Abstract:
A twist-on wire connector has a shell of relatively rigid plastic material with at least a portion of the shell exterior covered by a cushioned grip of relatively softer material. The cushioned grip has a higher coefficient of friction than the shell material to provide both a softer feel and, an improved gripping ability.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of U.S. application Ser. No. 09/374,032, filed Aug. 13, 1999, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     Twist-on wire connectors are well-known devices for making connections between two or more electrical wires. The connectors typically have a hollow shell or cap of insulating material. The shell is also sometimes referred to as a housing or body. The interior surface of the shell is threaded to enable the shell to grip the conductors tightly and retain the connector on the ends of the wires. The threads are often formed by a coiled metal spring inserted into the shell. The outside edges of the spring are embedded in the inner walls of the shell to hold the spring in the shell and prevent it from pulling out. The interior edges of the coil spring are engageable with the stripped ends of the wires. 
     Installation of a twist-on connector involves stripping the insulation from the ends of the wires and inserting the exposed conductors into the shell. Then the user twists the shell to seat the conductors firmly in the threads. It is not ordinarily necessary to pre-twist the wires as the twisting action of installation will sufficiently compress the wires together to make a sound electrical connection. The twisting action is most commonly performed using just the installer&#39;s fingers, although many connectors are designed to be compatible with ordinary wrenches or specialized wrenches so extra torque can be applied if desired. However, it is possible to apply too much torque which causes failure of the shell such as by driving the wires through the closed end of the shell. Accordingly, most electrician&#39;s prefer not to bother with pulling out a tool to apply a connector. They just use their fingers because that&#39;s the quickest, most convenient way to get the job done. Furthermore, many connector designs employ extensions commonly known as wings which provide an enlarged gripping surface for the thumb and forefinger to enable application of sufficient torque. While applying connectors with the fingers is normally fully effective, prolonged, repeated installation in this manner can lead to discomfort and fatigue. When a job requires installation of numerous connectors, the hard, plastic surface of the shell can be a pain in the fingers. Also, the usual plastic shell surface can be slippery in instances where the user&#39;s fingers are sweaty or soiled. 
     Dual durometer twist-on connectors having a shell with a rigid upper body and a flexible lower skirt are taught in U.S. Pat. No. 5,132,494. This connector does not place the flexible material on top of the rigid material to form a cushioned grip and all the twisting forces would have to be placed on the rigid body portion. U.S. Pat. No. 5,151,239 discloses a twist-on connector formed within an outer shell or housing having gripping ridges but these ridges do not provide a cushioned grip. 
     SUMMARY OF THE INVENTION 
     The present invention provides a twist-on wire connector with an enhanced feel for improved gripping ability and cushioning. The connector has a shell of conventional interior construction but with an exterior surface having a cushioned grip. In one embodiment the exterior surface is modified from the conventional construction to facilitate forming the cushioned grip thereon. In a second embodiment the cushioned grip is formed on a standard exterior surface. The cushioned grip has a higher coefficient of friction and a lower hardness than typical shell materials, thereby making the connector both easier to grip and more comfortable on the fingers. The improved grip reduces the need for the user to squeeze the connector as hard. This reduces fatigue when numerous connectors have to be applied. The exterior surface of the shell may have a grip mounting portion with clearly defined edges or boundaries. These edges provide a positive stop to keep the grip material from leaking during molding. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the wire connector assembly of the present invention. 
     FIG. 2 is a bottom plan view of the connector assembly. 
     FIG. 3 is a perspective view of the wire connector shell prior to formation of the cushioned grip. 
     FIG. 4 is a bottom plan view of the shell of FIG.  3 . 
     FIG. 5 is a front elevation view of an alternate embodiment of a wire connector according to the present invention. 
     FIG. 6 is a side elevation view of the connector of FIG.  5 . 
     FIG. 7 is a plan view of the connector of FIG.  5 . 
     FIG. 8 is a section taken along line  8 — 8  of FIG.  5 . 
     FIG. 9 is an exploded perspective view of the FIG. 5 wire connector&#39;s shell and cushioned grip. 
     FIG. 10 is a front elevation view of a further alternate embodiment of a wire connector according to the present invention. 
     FIG. 11 is a side elevation view of the connector of FIG.  10 . 
     FIG. 12 is a plan view of the connector of FIG.  10 . 
     FIG. 13 is a section taken along line  13 — 13  of FIG.  10 . 
     FIG. 14 is an exploded perspective view of the FIG. 10 wire connector&#39;s shell and cushioned grip. 
     FIG. 15 is a front elevation view of yet another alternate embodiment of a wire connector according to the present invention. 
     FIG. 16 is a side elevation view of the connector of FIG.  15 . 
     FIG. 17 is a plan view of the connector of FIG.  15 . 
     FIG. 18 is a section taken along line  18 — 18  of FIG.  15 . 
     FIG. 19 is an exploded perspective view of the FIG. 15 wire connector&#39;s shell and cushioned grip. 
     FIG. 20 is a front elevation view of a further alternate embodiment of a wire connector according to the present invention. 
     FIG. 21 is a side elevation view of the connector of FIG.  20 . 
     FIG. 22 is a plan view of the connector of FIG.  20 . 
     FIG. 23 is a section taken along line  23 — 23  of FIG.  20 . 
     FIG. 24 is an exploded perspective view of the FIG. 20 wire connector&#39;s shell and cushioned grip. 
     FIG. 25 is a front elevation view of a still another alternate embodiment of a wire connector according to the present invention. 
     FIG. 26 is a side elevation view of the connector of FIG.  25 . 
     FIG. 27 is a plan view of the connector of FIG.  25 . 
     FIG. 28 is a section taken along line  28 — 28  of FIG.  25 . 
     FIG. 29 is an exploded perspective view of the FIG. 25 wire connector&#39;s shell and cushioned grip. 
     FIG. 30 is a perspective view of a further alternate embodiment of a wire connector according to the present invention. 
     FIG. 31 is a side elevation view of the connector of FIG.  30 . 
     FIG. 32 is a plan view of the connector of FIG.  30 . 
     FIG. 33 is a section taken along line  33 — 33  of FIG.  31 . 
     FIG. 34 is an exploded perspective view of the FIG. 30 wire connector&#39;s shell and cushioned grip. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1 and 2 illustrate the connector of the present invention generally at  10 . The connector includes a shell  12  and a cushioned grip  14 . The shell in this embodiment and the alternate forms shown below is preferably made of polypropylene although other relatively rigid, electrically insulating materials could be used, such as nylon, polycarbonate or similar thermoplastic materials. The cushioned grip in this embodiment and the alternate forms shown below is preferably made of an olefinic thermoplastic vulcanizate, such as SANTOPRENE®, a trademark of Advanced Elastomer Systems of Akron, Ohio. Rubber could also be used. Other possible materials are listed in the aforementioned U.S. Pat. No. 5,132,494, and their disclosure is incorporated by reference herein. 
     Details of the shell are shown in FIGS. 3 and 4. The shell has a generally frusto-conical wall  16  that defines a longitudinal axis. The wall also defines an open end  17  and an interior bore. The bore has an outer portion  18 , an inner portion  20  and a transition section  22  separating the inner and outer portions. The interior surface of the wall at the outer portion  18  has threads  24  formed therein. The inner portion  20  receives a coil spring (not shown) which is embedded or otherwise fixed to the interior surface of the wall  16 . An end wall  26  terminates the inner bore and defines a closed end of the shell. 
     The exterior surface of the shell has three main areas, a closed end section  28 , a skirt  30  and a grip mounting portion  32 . The closed end section may have a plurality of longitudinal ridges  34  alternating with pairs of grooves  36  as shown. The ridges are located to cooperate with a hex socket if desired. The skirt  30  preferably has a smooth outer surface. Its interior surface carries the threads  24  as explained above. 
     The grip mounting portion  32  in this embodiment has three parts, an annular band  38  and two longitudinal wings  40  and  42 . The wings divide the skirt into two pieces and extend onto the band area  38 . The wings  40 ,  42  protrude somewhat from the rest of the shell and provide a location where a user&#39;s fingers can easily grip and apply torque to the connector for affixing it to the wires. The wings have a series of grooves  44  formed therein. The band  38  terminates at first and second ledges  46  and  48 . Each ledge extends radially of the shell. Thus, the ledges are substantially normal to the adjoining surface of the grip mounting portion. First ledge  46  extends radially inwardly from the grip mounting portion surface, while second ledge  48  extends radially outwardly therefrom. The ledges provide a definitive edge or boundary for the grip mounting surface. Similarly, the wings  40  and  42  are bounded by first and second undercuts  50  and  52  formed adjacent the skirt sections. 
     The cushioned grip  14  is formed such that it overlies the grip mounting portion  32 . That is, the grip lies on top of the annular band  38  and the wings  40 ,  42 . The grip will take on the grooved pattern of the wings so the grip will also have a series of grooves in the area of the wings. The connector is made by a two-step molding process. First the shell is molded, then the cushioned grip is molded over and around the shell in the area of the grip mounting portion. The ledges  46 ,  48  and undercuts  50 ,  52  provide a positive stop at the boundaries of the grip mounting portion that prevents leakage of the grip material during molding. This assures the cured grip material will be located only on the grip mounting portion and not on the skirt  30  or closed end section  28  of the shell exterior surface. 
     The term substantially normal as used herein means the angle between the surface of the grip mounting portion and the boundary edge is great enough to allow the molds to fit tightly against the shell and prevent leakage of the cushioned grip material during molding. It has also been found that molds with particularly close tolerances can permit the cushioned grip to be formed over a conventional twist-on connector (such as the Twister® connector sold by IDEAL Industries, Inc.) without the use of boundary edges. With closely controlled tolerances a tight fit between the connector and the mold will prevent leakage of the grip material during molding. 
     FIGS. 5-9 illustrate an alternate embodiment of a wire connector according to the present invention. The connector  54  includes a shell  56  and a cushioned grip  58 . The exterior surface of the shell has first and second portions including a closed end section  60  and a grip mounting portion  62 . The exterior of the shell also has a small, exposed area below the grip mounting portion forming a ring  64 . The closed end section may have a plurality of longitudinal grooves  65  as shown. As in the previous embodiment the grip mounting portion  62  includes an annular band  66  which is divided by two longitudinal wings  68  and  70 . The band  66  terminates at upper and lower undercuts  72  and  74 . Each undercut extends generally radially of the shell. Thus, the undercuts are substantially normal to the adjoining surface of the grip mounting portion. In this case the upper and lower undercuts  72 ,  74  extend radially inwardly from the closed end section  60  and from the ring  64 , respectively. The undercuts provide a definitive edge or boundary for the grip mounting portion  62 . In this embodiment the undercuts  72 ,  74  extend throughout the entire perimeter of the grip mounting portion  62 . As a result the edges of the cushioned grip are everywhere flush with the exterior surface of the shell  56 . That is, the junctions of the cushioned grip  58  with the closed end section  60  and with the ring  64  present smooth surfaces, as best seen in FIG.  8 . 
     The cushioned grip  58  is formed such that it overlies the grip mounting portion  62  but does not overlie the closed end section  60  or the ring  64 . That is, the grip  58  lies on top of the annular band  66  and the wings  68 ,  70 . The grip has a series of grooves  76  in the area of the wings. The connector  54  is made by the same two-step molding process described above. First the shell is molded, then the cushioned grip is molded over and around the shell in the area of the grip mounting portion. The undercuts  72 ,  74  provide a positive stop at the boundaries of the grip mounting portion that prevents leakage of the grip material during molding. 
     FIGS. 10-14 illustrate a further alternate embodiment of a wire connector according to the present invention. The connector  78  includes a shell  80  and a cushioned grip  82 . The exterior surface of the shell has first and second portions including a closed end section  84  and a grip mounting portion  86 . The exterior of the shell also has a small, exposed area below the grip mounting portion forming a ring  88 . The closed end section may have a set of flat surfaces  89  forming a hexagonal closed end as shown. As in the previous embodiment the grip mounting portion  86  includes an annular band  90  which is divided by two longitudinal wings  92  and  94 . The band is also interrupted in this embodiment by a pair of islands  96 . The band  90  terminates at upper and lower undercuts  98  and  100 . Each undercut extends generally radially of the shell. Thus, the undercuts are substantially normal to the adjoining surface of the grip mounting portion. In this case the upper and lower undercuts  98 ,  100  extend radially inwardly from the closed end section  84  and from the ring  88 , respectively. The undercuts provide a definitive edge or boundary for the grip mounting portion  86 . The undercuts  98 ,  100  extend throughout the entire perimeter of the grip mounting portion  86 . As a result the edges of the cushioned grip are everywhere flush with the exterior surface of the shell  80 . 
     The cushioned grip  82  is formed such that it overlies the grip mounting portion  86  but does not overlie the closed end section  84  or the ring  88 . That is, the grip  82  lies on top of the annular band  90  and the wings  92 ,  94 . The grip has a series of grooves  102  in the area of the wings. There are apertures  104  in the grip which receive the islands  96 . The connector  78  is made by the same two-step molding process described above. The undercuts  98 ,  100  provide a positive stop at the boundaries of the grip mounting portion that prevents leakage of the grip material during molding. 
     It will be noted in the embodiments of FIGS. 5-9 and  10 - 14  the grip mounting portion is completely recessed into the outer surface of the shell. In other words, the entire perimeter of grip mounting portion is defined by an undercut. This arrangement makes it easier to control the molding of the cushioned grip. 
     FIGS. 15-19 show yet another alternate embodiment of a wire connector according to the present invention. The connector  106  includes a shell  108  and a cushioned grip  110 . The exterior surface of the shell has first and second portions including a closed end section  112  and a grip mounting portion  114 . The exterior of the shell also has a small, exposed area below the grip mounting portion forming a ring  116 . As in the previous embodiment the grip mounting portion  114  includes a band  118  which is divided by two longitudinal wings  120 ,  122  and two peninsulas  124 ,  126 . Both the wings and the peninsulas extend upwardly from the ring  116 . The bottom edge of the band  118  terminates at a lower undercut  128 . The undercut extends generally radially of the shell and substantially normal to the adjoining surface of the grip mounting portion  114 . 
     The cushioned grip  110  is formed such that it overlies the grip mounting portion  114  but does not overlie the closed end section  112  or the ring  116 . That is, the grip  110  lies on top of the band  118  and the wings  120 ,  122 . The grip has a series of grooves  130  in the area of the wings. There are apertures  132  in the grip which receive the penisulas  124 ,  126 . The connector  106  is made by the same two-step molding process described above. The undercut  128  provides a positive stop at the lower boundary of the grip mounting portion that prevents leakage of the grip material during molding. 
     FIGS. 20-24 depict a further alternate embodiment of a wire connector  134 . The connector  134  includes a shell  136  and a cushioned grip  138 . The exterior surface of the shell has first and second portions including a closed end section  140  and a grip mounting portion  142 . The closed end section may have a plurality of longitudinal grooves  144  as shown. The grip mounting portion  142  includes an annular band  146  which is divided by four longitudinal wings, three of which are shown at  148 ,  150  and  152 . The wings extend upwardly from the band  146  onto the closed end section  140 . The bottom edge of the band  146  terminates at the lower or open end of the shell  136 . The cushioned grip  138  is formed such that it overlies the grip mounting portion  142 . That is, the grip  138  lies on top of the band  146  and the wings  148 ,  150 ,  152  and the fourth wing that is not visible in FIG.  24 . The portion of the grip coverings the wings may have a rib  156  formed thereon. 
     FIGS. 25-29 illustrate still another alternate embodiment of a wire connector according to the present invention. The connector  158  includes a shell  160  and a cushioned grip  162 . The shape of the shell  160  is generally similar to that of shell  12  in FIGS. 1-4. The exterior surface of the shell  160  has first and second portions including a closed end section  164  and a grip mounting portion  166 . The grip mounting portion  166  includes an annular band  168  which is divided by two longitudinal wings  170  and  172 . The band  168  terminates at an upper ledge  174  which extends generally radially of the shell. Thus, the ledge is substantially normal to the adjoining surface of the grip mounting portion. The ledge provides a definitive edge or boundary for the grip mounting portion  166 . 
     The cushioned grip  162  is formed such that it overlies the grip mounting portion  166  but does not overlie the closed end section  164 . That is, the grip  162  lies on top of the annular band  168  and the wings  170  and  172 . In this form the grip also extends slightly beyond the open end of the shell to cushion the edges of the shell. This is best seen in FIG.  28 . The grip has a series of grooves  176  in the area of the wings. 
     An additional alternate embodiment of the invention is shown in FIGS. 30-34. This connector  178  has a shell  180  and a cushioned grip  182 . The exterior surface of the shell has first and second portions including a closed end section  184  and a grip mounting portion  186 . The exterior of the shell also has a small, exposed area below the grip mounting portion forming a ring  188 . The closed end section may have a plurality of longitudinal grooves  190  as shown. The grip mounting portion  186  includes a band  192  and two longitudinal wings  194 ,  196 . The bottom edge of the band  192  terminates at a lower ledge  198  which extends generally radially of the shell and substantially normal to the adjoining surface of the grip mounting portion  186 . However, unlike in several of the previous embodiments, the upper end of the band  192  is not defined by any particular feature of the shell. 
     The cushioned grip  182  is formed such that it overlies the grip mounting portion  186  but does not overlie the closed end section  184  or the ring  188 . That is, the grip  182  lies on top of the band  192  and the wings  194 ,  196 . The grip has a series of grooves  200  in the area of the wings. As best seen in FIG. 34, the grip  182  comprises two wing-covering pad areas  202  joined by a pair of straps  204 . Together the pads and straps encircle the shell  180 . This embodiment, as well as those of FIGS. 15-19 and FIGS. 25-29, has the advantage of requiring a less complicated mold. That is, the shells and complete connectors of these embodiments can be extracted axially from a mold cavity and therefore there is no need to split the mold axially. 
     While a preferred form of the invention has been shown and described, it will be realized that alterations and modifications may be made thereto without departing from the scope of the following claims. For example, while the grip mounting portion is shown having a continuous band around the middle of the shell, it could be otherwise. The cushioned grip might be formed of discrete, separate pads of elastomer rather than a continuous band. Also, it will be realized that the wings are not required. However, if wings are provided it is preferable to put the cushioned grip over them, since a user is almost certain to apply installation torque to the wings.