Abstract:
A cord grip in which two screw fittings provide a variable volume chamber for compressing a flexible soft durometer grommet held within a flexible annular cord gripping member. The cord gripping member is of a harder durometer than the grommet and has a plurality of fingers for gripping the cord. The combination of the hard durometer cord gripping member and the soft durometer grommet provides positive gripping action and a liquid tight seal on the cord when the variable volume chamber within the fittings is in the compressed state.

Description:
FILED OF THE INVENTION 
     This invention relates to cord grips and in particular to a four piece liquid tight grip including two interconnecting threaded fittings of hard plastic or metal, a cord gripping member of flexible medium hardness plastic-like material, and a cord sealing member of a flexible elastomeric material. 
     BACKGROUND OF THE INVENTION 
     Water tight cord grips are a well known type of cord fitting. Some of the present designs include grommets that provide water tightness when squeezed by internal tapers when the fitting is tightened to grip a cable. Heretofore, cord grips that were liquid tight were of many different designs in a crowded art but still there is room for improvement in one or more areas including simplicity, ease of use, ease of manufacture, improved performance in accommodating a size of cords and so forth. 
     SUMMARY OF THE INVENTION 
     This invention provides a cord grip that consists of four interacting parts that provide positive cord gripping action and a liquid tight sealing action between the cord and the grip. The invention is very economical to mass produce as each of the four separate parts may easily be manufactured by a simple casting procedure. 
     OBJECTS AND ADVANTAGES 
     An object of the invention is to provide a simple and practical cord grip the parts of which may be cast and economically mass produced. 
     Another object is to provide a cord grip that is easy for the customer to apply and use. 
     Another object is to provide a cord grip that can handle a wide range of cord diameters. 
     Another object is to provide a cord grip that provides a positive locking action on the cord preventing an undesired retraction of the cord from the grip. 
     Another object of the invention is to provide a liquid tight seal between the cord and the cord grip. 
     Other objects and advantages of the present invention will be better understood from the following description when read in conjunction with the appropriate drawings. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a frontal view of the cord grip of the present invention with a cutaway section showing at the bottom the variable volume chamber in an uncompressed state and at the top in the compressed state. 
     FIG. 2 is a view of the first fitting with the right side cutaway to show the interior. 
     FIG. 3 is a view of the cord gripping member with the right side cutaway. 
     FIG. 4 is a view of the grommet having the right side cutaway. 
     FIG. 5 is a view of the second fitting with the right side cutaway. 
    
    
     DESCRIPTION OF THE INVENTION 
     A first fitting or sleeve 14 depicted in FIG. 2 may be molded from rigid plastic-like material or metal. A passageway 20 extends through the sleeve 14 and includes an inclined or tapered conical surface 18. The inclined surface 18 extends around the inner periphery of the sleeve and resembles an inner surface of a truncated cone. The sleeve 14 has a necked down area 24 adjoining the top edge or smallest diameter of the inclined surface 18. The sleeve 14 has external threads 16 at one end to facilitate connection with a second fitting and external threads 60 at its opposite end to facilitate connection to a box, panel, etc. through a standard hole either by the use of a threaded hole or a lock nut together with a watertight washer (not shown). A section intermediate the two ends of sleeve 14 has a raised polygonal surface 22 to facilitate tightening with a wrench or similar tool. 
     An annular cord gripping member 36 depicted in FIG. 3 may be molded of any flexible plastic of medium hardness and has a passageway 44 therethrough and a plurality of fingers 38 integral with its base 39. Fingers 38 contain tabs 42 that extend from the end of the fingers toward a central axis of the cord gripping member 36. The fingers contain tips 40 and an abutment edge or shoulder 62 as part of each tab 42. The tab is thicker than the rest of the finger by the width of the shoulder 62. The shoulders 62 all lie in the same plane that extends transverse to the central axis of the cord grip assembly. The cord gripping member 36 has a base edge or face 41 at the lower end of the circular base 39. 
     FIG. 4 depicts an annular sealing member or grommet 46 which is typically molded of a flexible and soft elastomeric material. The hardness or durometer of the grommet is of a lower value than that of the cord gripping member 36 depicted in FIG. 3 which is in turn of a lower hardness or softer durometer than the sleeve 14. The grommet 46 has an external sealing surface 50 on its outer circumference, a rear sealing face 64 at its lower end and an inner sealing surface 48 on its inner circumference. A passageway 52 extends through the grommet 46. The grommet has a forward edge or face 54 shown at the top of FIG. 4. The grommet is the same thickness in its relaxed or non-compressed state as the depth of the shoulder 62 of cord gripping member 36. Likewise, the relaxed length and diameter is approximately equal to the distance from shoulder 62 to base face 41 and the inner diameter of cable passageway 34 through the cap 26, respectively. It is to be noted that fingers 38 taper to rounded out tips 40 and that they are separated by slots 66 that taper from a point adjacent circular base 39 to diverge to their greatest width at the tips 40. This permits the fingers to cantilever inward a great distance until the sides of the tips 40 touch one another. 
     A second fitting or cap 26 is shown in FIG. 5. The cap 26 is not continuous but has a passageway 34 therethrough. The cap has internal threads 30 and a flat compression surface 28. A polygonal surface 32 is provided on the exterior surface of the cap 26 to permit tightening with a wrench or similar tool. 
     FIG. 1 shows a cutaway view of the sleeve 14, cap 26, cord gripping member 36, and grommet 46 and how they interact to form the present invention. The grommet 46 is typically pressed into the cord gripping member 36 where it bottoms on shoulders 62. The tabs 42 on the fingers 38 of the cord gripping member form a cage which acts to hold the grommet within the cord gripping member. The grommet 46 slides into the cord gripping member 36 until the shoulders 62 at the base of the tabs 42 holds the grommet 46 from further entry. At this point, base face 41 of the cord gripping member 36 and the rear sealing face 64 of the grommet 46 lie in the same plane. The sleeve 14, cord gripping member 36 with the grommet 46 inserted therein, and the cap 26 are then slid onto a cord. The cap 26 is then loosely threaded onto the mating end of the sleeve 14 so that internal threads 30 of the cap 26 are engaging external threads 16 of the sleeve 14. Alternately, the sleeve 14, cord gripping member 36 with the grommet 46 inserted therein, and the cap 26 may be assembled loosely together first and then the cord inserted therein, the net result being the same. 
     The assembled sleeve 14, cap 26, grommet 46, and cord gripping member 36 are shown in FIG. 1 with the cord 12. The bottom half of FIG. 1 shows the separate pieces comprising the cord grip 10 in the uncompressed state and the top half of FIG. 1 shows the same components in the compressed state. In the uncompressed state the cord gripping member 36 abuts the interior flat surface 28 of the cap 26 at its base face 41. The grommet 46 also abuts the flat surface 28 of the cap 26 at the sealing face 64 of the grommet. The tips 40 of fingers 38 contact the inclined surface 18 of the sleeve 14. The forward face 54 of grommet 46 is held by the shoulders 62 of the tabs 42 on fingers 38. 
     Further tightening of the sleeve 14 into the cap 26 causes the interior flat surface 28 to push both the base face 41 of the cord gripping member and the face 64 of the grommet into the sleeve 14. This causes fingers 38 of the cord gripping member 36 to slide down the inclined surface 18 and be pivoted or forced inwardly toward the central axis of the cord 12. The tightening action also causes a compression inwardly of the grommet 46 so that the external sealing surface 50 of the grommet 46 seals against the inner surface 43 of the cord gripping member 36. It is to be noted that the compression and movement of the grommet 46 is inward and not longitudinal since it is held from longitudinal movement by shoulders 62 and flat surface 28. The inner surface 48 of the grommet 46 also seals against the surface of the cord 12. In addition, compression of the grommet 46 causes it to seal at its rear sealing face 64 to the flat compression surface 28 of the cap 26. The tightening action is continued until the tabs 42 of fingers 38 create a firm but non-invasive bite 68 into the cord 12 as seen in FIG. 1 at the upper half. The cord 12 is then locked in place in the cord grip 10. The cord gripping member 56 and the grommet 58 in their compressed states are shown in the top half of FIG. 1. The cord is in a liquid tight fit as a result of compression of the grommet 46, which is of a softer durometer than the cord gripping member 36. 
     The sleeve 14 and the cap 26 are both rigid hard members of plastic or metal and the cord gripping member 36 is a resilient softer member of moderately firm plastic. The grommet is a soft rubber-like or elastomeric member that is readily deformable. The preferred material and their source for these different components are: 
     a) sleeve 14 and cap 26: type of material: nylon material #600AZIP22 available from: Texapol Corporation Lower Nazareth Commercial Park 177 Mikron Road Bethlehem, Pa. 18107 
     b) grommet 46: type of material: sanoprene material #20187 available from: Advanced Elastomer Systems 7715 South 78th Avenue Bridgeview, Ill. 60455 
     c) cord gripping member 36: type of material: poly propylene material #59139 available from: Marsh Plastic 4043 Maple Road Amherst, N.Y. 14226 
     While the grip is shown with two interfitting parts, the sleeve 14 and cap 26, threaded together to define a variable bottom compression chamber with the sleeve 14 having an inclined surface and the cap 26 having a flat pushing or compression surface 28, such may be reversed so the inclined surface is on the cap and the flat surface is on the sleeve. 
     Having thus described the invention with reference to a preferred embodiment, it is to be understood that the invention is not so limited by the description herein but is defined as follows by the appended claims.