Abstract:
A cord lock with an internal structure designed to guide a pair of cord parts through the device smoothly to minimize friction thereby increasing final tension in the cord parts. And further designed to guide the cord exit on the operators side to facilitate a tightening method where the cord parts can be held one in each hand and pulled apart giving the operator more leverage and multiplying the tension force in the cord parts ( 13 ).

Description:
SUMMARY 
       [0001]    This device is used to selectively lock a pair of cords using a wedge between the two cords arranged within housing. The housing is specifically designed to minimize the friction of the cords by accepting them from substantially opposite directions and smoothly direct them out again in substantially opposite directions. 
       BACKGROUND 
       [0002]    1. Prior Art 
         [0003]    There are a number of prior art designs similar to my cord lock. None, however, are fashioned in a way that minimizes the friction due to abrupt curves in the cord due to their design. The inner walls, which guide the cord in the prior inventions that cause these abrupt curves, are designed without regard for this effect. Furthermore, the accepted method of tightening is to hold the device with one hand and pull both cords through the device with the other hand. Evidence of this is shown in the illustrations in many of the prior art where the loose end of the cord is shown extending in a direction generally parallel to each other and parallel the axis of the device. The intended operation of this device involves tightening the cord by holding one cord in each hand and pulling outward on each separately. This provides a much greater mechanical advantage. Each of the prior art do not anticipate this method of tightening the cords. If this were anticipated by the prior art it would have been mentioned and illustrated. Another detail not anticipated by the prior art is that the wedge shaped locking member passes through the narrowest point of the cavity in the outer body of each device. Furthermore, the wedge effect of the previous devices is dependant in full or part on the shape of the inner cavity. The shape of the cavity in this device is shaped primarily to minimize deviation from a smooth path into and out of the device. 
         [0004]    Boden 4,156,574, May 29, 1979, shows a locking device where, in  FIG. 2  and  FIG. 3 , The inner surfaces that the cord is forced against while locked, is concave. This displaces the inevitable turn in the cord to a point immediately near each exit of the cavity of the device. Specifically, at both points  17 , in  FIG. 2 , very tight turns cause the cord to curve in a very abrupt manor and then proceed outward in opposite directions. The cord will tend to resist this deflection, creating high friction, which works against the manual force from the operator. Furthermore, at the opening opposite each point  17  at  16  in  FIG. 2  and  FIG. 3 , where the cord exits on the other end of the cavity, the shape is almost square. In the case where the operator holds one cord in each hand separately and pulls them apart, the square shape causes a friction effect that is additional to the friction force created at points  17 . Each of these friction effects, together and separately result in less tension in the cord in its&#39; final locked position and less effectiveness of the device. 
         [0005]    Bengtsson, 3,564,670, Feb. 23, 1971, teaches a cord lock device with the same disadvantage created by the same type of concave shaped wall at  29  in  FIG. 14 . This displaces the inevitable turn in the cord creating conditions for an abrupt-friction-causing turn at  12  in  FIG. 9  and  FIG. 10  as well as  30  in  FIG. 14 . 
       OBJECT AND ADVANTAGES 
       [0006]    The object of my cord lock is to provide a cord lock that is easier to tighten and provide a greater tension in cords where this arrangement is needed. A further object is to deliberately facilitate a method of tightening the cord where the operator holds one cord in each hand and pulls them apart. The advantage to my cord lock is that the cord, passing through the cavity in the housing, is directed gradually from it&#39;s entry direction, through the cavity and then back out again without encountering abrupt deviations, bumps or dips as in the previous inventions. The smooth gradual redirection of the cord reduces the friction created as the cord is drawn through. The advantage of holding each cord in each hand is it provides a greater mechanical advantage practically quadrupling the force generated rather than holding the two cords in one hand. This doubles the manual force imparted to the cord providing a much greater final tension than can be generated in previous inventions. Furthermore, the wedge means can be drawn into the cavity a much greater distance with no limit established by the outer body. This allows and unlimited wedge force as needed. 
     
    
     
       DRAWING FIGURES 
         [0007]      FIG. 1  illustrates the cord lock fully assembled from the side.  FIG. 2  shows the cord lock as it would appear as viewed in  FIG. 1  from above.  FIG. 3  is a cross sectional view of the cord lock at view line  3  of  FIG. 2  in the unlocked position.  FIG. 4  is the same as  FIG. 3  with the cord lock in cross section in the unlocked position.  FIG. 5  shows the cross section of the housing  11  only.  FIG. 6  is the same as  FIG. 2  showing housing  11  only.  FIG. 7  shows the face view of wedge  12  alone.  FIG. 8  shows the edge view of wedge  12  alone. 
       
    
    
     DESCRIPTION 
       [0008]    The embodiment illustrated in all the figures are fabricated in the same manner as anyone skilled in the art will have made other cord locks and can employ standard injection molding to fabricate any of the parts from polymers or use of other die forming or molding methods. 
         [0009]    The cord lock  10  is illustrated in FIG I fully assembled showing a housing  11  holding a sliding wedge  12  and a pair of cord parts  13  in operating relation.  FIG. 2  shows a view as cord lock  10  would appear as viewed in  FIG. 1  from above.  FIG. 3  illustrates a cross section view of device in the unlocked position revealing the inner relationship of housing  11  where wedge  12  resides between cord parts  13 , which follow a pair of opposing convex walls  16 , which appear more clearly in  FIG. 5 .  FIG. 5  illustrates a cross section view of housing  11  free of cord parts  13  and wedge  12 .  FIG. 6  illustrates housing  11  from a view showing cavity  15  free of cord parts  13  and wedge  12  and further revealing a remaining pair of flat walls  19  that, with convex walls  16 , form cavity  15 .  FIG. 7  shows wedge  12  fashioned with a pair of sloped sides  17  at an angle  18  developed to optimize the locking characteristics of the device. Specifically, if angle  18  is too great it will act less as a wedge and not be drawn into cavity  15  properly, allowing cord parts  13  to slip past wedge  12 . If angle  18  is too small it will require too much travel to eventually lock as the wedge effect will be too gradual. There will be a range of angles where proper actuation will occur between the above mentioned extremes. There can also be a set of ridges  25 , shown in  FIG. 7  and  FIG. 8 , which can enhance the friction characteristics of wedge  12 .  FIG. 7  also shows a projection  21 , which resides in a slot  22  which resides in one wall  19 , seen in  FIG. 1  and has the purpose of restraining wedge  12  from movement beyond what is required for proper actuation of the device. Slot  22  has a length where wedge  12  is allowed to move from a position where the device is locked, to a position where cord parts  13  can move, as arrows  15  in  FIG. 3  indicate, yet still maintain slight contact so as not to loose communication with cord parts  13 . Housing  11  has walls  19  shown in  FIG. 6  that are designed to be flexible enough to allow wedge  12  to be installed and allow cavity  15  to be forced wider to allow projection  21  to pass under slotted wall  19  to engage slot  22 . Projection  21  has a length which allows desirable engagement in slot  22  without requiring wall  19  to be deformed upon installation of wedge  12  to a point where wall  19  will be damaged. Wedge  12  is further fashioned with a loop  24  shown in  FIG. 7 , which has a size and shape where it can be comfortably pulled, disengaging wedge  12  from a locked position. Holding wedge  12  by use of loop  24  in this fashion, cord parts  13  are allowed to move through the cord lock, without the device locking, to adjust cord parts  13  as needed before tightening. Wedge  12  has a loop  24 , which enables manual manipulation of wedge  12 . 
         [0010]    The cord parts  13  can be of one loop where a tension force is maintained and utilized in examples including but not limited to binding an object or bundle or to draw closed a bag or tighten a cover. The cord parts  13  can also be fastened to other objects to be drawn toward each other or held together in some fashion. 
       Operation 
       [0011]    To tighten cord parts  13 , cord parts  13  are pulled tight by the operator, in an outward direction, one cord part  13  in each hand, indicated by arrows  15  in  FIG. 3 . This draws a tension force in cord parts  13  on the opposite side of the cord lock. This also drags, by friction, wedge  12  outward until projection  21  reaches the end of slot  22 . In this position, wedge  12  still contacts cord parts  13  but not enough to prevent cord parts  13  from slipping past wedge  12 , but enough that, when the movement direction of cord parts  13  reverses, wedge  12  is dragged back into cavity  15 . When the operator releases cord parts  13 , the residual tension force in cord parts  13  on the opposite side of the cord lock, indicated by arrows  24  in  FIG. 4 , pulls cord parts  13  back through the device in a direction that drags the wedge  12  back into cavity  15 . Cord parts  13  are then wedged in a progressive manner against adjacent walls  16  of cavity  15 , causing the build up of friction resisting the residual tension force  24  in cord parts  13 . When the friction force builds to the point where it equals the residual tension force, cord parts  13  stop and are considered locked. This position is shown in  FIG. 4 . When cord parts  13  are once again pulled in the reverse direction, wedge  12  is dragged out of cavity  15  and the outward force it exerts against cord parts  13  holding them against the walls  16  of cavity  15  decreases releasing cord parts  13  to slide once again. Cord parts  13  can also be released by withdrawing wedge  12  from cavity  15 . In this embodiment this is accomplished by pulling loop  24  shown in  FIG. 7  so that cord parts  13  can be released when desired. 
       CONCLUSION AND RAMIFICATIONS 
       [0012]    The reader will see that my cord lock is an advancement in the technology and use of cords as fastening devices. With this advancement of drawstring arrangements, their use would be widened. Also the performance standard expected of these arrangements would be increased. 
         [0013]    While my above description contains many specificities, these should not be construed as limitations on the scope of the invention, but rather as an exemplification of one preferred embodiment thereof. Many other variations are possible. 
         [0014]    Accordingly, the scope of the invention should be determined not by the embodiment(s) illustrated, but by the appended claims and their legal equivalents.