Abstract:
A locking mechanism inhibits rotational movement of a nut of a first cable connector that is threadingly engaged with a mating second cable connector. The nut has at least one recess in its outer surface along an edge and is rotatably mounted on a fixed housing of the first cable connector. The mechanism includes a component adapted to removably surround at least a portion of the housing and includes at least one first element matingly engageable with a corresponding second element positioned on the housing. A projection is rigidly mounted on the component. The projection is adapted to engage the at least one recess of the nut when the component is engaged with the outer surface of the housing.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to cable connectors for use in high vibration environment. 
     BACKGROUND OF THE INVENTION 
     Cables have been connected using known electrical connectors. Some of these connections involve threaded connections wherein the female connector has external threads and the male connector has corresponding internal threads. Radio Frequency (RF) connectors, which maintain the shielding, are used with coaxial cables while minimizing the change in the transmission line impedance at the connection. Some RF connectors mechanically fasten with one another only via threads, for example. In a high vibration environment, such connectors may back off, resulting in compromised connections. Means such as liquid sealants for maintaining connections are known in the art. However such means are not reliable and potentially hazardous. Applying such means also involve manual labor. Alternative mechanisms are desired. 
     SUMMARY OF THE INVENTION 
     An embodiment of the invention includes a locking mechanism to inhibit rotational movement of a nut of a first cable connector that is threadingly engaged with a mating second cable connector. The nut has at least one recess in its outer surface along an edge and is rotatably mounted on a fixed housing of the first cable connector. The mechanism includes a component adapted to removably surround at least a portion of the housing. The component includes at least one first element matingly engageable with a corresponding second element positioned on the housing. The mechanism further includes a projection rigidly mounted on the component. The projection is adapted to engage the at least one recess on the nut when the component is engaged with the outer surface of the housing. 
     Yet another embodiment of the invention includes a kit for providing a locking mechanism to inhibit rotational movement of a nut of a first cable connector that is threadingly engaged with a mating second cable connector. The nut has at least one recess on its outer surface and is rotatably mounted on a fixed housing of the first connector. The kit includes a tension strap having at least one first element. The tension strap is dimensioned to circumscribe the housing. The kit also includes a spring clip having at least one projection projecting longitudinally and at least one second element adapted to matingly engage with the at least one first element. The projection is adapted to matingly engage the at least one recess. 
     According to an aspect of the present invention, there is disclosed a method for inhibiting rotational movement of a nut of a first cable connector that is threadingly engaged with a mating second cable connector. The nut has at least one recess in its outer surface along an edge, and is rotatably mounted on a fixed housing of the first cable connector. The method includes a step of removably securing a component to at least a portion of the housing. The component includes at least one first element matingly engageable with at least one corresponding second element positioned on the housing. The method further includes a step of matingly engaging the component with the at least one recess on the nut via a projection rigidly mounted on the component, thereby securing the nut to the component and the housing. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Understanding of the present invention will be facilitated by consideration of the following detailed description of the exemplary embodiments of the present invention taken in conjunction with the accompanying drawings, in which like numerals refer to like parts and in which: 
         FIG. 1  illustrates a prior art connector assembly between two coaxial cables; 
         FIGS. 2A-2B  illustrate an exemplary tension clasp according to an embodiment of the invention; 
         FIGS. 3A-3C  show an exemplary spring clip according to an embodiment of the invention; 
         FIG. 4  illustrates an exemplary crown nut according to an embodiment of the invention; 
         FIGS. 5A-5B  show an exemplary method for restraining rotational movement of a crown nut, using the crown nut of  FIG. 4  and the spring clip of  FIGS. 3A-3B ; 
         FIGS. 6A-6C  illustrate another exemplary method for restraining rotational movement of a crown nut, using the tension strap of  FIGS. 2A-2B  and the spring clip of  FIGS. 3A-3B ; and 
         FIG. 7  illustrates an exemplary interface composed of a projection and a recess according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for purposes of clarity, many other elements found in typical electrical connectors. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements is not provided herein. The disclosure herein is directed to all such variations and modifications known to those skilled in the art. 
       FIG. 1  depicts a prior art electrical connector assembly  100  for coupling together coaxial cables  110 ,  120 . Connector assembly  100  includes a female connector  130  and a male connector  140 . Female connector  130  includes a first hollow body  132 , a housing  134 , and a connecting ring  135 . First hollow body  132  is adapted to receive cable  110 . Connecting ring  135  has external threads  136  formed on the outer surface of ring  135 . An end of cable  110  is inserted through hollow body  132  whereupon female connector  130  is affixed to cable  110 . Male connector  140  includes a second hollow body  143 , a nut  144 , a housing  145 , a crown nut  142 , and a connector structure  148  containing one or more electrical connections. Second hollow body  143  is adapted to receive cable  120 . Connector structure  148  is adapted to engage a socket assembly (not shown) positioned within female connector  130 . Connector structure  148  contains one or more electrical connections (not shown) therein, which connection(s) is adapted to be received in a corresponding socket (not shown) within female connector  130  so as to establish an electrical connection between two coaxial cables  110 ,  120 , as is well known by those of ordinary skill in the art. Crown nut  142  has internal threads (not shown) defined on the interior surface of nut  142 , adjacent to edge  141  facing connecting ring  135 . The internal threads (not shown) of crown nut  142  are adapted to engage exterior threads  136  when crown nut  142  is rotated in a given direction, thereby driving nut  142  onto connecting ring  135 , thereby establishing a mechanical connection between cable connectors  130 ,  140  to maintain the aforementioned electrical connection established between cables  110 ,  120 . An end of cable  120  is inserted through second hollow body  143  whereupon male connector  140  is affixed to cable  120 . Nut  144  is used to maintain a tight grip of second hollow body  143  over cable  120 . Crown nut  142  further includes a plurality of recesses  147  which assist in gripping nut  142  while tightening or loosening the connection between connectors  130 ,  140 . Recesses  147  are defined on the outer surface of crown nut  142 , along a circumferential edge  146  adjacent to housing  145 . Recesses  147  extend longitudinally, at least partially, along crown nut  142 . Male connector  140  also includes a housing  145  having an outer diameter smaller than the inner diameter of crown nut  142 . Housing  145  has a smooth outer surface. 
       FIG. 2A  shows a front view of an exemplary tension strap  200 , while  FIG. 2B  shows a corresponding side view. In an exemplary embodiment, strap  200  includes an elongated planar member  210  formed of two layers  212 ,  214 . In an exemplary embodiment, two projections or bosses  220 ,  230  extend from layer  214 . In other embodiments, strap  200  may include indents instead of projections or bosses  220 ,  230 . A hook  240  and buckle  250  are attached to opposite ends of elongated member  210  and adapted to connect to one another about housing  145 . The dimensions of strap  200  are dependent on the dimensions of housing  145  (of  FIG. 1 ). The length of elongated member  210  is slightly less than the circumference of housing  145  (of  FIG. 1 ), thus ensuring a tight fit upon housing  145 . Elongated member  210  may be fabricated from a light metal, such as aluminum, of sufficient rigidity to provide strength to mount and retain bosses  220 ,  230 , but also sufficiently flexible to bend open to accommodate connector assembly  100  and sufficiently resilient to return to its original shape and be formed to housing  145 . In an exemplary embodiment, layer  212  may be implemented as a rubber backing for gripping the smooth outer surface of housing  145 . 
     Strap  200  is adapted to be mounted on housing  145  (of  FIG. 1 ). Planar elongated planar member  210  circumscribes housing  145 . Hook  240  at a first end of member  210  is inserted into and engages buckle  250  at a second end of member  210 . The insertion of hook  240  into buckle  250  may require a slight stretch in planar member  210 . The cooperation of hook  240  and buckle  250  induces tensile forces in planar member  210  because the length of planar member  210  is slightly less than the circumference around the outer diameter of housing  145 . Such tensile forces in member  210  causes strap  200  to compress layer  212  of planar member  210  and to tightly grip housing  145  (of  FIG. 1 ) thereby inhibiting a relative motion between strap  200  and housing  145  (of  FIG. 1 ). Layer  212 , made of a rubber backing, in one configuration, frictionally engages the outer surface of housing  145  (of  FIG. 1 ) as an additional measure to inhibit relative motion between strap  200  and outer surface of housing  145  (of  FIG. 1 ). In an exemplary embodiment, rubber backing may be similar in thickness and texture to those of an inner tube for a bicycle tire. 
     Referring now to  FIGS. 3A and 3B , a component in the form of a spring clip  300  is illustrated. Component  300  is adapted to removably surround at least a portion of housing  145 .  FIG. 3A  illustrates a side-view of a spring clip  300  adapted to engage the RF connector assembly  100  for providing a more secure connection, whereas  FIG. 3B  illustrates a front view of spring clip  300 . In an exemplary configuration, as seen in  FIGS. 3A-3B , spring clip  300  includes a generally curved member  310 . Member  310  defines a generally circular shape. Member  310  has two ends  370 ,  380  defining an opening  390 . In an exemplary embodiment, member  310  has two indents  340 ,  350 . Indents  340 ,  350  may also be through apertures. Indents  340 ,  350  are adapted to accommodate projections or bosses  220 ,  230  (of  FIGS. 2A-2B ) respectively. The number of indents in member  310  may vary depending on the number of projections or bosses on strap  200  so long as there is a one-to-one correspondence between at least one of indents  340 ,  350  and at least one of projections or bosses  220 ,  230 . Preferably, there exists a one to one correspondence between all indents  340 ,  350  and bosses  220 ,  230 . In other embodiments, when strap includes indents, clip  300  may include projections or bosses instead of indents  340 ,  350 . One skilled in the art will appreciate the various combinations that are possible wherein strap  200  may have one projection and one indent, while clip  300  may have corresponding indent and projection. These and other such variations are contemplated to be within the scope of the present invention. Clip  300  has two pinch tabs  320 ,  330 . Tabs  320 ,  330  are located generally symmetrically about the mid-point of member  310 , in an exemplary embodiment. As illustrated in  FIG. 3C , pressing tabs  320 ,  330  towards each other causes ends  370 ,  380  to move away from each other thereby increasing the width of opening  390 . To mount clip  300  on housing  445  and/or strap  200 , tabs  320 ,  330  are pressed towards each other to increase the width of opening  390  sufficient to surround at least a portion of housing  445  and/or strap  200 . Clip  300  is then mounted on housing  445  and/or strap  200  by aligning indents  340 ,  350  with projections or bosses  220 ,  230 . Tabs  320 ,  330  are then released to secure clip  300  to housing  445  and/or strap  200 . Clip  300  may be unmounted by again pressing tabs  320 ,  330  to increase the width of opening  390  and removing clip  300  away from housing  445  and/or strap  200 . Thus, clip  300  is adapted to removably surround at least a portion of housing  445 . 
     Clip  300  further includes a projection  360 . Projection  360  projects generally longitudinally, and in an exemplary embodiment, orthogonally from member  310  in a direction parallel to the central axis  315  of member  310 . In an embodiment, projection  360  has a width generally equal to the width of recess  147  (of  FIGS. 1 ,  4 ) and is adapted to engage at least one of recesses  147  (of  FIG. 1 ) or recesses  447  (of crown nut  142  of  FIG. 4 ). In another embodiment, projection  360  may have two or more prongs, each adapted to engage one of recesses  147 . Projection  360  is sufficiently rigid so as to resist shear forces resulting from environmental vibrational or rotational forces below a given threshold level. When clip  300  is mounted on housing  445  and/or strap  200 , projection  360  is aligned to mate with a recess  147 . 
     Referring now to  FIG. 4 , another exemplary embodiment of a male connector  440  includes a crown nut  142 , and a housing  445 . In an exemplary embodiment, housing  445  has two projections or bosses  420 ,  430  on its outer surface. Projections  420 ,  430  extend radially from the outer surface, i.e., generally orthogonally from the outer surface, of housing  445 . In an exemplary embodiment, projections or bosses  420 ,  430  are generally cylindrical and have generally circular cross-section. In other embodiments, projections  420 ,  430  may have different cross-sections. Projections  420 ,  430  are adapted to be received by indents  340 ,  350  (of clip  300  of  FIGS. 3A-3B ). In an exemplary embodiment, the height and the width of projections  420 ,  430  are generally equal to the depth and the width of indents  340 ,  350  (of clip  300  of  FIGS. 3A-3B ) to establish mechanical coupling between housing  445  and clip  300 , sufficiently rigid to resist any relative rotational movement therebetween. In other embodiments, the height of projections  420 ,  430  is sufficiently big to restrain the relative motion of clip  300  (of  FIGS. 3A-3B ) with respect to housing  445 , once projections  420 ,  430  are lodged into indents  340 ,  350  (of clip  300  of  FIGS. 3A-3B ). Thus, the form and function of projections  420 ,  430  is similar to those of projections or bosses  220 ,  230  (of strap  200  of  FIGS. 2A-2B ). 
     Referring now to  FIG. 5A-5B , a method for inhibiting unintended rotation of nut  422  about female connector  130  (of  FIG. 1 ), for example, in a high vibration environment, will be described. The mechanism generally restrains the unintentional rotational motion of crown nut  422 , once male connector  440  has been threadingly coupled to female connector  130 . Male connector  440  is mechanically and electrically coupled to coaxial cable  120  (of  FIG. 1 ) and female connector  130  (of  FIG. 1 ) is mechanically and electrically coupled to coaxial cable  110  (of  FIG. 1 ), which are not further described for the sake of brevity. In an exemplary embodiment, male connector  440  is then mechanically coupled to female connector  130  (of  FIG. 1 ) by threadedly engaging nut  422  with external threads  136  of connecting ring  135  (of  FIG. 1 ), once an electrical connection between cables  110 ,  120  has been established. Such a threaded coupling between crown nut  422  and connecting ring  135  is generally sufficient to maintain mechanical and electrical connections between male connector  440  and female connector  130  in absence of external forces on the threaded coupling. However, when such a coupling is subjected to external forces such as vibrational forces, such vibrational forces may lead to a loosening of or even a gradual complete decoupling of the threaded connection between crown nut  422  and connecting ring  135 . This in turn may cause an undesired break in the electrical pin/socket connection between the two RF connectors  130 ,  440 . 
     To inhibit such a loosening of crown nut  422  from connecting ring  135 , a clip  300 , as shown in  FIGS. 3A ,  3 B, is mounted on housing  445  such that projections or bosses  420 ,  430  are received in indents  350 ,  340  respectively. Clip  300  acts as an intermediary between nut  422  and housing  445 , and effectively secures nut  422  to housing  445  as set forth below. The couplings of projections  420 ,  430  and indents  350 ,  340  operate as restraints on the relative motion of clip  300  with respect to housing  445 . A torque or a rotational force, below a given threshold level, exerted on clip  300 , in a clockwise or a counter-clockwise direction, will be resisted by the respective couplings of projections  420 ,  430  and indents  350 ,  340 , thereby inhibiting rotational motion of clip  300  about housing  445 . Clip  300  is thus effectively affixed to housing  445 . Projection  360  is further caused to mate with a recess  447  in crown nut  422 . Without clip  300 , the external vibrational or rotational forces may cause crown nut  422  to start to threadedly disengage from, or to loosen from, connecting ring  135  (of  FIG. 1 ). Such unintended rotational movement of nut  422  about connecting ring  135  results in a movement of nut  422  in a direction proximal to housing  445 , thereby compromising the integrity of the mechanical and ultimately the electrical couplings between connectors  130 ,  440 . However, when clip  300  is secured about housing  445 , if a rotational force causes nut  422  to loosen from external threads  136  (of  FIG. 1 ), (for example, in a high vibration environment), such rotational motion will be restrained by clip  300  as set forth below. Clip  300  is effectively affixed to housing  445  via projections or bosses  420 ,  430  lodged in indents  350 ,  340  respectively. Projection  360  lodged in recess  147  effectively affixes clip  360  to crown nut  422 . Thus, crown nut  422  is effectively restrained in its motion relative to housing  445 . External vibrational or rotational forces, below a given threshold level, acting on nut  422  are then resisted by projection  360  lodged in recess  147 . Projection  360  and bosses  420 ,  430 , thus, inhibit the rotational motion crown nut  422  relative to housing  445  as well as to connecting ring  135  (of  FIG. 1 ) and keep intact the mechanical and electrical coupling between female connector  130  (of  FIG. 1 ) and male connector  440 . 
       FIG. 6A-6C  illustrate another exemplary mechanism for inhibiting nut  422  from loosening from external threads  136  (of  FIG. 1 ). Tension strap  200  is positioned circumferentially about the outer surface of housing  145  of male connector  140  and buckled via hook  240  and buckle  250  so as to surround housing  145 . As previously discussed, strap  200  includes projections or bosses  220 ,  230 . Strap  200  is tightly wrapped about portion  445  to generally resist rotational motion about housing  445 . Clip  300  is mounted on strap  200  such that indents  340  receive projections or bosses  220 ,  230  and projection  360  mates with recess  447  and such that it surrounds at least a portion of housing  445 . The rotational motion of nut  422  relative to connecting ring  135  (of  FIG. 1 ) and to housing  145  is restrained as described above by projection  360  and recess  447  as well as projections or bosses  220 ,  230  and indents  340 . 
       FIG. 7  illustrates another exemplary configuration of projection  760  on a clip  700  and recesses  747 . Projection  760  has two prongs  762 ,  764 . Recesses  747  are similar in shape to teeth on a gear and are defined on an edge  746  proximal to clip  700 . Prongs  762 ,  764  engage with recesses  747  and restrain rotational motion of crown nut  742  relative to connecting ring  135  (of  FIG. 1 ) and to housing  745 . 
     Another embodiment of the invention includes a kit for restraining rotational motion of a crown nut  142  having at least one recess  147 . The kit includes a tension strap  200 , and a spring clip  300 . Strap  200  is dimensioned to circumscribe housing  145  of a male connector  140  such that there is no significant relative motion between the housing  145  and strap  200 . 
     It will be apparent to those skilled in the art that modifications and variations may be made in the system of the present invention without departing from the spirit or scope of the invention. It is intended that the present invention cover the modification and variations of this invention provided they come within the scope of the appended claims and their equivalents.