This invention relates generally to wire connectors and, more specifically, to an epidermal friendly twist-on wire connector that inhibits or prevents epidermal trauma to the users fingers and thumb.
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The concept of twist-on wire connector with a cushioned grip is known in the art, more specifically Blaha U.S. Pat. No. 6,677,530 discloses numerous embodiments of twist-on wire connectors and points out that the cushioned grip is on a portion of the exterior hard or rigid shell with the cushioned grip being an olefinic thermoplastic vulcanizate sold under the name Santoprene®, a trademark of Advanced Elastomer system of Akron, Ohio. Blaha describes a twist-on wire connector wherein the exterior of the wire connector shell has three main areas, a closed end section, a skirt and a grip mounting portion. The grip mounting portion is the region the user engages with his or her fingers in order to twist the wire connector into engagement with an electrical wire or wires.
Blaha points out that with molds of particularly close tolerances, such as found in the Twister® wire connector a cushioned grip can be formed over the Twister® wire connector without the use of boundary edges. The twist-on wire connector with a cushioned grip on the grip mounting portion is sold by Ideal Industries Inc. under the name Twister®PRO and is shown in the web page downloaded from the Ideal Industries which is included with the 1449 material information statement of the present application.
Blaha points out the problem of installing twist-on wire connectors with a hard shell is that if numerous connections are made the hard plastic surface can be painful on the fingers or in certain instances the shell surface can be slippery due to the sweat or soil on the users hand. As a solution to the problem Blaha proposes to place a cushioned material over the hand gripping portions of the wire connector to make the wire connector more comfortable to grasp. While Blaha recognizes that the placement of cushion on the grip mounting portion of the twist-on wire connector can reduce fatigue Blaha does not recognize that not everyone grasps the twist-on wire connectors in the same manner or that because of cramped conditions it might not be possible to grasp the twist-on wire connector on the grip mounting portions to enable the user to benefit from the cushioned grip of Blaha. Consequently, while the Blaha twist-on wire connector has a cushioned grip it can be of little benefit to those users who do not grip the twist-on wire connector on the normal designated gripping portions or those users who might have to apply a twist-on wire connector in a location with inadequate space to position the users hand or fingers around the normal hand gripping regions of the twist-on wire connector. While Blaha U.S. Pat. No. 6,677,530 shows multiple embodiments of his cushioned grip in each of his embodiments he places his cushioned grip at the base or open end of his wire connector while leaving the end section of his wire connector proximate the closed end of the wire connector with the hard shell exposed. Ironically, if the twist-on wire connector is to be applied in a tight location it is the uncushioned end section which the user grasps to twist the wire connector onto the wires. Since the end section usually has a smaller radius than the base or normal finger grasping portion an increased hand or finger pressure is required to obtain necessary torque to apply the twist-on wire connector. Thus, when application conditions are the most difficult one not only does one not have the benefit of cushioned grip for the users fingers but one has to generate greater hand force on the twist-on wire connector to obtain the necessary torque to bring the wire connector into engagement with the electrical wires therein.
Krup U.S. Pat. No. 3,519,707 illustrates another type of twist-on wire connector wherein a vinyl shield with ribs is placed around an exteriors surface of rigid cage that has sufficient strength and rigidity to drive the spring onto a cluster of wires. Krup states the purpose of his vinyl shell around the rigid case is to insulate and protect the connector and the wire connector. However, Krup fails to teach that the vinyl shell located around his rigid cage comprises a cushioned surface that can reduce epidermal trauma.
McNerney U.S. Pat. No. 6,478,606 shows a twist-on wire connector with a tensionally-biased cover. McNerney fits a sleeve of heat shrinkable material over a portion of his wire connector so that after a wire connection is made the heat shrinkable material can be shrunk fit around his connector to improve the bond to his connector and around the wires in order to prevent contaminants from entering the wire splice in his wire connector. In order to have ridges for gripping McNernery points out a tube of heat shrinkable material tightly grips his hard shell so as to replicate the grooves in the hard shell of his connector. Unfortunately, tightly shrinking the material around the body of connector can introduce a circumferential bias or tension force in the heat shrunk material thus rendering material which may even be soft into a covering that is hard to the touch and is reluctant to yield to finger torque. Thus the heat shrunken tube on the body of his wire connector produces an external surface that resists resilient displacement and is also hard and is uncomfortable in response to the finger and hand pressure of the user since the tension and bias forces introduced by the heat shrinking limit the yielding of his material. That is, by stretching the material around the connector McNerney biases the material much like a spring under tension has an inherent bias. The bias introduced by the heat shrink process can prevent heat shrunk material from yielding equally in all three axis. Consequently, the heat shrinkable material in effect becomes like a stretched spring, which has increased resistance to stretching. The effect is to form an elastomer material into a hard cover or non resilient cover on a hard shell since a heat shrunk cover is limited in its ability to absorb external finger pressure. In addition any protuberances on the hard shell are carried through and become hard protuberances on the heat-shrunk layer. McNerney espouses the hardness of his heat-shrunk cover by pointing out that heat shrinking can produce a rigid case for his coil spring. In contrast to McNerney the present invention provides a cover to a twist-on wire connector that eliminates the problems generated by McNerney heat shrunk cover.
While other prior art reveals that pads, wings and ribs have been placed on the exterior of twist-on wire connectors to provide a good grip the art and that soft covers have been placed on portions of the twist-on wire connectors to cushion the grip the issue the art fails to recognize that epidermal trauma can occur even with soft covers during finger application of twist-on wire connectors because to secure the twist-on wire connector the user generates finger and thumb pressures that are in excess of those pressure that produce epidermal trauma.
A twist-on wire connector having a resilient cover that includes a resilient gripping region having a set of low profile, resilient ribs that are circumferentially spaced so that a users thumb and fingers can compressively engage and compress at least a portion of a plurality of ribs as well as the valley between the ribs with the finger and thumb pressure wherein the finger and thumb pressure on the twist-on wire connector generates a wire securement torque that is below a level that causes epidermal trauma to the users finger and thumb.
While it is known that pads, wings and rigid ribs have been placed on the exterior surface of twist-on wire connectors to provide a good grip the art is silent on epidermal trauma to the users fingers and thumb which is caused during applications of twist-on wire connectors. An aspect of the invention described herein is that the surface features of the twist-on wire connector not only enhance a users grip thereon but the surface features of the twist-on wire connector can also inhibit or prevent epidermal trauma on those portion of the users fingers and thumb that frictionally engage the twist-on wire connector by limiting the amount of finger and thumb pressure necessary to generate a wire securement torque on the twist-on wire connector. Epidermal trauma is a condition where the epidermis layer on the users finger and thumbs becomes irritated or ruptured by application of a wire securement torque to harsh external features on the twist-on wire connector and may appear as a wound or a discoloration of the skin or both.
While the placement of a partial cushion cover on the exterior surfaces of a twist-on wire connector has been used to cushion the users grip; however, little attention has been paid to the relationship between the epidermis layer of the thumb and fingers and the features on the circumferential surface of the twist-on wire connector, particularly, during applications of twist-on wire connector. As described herein it has been found that if certain features in a resilient cover are maintained on twist-on wire connectors of a family of different size finger friendly twist-on wire connectors one is able to both comfortably grasp and secure various size twist-on wire connector and generate a wire securement torque while also inhibiting or preventing epidermal trauma to the users thumb and fingers during applications of the twist-on wire connectors.
Typically, the epidermal contact area on a users finger that radially and frictionally engages an outer surface of the twist-on wire connector is on the order of about 0.2 square inches. Similarly the epidermal contact area on a users finger that radially and frictionally engages the outer surface of the twist-on wire connector is also on the order of about 0.2 square inches. While the size of the contact areas may vary depending on the size of the users fingers and thumb as well as the size of the twist-on wire connector it is these relatively small epidermal regions on the users finger and thumb that must transfer the necessary radial and tangential forces to create a wire securement torque. Briefly a wire securement torque is a torque that is sufficient to bring the twist-on wire connector into electrical engagement with a set of electrical wires. The wire securement torque may vary with the size of the wire connector or with the size and number of the electrical wires being secured but with each twist-on wire connector and set of wires there exists a minimal wire securement torque to bring the electrical wires into electrical engagement with each other. Oftentimes the application of the wire securement torque to prior art twist-on wire connectors causes epidermal trauma on the users thumb or fingers or both since the finger pressure required to generate the wire securement torque creates high pressure points on the epidermal layer which may rupture or tear the epidermal layer as the wire securement torque is applied to the connector. It is particularly true if the exterior surface of the twist-on wire connector contains rigid protuberances. In other cases even non-rigid protuberances may cause epidermal trauma because of the relationship between the protuberances and the supporting surfaces. For example, in some cases the spacing or the radial height variation between adjoining surfaces on the twist-on wire connector may result in epidermal trauma on the users fingers and thumb during the application of the wire securement torque to the twist-on wire connector.
In the example shown the ribs 12 and 13 are molded as part of a one-piece resilient cover 11 that extends over the rigid shell 31 which is centrally located in the interior of the twist-on wire connector. The resilient material 11, which may be an electrically insulating polymer plastic, that compresses in response to radial finger pressure and has sufficient tear resistance to resist separating from the connector as tangential forces are applied to the twist-on wire connector.
The combined radial support provided by the radially deformable ribs 12 and 13 and the valley 17 inhibits or prevents epidermal trauma to the users thumb and fingers since epidermal contact with the connector extends over an area defined by a circumferential arc of engagement, which is designated as S, in
As shown in
The yieldable feature of thinner materials is illustrated in
A further benefit of interspersing of a first group of resilient ribs between a second group of resilient ribs in a uniform relationship is that it enables the twist-on connector to be rolled between a users finger and thumb to retain the same touch and feel while maintaining the same rotational torque on the twist-on wire connector since the circumferential gripping surface is free of protrusions that may cause epidermal trauma. As can be seen in the Figures the resilient ribs 12 and 13 while tapering from a base toward the closed end of the twist-on wire connector generally have a uniform radial profile with rounded edges that provides a comfortable grip or feel to the twist-on wire connector.
To illustrate the relationship of the epidermal layer on the users thumb and fingers to the external features of the connector 100 reference should be made to
Similarly, if thumb 110 were to engage the twist-on wire connector 10 a similar set of imprints would occur over an arc distance S. A common feature of the imprints is that although the number of ribs on the twist-on wire connector are different the contact region on the users finger or thumb as well as the rib imprints remains substantially the same. By having at least three ribs and the valley in contact with the users finger or thumb one can reduce trauma to the epidermal layer of the users fingers and thumb since the wire securement torque is distributed over three ribs and the valley therebetween. In addition the use of resilient ribs rather than rigid ribs further reduces the epidermal trauma as the ribs can compress in response to the user grasping force thereby lessening trauma to the epidermal layers of the thumb and fingers. By inclusion of resilient valleys between the ribs and limiting the height of the ribs such that radial finger and thumb compression of the ribs brings the epidermal layer of the users skin into pressure engagement with both the valleys and the ribs also creates a comfortable feel and grip to the twist-on wire connector that allows a user to combat finger fatigue resulting from applying wire securement torque. The compressive grip on the resilient ribs and the valley provides tangential resistance to finger and thumb slippage thereon without the need for wings on the wire connector although if desired wings may be added to the wire connector without detracting from the invention.
While a resilient soft cover on the exterior surface of the twist-on wire connector provides a radial finger cushion the use of low profile, convex radial protruding resilient ribs on the exterior surface of the twist-on wire connector allows one to provide a tangential force to rotate the twist-on wire connector about a set of electrical wires Accordingly, a feature of the invention is that the twist-on wire connectors have an exterior surface that provides a epidermal friendly grip while inhibiting or preventing epidermal trauma on the users fingers and thumb.
With twist-on wire connectors of different diameters one spaces the ribs such that the finger contact region engages at least three ribs. Thus for larger diameter twist-on wire connectors the spacing of the ribs will be the same as for smaller diameter to ensure that at least three ribs contact each of the users fingers and thumb when the twist-on wire connector is grasped. In addition the user of shorter ribs interspersed on the base of the wire connector ensures that at least three ribs will engage a users finger and thumb. As a user grasper toward the top of the twist-on wire connector the elongated ribs become closer together since they extend longitudinally along the surface. While preferably three ribs are desired it is envisioned that more or less ribs may be engaged without departing from the spirit and scope of the invention.
Thus a feature of the invention described herein is allow one to comfortably grasp and rotate a twist-on wire connector to apply a wire securement torque regardless of the size of the twist-on wire connector while at the same time inhibiting or preventing epidermal trauma to the users fingers and thumb.
A further feature of the invention herein is the relationship of the exterior surface of the twist-on wire connector to the epidermal layer of a user's finger and thumb. Briefly in application of pressure to the twist-on wire connector the wire connector is squeezed between a users index finger and thumb. The outer epidermis layer of skin engages the surface of the wire connector with the interior dermis layer and fatty tissue provide a cushion between the bones of the index finger and the bones of the user's thumb.
The invention can provide an epidermal contact area is that eliminates edges that may rupture or injure the epidermal layer if the user grasps the twist-on wire connector to apply a wire securement torque to the twist-on wire connector. In addition to provide for an epidermal friendly grip the ribs that are compressively engaged by a users fingers and are limited from protruding from the surface of the twist-on wire connector beyond the limits of the epidermal layer to yield or flex as the wire securement torque is applied on the exterior surface of the wire connector.
Although the examples described herein disclose resilient ribs it should be understood that the same effect can be obtained through the use of sets of elongated grooves or reliefs in the resilient cover.
It will be appreciate that the invention includes an epidermal friendly method of securing a twist-on wire connector since the surfaces of the wire are free of edges or ridges that may cause epidermal trauma. Applying a wire securement torque to a twist-on wire connector involves the steps of grasping the resilient cover in the ribbed region between an epidermal layer of a users finger and an epidermal layer of a users thumb, squeezing the resilient cover to compress a portion of the resilient ribs until the epidermal layer of the users finger and the epidermal layer of the users thumb are in engagement with both a valley and a top surface of the resilient ribs without causing epidermal trauma. One can then apply the wire securement torque to the resilient cover of the twist-on wire connector while maintaining the epidermal layer of the users thumb and the epidermal layer of the users finger in pressure contact with the resilient ribs and the valley.
During the squeezing process at least a portion of three resilient ribs on diagonal opposite sides of said twist-on wire connector may be engaged to allow the user to roll the wire connector between the users finger and the users thumb during the rotating of the resilient cover to thereby bring a set of wires into electrical contact with each other.
While the epidermal friendly twist-on wire connector described herein uses a resilient cover with resilient ribs to limit epidermal trauma as well as a deformable base on the twist on wire connector it is envisioned that one may use either or both to limit epidermal trauma during the securement of a wire connection therein. It is further envisioned that in some cases the cover containing the ribs may be integral to a normally hard or rigid non-brittle shell which may rendered flexible in part by forming a thin base there beneath.
This application is a divisional application of U.S. patent application Ser. No. 12/804,412 filed Jul. 21, 2010 (now U.S. Pat. No. 8,525,026), which is a continuation in part of U.S. patent application Ser. No. 12/455,865 filed Jun. 8, 2009 (now U.S. Pat. No. 8,067,692), which is a continuation in part of U.S. application Ser. No. 11/515,465 Filed Sep. 1, 2006 (now U.S. Pat. No. 7,560,645) which is a continuation in part of U.S. patent application Ser. No. 11/249,868 filed Oct. 13, 2005 (abandoned).
Number | Name | Date | Kind |
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3519707 | Krup | Jul 1970 | A |
6478606 | McNerney | Nov 2002 | B1 |
6677530 | Blaha et al. | Jan 2004 | B2 |
Number | Date | Country | |
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Parent | 12804412 | Jul 2010 | US |
Child | 13815591 | US |
Number | Date | Country | |
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Parent | 12455865 | Jun 2009 | US |
Child | 12804412 | US | |
Parent | 11515465 | Sep 2006 | US |
Child | 12455865 | US | |
Parent | 11249868 | Oct 2005 | US |
Child | 11515465 | US |