Patent Publication Number: US-9407026-B2

Title: Electrical connector with a terminal position assurance device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit under 35 U.S.C. §119(c) of U.S. Provisional Patent Application No. 62/024,051 filed Jul. 14, 2014, the entire disclosure of which is hereby incorporated herein by reference. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The invention relates to electrical connectors, and more particularly relates to an electrical connector including a terminal position assurance device having two sets of terminal locking features. 
     BACKGROUND OF THE INVENTION 
     Electrical terminals locked into a connector housing are subject to retention strength performance issues, especially with the smaller size categories of terminals (e.g. less than 2.8 mm). These smaller terminals historically have used scaled down locking features, which inherently have reduced locking retention strength and allow excessive terminal float. An excessively floating terminal can stub during mating, resulting in the terminal pushing out, and/or terminal damage especially if the retention strength within the connector housing is low. Within the automotive industry, inadequately locked terminals which pull out or push out, are recognized as the second highest root cause for failure of electrical connector systems within the vehicle warranty period. 
     Electrical connectors typically comprise internal cavities that are intended to accommodate electrical (male and/or female) terminals inserted from a rear face of the electrical connector. To ensure a well and safe functioning of the connector, it has to be ensured that the electrical terminals are locked in place within the electrical connector. 
     A solution known in the art includes providing a primary locking feature in form of a resilient retaining shoulder for preventing rearward withdrawal of the electrical terminals. The retaining shoulder, which is formed in the electrical connector, is designed to make a snap fit into a corresponding recess of the electrical connector at the end of the insertion of the electrical connector. A flexible retaining member is thereby disposed contiguously between the internal cavity and a slot, into which the retaining member can deflect. The retaining shoulder is formed on the face of the flexible retaining member that communicates with the internal cavity, such that on inserting the electrical terminal into the internal cavity, the retaining member first deflects in the slot before the retaining shoulder engages the recess of the electrical terminal. 
     In order to secure the primary locking, it is known e.g. from U.S. Pat. No. 6,132,252 to insert an additional locking member built as a rail into the slot next to the retaining member as a secondary locking. The electrical terminal being fully inserted into the internal cavity and the primary locking being engaged, the locking member is inserted into the slot from a front face of the electrical connector according to a direction corresponding to the loading direction of the electrical terminal. The retaining member is thus prevented from being flexed away from the internal cavity, thereby firmly retaining the electrical terminal. If the electrical terminal is incompletely inserted into the internal cavity, the retaining member is maintained in a deflected position into the slot, such that the locking member cannot be mounted. 
     The secondary locking mechanism known in the art requires a locking member being inserted frontward of the electrical connector in the direction opposite to that of the insertion of the electrical terminal. However, the configuration of the electrical connector may be such that a frontward insertion of the locking member is not possible, e.g. because there is not enough space at the front face side. In addition, the retaining members in connectors used with smaller terminals may easily buckle, terminal tangs may bend, and secondary locking mechanism may provide limited additional strength due to packaging constraints with terminals smaller than 2.8 mm. These solutions to date have only met the minimum terminal retention requirements, in many cases, all with little to no performance margin. 
     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 
     In accordance with an embodiment of the invention, an electrcial connector is provided. The electrical connector includes an electrical terminal and a connector housing defining a first internal cavity that extends along a longitudinal axis from a first face to a second face of the connector housing. The connector housing defines a first opening in the first face that is configured to receive the electrical terminal. The connector housing further defines a second internal cavity that extends along a lateral axis that is transverse to the longitudinal axis. The second cavity is in communication with the first cavity. The electrical connector further includes a terminal position assurance (TPA) device that is configured to be received within the second cavity. The TPA device includes a flexible primary locking feature that is configured to cooperate with a corresponding locking feature of the electrical terminal and to lock the electrical terminal in the first cavity when the TPA device is in a first position within the second cavity. The TPA device further includes a rigid secondary locking feature that is configured to cooperate with the corresponding locking feature of the electrical terminal and to lock the electrical terminal in the first cavity when the TPA device is in a second position within the second cavity. The second position is distinct from the first position. 
     The primary locking feature may be disengaged from the corresponding locking feature of the electrical terminal when the TPA device is moved to the second position. The TPA device may be configured to move from the first position to the second position along the lateral axis and transversely relative to the longitudinal axis. The TPA device may be configured to be inserted in the second cavity transversally to the first cavity through a lateral opening. 
    
    
     
       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 a perspective exploded view of a electrical connector including a movable terminal position assurance (TPA) device and a corresponding mating electrical connector in accordance with one embodiment. 
         FIG. 2A  is a exploded perspective view of the electrical connector of  FIG. 1  including the TPA device in accordance with one embodiment; 
         FIG. 2B  is a close-up view of a lateral cavity the electrical connector accommodating the TPA device of  FIG. 1  in accordance with one embodiment; 
         FIG. 3  is a front view of the TPA device of  FIG. 1  in accordance with one embodiment; 
         FIG. 4A  is a cross sectional front view of the electrical connector of  FIG. 1  with the TPA device in a terminal insertion position in accordance with one embodiment; 
         FIG. 4B  is a close-up cross sectional front view of the movable TPA device of  FIG. 1  engaging an electrical terminal while the TPA device is in the terminal insertion position of  FIG. 4A  in accordance with one embodiment; 
         FIG. 5  is a close-up cross sectional side view of the TPA device of  FIG. 1  engaging the electrical terminal while the TPA device is in the terminal insertion position of  FIG. 4A  in accordance with one embodiment; 
         FIG. 6A  is a cross sectional front view of the electrical connector of  FIG. 1  with the TPA device in a terminal locking position in accordance with one embodiment; 
         FIG. 6B  is a close-up cross sectional front view of the TPA device of  FIG. 1  engaging the electrical terminal while the TPA device is in the terminal locking position of  FIG. 6A  in accordance with one embodiment; 
         FIG. 7  is a close-up cross sectional side view of the TPA device of  FIG. 1  engaging the electrical terminal while the TPA device is in the terminal locking position of  FIG. 6A  in accordance with one embodiment; and 
         FIG. 8  is a perspective exploded view of a male electrical connector and a female electrical connector each including a TPA device in accordance with one embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Presented herein is an electrical connector including a moveable terminal position assurance (TPA) device. The TPA device secures the contacts or terminals of the connector within cavities in the connector housing once the terminals are fully inserted within the housing. The TPA device incorporates a flexible primary lock finger to engage a lock ridge of a terminal when the terminal is inserted into a cavity of a connector housing while the TPA is in an initial terminal insertion position. After insertion of all the terminals into the connector housing, the TPA is moved to a final terminal locking position. This action disengages the primary lock finger, and engages a rigid secondary lock on the TPA device. 
     Cross-referencing  FIGS. 1-7 , details of a non-limiting example of an electrical connector  10  can be seen. The electrical connector  10  is configured to mate with a corresponding mating connector  12 . A connector housing  14  of the electrical connector  10  has a first internal cavity  16 , hereinafter referred to as a terminal cavity  16 , that extends along a longitudinal axis X of the connector housing  14  from an opening  18  in a first face  20 , hereinafter referred to as an insertion end  20 , of the connector housing  14  to an opening  22  into an integral socket  24  in a second face  26 , hereinafter referred to as a mating end  26 , of the connector housing  14 . The connector housing  14  also has second internal cavity  28 , hereinafter referred to as a TPA cavity  28 , that extends along a lateral axis Y of the connector housing  14  that is transverse, or generally perpendicular, to the longitudinal axis X. As used herein, generally perpendicular is ±10° of absolutely perpendicular. This second internal cavity  28  defines a first opening  30  in a lateral wall  32  of the connector housing  14  that is configured to receive a terminal position assurance (TPA) device  34  that is configured to secure an electrical terminal  36  within the terminal cavity  16  once the terminal  36  is fully inserted within the terminal cavity  16 . The TPA device  34  is formed of a dielectric material, such as polyamide, polypropylene, or polybutylene terephthalate. At least one wall  38  of the terminal cavity  16  is open to and in communication with the TPA cavity  28 . The TPA device  34  is movable within the TPA cavity  28  from an initial position  39  before the terminal  36  is inserted into the terminal cavity  16  to a final position  41  after the terminal  36  is fully inserted within the terminal cavity  16 . 
     The TPA device  34  includes a flexible primary locking feature  40  and rigid secondary locking feature  42  each configured to secure the terminal  36  within the terminal cavity  16 . The secondary locking feature  42  is laterally adjacent the primary locking feature  40 . The TPA device  34  and the TPA cavity  28  are configured to that the TPA device  34  slides laterally within the TPA cavity  28 . The primary locking feature  40  is a flexible beam  44  that is attached at one end  46  to a cross bar  48  of the TPA device  34 . The flexible beam  44  extends along the longitudinal axis X. An unattached end  50  of the flexible beam  44  defines a ramp  52  that slopes toward the insertion end  20  of the terminal cavity  16 . The ramp  52  leads to a first lock shoulder  54  that is preferably, but not necessarily, set at a slight back angle. 
     As best shown in  FIG. 4B , the primary locking feature  40  is aligned within the terminal cavity  16  when the TPA device  34  is in the initial position  39  before the terminal  36  is inserted into the cavity  28  from the insertion end  20 . The secondary locking feature  42  of the TPA device  34  has a rigid second lock shoulder  56  defined by the cross bar  48  of the TPA device  34 . As best illustrated in  FIG. 7 , the secondary locking feature  42  may also include a rigid third lock shoulder  58  defined by the cross bar  48  of the TPA device  34 . 
     As best shown in  FIG. 6B , the secondary locking feature  42  is aligned within the terminal cavity  16  and the primary locking feature  40  is moved out of the terminal cavity  16  when the TPA device  34  is in the initial position  39  before the terminal  36  is inserted into the cavity  28  from the insertion end  20 . 
     Focusing now on a typical electrical terminal  36 , it generally includes a forward contact portion  60 , an intermediate body portion  62 , and a rearward attachment portion  64  for attaching the terminal  36  to the insulated conductor wire  66 . The body portion  62  has an inclined portion  68  that slants rearward and leads to a corresponding locking feature  70 , characterized as a first lock surface  70 . The body portion  62  also includes a flat surface  72  intermediate the inclined portion  68  and the first lock surface  70 . The body portion  62  may also include a second lock surface  74  at the end of the body portion  62  adjacent the rearward attachment portion  64 . 
     The terminal  36  is inserted into the terminal cavity  16  through the opening  18  at the insertion end  20  of the connector housing  14  when the TPA device  34  is in the initial position  39 . As best shown in  FIG. 5 , when the inclined portion  68  of the body portion  62  engages the ramp  52  of the flexible beam  44 , the inclined portion  68  deflects the flexible beam  44  so that the ramp  52  of the flexible beam  44  rides over the inclined portion  68  and flat surface  72  as the terminal  36  is further inserted within the cavity  28 . When the first lock shoulder  54  reaches the first lock surface  70 , the flexible beam  44  springs back to a generally undeflected position and the first lock shoulder of the flexible beam  44  engages the first lock surface  70  of the terminal  36 , inhibiting the terminal  36  from being pulled back out of the insertion end  20  of the connector housing  14 . 
     After the terminal  36  is fully inserted into the terminal cavity  16  and engaged with the primary locking feature  40 , the TPA device  34  is laterally moved within the TPA cavity  28  from the initial position  39  to the final position  41 . The primary locking feature  40  is moved from the terminal cavity  16  and the secondary locking feature  42  is moved into the terminal cavity  16  so that the second lock shoulder  56  now engages the first lock surface  70  and the third lock shoulder  58  engages the second lock surface  74  of the terminal  36 . 
     As illustrated in  FIGS. 1-7 , the connector housing  14  includes multiple terminal cavities  16 , so the TPA device  34  is positioned in the initial position  39  where the primary locking feature  40  holds each terminal  36  within its terminal cavity  16  until all of the terminals  36  are inserted into the terminal cavities  16 . Once all of the terminal cavities  16  are filled, the TPA device  34  is moved into the final position  41  so that the terminals  36  are held within the terminal cavities  16  by the secondary locking feature  42 . 
     Terminals  36  are preferably, but not necessarily, symmetrical about a horizontal plane so that the terminals  36  are insertable into the respective terminal cavities  16 , as best shown in  FIG. 4A , either right side up or upside down. 
     Each terminal  36  can be removed from its terminal cavity  16  by inserting a tool into an access slot and depressing the primary locking feature  40  until the first lock surface  70  is released by the first lock shoulder  54  when the TPA device  34  is in the initial position  39 . 
     While the electrical connector  10  shown in  FIGS. 1-7  is designed to contain male terminals  36 , as shown in  FIG. 8  the TPA device  34  can also be adapted for use in the corresponding mating connector  12  designed to contain female terminals. 
     Accordingly an electrical connector  10  including a TPA device  34  is provided. The TPA device  34  has the benefit of engaging multiple locking surfaces ( 56 ,  58 ) of the terminal  36  when the secondary locking feature  42  is engaged, fully locking the terminal  36  within the terminal cavity  16 . The TPA device  34  also provides a reduction of positional float of the terminal  36  within the terminal cavity  16  which greatly improves the alignment of terminals  36  within the connector housing  14  and reduces the chance of terminal push-out and/or terminal damage during connection with the corresponding mating connector  12 . Because the primary locking feature  40  is only required to hold the terminals  36  within the terminal cavities  16  during the terminal insertion process. The primary locking feature  40  may be designed to optimize the terminal insertion force without regard to final retention force since that is separately provided by the secondary locking feature  42 . This electrical  10  connector has been found to provide superior terminal retention for electrical terminals less than 2.8 mm. 
     Although the TPA device  34  in the illustrated example is configured to slide laterally within the TPA cavity  28 , other embodiments may include a TPA device that moves rotationally or helically within the TPA cavity to engage the primary or secondary locking feature with the terminal lock surfaces. 
     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.