Patent Publication Number: US-9837744-B2

Title: Female terminal with resilient piece having contact mark and a slide contact mark that do not overlap so that contact resistance with a male terminal is low

Description:
BACKGROUND 
     1. Field of the Invention 
     The present invention relates to a female terminal. 
     2. Description of the Related Art 
       FIG. 14  of this specification shows a known female terminal  1  with an embossed projection  3  provided on a spring portion  2  to clarify a contact position of a male terminal and the female terminal. As a male terminal  4  is inserted into the female terminal  1 , the male terminal  4  butts against a skirt portion  5  of the projection  3  when starting to move onto the projection  3 . Accordingly, a contact pressure is generated and a peak is reached while the male terminal is moving onto the projection  3 . Specifically, this peak contact pressure is larger than a contact pressure at a top portion  6 , which is a final contact position with the male terminal  4 . Thus, if a point where the contact pressure peaks and the top portion  6  are arranged very close to each other, the top portion  6  is also subject to plating wear and contact resistance on the top portion  6  may increase. Japanese Unexamined Patent Publication No. 2009-21187 discloses a female terminal that is designed to reduce an insertion force. 
     However, even if the female terminal described in Japanese Unexamined Patent Publication No. 2009-21187 can reduce an insertion force, a projecting portion to be brought resiliently into contact with the male terminal is an embossed projection and it remains unchanged that a point where a contact pressure peaks and a top portion are arranged very close to each other. Thus, there is a possibility that plating wear occurs from the point where the contact pressure peaks to the top portion and contact resistance increases. 
     SUMMARY 
     A female terminal disclosed in this specification has a resilient piece to be brought resiliently into contact with a male terminal. The resilient piece is displaceable between an initial position where the resilient piece is located before the male terminal contacts and a deformation position where the resilient piece is deformed resiliently by the contact of the male terminal therewith. A contact mark formed on a point where a contact pressure generated between the resilient piece and the male terminal is maximized and a slide contact mark formed by the slide contact of the male terminal with the resilient piece displaced to the deformation position are arranged not to overlap each other. Thus, an increase of contact resistance can be suppressed as compared to the case where the contact mark and the slide contact mark overlap each other, i.e. the contact mark and the slide contact mark are arranged very close to each other. 
     When A denotes the size of the contact mark in an arrangement direction of the contact mark and the slide contact mark, B denotes the size of the slide contact mark in the arrangement direction and C denotes a distance between centers of the contact mark and the slide contact mark in the arrangement direction, a configuration satisfying C&gt;(A+B)/2 may be adopted. 
     According to this configuration, the size A of the contact mark and the size B of the slide contact mark may, for example, be measured in advance and the distance C between the centers may be set based on the measured sizes A, B. Then, the shape of the resilient piece may be appropriately set based on the distance C between the centers. 
     According to the female terminal disclosed by this specification, it is possible to suppress an increase of contact resistance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view partly in section of a female terminal. 
         FIG. 2  is a perspective view of the female terminal viewed obliquely from front. 
         FIG. 3  is a plan view of the female terminal. 
         FIG. 4  is a side view of the female terminal. 
         FIG. 5  is a section along V-V of  FIG. 4 . 
         FIG. 6  is a front view of the female terminal. 
         FIG. 7  is a section along VII-VII of  FIG. 4 . 
         FIG. 8  is a section showing a properly connected state of a male terminal and the female terminal at the same cutting position as in  FIG. 7 . 
         FIG. 9  is a section showing a state where resilient pieces are at an initial position. 
         FIG. 10  is a section showing a state where the male terminal is in contact with each resilient piece at a contact start point. 
         FIG. 11  is a section showing a state where the male terminal is in contact with each resilient piece at a slide contact point. 
         FIG. 12  is a perspective view of a first resilient piece viewed from an oblique direction. 
         FIG. 13  is a section showing a state where the male terminal is in contact with each resilient piece at a point where a contact pressure peaks. 
         FIG. 14  is a section showing a state where a male terminal butts against a skirt portion of a projection. 
     
    
    
     DETAILED DESCRIPTION 
     An embodiment is described with reference to  FIGS. 1 to 13 . As shown in  FIG. 1 , a female terminal  10  according to this embodiment is electrically connected to a male terminal  11 . Note that, in the following description, left and right sides in  FIG. 1  are respectively referred to as front and rear sides. Further, a vertical direction is also based on  FIG. 1 . 
     (Male Terminal  11 ) 
     The male terminal  11  is formed by press-working a metal plate material into a predetermined shape. The male terminal  11  includes a male tab  12  in the form of a long and narrow plate, and contact surfaces of the male terminal  12  with the female terminal  10  are flat surfaces. Although the male terminal  11  is connected to an end of a wire in this embodiment, it may be connected to an unillustrated device. 
     (Female Terminal  10 ) 
     The female terminal  10  is formed by press-working a metal plate material into a predetermined shape. The female terminal  10  includes a tubular portion  14  into which the male tab  12  of the male terminal  11  is to be inserted. As shown in  FIGS. 2 to 4 , the tubular portion  14  is substantially in the form of a rectangular tube open in a front-back direction. The tubular portion  14  is formed by configuring a plurality of peripheral walls into a rectangular tube shape, and these peripheral walls include a bottom wall  15 , a pair of side walls  16  standing upward from both side edges of the bottom wall  15  and a ceiling wall  17  facing the bottom wall  15 . 
     The ceiling wall  17  is formed by being bent substantially at a right angle at the upper end edge of one of the pair of side walls  16  toward the other side wall  16 . A locking portion  18  is formed on a side end edge of the ceiling wall  17  and inserted into a locking hole  19  formed on the other side wall  16 . A side end edge of the other side wall  16  is folded onto the upper surface of the ceiling wall  17 . In this way, the tubular portion  14  is held to have the rectangular tube shape. 
     A wire barrel  20  extends behind the bottom wall  15 . As shown in  FIG. 1 , a core  22  exposed from an insulation coating  22  at an end of a wire  13  is connected to this wire barrel  20 . The wire barrel  20  is swaged and crimped to the core  22 . 
     (First Resilient Pieces  23 ) 
     A first base end portion  24  is formed to project on the front end edge of the bottom wall  15 . The first base end portion  24  is folded inwardly (rearwardly) of the tubular portion  14  from the front end edge of the bottom wall  15 . As shown in  FIG. 4 , the first base end portion  24  slightly projects forward from the front end edge of the tubular portion  14 . 
     As shown in  FIG. 5 , a plurality of (three in this embodiment) first resilient pieces  23  arranged side by side while being spaced apart in a direction intersecting with an inserting direction of the male terminal  11  are formed to extend inwardly (rearwardly) of the tubular portion  14  on the rear end edge of the folded first base end portion  24 . As shown in  FIG. 9 , the first resilient piece  23  extends straight in a cantilever manner from the first base end portion  24  when viewed laterally. A first contact portion  25  is formed on an extending end part of this first resilient piece  23  and resiliently contacts the male terminal  11 . For example, silver plating is applied to the first contact portion  25 . 
     Lengths of the respective first resilient pieces  23  in the front-back direction are substantially equal. Further, widths of the respective first resilient pieces  23  in a direction (hereinafter, referred to as a width direction) perpendicular to the inserting direction of the male terminal  11  are substantially equal. Further, an interval is substantially equal between each pair of adjacent first resilient pieces  23 . Thus, the plurality of first resilient pieces  23  are arranged at equal intervals substantially over the entire width of the tubular portion  14 . 
     As shown in  FIG. 7 , a contact edge  25 B of the first contact portion  25  with the male terminal  11  is arcuate. As shown in  FIG. 6 , one first contact portion  25  is formed on each first resilient piece  23 . Further, as shown in  FIG. 7 , the first contact portion  25  is formed over the entire width of the first resilient piece  23 . In this way, the contact edge  25 B of the first contact portion  25  is in point contact with the male terminal  11  in a wide range in response to a twisting movement of the male terminal  11  and a contact state is not suddenly changed by the twisting movement of the male terminal  11 . 
     (Second Resilient Pieces  26 ) 
     A second base end portion  27  is formed to project on the front end edge of the ceiling wall  17 . The second base end portion  27  is folded inwardly (rearwardly) of the tubular portion  14  from the front end edge of the ceiling wall  17 . As shown in  FIG. 4 , the second base end portion  27  slightly projects forward from the front end edge of the tubular portion  14 . 
     As shown in  FIG. 5 , a plurality of (three in this embodiment) second resilient pieces  26  arranged side by side while being spaced apart in a direction intersecting with the inserting direction of the male terminal  11  are formed to project inwardly (rearwardly) of the tubular portion  14  on the rear end edge of the folded second base end portion  27 . As shown in  FIG. 9 , the second resilient piece  26  extends straight in a cantilever manner from the second base end portion  27  when viewed laterally. A second contact portion  28  is formed on an extending end part of this second resilient piece  26  and resiliently contacts the male terminal  11 . For example, silver plating is applied to the second contact portion  28 . 
     Lengths of the respective second resilient pieces  26  in the front-back direction are substantially equal. Further, widths of the respective second resilient pieces  26  in a direction (hereinafter, referred to as a width direction) perpendicular to the inserting direction of the male terminal  11  are substantially equal. Further, an interval is substantially equal between each pair of adjacent second resilient pieces  26 . Thus, the plurality of second resilient pieces  26  are arranged at equal intervals substantially over the entire width of the tubular portion  14 . 
     As shown in  FIG. 7 , a contact edge  28 B of the second contact portion  28  with the male terminal  11  is arcuate. As shown in  FIG. 6 , one second contact portion  28  is formed on each second resilient piece  26 . Further, as shown in  FIG. 7 , the second contact portion  28  is formed over the entire width of the second resilient piece  26 . In this way, the contact edge  28 B of the second contact portion  28  is in point contact with the male terminal  11  in a wide range in response to a twisting movement of the male terminal  11  and a contact state is not suddenly changed by the twisting movement of the male terminal  11 . 
     As shown in  FIG. 6 , the first base end portion  24  and the first resilient pieces  23  and the second base end portion  27  and the second resilient pieces  26  are vertically symmetrically formed. This causes the first contact portions  25  of the first resilient pieces  23  and the second contact portions  28  of the second resilient pieces  26  to be arranged to face each other (see  FIG. 7 ). 
     (First Line Contact Portions and First Gradually Changing Portions) 
     As shown in  FIG. 12 , the first resilient piece  23  includes a first line contact portion  29  to be brought into line contact with the male terminal  11 , the first contact portion  25  to be brought into point contact with the male terminal  11  and a first gradually changing portion  30  arranged between the first line contact portion  29  and the first contact portion  25  and having a contact area with the male terminal  11  gradually reduced toward the first contact portion  25 . The first gradually changing portion  30  has a substantially isosceles triangular shape long in the front-back direction and is formed in an area extending from an end  29 B of the first line contact portion  29  to a top  25 A of the first contact portion  25 . A cutting line cutting contact surfaces  29 A,  30 A of the first resilient piece  23  with the male terminal  11  in a longitudinal direction at a position passing through the top  25 A of the first contact portion  25  along the inserting direction of the male terminal  11  is a straight line (see  FIG. 9 ). Specifically, the first gradually changing portion  30  is formed in an area not beyond a flat surface flush with the contact surface  29 A of the first line contact portion  29  (this flat surface and areas below it). Particularly, in this embodiment, the contact surface  29 A of the first line contact portion  29 , the contact surface  30 A of the first gradually changing portion  30  and the top  25 A of the first contact portion  25  are arranged side by side in a straight line in this order. 
     The contact surface  29 A of the first line contact portion  29  and the contact surface  30 A of the first gradually changing portion  30  are both flat surfaces and configured to be brought into line contact with the male terminal  11 . A length of a contact edge with the male terminal  11  is constant in the inserting direction of the male terminal  11  on the contact surface  29 A of the first line contact portion  29 , whereas a length of a contact edge with the male terminal  11  is longest at the end  29 B of the first contact portion  29 , becomes gradually shorter toward the first contact portion  25  and is shortest on the first contact portion  25  on the contact surface  30 A of the first gradually changing portion  30 . As shown in  FIG. 12 , non-contact surfaces  30 B not to be brought into contact with the male terminal  11  are formed on both sides of the first gradually changing portion  30  and these non-contact surfaces  30 B are connected to the contact edge  25 B of the first contact portion  25 . Note that the first contact portion  25  extends obliquely downward while maintaining a cross-sectional shape at the contact edge  25 B. 
     (Second Line Contact Portions and Second Gradually Changing Portions) 
     The second resilient piece  26  is configured to be vertically symmetrical with the first resilient piece  23  and includes a second line contact portion  31  to be brought into line contact with the male terminal  11 , the second contact portion  28  to be brought into point contact with the male terminal  11  and a second gradually changing portion  32  arranged between the second line contact portion  31  and the second contact portion  28  and having a contact area with the male terminal  11  gradually reduced toward the second contact portion  28 . Similarly to the first gradually changing portion  30 , the second gradually changing portion  32  has a substantially isosceles triangular shape long in the front-back direction and is formed in an area extending from an end  31 B of the second line contact portion  31  to a top  28 A of the second contact portion  28 . A cutting line cutting contact surfaces  31 A,  32 A of the second resilient piece  26  with the male terminal  11  in a longitudinal direction at a position passing through the top  28 A of the second contact portion  28  along the inserting direction of the male terminal  11  is a straight line (see  FIG. 9 ). Specifically, the second gradually changing portion  32  is formed in an area not beyond a flat surface flush with the contact surface  31 A of the second line contact portion  31  (this flat surface and areas above it). Particularly, in this embodiment, the contact surface  31 A of the second line contact portion  31 , the contact surface  32 A of the second gradually changing portion  32  and the top  28 A of the second contact portion  28  are arranged side by side in a straight line in this order. 
     The contact surface  31 A of the second line contact portion  31  and the contact surface  32 A of the second gradually changing portion  32  are both flat surfaces and configured to be brought into line contact with the male terminal  11 . A length of a contact edge with the male terminal  11  is constant in the inserting direction of the male terminal  11  on the contact surface  31 A of the second line contact portion  31 , whereas a length of a contact edge with the male terminal  11  is longest at the end  31 B of the second contact portion  31 , becomes gradually shorter toward the second contact portion  28  and is shortest on the second contact portion  28  on the contact surface  32 A of the second gradually changing portion  32 . Similarly to the first resilient piece  23 , non-contact surfaces  32 B not to be brought into contact with the male terminal  11  are formed on both sides of the second gradually changing portion  32  and these non-contact surfaces  32 B are connected to the contact edge  28 B of the second contact portion  28 . Note that the second contact portion  28  extends obliquely downward while maintaining a cross-sectional shape at the contact edge  28 B. 
     (Contact Mark and Slide Contact Mark) 
     Each resilient piece  23 ,  26  is displaceable between an initial position shown in  FIG. 9  and a deformation position shown in  FIG. 11 . The initial position is a position where the resilient piece is located before the male terminal  11  contacts each resilient piece  23 ,  26  and each resilient piece  23 ,  26  is in a natural state. Further, the deformation position is a position where each resilient piece  23 ,  26  is resiliently deformed by the contact of the male terminal  11  therewith and a contact pressure (contact load) is acting on the male terminal  11 . 
     A point where the male terminal  11  starts contacting each resilient piece  23 ,  26  located at the initial position as shown in  FIG. 10  is set as a contact start position  33 , and a point where the male terminal  11  slides in contact with each resilient piece  23 ,  26  displaced to the deformation position as shown in  FIG. 11  is set as a slide contact point  34 . As shown in  FIG. 13 , the contact pressure peaks between the contact start point  33  and the slide contact point  34 . A point where the contact pressure peaks is referred to as a point  37  where the contact pressure is maximized below. As shown in  FIG. 5 , a contact mark  35  shown in chain double-dashed line is formed around the point  37  where the contact pressure is maximized and a slide contact mark  36  shown in chain double-dashed line is formed around the slide contact point  34 . 
     Here, when A denotes the size of the contact mark  35  in an arrangement direction of the contact mark  35  and the slide contact mark  26 , B denotes the size of the slide contact mark  36  in the arrangement direction and C denotes a distance between centers of the contact mark  35  and the slide contact mark  36  in the arrangement direction (separation distance between the point where the contact pressure is maximized and the slide contact point  34  in this embodiment), the contact mark  35  and the slide contact mark  36  are arranged not to overlap each other so as to satisfy C&gt;(A+B)/2. 
     In this embodiment, the contact start point  33  matches the end  29 B,  31 B of each line contact portion  29 ,  31  and the slide contact point  34  matches the top  25 A,  28 A of each contact portion  25 ,  28 . Thus, by arranging the contact mark  35  and the slide contact mark  36  at a distance from each other, it can be suppressed that plating wear occurs at each contact portion  25 ,  28  by repeated insertion and withdrawal of the male terminal  11 . In this way, an increase of contact resistance caused by the insertion and withdrawal of the male terminal  11  can be suppressed. 
     As described above, since the contact mark  35  and the slide contact mark  36  are arranged not to overlap each other in this embodiment, an increase of contact resistance can be suppressed as compared to the case where a contact mark and a slide contact mark overlap each other, i.e. the contact mark and the slide contact mark are arranged very close to each other. 
     When A denotes the size of the contact mark  35  in the arrangement direction of the contact mark  35  and the slide contact mark  26 , B denotes the size of the slide contact mark  36  in the arrangement direction and C denotes the distance between the centers of the contact mark  35  and the slide contact mark  36  in the arrangement direction, a configuration satisfying C&gt;(A+B)/2 may be adopted. 
     According to this configuration, the size A of the contact mark  35  and the size B of the slide contact mark  36  may be, for example, measured in advance and the distance C between the centers may be set based on the measured sizes A, B. Then, the shapes of the resilient pieces  23 ,  26  may be appropriately set based on the distance C between the centers. 
     The technique disclosed by this specification is not limited to the above described and illustrated embodiment. For example, the following various modes are also included. 
     Although the contact mark  35  and the slide contact mark  36  are both shaped to be elliptical in the above embodiment, the shapes of the contact mark and the slide contact mark are not limited to elliptical shapes. Further, if the contact mark and the slide contact mark are irregularly shaped, C&gt;(A+B)/2 may not be satisfied. However, even in such a case, the contact mark and the slide contact mark have only to be arranged not to overlap each other. 
     Although the female terminal  10  in which each contact portion  25 ,  28  is not formed by embossing is illustrated in the above embodiment, even a female terminal including embossed contact portions may be adopted if a contact mark and a slide contact mark do not overlap each other. 
     LIST OF REFERENCE SIGNS 
     
         
           10  . . . female terminal 
           11  . . . male terminal 
           23  . . . first resilient piece 
           26  . . . second resilient piece 
           33  . . . contact start point 
           34  . . . slide contact point 
           35  . . . contact mark 
           36  . . . slide contact mark 
           37  . . . point where contact pressure is maximized.