Patent Publication Number: US-9899758-B1

Title: Electrical connector system with enhanced terminal retaining beam

Description:
TECHNICAL FIELD OF THE INVENTION 
     The invention generally relates to electrical connector systems, and more particularly relates to an electrical connector system having a terminal retained within a terminal receiving cavity of a connector body. 
     BACKGROUND OF THE INVENTION 
     It is common in the prior art to provide an electrical connector having a terminal received in a terminal cavity of a connector body. The terminal may be held in the connector body by flexible locking tangs or fingers. The flexible locking tangs or fingers may be formed as a part of the terminal or the connector body. Terminals having flexible locking tangs or fingers are complicated structures to manufacture, often having at least two separate pieces to be assembled and often are large and bulky. Similarly, connector bodies having flexible locking tangs or fingers are large and bulky, and are difficult to tool and injection mold. Another disadvantage of these devices having flexible locking tangs or fingers is that the system provides only a flexible locking member engaging a rigid locking member. Unfortunately, the flexible locking member may become inadvertently disengaged, allowing the terminal to be removed from the connector body. 
     U.S. Pat. No. 5,980,318 discloses an electrical connector having a terminal receiving cavity defined in part by a rigid floor wall that has a rigid lock nib that extends upwardly from the rigid floor wall into the terminal receiving cavity. A flexible beam opposes the rigid floor wall, and a ceiling wall includes a terminal hold down bump extending toward the rigid floor wall at a location generally opposite the rigid lock nib. The connector body receives a terminal in each terminal receiving cavity. Each terminal has a recess defined in part by a rigid lock bar. That is attached to side walls of the terminal. The rigid lock nib is disposed in the terminal recess when the terminal is fully seated in the terminal cavity with the rigid lock bar engaging the rigid lock nib to prevent the seated terminal from being pulled out of the terminal cavity. 
     The invention described herein provides alternatives to and advantages over the prior art. The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions. 
     BRIEF SUMMARY OF THE INVENTION 
     According to an embodiment, an electrical connector system is presented. The electrical connector system includes a first connector body that has a terminal receiving cavity formed therein. The terminal receiving cavity is defined in part by a rigid floor that has a rigid lock nib extending from the rigid floor into the terminal receiving cavity and a flexible member extending into the terminal receiving cavity overlying the rigid floor. The flexible beam has at least one fixed end secured to the first connector body and a contact portion. The contact portion has a first terminal hold down bump extending into the terminal receiving cavity and a second terminal hold down bump extending into the terminal receiving cavity distinct from the first terminal hold down bump. The electrical connector system also includes a terminal that has a first end configured to connect with a corresponding mating terminal, a second end configured to be secured to a wire, and a body portion intermediate the first and second ends. The body portion has a bottom surface that includes a rigid lock edge. The body portion has a top surface that has a first portion forward of the rigid lock edge and a second portion rearward of the rigid lock edge. The terminal is received in the terminal receiving cavity such that the first terminal hold down bump engages the first portion of the top surface and the second terminal hold down bump engages the second portion of the top surface, thereby biasing the terminal towards the rigid floor. The rigid lock nib engages the rigid lock edge, thereby preventing the terminal from being inadvertently withdrawn from the terminal receiving cavity. 
     The electrical connector system may further include a second connector body defining a connector receiving cavity. The contact portion may define a beam hold down bump located intermediate and opposed to the first and second terminal hold down bumps. The first connector body is received in the connector receiving cavity such that the beam hold down bump engages an inner surface of the connector receiving cavity, thereby further biasing the flexible beam toward the rigid floor and increasing a normal force applied by the first and second hold down bumps to the top surface of the terminal. 
     The first connector body may have a first face defining a first opening to the terminal receiving cavity for receiving the corresponding mating terminal therethrough and may have a second face defining a second opening to the terminal receiving cavity for receiving the terminal therethrough. 
     The first face may include a third opening for a channel communicating with the terminal receiving cavity. The channel is configured for insertion of an elongate tool to contact the bottom surface of the terminal in the terminal receiving cavity. The channel may be non-parallel to the rigid floor. The channel may define an acute angle relative to the rigid floor in a range of 10 to 60 degrees. The channel may enter the terminal receiving cavity forward of the rigid lock nib. 
     The first connector body may define a plurality of terminal receiving cavities. The first face may define a plurality of first openings and third openings to the plurality of terminal receiving cavities and does not define any other openings to the plurality of terminal receiving cavities. 
     The tool may be a first tool configured to confirm that the terminal is present within the terminal receiving cavity and that the bottom surface is in contact with the rigid floor. Additionally or alternatively the tool is a second tool configured to push the terminal away from the rigid floor such that the rigid lock edge disengages the rigid lock nib. 
     The first connector body may be formed by an additive manufacturing process such as stereolithography (SLA), digital light processing (DLP), fused deposition modeling (FDM), fused filament fabrication (FFF), selective laser sintering (SLS), selecting heat sintering (SHS), multi-jet modeling (MJM), or 3D printing (3DP). 
     The flexible beam may formed of a glass filled polymer material. 
     The rigid lock nib may have tapered sidewalls that engage sidewalls of the in the bottom surface of the terminal, thereby inhibiting lateral movement of the terminal in the terminal receiving cavity. 
     The terminal may be a female terminal wherein the first end is open to receive a corresponding male terminal. 
     Further features and advantages of the invention will appear more clearly on a reading of the following detailed description of the preferred embodiment of the invention, which is given by way of non-limiting example only and with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The present invention will now be described, by way of example with reference to the accompanying drawings, in which: 
         FIG. 1  is an exploded perspective view of an electrical connector system in accordance with one embodiment; 
         FIG. 2  is a cut-away side view of a first connector body of the electrical connector system of  FIG. 1  prior to insertion of a terminal in accordance with one embodiment; 
         FIG. 3  is a cut-away side view of the first connector body of  FIG. 2  after insertion of the terminal and prior to insertion of the first connector body into a second connector body of the electrical connector system of  FIG. 1  in accordance with one embodiment; 
         FIG. 4  is a cut-away side view of the first and second connector bodies of the electrical connector system of  FIG. 1  after insertion of the first connector body into the second connector body in accordance with one embodiment; 
         FIG. 5  is a cut-away end view of the a terminal receiving cavity of the first connector body of the electrical connector system of  FIG. 1  in accordance with one embodiment; 
         FIG. 6A  is a top view of the first connector body of the electrical connector system of  FIG. 1  in accordance with one embodiment; 
         FIG. 6B  is a perspective view of the first connector body of the electrical connector system of  FIG. 1  in accordance with one embodiment; 
         FIG. 6C  is a bottom view of the first connector body of the electrical connector system of  FIG. 1  in accordance with one embodiment; and 
         FIG. 6D  is an end view of the first connector body of the electrical connector system of  FIG. 1  in accordance with one embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The electrical connector system described herein includes a terminal hold down beam that is configured to apply a spring force to a terminal disposed within a terminal cavity of a first connector body to maintain engagement of the terminal with a terminal lock nib that inhibits removal of the terminal from the terminal cavity. The terminal hold down beam is also configured to contact the inside surface of a shroud of a second connector body. This contact with the shroud exerts an additional force on the terminal hold down beam that holds the terminal against a floor of the terminal cavity, thereby inhibiting relative movement between the terminal and the terminal cavity caused by vibration. 
     In the following description, terms describing orientation such as “longitudinal” will refer to the mating axis X while “lateral” should be understood to refer to an axis perpendicular to the mating axis X, which is not necessarily the transverse axis. Furthermore, other terms such as “top” or “bottom” should be understood relative to an axis perpendicular to the mating axis X, which is not necessarily the vertical axis. As used herein the terms “front” and “forward” refer to a lateral orientation referenced from the connector body towards the corresponding mating connector body and the terms “back”, “rear”, “rearward”, and “behind” refer to a lateral orientation referenced from the corresponding mating connector body towards the connector body. 
       FIGS. 1-5  illustrate a non-limiting example of an electrical connector system  10  having a first connector body  12  that holds a plurality of female electrical terminals  14  configured to terminate wire cables (not shown) and a second connector body  16  configured to mate with the first connector body  12  that holds a plurality of male electrical terminals  18  configured to interconnect with the female electrical terminals  14  within the first connector body  12 . 
     As shown in  FIG. 2 , the first connector body  12  that has a terminal receiving cavity  20 , hereinafter referred to as the terminal cavity  20 , formed therein. The terminal cavity  20  is defined in part by a rigid floor  22  that has a rigid lock nib  24  extending from the floor  22  into the terminal cavity  20 . The terminal cavity  20  also includes a flexible member  26 , hereinafter referred to as a terminal hold down beam  26 , that extends into the terminal cavity  20  and overlies the floor  22  of the terminal cavity  20 . The terminal hold down beam  26  has a fixed end  28  that is secured to the first connector body  12  and a contact portion  30  that is terminated by a free end  32  of the terminal hold down beam  26 . The free end  32  extends downwardly into the terminal cavity  20  toward the floor  22  and has a rounded end forming a first terminal hold down bump  34 . The contact portion  30  also includes a J-shaped protrusion  36  that extends downwardly from the terminal hold down beam  26  at a location rearward of the first terminal hold down bump  34 . The J-shaped protrusion  36  has a rounded end forming a second terminal hold down bump  38 . The terminal hold down beam  26  shown here is a cantilevered flexible beam but other embodiments of the invention may be envisioned in which the terminal hold down beam is a fixed flexible beam. 
     The illustrated female terminal  14  has an open end  40  that is configured to receive the corresponding male terminal  18 , an attachment end  42 , and a body portion  44  intermediate the open and attachment ends  40 ,  42 . The body portion  44  has a bottom surface  46  that includes a recess  48  or opening defined therein that is configured to receive the lock nib  24 . The recess  48  defines a rigid lock edge  50  in the bottom surface  46  with which the lock nib  24  engages. The body portion  44  also has a top surface  52  that has a first portion  54  that is located forward of the lock edge and a second portion  56  that is located rearward of the lock edge  50 . The attachment end  42  illustrated here comprises a pair of crimping wings that are configured to be mechanically crimped to the stands of the wire. Other means for attaching the wire to the terminal  14 , such as soldering or sonic welding may be used and the design of the attachment end  42  may be revised accordingly. The terminal  14  may be formed of a sheet of a conductive material, such as a tin plated copper material, by a process of stamping and bending. While the embodiment illustrated in  FIG. 2  is a female socket terminal  14  configured to receive a male blade terminal  18 , other embodiments of the electrical connector system may be envisioned using other terminal types. Further, while the terminal  14  illustrated in  FIG. 2  has a lock edge defined by a recess  48  in the bottom surface  46  of the terminal  14 , alternative embodiments may be envisioned wherein the lock edge is defined by the rear edge of the body of the terminal. 
     As the terminal  14  is received in the terminal cavity  20 , the bottom surface  46  of the terminal  14  contacts the inclined rearward surface of the lock nib  24  and the top surface  52  contacts the inclined rearward surface of the second terminal hold down bump  38 . As the terminal  14  is pushed into the terminal cavity  20 , the terminal  14  is pushed upwardly in the terminal cavity  20  by the lock nib  24  and causing the terminal hold down beam  26  to flex upwardly. After the lock edge  50  is pushed beyond the ridge formed by the junction of the rearward and forward surfaces of the lock nib  24 , the terminal  14  hold down beam  26  springs back to a partially deflected position and the lock nib  24  is received into the recess  48  such that the lock edge engages the lock nib  24 , thereby preventing the terminal from being inadvertently withdrawn from the terminal cavity  20 . When the lock nib  24  is received within the recess  48 , the first terminal hold down bump  34  engages the first portion  54  of the top surface  52  and the second terminal hold down bump  38  engages the second portion  56  of the top surface  52  and the terminal hold down beam  26  remains partially flexed and exerts a spring force on the terminal  14  through the first and second terminal hold down bumps  34 ,  38 , thereby biasing the terminal  14  towards the floor  22 . The spring force exerted on the terminal  14  by the terminal hold down beam  26  is sufficient to retain the terminal  14  within the terminal cavity  20  during the assembly of the first connector body  12  to the second connector body  16 . 
     As illustrated in  FIGS. 3 and 4 , the contact portion  30  defines a beam hold down bump  58  on the upper side of the terminal hold down beam  26  located intermediate and opposed to the first and second terminal hold down bumps  34 ,  38 . The beam hold down bump  58  extends beyond the first connector body  12 . As the first connector body  12  is received in a connector receiving cavity  60 , hereinafter referred to as the shroud  60  of the second connector body  16 , the beam hold down bump  58  compressively engages an inner surface  62  of the shroud  60 . This compressive contact between the beam hold down bump  58  and the inner surface  62  of the shroud  60  generates a compressive force on the contact portion  30  of the terminal hold down beam  26  that causes an increase in the normal force applied by the first and second hold down bumps  34 ,  38  to the top surface  52  of the terminal  14 . Without subscribing to any particular theory of operation, this increased normal force inhibits relative motion between the terminal  14  and the terminal cavity  20  that may be caused by vibration. 
     As shown in  FIG. 5 , the side walls of the lock nib  24  defines a lateral wedge  64 . The sides of the wedge  64  taper away from the side walls of the terminal cavity  20  adjacent the floor  22  and are configured to engage two sidewalls  66  of the recess in the bottom surface  46  of the terminal  14 . The sides of the wedge  64  are in intimate contact with the two sidewalls  66  of the recess  48 . Without subscribing to any particular theory of operation, the engagement of the wedge  64  with the recess  48  inhibits lateral movement of the terminal  14  within the terminal cavity  20 . In combination with the lock edge  50  which limits longitudinal motion of the terminal  14  and the terminal hold down beam  26  which limits vertical motion of the terminal  14 , the movement of the terminal  14  within the terminal cavity  20  is inhibited in three orthogonal axes. 
     Referring once more to  FIG. 4 , the first connector body  12  has a front face  68  that defines a first opening  70  to the terminal cavity  20  that is configured to for receiving the corresponding male terminal  18  therethrough and has a rear face  72  defining a second opening  74  to the terminal cavity  20  configured for receiving the terminal therethrough. The front face  68  also defines a third opening  76  for a channel  78  leading from the front face  68  to the terminal cavity  20 . The channel  78  is configured for insertion of an elongate tool  80  to contact the bottom surface  46  of the terminal  14  in the terminal cavity  20 . The front face  68  does not define any other openings to terminal cavities  20  other than first and third openings  70 ,  76 . 
     The channel  78  is non-parallel to the floor  22  of the terminal cavity  20 . The channel  78  defines an acute angle relative to the floor  22  that is in a range of 10 to 60 degrees. The channel  78  enters the terminal cavity  20  forward of the lock nib  24 . The tool  80  may be used for at least two different purposes. The tool  78  may be used to confirm that the terminal  14  is present within the terminal cavity  20  and that the bottom surface  46  is in contact with the floor  22 . The tool  80  may be a gauge that indicates the proper depth of insertion into the channel  78  at which the presence of the terminal  14  is properly detected. The tool  80  may additionally or alternatively be a conductive tool configured to test electrical continuity between and energized terminal  14  and the tool  80 . Additionally or alternatively the tool  80  may be used to push the terminal  14  away from the floor  22  such that the lock edge  50  disengages the lock nib  24 , allowing the terminal  14  to be removed from the terminal cavity  20  through the second opening  74 . Because the tool  80  is configured to contact the bottom surface  46  of the terminal  14 , the tool  80  is unlikely to cause damage to the mating surfaces  82  in the open end  40  of the terminal  14  that are accessible through the first opening. 
     The first connector body  12 , including the terminal hold down beam  26 , is preferably formed of a glass filled polymeric material. The shape of the terminal hold down beam  26  with the first and second terminal hold down bumps  34 ,  38  extending from the beam  26  would be very difficult to form using conventional injection molding technology due the complexity of the mold that would be required to form the desired shapes, therefore, the first connector body  12  is preferably formed by an additive manufacturing process such as stereolithography (SLA), digital light processing (DLP), fused deposition modeling (FDM), fused filament fabrication (FFF), selective laser sintering (SLS), selecting heat sintering (SHS), multi-jet modeling (MJM), or 3D printing (3DP). 
     While the first and second connector bodies  12 ,  16  illustrated herein define a pair of terminals  14 , cavities  20 , and associated structures, other embodiments of the connector system may be envisioned having a single terminal or more than two terminals. The more than two terminals may be arranged in several different rows and columns. 
     Accordingly an electrical connector assembly  10  is provided. The connector system  10  is configured to limiting motion of the terminal  14  within the terminal cavity  20  which provides the benefit of decreasing fretting corrosion between the terminal  14  and a corresponding mating terminal  18  of a mating electrical connector  16  due to vibration. The electrical connector assembly  10  also provides the benefit of a lower terminal insertion force since the terminal  14  only needs to overcome the spring force of the terminal hold down beam  26  when it is inserted into the terminal cavity  20  while the force exerted on the terminal  14  by the terminal hold down beam  26  is increased when the first connector body  12  is inserted within the second connector body  16  and the inner surface  62  of the shroud  60  presses down on the terminal hold down beam  26 . The angled channel  78  further provides the benefits of accessing the bottom surface  46  of the terminal  14  to verify placement of the terminal  14  in the terminal cavity  20  and removing the terminal  14  from the terminal cavity  20  without contacting the mating surfaces  82  of the terminal  14 , eliminating the opportunity to damage the mating surfaces  82  of the terminal  14  by the tool  80 . Forming the first connector body  12  using an additive manufacturing processes also allows the terminal hold down beam  26  to be shaped in a configuration that may be difficult or impossible to obtain with conventional injection molding techniques. 
     While this invention has been described in terms of the preferred embodiments thereof, it is not intended to be so limited, but rather only to the extent set forth in the claims that follow. Moreover, the use of the terms first, second, etc. does not denote any order of importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items.