Abstract:
A compression connector suitable for mounting upon the prepared end of a coaxial cable. The connector contains a body that defines an internal cavity made up of a main body section and a break away end section that is integrally joined to the main body section by axially extended tabs. The tabs are arranged to telescope inside the main body section when a sufficient axial force is applied to the body. A post is mounted inside the body and is arranged to pass between the inner dielectric layer and the woven mesh shield of a coaxial cable that is inserted into the body through the break away end section. The telescoped end section co-acts with the post to radially compress the cable in tight frictional engagement.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application is a continuation-in-part of U.S. Ser. No. 10/309,677, filed Dec. 4, 2002 now U.S. Pat. No. 6,780,052. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to connectors for installation on a terminal end of a coaxial cable as used, for example, in CATV applications by radial compression of the cable by a deformable body portion of the connector. More specifically, the invention relates to compression-type connectors wherein the number of parts is reduced and manner of effecting compression is different from conventional, prior art connectors of this type. 
   A common type of connector installed on a terminal end of a coaxial cable includes elements known as a post, a nut, a body and a compression ring. The post includes a hollow stem integrally joined at one end to a flange. The nut is rotatably secured to the post, typically at or near the junction of the stem and flange, and the body surrounds the stem with a first portion, near the nut, in frictional engagement therewith and a second portion in outwardly spaced relation thereto. The compression ring, a hollow, substantially cylindrical member, is initially maintained in engagement with the body by one end of the ring encircling the end of the body remote from the nut. The end of the coaxial cable is prepared by stripping away certain layers thereof at specified distances from the end of the central conductor. After the cable is “prepped” the connector is installed by inserting the cable axially into the connector with the stem of the connector post being forced between the outer layer of conducting material and the woven mesh metallic shielding layer. The shielding layer and the outer dielectric layer are in the initially open, annular space between the stem and inner surface of the body. Installation is completed by axial movement of the compression ring over the body with tapered surfaces on one or both of these members causing radial compression of the body into tight, frictional engagement with the outer surface of the coaxial cable. 
   The prior art includes, of course, a wide variety of styles and configurations of compression connectors of this general type. A feature common to radial compression connectors, however, is the separate fabrication of the body and compression ring which provide the means of frictionally engaging the connector with the cable. A variation of this design is disclosed in U.S. Pat. No. 5,525,076 of Down wherein the connector body includes one or more grooves extending into and around its outer surface. As the body is axially compressed, a portion of the body wall at the groove(s) is forced radially inwardly, into the outer dielectric layer of the coaxial cable. This forms a moisture barrier around the surface of the cable and mechanically locks the connector and cable, but does not radially compress the body into tight frictional engagement with the cable in the manner of the prior art connectors alluded to above and the present invention. 
   It is a principal object of the present invention to provide a novel and improved coaxial cable connector of the radial compression type which requires fewer parts than typical prior art connectors of the same general type, thereby offering advantages normally associated with a reduction in part count of multi-element devices. 
   It is a further object to provide a connector which is mounted to an end portion of a coaxial cable by a novel method of operation. 
   It is another object to provide novel and improved means for mounting a connector to the end of a coaxial cable. 
   Other objects will in part be obvious and will in part appear hereinafter. 
   SUMMARY OF THE INVENTION 
   In furtherance of the foregoing objects, the invention contemplates a connector having an essentially conventional post and nut in combination with a novel body. The post has the usual, integral flange and stem portions and the nut is rotatably engaged with the post at the flanged end. The hollow body includes a first portion extending axially from a first end and having an inner diameter substantially corresponding to the outer diameter of the post stem, a second portion extending axially from the first portion and having a larger inner diameter, and a third portion extending axially from the second portion to a second end. The three portions are integrally formed as a single, molded part. In a first disclosed embodiment, the third portion is connected to the second portion by a wall section of reduced thickness. The third portion is of the same inner diameter as the second portion and tapers to a larger outer diameter from the position of smallest wall thickness toward the second end of the body. When the connector is installed on the cable, the stem extends between the metal shielding layer of the cable and the outer conducting layer in the usual manner with these two layers positioned in the spaced between the outside of the stem and inside of the second body portion. When an axial force is applied (by an appropriate tool) to the third body portion, tending to move it in the direction of the first portion, the wall fractures at the section of smallest thickness, allowing the third section to be forced between the second section and the outer surface of the coaxial cable. The tapered surface on the third section is wedged between the second section and the cable surface, thereby radially compressing the cable and causing tight frictional engagement of the connector and cable. 
   In a second embodiment, the third section of the body has two annular areas of reduced cross section, axially spaced from one another. The thickness of these sections is such, relative to the type and characteristics of the material from which the body is fabricated, that as axial force is applied to the third section, tending to move it in the direction of the second section, that the wall folds at both areas of reduced cross section. Thus, rather than fracturing the body wall, as in the first embodiment, the body remains in a single part, but with folded layers of the third body portion between the inner surface of the second body portion and the outer surface of the cable, producing tight frictional engagement of the connector and the cable. 
   In a third embodiment of the invention, the body of the connector is provided with a weakened end section that is adapted to break away from the main body section and telescope inside the main body section when an axial disposed force is applied to the body. The weakened end section is attached to the main body section by a series of circumferentially spaced apart tabs that taper down from the tab root toward the main body section thereby minimizing the amount of material joining the two sections and thus the amount of axial force required to telescope the weakened end section into the main body section of the connector. 
   The features of the invention generally described above will be more readily apparent and fully appreciated from the following detailed description, taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded, perspective view of the cable connector of the invention, shown in a first embodiment; 
       FIG. 2  is a front elevational view of one of the elements of  FIG. 1  in full section; 
       FIG. 3  is a front elevational view of the connector of  FIG. 1  mounted to a conventional coaxial cable with portions of both the connector and cable broken away to be seen in section; 
       FIG. 4  is an exploded, perspective view of the cable connector of the invention, shown in a second embodiment; 
       FIG. 5  is a front elevational view of one of the elements of  FIG. 4  in full section; 
       FIG. 6  is a front elevational view of the connector of  FIG. 4  mounted to a conventional coaxial cable with portions of both the connector and cable broken away to be seen in section; 
       FIG. 7  is an exploded view in perspective illustrating a further embodiment of the invention; 
       FIG. 8  is a side elevational view in section illustrating the body of the connector shown in  FIG. 7 . 
       FIG. 9  is an enlarged perspective view showing the weakened end section of the body broken away from the body; and 
       FIG. 10  is a side view in partial section of the connector shown in  FIG. 7  illustrating the weakened end section telescoped inside the body. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to the drawings, in  FIG. 1  are shown the three components of the connector, namely, post  10 , including integrally formed flange  12  and stem  14  sections, nut  16  and body  18 . Post  10  and nut  16  are of conventional construction for use in this type of coaxial cable connector, body  18  being of unique construction, shown in a first embodiment in  FIGS. 1–3 . Body  18  is shown in cross section in  FIG. 2  where it will be noted that the body includes three sections, integrally formed as a single piece. The first section  20  extends axially from one end  22  of body  18  for a portion of its axial length having inner diameter D 1 . Second section  24  includes tapered portion  26 , connecting inner diameter D 1  with larger inner diameter D 2  of constant diameter portion  28  second section  24 . Third section  30  extends integrally from second section  24  with the same inner diameter, but with a wall portion  32  of reduced thickness. The smallest thickness of wall portion  32  is at its juncture with second section  24 , denoted by reference numeral  34 , from which the outer surface of third section  30  tapers outwardly at a relatively small angle to wall portion  36  which has the same outer diameter as second section  24  and extends to the outer end  38  of body  18 . The three parts of the connector are mutually assembled by passing stem  14  through the opening defined by internal flange  17  (see  FIG. 3 ) of nut  16 , followed by passing the stem through first section  20  of body  18  until end  22  abuts larger diameter portion  15  of stem  14 . Flange  17  is thus axially engaged between flange  12  of post  10  and end  22  of body  18  with nut  16  being freely rotatable with respect to post  10  and body  18 . 
   The connector is shown in  FIG. 3  in assembled relation with an end portion of a conventional coaxial cable, denoted generally by reference numeral  40  and having inner conductor  42  surrounded by inner layer  44  of dielectric material, layer  46  of conducting material, shielding layer  48  in woven mesh form, and outer layer  50  of dielectric material. After the end of the cable has been prepped in the specified (conventional) manner, it is inserted axially into end  38  of body  18  and advanced until the exposed end surfaces of layers  44  and  46  are substantially flush with the end surface of flange  12 . During this relative movement of the cable and connector, stem  14  is forcibly inserted between cable layers  46  and  48 , as is also conventional in the mounting off connectors upon coaxial cables. The connector is then engaged by a compression tool (not shown) in order to apply an axial force tending to move second and third section  24  and  30  in opposite directions, i.e., toward one another. Upon application of sufficient force in this manner, body  18  fractures about its periphery at the smallest thickness of wall section  32 , i.e., at the juncture of second and third sections  24  and  30 , respectively, denoted in  FIG. 2  by reference numeral  34 . After fracturing, body  18  is in two pieces and continued application of axial force moves wall portion  32  between the inner surface of second section  24  and the outer surface of cable dielectric layer  50 . The outward taper of the outer surface of wall portion  32  results in radial compression of cable  40  and tight frictional engagement of the connector and cable, as shown in  FIG. 3 . 
   Turning now to  FIGS. 4–6 , the connector is shown with a second embodiment of the body, denoted by reference numeral  52 , in combination with the conventional post and nut, here denoted by numerals  10 ′ and  16 ′, respectively. Body  52 , as best seen in the sectional view of  FIG. 5 , again includes first section  54 , extending from one end  56  of the body for the axial length thereof having inner diameter D 1 , second section  58 , having tapered inner surface portion  60  connecting diameter D 1  with larger inner diameter D 2  of constant diameter portion  62  of second section  58 . In this embodiment, third section  64  includes first, second and third wall portions  66 ,  68  and  70 , respectively. First portion  66  extends from the junction of second and third sections  58  and  64 , respectively, at a first area  72  of reduced thickness, tapering outwardly to its juncture with second portion  68  at a second area  74  of reduced thickness. Second portion  68  tapers outwardly to its junction with third portion  70  which extends to the other end  76  of body  52 . Third section  64  is of constant inner diameter D 2  throughout its length and is of smaller outer diameter over both portions  66  and  68  than second section  58 , the outer diameter of third wall portion  70  being equal to that of second section  58 . 
   Body  52  differs from body  18  not only in the use of an additional wall portion in the third section, but also in the material used and the manner of operation. Body  18  is preferably of a quite rigid plastic which also exhibits a degree of brittleness, whereby the material fractures at the peripheral line of smallest thickness and axial movement of the tapered portion between the second body portion and the cable radially compresses the cable with little if any outward radial movement of the body. Body  52 , on the other hand, is made of a more flexible, elastic material. When axial force is applied with a compression tool, rather than fracturing, first wall portion  66  folds inwardly about the periphery of reduced thickness area  72 , causing the periphery at reduced thickness area  74  to move in the direction of arrows  78 . After movement of portion  66  substantially 180°, into contact with the inner surface of second section  58 , wall section  68  has moved into surface-to-surface contact with wall section  66 , as shown in  FIG. 6  which also includes the coaxial cable with common reference numerals denoting the same parts thereof as in  FIG. 3 . The axial force producing the folding action of wall portions  66  and  68  is applied, of course, after the cable has been inserted into the connector. Consequently, the outer surface of the cable stands in the way of the inner movement of wall section  66 , as indicated by arrows  78  in  FIG. 5 . The flexible nature of body  52  permits outward, flexing movement of second section  58  as inward movement of section  66  begins and inward contraction thereof as the folding is completed. The combined thickness of wall sections  66  and  68  inserted into the connector body  52  produces a tight frictional engagement of the connector to the cable. The thickness in areas  72  and  74  are established as a function of the properties of the material of body  52  to provide the desired folding action upon application of axial force tending to move third section  64  toward second section  58 . 
   Turning now to  FIGS. 7–10  there is illustrated a further embodiment of the invention. Here again the compression connector, generally referenced  150  includes a cylindrical hollow body  152 , a post  154  and an internally threaded nut  156 . As best illustrated in  FIGS. 7 and 10 , the post, which is a hollow cylindrical member, contains a shank  157  having a flanged end  155  upon which the nut is rotatably supported in assembly. The shank of the post passes into one end  158  of the body so that the bottom of the nut is loosely seated against the raised shoulder  60  of the body. 
   The body  152  of the connector includes a main body section  161  and a weakened end section  162 . The weakened body section is integrally joined to the main body section by a series of break away tabs  163 – 163 . The tabs are circumferentially spaced about the body so as to support the weakened end section in axial alignment with the main body section. Each tab has a root  165  that is joined to a ring shaped end wall  167  of the end section. The cross section of each tab preferably decreases uniformly as the tab extends toward the main body section so that the joint between the end section and the main body section, although strong enough to support the end section in axial alignment with the main body section, can be easily broken away from the main body section when an axial load is applied to the body section. 
   As best illustrated in  FIG. 8 , the inside diameter D 1  of the main body section is slightly greater than the diameter D 2  of the weakened end section. The tips of the tabs are also provided with a wedge configuration which combines with the reduced inside diameter to insure that the weakened end section will move into telescoping relationship with the main body section when a sufficient axial force is applied to the body to cause the tabs to separate from the main body section. 
     FIG. 9  shows the weakened end section removed from the main body section. In this embodiment, each tab tapers from its root  165  toward its terminal end  168  where the tab joins the main body section. The side walls  170  and  171  of each tab can also be tapered inwardly toward each other from the tab root toward the terminal end of the tab so that a relatively strong joint is established at the ring shaped end wall  167  while the joint that is formed at the tip end of each tab at the main body section is considerably weaker insuring that failure will occur at the tip of the tabs. 
   The connector is shown in  FIG. 10  assembled with an end portion of a conventional coaxial cable generally referenced  172 . The cable has a center conductor  73  that is surrounded by a dielectric material  174  which may or may not be covered by a conductive foil. A wire mesh shield  175  is placed over the dielectric layer which in turn is surrounded by a protective outer jacket  176 . Prior to insertion into the connector the cable is prepared by rolling back the outer jacket and the wire mesh shield to expose the dielectric layer. The end portion of the dielectric layer is cut away to expose a length of the center conductor. 
   In assembly the prepared end of the cable is inserted into the weakened end of the connector so that the post passes between the dielectric layer and the mesh shield of the cable. An axial force is then applied to the body to break away the weakened end section and telescope the end section inside the main body section. The telescoped portion of the weakened end section exerts a compressive force upon the cable to tightly engage the cable between the telescoped portion of the end section and the hollow post thus locking the cable to the connector. 
   In this embodiment of the invention, the threaded nut which is rotatably supported upon the flanged end of the post is an annular shaped member that is adapted to be hand tightened to a male connection. To facilitate hand tightening of the nut, the outer surface of the nut is provided with a textured surface having shallow contoured grooves  178  which enable a tight non-slip hand grip to be secured upon the nut. 
   While the present invention has been particularly shown and described with reference to the preferred mode as illustrated in the drawing, it will be understood by one skilled in the art that various changes in detail may be effected therein without departing from the spirit and scope of the invention as defined by the claims.