Abstract:
The invention provides a connector for coax cable with a snap bearing providing the interface between the inner body and the outer body. A concave surface below the snap bearing, which is retained by a pair of shoulders, allows the snap bearing to elastically deform during assembly of the connector to thereby reduce the risk of plastic deformation of the components while allowing significant improvements in overlap at the interface of the components.

Description:
FIELD OF THE INVENTION 
   This invention relates to connector bodies for coaxial cables. 
   BACKGROUND OF THE INVENTION 
   For small assemblies, such as coaxial connectors, it is often desirable to use components that are configured to snap together rather than use fasteners. In certain connectors, two parts that are to rotate relative to one another are snapped together with a snap ridge of one part engaging a groove in the other part. The overlap between the components in such connections is typically kept to a minimum, such as a few thousandths of an inch of overlap in brass components, in order to minimize plastic deformation of the components during assembly. The minimal overlap results in high bearing pressures and high friction forces in the interface between the components resulting in wear and degradation of the snap ridge. A terminator connector having a snap fit between an outer body and an inner body is described in U.S. Pat. No. 6,491,546, issued to Jason Perry, the disclosure of which is herein incorporated by reference. 
   Snap bearings may be used to allow the rotation of one part with respect to another while substantially increasing the overlap between the components. A typical snap bearing is split to allow the bearing to be stretched over a ridge during assembly. However, radial loads, such as those applied during assembly, may cause deformation of conventional snap bearings. 
   Therefore, an improved interface between components in a coax connector with increased overlap and reduced risk of plastic deformation of the components is desired. 
   SUMMARY OF THE INVENTION 
   The invention is a coaxial cable connector having a snap bearing interface between an inner body and an outer body, wherein the outer body is rotatable about the inner body. The bearing is a split snap bearing with a ridge for engaging a groove in the outer body. The snap bearing is retained between two shoulders on the outer surface of the inner body with a concave surface between the shoulders and below the bearing&#39;s ridge. The edges of the bearing are supported by a ledge proximate to each of the shoulders. Thus, the snap bearing provides radial and axial support for the outer body. 
   In one form, the invention includes a coaxial cable connector comprising an inner body with an outer surface having a retaining shoulder, a snap shoulder, and a concave surface therebetween; and a split bearing engaging the inner body between the retaining shoulder and the snap shoulder. 
   In another form, the invention includes a coaxial cable connector that comprises an outer body with an inner surface having a retaining shoulder, a snap shoulder, and a concave surface therebetween; and a split bearing engaging the outer body between the retaining shoulder and the snap shoulder. 
   In another form, the invention includes a coaxial cable connector comprising an inner body, an outer body that is coupled to the inner body, an interface between the inner body and the outer body having a retaining shoulder, a snap shoulder, and a concave surface therebetween, and a split bearing engaging the interface between the retaining shoulder and the snap shoulder. 
   In another form, the invention includes a method for assembling a coaxial cable connector. The method comprises the steps of providing an inner body having a concave surface and a snap shoulder; sliding a split bearing over the snap shoulder to substantially cover the concave surface, the split bearing having a ridge projecting away from the concave surface; and inserting the inner body into an outer body such that the outer body contacts the ridge and deflects the split bearing toward the concave surface until the ridge engages a groove defined by the outer body. 
   An advantage of the present invention is that the concave surface allows the center span of the snap bearing to flex during assembly of the components of the connector without exceeding the elastic limit of the bearing. The concave surface thus allows for a large bearing surface, thus reducing the bearing pressures on the components. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is disclosed with reference to the accompanying drawings, wherein: 
       FIG. 1  is a partially cut-away isometric view of the coaxial connector of the present invention; 
       FIG. 2  is an isometric view of the inner body and snap bearing of the present invention; 
       FIG. 3  is an isometric view of the inner body and the unassembled snap bearing of  FIG. 2 ; 
       FIG. 4  is a partially cut-away isometric view of the inner body and snap bearing of  FIG. 2 ; and 
       FIG. 5  is a an isometric view showing the connector and the specialized tool. 
   

   Corresponding reference characters indicate corresponding parts throughout the several views. The examples set out herein illustrate several embodiments of the invention but should not be construed as limiting the scope of the invention in any manner. 
   DETAILED DESCRIPTION 
     FIG. 1  shows the coaxial connector of the present invention. By way of example, the connector described is a tamper-resistant terminator connector, though the invention may also be applied to other coax connectors having an outer part that rotates relative to an inner part. The connector  10  includes an inner body  12 , a snap bearing  14 , and an outer body  16 . 
   The inner body  12 , as shown in  FIGS. 2 and 3 , includes a retaining shoulder  20 , a snap shoulder  22 , and a concave surface  24 . The concave surface  24  includes an edge  26  proximate to each of the retaining shoulder  20  and the snap shoulder  22 . In a particular embodiment, the edges  26  are narrow with respect to the concave surface  24  as illustrated in the figures. The inner body  12  further includes inner threads  28  configured for engaging a coaxial port (not shown) and slots  30  configured for engaging a specialized tool  31  ( FIG. 5 ) for threading the threads  28  onto the coaxial port after the terminator connector  10  has been assembled. The specialized tool  31  is of the type that are generally available to cable installers, but not the general public. The tool  31  includes a pair of spring-loaded feet  50  that may be inserted into the end of the terminator connector  10  to engage the slots  30 . 
   The optional ramps  32  engage fingers (not shown) on the inner surface of the outer body  16  to allow the outer body  16  to rotate about the inner body  12  in one direction only. The inner body  12  may be configured for receiving a resistor case with a resistor that engages the center conductor of the coax port when the terminator connector is affixed to the coax port. The resistor is chosen to have a similar impedance as coaxial cable, such as 75-Ω, to properly terminate the port. The inner body  12  further includes an interior transverse wall for preventing access to the coax port through the terminator connector  10 . The inner body  12  may be made of a metal, such as brass, or other suitable materials, such as Ultem™, a durable platic, and glass-filled polycarbonate. 
   The snap bearing  14  is a split bearing having a ridge  34  on the outer surface thereof. The ridge  34  is ramped in the illustrated embodiment to allow easier assembly of the outer body  16  onto the snap bearing  14  and to provide axial support to the outer body  16  in one direction. In an alternative embodiment, the ridge  34  is not ramped to thereby provide axial support to the outer body  16  in two directions. In a particular embodiment, the snap bearing  14  comprises a substantially high strength plastic, such as acetal, or metal having a lubricious coating or plating to maximize the reduction of friction of the bearing. 
   The outer body  16 , shown in  FIG. 1 , includes a groove  36  corresponding to the ridge  34  and outer threads  38  configured for engaging the outer threads of a coaxial cable. The outer body  16  is made of metal, such as brass, or another substantially rigid material, such as Ultem™ or glass-filled polycarbonate. The outer body  16  generally follows the contours of the inner body  12  while providing clearance between the inner body  12  and the outer body  16 . A connector cap  40  includes an end that snaps onto the inner body  12  proximate to the inner threads  28 . 
   The terminator connector is assembled by stretching the snap bearing  14  such that the leading edge  42  fits over the snap shoulder  22  and then forcing the snap bearing  14  forward so that the bearing slides over the snap shoulder  22  and snaps into place between the retaining shoulder  20  and the snap shoulder  22  as shown in  FIG. 2 . The leading edge  42  may pivot downward toward the concave surface  24  during assembly to minimize the strain on the snap bearing  14 . The invention thus reduces the risk of reaching the elastic limit of the snap bearing  14  during assembly by providing the concave surface  24 . The edges  26  support the snap bearing  14 . The connector cap  40  is assembled by snapping onto a barb  44  external to the threads  28 . 
   The outer body  16  is assembled by inserting the end of the inner body  12  having the slots  30  into the axial bore of the outer body  16  until the leading end of the outer body  16  slides over the ridge  34  and the ridge  34  snaps into the groove  36 . As the leading end of the outer body  16  slides over the ridge  34 , the snap bearing  14  is able to elastically deform downward toward the concave surface  24  thus avoiding potential permanent deformation of the ridge  34  or the snap bearing  14  as a whole. 
   In use, the feet  50  extending from the specialized tool  31  engage the slots  30  via the axial bore of the outer body  16  proximate to the outer threads  38 . The tool is used to tighten the inner threads  28  onto the coax port. The terminator connector  10  is now connected to the coax port in a tamper-proof way since the inner body  12  is completely encompassed by the outer body  16  and the outer body  16  is free to rotate about the inner body  12  via the snap bearing  14 . The only way to turn the inner body  12  and thus loosen it from the coax port is to use the specialized tool  31  to engage the slots  30 . Thus, unauthorized personnel without access to the tool  31  cannot access the coaxial port with a coaxial cable. In certain situations, such as when a cable is being temporarily disconnected, the disconnected cable may be connected to the outer body  16  by threading the cable&#39;s connector onto the outer threads  38 . The disconnected cable is isolated from the coaxial port by the terminator connector. 
   In an alternative embodiment, the snap bearing is inverted and the retaining shoulder, the snap shoulder, and the concave surface are located on the interior of the outer body. The snap bearing&#39;s ridge thus is directed inward and engages a corresponding groove in the outer surface of the inner body. The terminator connector of the alternative embodiment is assembled similarly as described in the previous embodiment, except that the snap bearing is first assembled into the space between the snap shoulder and the retainer shoulder of the outer body. 
   It should be particularly noted that although the snap bearing retainer of the present invention is shown and described as applied to a tamper-resistant terminator connector, the invention may also be used with other connector types requiring a bearing that provides radial support, axial support, or both. 
   While the invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof to adapt to particular situations without departing from the scope of the invention. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope and spirit of the appended claims. 
   PARTS LIST 
   
       
         10  coax connector 
         12  inner body 
         14  snap bearing 
         16  outer body 
         20  retaining shoulder 
         22  snap shoulder 
         24  concave surface 
         26  edge 
         28  inner threads 
         30  slots 
         31  specialized tool 
         32  ramps 
         34  ridge 
         36  groove 
         38  outer threads 
         40  conductor cap 
         42  leading edge 
         44  barb 
         50  spring-loaded feet of the specialized tool