CUSHIONED GRIP TWIST-ON WIRE CONNECTOR

Abstract: A twist-on wire connector (10) has a shell (12) of relatively rigid plastic material with at least a portion of the shell exterior covered by a cushioned grip (14) of relatively softer material. The cushioned grip (14) has a higher coefficient of friction than the shell material to provide both a softer feel and an improved gripping ability.

Description: CUSHIONED GRIP TWIST-ON WIRE CONNECTOR 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'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's prefer not to bother with pulling out a tool to apply a connector. They just use their fingers because that'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'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. Patent 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. Patent 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. 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 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 is preferably made of a thermoplastic elastomer, 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. Patent 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 16 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'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 surface. The ledges 46, 48 and undercuts 50, 52 provide a positive stop at the boundaries of the grip mounting surface that prevents leakage of the grip material during molding. This assures the cured grip material will be located only on the grip mounting surface 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 grip mounting surface 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. 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. The cushioned grip could extend onto the skirt all the way to the open end. 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.

Claims: CLAIMS: 1. A twist-on wire connector, comprising: a shell made of relatively rigid material and having an exterior surface; and a cushioned grip made of material that is softer than said relatively rigid material, said cushioned grip covering at least a portion of the exterior surface. 2. The wire connector of claim 1 wherein the shell exterior surface further comprises a grip mounting portion underlying said cushioned grip, the grip mounting portion terminating at at least one boundary edge that is substantially normal to the grip mounting surface. 3. The wire connector of claim 2 wherein the grip mounting portion further comprises at least one wing which at least partially terminates laterally at first and second undercuts. 4. The wire connector of claim 1 wherein the shell has a generally frusto-conical shape defining a longitodinal axis, the exterior surface comprising a grip mounting portion underlying said cushioned grip and having at least one boundary defined by a ledge extending radially of said axis. 5. The wire connector of claim 4 wherein the shell exterior surface further comprises a closed end section on one side of the grip mounting portion and a skirt on the opposite side of the grip mounting portion, the boundaries between the grip mounting portion and the closed end section and skirt being defined by ledges extending radially of said axis. 6. The wire connector of claim 5 wherein the grip mounting portion further comprises at least one wing which is bounded by the skirt at first and second undercuts. 7. The wire connector of claim 4 wherein the grip mounting portion further comprises at least one wing which at least partially terminates laterally at first and second undercuts. 8. The wire connector of claim 1 wherein the cushioned grip has a plurality of grooves therein. 9. The wire connector of claim 1 wherein the shell has a generally frusto-conical shape defining a longitudinal axis and having a closed end and an open end, the cushioned grip extending longitudinally from the open end toward the closed end. 10. The wire connector of claim 9 wherein the exterior surface comprises a skirt adjacent the open end, a closed end section adjacent the closed end, and a grip mounting portion underlying said cushioned grip, the grip mounting portion extending from the open end to the closed end section. 11. A twist-on wire connector, comprising: a shell made of material having a first coefficient of friction and having an exterior surface; and a cushioned grip made of material having a second coefficient of friction that is higher than the first coefficient of friction, said cushioned grip covering at least a portion of the exterior surface. 12. The wire connector of claim 11 wherein the shell exterior surface further comprises a grip mounting portion underlying said cushioned grip, the grip mounting portion terminating at at least one boundary edge that is substantially normal to the grip mounting surface. 13. The wire connector of claim 12 wherein the grip mounting portion further comprises at least one wing which at least partially terminates laterally at first and second undercuts. 14. The wire connector of claim 11 wherein the shell has a generally frusto-conical shape defining a longitudinal axis, the exterior surface comprising a grip mounting portion underlying said cushioned grip and having at least one boundary defined by a ledge extending radially of said axis. 15. The wire connector of claim 14 wherein the shell exterior surface further comprises a closed end section on one side of the grip mounting portion and a skirt on the opposite side of the grip mounting portion, the boundaries between the grip mounting portion and the closed end section and skirt being defined by ledges extending radially of said axis. 16. The wire connector of claim 15 wherein the grip mounting portion further comprises at least one wing which is bounded by the skirt at first and second undercuts. 17. The wire connector of claim 14 wherein the grip mounting portion further comprises at least one wing which at least partially terminates laterally at first and second undercuts. 18. The wire connector of claim 11 wherein the cushioned grip has a plurality of grooves therein. 19. The wire connector of claim 11 wherein the shell has a generally frusto-conical shape defining a longitodinal axis and having a closed end and an open end, the cushioned grip extending longitudinally from the open end toward the closed end. 20. The wire connector of claim 19 wherein the exterior surface comprises a skirt adjacent the open end, a closed end section adjacent the closed end, and a grip mounting portion underlying said cushioned grip, the grip mounting portion extending from the open end to the closed end section.

Inventors: BLAHA WILLIAM E, BLAHA, WILLIAM, E.
Applicants: IDEAL IND, IDEAL INDUSTRIES, INC.
Application year: 2000
Main classification: H01R4
IPC codes: H01R4, H01R13