Abstract:
A jackscrew system preventing undesired problems during mating and de-mating of miniature electrical connectors. The jackscrew includes a thrust shoulder that separates the jackscrew threads from the remainder of the shaft. A “C-shaped” retaining ring is closed onto a diameter of the jackscrew shaft adjacent shoulder and the head of the jackscrew. A counter-bore is provided in the plug connector body into which the crimp ring enters when under the load of de-mating the connector from the receptacle. The counter-bore acts to restrict the crimp ring from opening under mating and de-mate forces when the thrust shoulder applies such forces against the crimp ring land thereby against the plug body, and thus assures retention of the crimp ring under mating and de-mating operating conditions.

Description:
CLAIM FOR BENEFIT OF EARLIER FILING DATE 
     This application claims the benefit of U.S. Provisional Application No. 60/292,259, filed May 21, 2001, this application having the same tile and inventor as said provisional application. 
    
    
     BACKGROUND OF THE INVENTION 
     The background of the invention will be discussed in two parts. 
     1. Field of the Invention 
     This invention relates to mating and de-mating of electrical connector sub-assemblies having multiple electrical connections that employ a jackscrew to bring the sub-assemblies together in mutual alignment, and more particularly to a two-part jackscrew system for preventing undesired mating and de-mating problems during mating and de-mating of miniature electrical sub-assemblies. Employed is a captive retainer, or thrust ring crimped around the jackscrew shaft that acts to restrict the thrust ring from opening under mounting and de-mounting load forces. 
     2. Description of the Related Art 
     Electrical connector assemblies in which multiple electrical connections are to mate simultaneously commonly consist of two sub-assembly connectors, one generally having an array of male contacts, and another having a corresponding, or complimentary, array of matching receptive female contacts. A pair of jackscrew couplings is commonly used for aligning and capturing the sub-assemblies to effect proper alignment and reliable electrical contact between the two sub-assemblies. 
     Although there have been improvements in related art jackscrew systems, most typically include E-rings for capturing the screw. However, E-rings are prone to dislodge under thrust or screw rotation conditions during mating and de-mating of the assemblies, such dislodgment of the E-ring often accompanied by displacement, or fall-out, of the screw thereby creating serious problems. For instance, E-ring dislodgment often causes electrical shorts in surrounding electrical circuits. Further, the E-ring is substantially larger than the jackscrew shaft in order to provide three-point leveraged locking force with the shaft. During mating and de-mating procedures the E-ring must rotate freely with the shaft and if either ear of the E-ring should encounter an obstacle during such rotation the E-ring, will unlock from the shaft and fall off, thus freeing the jackscrew from the connector body. 
     This has been a problem, especially with miniature connectors, as it is difficult for the E-ring to rotate with the shaft without hitting some part of the plug and thus being forced off the shaft. To enlarge the connector bodies to accept the E-ring would be contra-productive for miniaturization of the connectors. A known apparatus for mating an electrical plug and receptacle having a jackscrew E-ring in accordance with the prior art is disclosed in U.S. Pat. No. 4,865,560 issued to Thomas on Sep. 12, 1989, which patent is incorporated by reference herein. 
     Other jackscrews and jackscrew couplings, exemplary of the related art for mating and de-mating electrical assemblies having multiple electrical connectors, are shown and described variously in U.S. Pat. No. 5,391,091 issued to Nations on Feb. 21, 1995, U.S. Pat. No. 5,628,653 issued to Haas et al. on May 13, 1997, U.S. Pat. No. 5,766,035 issued to Alibert on Jun. 16, 1998, and U.S. Pat. No. 6,056,581 issued to Rothenberger on May 2, 2000. 
     However, in light of prior art problems, what is needed is improved jackscrew means for mounting and de-mounting electrical sub-assemblies that provides mechanical and electrical reliability, uses a minimum number of parts, is inexpensive to produce, and can be quickly assembled and replaced with assured quality and reliability. It is thus an object of the present invention to provide an improved two-part jackscrew system that instead of an E-ring, employs.a captive retainer, or thrust ring, crimped around the jackscrew shaft that acts to restrict the thrust ring from opening under mounting and de-mounting load forces. The present invention has particular application to miniature electrical assemblies having multiple electrical connectors. 
     SUMMARY OF THE INVENTION 
     The present invention is directed toward providing an improved jackscrew system preventing undesired problems encountered in mating and de-mating of electrical sub-assemblies having multiple electrical connectors, and especially of miniature electrical sub-assemblies. 
     This improvement is accomplished by providing a two-part jackscrew system that captivates the screw during mating and de-mating of the electrical connectors thus preventing problems arising from dislodgment of the screw. The system utilizes a thrust shoulder addition to the jackscrew that separates the jackscrew threads from a non-threaded portion of the screw shaft, and a retaining or crimp, ring. The retaining ring is generally C-shaped in the form of an annular ring, or washer, with an annular portion removed. The ring is crimped, or closed, about the non-threaded portion of the jackscrew shaft and positioned substantially against the thrust shoulder. The ring is fabricated of spring material and has a thickness approximately one-third of the inner diameter of the ring. The ring edges are substantially free of burrs and have corner radii of about 0.001 inches. 
     A counter-bore is provided in the connector, or plug, body that accepts the jackscrew. The crimp ring enters the counter-bore when under the load of de-mating this connector, or plug, body from the mated, or receptacle, connector body. The counter-bore acts to restrict the crimp ring from opening under de-mate forces when the thrust shoulder applies such forces against the crimp ring and thereby against the plug body, and thus assures retention of the crimp ring under operating conditions. 
     Thus, in operation as described, for each of the jackscrews the interrelated action of the jackscrew, jackscrew shoulder, retaining ring, and the body surface of the counter-bored recess collectively serve to capture the jackscrew to prevent the usual de-mounting problems associated with mating and de-mating electrical sub-assemblies. 
     The plug body counter-bore further serves to provide an axial tolerance to assure sufficient jackscrew thread engagement with the receptacle body. Additionally, the crimp ring, when crimped around the jackscrew shaft, creates thrust interaction with the screw shoulder to allow for self-centering of the screw when engaged with the receiving threads of the receptacle body. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the jackscrew system of the invention showing the connector housing and an exploded view of the jackscrew and retainer ring; 
     FIG. 2A is a perspective view of the jackscrew system as shown in FIG. 1 connected to the connector housing, 
     FIG. 2B shows in perspective view a second connector housing to be mated to the connector housing of FIG. 1, and 
     FIG. 3 is a cross-sectional view of the jackscrew system showing mating of the housings of FIGS. 2A and 2B with the jackscrew and retainer ring as viewed along line  3 — 3  of FIG.  2 A. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention relates to a jackscrew system for mating and de-mating miniature electrical sub-assemblies having multiple electrical connectors, and more particularly, to a jackscrew system preventing undesired mounting and de-mounting problems during connection and disconnection of the sub-assemblies. Although in mating and de-mating of miniature electrical sub-assemblies two jackscrew systems are normally used, for simplicity only one will be described. Referring now to the drawings wherein the same reference numerals designate the same elements in the various views, the details of the invention will be described. 
     As shown in FIG. 1, the jackscrew system of the invention is comprised of two parts, the jackscrew generally designated  10 , and the retaining, or crimp, ring  20 . Jackscrew  10  includes jackscrew head  11  with a shaft extending longitudinally therefrom, the shaft having a non-threaded portion  12  immediately following head  11  terminated by a shoulder  13  extending axially from portion  12 , and then following the shoulder  13  a threaded portion  14  that completes the shaft. 
     The non-threaded portion  12  may include a shear-groove, such as groove  41 , directly following, or beneath, the head  11 . This shear-groove acts to cause head  11  to shear off from the shaft when excess torque is applied to head  11 . The exposed shaft may then be easily accessed, removed and replaced. Otherwise, shearing may occur at the minor thread diameter within the receiving threaded area resulting in inability to remove the captured broken off threaded portion. 
     As further shown, sub-assembly connector  30  has connected thereto multiple electrical leads  33  and apertures  31  (see FIG. 3) for receiving the jackscrew system in accordance with the invention. Apertures  31  have counter-bored recesses  32  for receiving retaining ring  20  as will hereinafter be further described. 
     Retaining, or crimp, ring  20 , shown apart from connector body  30 , is generally C-shaped in the form of an annular ring, or washer, with an annular portion removed. Although the portion removed is not of a dimension to allow for normal fitting of the ring over the non-threaded portion  12  of jackscrew  10 , the flexibility of the material of the ring  20  permits it to be crimped, or snapped, in the usual manner onto non-threaded portion  12 . The removed portion is such that upon being crimped onto non-threaded portion  12  substantially against the thrust shoulder  13 , the open ends, or tangs, may abut each other but not overlap. 
     Typically for miniature connectors in accordance with the invention, the ring  20  is made of stainless spring steel material with a pre-crimp outside diameter of approximately 0.070 inches and an inside diameter of approximately 0.037 inches. In order to withstand the stress to be experienced during mating and de-mating of the connectors, the thickness of the ring  20  is approximately one third (⅓ rd ) of the inside diameter. However, this thickness can vary depending on the other dimensions and/or composition of the selected ring material. To prevent scouring and material break-off, it is important that “burrs” or other irregularities on the outside diameter surfaces of the ring  20  are minimized. It is further desirable that the corners of these surfaces are rounded to radii of about 0.001 inches. 
     Referring to FIG. 2A, there is shown jackscrew  10  positioned in sub-assembly connector body  30  in accordance with the invention. Jackscrew  10  is inserted through aperture  31  of connector body  30  with crimp ring  20  crimped, or snapped, loosely onto non-threaded portion  12  behind shoulder  13 . FIG. 2B shows sub-assembly connector body  40  to be mated to connector body  30 . As shown, body  40  has electrical leads  43  corresponding as required to leads  33 , and threaded apertures  41  for receiving threaded portion  14  of jackscrew  10 . 
     FIG. 3 best shows the jackscrew system in accordance with the invention, showing in cross-section the mating of the housings of FIGS. 2A and 2B with the jackscrew  10 ; and retainer ring  20  as viewed along line  3 — 3  of FIG. 2A; Referring primarily to FIG. 3, the diameter of jackscrew shoulder is designed to be less than that of aperture  31  and the length of jackscrew  10  is such that shoulder  13  can be projected through aperture  31  and into counter-bored recess  32  The diameter of jackscrew head  11  is greater than that of aperture  31  to restrict head  10  from entering aperture  31 . 
     C-shaped retaining ring  20  has an outer diameter smaller than the diameter of counter-bore  32  but larger than the diameter of recess  31  and thus of shoulder  13 . In operation, jackscrew  10  is inserted through recess  31  a distance to permit shoulder  13  to exit counter-bored recess  32  sufficiently so that retaining ring  20  can be crimped onto jackscrew shaft portion  12  behind shoulder  13 . Thus, as shown in FIG. 3, dimension α must be sufficiently less than dimension φ to allow shoulder  13  to project far enough from counter-bore  32  so that ring  20  may be properly crimped onto jackscrew shaft  12 . Additionally, the configuration of jackscrew  10  is such that shoulder  13  does not meet the threads of receptacle connector  40  when it is fully mated to plug connector  30 . 
     The inner diameter of crimp ring  20  is smaller than the diameter of the shoulder  13  with the outside diameter larger than that of both shoulder  13  and recess  31 . Thus, when crimped in place onto non-threaded portion  12  adjacent shoulder  13 , ring  20  operates to capture and prevent removal of the jackscrew  10  from the plug body  30 . Since the jackscrew head  11  is of a diameter to prevent passage through the recess  31 , the combination of the crimped retainer ring  20  and jackscrew head  11  capture the jackscrew  11  within the connector plug  30 . 
     Thus, it is seen that connector body  30  has recess  31  for accepting the shaft of jackscrew  10  therethrough and counter-bore  32  for accepting retaining ring  20 , with threaded portion  14 , shoulder  13  extending through counter-bore  32  sufficiently to allow retaining ring  20  to be crimped onto non-threaded portion  12  adjacent shoulder  13  between head  11  and shoulder  13 . Jackscrew head  11  and counter-bore  32  have diameters greater than that of recess  31  with counter-bore  32  terminating in an interior surface downsizing at surface  33  to recess  31 . Thus, as explained, shoulder  13 , retaining ring  20  and interior surface  33  cooperate to capture jackscrew  10  within sub-assembly housing  30  during mating and de-mating procedures. 
     When mating the connector plug  30  to connector receptacle  40 , the jackscrews are inserted to protrude through recesses  31  and counter-bores  32  and retainer ring  20  is crimped onto nonthreaded portion  12  as explained. Connector bodies  30  and  40  are then initially engaged and jackscrew  10  is rotated clockwise within body  30  to progressively engage threads  41  of body  40 . 
     With continued rotation the force of the jackscrew head  11  against the body  30  draws body  30  and receptacle  40  together to complete the aligned mating of the bodies. The location of the shoulder  13  on jackscrew  10  is such that with ring  20  crimped to shaft  12 , shoulder  13  does not meet the threads  41  of the receptacle  40  when the bodies  30  and  40  are fully mated. The counter-bore  32  further serves to provide an axial tolerance to assure sufficient jackscrew thread engagement with the receptacle body  40 . Additionally, crimp ring  20 , when crimped around the shaft of jackscrew  10 , creates thrust interaction with screw shoulder  3  to provide for self- centering of the screw  10  when engaged with receiving threads  41  of receptacle body  40 . 
     When de-mating the connectors, jackscrew  11  is rotated counter-clockwise to progressively disengage the jackscrew threads  14  from the coupling threads  41  of body  40 . Since the outer diameter of ring  20  is greater that the diameter of recess  31 , this progressive disengagement causes the jackscrew shoulder  13  to force retaining ring  20  against the surface  33  of counter-bored hole  31 , jackscrew  10  therefore being restrained from opening under the applied de-mating forces. Retainer ring  20  thus acts as a thrust bearing between the shoulder  13  and the plug body  30  to disengage bodies  30  and  40 . 
     In operation as described, the interrelated action of the ring  20  and the body surface  33  of counter-bored recess  32  thus captures the jackscrew, provides transaxial mating tolerance within counter-bore  31 , and enables controlled mating and de-mating of the sub-assemblies. This interrelation prevents undesirable mating and de-mating problems associated with conventional jackscrews. Thus, in accordance with the present invention there has been shown and described a jackscrew system for mating and de-mating multiple connector electrical sub-assemblies, and more particularly, to a jackscrew system preventing undesired mounting and de-mounting problems of miniature electrical sub-assemblies. 
     While there has been shown and described a preferred embodiment, it is to be understood that various other adaptations and modifications will be apparent to those skilled in the art. It is intended that such adaptations and modifications be encompassed in the following claims.