Abstract:
A coaxial cable connector includes a pin having a plurality of circumferentially spaced support arms, inward facing surfaces of the support arms defining a cavity. A shoulder is provided on the inward facing surfaces. A guide is axially received in the internal cavity, the guide having tabs at one and a radial flange at the other. An elastomeric cylindrical collar is disposed on the guide between the tabs and the flange. In a first position, the collar is axially uncompressed or axially partially compressed between the flange of the guide and the shoulders of the support arms. In a second position, the flange is positioned closer to the shoulders such that the collar is axially compressed between the flange and the shoulders to a shorter axial distance than in the first position and such that the collar is expanded radially outwardly to a greater amount than in the first position.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a continuation-in-part of U.S. application Ser. No. 11/608,610 filed on Dec. 8, 2006 and published on Jun. 12, 2008 as US 2008/0139047. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to the field of coaxial cable connectors and more particularly to a contact assembly within a connector for use with coaxial cables having a tubular center conductor. 
     BACKGROUND OF THE INVENTION 
     Some coaxial cables, typically referred to as hard line coaxial cables, include a center conductor that is constructed of a smooth-walled or corrugated, metallic (e.g., copper, aluminum, steel, copper clad aluminum, etc.) tube due to factors such as weight, cost, and flexibility. Such a center conductor is referred to herein as a tubular center conductor. 
     A tubular center conductor typically includes a hollow internal portion. Electrical connections to the tubular center conductor may be made within the hollow internal portion, because the electromagnetic signals within the coaxial cable pass using mainly the outer diametral portions of the tubular center conductor. Accordingly, coaxial cable connectors that are designed to work with such hard line coaxial cables typically include contacts that are extended within the hollow internal portion of the tube center conductor. Such coaxial cable connectors are referred to herein as hard line connectors. 
     The contacts used in many of these hard line connectors are held against the hollow internal portion by a support arm. Each of these contacts is located at or near an end of the support arm, which is cantilevered from a mounting position within the hard line connector. During installation, each of these support arms, along with its respective contact, is deflected to a smaller effective diameter during installation into the hollow internal portion. The amount of deflection may vary greatly. 
     Each support arm is designed to allow for an amount of elastic deflection before the support arm is plastically deformed. The amount of elastic deformation accounts for a variety of possible variations occurring between tubular center conductors. These variations may include manufacturing tolerances and design variations. These variations are typically small, but can be significantly large when the tubular center conductor is corrugated. It has been observed that many of such variations cause the support arms to deflect beyond their amount of elastic deflection and become plastically deformed during installation. Once the support arm is plastically deformed, it will not return to its original position after a deflection. 
     Any plastic deformation of the support arms may result in a poor electrical connection between the contacts and the hollow internal portion of the tubular center conductor. As described above, each contact may be held against the hollow internal portion by a respective support arm. An amount of pressure applied by each contact is determined by the amount of elastic deflection between a free-state position of each support arm and an installed-state position of the support arm. Accordingly, any amount of plastic deformation of the support arm during installation will result in a reduced free-state position and, therefore, a reduced pressure applied by each contact. 
     Previous attempts have been made to increase the amount of elastic deflection available to each support arm by reducing the cross sectional thickness of the support arm. This reduction in the cross sectional thickness naturally allows for greater elastic deflections before the support arm becomes plastically deformed. It is important to note, however, that this reduction in the cross sectional thickness correspondingly reduces the amount of pressure is applied to the contact. Any reduction in, or elimination of the amount of pressure applied to the contact may reduce the quality of the connection and degrade the signal. 
     Other attempts have been made to increase the amount of pressure applied to the contact by various methods, such as increasing the cross sectional thickness of each support arm and using more resilient materials. This increase in the amount of pressure comes with a strong disadvantage of increasing an amount of moving force required to install the contact assembly into the hollow internal portion of the tubular center conductor. This increased installation force may result in damaged contacts and/or an incomplete installation. Both of these outcomes may reduce the quality of the connection and degrade the signal. 
     SUMMARY OF THE INVENTION 
     The present invention helps to increase the quality of the connections made between the coaxial cable and the connectors. The present invention ensures that the contacts of the connectors are held against the tubular center conductor with an amount of pressure. The present invention provides for such pressure without requiring additional or increased installation forces. 
     In accordance with one embodiment of the present invention, a coaxial cable connector is provided that includes a pin having first and second ends. The pin has a plurality of circumferentially spaced support arms terminating at the second end. Inward facing surfaces of the support arms define an internal cavity. A shoulder is provided on the inward facing surface of each of the support arms, and the shoulder is placed a distance from the second end. The connector further includes a guide that is axially received in the internal cavity. The guide has at a first end a plurality of tabs, which fit into respective slots formed between the support arms. The guide has a second end opposite the first end, and the second end has a generally radially extending flange. The connector further includes a cylindrical collar that is disposed concentrically on the guide and extends between the tabs and the flange. The collar is composed of an elastomeric material, and at least a portion of the collar is positioned within the internal cavity. In a first position, the cylindrical collar is one of axially uncompressed and axially partially compressed between the flange of the guide and the shoulders of the support arms. In a second position, the flange is positioned closer to the shoulders such that the collar is axially compressed between the flange and the shoulders to a shorter axial distance than in the first position in a manner that can change how the collar is one of axially uncompressed and axially partially compressed relative to the first position, and such that the collar is expanded radially outwardly to a greater amount than in the first position. 
     In accordance with one embodiment of the present invention, the collar is composed of a rubber material. Preferably, the collar is composed of silicone rubber. 
     In accordance with one embodiment of the present invention, the tabs are disposed at an end of the slots in the second position. 
     In accordance with one embodiment of the present invention, the pin and guide are components within a cable connector, which connects to a coaxial cable having a tubular center conductor. In the first position, the pin and the guide are moveable into and out of the tubular center conductor by a relatively low moving force, and in the second position, the support arms and contacts formed thereon are pressed radially outwardly to a greater degree than in the first position. A pressure of the contacts against the tubular center conductor creates a moving force that is greater than the relatively low moving force. 
     In accordance with one embodiment of the present invention, the cable connector further includes an insulator. The tabs of the guide make contact with the insulator to radially center the pin and the guide within the cable connector. 
     In accordance with one embodiment of the present invention, a method is provided for attaching a connector to a coaxial cable having a tubular center conductor. The method includes providing a pin having first and second ends. The pin has a plurality of circumferentially spaced support arms terminating at the second end. Inward facing surfaces of the support arms define an internal cavity. A shoulder is provided on the inward facing surface of each of the support arms, and the shoulder is placed a distance from the second end. The method further includes providing a guide that is axially received in the internal cavity. The guide has at a first end a plurality of tabs, which fit into respective slots formed between the support arms. The guide has a second end opposite the first end, and the second end has a generally radially extending flange. The method further includes mounting a cylindrical collar concentrically on the guide so as to extend between the tabs and the flange, the collar being composed of an elastomeric material. The method further includes inserting the pin and the collar into the internal cavity with the plurality of tabs fitting into the respective slots. The method further includes moving the guide further into the cavity. The collar is axially compressed between the flange of the guide and the shoulders of the support arms to thereby cause the collar to expand radially outwardly. 
     In accordance with one embodiment of the present invention, the method includes mounting a cylindrical collar that is composed of a rubber material. Preferably, the collar is composed of silicone rubber. 
     In accordance with one embodiment of the present invention, the method includes providing a guide that has tabs that are disposed at an extreme end of the slots when the collar is in a compressed condition. 
     In accordance with one embodiment of the present invention, the method further includes providing an insulator and having the tabs engage the insulator to hold both the pin and the guide radially centered within the cable connector. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a further understanding of the nature and objects of the invention, references should be made to the following detailed description of a preferred mode of practicing the invention, read in connection with the accompanying drawings in which: 
         FIG. 1  shows a perspective exploded view of the parts of a hard line connector according to an embodiment of the invention; 
         FIG. 2  shows a partial cutaway perspective view of a hard line connector according to an embodiment of the invention which is in a first position of clearance within a tubular center conductor of a hard line coaxial cable; 
         FIG. 3  shows a partial cutaway perspective view of the hard line connector of  FIG. 2  that is in a second position of interference within the tubular center conductor of a hard line coaxial cable; 
         FIG. 4  shows a perspective view of a contact assembly according to an embodiment of the present invention in a first position of clearance; 
         FIG. 5  shows a perspective view of the contact assembly of  FIG. 4  in a second position of interference; 
         FIG. 6  shows a perspective exploded view of a contact assembly according to an alternative embodiment of the present invention; 
         FIG. 7  shows a perspective view of the contact assembly of  FIG. 6  in a first position of clearance; 
         FIG. 8  shows a perspective view of the contact assembly of  FIG. 6  in a second position of interference; and 
         FIG. 9  shows a partial cutaway perspective view of the contact assembly of  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , a hard line connector  10  according to an embodiment of the invention is shown in exploded form. The connector  10  includes a fastener  18  axially assembled onto a forward end  24  of an outer body  19 . The fastener  18  is held on the outer body  19  using a snap ring  17 , such that the fastener  18  can rotate in relation to the outer body  19 . 
     A mesh body  20  and an elastomeric clamp  21  are inserted into a rearward end  26  of the outer body  19 . A compression sleeve  22  is then placed in the rearward end  26  of the outer body  19 . 
     A contact assembly  11  is positioned between a first insulator  13  and a second insulator  16 . The contact assembly  11 , the first insulator  13 , the second insulator  16 , and a sliding retainer  12  are inserted into the forward end  24  of the outer body  19 . In the embodiment shown, the sliding retainer  12  is preferably constructed from a conductive material such as metal, and the sliding retainer  12  is installed into the outer body  19  with an interference fit between the sliding retainer and the outer body  19 . If there is adequate electrical contact between the outer body  19  and the fastener  18 , the sliding retainer  12  may not need to be electrically conductive. 
     The term interference fit is used herein to describe a method of assembly that provides a retention force between the sliding retainer  12  and the outer body  19 . This retention force may be created as a result of a dimensional interference between the sliding retainer  12  and the outer body  19 . The retention force may also be created by other known methods, such as methods that include an adhesive, interlocking mechanical components, and other devices and implements that can create the retention force. 
     Referring now to  FIG. 2 , a coaxial cable  28 , which includes a tubular center conductor  30 , is attached to the connector  10  as follows. The mesh body  20 , the elastomeric clamp  21 , and the compression sleeve  22  are removed from the outer body  19 . A portion of an outer conductor  62  of the coaxial cable  28  is exposed for contact with the mesh body  20 . The cable  28  is then inserted through the compression sleeve  22 , the elastomeric clamp  21 , and the mesh body  20  with the mesh body  20  positioned close to the end of the cable  28 . A portion of the cable  28  is then positioned within the outer body  19  and the compression sleeve  22  is forced into the outer body  19 , squeezing the elastomeric clamp  21  and the mesh body  20  into the outer conductor  62  of the cable  28 . The cable  28  is held in place within the connector  10  as a result of an axial compression of the compression sleeve  22 . 
     Referring now to  FIGS. 2 and 3 , the contact assembly  11  is moved from a first position of clearance ( FIG. 2 ) into a second position of interference ( FIG. 3 ) when the sliding retainer  12  is pushed toward the cable  28 . The movement of the sliding retainer  12  repositions the first insulator  13  in relation to the second insulator  16 . Accordingly, a ridge  44  of the contact assembly  11  is pushed toward tabs  32  of the contact assembly  11 . The relative movement between the ridge  44  and the tabs  32  of the contact assembly  11  will be discussed in greater detail below in relation to a first embodiment ( FIGS. 4 and 5 ) and a second embodiment ( FIGS. 6-9 ) of the contact assembly  11 . The ridge  44 , the tabs  32  and the contacts  60  (discussed below) in each of the first embodiment and the second embodiment use the same reference numbers to avoid confusion. The relative functions of the ridge  44 , the tabs  32 , and the contacts  60  are similar between the two embodiments. 
     The first embodiment of the contact assembly  11  is shown in  FIGS. 4 and 5 .  FIG. 4  shows the contact assembly  11  in the first position of clearance ( FIG. 2 ), and  FIG. 5  shows the contact assembly  11  in the second position of interference ( FIG. 3 ). The second embodiment of the contact assembly  11  is shown in  FIGS. 6-9 .  FIG. 7  shows the contact assembly  11  in the first position of clearance ( FIG. 2 ), and  FIGS. 8 and 9  show the contact assembly  11  in the second position of interference ( FIG. 3 ). 
     Referring to  FIG. 4 , a pin  14  includes a plurality of slots  38 , which create a plurality of finger-like support arms  40 . A guide  15  includes a plurality of corresponding tabs  32  that fit within the slots  38 . The tabs  32  are sized to extend beyond the slots  38  a distance sufficient to engage a mating surface  61  ( FIGS. 2 and 3 ) on the second insulator  16 . Each support arm  40  includes a ramped portion  34  on an underside of an end  42 . The ramped portion  34  on the support arm  40  interacts with a ramped portion  36  at or near an end of the guide  15  opposite the tabs  32 . A contact  60  is located on an outer surface of each support arm  40 , the outer surface being the surface intended to directly face the tubular center conductor  30  within the hollow internal portion of the coaxial cable  28 . 
     In the first position of clearance shown in  FIG. 4 , the contact assembly  11  will slide into and out of the tubular center conductor  30  of the cable  28  ( FIG. 2 ) with a relatively low moving force. The relatively low moving force will occur when the contacts  60  are pressed, even lightly, against the tubular center conductor  30  during assembly. It should be noted, that this relatively low moving force includes the possibility of a very low or no moving force being required to insert the contact assembly  11  when the contacts  60  on the pin  14  do not touch the tubular center conductor  30 . For example, with this relatively low moving force, the contact assembly  11  can be slid into the hollow internal portion of the tubular center conductor  30  with less force than would be required when the connector assembly  11  is in the second position of interference. 
     In the second position of interference shown in  FIG. 5 , the ends  42  of support arms  40  and the contacts  60  are being supported by the ramped portions  34  of the support arms  40  interacting with the ramped portion  36  of the guide  15 . This additional support provides additional contact pressure between the contacts  60  and the tubular center conductor  30 . This additional contact pressure increases the moving force required to displace the connector assembly  11  within the tubular center conductor  30 , the increased moving force being greater than the relatively low moving force described above in relation to the first position of clearance. 
     It is envisaged that the ends  42  of the individual support arms  40  will be moved outward by the transition of the guide  15  from the first position of clearance to the second position of interference. It should be noted, however, that such movement of the support arms  40  and the contacts  60  is not required. For example, when the pin  14  is not inserted within the hollow inner portion of the tubular center conductor  30 , the ends  42  of the support arms  40  may remain in the same or nearly the same position such that an effective diameter circumscribing the contacts  60  remains the same or nearly the same. In the second position of interference, the ends  42  of the support arms  40  may be supported more closely by the guide  15  such that the pressure required to deflect the contacts  60  to an inner diameter of the tubular center conductor  30  is greater than when the guide  15  is in the first position of clearance. It is this difference in contact pressure that changes the moving force required to displace the connector assembly within the tubular center conductor  30 . 
     Referring now to  FIG. 6 , the second embodiment of the contact assembly  11  is shown in exploded form. The second embodiment of the contact assembly  11  includes a pin  46 , a guide  50 , and a cylindrical collar  57 . Similar to pin  14  described above, the pin  46  includes a ridge  44 . Further, the pin  46  has a plurality of circumferentially spaced slots  49  at one end defining a plurality of finger-like support arms  47  with ends  48 . A contact  60  is positioned on an outer surface of each support arm  47 . Each of the support arms  47  includes a substantially radially extending shoulder  51 , which is disposed between a larger internal diameter portion  52  and a smaller internal diameter portion  53 . The function of these elements will be described more fully below. 
     The guide  50  is similar to the guide  15  described above in that it includes a plurality of circumferential spaced tabs  32 , which fit into and extend through the slots  49  of the pin  46  to engage a mating surface  61  ( FIGS. 2 and 3 ) of the second insulator  16 . The tabs  32  are disposed on one end of a shaft portion  54 , and a radially extending flange  56  is disposed on the other end thereof. 
     The cylindrical collar  57  is concentrically disposed over the shaft portion  54 , between the tabs  55  and the flange  56 . The cylindrical collar  57  has coaxial ends  58  and  59  and is composed of a material that has a relatively low Young&#39;s modulus of between 1 and 25 MPa, like natural rubber, nitrile rubber, silicone rubber, styrene butadiene rubber, ethylene propylene diene rubber, urethane rubber, etc. Elastomers having a relatively low Young&#39;s modulus can be elastically compressed in an axial direction to create a radial deflection of the elastomer with a relatively low compressive force. Such elastomers should also have relatively low compressibility properties such that the material maintains a relatively consistent volume during an elastic deflection. This characteristic allow for an efficient transfer of an axial deflection into a radial deflection. It has been found that silicone rubber is a suitable material for the collar  57 . 
     The term “relatively” is used above in an effort to define the desired properties of the collar  57  while allowing design modifications that are envisaged to be within the scope of the present invention. In other words, it is envisaged that the collar  57  could be manufactured of a more rigid and/or more compressible material. In the case of a more rigid material, the collar  57  could be made having a thinner cross section and/or the installation tools could be made to provide a greater amount of installation force. Similarly, it is envisaged that a more compressible material could be used for the collar  57  when less actual radial deflection is desired while using the same amount of axial deflection. 
     Referring now to  FIG. 7 , the contact assembly  11  is shown in the first position of clearance. The collar  57 , which is mounted on the shaft portion  54 , can be axially inserted into the larger inner diameter portion  52  of the support arm  47 . The inner end  58  of the collar  57  abuts the shoulder  51 , and the outer end  59  of the collar  57  is engaged by the flange  56  of the guide  50 . The tabs  32  are not at the end of the slots  49  but are spaced therefrom. In this first position of clearance, the collar  57  is exerting relatively little, if any, force against the support arms  47 . Similar to the first embodiment discussed above, the contacts  60  of the second embodiment of the contact assembly  11  can be inserted into the hollow internal portion of a tubular center conductor  30  using the relatively low moving force when the contact assembly  11  is in the first position of clearance. 
     In the second position of interference shown in  FIGS. 8 and 9 , the guide  50  is moved in relation to the pin  46  so that the contacts  60  can apply a greater pressure against the hollow internal portion of the tubular inner conductor  30 . As discussed above in relation to the first embodiment, the additional contact pressure will increase the moving force required to displace the contact assembly  11  within the tubular center conductor  30 . 
     Similar to the first embodiment, the relative axial movement between the ridge  44  and the tabs  32  is initiated by an axial movement of the sliding retainer  12 . The tabs  32  hold the position of the guide  50  stationary in relation to the second insulator  16 , and the pin  46  is advanced over the guide  50  because of the axial movement of the sliding retainer  12  and the first insulator  13 . As the pin  46  and its support arms  47  are moved further toward the guide  50 , the shoulder  51  causes the collar  57  to be axially compressed. In the process, the collar  57  expands radially outwardly to press against the support arms  47 . At the same time, the tabs  32  come to rest at the end of the slots  49 . 
     Similar to the first embodiment discussed above, it is envisaged that ends  48  of the individual support arms  47  will be moved outward by the transition of the guide  50  from the first position of clearance to the second position of interference. It should be noted, however, that such movement of the support arms  47  and the contacts  60  is not required. For example, when the pin  46  is not inserted within the hollow inner portion of the tubular center conductor  30 , the ends  48  of the support arms  47  may remain in the same or nearly the same position such that an effective diameter circumscribing the contacts  60  remains the same or nearly the same. In the second position of interference ( FIGS. 8 and 9 ), the ends  48  of the support arms  47  may be supported more closely by the guide  50  and the collar  57  such that the pressure required to deflect the contacts  60  to an inner diameter of the tubular center conductor  30  is greater than when the guide  50  is in the first position of clearance (shown in  FIG. 7 ). It is this difference in contact pressure that changes the moving force required to displace the connector assembly within the tubular center conductor  30 . 
     As will be understood, because of the flexibility of the collar  57 , there exists a range of possible motion of the support arms  47  in the radial direction. In this way, the same connector can be used with coaxial cables having internal diameters that vary due to manufacturing tolerance and/or corrugations. 
     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.