Abstract:
A coaxial connector may be configured with multiple interleaved concentric threads that reduce connector assembly threading requirements. A cable sheath stripping feature may be incorporated into the connector, eliminating the need for a separate sheath stripping tool. Also, a pair of internal rings may be added which co-operate to couple the connector body with a rotatable inner coupling sleeve until a predetermined level of torque is applied whereupon complementary protrusions formed on the rings deform and slip past each other, protecting the connector from damage due to application of excessive torque and eliminating the need for torque wrenches during connector installation.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention generally relates to coaxial cable connectors. More specifically, the present invention relates to a coaxial cable connector with ease of installation features that is installable with reduced connector specific tooling requirements.  
         [0003]     2. Description of the Prior Art  
         [0004]     Coaxial cable connectors are used, for example, in communication systems requiring a high level of reliability and precision. A connector that is poorly installed may damage equipment, significantly degrade system performance and or lead to premature system failure. Therefore, prior connectors typically include extensive installation instructions that require costly specialized tools specific to each connector.  
         [0005]     One specialized tool for connectors is the jacket stripper. The jacket stripper is used to accurately strip away outer sheathing from the coaxial cable to expose a specified length of outer conductor for electrical contact with the desired surfaces of the connector. If the amount of outer sheathing removed is short, long or non-uniform, the electrical connection and or the environmental seal of the connector to the cable may be degraded.  
         [0006]     Connectors may be used in confined spaces, for example among banks of cables with minimal spacing between them. Confined spaces increase the difficulty of proper connector installation and or interconnection by increasing the time required to make repeated small turns allowed by the confined space when threading the connectors by hand and or with the aid of a wrench. Also, connectors may be installed in exposed locations such as the top of radio towers where installation personnel may be less inclined to properly follow time-consuming installation procedures.  
         [0007]     Threaded connections on and between connectors are typically tightened using wrenches having the potential for large moment arm force generation that may damage the connector and or associated cable(s). Therefore, use of a torque wrench with a torque setting specific to each connector is often specified by the prior connector installation instructions. Applying the proper torque, for example 15-20 lb-inches, to threaded connections ensures correct electrical interconnection and prevents application of excessive force that may deform or otherwise damage threads, seals and or the relatively soft metal(s) of the cable(s). The torque wrench is a costly and easily damaged tool that the installation personnel may not always have on hand or bother to use correctly, if at all.  
         [0008]     Competition in the coaxial cable connector market has focused attention on minimization of overall costs, including training requirements for installation personnel, reduction of dedicated installation tooling and the total number of required installation steps and or operations.  
         [0009]     Therefore, it is an object of the invention to provide a connector that overcomes deficiencies in the prior art.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention.  
         [0011]      FIG. 1  is a partial cut-away side view of a coaxial connector according to one embodiment of the invention and a coaxial cable for receiving the connector.  
         [0012]      FIG. 2  is an external side view of a rear clamp nut according to one embodiment of the invention.  
         [0013]      FIG. 3  is a side section view, along line A-A, of  FIG. 2 .  
         [0014]      FIG. 4  is an end section view, along line B-B, of  FIG. 2 .  
         [0015]      FIG. 5  is an external side view of a rear clamp nut according to another embodiment of the present invention.  
         [0016]      FIG. 6  is a partial cut-away side view of a coaxial connector according to another embodiment of the invention.  
         [0017]      FIG. 7  is an end section view, along line A-A, of  FIG. 6 .  
         [0018]      FIG. 8  is an end view of  FIG. 6 .  
         [0019]      FIG. 9  is an end view of a finger ring according to the embodiment of the invention shown in  FIGS. 6-8 .  
         [0020]      FIG. 10  is a side section view, along line A-A, of the finger ring shown in  FIG. 9 .  
         [0021]      FIG. 11  is an end view of a ramp ring according to the embodiment of the invention shown in  FIGS. 6-8 .  
         [0022]      FIG. 12  is a side view of the ramp ring shown in  FIG. 11 . 
     
    
     DETAILED DESCRIPTION  
       [0023]     As shown in  FIG. 1 , a connector  1  for use with a coaxial cable  5  has a rear clamp nut  10  adapted to fit over an end portion of the cable  5 . A sheath  20  of the cable  5  is removed from the end of the cable  5  to expose the outer conductor  15 . Threads  25  operate to clamp the outer conductor  15  between the connector body  50 , a circular coil spring  31 , a thrust collar  33  and an inner collar  26  coupled to the rear clamp nut  10  via an over tightening protection assembly  24 , described herein below, to secure the connector  1  to the cable  5 . If the over tightening protection assembly  24  feature is not used, the threads  25  may be formed on the clamp nut  10  and the inner collar  26  omitted. Also, the circular coil spring  31  may be omitted and the outer conductor  15  clamped directly between the connector body  50  and the inner collar  26  or the rear clamp nut  10 . An inner conductor  27  of the coaxial cable  5  engages an inner contact  30  of the connector  1  that is spaced away from the outer conductor  15  mating surfaces by an insulator  35 .  
         [0024]     A cable stripping feature of the connector  1  is demonstrated by  FIGS. 2-4  which show a simplified version of the rear clamp nut  10 . The rear clamp nut  10  has a rear clamp nut bore  32  with a first inner diameter D 1  at the cable end  28  of the connector  1  adapted to receive the coaxial cable  5  with sheath  20 . A smaller second inner diameter D 2  of the rear clamp nut bore  32  at a connection end  29  is adapted to receive only the outer conductor  15  of the cable  1 .  
         [0025]     A slot  40  formed in the rear clamp nut  10  has a cutting edge  45  at the end of a helical step  47  between the first inner diameter and the second inner diameter. When the rear clamp nut  10  is placed over the end of the cable  5 , the sheath  20  bottoms against the helical step and the cutting edge  45 . Rotating the rear clamp nut  10  about the cable  5  drives the sheath  20  against the cutting edge  45  which cuts and separates the sheath  20  from the outer conductor  15 . The cut portion of the sheath  20  exits through the slot  40  as the rear clamp nut  10  is advanced over the cable  5 . The sheath  20  is trimmed to the correct length, for example, when the outer conductor  15  reaches the connection end of the rear clamp nut  10 .  
         [0026]     The rear clamp nut  10  may be attached to the connector body  50  via threads  25  shown in detail on  FIG. 5 . The threads  25  comprise four interleaved concentric threads equally spaced from each other along the length of the connector. Each of the four threads has the same lead with thread ends spaced 90 degrees apart from each other around the axis of the connector  1 . The interleaved threads  25  have a pitch that is four times normal, resulting in threaded assembly of the connector  1  requiring only one quarter the number of turns compared to a common single thread. Because the threads  25  are interleaved, the threads maintain the same overall thread to thread contact area resulting in a thread  25  with strength comparable to common single threading but with a pitch that is increased by a factor of 4. In alternative embodiments, use of two or three interleaved concentric threads will result in a one half or one third reduction, respectively, in the number of turns required to attach the rear clamp nut  10  to the connector body  50 . Flats  55  formed in the outer surface of the rear clamp nut  10  and connector body  50  provide tool surfaces for the tightening of rear clamp nut  10  against the connector body  50 .  
         [0027]     One or more over-tightening protection assembly(s)  24  of the connector  1  prevents damage to the connector body  50 , rear clamp nut  10  (if present), threads, seals and or the relatively soft metal(s) of the cable(s). A separate over-tightening protection assembly  24  may be applied to operate with respect to the threads  25  and the connector threads  56 , each with a separate desired torque rating. The over-tightening protection assembly  24  is explained with the aid of a simplified version of connector  1 , as shown in  FIGS. 6-8 . The connector body  50  has an aperture dimensioned to accept an inner coupling sleeve  60 . The inner coupling sleeve  60  has connector threads  56  located on an inner diameter  59  for coupling with other connectors and or equipment. The inner coupling sleeve  60  is retained in a rotatable configuration by an inward protruding coupling sleeve flange that overlaps a corresponding outer protruding interface flange  62  of an interface  63  that is press fit into the cable end  64  of the connector  1 .  
         [0028]     Rotation of the connector body  50  is coupled, within a selected torque range, to the inner coupling sleeve  60  by a first ring and a second ring having complementary protrusions. To describe the first and second rings interaction in detail, a specific embodiment wherein the first ring is a finger ring  65 , as shown for example in  FIGS. 9 and 10 , which mates with the second ring which is a ramp ring  70 , as shown for example in  FIGS. 10 and 11 , will hereinafter be described.  
         [0029]     The finger ring  65  and the ramp ring  70  may be located coaxially within a groove  52  formed in the connector body  50 . The finger ring  65  may be keyed to the connector body  50  by a plurality of first ring tab(s)  75  distributed around the inner diameter of the groove  52  which interlock with corresponding finger ring slot(s)  76  in the finger ring  65 . Similarly, the ramp ring  70  may be keyed to the inner coupling sleeve  60  by a plurality of inward projecting second ring tabs  77  that couple with inner coupling sleeve slot(s)  78  formed in, for example, a cable end of the inner coupling sleeve  60 . Finger(s)  80  projecting inward from the finger ring  65  engage the ramp(s)  85  extending outwards from the ramp ring  70 .  
         [0030]     Rotation of the connector body  50  is transmitted to the inner coupling sleeve  60  for threading of the connector threads  56  until a predetermined torque value is reached whereupon the finger(s)  80  of the finger ring  65  and or the ramp(s)  85  of the ramp ring  70  momentarily deforms and slips past the ramp ring  70  or vice versa, preventing application of out of range torque levels to the inner coupling sleeve  60  and thereby to the connector threads  56 , gaskets and or the relatively soft metal(s) of the cable(s). During reverse rotation, the finger(s)  80  impact a step side of the ramp(s)  85  having an increased angle ensuring that increased torque levels sufficient to enable unthreading of the connector  1  may be applied.  
         [0031]     The torque value at which the finger ring  65  slips past the ramp ring  70  may be adjusted by selecting materials with desired bending/deformation characteristics; adjusting the angles of the mating surfaces of the finger(s)  80  and or ramp(s)  85 ; and or modifying the thickness of the selected material(s). For example, the finger ring  65  may be formed by a process comprising metal stamping, bending and ring rolling and the ramp ring  70  may be injection molded of a plastic such as nylon. Similarly, the positions of the finger and ramp ring pairs may be switched and or either or both of the first and second rings replaced with other forms of complementary protrusions and or interlocking structures of which at least one of a complementary pair will deform and release the connector body  50  to inner coupling sleeve  60  interlock when the applied rotation torque reaches a desired threshold level. For example, interlocking protrusions, bumps, arches and or leaf springs may be used with an equivalent effect according to the invention.  
         [0032]     One skilled in the art will appreciate that the cable end of the connector  1  may be adapted to mate with the dimensions and configuration of a specific coaxial cable  5 , for example a coaxial cable with annular or helical corrugations in the inner and or outer conductors  27 ,  15 . Further, the connector end of the connector  1  may be adapted to mate according to male and or female embodiments of a proprietary interface or one of the standard connector types, for example BNC, Type-N or DIN.  
         [0033]     The present invention provides coaxial connectors with ease of installation features and reduces specialized installation tool requirements. The sheath stripping cutting edge slot eliminates the need for a dedicated sheath stripping tool and strips the sheath to the correct outer conductor exposure during connector assembly without requiring a separate stripping step. Interleaved threads allow the connector to be installed with a significantly reduced threading requirement. Also, protection from damaging excess torque application during connector installation and elimination of the need for torque wrenches is built into the connector.  
         [0034]     Table of Parts  
                                       1   connector       5   coaxial cable       10   rear clamp nut       15   outer conductor       20   sheath       24   gasket       25   threads       26   inner collar       27   inner conductor       28   cable end       29   connector end       30   inner contact       31   circular coil spring       32   rear clamp nut bore       33   thrust collar       35   insulator       40   slot       45   cutting edge       47   step       50   connector body       52   groove       55   flats       56   connector threads       59   inner diameter       60   inner coupling sleeve       62   interface flange       63   interface       64   cable end       65   finger ring       70   ramp ring       75   first ring tab       76   finger ring slot       77   second ring tab       78   inner coupling sleeve slot       80   finger       85   ramp                  
 
         [0035]     Where in the foregoing description reference has been made to materials, ratios, integers or components having known equivalents then such equivalents are herein incorporated as if individually set forth. While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus, methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of applicant&#39;s general inventive concept. Further, it is to be appreciated that improvements and/or modifications may be made thereto without departing from the scope or spirit of the present invention as defined by the following claims.