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, or second clamp, which seizes a center conductor of the coaxial cable. The connector also includes a first clamp disposed inside the body as well as a compression sleeve assembly. The body includes a transitional surface separating the body into two regions of different inside diameter. When an axial force is applied to the compression sleeve, the clamp is forced by the transitional surface into the body region having a smaller diameter, 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, causing the collet portion to squeeze onto the center conductor.

Description:
FIELD OF THE INVENTION 
       [0001]    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. 
       BACKGROUND OF THE INVENTION 
       [0002]    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. 
         [0003]    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 (wwv.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. 
         [0004]    When affixing a cable connector to a corrugated 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 OF THE INVENTION 
       [0005]    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. The body includes a transitional surface separating the body into two regions of different inside diameter. When an axial force is applied to the compression sleeve, the clamp is forced by the transitional surface into the body region having a smaller diameter, 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. 
         [0006]    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. 
         [0007]    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) providing a connector body having a first end and a second end and a central passageway therethrough; (b) providing an insulator disposed within the central passageway at the first end of the body; (c) providing an opening within the insulator; (d) connecting a compression sleeve assembly to the second end of the body; (e) providing a first clamp for clamping onto the conductor layer, the first clamp being disposed in the central passageway; (f) providing a second clamp for clamping onto the center conductor, the second clamp being disposed in the central passageway; and (g) transmitting a force in a longitudinally axial direction of the body from the compression sleeve assembly to both the first and second clamps, wherein an axial movement of the compression sleeve assembly from the second end to the first end causes both the first and second clamps to radially compress inwardly. 
         [0008]    According to an embodiment of the invention, a method for manufacturing 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 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 compression sleeve assembly for connection to the second end of the body; (d) forming a clamp having an outer diameter and a transition surface disposed on an inside of the body; wherein the shoulder separates the body into a first portion having a first inner diameter and a second portion having a second inner diameter; wherein the outer diameter of the clamp is substantially the same as the first inner diameter, but greater than the second inner diameter; and wherein forcing the clamp in the longitudinally axial direction causes the outer diameter of the clamp to reduce in size as the clamp is forced from the first portion of the body to the second portion of the body; and (e) 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, wherein an axial movement of the compression assembly causes both the clamp and the collet portion to clamp inwardly. 
         [0009]    According to an embodiment of the invention, a connector for coupling an end of a coaxial cable, the coaxial cable having a center conductor surrounded by a dielectric and the dielectric surrounded by a conductor layer, includes a connector body having a first end and a second end, the connector body extending along a longitudinal axis and having defined therein an internal passageway, the first end having a first outer diameter and a first inner diameter; a first clamp positioned within the first inner diameter and having a first clamp central passageway configured for receiving the conductor layer, the first clamp further having an outer surface for engagement with a first surface on the central passageway configured to radially inwardly compress the first clamp; an insulator axially positioned within the second end of the connector body and having an insulator passageway; a second clamp assembly positioned along the longitudinal axis of the connector body between the first clamp and the insulator and having a second clamp central passageway for receiving the center conductor; the second clamp assembly having a surface portion extending into the insulator passageway; and a compression assembly positioned at the first end of the connector body for engagement with the first clamp, the compression assembly having a compression assembly passageway for receiving the coaxial cable, wherein axial advancement of the compression assembly moves the first clamp member toward the first surface to compress the first clamp radially inwardly to engage the conductor layer of the coaxial cable, and wherein further axial advancement of the compression assembly moves the second clamp assembly surface portion towards the insulator passageway, whereby the second clamp central passageway is radially inwardly compressed to engage the center conductor of the coaxial cable. 
         [0010]    According to an embodiment of the invention, a connector for coupling an end of a coaxial cable, the coaxial cable having a center conductor surrounded by a dielectric and the dielectric surrounded by an outer conductor, includes a connector body extending along a longitudinal axis, the connector body having defined therein a connector body central passageway, the connector body having a first end and a second end, the first end having a first end internal diameter and a first end outer diameter; a compression member assembly configured to axially slidably engage the first end outer diameter; a first clamp located within the connector body passageway, the first clamp having a first clamp central passageway, the first clamp central passageway having an internal surface configured to receive the outer conductor of the coaxial cable; a mandrel located within the connector body central passageway for engagement with the first clamp, the mandrel configured to receive the center conductor; a second clamp located within the connector body central passageway, the second clamp having a second clamp central passageway configured to receive the center conductor; and an insulator located within the connector body central passageway, the insulator configured to receive a portion of the second clamp, wherein axial advancement of the compression member assembly along the longitudinal axis of the connector body compresses the first clamp radially inwardly to engage the outer conductor, and wherein further axial advancement of the compression member assembly along the longitudinal axis of the connector body causes movement of the mandrel toward the second clamp, whereby the insulator receives a portion of the second clamp which compresses the second clamp radially inwardly to engage the center conductor. 
         [0011]    According to an embodiment of the invention, a method of attaching a connector having an internal passageway to a coaxial cable, the coaxial cable having a center conductor surrounded by an outer conductor, and wherein the connector includes a first clamp, a second clamp, a mandrel and an insulator located within the internal passageway, includes the steps of (a) inserting an end of the coaxial cable into the connector; (b) threading the outer conductor of the coaxial cable into the first clamp of the connector; (c) inserting the center conductor of the coaxial cable into the mandrel and the second clamp; (d) axially advancing the first clamp along a longitudinal axis of the connector body to compress the first clamp radially inwardly to engage the outer conductor; and (e) axially advancing the first clamp further to cause axial movement of the mandrel to advance the second clamp toward the insulator to compress the second clamp radially inwardly to engage the center conductor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      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. 
           [0013]      FIG. 1B  shows a perspective view of the spiral corrugated coaxial cable of  FIG. 1A  with the dielectric foam removed. 
           [0014]      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. 
           [0015]      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. 
           [0016]      FIG. 1E  shows a perspective view of the smooth-walled coaxial cable of  FIG. 1D  with the dielectric foam removed. 
           [0017]      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. 
           [0018]      FIG. 3  shows a cross-section of the coaxial cable connector of  FIG. 2  shown in the installed position. 
           [0019]      FIG. 4  shows an exploded view of the coaxial cable connector of  FIG. 2 . 
           [0020]      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. 
           [0021]      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. 
           [0022]      FIG. 7  shows an exploded view of the coaxial cable connector of  FIG. 6 . 
           [0023]      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. 
           [0024]      FIG. 9  shows a side elevation view of the coaxial cable connector of  FIG. 8 . 
           [0025]      FIG. 10  shows an exploded view of the coaxial cable connector of  FIG. 2 . 
           [0026]      FIG. 11  shows a cross-section of a connector body in accordance with an embodiment of the present invention. 
           [0027]      FIG. 11A  shows an expanded view of a transitional surface circled in  FIG. 11  in accordance with an embodiment the present invention. 
           [0028]      FIG. 11B  shows an expanded view of a convex transitional surface circled in  FIG. 11  in accordance with an embodiment the present invention. 
           [0029]      FIG. 11C  shows an expanded view of a ramped transitional surface circled in  FIG. 11  in accordance with an embodiment the present invention. 
           [0030]      FIG. 11D  shows an expanded view of a concave transitional surface circled in  FIG. 11  in accordance with an embodiment the present invention. 
           [0031]      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. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0032]    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. 
         [0033]    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. 
         [0034]    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. 
         [0035]    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. 
         [0036]    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. 
         [0037]    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. 
         [0038]    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 . 
         [0039]      FIG. 3  shows the position of the driven and compressed elements of connector  20  after connector  20  is installed onto corrugated coaxial cable  10 . 
         [0040]    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 . 
         [0041]    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. 
         [0042]    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. 
         [0043]    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. 
         [0044]    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. 
         [0045]    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. 
         [0046]    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  have to be relatively immovable while compressive force is applied to the respective compression sleeves in the direction of arrow a ( FIG. 2 ). 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. 
         [0047]    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.