Abstract:
An insulation displacement connector is adapted to receive an associated cable having a conductor and a covering over the conductor and secure the cable within the connector. The connector includes at least one contact. Each contact has at least one wall having a slot formed therein and defining bifurcated wall sections. The slot defines an entrance between the bifurcated wall sections. Each wall section has an outwardly inclined surface defining a reversed bevel that is contiguous with an inwardly inclined surface extending into the slot. The outwardly inclined surfaces each having a cutting edge formed thereon. A juncture of the inwardly inclined surface and its contiguous outwardly inclined surface defines an apex.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    Insulation displacement connectors are well known for connecting electrical cables to all types of components. These connectors provide for ready connection of the cable to the connector, and thus electrical connection to the component, without stripping the cable insulation, soldering the cable or the like.  
           [0002]    A typical insulation displacement connector includes an arrangement by which the insulation of the cable is severed or cut to provide direct contact between contacts of the connector and the conductor carried in the cable. The insulation is cut or severed so as to minimize any cutting of the cable.  
           [0003]    Typically, a connector includes a plastic or like polymeric body or housing that carries one or more electrical contacts. The plastic body material is an insulating material. In one conventional connector arrangement, each contact includes an elongated slot having substantially flat, opposing side walls. At an upper end of the slot, the walls are tapered inwardly from the entrance of the slot so that as the cable is urged into the slot it traverses through a narrowing or converging portion of the slot upper end. In some known contacts, the inwardly directed edges at the entrance can be coined, that is they can be provided with edges, to facilitate cutting the insulator. The remainder of the slot walls (i.e., below the entrance) are generally configured with flat surfaces (that is non-coined surfaces) to prevent otherwise cutting the conductor. Other known contacts include a flat surface at the angled or tapered entrance region.  
           [0004]    One drawback common to all of the known connectors is that as the cable insulation thickness increases, the force required to properly install or insert the cable increases. That is, the thicker the insulation, the greater the force required to insert the cable to the required depth in the contact. This is particularly true with higher voltage cables, such as 600 volt rated cables, which typically include a thicker insulation as required by code.  
           [0005]    This added force has two drawbacks. First, the connector body, which is typically plastic, must support the contact load during cable insertion. Excessive insertion forces can damage the connector body or the contact itself, thus rendering the connector useless. Second, the excessive force required to cut the thicker insulation can in turn urge the contact beams apart prematurely, thus minimizing the required electrical contact between the contact and the conductor. That is, the contact slot, which accepts the wire, is spread wider than necessary by the cable cutting force so that the contact minimally engages the conductor. This can result in less than desired, or possibly no contact between the connector contact and the conductor, again, rendering the connector useless.  
           [0006]    Accordingly, there is a need for an insulation displacement connector that includes contacts that provide electrical connection between the contacts and an associated electrical cable. Desirably, such a contact is configured to reduce the force necessary to urge the electrical cable into the contact. Most desirably, such connector contacts are configured such that they do not compromise the integrity of the electrical conductor carried within the cable. In such a contact, a counterbalancing force is exerted on the contact as the cable is urged therein so that the force exerted during insertion does not over stress the conducting portions of the contact and the connector carrying the contact.  
         SUMMARY OF THE INVENTION  
         [0007]    A reversed bevel cutting edge insulation displacement connector is adapted to receive an associated cable having a conductor and a covering, i.e., insulation, over the conductor. The connector includes at least one and preferably multiple contacts, each of which is configured to secure the cable therein, slit or cut the cable insulation and provide electrical contact between the conductor and the contact.  
           [0008]    A present insulation displacement connector provides electrical connection between the contact and an associated electrical cable, and is configured to reduce the force necessary to urge the electrical cable into the contact. Cutting edges are provided that do not compromise the integrity of the electrical conductor carried within the cable. Moreover, in the present reversed bevel connector contact, a counterbalancing force is exerted on the contact as the cable is urged therein, so as to reduce the opportunity to over stress the cutting portions of the contact and the connector housing the contact.  
           [0009]    The contact includes at least one wall, and preferably a pair of walls opposing one another. The walls can be connected to each other by an intermediate connecting section. Each wall has a slot formed therein that defines bifurcated wall sections or beams. Each slot further defines an entrance between the bifurcated wall sections. The slots of each wall align with one another.  
           [0010]    Each wall section has an outwardly inclined surface that defines a reversed bevel that is contiguous with an inwardly inclined surface extending into the slot. The outwardly inclined surfaces each having a cutting edge formed on the reversed bevel. A juncture of the inwardly inclined surface and its contiguous outwardly inclined surface defines an apex.  
           [0011]    The slot can be formed from the entrance having an elongated contacting region and an end region. Preferably, the contacting region can be defined by opposing slot walls that taper away from one another and the end region can be defined by opposing slot walls that taper toward one another. The contacting region and end region are contiguous with one another. In addition, the outward taper of the slot walls reduces the “spread” of the beams from one another when the cable is inserted into the contact. In this manner, the cable is secured in the connector slot when installed.  
           [0012]    For additional rigidity, the connector can be formed such that the walls have outer edges that taper outwardly from a juncture of the outwardly inclined surfaces at the cutting edges and the outer edges. The outward taper provides a space or buffer between the beams and the connector housing to reduce the opportunity for contact between the contact an the connector housing and possible damage to either or both.  
           [0013]    In a most preferred configuration, a distance between the apexes is greater than a greatest width of the slot. In the most preferred configuration, all of the surfaces other than the cutting edges are substantially flat surfaces. Because of the reversed bevel of the cutting edges, the insulation is cut away from the conductor, rather than toward the conductor  
           [0014]    Other features and advantages of the present invention will be apparent from the following detailed description, the accompanying drawings, and the appended claims.  
       
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0015]    The benefits and advantages of the present invention will become more readily apparent to those of ordinary skill in the art after reviewing the following detailed description and accompanying drawings, wherein:  
         [0016]    [0016]FIG. 1 is a perspective view, shown partially broken away, of an exemplary insulation displacement connector shown with a reversed tapered beveled cutting edge contact therein, embodying the principles of the present invention;  
         [0017]    [0017]FIG. 2 is a perspective view of a portion of the insulation displacement connector contact having the reversed tapered bevel;  
         [0018]    [0018]FIG. 3 is a front view of the contact of FIG. 2;  
         [0019]    [0019]FIG. 4 is a side view of the contact of FIG. 2, showing one wall of the contact;  
         [0020]    [0020]FIG. 5 is a schematic illustration showing a cable as it is urged into the contact; and  
         [0021]    [0021]FIG. 6 is a schematic illustration similar to FIG. 5 showing the cable in phantom lines and showing force arrows for expository purposes. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]    While the invention is susceptible to various embodiments, there is shown in the drawings and will hereinafter be described a specific embodiment with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiment illustrated and described.  
         [0023]    It is to be further understood that the title of this section of the specification, namely, “Detailed Description of the Invention,” relates to a requirement of the United States Patent and Trademark Office, and does not imply, nor should be inferred to limit the subject matter disclosed herein and the scope of the present invention.  
         [0024]    Referring now to the figures and in particular to FIGS.  1 - 3 , there is shown an insulation displacement connector  6  having a body  8  that carries one or more contacts  10 . Each contact  10  has reversed beveled cutting edges, indicated generally at  12 , embodying the principals of the present invention. Each contact  10  includes at least one and preferably a pair of connector walls  14 . An intermediate section  16  connects the walls  14 .  
         [0025]    Each wall  14  is formed with an elongated slot  18  therein that is configured for receiving a cable  20 . As will be recognized from the figures, the walls  14  are configured such that the slots  18  are aligned with one another when the cable  20  is received in the slots  18 . In this manner, the cable  20  goes into the slots  18  in both walls  14  and remains substantially straight, that is, unbent as it positioned in the connector  6 .  
         [0026]    Referring to FIG. 5, the cable  20  includes a conductor  22  and an outer insulating coating, or insulation  24 . Those skilled in the art will recognize that as the rating of a particular cable  20  is increased (that is as the voltage rating of the cable  20  is increased), the thickness of the insulation  24  typically increases as well. Thus, a cable that is rated for 600 volts typically has thicker insulation  24  than a comparable cable having a rating of, for example, 220 volts. Many appliance cables are in fact 600 volt rated cables. As such, the insulation  24  on these cables  20  can be quite thick and the cables  20  can be difficult to install in many known connectors.  
         [0027]    The contacts  10  of the connector  6  are configured to accommodate these higher voltage cables  20  without undue force required to urge the cable  20  into the contact  10 . Each wall  14  of the contact  10  includes the elongated slot  18  which has an entry region  26 , an elongated contacting region  28  and an end region  30 . The slot  18  bifurcates the wall  14  to define sections or beams  14   a,b  at the entry  26  and through the contacting region  28  for receiving and engaging the cable  20 .  
         [0028]    At the entry  26 , each beam  14   a,b  has an uppermost outwardly inclined or angled surface  32  and an inwardly inclined or angled surface  34 . Each of the contiguous outwardly inclined surfaces  32  and inwardly inclined surfaces  34  terminate at an apex  36 .  
         [0029]    The outwardly inclined surfaces  32  define a reversed bevel, and are formed having a coined or chamfered cutting edge  38 . The reversed bevel is shown in FIG. 3, as indicated at  40 , as against a straight line  42  extending between the apices  36 . To this end, the outwardly inclined surfaces  32  provide a cutting edge for cutting into or slitting the cable insulation  24  on either side of the conductor  22 . The inwardly inclined surfaces  34  are formed as substantially flat walls to prevent any undesirable cutting of the electrical conductor  22 . FIG. 4 illustrates best the cutting edge  38 , as well as the reversed bevel  40 .  
         [0030]    The inwardly inclined surfaces  34  terminate at a throat  44  of the slot  18 . From the throat  44 , the slot surfaces  46  angle or taper slightly outwardly, as indicated at  48  to a base region  50 . At the base region  50 , the slot  18  again tapes inwardly, as indicated at  52 , into the end region  30 .  
         [0031]    Referring to FIGS.  5 - 6 , the present contact  10  provide a number of advantages and enhancements over known connector contacts. First, it is to be understood that connectors  6  and the contacts  10  carried thereby are generally sized so that the distance between the contact apices  36 , as indicated at  54 , is less than the diameter D 20  of the cable  20  but greater than the diameter D 22  of the electrical conductor  22 . This, as will be described below, prevents inadvertently cutting into the conductor  22  when the cable  20  is urged into the contact slot  18 .  
         [0032]    As the cable  20  is positioned on the contact  10 , the apices  36  align the cable  20  over the slot  18 . As the cable  20  is urged downwardly into the slot  18 , the apices  36  provide a first point of contact and a first cutting edge for slitting the insulation  24 .  
         [0033]    Continued downward urging of the cable  20  slits or cuts the insulation  24  in an outward direction as indicated at  56 , relative to the centerline C 20  of the cable  20 . Thus, as the cable  20  is urged downwardly into the slot  18 , rather than compressing the entirety of the cable  20  across the insulation  24  through the throat  44 , the insulation  24  is cut so that there is less insulation thickness residing within the slot  18 .  
         [0034]    It will be appreciated from the figures that rather than cutting a compressed portion of the insulation  24  (that portion of the insulation  24  between the inwardly inclined surface  34 ), the cutting edges  38  contact the insulation  24  outside of this compressed area and essentially cut the insulation  24  in tension, rather than compression.  
         [0035]    In addition, unlike known contacts in which an outward force only is exerted on the wall sections as the cable is urged into the slot, in the present contact  10 , because of the reversed bevel  40  of the cutting edges  38 , there is also an inward force that is exerted on the beams  14   a,b  when the cable  20  is urged into the slot  18 , as indicated by the arrows at  58 . In this manner, rather than possibly bending the beams  14   a,b  away from one another as the cable  20  is urged downwardly, there is a counterbalancing force  58  that is exerted inwardly, that assists in overcoming the outward force generated by the downward pressure applied by the cable  20  on the beams  14   a,b.  As such, there is less tendency to bend the beams  14   a,b  outwardly away from one another.  
         [0036]    As will be recognized by those skilled in the art, if these beams or wall sections  14   a,b  are bent too far from each other, less than acceptable contact (or possibly no contact) between the contact  10  and the conductor  22  can occur. Thus, it has been observed that the present contact  10  provides enhanced electrical contact between the contact  10  and the conductor  22 .  
         [0037]    The slight outward taper  48  of the slot  18 , beyond the throat section  44 , also reduces the tendency to over-bend the beams  14   a,b  outwardly. As will be appreciated from the figures, because the distance between the surfaces in the contacting region  28  increases beyond the throat  44 , there is less force exerted (and thus less stress) on the beams  14   a,b  as the cable  20  is urged beyond the throat  44 , and into the slot  18 . As will be recognized, as the cable  20  is urged into the slot  18 , the beams  14   a,b  will bend outwardly. However, because of the taper  48 , as the beams  14   a,b  bend, the slot surfaces  46  will tend to become parallel to one another (rather than converging or diverging). It has been found that the parallel surfaces  46  provide a greater “grip” on the fully inserted cable  20 , as compared to contacts in which the surfaces have substantially converging or diverging profiles. Within the end region  30 , the inward taper  52  secures the cable  20  within the contact  10  to ensure proper engagement between the contact  10  and cable  20 , and to reduce the opportunity for the cable  20  to dislodge therefrom.  
         [0038]    Additionally, the contact  10  can be formed such that the beams  14   a,b  can be slightly tapered on an outside surface thereof, as indicated generally at  60  in FIG. 5. These outwardly tapered surfaces  60  provide a number of benefits. First, as the beams  14   a,b  are flexed or bent outwardly (by cable  20  insertion), the tapers  60  provide a space or buffer so that the beams  14   a,b  do not, or minimally contact the plastic connector body  8 . This is particularly advantageous when the cable  20  has a relatively thick insulation which can cause considerable contact beam  14   a,b  “spread”. Again, as will be recognized by those skilled in the art, because there is a greater space between the beams  14   a,b  and the connector body  8 , there is less opportunity to damage either the beams  14   a,b  or the connector body  8 , as a result of overstressed conditions. In addition, this configuration provides additional rigidity to the beams  14   a,b  against the outward bending force.  
         [0039]    In the present disclosure, the words “a” or “an” are to be taken to include both the singular and the plural. Conversely, any reference to plural items shall, where appropriate, include the singular.  
         [0040]    From the foregoing it will be observed that numerous modifications and variations can be effectuated without departing from the true spirit and scope of the novel concepts of the invention. It is to be understood that no limitation with respect to the specific embodiment illustrated is intended or should be inferred. The disclosure is intended to cover by the appended claims all such modifications as fall within the scope of the claims.