Abstract:
A crimp connector includes an electrically conductive curved member having an inner surface and a leading edge extending away from and back toward the inner surface. The leading edge, curved member, and inner surface define a first volume for receiving a conductive element. The electrically conductive member, in response to an external crimping force, is configured to cause the leading edge to contact and move along the inner surface until the first volume is substantially the same as a second volume defined by the portion of the conductive element received within the first volume.

Description:
BACKGROUND  
       [0001]     This invention relates to electrical connectors and more specifically to crimp connectors.  
         [0002]     Crimping is a pressure method for mechanically securing a terminal, splice or contact to a conductor. A crimping tool is generally used to physically compress (deform) a crimp barrel around the conductor in order to make the electrical connection. It is desirable for crimping to be performed in a single axial operation using a tool that is appropriately sized for the conductor and contact barrel.  
         [0003]     Referring to  FIG. 1A  and  FIG. 1B , a crimp connector  10  having a barrel  22  into which a wire is inserted is shown. The crimp connector  10  may include a fastener  12  (e.g., a rolled rail fastener) attached to the conductive barrel  22  by a transition  14 .  
         [0004]     A user inserts a wire (or other conductive element) into the conductive barrel  22  and uses a crimping tool (not shown) to permanently attach the wire to the connector  10 . Referring to  FIG. 1B , force applied by the crimping tool crimps and deforms the conductive barrel  22  from its original cylindrical shape ( 22   a ) to a flattened oval shape ( 22   b ). When the barrel  22  is crimped, the volume enclosed by the barrel  22  does not reduce to the volume of the wire (e.g., the contact point  18 ,  19  does not change significantly) which can be problematic, particularly when a wire of smaller gauge is used with the connector. Specifically, spaces  23  between the wire and conductive barrel can reduce the contact area, resulting in compromised electrical conductivity, thermal conductivity, and mechanical strength between the wire and connector  10 .  
       SUMMARY  
       [0005]     In one aspect of the invention, a crimp connector includes an electrically conductive curved member having an inner surface and a leading edge extending away from and back toward the inner surface, the leading edge, curved member, and inner surface defining a first volume for receiving a conductive element. The electrically conductive member, in response to an external crimping force, is configured to cause the leading edge to contact and move along the inner surface until the first volume is substantially the same as a second volume defined by the portion of the conductive element received within the first volume.  
         [0006]     In another aspect of the invention, a method includes the following steps. A crimp connector including an electrically conductive curved member having an inner surface and a leading edge extending away from and back toward the inner surface is provided. The leading edge, curved member, and inner surface define a first volume for receiving a conductive element. The conductive element is positioned within the first volume of the crimp connector, a portion of the conductive element positioned within the first volume defining a second volume.  
         [0007]     A crimping force is applied to the electrically conductive member sufficient to cause the leading edge to contact and move along the inner surface until the first volume is substantially the same as a second volume defined by the portion of the conductive element received within the first volume.  
         [0008]     Embodiments of the above aspects can include one or more of the following features. The inner surface includes a first section having a flat surface and a second section having an arcuate surface. The leading edge is positioned proximally to the inner surface when the crimp connector is in an uncrimped position. The leading edge can be chamfered or radiused. The crimp connector can include rib deformations extending circumferentially around the electrically conductive terminal. The rib deformations can include sharp edges. The inner surface can be connected to the rolled rail fastener and maintained in proper alignment during the crimp process by gusset elements. The electrically conductive terminal can include at least one opening which is configured to allow the positioning of an anti mis-insertion element. The conductive elements can be housed within an insulator containing an anti mis-insertion feature. The crimp connector can also include a rolled rail fastener connected to the electrically conductive curved member. The rolled rail fastener can include at least one electrically conductive crimp terminal.  
         [0009]     The conductive element can be in the form of a wire, for example, a multi-strand electrical conductor. The conductive element can be in the form of a termination or lead of an electronic component. The conductive elements can be housed within an insulator containing stress accumulators in the conductive element entry area. The stress accumulators redirect crimp forces away from dielectrically sensitive surface areas that would otherwise fracture during the crimp process.  
         [0010]     Among other advantages, deforming the barrel reduces the overall volume of the interior of the crimp barrel. The reduction of the interior volume increases the contact area of the wire to the barrel, thereby allowing a higher level of current or amperage to flow through the crimp connector without the crimp connector heating beyond an acceptable temperature. The increased contact area also provides for increased heat dissipation, thereby increasing the life and reliability of the device.  
         [0011]     The stress accumulators provide a controlled fracture and prevent the fracture from extending to a more critical area. Stress accumulators redirect crimp forces away from dielectrically sensitive surface areas that would otherwise fracture during the crimp process. 
     
    
     DESCRIPTION OF DRAWINGS  
       [0012]      FIG. 1A  is a side view of crimp connector in an un-crimped condition.  
         [0013]      FIG. 1B  is a side view of crimp connector of  FIG. 1A  in a crimped condition.  
         [0014]      FIG. 2  is a perspective view of a crimp connector.  
         [0015]      FIGS. 3A-3D  illustrate side views of the crimping process for the crimp connector of  FIG. 2 .  
         [0016]      FIG. 4  is a perspective view of the crimp connector of  FIG. 2  and a housing unit for use with the crimp connector.  
         [0017]      FIG. 5A  shows a multi-stranded wire positioned within the connector and housing unit of  FIG. 4 .  
         [0018]      FIG. 5B  is an enlarged, cross-sectional view of the conductor and the connector of  FIG. 5A .  
         [0019]      FIG. 6  is a side view of a housing unit including a stress accumulator. 
     
    
     DESCRIPTION  
       [0020]     Referring to  FIG. 2 , a crimp connector  50  is shown to include two sections: a crimp barrel  52  and a rolled-rail fastener  80 , which is electrically and mechanically connected to the crimp barrel. Crimp barrel  52  is crimpable and, as will be described in greater detail below, is shaped to accept a wire (e.g., single or multi-stranded conductor) and with the application of force deforms to establish the electrical connection to the wire. Rolled-rail fastener  80 , on the other hand, is configured to receive a bladed conductor (not shown).  
         [0021]     A transition member  74  extends between rolled-rail fastener  80  and crimp barrel  52 . A pair of conductive extensions  76  extends from the crimp barrel  52  to the fastener  80  to provide mechanical support between the barrel  51  and the fastener  80 .  
         [0022]     Referring to  FIGS. 3A-3D , transition member  74  is shaped and sized to direct a leading edge of crimp barrel  52  in a particular manner such that, in its crimped condition, any space between the wire or conductor and the volume defined by crimp barrel  52  is minimized. Put another way, upon completion of the crimping operation, the volume defined by crimp barrel  52  is substantially the same as the volume of the wire encompassed by the crimp barrel. To achieve such a crimping operation for providing an improved electrical and mechanical connection, a single axial operation causes a two-step process to be performed.  
         [0023]     As shown in  FIG. 3A , in the un-crimped condition the leading edge  68  of crimp connector  50  is proximate to an inner, gliding surface  70  of crimp barrel  52 . A user inserts a wire  90  (e.g., single or multi-strand conductor) into the crimp barrel  52  and applies a crimping force using a crimping tool (e.g., a gamma applicator press). Leading edge  68 , relative to gliding surface  70 , is slightly offset from perpendicular. Unlike the remainder of crimp barrel  52  which is substantially cylindrical, gliding surface  70  is substantially linear and flat so that, as a crimping force is applied, leading edge  68  moves along flat gliding surface  70  ( FIG. 3B ). Gliding surface  70  is flat to reduce contact friction between the gliding surface and the leading edge  68  and to minimize the possibility that the leading edge could hang-up or “stub” during crimping.  
         [0024]     The application of a crimping force causes the leading edge  68  to first move vertically upward until it contacts gliding surface  70 . During the period in which leading edge  68  moves along gliding surface  70 , the majority of the reduction in volume caused by crimping occurs. As crimping force is further applied, leading edge  68  moves beyond flat, gliding surface  70  and continues to move along inner surface  72  of crimp barrel  52 , spiraling inward until crimp barrel  52  is tightly wound around the wire ( FIG. 3C ).  
         [0025]     In preferred embodiments, leading edge  68  has a radiussed or chamfered end  69  for facilitating movement of the leading edge as it moves along inner surface  70 . In particular, when leading edge  64  reaches the gliding surface  70 , chamfered end  69  directs leading edge  68  in an upward gliding motion into gliding surface, further reducing the possibility of the leading edge stubbing against the gliding surface. Once leading edge moves beyond gliding surface  70 , leading edge continues in spiral manner until wire  90  is completely or nearly completely encircled ( FIG. 3B ). At that point, further crimping distorts the spiral shape and firmly attaches the crimp barrel  52  to the conductive element  90 . Following the spiral motion, the barrel is flattened into an oval shape ( FIG. 3D ). As will be discussed in greater detail below in conjunction with  FIGS. 5A and 5B , at this point, crimp barrel  52  includes sharp-edged ribs, which penetrate the wire.  
         [0026]     As shown in  FIGS. 3A and 3B , the crimping minimizes or virtually eliminates the space surrounding the conductor  90 . This reduction in interior volume-provides several advantages. For example, a crimp connector  50  can be used with multiple thick nesses of conductive element  90 . Reducing the interior volume increases the contact area of the wire to the electrically conductive inner surface  64 ; thus allowing higher levels of electrical current to flow through the crimp connector  50  without the crimp connector  50  heating beyond an acceptable temperature. The increased contact area also provides increased heat dissipation and a more reliable connection, reducing the likelihood of the conductor coming loose from the crimp connector  50 .  
         [0027]     The crimp connector  50  may be used with and fitted within a protective housing unit  100 . When a bladed conductor is inserted into the rolled-rail fastener  80  of the crimp connector  50 , an electric current path is provided between the wire crimped within the barrel  52  and the bladed conductor in the fastener.  
         [0028]     Referring to  FIG. 4 , protective, insulating housing  100  includes a pair of rails  102 ,  104  formed on an interior surface of the housing  100  that extend to rail fastener  80 . Upper rail  102  is received within a space  81  between opposing conductors  82   a ,  82   b  of rolled-rail fastener  80 . Crimp barrel  52  includes an opening or slot  62  (only the top slot is shown) that allows rails  102 ,  104  to extend to space  81 .  
         [0029]     Referring again to  FIG. 2  and  FIG. 5A , crimp barrel  52  includes a set of ribs  54 ,  56 ,  58 , and  60  formed on the interior surface  64  of the barrel  51  and each having sharp edges  110 . Referring to  FIG. 5B , during the crimp process, the sharp edges  110  of the ribs penetrate the surface of a wire  112  and engage the wire ensuring current flow between barrel  52  and providing a mechanically secure connection to the barrel  52 .  
         [0030]     Referring to  FIG. 6 , a crimp connector  50 ′ inserted into the insulating housing  100  is shown. In this embodiment, the insulating housing  100  includes stress accumulators  130  in a throat  132  of the wire entry  134  (only one shown). The stress accumulators  130  have a smaller cross section than adjacent areas. If the crimp action impacts the wire entry  134  area with enough force to fracture the plastic, a controlled fracture of the stress accumulators  130  occurs. The controlled fracture prevents the force from generating a fracture that could extend into more critical areas.  
         [0031]     A single stress accumulator may be included in the wire entry  134 , or multiple stress accumulators may be spaced around the wire entry  134 . To generate a controlled fracture, a set of multiple (e.g., 4, 5, 6, etc.) stress accumulators  130  may be evenly spaced within the wire entry  134 .  
         [0032]     A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.