Patent Publication Number: US-2005136735-A1

Title: Coaxial connector having improved locking sleeve

Description:
FIELD OF THE INVENTION  
      The present invention relates generally to connectors for terminating coaxial cable. More particularly, the present invention relates to a connector having a locking sleeve that requires decreased insertion force to terminate a coaxial cable to a connector body.  
     BACKGROUND OF THE INVENTION  
      It has long been known to use connectors to terminate coaxial cable so as to connect a cable to various electronic devices such as televisions, radios and the like.  
      Conventional coaxial cables typically include a center conductor surrounded by an insulator. A braided or foil conductive shield is disposed over the insulator. An outer insulative jacket surrounds the shield. In order to prepare the coaxial cable for termination, the outer jacket is stripped back exposing an extent of the conductive shield which is folded back over the jacket. A portion of the insulator extends outwardly from the jacket and an extent of the center conductor extends outwardly from insulator. Such a prepared cable may be terminated in a conventional coaxial connector.  
      Coaxial connectors of this type include a connector body having an inner cylindrical post that is inserted between the insulator and the conductive shield. A locking sleeve is provided to secure the cable within the body of the coaxial connector. The locking sleeve, which is typically formed of a resilient plastic, is securable to the connector body to affix the coaxial connector thereto. A leading coaxial connector of this type is shown and described in U.S. Pat. No. 6,530,807 that is assigned to Thomas &amp; Betts Corporation (headquartered at 8155 T&amp;B Blvd, Memphis, Tenn. 38125, U.S.A.) and entitled: “Coaxial connector having detachable locking sleeve.” 
      Coaxial connectors of this type employ a uniform annular ring that is integrally formed on the outside of the locking sleeve for detachably locking the sleeve to the connector body once a coaxial cable is inserted therethrough. Since the annular ring is slightly larger than the collar of the connector body, compression force must be used to insert the locking sleeve and cable into the collar of the connector body. During insertion, the collar compresses the ring&#39;s diameter because the collar is of a harder material than the locking sleeve. Once the uniform annular ring is seated within the collar, its diameter expands back to its original size and form, thereby locking the sleeve to the collar. Since the ring spans 360° around the outside of the locking sleeve, it requires sufficient force, which is typically applied by a tool, to terminate a cable in the connector by inserting the locking sleeve within the connector body.  
      It is therefore desirable to provide an improved coaxial connector having an improved locking sleeve that decreases the compression force required for insertion of the sleeve into the connector body while suffering no loss in locking capabilities, structural integrity, RFI performance, or water loss migration. It is further desirable to reduce stresses applied to the locking sleeve during insertion into and removal from the connector body.  
     SUMMARY OF THE INVENTION  
      The present invention eliminates the above difficulties and disadvantages by providing a coaxial connector having a locking sleeve with low compression force for inserting into the connector body. In particular, the present locking sleeve includes at least one protrusion, but preferably a plurality of protrusions formed on the locking sleeve, which are spaced about the locking sleeve and preferably evenly spaced. The connector includes a connector body having an annular detent disposed therein and a locking sleeve detachably coupled to the connector body. The protrusions are received in the detent, which is preferably annular, when the coaxial cable is terminated in the connector while suffering no loss in locking capabilities, structural integrity, RFI performance, or water loss migration. The protrusions include a chamfered front wall for easing insertion into the detent, which has a complementary and chamfered wall for receiving the front wall of the protrusions. The protrusions also include a perpendicular rear wall and the detent includes a forwardly facing perpendicular wall for abutting the perpendicular rear wall of the protrusions and preventing extraction of the protrusions from the detent. In addition, the protrusions are of greater malleable composition than the connector body and preferably constructed of plastic with the connector body being formed of metal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an exploded perspective view showing of the coaxial connector of the present invention including a connector body and a detachably coupled locking sleeve.  
       FIG. 2  is a perspective view of the coaxial connector of the present invention including the connector body and the detachably coupled locking sleeve of  FIG. 1 .  
       FIG. 3  is a cross-sectional view of the coaxial connector of the present invention including the connector body and the detachably coupled locking sleeve of  FIG. 1 .  
       FIG. 4  is an exploded cross-sectional view of the coaxial connector of the present invention including a connector body and a detachably coupled locking sleeve of  FIG. 1  showing a coaxial cable being inserted into the connector.  
       FIG. 5  is a partial cross-sectional view of the locking sleeve inserted into the coaxial connector of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The present invention is directed to connectors for terminating coaxial cable. Coaxial connectors of this type are shown and described in U.S. Pat. No. 6,530,807 issued Mar. 11, 2003, which is incorporated by reference herein for all purposes.  
      Referring first to  FIGS. 1-3 , the coaxial cable connector  10  of the present invention is shown. Connector  10  includes two major components, a connector body  12  and a locking sleeve  14  attachably coupled to body  12 . Body  12  is an elongate generally cylindrical conductive member typically formed of metal, preferably brass. Body  12  includes an annular collar  16  for accommodating a coaxial cable, an annular nut  18  rotatably coupled to collar  16  for providing mechanical attachment of the connector to an external device. Interposed between collar  16  and nut  18  is an annular post  20 . A resilient sealing O-ring  22  may be positioned between collar  16  and nut  18  at the rotatable juncture thereof to provide a seal thereat. Nut  18  includes an internally threaded end extent  26  permitting screw threaded attachment of body  12  to the external device. Annular post  20  includes a base portion  28  which provides for securement of post  20  between nut  18  and collar  16  and an annular tubular extension  30  extending into collar  18 . As will be described in further detail hereinbelow and as is conventionally known, the extension  30  of post  20  and the collar  16  define an annular chamber  32  for accommodating the jacket and shield of the inserted coaxial cable.  
      Locking sleeve  14  is a generally cylindrical member formed of resilient material preferably a synthetic plastic such as an acetate resin. Locking sleeve  14  includes a flared rearward end  34  through which a cable may be inserted. Opposite rearward end  34  is a forward end  36  which is insertable into locking sleeve  14 . As will be described in further detail hereinbelow, the forward end  36  of locking sleeve  14  includes cooperative detent structure which allows for the detachable, re-attachable connection of locking sleeve  14  to body  12 . Furthermore, connector  10  is designed such that locking sleeve  14  is axially moveable along arrow A of  FIG. 2 , towards nut  18  from a first position shown in  FIG. 2 , which loosely retains the cable within connector body  12  through an intermediate position, to a more forward second position shown in  FIG. 5 , which secures the cable within connector body  12 .  
      Connector  10  of the present invention is constructed so as to be supplied in the assembled condition shown in  FIG. 3 . In such assembled condition, and as will be described in further detail hereinbelow, a coaxial cable may be inserted through the rearward end  34  of locking sleeve  14  and through connector body  12 . The locking sleeve may be moved from the first position loosely retaining the cable to the second position which is axially forward thereby locking the cable to the connector body. It is, however, contemplated that the locking sleeve  14  may be detached from connector body  12  and in a manner which will be described in further detail hereinbelow, so as to allow the coaxial cable to be inserted directly into receiving end  24  of connector body  12 . Thereafter, the locking sleeve  14  which has been placed around the cable may be reattached to receiving end  24  of body  12  where it can be moved from the first position to the second position locking the cable to the connector body.  
      The cooperating detent structure mentioned above, is employed to provide such detachment and reattachment of locking sleeve  14  to connector body  12 . The cooperating detent structure of the present invention further includes the forward end  36  of locking sleeve  14 . As may be appreciated, the forward end  36  of locking sleeve  14  may be inserted into the receiving end  24  of collar  16 . This defines the first position of locking sleeve  14 . While the locking sleeve is accommodated in collar  16  it may be detachable and such removal is facilitated by the resiliency of the plastic material forming locking sleeve  14  and relative thickness of the sleeve wall thereat. In particular, the protrusions  54  of the locking sleeve  14  are of greater malleable composition, as well as the locking sleeve  14 , than the connector body  12 , which is preferably constructed of metal such as brass with the protrusions  14  being formed of plastic along with the locking sleeve  14 . In an alternate embodiment, however, the connector body  12  and locking sleeve are both formed of the same material with only the protrusions  54  being of a material such as plastic or rubber that is of greater malleable composition than the connector body  12 . In this regard, connector body  12  can also be constructed of plastic, and preferably a thermoformed plastic such as acetate resin.  
      As shown in  FIGS. 1-5 , the cooperative detent structure includes at least one radially outwardly extending protrusion  54  adjacent rearward end  34  of sleeve  14 , but preferably a plurality of protrusions  54  as will be discussed in greater detail below. The protrusions  54  allow the locking sleeve  14  to be inserted into the connector body  12  with low compression force to terminate cable  60  within connector body  12  while the connector  10  suffers no loss in locking capabilities, structural integrity, RFI performance, or water loss migration. In particular, the present locking sleeve includes at least one protrusion  54 , but preferably a plurality of protrusions  54  formed on the locking sleeve  14 , which are spaced about the locking sleeve  14  and preferably evenly spaced around the outer circumference. The protrusions  54  are received in detent  58 , which is preferably annular, when the coaxial cable  60  is terminated in the connector  10 . Upon continued coaxial movement along arrow A, as shown in  FIGS. 2 and 5 , protrusions  54  engage detent  58  that locks cable  60  to connector body  12  in the second position as shown in  FIG. 5 . Since detent  58  is uniform and preferably annular, it does not matter how the protrusions  54  are oriented in a circumferential direction when locking sleeve  14  is inserted into the second position within the connector body  12 .  
      As further shown in  FIG. 5 , each of the protrusions  54  include a chamfered front wall  54   a , which is preferably formed at a forty-five degree angle, for easing insertion into detent  58 , which has a complementary and chamfered wall  44  for receiving the front wall  54   a  of the protrusions  54 . The protrusions  54  also include a perpendicular rear wall  54   b  and detent  58  includes a forwardly facing perpendicular wall  42  for abutting the perpendicular rear wall  54   b  of the protrusions  54  and preventing extraction of the protrusions from detent  58 .  
      Referring now to  FIGS. 6-8 , an alternate embodiment of the present invention is shown. In this embodiment the locking sleeve  14  is coupled to the connector body  12  and has at least one groove  70  formed therein, which is preferably U-shaped. The groove  70  is preferably continuous, but can also be annularly spaced apart apertures. An O-ring  55 , preferably made of resilient rubber, is disposed about the locking sleeve  14  for sealing the locking sleeve  14  to the connector body  12  when the locking sleeve  14  is in the second position. Between the O-ring  55  and groove  70  is disposed a retention wall  72  for keeping the O-ring  55  in place when the locking sleeve  14  is moved to the second position.  
      In this embodiment projection  74  is annular and frictionally slides along the smooth outer wall of locking sleeve  14  is received into groove  70  when the locking sleeve  14  is inserted into the connector body  12 , as shown in  FIG. 8 , and the cable  60  is terminated therein. An important advantage of this embodiment is that there is no protrusion or rib disposed on the outer surface of locking sleeve  14  that must be compressed by projection  74  when the locking sleeve  14  is secured to the connector body  12 , which further reduces the axial compression forced needed to be applied to the locking sleeve  14  by an installer.  
      Projection  74  is preferably constructed of metal, such as brass, and integrally formed within connector body  12 , but can also be constructed of plastic. It can further be constructed of rubber and employed as an O-ring. The frictional engagement of projection  74  against the outer surface of the locking sleeve  14  is slight and instead of the projection having to compress the locking sleeve  14  at the points where the protrusions  54  are annularly disposed in the prior embodiment discussed above, projection  74  is received into groove  70  and minimal inward compression of locking sleeve  14  is required.  
      Once in the second position, projection  74  is received in groove  70 , securing the locking sleeve to the connector body  12  in the following fashion. Projection  74  includes a perpendicular wall  42  and a chamfered wall  78  opposite perpendicular wall  76 . At this time O-ring  55  is compressed among the flared rearward end  34  of the locking sleeve  14 , the projection  74  and the retention wall  72  when the locking sleeve  14  is moved to the second position. The perpendicular wall  76  prevents removal of the locking sleeve  14  from the connector body  12  when in the second position.  
      Having described the components of connector  10  in detail, the use of connector  10  in terminating a coaxial cable may now be described with respect to  FIG. 4 . Coaxial cable  60  includes an elongate inner conductor  62  formed of copper or similar conductive material. Extending around inner conductor  62  is a conductor insulator  64  formed of a suitably insulative plastic. A metallic shield  66  is positioned in surrounding relationship around insulator  64 . Shield  66  is a metallic braid, however, other conductive materials such as metallic foil may also be employed. Covering shield  66  is an outer insulative jacket  68 .  
      Cable  60  is prepared in conventional fashion for termination, by stripping back jacket  68  exposing an extent of shield  66 . A portion of insulator  64  extends therefrom with an extent of conductor  62  extending from insulator  64 . The preparation process includes folding back an end extent of shield  66  about jacket  68 .  
      Cable  60  may be inserted into connector  10  with the locking sleeve  14  coupled to collar  16  of body  12  as shown in  FIGS. 2 and 3 . In this technique, the prepared cable  60  is inserted through rearward end  34  of sleeve  14  and into the receiving end  24  of collar  16 . Extension  30  of post  20  of body  12  is inserted between the insulator  64  in the metallic shield  66  such that the shield and the jacket  68  reside within the annular region  32  defined between post  20  and collar  16 . In this position, the locking sleeve is coupled to collar  16  in the first position shown in  FIGS. 2 and 3 . In such first position, sufficient clearance is provided between sleeve  14  and collar  16  so that extension  30  may easily be interposed between insulator  64  and shield  66 .  
      Once the cable  60  is properly inserted, the locking sleeve  14  may be moved from the first position shown in  FIG. 4 , to an intermediate position shown in  FIG. 5 , where the locking sleeve is moved axially forward. Such movement is facilitated by the chamfered wall  44  of receiving end  24  of collar  16 . In this second position, jacket  68  and shield  66  of cable  60  begins to become compressively clamped within annular region  32  between post  20  and collar  16 . The sleeve  14  is further axially advanced along arrow A from the intermediate position to a second position shown in  FIG. 5 . Such second position is achieved as protrusions  54  are disposed within detent  58  of collar  16 . In that regard and discussed in further detail above, protrusions  54  have a forwardly chamfered front wall  54   a  for engagement with chamfered wall  44  of detent  58  to facilitate such resilient movement. Further, the rear wall  54   b  of protrusions  54  is perpendicular so as to engage perpendicular wall  42  of detent  58  to maintain sleeve  14  in the second position with respect to collar  16 . A suitable tool may be used to effect movement of locking sleeve  14  from its first position to its second position securing cable  60  to connector body  12 .  
      It is contemplated that the engagement between insulative jacket  68  and the connector body  12  establishes a sealed engagement thereat. In order to further facilitate the seal, locking sleeve  14  may optionally support a sealing O-ring  55  which provides a seal with the chamfered wall  44  of collar  16  in the second position.  
      Proper insertion of cable  60  into connector body  12  requires that the cable be inserted in such a manner that the extension  30  of post  20  becomes resident between insulator  64  and shield  66 . In certain installation settings, the installer may not have clear and convenient access when terminating cable  60 . Moreover, insertion may be rendered difficult by poor cable preparation, which may result in a frayed end. Therefore, it may be difficult for the installer to blindly insert the cable  60  through the locking sleeve  14  and into connector body  12 . In such situations, the present invention contemplates the ability to detachably remove locking sleeve  14  from connector body  12  so that the cable may be directly inserted to receiving end  24  of collar  16 . In these situations, locking sleeve  14  is detachably removed from collar  16  in a manner facilitated as above described. The locking sleeve  14  is then slipped over cable  60  and moved to a convenient position along the cable length. The end of cable  60  may then be inserted directly into the rearward end  34  of collar  16  to easily assure that extension  30  of post  20  is inserted between insulator  64  and shield  66 . Thereafter, the locking sleeve  14  may be brought up along the cable and the forward end  36  of locking sleeve  14  may be inserted into the rearward end  34  of collar  16 . Thereafter, as described above, the locking sleeve may be moved from the first position shown in  FIG. 2  to a second position shown in  FIG. 5  where the protrusions  54  become resident forward of perpendicular wall  42  thereby locking cable  60  in connector body  12 .  
      Various changes to the foregoing described and shown structures will now be evident to those skilled in the art. Accordingly, the particularly disclosed scope of the invention is set forth in the following claims.