Abstract:
An electrical female terminal is provided of two piece construction comprising an outer body and an inner body. The outer body has a forward shield portion and rearward conduction attaching portion. The inner body has a forward receptacle portion and a rearward conduction contacting portion enabling current to flow from a mating terminal to an attached electrical cable via the inner body. The receptacle portion includes resilient contact arms. The shield portion of the outer body surrounds the receptacle portion. The shield portion includes back-up spring members that enable the receptacle portion to maintain a normal force on a mating terminal even if the contact arms relax.

Description:
TECHNICAL FIELD 
     The present invention relates generally to electrical terminals and more specifically to tab receptacle terminals that are attached to electric cables for use in electrical connectors. 
     BACKGROUND OF THE INVENTION 
     Tab receptacle terminals having a one-piece design are described in Mobley, et al., U.S. Pat. No. 4,713,026 and Feeny, et al., U.S. Pat. No. 5,800,220. A problem with the known one-piece designs is that materials that have good electrical properties typically are not suitable for high temperature applications. High temperatures cause contact springs within the terminal to relax over time, thereby reducing retention force between the tab receptacle terminal and a mating member such as a male terminal blade or tab. This causes the current carrying capacity of the mater terminals to decrease or leads to unintended separation of the tab receptacle terminal from the mating member. 
     It is already known to provide electrical female terminals of two-piece construction comprising a terminal member and an inner spring contact member. In a known female terminal, the terminal member has a shield portion on one end and crimp wings at the other end to attach the terminal member to the end of a cable. The shield portion surrounds an inner spring contact member. 
     A problem associated with this known two-piece female terminal is that electrical current must pass through both the terminal member and the inner spring contact member. As a result, both members must be electrical conductors. In addition, both members are welded together to provide a good electrical interface. Consequently, the electrical mechanical, and weldability properties must all be considered when selecting materials for the terminal member and the inner spring contact member. This limits the materials available for selection and adds cost. Consequently, materials chosen for each member become compromises that do not ideally satisfy all of the requirements. Furthermore, an additional electrical interface is created within the terminal because the electrical current must flow between the inner spring contact member and the terminal member. 
     SUMMARY OF THE INVENTION 
     The present invention provides advantages and alternatives over the prior art with a two-piece female terminal comprising an outer body and an inner body with each piece constructed for the particular application of the piece. Importantly, the terminal is also capable of being used in high temperature environments. 
     The inner body is made of an electrically conductive material. A receptacle portion of the inner body includes a contact element which provides electrical contact to a mating terminal. The inner body extends from the receptacle portion to a conductor contacting portion enabling current to flow from the mating terminal to an attached electrical conductor via the inner body. Since the same piece provides the electrical contact for the mating terminal as well as the electrical contact to an attached conductor the electrical interfaces of the terminal are minimized. 
     The outer body includes a forward shield portion and a rearward conductor attaching portion. The inner body includes a forward receptacle portion and a rearward conductor contacting portion. The shield portion of the outer body surrounds the receptacle portion of the inner body. In a preferred embodiment, the outer body includes back-up springs that support the contact element of the inner body. The conductor attaching portion includes features for attaching the terminal to an electrical conductor such as a cable. 
     The terminal is also modular. Inner bodies made from different conductive materials can be interchanged with a particular outer body design without affecting crimp strength and other crimp properties. 
     These and other features and advantages of the present invention will become apparent from the following brief description of the drawings, detailed description, and appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  is perspective view of the terminal of the present invention. 
         FIG. 2  is an end elevational view of the terminal of the present invention. 
         FIG. 3  is a cross-sectional view of the terminal of the present invention taken along line  3 - 3  of  FIG. 2 ; and 
         FIG. 4  is a perspective view of one aspect of the terminal of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1 to 4  wherein like numerals refer to like elements throughout the several views, a preferred embodiment of a female terminal  10  of the present invention is illustrated having a two-piece construction that includes an outer body  12  and an inner body  14 . The female terminal  10  has a longitudinal axis A as shown in  FIG. 3  and a plane P as shown in  FIG. 2  extending longitudinally and laterally across the female terminal  10 . 
     The outer body  12  is stamped and formed from a metal sheet. The metal sheet is preferably stainless steel. The inner body  14  is stamped and formed from a sheet of an electrically conductive material such as brass. Other materials known to those skilled in the art may be used. Since current flows from a mating terminal through the inner body  14  to an attached conductor it is not necessary that the outer body  12  be comprised of an electrically conducting material. Alternatively, the outer body  12  can be made from an electrically conductive material. 
     The outer body  12  includes a forward, generally box shaped, shield portion  16  having a substantially rectangular cross-section, a rearward conductor attaching portion  18  and an intermediate outer body neck  20  located therebetween. The shield portion  16  includes a generally planar bottom wall  22 , first and second spaced side walls  24 ,  26  extending vertically from the bottom wall  22 , and a generally planar top wall  28  extending laterally from the first side  24 . The bottom wall  22 , the first and second spaced side walls  24 ,  26 , and the top wall  28  define an opening  29  for receiving a mating member (not shown). The top wall  28  includes a first primary lock tab  30  and a first back-up spring  32 . The first primary lock tab  30  is formed from the top wall  28  and extends outwardly. The first back-up spring  32  is constituted as individual deflectable first spring fingers  32   a ,  32   b ,  32   c  formed from the top wall  28 . Each of the first spring fingers  32   a ,  32   b ,  32   c  extend longitudinally rearwardly and are bent inwardly toward plane P. The bottom wall  22  includes a second primary lock tab  34  and a second back-up spring  36 . The second primary lock tab  34  is formed from the bottom wall  22  and extends outwardly. The second primary lock tab  34  opposes the first primary lock tab  30  across plane P. The second back-up spring  36  is constituted as individual deflectable second spring fingers (not shown) formed from the bottom wall  22 . The second spring fingers (not shown) are similar to the first spring fingers  32   a ,  32   b ,  32   c . Each of the second spring fingers (not shown) extend longitudinally rearwardly and are bent inwardly toward plane P. The intermediate outer body neck  20  extends rearwardly from the bottom wall  22  transitioning from a planar surface as it extends from the bottom wall  22  to an arcuate surface. The intermediate outer body neck  20  has a first retaining aperture  38 . The conductor attaching portion  18  extends rearwardly from the intermediate neck  20 . The conductor attaching portion  18  includes a rearward extending bottom channel portion  40 , a pair of core crimp wings  42 , an enlarged diameter portion  44 , and a pair of insulation crimp wings  46 . 
     The inner body  14  comprises a forward receptacle portion  60 , a rearward conductor contacting portion  62  and an intermediate inner body neck  64  located therebetween. The intermediate inner body neck  64  and conductor contacting portion  62  extend rearwardly as a tail from the forward receptacle portion  60 . The receptacle portion  60  of the inner body  14  is located substantially inside the shield portion  16  of the outer body  12 . The intermediate inner body neck  64  extends rearwardly from a second collar  66  of the receptacle portion  60  and is disposed along the intermediate outer body neck  20 . The conductor contacting portion  62  of the inner body  14  is disposed along the bottom channel portion  40  of the outer body  12 . The conductor contacting portion  62  is in the form of a channel  62   a  extending from the intermediate inner body neck  64  into a U-shaped region formed by the bottom channel portion  40  and core crimp wings  42 . The conductor contacting portion  62  has an arcuate shape with respect to axis A. The conductor contacting portion  62  contacts the conductive core of an electrical conductor cable (not shown) when the crimp wings  42 ,  46  are crimped onto the core and insulation of the cable (not shown). The conductor contacting portion  62  has an inwardly curved, knurled upper surface  62   b.    
     The receptacle portion  60  of the inner body  14  is adapted to fit within the shield portion  16  of the outer body  12 . The receptacle portion  60  includes the second collar  66 , a first collar  68 , a lower contact element  70 , first and second spaced sides  72 ,  74 , and an upper contact element  76 . The second collar  66  and first collar  68  each have a substantially rectangular shape with rounded corners. The first collar  68  defines an opening  77  for receiving a mating member (not shown). The upper contact element  76  of the receptacle portion  60  includes a first primary spring element  78  constituted as a resilient lamella strip with the individual upper contact arms or lamella  78   a ,  78   b ,  78   c  extending longitudinally and being bent inwardly defining respective inward facing contact surfaces  79   a ,  79   b ,  79   c . The lower contact element  70  of the receptacle portion  60  includes a second primary spring element  80  constituted as a resilient lamella strip with the individual lower contact arms or lamellae  80   a ,  80   b ,  80   c  extending longitudinally and being bent inwardly defining respective inward facing contact surfaces  81   a ,  81   b ,  81   c . The first and second sides  72 ,  74  are each constituted as a respective resilient contact arm or lamella  72   a ,  74   a  extending longitudinally and being bent inwardly defining respective inward facing contact surfaces  73   a ,  75   a . The individual upper contact lamellae  78   a ,  78   b ,  78   c  are substantially opposed to the individual lower contact lamellae  80   a ,  80   b ,  80   c  across the plane P. Each of the lamella strips  72   a ,  74   a ,  78   a ,  78   b ,  78   c ,  80   a ,  80   b ,  80   c  have a substantially rectangular cross-section with a narrowed portion  82  at each end. 
     The first back-up spring  32  is disposed outside the upper contact element  76  with the respect to plane P. Each of the individual first spring fingers  32   a ,  32   b ,  32   c  is bent inwardly toward a corresponding upper contact lamellae  78   a ,  78   b ,  78   c . Each of the individual first spring fingers  32   a ,  32   b ,  32   c  abutting and supporting corresponding upper contact lamellae  78   a ,  78   b ,  78   c  at an outward facing first contact surface  84 . The first back-up spring  32  is biased to urge the upper contact element  76  of the inner body  14  inwardly. This support helps to enable the upper contact element  76  to maintain a normal face on a mating terminal (not shown). Alternatively, there can be a gap (not shown) between the individual first spring fingers  32   a ,  32   b ,  32   c  and the corresponding upper contact lamellae  78   a ,  78   b ,  78   c . Under this alternative, if the first primary spring element  78  flattens out or relaxes over time, the gap will be eliminated and the corresponding first back-up spring  32  will abut against and support the first primary spring element  78  at the outward facing first contact surface  84  where each of the individual first spring fingers  32   a ,  32   b ,  32   c  contacts the respective upper contact lamellae  78   a ,  78   b ,  78   c.    
     Similarly, the second back-up spring  36  is disposed outside the lower contact element  70  with respect to plane P. Each of the individual second spring fingers  36   a ,  36   b ,  36   c  is bent inwardly toward a corresponding lower contact lamellae  80   a ,  80   b ,  80   c . Each of the individual second spring fingers  36   a ,  36   b ,  36   c  abutting and supporting the corresponding lower contact lamellae  80   a ,  80   b ,  80   c  at an outward facing second contact surface  86 . The second back-up spring  36  is biased to urge the lower contact element  70  of the inner body  14  inwardly. This support helps to enable the lower contact element  70  to maintain a normal face on a mating terminal (not shown). Alternatively, there can be a gap (not shown) between the individual second spring fingers  36   a ,  36   b ,  36   c  and the corresponding lower contact lamellae  80   a ,  80   b ,  80   c . Under this alternative, if the second primary spring element  80  flattens out or relaxes over time, the gap will be eliminated and the corresponding second back-up spring  36  will abut against and support the second primary spring element  80  at the outward facing second contact surface  86  where each of the individual second spring fingers  36   a ,  36   b ,  362   c  contacts the respective lower contact lamellae  80   a ,  80   b ,  80   c.    
     The intermediate inner body neck  64  has a first retaining tab  88 . The first retaining tab  88  is formed from the intermediate inner body neck  64  and extends frontwardly and outwardly. The first retaining tab  88  extends into the first retaining aperture  38  affixing the inner body  14  to the outer body  12 . A bottom portion  90  of the second collar  66  has a second retaining tab  92 . The second retaining tab  92  is formed from the bottom portion  90  of the second collar  66  and extends rearwardly and outwardly. The second retaining tab  92  extends into a second retaining aperture  94  formed near the second primary lock tab  34  further affixing the inner body  14  to the outer body  12 . Of course, the inner body  14  could also be affixed to the outer body  12  by having a retaining tab (not shown) on the outer body  12  and an aperture (not shown) for receiving the retaining tab (not shown) on the inner body  14 . Other means of affixing the inner body  14  to the outer body  12  may also occur to those skilled in the art such as by utilizing a press fit between the inner body  14  and the outer body  12 . In addition, after the female terminal  10  is crimped to the wire (not shown), the crimped wire (not shown) further holds the inner body  14  to the outer body  12 . 
     The above described features enable the shield portion  16  of the outer body  12  to be substantially symmetrical with respect to plane P. Thus, the female terminal  10  can be inserted into a connector (not shown) in two opposing orientations. 
     The above described features also enable a modular terminal in the sense that inner bodies made from different conductive materials can each be used with a particular outer body design without affecting crimp strength and other crimp properties. In addition, outer bodies made from different materials can each be used with a particular inner body design. 
     This invention has been described with reference to a preferred embodiment and modifications thereto. Further modifications and alternations may occur to others upon reading and understanding the specification. It is intended to include all such modifications and alterations insofar as they come within the scope of the invention. For example, an indexing feature familiar to those skilled in the art such as an indexing rib can be incorporated in the terminal of the present invention to enable the terminal to be inserted into a connector in only one orientation. Obviously, a tang familiar to those skilled in the art such as a latching tang can also be incorporated in the terminal of the present invention.