Abstract:
A self-locking threaded connection including an externally threaded male part having a series of projections adjacent the trailing or last-to-be-threaded threads and an internally threaded female part having a series of detents adjacent the leading or first-to-be-threaded threads. As the parts are threaded together, the snap reception of the projections into the detents produce both audio and tactile responses indicating that the connection is made and near to a destructive over tightening.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a Continuation-in-Part of U.S. Ser. No. 10/891,399 filed Jul. 14, 2004. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT NONE REFERENCE TO A “SEQUENCE LISTING” 
       [0002]     Not applicable.  
       BACKGROUND OF THE INVENTION  
       [0003]     1. Field of the Invention  
         [0004]     This invention relates generally to a threaded connector, and more particularly but not by way of limitation, to a threaded connector that is self-locking as may be used either alone, or in combination with plumbing fixtures including but not limited to plumbing pipes and in particular to plumbing pipes subject to vibration such as garbage disposal drains and the like.  
         [0005]     2. Description of Related Art  
         [0006]     Manufacturers have long used various sorts of connections to assure a tight connection that can be undone if necessary, especially in the plumbing industry. Often two pipes are joined together permanently using piping dope or other forms of permanent adhesive that effectively form a plastic “weld”. These sorts of connections are quick and easy to make and do not require the exact tolerances that may be required for threaded connections. A disadvantage of this type of connection is that it is permanently welded in order to prevent fluid leaks. Thus, when there is a need to repair the plumbing, the connecting pipes must be cut.  
         [0007]     Alternatively if the plumbing connection is a threaded connection, gaskets, doping materials or other nonpermanent fluid sealing agents may be employed to assist the threads in making a fluid tight joint. A threaded connection is easily undone to make a repair or to replace one or more plumbing components or fixtures. Threaded connections often use a top lip to hold one pipe against another pipe often with the help of a gasket. However, even when there are in no internal pressures, as in a drain line, it may be difficult to make a threaded connection that effects a fluid tight seal and maintains a fluid tight seal over time.  
         [0008]     This is particularly the case if the plumbing is subjected to vibration, such as the drain from a sink drain, garbage disposal or dishwasher. In such cases the threaded connection may become loosened over time allowing leakage. Hence, plumbing connections in such situations are often over tightened in the attempt to make a tight seal. As it is not uncommon for drains such as sink drains and the like to be formed of plastic (such as PVC), over tightening may result in fractured or broken parts. Over tightened joints are also not easily disassembled or undone when needed. The following invention overcomes these problems by providing a threaded connector that is self-locking when the proper seal connection is made. The self-locking feature makes it very difficult to over tighten a plumbing connection that needs to be fastened to a specific tightness and allows ease of disassembly to undo the connection.  
       BRIEF SUMMARY OF THE INVENTION  
       [0009]     The present invention includes components of a threaded connection, including a male part having external threads and a female part with internal threads. The male part has one or more protrusions located such that when the female and male parts are mated together in a proper sealing relationship, the protrusions on the male part mate with and releaseably lock into recesses on the female part to resist loosening of the threaded joint. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)  
       [0010]      FIG. 1  is a front elevation view partly broken away and in section showing components of the self lock threaded coupling of the present invention prior to assembly;  
         [0011]      FIG. 2  is a side elevation view of the coupling partly broken away and in section showing the coupling as assembled;  
         [0012]      FIG. 3  is an end view of the female part of the coupling;  
         [0013]      FIG. 4  is a view taken generally along lines  4 - 4  of  FIG. 2 ;  
         [0014]      FIG. 5  is an elevation view, partly broken away and in section showing another embodiment of the invention;  
         [0015]      FIG. 6  is a sectional view taken generally along lines  6 - 6  of  FIG. 5 ; and  
         [0016]      FIG. 7  is a cross sectional view of the male member showing another embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]     Referring to the drawings,  FIG. 1  shows the coupling of the present invention generally indicated at  10 . The coupling includes a male part  12  comprising a pipe section  14  having exterior threads  16  at one end and a female part  18  having internal threads  20 . The female part  18  is threaded to the external threads  16  on the male part male part so as to couple an unthreaded pipe section  22  to the pipe section  14 .  
         [0018]     In this respect the unthreaded pipe section has a flat flange  24  that is engaged by a collar  26  on the female part and pressed against an end face  28  of the male part upon threading the male and female parts together (see  FIG. 2 ). Such a connection is common in plumbing fixtures such as in sink drains and the like.  
         [0019]     Plumbing connections of the type described are not usually employed in situations where there is an internal pressure. Accordingly, making the connection finger tight usually is sufficient to prevent leakage through the joint. In some cases a gasket (not shown) is inserted between the flange  24  and the end face  26 .  
         [0020]     The male part  12  has an entry thread portion  30  on a leading end and a trailing or last-to-be-engaged thread portion  32 . Adjacent the trailing thread portion  32  on the male part are a series of projections  34 , preferably three in number. The projections preferably are generally spherical and can either be fixedly imbedded into the wall structure of the male part or formed integral the wall structure. In either case the first two projections  34 A and  34 B are just in advance of, or lead, the trailing thread portion  32  in the direction of rotation (Arrow A) while at least one projection  34 C just trails or lags the trailing thread portion  32 .  
         [0021]     The female part  18  has an entry lip  36  and the leading thread portion  38  of the female part starts slightly inboard of the lip. The trailing or last-to-be connected female thread portion is identified at  40 . As best seen in  FIG. 3  the lip has a constant outside diameter. However the lip has a section indicated at  41  that is thicker than the remaining portion of the lip. This thicker section  41  is formed by a decrease in the inside diameter of the lip. Formed in this thicker section  41  is a series of spaced detents  42 , preferably four in number. These detents include detents such as  42 A and  42 B that are in advance of the leading thread portion  38  in the direction of rotation (Arrow B in  FIG. 1 ) while others such as detents  42 C and  42 D are alongside or over lap the leading thread.  
         [0022]     Accordingly, it should be appreciated that when a threaded connection is made, the detents  42  in the lip  36  of the threaded female part  18  pass over the entry thread portion  38  on the leading end of the male part. The threading continues unimpeded until the entry thread portion  30  of the female part approaches the trailing or last-to-be-engaged thread portion  32  of the male part. As the entry thread  38  of the female part nears the male trailing thread  32 , the first projection  34 A begins to encounter the thicker section  41  of the lip.  
         [0023]     As finger tightening continues, the first projection  34 A starts to bind against the inside surface of the lip at the thicker section (because of the decrease in the inside diameter) and then snaps into the first detent  42 A. The snapping of the projection into a detent produces an audio response as well as a tactile sensation that the user can “feel”, both indicating that the coupling is close to being made.  
         [0024]     As tightening continues still further, the first projection  34 A is forced out of the first detent  42 A and over into the second detent  42 B while the second projection  34 B first encounters the thickened setion  41  of the lip and then enters the first detent  42 A. With two projections bearing against the inside surface of the lip, the force required to tighten the coupling increases. This increase in the force needed to tighten the coupling as well as the tactile response each time a projection enters a detent cooperate to let the user know that the point is being reached where there is a danger of over tightening the coupling.  
         [0025]     Tightening the coupling still further forces the two projections  34 A,  34 B from their respective detents  42 B,  42 A and brings all three of the projections to bear against the inner surface of the lip  36 . These increases still further the force required to finger tighten the male and female parts together. Eventually all three of the projections  34  will be captured in detents  42 .  
         [0026]     While in the embodiment as described the number of projections exceeds the number of detents, it should be appreciated that the number of projections and detents can be equal. Also, the positions of the projections and detents can be reversed. In this respect  FIGS. 5 and 6  show projections  50  extending inward from the inner periphery of the lip  36  in advance of the leading threads  38 . In this embodiment the male part  12  has a thickened section  52  on its periphery adjacent the trailing or last-to-engage thread  32 . Formed in this thickened section are detents  54 . As the lip  36  passes over the trailing threads  32  on the male part the projections  50  on the lip engage first one and then another of the detents  54 .  
         [0027]      FIG. 7  shows another embodiment of the invention showing how the projections, rather than being formed integral the male part, may be embedded into the wall of the male part. In this respect  FIG. 7  shows that holes  60  are drilled through the wall  62  of the male part. Spherical elements  64  such as ball bearings or the like are placed into the holes, the diameter of the spheres being smaller than the diameter of the holes so the spherical elements don&#39;t fall through the holes. Then an adhesive such as an epoxy or the like is applied as shown at  66  to hold the spheres in place. In this embodiment the material of the spherical elements  64  preferably is harder that the material of the male and female parts. With this arrangement there is less wear of the projections when a coupling is made and this in turn allows for more repeated connecting and disconnecting of the coupling before the there is so much wear of the detents that the snap fitting loses its effectiveness.  
         [0028]     Accordingly, as the pipe collar  24  and the end face  28  of the male part are brought together to make a junction as shown in  FIG. 2 , the force required to thread the male and female parts together is at a maximum. As noted above the capture of the projections can be both felt and heard as a “snap” so both tactile and audio signals alert the user that the male and female parts are close to being fully tightened and that further tightening may result in an over tightening of the parts to the point of damaging the threads on either the male or female parts. These tactile and audio signals provide cautionary signals in addition to the increase in the resistive force that is felt during the finger tightening. Also, since one or more of the projections  34  are captured in one or more of the detents  42 , there is less of a likelihood of the coupling being separated by vibration.