Patent Publication Number: US-6341985-B2

Title: Connector unit having front holder

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an improved structure of a connector unit having a front holder. 
     2. Description of the Related Art 
     In a conventional connector unit  3  which includes a front holder  2  designed to cover a connector housing  1  as shown in FIGS. 7 and 8, when any of female metal terminals (hereinafter referred to as “terminal”)  4 ,  5  has become defective, it has been common that the terminal is drawn out from the connector unit  3  employing a draw jig  7  having an inserting portion  6  which is in a rectangular shape in cross section as shown in FIG.  9 . 
     A structure of the connector unit  3  will be explained hereunder; 
     The terminals  4 ,  5  are inserted into terminal receiving chambers  8  of the connector housing  1  from the back. Each of the inserted terminals  4 ,  5  is locked by a lance  10  which is abutted against a box-like portion forming a contact portion of the terminal to prevent a so-called backward withdrawal of the terminal, and firmly positioned in the connector housing. 
     On the other hand, the front holder  2  is coupled to a front of the connector housing  1  so that an interior of the connector unit  3  is completely shut from an exterior. 
     The front holder  2  of the connector unit  3  thus assembled is provided with terminal insertion holes  11  through which mating male terminals (not shown) are adapted to be inserted for electrical connection with the terminals  4 ,  5 . In addition, draw jig holes  12  in a rectangular shape similar to the inserting portion  6  of the draw jig  7  are formed in the front holder  2  adjacently to the terminal insertion holes  11 . 
     In case where the inserted terminals  4 ,  5  are electrically defective, or caulking strength at press fitted parts  9  of the terminals  4 ,  5  is weak, and so on, the terminals  4 ,  5  must be disengaged from the connector unit  3  to be replaced with new terminals, or to readjust the caulking strength. 
     In such cases, the draw jig  7  is inserted into the terminal receiving chamber  8  through the draw jig hole  12 . A distal end of the draw jig  7  has a rather pointed shape like a bow of a ship, as shown in FIG.  9 . In a first step, the distal end is abutted against a distal end of the lance  10  formed of synthetic resin (FIG.  10 A), and by further pushing the draw jig  7 , the lance  10  is forced to be elastically deformed downward from a state in FIG. 10B to a state in FIG. 10C thereby to disengage the lance  10  from the terminal. 
     In this state, the defective terminal can be drawn out backward from the terminal receiving chamber  8  and readjusted. 
     However, when the draw jig  7  is inserted into the draw jig hole  12  in a direction of an arrow A as shown in FIG. 12, and the lance  10  is forced to be elastically deformed downward to be disengaged as shown in FIG. 10, a reaction force acts on the inserting portion  6  of the draw jig  7 . Conventionally, during the terminal withdrawing operation, the reaction force has been received only by a partition wall  14  which constitutes a lower edge of tapered edges of the terminal insertion hole  11 , existing between the draw jig hole  12  and the terminal insertion hole  11 , and which is short in depth dimension. Accordingly, the partition wall  14  receives an upward deforming force from the draw jig  7  and apts to be damaged by the draw jig  7 . Moreover, when the mating terminal  15  is inserted into the terminal insertion hole  11  in a direction of an arrow B, it has been concerned that the mating terminal T may be abutted against the partition wall  14  thereby damaging the partition wall  14 . 
     If the partition wall  14  has been broken or damaged in this manner, it has been concerned that the draw jig  7  may intrude into the terminal insertion hole  11 , thereby causing a fatal damage on the female terminal  4  or  5 . 
     Further, since the draw jig hole  12  is in a rectangular shape similar to the shape of the distal end of the draw jig  7 , there has been such fears that the draw jig  7  itself may be inserted into the draw jig hole  12  upside down, whereby the lance  10  is deformed toward the terminal  4 ,  5  resulting in a damage of the terminal, or the lance  10  may bite the terminal  4 ,  5  causing the-connector unit  3  itself to be defective. 
     In view of the above drawbacks, it is an object of the present invention to provide a connector unit having a front holder in which a guide support section is formed in the draw jig hole in the front holder, thereby to minimize damages or breakdowns of the metal terminals, the front holder, the connector housing, etc. 
     SUMMARY OF THE INVENTION 
     In order to attain the above described object, there is provided, according to a first aspect of the present invention, a connector unit having a front holder comprising; 
     a connector housing which includes at least one terminal receiving chamber into which a metal terminal is inserted from a back side, the metal terminal being locked by a lance for prevention of a backward withdrawal, and 
     a front holder coupled to the connector housing from a front side, the front holder being provided with at least one terminal insertion hole into which a mating terminal is adapted to be inserted from a front side so as to be connected with the metal terminal, and at least one draw jig hole through which a draw jig is inserted from a front side to force the lance to be elastically deformed thereby to disengage a lock between the lance and the metal terminal, 
     the draw jig hole adjacent to the terminal insertion hole being provided with a guide support section which can guide the draw jig to move back and forth, and bear a reaction force from the lance acting on the draw jig when the lance is disengaged. 
     According to a second aspect of the invention, the guide support section has a determined length in a direction of back and forth movement of the draw jig, whereby the lance can be smoothly disengaged by means of the draw jig. 
     According to a third aspect of the invention, the draw jig hole has a wall at an area adjacent to the terminal insertion hole. 
     According to a fourth aspect of the invention, the draw jig hole is composed of a main hole extending away from the terminal insertion hole and lateral holes extending laterally from the main hole, while the draw jig is formed in such a shape in cross section that the draw jig can be correspondingly inserted into the main hole and the lateral holes. 
     In the connector unit having the front holder according to the first aspect of the invention, the draw jig is guided by the guide support section to move back and forth, and the guide support section receives the reaction force from the lance acting on the draw jig. 
     In the connector unit having the front holder according to the second aspect of the invention, because the guide support section has a determined length in the moving direction of the draw jig, the draw jig can smoothly move back and forth. 
     In the connector unit having the front holder according to the third aspect of the invention, because the draw jig hole has the wall at the area adjacent to the terminal insertion hole, strength of the draw jig hole will be enhanced. 
     In the connector unit having the front holder according to the fourth aspect of the invention, because the draw jig hole is composed of the main hole extending away from the terminal insertion hole and the lateral holes extending laterally from the main hole, the draw jig will not be inserted upside down into the draw jig hole by mistake. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view of a connector unit having a front holder according to one embodiment of the present invention; 
     FIG. 2 is an enlarged view of a part H of FIG. 1; 
     FIG. 3A is an enlarged perspective view of the front holder in cross section, taken along a line J—J of FIG. 2; 
     FIG. 3B is a front view for explaining a shape of a draw jig hole; 
     FIG. 4 is a perspective view of the draw jig which is adapted to be inserted into the draw jig hole (encircled is an enlarged perspective view of an essential part thereof); 
     FIG. 5 is a longitudinal sectional view of the connector unit in a state where the draw jig of FIG. 4 has been inserted into the draw jig hole; 
     FIGS. 6A,  6 B and  6 C are respective front views of the draw jig holes according to the embodiment in modified cases; 
     FIG. 7 is a front view of a connector unit having a front holder of a conventional structure; 
     FIG. 8 is a longitudinal sectional view of the connector unit in a state where the draw jig has been inserted into the draw jig hole in the connector unit of FIG. 7; 
     FIG. 9 is a perspective view of the draw jig as shown in FIG. 8 (encircled is an enlarged perspective view of an essential part thereof); 
     FIGS. 10A,  10 B, and  10 C are explanatory views showing processes in which a lance is disengaged by means of the draw jig as shown in FIG. 9; 
     FIG. 11 is a front view of an essential part of the front holder showing a positional relation between the draw jig hole and the terminal insertion hole; and 
     FIG. 12 is an enlarged perspective view of a part of the front holder of FIG. 11 taken along a like K—K, showing a state where the draw jig has been inserted into the draw jig hole. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Now, an embodiment of the present invention will be described referring to FIGS. 1 to  6 . 
     Those components substantially identical to those in the conventional structure will be represented by the same reference numerals and an explanation relating to overlapped portions will be omitted. 
     As shown in detail in FIGS. 2 and 3, a draw jig hole  13  provided in a front holder  2  adjacently to a terminal insertion hole  11  is composed of a main hole  16  extending in a direction away from the terminal insertion hole  11  and lateral holes  17  extending laterally from the main hole  16 , generally forming a convex shape or an inverted T shape. 
     A guide support section  15  is continuously formed in the rear of the draw jig hole  13  maintaining the same convex sectional shape. The guide support section  15  lies below the partition wall  14  and extends therefrom for a determined length in a direction of back and forth movement of the draw jig  7 . The guide support section  15  has the same cross sectional shape from the front face through the back face of the front holder. The guide support section  15  is constructed in such a manner that the inserted draw jig  7  can smoothly move back and forth between the lance  10  and the draw jig hole  13 , while the inserted draw jig  7  is securely supported with the least play allowing no vertical nor lateral movement around the partition wall  14  located near an inlet of the draw jig hole  13 . 
     Moreover, the draw jig hole  13  is provided with a reinforcing wall  18  at an area adjacent to the terminal insertion hole  11  to enhance strength of the draw jig hole  13 . the wall  18  extends backward to constitute a part of the guide support section. 
     In the meantime, the draw jig  7  to be inserted into the draw jig hole  13  has an inserting portion  19  which is formed in an L shape in cross section. The inserting portion  19  can be inserted into the draw jig hole  13  as shown in FIG. 2, and further inserted into the guide support section  15  thereby to disengage the lock between the terminal  4  or  5  and the lance  10 . Accordingly, due to respective shapes of the draw jig hole  13  and the draw jig  7 , it is impossible to insert the draw jig  7  upside down into the draw jig hole  13 . 
     After the terminals  4 ,  5  are assembled in the connector housing  1  as shown in FIG. 5, the front holder  2  is coupled to the connector housing  1  from the front side so as to cover it. In order to remove the terminal  4  or  5  from the thus assembled connector unit  3 , the draw jig  7  is inserted into the draw jig hole  13  in a direction of an arrow C from the front side of the front holder  2 , until the distal end of the inserting portion  19  comes in contact with the distal end of the lance  10 . Pushing further the draw jig  7  from a state in FIG. 10B to a state in FIG. 10C, the lance  10  will be disengaged from the lock with the terminal  4  or  5 . In this manner, the terminal  4  or  5  can be smoothly taken out from the terminal receiving chamber  8  of the connector housing  1  in a direction of an arrow D. 
     In the described embodiment, the draw jig  7  is guided by the guide support section  15  to be led to the lance  10 . The reaction force acting on the draw jig  7  when the lance is disengaged from the terminal  4  or  5  will be received by the guide support section  15  of the connector housing. Accordingly, such a fear that the lance or the terminal may be damaged or broken by imparting a plying force to the lance  10  through the draw jig  7  can be reliably eliminated. 
     Moreover, because the draw jig hole  13  is in a convex shape while the inserting portion of the draw jig  7  is in an L shape, insertion of the draw jig upside down can be reliably avoided. As the result, such a fear that the lance  10  may be pushed toward the terminal at the opposite side thereby damaging the lance or making the connector unit  3  itself unusable can be eliminated. 
     Further, because of the presence of the wall  18  between the terminal insertion hole  11  and the draw jig hole  13 , a shearing area of a conventional tab receiving portion E which has been F will be increased by G. As the result, the strength around the draw jig hole  13  will be substantially increased, and the partition wall  14  will not be lost or damaged. Thus, a faulty insertion of the draw jig  7  can be reliably avoided. 
     Although the present invention has been fully described referring to the embodiment, the present invention is not limited to the above described embodiment, but various changes and modifications within a scope of the invention will be included in the present invention. 
     For example, the draw jig hole  13  may be in a form of a hole  131  in an L shape as shown in FIG. 6A, in a form of a hole  132  in a trapezoidal shape as shown in FIG. 6B, or in a form of a hole  133  having a shape as shown in FIG.  6 C. The inserting portion  19  of the draw jig may be in a convex shape or an inverted T shape in cross section similarly to the draw jig hole, instead of the L shape.