Abstract:
An improved box-shaped female electrical connector featuring an optimized conductive (electrical and thermal) path, a spring contact insensitive to deformation, minimization of male blade insertion force, and maximization of contact force with the blade, all made possible by inclusion of the following structural aspects: an optimized conductive path, a spring contact carried by a dual spring contact member operative interfaced with an over stress abutment, a spring contact shield at the mouth of the electrical connector, and a basal contact, disposed opposite the spring contact, which is part of the direct conductive path of the electrical connector.

Description:
TECHNICAL FIELD 
   The present invention relates to electrical connectors, and more particularly to female electrical connectors including a spring contact and oppositely disposed basal contact for electrically interfacing with a male blade terminal. Still more particularly, the present invention relates to an electrical connector of the aforesaid class having an optimized conductive path. 
   BACKGROUND OF THE INVENTION 
   In the electrical arts, it has been the practice to provide a selectively separable electrical connection between first and second electrical circuits by mutually interfacing first and second electrical connectors, each being respectively connected to the first and second electrical circuits. In this regard, of particular interest are box-shaped female electrical connectors having an internally disposed resilient spring contact and opposingly disposed basal contact for engaging an inserted male blade. An interesting example of such an electrical connector is recounted in U.S. Pat. No. 5,281,175. 
   A number of concerns exist with respect to the aforementioned class of female electrical connectors, including: improving electrical conductivity of the conductive path; minimizing spring terminal deformation sensitivity; and minimizing male blade insertion force while concomitantly providing high contact force with respect thereto. 
   Accordingly, it would be most desirable if somehow a box-shaped female electrical connector could be devised wherein the conductive path is optimized, the spring contact terminal thereof is insensitive to deformation, male blade insertion is minimized and contact force with the male blade is maximized. 
   SUMMARY OF THE INVENTION 
   The present invention is an improved box-shaped female electrical connector featuring an optimized conductive (electrical and thermal) path, a spring contact insensitive to deformation, minimization of male blade insertion force, and maximization of contact force with the blade, all made possible by inclusion of the following structural aspects: an optimized conductive path, a spring contact carried by a dual spring contact member operatively interfaced with an over stress abutment, a spring contact shield at the mouth of the electrical connector, and a basal contact, disposed opposite the spring contact, which is part of the direct conductive path of the electrical connector, all of which allowing use of thinner connector body metal and enhanced connector performance. 
   The improved female electrical connector according to the present invention has a connector body integrally composed of a connector portion, a crimp portion, and a transition portion disposed therebetween. The connector portion includes has generally box-shape defining an interior cavity, and is characterized by an upper wall, an opposite lower wall and sidewalls extending therebetween. The forward end of the electrical connector body has a mouth into which a male blade is insertable. Disposed oppositely with respect to the mouth, at the distal end of the connector body, is the crimp portion, characterized by a first wire core crimp and a wire jacket crimp both integrally formed of the connector body. 
   A portion of the lower wall is folded 180 degrees back on itself at the mouth to thereby provide a leg disposed adjacent the lower wall of the electrical connector body. The distal end of the leg has an integrally formed second wire core crimp which is nested with respect to the first wire core crimp of the lower wall. The leg carries a basal contact, preferably provided by a raised land of the leg. 
   A dual spring contact member is composed of a spring arm which originates at a spring beam that is integrally connected to the electrical connector body, and is disposed in the interior cavity generally adjacent the mouth. A generally bow shaped primary spring carries a spring contact and is disposed between a primary nose and a secondary nose, wherein the spring contact is disposed opposite the basal contact of the leg. Connected to the secondary nose is a secondary spring having a distal end which abuts the upper wall. 
   A mouth shield is formed of the upper wall and serves to protect the primary nose of the dual spring contact member from insertional damage as a male blade terminal is inserted into the electrical connector body. 
   A lug depends from the upper wall, and serves as an abutment for the spring arm in the event the dual spring contact member is over stressed by a male blade that has been inserted through the mouth. 
   In operation, a male blade is inserted into the electrical connector body of the electrical connector through the mouth thereof, wherein, as the male blade is inserted, it slidingly abuts the spring contact and the opposing basal contact. The primary and secondary springs of the dual spring contact member are resiliently compressed by the male blade, thereby assuring a strong contact force between the male terminal and the spring and leg contacts, while the insertional force applied to the male blade is minimized. 
   The primary spring and the secondary spring perform independently of each other. Accordingly, in the event the primary spring should become damaged, as for example if the male blade terminal untowardly bent the primary spring, then the secondary spring will function normally and independently of the primary spring so as to provide excellent electrical contact of an inserted male blade with the spring contact. 
   The leg provides a direct electrical path between the second wire core crimp and the basal contact, whereby electrical resistance is minimal therebetween, and the combination of the leg and the lower wall provide an optimized conductive path for electricity and heat dissipation. Further the leg provides strengthening at the transition portion between the connector portion and the crimp portion of the connector body. 
   Accordingly, it is an object of the present invention to provide an improved box-shaped female electrical connector featuring an optimized conductive path, a spring contact insensitive to deformation, minimization of male blade insertion force, and maximization of contact force with the blade. 
   This and additional objects, features and advantages of the present invention will become clearer from the following specification of a preferred embodiment. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective, forward facing view of an electrical connector according to the present invention. 
       FIG. 2  is a perspective, rearward facing view of the electrical connector of  FIG. 1 . 
       FIG. 3  is a longitudinal section view of the electrical connector of  FIG. 1 . 
       FIG. 4  is a sectional view of the electrical connector as in  FIG. 3 , now seen in operation with respect to a crimped wire core and an inserted male blade. 
       FIG. 5  is a partly broken-away front view of the electrical connector, seen along line  5 - 5  of  FIG. 3 . 
       FIG. 6  is a sectional view of the electrical connector shown in operation, seen along line  6 - 6  of  FIG. 4 . 
       FIG. 7  is a plan view of a metal blank which is selectively bent to form the electrical connector according to the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the Drawing,  FIGS. 1 through 7  depict various aspects of an electrical connector  100  having a dual conductive (electrical and thermal) path in accordance with the present invention. The electrical connector  100  is formed of a single piece metal blank (see  FIG. 7 ) which is formed into a connector body  110  (to be described hereinbelow), wherein the connector body has a connector portion  112  and a crimp portion  114  which are integrally interfaced via a transition portion therebetween, as further discussed hereinbelow. 
   The connector portion  112  has a generally box-shape defined by an upper wall  116 , an opposite lower wall  118  and left and right sidewalls  120 ,  122  extending therebetween, collectively defining an interior cavity  124 . A forward end  126  of the connector portion  112  has a mouth  128  for receiving a male blade (see for example  FIG. 4 ) into the interior cavity  124 . 
   A dual spring contact member  130  is composed of a spring arm  132  which is integral with the connector body  110 , wherein a spring beam  134  originates at the left sidewall  120  (or alternatively may originate at the right sidewall  122 ) at a location spaced from the mouth  128  (as seen best at  FIG. 3 ). The spring beam  134  extends toward a primary nose  136  disposed adjacent the mouth  128 . The primary nose  136  is defined by a first 180 degree bend in the spring arm  132 . Connected to the primary nose  136 , opposite the spring beam  134 , is a generally bow shaped primary spring  138  which is disposed inside the interior cavity  124  and extends rearwardly from the mouth  128  in spaced relation from the upper and lower walls  116 ,  118 . A medial portion of the primary spring  138  serves as a spring contact  140 . Connected to the primary spring  138 , opposite the primary nose  136 , is a secondary nose  142 . The secondary nose  142  is defined by a second 180 degree bend in the spring arm  132 . Connected to the secondary nose  142 , opposite the primary spring  138 , is a secondary spring  144 . The secondary spring  144  bends toward, and abuts at a terminus  144   a  thereof, the upper wall  116  of the connector portion  112 . 
   Disposed oppositely with respect to the spring contact  140  of the dual spring contact member  130  is a basal contact  150 , preferably in the form of a raised land. The basal contact  150  is formed of a leg  152 . The leg  152  is integrally connected with the connector body  110  at the lower wall  118 , wherein at the mouth  128 , the leg is folded 180 degrees back on itself, thereby forming leg nose  154 , whereby the leg is disposed in the interior cavity  124  adjacent the lower wall. 
   A mouth shield  160  is integrally connected with the upper wall  116  at the mouth  128  and is downwardly depending so as to partly occlude the mouth with respect to the primary nose  136  of the dual spring contact member  130 . The mouth shield  160  serves to protect the primary nose  136  from possible damage by a male blade  164  as it is inserted into the interior cavity (see generally  FIG. 4 ). 
   An overstress lug  170  is integrally connected with the upper wall  116  and depends therefrom in generally close proximity to the mouth  128 . The overstress lug  170  terminates at a lug abutment  172  which is spaced in proximal relation to the spring beam  134 . In the event of an overstress compression of the dual spring contact member  130  by insertion of a male blade, the spring beam  134  will abut the lug abutment  172  and thereby greatly stiffen the primary spring  138  at the primary nose  136  and thereby prevent the primary spring from exceeding its elastic limit where the spring beam  134  originates at the left sidewall  120  (or alternatively at the right sidewall  122 ). 
   The crimp portion  114  is integrally connected to the connector portion  112  at the lower wall  118  at a body transition portion  180 . The crimp portion  112  includes a first wire core crimp  182  and a wire jacket crimp  184  both integrally formed of the connector body  110 . 
   Distally from the mouth  128 , the leg  152  forms a second wire core crimp  186  which is nested with respect to the first wire core crimp  182 . There is a leg transition portion  188  of the leg  152  which is nested with respect to the body transition portion  180 , wherein this nesting provides stiffening of the connector body  110  at the body transition portion  180 , whereby metal thickness of the connector body (blank) may be reduced, ie., from, for example, 0.3 mm thickness to 0.2 mm thickness. 
   An optimized conductive path  198  for electrical and thermal conduction is provided by the leg  152  and the lower wall  118 . The optimized conductive path  198  allows for minimal electrical resistance and excellent heat dissipation by the conductor body  110 . A direct electrical path  190  is provided between the second wire core crimp  186  and the basal contact  150 . 
   Additionally, the nested first and second wire core crimps provide a dual electrical path between a crimped wire core  192  of a wire  194  and the spring and leg contacts  140 ,  150  (see  FIG. 4 ), whereby electrical resistance and Joule heating of the electrical connector  100 , when in operation, is minimized even where the metal thickness has been reduced, as mentioned above. 
   Turning attention now with particularity to  FIG. 7 , seen is a single piece, die-cut metal blank  200  to which bending and stamping operations provide the aforedescribed connector body  110 . In this regard, like parts as described above will be identified on the metal blank  200  with like numbers with a prime. The operations described below may not be performed in the order described. 
   The blank  200  includes the connector portion  112 ′, the crimp portion  114 ′ and body and leg transition portions  180 ′,  188 ′. The connector portion  112 ′ is formed by the leg  152 ′ being stamped within stamp lines S 1  to provide the raised land of the basal contact  150 ′, and the distal end of the leg is bendingly provided with the second wire core crimp  186 ′ and the leg transition portion  188 ′. The leg  152 ′ is then bent 180 degrees back at fold A to form the above discussed leg nose. The right side wall  122  is formed by a 90 degree bend along fold B. The spring arm  132 ′ is bent, including at folds C, D, E (forming the secondary nose) and F (forming the primary nose), with the spring contact  140 ′ being located between folds E and F, to provide the above described dual contact spring member. The overstress lug  170 ′ is formed by a die cut H and a 90 degree bend at fold I. The mouth shield  160 ′ is formed by a 90 degree bend at fold J. The recessed spring abutment land  146 ′ is provided by stamping within stamp lines S 2 . The left sidewall  120  is formed by a 90 degree bend at fold G, and the upper wall  116 ′ is formed by a 90 degree bend at fold K. Bends of 90 degrees are provided at folds L and M. Finally, the connector body  110 ′ is completed by bending to provide the first wire core crimp  182 ′ and the wire jacket crimp  184 ′. 
   With particular reference to  FIGS. 4 and 6 , operation of the electrical connector  100  will now be detailed. 
   A male blade  164  is inserted into the conductor body  110  of the electrical connector  100  through the mouth  128  thereof, wherein, as the male blade is inserted, it abuts the spring contact  140  of the dual spring contact member  130  and the opposing basal contact  150  of the leg  152 . The primary and secondary springs  138 ,  144  of the dual spring contact member are resiliently compressed, thereby assuring a strong contact force between the male terminal  164  and the spring and basal contacts  140 ,  150 , while easing the insertional force of the male blade into the interior cavity  124 . 
   The leg  152  provides a direct electrical path  190  between the second wire core crimp  186  and the basal contact  150 , and, in combination with the lower wall  118  provides an optimized conductive path  198  for both electricity and heat, whereby electrical resistance and Joule heating are minimal, and any heat is readily dissipated by being conducted away throughout the conductor body  110 . Further the leg provides strengthening at the body and leg transitions  180 ,  188  disposed between the connector portion  112  and the crimp portion  114  of the connector body  110 . 
   The primary and secondary springs  130 ,  144  provide resilient location of the spring contact  140  independent of each other. In the event the primary spring  130  should become damaged, as for example by being bent by an untoward insertion of a male blade, then the undamaged secondary spring  144  will function normally and independently of the damaged primary spring so as to provide excellent electrical contact of the inserted male blade with the spring contact  140  and the basal contact  150 . The primary and secondary springs  130 ,  144  allow accommodation for various thicknesses of male blades, which eliminates need for different sized electrical connectors for differing sized male blade terminals. The spring contact will compliantly follow the surface movement of the male blade, and the electrical contact therebetween is vibration insensitive. 
   It will be understood that the embodiment shown and described above with respect to an electrical connector having nested first and second wire core crimps is by way of exemplification only and not limitation. It is possible, for example, to connect the second wire core crimp to the connector body other than via a leg, as described and shown, such as for example by connection of the second wire core crimp to the upper wall, either or both of the left and right sidewalls, or otherwise with respect to the bottom wall. 
   To those skilled in the art to which this invention appertains, the above described preferred embodiment may be subject to change or modification. Such change or modification can be carried out without departing from the scope of the invention, which is intended to be limited only by the scope of the appended claims.