Abstract:
A female terminal fitting has a rectangular tubular body ( 12 ) with opposed first and second walls ( 16, 17 ) and an insertion opening ( 15 ) for receiving a tab ( 11 ). An elastic contact piece ( 21 ) is inside the body ( 12 ) and extends obliquely from a support ( 27 ) on the second wall ( 17 ) of the body ( 12 ) towards both the first wall ( 16 ) and the insertion opening ( 15 ). The elastic contact piece ( 21 ) then bends back towards the second wall ( 17 ) to define an apex ( 23 ). A projection ( 30 ) projects toward the first wall ( 16 ) from a location on the elastic contact piece ( 21 ) between the support ( 27 ) and the apex ( 23 ). The elastic contact piece ( 21 ) deforms flexibly about the support ( 27 ) when the tab ( 11 ) is inserted into the body ( 12 ), thus sandwiching the tab ( 11 ) between a contact ( 31 ) of the projection ( 30 ) and the first wall ( 16 ).

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a female terminal fitting. 
   2. Description of the Related Art 
   Japanese Patent Application Laid-Open No. 2003-346958 and  FIG. 9  herein disclose a female terminal fitting. With reference to  FIG. 9 , the female terminal fitting is configured so that the tab  2  of a mating male terminal fitting can be inserted into a tab insertion opening  3  on the front surface a square pillar-shaped body  4  of the female terminal fitting. A resiliently deformable elastic contact  5  is disposed inside the body  4 . More particularly, the contact  5  is folded from the rear end of a ceiling wall  6  of the body  4  and extends obliquely forward to a bent apex  7 . The contact  5  then extends through a curve  8  and returns in a rearward direction back into contact with the ceiling wall  6 . 
   A contact projection  5 A projects from the elastic contact  5  towards a bottom wall  9  of the body part  4 . The contact projection  5 A has a contact  5 B that aligns with the apex  7  in the longitudinal direction of the female terminal fitting and is below the apex  7  in the vertical direction of the female terminal fitting. The elastic contact  5  deforms resiliently about the rear end of the ceiling wall  6  when the tab  2  is inserted into the body  4 . Thus, the tab  2  is sandwiched between the contact  5 B of the contact projection  5 A and the bottom wall  9  to connect the tab  2  electrically with the female terminal fitting. 
   A small gap is provided between the contact  5 B of the contact projection  5 A and the bottom wall  9 . Thus, the force of inserting the tab  2  into the gap is liable to increase rapidly, and an operator may have trouble fitting two housings together. 
   The present invention has been completed in view of the above-described situation. Therefore it is an object of the present invention to reduce a resistance to insertion of a tab of a female terminal fitting. 
   SUMMARY OF THE INVENTION 
   The invention relates to a female terminal fitting with a body that has an insertion opening for receiving a tab of a mating male terminal fitting so that the tab can be inserted in and pulled from the insertion opening along an axial direction of the female terminal fitting. An elastic contact is disposed inside the body and has a support connected to one wall of the body. The elastic contact extends obliquely from the support towards the insertion opening and towards an opposed wall of the body. Additionally, the elastic contact is bent at an apex. A contact projection of the elastic contact projects towards the opposed wall and deforms flexibly about the support when the tab is inserted into the body for sandwiching the tab between a contact of the contact projection and the opposed wall. 
   The contact of the contact projection preferably is at a side of the support with respect to the apex in the longitudinal direction. Thus, the tab starts to engage the contact after the tab passes the apex and the tab increases the gap between the elastic contact piece and the opposed wall. Accordingly, a force for inserting the tab into the body will not increase rapidly after the tab engages the contact and hence the tab is inserted into the body more easily. Further the contact of the contact projection is to the side of the support with respect to the apex of the female terminal fitting. Therefore it is possible to secure a stable contact pressure between the contact and the tab after the tab is inserted into the body. 
   The contact projection preferably is sloped to incline from the contact towards the insertion opening. The slope starts at a bulge start point that aligns with the apex in the axial direction or is to the side of the support with respect to the apex in the axial direction. Therefore the gap between the contact and the opposed wall becomes large when the tab is inserted into the body, and resistance to the force for inserting the tab into the body is reduced significantly. Further it is possible to secure a stable contact pressure after the tab is inserted into the body part. 
   The contact of the contact projection preferably is aligned with the apex in a direction orthogonal to the axial direction or is to the side of the support with respect to the apex in the direction orthogonal to the axial direction. Therefore, resistance to the force for inserting the tab into the body is reduced significantly and secure a stable contact pressure is achieved after the tab is inserted into the body. 
   The front end of the tab preferably is tapered and the elastic contact piece contacts the tapered surface when the elastic contact piece starts to contact the tab. Therefore the elastic contact piece starts to perform a smooth flexing operation. 
   The operation of the sliding contact between the tab and the elastic contact piece starts from the state in which the contact projection contacts the tapered surface. Therefore the elastic contact piece performs a smooth flexing operation. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a sectional side elevation showing a female terminal fitting of one embodiment of the present invention. 
       FIG. 2  is a cross-sectional view in which main portions are enlarged. 
       FIG. 3  is a vertical sectional view in which main portions are enlarged. 
       FIG. 4  is a side view showing the female terminal fitting. 
       FIG. 5  is a sectional side elevation showing a state in which a tab has not been inserted into the female terminal fitting. 
       FIG. 6  is a main portions-enlarged sectional side elevation showing a state in which a tab starts to contact an elastic contact piece. 
       FIG. 7  is a main portions-enlarged sectional side elevation showing a state in which the tab starts to perform an operation of sliding contact between the tab and a sloped portion of a contact projection. 
       FIG. 8  is a main portions-enlarged sectional side elevation showing a state in which the tab is normally inserted into a body part of the female terminal fitting. 
       FIG. 9  is a side view showing a conventional example of a female terminal fitting in which main portions are broken away. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A female terminal fitting according to the invention is identified by the numeral  10  in  FIGS. 1 through 8  and is formed by bending a conductive metal plate. The female terminal fitting  10  is long and narrow in a longitudinal or axial direction. 
   A body  12  is formed at the front end of the female terminal fitting  10  and is configured for receiving a tab  11  of a mating male terminal fitting. A wire barrel  13  is disposed rearward from the body part  12  and is configured to be caulked to an end of a core wire of a covered electric wire (not shown). An insulation barrel  14  is rearward from the wire barrel  13  and is configured to be caulked to an insulated part of the wire. The wire barrel  13  and the insulation barrel  14  have a pair of crimping pieces  13 A and a pair of crimping pieces  14 A with respect to the axis of the female terminal fitting  10 . 
   The body  12  is formed by bending the material widthwise in the shape of a square tube or pillar. An insertion opening  15  is formed on a front surface of the body  12  and is configured for receiving a male tab  11  of the male terminal fitting. 
   The body  12  has a bottom wall  16 , left and right side walls  36  that extend up from left and right sides of the bottom wall  16 , and a ceiling wall  17  that extends between the left and right side walls  36 . The ceiling wall  17  is disposed forward from the wire barrel  13 . 
   A stabilizer  18  projects up from a free end of one side wall  36  and is configured to fit in a guide groove formed in a cavity of a connector housing (not shown). The stabilizer  18  prevents the female terminal fitting  10  from being inserted into the c. 
   A locking hole  19  is formed on the ceiling wall  17  of the body  12  adjacent the stabilizer  18  (see  FIG. 1 ). A resiliently deflectable lance (not shown) is provided inside the cavity of the connector housing and can be locked to the periphery of the locking hole  19 . 
   The bottom wall  16  is struck to form a protrusion  20  with a flat top surface that extends longitudinally to allow it to slidably contact the tab  11  in a wide range and prevent the axis of the tab  11  from running out. 
   A flexibly deformable elastic contact piece  21  is folded in from a rear end of the ceiling wall  17 . More specifically, the elastic contact piece  21  has an elastic beam  22  that extends obliquely down and forward towards the bottom wall  16  from the rear end of the ceiling wall  17 . An apex  23  is disposed at a forward end of the elastic beam  22 , and the elastic contact piece  21  is bent up and forward at the apex  23 . A folded portion  24  is forward of the apex  23 . The folded portion  24  has a lower section that extends obliquely up and forward from the apex  23  and an upper section that is folded back down over the lower section. The upper and lower sections of the folded portion  24  are folded in close contact. A sliding-contact portion  25  extends obliquely up and rearward from a rear end of the folded portion  24  and a rear end of the sliding-contact portion  25  is in contact with the ceiling wall  17 . 
   A base  26  is formed at the rear of the ceiling wall  17  by striking the ceiling wall  17  down into the body part  12 . A proximal portion  27  of the elastic beam  22  overlies the base  26 . Two pieces  28  project sideways from the proximal portion  27  of the elastic beam  22  and fit in an engaging hole  37  on the corresponding side wall  36  for preventing excessive upward movement of the elastic contact piece  21 . 
   The length of the elastic beam  22  in its longitudinal direction is set to ensure a smooth elastic operation of the elastic contact piece  21 . The apex  23  is at the front end of the elastic beam  22  and nearest to the bottom wall  16 . A front surface of the folded portion  24  is disposed to face the insertion opening  15  and functions as a tapered guide  29  for guiding the tab  11  to a normal insertion position. 
   A flat and dome-shaped projection  30  bulges from a lower surface of the elastic beam  22  of the elastic contact piece  21  toward the protrusion  20  of the bottom wall  16 . The projection  30  is formed by striking down the elastic beam  22 . The projection  30 , when viewed from below, extends longitudinally and has a generally elliptical shape that is gradually narrower towards the front, as shown in  FIG. 2 . 
   The projection  30  has an inclined surface  38  (see  FIGS. 5 and 6 ) that inclines gently rearward from a front end thereof A contact  31  is formed at a rear side of the inclined surface  38  and is configured for contacting the tab  11 . A region of the projection  30  rearward from the contact  31  inclines steeply toward the elastic body  22 , and a rear end thereof is continuous with a lower surface of the elastic beam  22 . The contact  31  is located about ⅔ of the whole length from a front end of the contact  30  to the rear end thereof. 
   A bulge start point  32  is formed at the front end of the inclined surface  38  substantially at the apex  23  and at the front of the projection  30 . Therefore the projection  30  is midway in a region where the interval between the elastic beam  22  and the bottom wall  16  increases. The contact  31  of the projection  30  is slightly lower than the apex  23  in a vertical direction, and hence in a direction orthogonal to the axis of the female terminal fitting  10 . The interval between the contact  31  and the protrusion  20  opposed thereto is smaller than the thickness of the tab  11 , but to an extent so that an operator does not feel excessive resistance while inserting the tab  11  into the body  12 . 
   The tab  11  initially is inserted into the body  12  from the front of the female terminal fitting  10  through the insertion opening  15 . As a result, as shown in  FIG. 6 , a forward taper  34  of the tab  11  contacts the guide surface  29  of the elastic contact piece  21 . Consequently the elastic contact piece  21  deforms flexibly about the proximal portion  27  of the elastic beam  22 , and the rear end of the sliding-contact portion  25  slides rearward along the inner surface of the ceiling wall  17 . 
   The taper  34  of the tab  11  slides smoothly rearward on the guide  29  of the elastic contact piece  21 , and hence the elastic contact piece  21  is pressed up. As shown in  FIG. 7 , the taper  34  of the tab  11  eventually passes the apex  23  and reaches a position corresponding to the projection  30 . Thus, the taper  34  of the tab  11  strikes the inclined surface  38  of the projection  30  in a face contact. Further insertion of the tab  11  into the body  12  causes the taper  34  of the tab  11  to move to the contact  31  along the inclined surface  38  of the projection  30 . 
   The gap between the contact  31  of the elastic contact piece  21  and the protrusion  20  increases as the tab  11  is inserted. However, the amount of flexible displacement of the elastic contact piece  21  is small because the gap is set widely. A planar peripheral surface  39  of the tab  11  rearward of the taper  34  slidably contacts the contact  31  after the taper  34  of the tab  11  rides across the inclined surface  38  and passes the contact  31 . In this manner, as shown in  FIG. 8 , the tab  11  reaches the normal insertion position. Thus, the tab  11  is connected electrically with the female terminal fitting  10 , and is sandwiched between the contact  31  of the elastic contact piece  21  and the protrusion  20 . 
   The contact  31  of the projection  30  is rearward from the apex  23 . Thus, the tab  11  passes the apex  23  and starts to engage the contact  31 , while increasing the gap between the elastic contact piece  21  and the bottom wall  16 . Movement of the tab  11  to and beyond the contact  31  does not cause a rapid increase of the force for inserting the tab  11  into the body  12  because the amount of flexible displacement of the elastic contact piece  21  is small. Consequently, an operator can connect the male and female housings easily. Further the contact  31  of the contact  30  is between the apex  23  and the proximal portion  27  about which the elastic contact piece  21  flexes. Therefore, a stable contact pressure of elastic contact piece  21  against tab  11  is achieved after the tab  11  is inserted into the body  12 . 
   The bulge start point  32  of the projection  30  is coincident with the apex  23  in the axial direction of the female terminal fitting  11 . Therefore, the gap between the contact  31  and the protrusion  20  becomes large when the tab  11  is inserted into the body part  12  and the resistance to the insertion of the tab  11  into the body  12  is reduced significantly. Further, the contact  31  of the projection  30  is slightly lower than the apex  23 . Thus, the flexible displacement amount of the elastic contact piece  21  is reduced, and resistance to the insertion of the tab  11  into the body  12  is decreased significantly. 
   Further, the taper  34  of the tab  11  and the guide surface  29  of the elastic contact piece  21  slidably contact each other at the start time of the insertion of the tab  11  into the body  12 . Thus the elastic contact piece  21  flexes smoothly. 
   Further the operation of sliding between the taper  34  of the tab  11  and the inclined surface  38  of the projection  30  starts with the taper  34  and the inclined surface  38  in the face contact. Thus, the elastic contact piece  21  flexes smoothly. 
   The invention is not limited to the above-described embodiment described above with reference to the drawings. For example, the following embodiments are included in the technical scope of the present invention. Further, various modifications of the above-described embodiment can be made without departing from the spirit and scope of the present invention. 
   In the above-described embodiment, the proximal portion of the elastic contact piece is connected with the ceiling wall. However, the elastic contact piece may be separate from the body and the proximal portion thereof may be connected with a mounting portion of the ceiling wall by press fit or the like. 
   In the above-described embodiment, the proximal portion of the elastic contact piece is connected with the ceiling wall. But in the present invention, the proximal portion of the elastic contact piece may be connected with the bottom wall. 
   In the above-described embodiment, the bulge start point of the projection is coincident with the apex in the longitudinal direction of the female terminal fitting. However, the bulge start point of the projection may be rearward from the apex to reduce the resistance to the insertion of the tab into the body. 
   In the above-described embodiment, the bulge start point of the projection is slightly lower than the apex in the vertical direction. However, the bulge start point of the projection may be coincident with the apex or to the side of the proximal portion with respect to the apex in the vertical direction. Thus, the gap between the contact portion and the protrusion is large. Therefore, it is possible to reduce the resistance to the insertion of the tab into the body and to secure a stable contact pressure after the tab is inserted into the body part.