disclosed, will engage and can be assembled by pushing two mating connectors together because the threads are flexible and they are provided in discrete segments so they will ride over one another upon assembly. Parallel threads will provide sufficient interlocking to require separating or pull forces in the range of interest to resist unintentional disconnects. Moreover, a “thread” includes at least two adjacent crest/trough combinations, whether parallel or helical. 
     The male connector preferably has corresponding, matching opposing segments of external thread on an outer cylindrical surface. The male and female connector inserts are keyed together so that when the keyway of the female is aligned with the key of the male connector, the matching thread segments are also aligned. 
     The male connector may then be inserted into the female connector by pushing the male connector directly into the female connector after the respective key and keyway have been aligned. In assembling the male connector to the female connector, the wall of the female connector deflects as the external thread segments of the male connector are assembled to the mating thread segments female connector. In other words, the outer wall of the female connector deforms into an elliptical form so that the interior threads of the female connector ride over the corresponding thread segments of the male connector. 
     Once the two connectors are assembled, the threads inter-engage (whether parallel or helical types). The connector is highly resistant to vibration because the male connector cannot be rotated relative to the female connector since they are keyed together. Moreover, it has been found that a substantial but adjustable pull force (in the range of ten to thirty pounds, for example) may be designed into the assembled connectors, depending upon the hardness of the material used in molding the cylindrical wall of the female connector on which the thread segments are formed and other factors. 
     It will be appreciated that the assembly time for establishing an electrical/mechanical connection with the improved connectors is substantially reduced. Moreover, the female connector of the present invention (with screw threads) is adaptable to mate with existing male connectors having external metal threads, and the male version of the instant connector with screw threads is equally adaptable to assembly with existing inner metal threads of rigid coupling nuts. The male connector of the present invention may be pushed directly into the existing coupling nuts of female connectors, or, if desired, the coupling nuts can be threaded onto the thread segments of the male connectors constructed according to the present invention. 
     Other features and advantages of the present invention will be apparently to persons skilled in the art from the following detailed description of a preferred embodiment accompanied by the attached drawing wherein identical reference numerals will refer to like parts in the various views. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a side view of a male connector and female connector constructed according to the present invention in assembled relation; 
     FIG. 2 is a bottom view of the male connector of FIG. 1; 
     FIG. 3 is a bottom view of the female connector FIG. 1; 
     FIG. 4 is a cross sectional view of the assembled male and female connectors of FIG. 1 taken through the section line  4 — 4  as seen in FIG. 1; 
     FIG. 5 is an end view of the male and female connectors seen in FIG. 1 taken from the right side thereof; 
     FIG. 6 is a cross sectional view of the male and female connectors of FIG. 1 taken along the section line  6 — 6  of FIG. 5 with the threads partially engaged; 
     FIG. 7 is a close-up view similar to FIG. 6 without the cables and with the threads fully engaged; 
     FIG. 8 is an end view of the female connector of FIG. 1 looking at the connecting end thereof; 
     FIG. 9 is a side view of the female connector of FIG. 1 with a partial section of the connecting end thereof, taken along the section line  9 — 9  of FIG. 8; 
     FIG. 10 is a view similar to FIG. 8 of the female connector showing deflection of the flexible wall connection; 
     FIG. 11 is a cross section view of the female connector taken along the section line  11 — 11  of FIG. 10; 
     FIG. 12 is a side view of the female connector of FIG. 1; 
     FIG. 13 is a cross section view taken along the section line  13 — 13  of FIG. 12; 
     FIG. 14 is an enlarged side view of the male connector of FIG. 2; 
     FIG. 15 is a cross section view taken along the section line  15 — 15  of FIG. 14; 
     FIG. 16 is an enlarged end view of the connecting end of the male connector of FIG. 2; and 
     FIG. 17 is a cross section view taken along the section line  17 — 17  of FIG.  16 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1-3, reference numeral  10  generally designates a male electrical connector, and reference numeral  11  generally designates a female electrical connector. The connectors  10 ,  11  are shown in assembled relation in FIG. 1, the male connector is shown in bottom view in FIG. 2, and the female connector is similarly shown in FIG.  3 . As used herein, the terms “forward” or “distal” with reference to a connector, whether male or female, refers to the connecting end—that is, the end which couples to the mating connector. The terms “proximal” or “rear” refer to the portion of a connector closer to its associated cable. 
     Turning first to the female connector  11 , it is shown in greater detail in FIGS. 8 through 13. However, as seen in FIGS. 1 and 3, the exterior of the female connector includes an overmold body designated  12  which encompasses the connecting elements, to be described. The connecting elements may be conventional, and they are conventionally connected to the individual wires of a jacketed cable  13 . The overmold body  12 , as is known, provides a protective coating over the juncture between the cable  13  and the individual connector elements of the connector  11 , as will be described. Moreover, the overmold  12  provides a protective sheath and strain relief for the connector. Similarly, the male connector includes an overmold body  14  and it may be connected to the individual wires of a cable  15 . The overmold bodies  12 ,  14  are made of molded plastic such as polyvinyl chloride. 
     Turning then to the female connector  11  as seen in FIGS. 8-13, it includes an insert body  18  of rigid plastic material and having insulating properties to receive and support individual female connecting elements  19  which are conventional sleeves or receptacles, and a separate, central sleeve  20  for a ground connection. Referring particularly to FIG. 11, the female insert  18  includes a base  22  on which the overmold  12  is formed. To provide greater mechanical bonding with the overmold  12 , the base  22  of the insert may be provided with peripheral grooves such as those designated  24  in FIG.  11 . Extending forwardly (to the right in FIG. 11) the insert  18  includes a generally cylindrical projecting portion  25  integral with the base  22 , and forming a rigid body for holding and supporting the electrical connecting elements  19 ,  20 . 
     As best seen in FIGS. 8 and 11, a keyway or slot  27  is formed in the cylindrical projecting portion  25  which has a diameter less than that of the base  22  in the embodiment shown. Moreover, at the forward portion of the overmold  12 , there is formed a cylindrical wall  28  which surrounds the projecting portion  25  of the insert  18 . An interior cylindrical surface  29  of the cylindrical wall  28  of the overmold is spaced from the cylindrical side of the projecting portion  25  of the insert  18  to form an annular space generally designated  30  which, as will be described, receives a surrounding wall of the male connector. 
     Turning now particularly to FIGS. 8-10, the interior cylindrical surface  29  has integrally molded onto it, first and second segments of inner threads. These two segments are designated respectively  33  and  34 . The threads may be formed in the pattern of a continuous helical thread (screw thread). That is, the crests and troughs of the threads on a segment  33  form the same pitch as, and lead into the threads on the segment  34 . The threads are interrupted however. Moreover, the threads may be a standard thread of screw type found in conventional connectors of this type having coupling nuts with interior threads, in which case, of course, the threads are rigid and continuous, such as a conventional 12 m×1 thread. 
     Alternately, the threads may be parallel—that is, arranged in planes perpendicular to the axis of the connector, designated  35  in FIG.  4 . The thread segments  33 ,  34  are molded as an integral part of the overmold  12 , and therefore made of the same material and flexible. The molding material may be a polyvinyl chloride, and have a durometer rating in the range of approximately 70-100 on the Shore A scale. For the standard thread size indicated above, a durometer rating of 80 on the Shore A scale provides a 15 pound pull force required to disconnect the female connector from the male connector to be described. A durometer rating of 92 on the Shore A scale for the structure described results in a pull force of approximately 25 pounds to disconnect the male and female connectors. 
     Persons skilled in the art will appreciate that pull forces may be designed over a wide range by adjusting the number of threads, the included angle over which the thread segments extend and the hardness of the molding material of the overmold body. 
     Turning particularly to FIG. 9, the thread segment  33  formed on the interior surface  29  of the peripheral wall  28  is seen to be similar to a corresponding thread formed in a rigid coupling nut of the type presently commercially available, however, the segment is not continuous around the interior of the peripheral wall  28 , and the threads are made of a flexible plastic material. The leading edge of the wall  28  may be chamfered as seen at  37  in FIG. 9 to provide a guide or centering surface when connecting male and female connectors, and to engage with a correspondingly chamfered surface  50  on the male connector. The interface may thus provide a seal against dust, debris and water, though the seal is not intended to be a pressure seal. FIG. 13 is a longitudinal cross section of the female connector similar to that seen in FIG. 11, but wherein the connector is rotated 90 degrees on its axis (compare the section lines of FIG.  10  and FIG.  12 ). 
     As seen best in FIG. 1, the overmold material  14  is formed to include an indicator  36  which, in the illustrated embodiment, is in the form of an arrowhead. The indicator  36  may be used in the lining of the male and female connectors during assembly, as will be apparent from further description. A corresponding indicator in the form of an arrow is located on the male connector  10  and designated  38 . 
     Turning now to FIGS. 14-17 a male insert  40 , preferably formed of a rigid, insulating, suitable plastic is generally cylindrical in form and elongated axially as seen in FIG.  15 . Male insert  40  includes, at its forward portion, a cavity which is generally cylindrical and designated  42  for housing a plurality of male contact elements in the form of pins  43 , and a central ground pin  44 . The protective overmold  14  is formed about the exterior cylindrical surface  45  of the male insert  40 , and the male insert  40  also may include grooves  47  to improve the mechanical bond with the overmold  14 . The forward end of the male insert  40  is formed into an outwardly extending peripheral flange  41 . At the forward end of the overmold  14 , there are provided first and second segments of male threads designated respectively  46  and  47  in FIG.  15 . 
     The thread segment  46  is seen in FIG. 14, and it is formed on the outer cylindrical surface  49  of the forwardmost portion of the overmold  14 . Forward of the indicator  38 , and inboard of the cylindrical surface  49 , there is a chamfered or frusto-conical surface  50  for engaging and sealing with the corresponding mating surface  37  of the female connector as described. 
     The male thread segments  46 ,  47  may also be formed as segments of a continuous male screw thread having the same pitch, thread size and diameter as the corresponding inner threads on the female connector, and as the corresponding threads on the rigid metal connectors of conventional female connectors, or they may be parallel ridges/grooves. The included angle of the thread segments of the male connector may also be 90 degrees, as with the corresponding female thread segments. However, the thread segments may extend in the range of 60°-120° approximately with changes in the pull force required for disconnection. 
     The male insert  40  also includes a key  51  which extends axially of the connector and is sized to be received in the keyway  27  of the female insert (see FIGS.  8  and  16 ). 
     Refer now to FIG. 4, when the male connector  10  is assembled to the female connector  11 , as seen in FIG. 4, the key  51  of the male insert  40  is received in the corresponding keyway  27  of the female insert  18 . This not only orients and locates the corresponding connecting elements correctly, but it prevents turning of the connectors once they are connected together. The male connecting elements or pins are received in the corresponding female connecting elements or sockets; and the frusto-conical surfaces  37 ,  50  are in contacting relation. 
     FIG. 6 shows male and female connectors in partial engaging relation. Because both the male thread segments and the mating female thread segments are provided in segments rather than continuous thread, and because the cylindrical wall  28  on which the female thread segments are formed is flexible, when the two connectors are aligned and pushed together, the flexible cylindrical wall  28  of the female connector becomes somewhat elliptical. That is, it bulges out laterally as seen by the dashed line in FIG. 10, because the corresponding male threads push on the female thread segments, and forcing them outwardly; and the opposing unthreaded portions of the wall  28  come closer together, as also illustrated by dashed line in FIG.  8 . The process of assembling a male connector to a female connector gives the user a tactile, feeling indicating correct assembly as the crests of one thread segment ride over the crests and into the troughs of the mating thread segment on the mating female connector. 
     Once the thread segments are assembled, it is assured that corresponding mating thread segments are fully engaged because of the locating function performed by the key and keyway and the chamfered engaging surfaces mentioned above. The removal force, that is, the force necessary to disconnect the male and female connectors, if both connectors are made as indicated herein, depends upon the factors described above. However, in any case, the connector of the present invention is much more resistant to unintentional disconnection through vibration or handling than are the previous connectors made of rigid, full threads and employing a coupling nut. 
     Moreover, the pull force need to disconnect the instant connectors may be varied according to the application or the intention of the manufacturer. Further, the male connector  10  (with flexible screw thread segments) may be used in combination with existing female connectors having rigid coupling nuts, and the female connector  11  may equally well be used with existing commercial connectors having rigid outer threads such as those almost universally used on sensor bodies widely found in current industrial automation applications. 
     Having thus disclosed in detail various embodiments of the invention, persons skilled in the art will be able to modify certain of the structure which has been disclosed and to substitute equivalent materials or elements for those described while continuing to practice the principle of the invention; and it is, therefore, all such modifications and substitutions be covered as they are embraced within the spirit and scope of the independent claims.