Abstract:
A compression connector for smooth walled, corrugated, and spiral corrugated coaxial cable includes an insulator disposed within the body, wherein the insulator contains a central opening therein which is dimensioned smaller than a collet portion which seizes a center conductor of the coaxial cable. The connector also includes a clamp disposed inside the body as well as a compression sleeve assembly. An intermediate connector element includes a transitional surface which interacts with the clamp. When an axial force is applied to the compression sleeve, the clamp is forced by the transitional surface into the body, causing the clamp to squeeze onto an outer conductor layer of the coaxial cable. At approximately the same time, the collet portion is forced through the central opening of the insulator, causing the collet portion to squeeze onto the center conductor.

Description:
CROSS REFERENCE TO RELATED APPLICATION[S] 
     This application is a continuation of the earlier U.S. patent application Ser. No. 12/469,313 filed on May 20, 2009 and entitled COMPRESSION CONNECTOR FOR COAXIAL CABLE, now pending, which is a continuation-in-part of and claims priority from U.S. patent application Ser. No. 11/743,633 filed on May 2, 2007 and entitled COMPRESSION CONNECTOR FOR COAXIAL CABLE, now pending, the disclosures of which are hereby incorporated entirely herein by reference. 
    
    
     BACKGROUND 
     1. Technical Field 
     This invention relates generally to the field of coaxial cable connectors, and more particularly to a compression connector for smooth walled, corrugated, and spiral corrugated coaxial cable. 
     2. State of the Art 
     Coaxial cable is installed on a widespread basis in order to carry signals for communications networks such as cable television (CATV) and computer networks. The coaxial cable must at some point be connected to network equipment ports. In general, it has proven difficult to make such connections without requiring labor intensive effort by highly skilled technicians. 
     These generalized installation problems are also encountered with respect to spiral corrugated coaxial cable, sometimes known as “Superflex” cable. Examples of spiral corrugated cable include 50 ohm “Superflex” cable and 75 ohm “coral” cable manufactured by Andrew Corporation (www.andrew.com). Spiral corrugated coaxial cable is a special type of coaxial cable that is used in situations where a solid conductor is necessary for shielding purposes, but it is also necessary for the cable to be highly flexible. Unlike standard coaxial cable, spiral corrugated coaxial cable has an irregular outer surface, which makes it difficult to design connectors or connection techniques in a manner that provides a high degree of mechanical stability, electrical shielding, and environmental sealing, but which does not physically damage the irregular outer surface of the cable. Ordinary corrugated, i.e., non-spiral, coaxial cable also has the advantages of superior mechanical strength, with the ability to be bent around corners without breaking or cracking. In corrugated coaxial cables, the corrugated sheath is also the outer conductor. 
     When affixing a cable connector to a coaxial cable, it is necessary to provide good electrical and physical contact between the cable connector and the center and outer conductors of the cable. It is also desirable to connect the center and outer conductors without having to reposition the cable connector within a connecting tool during the connection operation. Compression connectors for coaxial cable are known which require dual stage compression to independently activate both inner conductor and outer conductor mechanisms, thus requiring a complex compression tool to accomplish the compression when installing the compression connector onto the coaxial cable. 
     SUMMARY 
     Often, to minimize the number of contacts in series in a given electrical path, such as the ground path, within a cable connector, it is desirable to have the moveable clamping element which contacts the outer conductor of a coaxial cable make direct contact with the stationary outer housing of the connector. Such a design is shown in  FIGS. 1-12  of this and the parent application. However, due to particular considerations necessitating maximizing the actual area of contact between components which undergoes wiping as the parts move relative to one another, or to adapt body cavities within the cable connector, which must be large for impedance matching, to clamps which must be small to accommodate fitting of coaxial cable while maintaining flexibility or resilience, an intermediate connector element (or transition member) is inserted between the connector housing and the clamp. 
     Briefly stated, a compression connector for smooth walled, corrugated, and spiral corrugated coaxial cable includes an insulator disposed within the body, wherein the insulator contains a central opening therein which is dimensioned smaller than a collet portion which seizes a center conductor of the coaxial cable. The connector also includes a clamp disposed inside the body as well as a compression sleeve assembly. An intermediate connector element includes a transitional surface which interacts with the clamp. When an axial force is applied to the compression sleeve, the clamp is forced by the transitional surface into the body, causing the clamp to squeeze onto an outer conductor layer of the coaxial cable. At approximately the same time, the collet portion is forced through the central opening of the insulator, causing the collet portion to squeeze onto the center conductor. The collet portion can be designed to be simultaneously squeezed onto the center conductor at the same time the clamp compresses the outer conductor layer, or the engagement of the collet portion with the center conductor can be designed to be delayed. 
     According to an embodiment of the invention, a compression connector for a coaxial cable, wherein the coaxial cable includes a center conductor surrounded by a dielectric, which dielectric is surrounded by a conductor layer, includes a connector body having a first end and a second end and a central passageway therethrough; an insulator disposed within the central passageway at the first end of the body; the insulator having an opening therein; a compression sleeve assembly connected to the second end of the body; first clamp means, disposed in the central passageway, for clamping onto the conductor layer; and second clamp means, disposed within the central passageway, for clamping onto the center conductor, whereby upon axial advancement of the compression sleeve assembly from the second end to the first end, the first and second clamp means are radially compressed inwardly. 
     According to an embodiment of the invention, a method for installing a compression connector onto a coaxial cable, wherein the coaxial cable includes a center conductor surrounded by a dielectric, which dielectric is surrounded by a conductor layer, includes the steps of (a) forming a connector body having a first end and a second end, and a central passageway therethrough; (b) forming an insulator for placement within the central passageway at the first end of the body, wherein the insulator includes an opening therein; (c) forming a conductive pin having a collet portion at one end thereof, wherein an outer diameter of the collet portion is greater than a diameter of the opening in the insulator, such that forcing the conductive pin in the longitudinally axial direction causes the outer diameter of the collet portion to reduce in size as the collet portion is forced into the opening; (d) forming a compression sleeve assembly for connection to the second end of the body; (e) forming a clamp and disposing the clamp on an inside of the body, the clamp having a first portion and a second portion, wherein the first portion has an outer engagement surface and the second portion has an outer diameter; (f) forming a mandrel for placement between the clamp and the collet portion; (g) forming a transition member and disposing the transition member between the mandrel and the clamp, wherein the transition member includes a transition surface on an inside of the transition member and a smooth surface on an outside of the transition member such that the transition member and the body make good electrical contact; (h) wherein a diameter of the smooth surface of the transition member and the outer diameter of the second portion of the clamp are the same; (i) wherein forcing the clamp in the longitudinally axial direction causes the outer engagement surface to interact with the transition surface such that the first portion of the clamp reduces inwardly in size; and (j) wherein an axial movement of the compression assembly causes both the clamp and the collet portion to clamp inwardly. 
     The foregoing and other features and advantages of the present invention will be apparent from the following more detailed description of the particular embodiments of the invention, as illustrated in the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  shows a perspective view of a spiral corrugated coaxial cable where an end has been prepared for engagement with a coaxial cable connector. 
         FIG. 1B  shows a perspective view of the spiral corrugated coaxial cable of  FIG. 1A  with the dielectric foam removed. 
         FIG. 1C  shows a perspective view of an annular corrugated coaxial cable where an end has been prepared for engagement with a coaxial cable connector. 
         FIG. 1D  shows a perspective view of a smooth-walled coaxial cable where an end has been prepared for engagement with a coaxial cable connector. 
         FIG. 1E  shows a perspective view of the smooth-walled coaxial cable of  FIG. 1D  with the dielectric foam removed. 
         FIG. 2  shows a perspective view with a partial cut-away of a coaxial cable connector in a partially compressed position in accordance with a first embodiment of the present invention. 
         FIG. 3  shows a cross-section of the coaxial cable connector of  FIG. 2  shown in the installed position. 
         FIG. 4  shows an exploded view of the coaxial cable connector of  FIG. 2 . 
         FIG. 5  shows a perspective view with a partial cut-away of a coaxial cable connector in accordance with a second embodiment of the present invention for use with an annular corrugated coaxial cable. 
         FIG. 6  shows a cross sectional view of a coaxial cable connector in accordance with a variation of the second embodiment of the present invention. 
         FIG. 7  shows an exploded view of the coaxial cable connector of  FIG. 6 . 
         FIG. 8  shows a cross-section of a coaxial cable connector taken along the line  8 - 8  in  FIG. 9  in accordance with a third embodiment of the present invention shown in the uninstalled position. 
         FIG. 9  shows a side elevation view of the coaxial cable connector of  FIG. 8 . 
         FIG. 10  shows an exploded view of the coaxial cable connector of  FIG. 2 . 
         FIG. 11  shows a cross-section of a connector body in accordance with an embodiment of the present invention. 
         FIG. 11A  shows an expanded view of a transitional surface circled in  FIG. 11  in accordance with an embodiment the present invention. 
         FIG. 11B  shows an expanded view of a convex transitional surface circled in  FIG. 11  in accordance with an embodiment the present invention. 
         FIG. 11C  shows an expanded view of a ramped transitional surface circled in  FIG. 11  in accordance with an embodiment the present invention. 
         FIG. 11D  shows an expanded view of a concave transitional surface circled in  FIG. 11  in accordance with an embodiment the present invention. 
         FIG. 12  shows a cross-section of a coaxial cable connector according to an embodiment of the present invention which is similar to the cable connector of  FIG. 8  but intended for installation on a smooth-walled coaxial cable. 
         FIG. 13  shows a partial cross sectional view of a coaxial cable connector in accordance with an embodiment of the present invention. 
         FIG. 14  shows a partial cross sectional view of a coaxial cable connector at a certain stage of compression in accordance with the embodiment of  FIG. 13 . 
         FIG. 15  shows a partial cross sectional view of a coaxial cable connector at a compressed stage in accordance with the embodiment of  FIG. 13 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Referring to  FIG. 1A , a spiral corrugated coaxial cable  10  is shown prepared for installation onto a compression connector  20  ( FIG. 2 ). A jacket  12  is cutaway to expose a portion of a spiral corrugated conductor layer  14 . Layer  14  is also known as the ground or outer conductor layer. Both corrugated conductor layer  14  and a dielectric  16  are cutaway from a center conductor  18 . Preparation of corrugated coaxial cable  10  for installation is well known in the art. 
     Referring to  FIG. 1B , a spiral corrugated coaxial cable  10 ′ is shown prepared for installation onto a compression connector  60  ( FIG. 6 ). In addition to jacket  12  being cutaway to expose a portion of spiral corrugated conductor layer  14 , dielectric  16  is cored out leaving a hollow  58  after both corrugated conductor layer  14  and dielectric  16  are cutaway from center conductor  18 . Preparation of corrugated coaxial cable  10 ′ for installation is well known in the art. 
     Referring to  FIG. 1C , a non-spiral corrugated coaxial cable  10 ″ is shown prepared for installation onto a compression connector. The preparation of cable  10 ″ is well known in the art, and is the same as previously described with respect to  FIG. 1A . Note that corrugated conductor layer  14 ″ is non-spiral, but still corrugated. The basic steps of preparing a corrugated coaxial cable are known in the prior art, such as removing a portion of the cable jacket or coring the dielectric foam. For example, it is known to cut away the corrugated outer conductor in a “valley” to ensure enough of the “peak” is left for outer conductor seizure. However, the present invention allows the outer conductor to be cut in either the “peak” or a “valley” because of the configuration of the inner surface of the outer conductor clamp. 
     Referring to  FIG. 1D , a smooth walled coaxial cable  10 ′″ is shown prepared for installation onto a compression connector. The preparation of cable  10 ′″ is well known in the art, and is the same as previously described with respect to  FIG. 1A . Note that conductor layer  14 ′″ is non-spiral and non-corrugated, i.e., smooth walled. 
     Referring to  FIG. 1E , a smooth walled coaxial cable  10 ″″ is shown prepared for installation onto a compression connector. In addition to jacket  12  being cutaway to expose a portion of conductor layer  14 ″, dielectric  16  ( FIG. 1D ) is cored out leaving a hollow  58  after both conductor layer  14  and dielectric  16  are cutaway from center conductor  18 . Preparation of coaxial cable  10 ″″ for installation is well known in the art. 
     Referring also to  FIG. 2 , compression connector  20 , shown in a partially compressed position, includes a body  22  with a nut  24  connected to body  22  via an annular flange  26 . An insulator  28  positions and holds a conductive pin  30  within body  22 . Conductive pin  30  includes a pin portion  32  at one end and a collet portion  34  at the other end. A drive insulator or mandrel  36  is positioned inside body  22  between and end of collet portion  34  and a clamp  38 . Clamp  38  has an interior annular surface which is geometrically congruent to the spiral of spiral corrugated conductor layer  14 . Clamp  38  preferably includes a plurality of slots  39  ( FIG. 4 ) in an outer annular portion of the clamp, so that clamp  38  can be compressed or squeezed inward. A part of a compression sleeve  40  fits over an end  42  of body  22 . A drive portion  44  of compression sleeve  40  fits against an annular flange  46  of a drive ring  48 . An elastomer seal  50  fits against jacket  12  of corrugated coaxial cable  10  during installation to prevent external environmental influences (moisture, grit, etc.) from entering connector  20  as well as to provide strain relief and increase cable retention. 
     When prepared corrugated coaxial cable  10  is inserted into an opening  54  of connector  20 , cable  10  is twisted as it is inserted so that the spirals on conductor layer  14  fit into the spirals in clamp  38 , while center conductor  18  fits into collet portion  34 . When compressive force is applied to compression sleeve  40  in the direction indicated by an arrow a, drive portion  44  of compression sleeve  40  drives drive ring  48  against clamp  38 , forcing clamp  38  against a transition surface  52  of body  22 , which transition surface  52  is configured to radially inwardly squeeze clamp  38  against conductor layer  14 , while continuing to move clamp  38  axially in the direction of arrow a. Clamp  38  thus forces mandrel  36  to move in the direction of arrow a, and mandrel  36  forces collet portion  34  of conductive pin  30  through an opening  56  in insulator  28 . Opening  56  may take various forms, including convex, concave, or radial. Collet portion  34  also has a collet transition surface  35  configured to compress collet portion  34  radially inwardly upon advancement of conductive pin  30  into opening  56  of insulator  28 . Because a diameter of opening  56  is smaller than an outer diameter ramped surface  35  of collet portion  34 , collet portion  34  is squeezed onto and seizes center conductor  18  of corrugated coaxial cable  10 . During the clamping process, it is noted that center conductor  18 , now located within conductive pin  30 , does not move relative to pin  30  during the clamping process. With the transition surface as shown in  FIG. 2 , the collet portion  34  is simultaneously compressed radially inwardly at the same time clamp  38  is compressed radially inwardly. The transition surface  35  however, can be designed to have a portion of surface  35  consistent with the diameter of opening  56 . In this instance, the squeezing of collet portion  34  is delayed until a greater advancement of compression sleeve  40 . 
       FIG. 3  shows the position of the driven and compressed elements of connector  20  after connector  20  is installed onto corrugated coaxial cable  10 . 
     Referring to  FIG. 4 , an exploded view is shown of the components of connector  20 . During preferred assembly of the components of connector  20 , conductive pin  30  is inserted into insulator  28 , after which the combination is inserted into body  22 , followed by mandrel  36 , clamp  38 , and drive ring  48 . Seal  50  is positioned inside compression sleeve  40 , after which the combination is slid onto/into body  22  after nut  24  is slid over the outside of body  22 . 
     Referring now to  FIGS. 5-6 , and referring back to  FIG. 1B , a compression connector  60  is similar to compression connector  20  of  FIGS. 2-4 , but with a mandrel  76  having an extended portion  98  which fits into hollow  58  of corrugated coaxial cable  10 ′ during installation of connector  60  onto cable  10 ′. Extended portion  98  provides support to the spiral corrugated conductor layer  14  during compression. Another difference between embodiments is that a body  62  of connector  60  is shaped somewhat differently to accommodate an O-ring  100  which provides sealing with a portion  102  of a compression sleeve  80  when connector  60  is installed onto cable  10 ′. The remainder of the components of connector  60  interoperate the same way as the components of the embodiment of connector  20  and are not described further herein. 
     Referring to  FIG. 7 , an exploded view is shown of the components of connector  60 . During preferred assembly, an O-ring  100  is placed onto body  62 . A conductive pin  70  is inserted into insulator  68 , after which the combination is inserted into body  62 , followed by mandrel  76 , a clamp  78 , and a drive ring  88 . A seal  90  is positioned inside compression sleeve  80 , after which the combination is slid onto/into body  62  after nut  64  is slid over the outside of body  62 . During compression, an inner diameter of seal  90  decreases, thus forming a seal around jacket  12 . This provides strain relief on the cable and also aids in cable retention. 
     Referring to  FIGS. 8-10 , a compression connector  110  is shown which is similar to the previous embodiments, but which includes a spacer  112  between a mandrel  114  and a clamp  116 . The addition of spacer  112  may assist in better impedance matching. During installation of connector  110  onto corrugated coaxial cable  10  ( FIG. 1A ), clamp  116  forces spacer  112  against mandrel  114  instead of acting directly against mandrel  114 . It should be obvious to one of ordinary skill in the art that such variations are within the scope of the invention. The remainder of the components of this embodiment interact in the same manner as the previous embodiments, so that further description is omitted. 
     Referring to  FIG. 11 , transition surface  52  may take various forms, including a shoulder, a ramped or tapered surface, or various shapes such as convex, concave or radial.  FIG. 11A  shows a shoulder,  FIG. 11B  shows a convex surface,  FIG. 11C  shows a ramped surface, and  FIG. 11D  shows a concave surface. 
     Referring to  FIG. 12 , a coaxial cable connector  110 ′ is shown which is similar to cable connector  110  ( FIG. 8 ) but which is intended for installation on smooth-walled coaxial cable  10 ′″ ( FIG. 1D ). Note that clamp  116 ′, unlike clamp  116  of  FIG. 8 , does not contain valleys and ridges corresponding to the valleys and ridges of corrugated coaxial cable in order to provide greater gripping surface. 
     Referring to  FIG. 13 , a compression connector  150  is shown in a partially compressed position, while  FIG. 14  shows the same compression connector  150  in a more fully compressed position, and  FIG. 15  shows the same compression connector  150  in a fully compressed position. That is,  FIG. 15  shows the position of the driven and compressed elements of connector  150  after connector  150  is installed onto coaxial cable  10 ,  10 ′,  10 ″,  10 ′″,  10 ″″. 
     Referring to  FIGS. 13-15 , compression connector  150  includes a body  152  with a nut  154  connected to body  152  via an annular flange  156 . An insulator  158  positions and holds a conductive pin  160  within body  152 . Conductive pin  160  includes a pin portion  162  at one end and a collet portion  164  at the other end. A drive insulator or mandrel  166  is positioned inside body  152  between and end of collet portion  164  and a clamp  168 . Clamp  168  optionally has an interior annular surface which is geometrically congruent to the spiral of spiral corrugated conductor layer  14  when connector  150  is to be used with spiral corrugated coaxial cable; otherwise the interior annular surface of clamp  168  is generally smooth. Clamp  168  preferably includes a plurality of slots  139  in an outer annular portion of the clamp, so that clamp  168  can be compressed or squeezed inward. A part of a compression sleeve  170  fits over an end  142  of body  152 . A drive portion  144  of compression sleeve  170  fits against an annular flange  146  of a drive ring  178 . An elastomer seal  190  fits against jacket  12  of coaxial cable  10 , 10 ′, 10 ″, 10 ′″, 10 ″″ during installation to prevent external environmental influences (moisture, grit, etc.) from entering connector  150  as well as to provide strain relief and increase cable retention. 
     Mandrel  166  preferably includes an extended portion  180  which provides support to conductor layer  14 ,  14 ′,  14 ″,  14 ′″ during compression and may assist in better impedance matching than without portion  180 . An annular groove  192  accommodates an O-ring (item  100  in  FIG. 5 ) which provides sealing with a portion  194  of compression sleeve  170  when connector  150  is installed onto cable  10 ,  10 ′,  10 ″,  10 ′″,  10 ″″. 
     Connector  150  preferably includes a transition member  169  which fits inside body  152 , with an outer surface of transition member  169  making good electrical contact with an inner surface of body  152 . The outer surface of transition member  169  is preferably smooth but may be ridged or roughened or otherwise not smooth. A transition surface  196  on an inner surface of transition member  169  cooperates with an outer engagement surface  174  of clamp  168  as connector  150  is fitted onto coaxial cable  10 ,  10 ′,  10 ″,  10 ′″,  10 ″″ to drive clamp  168  radially inward. 
     When prepared coaxial cable  10 ,  10 ′,  10 ″,  10 ′″,  10 ″″ is inserted into an opening  148  of connector  150 , center conductor  18  fits into collet portion  164 . When compressive force is applied to compression sleeve  170  in the direction indicated by an arrow a, drive portion  144  of compression sleeve  170  drives drive ring  178  against clamp  168 , forcing clamp  168  against transition surface  196  of transition member  169 , which transition surface  196  is configured to radially inwardly squeeze clamp  168  against conductor layer  14 ,  14 ′,  14 ″,  14 ′″ while continuing to move clamp  168  axially in the direction of arrow a. Clamp  168  thus forces mandrel  166  to move in the direction of arrow a, and mandrel  166  forces collet portion  164  of conductive pin  160  through an opening  172  in insulator  158 . Opening  172  may take various forms, including convex, concave, or radial. Collet portion  164  also has a collet transition surface  135  configured to compress collet portion  164  radially inwardly upon advancement of conductive pin  160  into opening  172  of insulator  158 . Because a diameter of opening  172  is smaller than an outer diameter of ramped collet transition surface  135  of collet portion  164 , collet portion  164  is squeezed onto and seizes center conductor  18  of coaxial cable  10 ,  10 ′,  10 ″,  10 ′″,  10 ″″. It should be noted that, during the clamping process, center conductor  18 , now located within conductive pin  160 , does not move relative to pin  160  during the clamping process. With the transition surface as shown in  FIGS. 13-15 , collet portion  164  is simultaneously compressed radially inwardly at the same time clamp  168  is compressed radially inwardly. Transition surface  135  however, can be designed to have a portion of surface  135  consistent with the diameter of opening  172 , such that the squeezing of collet portion  164  is delayed until a greater advancement of compression sleeve  170  than is otherwise the case. 
     During installation of any of these embodiments onto spiral corrugated coaxial cable  10  ( FIG. 1A ), non-spiral corrugated coaxial cable  10 ′, and smooth walled coaxial cable  10 ′″, connectors  20 , 60 ,  110 ,  150  have to be relatively immovable while compressive force is applied to the respective compression sleeves in the direction of arrow a ( FIGS. 2 &amp; 13 ). The preferred design of a compression connector tool to accomplish the installation would, while applying the compressive force in the direction of arrow a, stabilize the connector in the opposing direction, thus ensuring that the compressive force was sufficient to squeeze the respective clamps around the conductor layer of the corrugated coaxial cable and squeeze the respective collet portions onto the center conductor. Although the squeezing of the respective clamps begins slightly before the squeezing of the respective collet portions, the squeezing of the respective clamps and collet portions mainly happens simultaneously, unlike with prior art embodiments which require a two-stage operation. 
     While the present invention has been described with reference to a particular preferred embodiment and the accompanying drawings, it will be understood by those skilled in the art that the invention is not limited to the preferred embodiment and that various modifications and the like could be made thereto without departing from the scope of the invention as defined in the following claims.