Patent Publication Number: US-6702614-B2

Title: Connector with lock configured to avoid interference with terminal fitting

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a connector. 
     2. Description of the Related Art 
     A known connector is disclosed in U.S. Pat. No. 5,235,743 and also is illustrated in FIG. 17 herein. With reference to FIG. 17, the connector has a housing  1  and a terminal fitting  2  inserted from behind into a cavity  3  of the housing  1 . The housing  1  has a lock  4  that defines the bottom of the cavity  3 . The lock  4  has a long arm  4   a  that is resiliently deformable along the vertical direction. A fastening projection  4   b  projects from the upper surface of the arm  4   a  and is fittable into a hole  2   a  in the bottom wall of the terminal fitting  2  to engage the edge of the hole  2   a.    
     The connector of FIG. 17 can be miniaturized by reducing the size of all components. However, the smaller lock  4  is weaker and may be deformed by an excessive pulling force on the locked terminal fitting  2 . As a countermeasure, a locking surface  5  of the fastening projection  4   b  can be inclined at an obtuse angle with respect to a withdrawing direction, as shown in FIG.  18 . This inclination of the locking surface  5  causes a component of the pulling force on the locked terminal fitting  2  to act in a direction opposite from the deforming direction. Thus, the lock  4  is difficult to disengage, and the force to lock the terminal fitting  2  can be increased. 
     The inclination of locking surface  5  creates problems when the terminal fitting  2  is being detached. Specifically, the terminal fitting  2  is detached by forcibly deforming the lock  4  with a disengagement jig. However, the locking surface  5  is inclined forward toward its upper end and a trace of displacement of the locking surface  5  during the resilient deformation is more forward than that of FIG.  17 . Thus, the locking surface  5  is more likely to interfere with the edge of the locking hole  2   a  when the lock  4  is deformed. 
     The invention was completed based on the above problem and an object thereof is to improve a detaching operability of a terminal fitting while in particular allowing to secure a sufficient force to lock the terminal fitting. 
     SUMMARY OF THE INVENTION 
     The invention is directed to a connector with a housing that has at least one cavity and at least one terminal fitting that can be inserted into the cavity. A resiliently deformable lock is in the cavity and is contacted by the terminal fitting as the terminal fitting is inserted into the cavity. The contact by the terminal fitting causes the lock to deform in a deforming direction that intersects the inserting and withdrawing directions of the terminal fitting. The lock restores resiliently when the terminal fitting is inserted completely, and locks the terminal fitting in the cavity. The lock has a locking surface for engaging the terminal fitting. The locking surface comprises a deforming-direction front section at the front side relative to the deforming direction of the lock and a deforming-direction rear section at the backside relative to the deforming direction. An angle of the deforming-direction rear section to the withdrawing direction of the terminal fitting is smaller than an angle of the deforming-direction front section to the withdrawing direction. 
     Accordingly, the terminal fitting can be detached from the connector housing by forcibly deforming the lock away from the terminal fitting and pulling the terminal fitting back. The angle of the deforming-direction rear section to the withdrawing direction is smaller than the angle of the deforming-direction front section thereto. Thus, a trace of displacement of the locking surface during the resilient deformation of the lock is more backward as compared to a case where the locking surface has the same angle of inclination over the entire length. Thus, the lock is less likely to interfere with the terminal fitting during resilient deformation, and detachment of the terminal fitting is reliable. 
     The deforming-direction front section preferably is inclined at an obtuse angle to the withdrawing direction of the terminal fitting. 
     The terminal fitting inserted into the cavity of the connector housing is held so as not to come out by the lock. The deforming-direction front section of the locking surface of the lock is inclined at an obtuse angle to the withdrawing direction of the terminal fitting. Thus, even if a force acts to pull the terminal fitting back in its locked state, a component of the force acts on the lock in a direction opposite from the deforming direction, making it difficult to disengage the lock. Therefore, a force to lock the terminal fitting can be increased. 
     The angle of the deforming-direction rear section may be substantially normal to the inserting and withdrawing directions of the terminal fitting. 
     The terminal fitting may comprise a locking projection that engages the deforming-direction front section of the locking surface for locking. The deforming-direction front section preferably is inclined in the same direction as a locking section of the terminal fitting. 
     The lock preferably is supported at both ends. Thus, a high strength can be maintained even if the thickness is reduced as compared to conventional locks supported only at one end and. Accordingly, a force to lock the terminal fitting can be enhanced, and the connector suited to being miniaturized can be provided. 
     The housing preferably has a forward opening for forming the locking surface of the lock. A section of the lock that projects more forward than the locking surface is connected with at least one side surface of the opening. The connected section does not hinder the formation of the locking surface, and enables the locking surface to be wider. Thus, even if the connector is miniaturized, a sufficient locking force can be secured for the terminal fitting. Thus, the connector is suited to being miniaturized. 
     The section of the lock that projects more forward than the locking surface preferably is formed with a manoeuvrable groove that opens forward and is manoeuvrable by a disengagement jig to deform the lock. The disengagement jig preferably can be inserted into the opening for manoeuvring the manoeuvrable groove. Most preferably, jig-introducing groove forks or divides the section of the lock projecting more forward than the locking surface. 
    
    
     These and other objects, features and advantages of the present invention will become more apparent upon reading of the following detailed description of preferred embodiments and accompanying drawings. It should be understood that even though embodiments are separately described, single features thereof may be combined to additional embodiments. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view of a female housing according to one embodiment of the invention. 
     FIG. 2 is a rear view of the female housing. 
     FIG. 3 is a perspective view partly in section of the female housing. 
     FIG. 4 is a front view of a female terminal fitting. 
     FIG. 5 is a bottom view of the female terminal fitting. 
     FIG. 6 is a left side view of the female terminal fitting. 
     FIG. 7 is a cross sectional view of the female housing taken along  7 A— 7 A of FIG.  1  and of the female terminal fitting taken along  7 B— 7 B of FIG. 4 showing a state before the female terminal fitting is inserted into the female housing with a retainer mounted at a partial locking position. 
     FIG. 8 is a cross sectional of the female housing taken along line  8 A— 8 A of FIG.  1  and of the female terminal fitting taken along  8 B— 8 B of FIG. 4 showing the state before the female terminal fitting is inserted into the female housing with the retainer mounted at the partial locking position. 
     FIG. 9 is a cross sectional view of the female housing taken along line  9 — 9  of FIG.  1  and with the female terminal fitting is shown by a plan view in a state before the female terminal fitting is inserted into the female housing with the retainer mounted at the partial locking position. 
     FIG. 10 is a sectional view similar to FIG. 7 but showing an intermediate stage of insertion of the female terminal fitting into the female housing. 
     FIG. 11 is a sectional view similar to FIG. 7 but showing a state where the female terminal fitting is inserted in the female housing. 
     FIG. 12 is a section view similar to FIG. 8, but showing the state where the female terminal fitting is inserted in the female housing. 
     FIG. 13 is a sectional view similar to FIG. 9 showing the state where the female terminal fitting is inserted in the female housing. 
     FIG. 14 is a side view similar to FIG. 7, but showing a state where the retainer is moved to a full locking position. 
     FIG. 15 is a sectional view similar to FIG. 7, but showing a state where a disengagement jig is inserted in a maneuverable groove. 
     FIG. 16 is a sectional view similar to FIG. 7, but showing a state where a lock is resiliently deformed by the disengagement jig. 
     FIG. 17 is a section of a prior art connector. 
     FIG. 18 is a partial section showing improved prior art connector. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A female connector in accordance with the invention has female terminal fittings  10  mounted in a female housing  40 , as shown in FIGS. 1 to  16 . The female housing  40  is connectable with an unillustrated male housing so that the female terminal fittings  10  are electrically connectable with unillustrated male terminal fittings in the male housing. In the following description, directions of inserting and withdrawing the female terminal fittings  10  into and from the female housing  40  are referred to as forward and backward directions, respectively, and reference is made to FIG. 7 concerning the vertical direction. 
     The female terminal fitting  10  is formed by embossing, folding and/or bending a metallic material that has been stamped or cut into a specified shape. The female terminal fitting  10 , as shown in FIGS. 4 and 5, has a main body  11  substantially in the form of a box with open front and rear ends and a barrel  12  to be crimped, bent or folded into connection with an end of a wire W. The barrel  12  has a front pair of crimping pieces  12   a  for crimped connection with a core Wa of the wire W, and a rear pair of crimping pieces  12   b  for crimped connection with an insulated portion Wb of the wire W. 
     The main body  11  has a ceiling wall  13  that extends in forward and backward directions, left and right sidewalls  14 ,  15  that extend down from opposite lateral edges of the ceiling wall  13 , a bottom wall  16  that extends from the projecting end of the left sidewall  14  of FIG. 4 to face the ceiling wall  13 , and an outer wall  17  that extends from the projecting end of the right sidewall  14  of FIG. 4 to be placed below and outside the bottom wall  16 . 
     The front end of the ceiling wall  13  is retracted back as compared to the front ends of the other walls  14 ,  15 ,  16  and  17 , and a resilient contact piece  38  projects from this front end as shown in FIG.  7 . The resilient contact piece  18  is formed from a tongue that extends from the front end of the ceiling wall  13  and is folded to face the ceiling wall  13  and the bottom wall  16 . Thus, the resilient contact piece  18  is supported only at one end and has a substantially triangular shape. The resilient contact piece  18  can be brought resiliently into contact with a tab of a mating male terminal fitting inserted into the main body  11  from the front. A receiving portion  19  projects in from the bottom wall  16  substantially facing the resilient contact  18 . The receiving portion  19  can hold the tab while squeezing it in cooperation with the resilient contact piece  18 . An excessive deformation preventing projection  20  is embossed in the ceiling wall  13  and projects toward the resilient contact  18 . Engagement of the resilient contact piece  18  with the excessive deformation preventing projection  20  prevents deformation of the resilient contact piece  18  beyond its resiliency limit. 
     A cut-away portion  21  divides the outer wall  17  into front and rear portions  17   a  and  17   b , as shown in FIGS. 5 and 7. The cut-away  21  is formed over substantially the entire width of the outer wall and is substantially at its longitudinal middle. The front cut end surface  21   a  of the cut-away portion  21  is inclined up and to the back over its entire area. The cut-away portion  21  is slightly shorter than half the length of the outer wall  17  and extends up to the bottom end of the sidewall  15  at the upper side in FIG. 5. A bulging piece  22  extends from the projecting end of the bottom wall  16  and contacts the bottom end surface of the sidewall  15  to hold the bottom wall  16  substantially horizontally. The entire area of the bottom wall  16 , except a contact portion of the bulging piece  22  with the sidewall  15 , is slightly lower than this contact portion, thereby increasing a depth of engagement with the lock  13 . The front portion  17   a  of the outer wall  17  is slightly shorter than the rear portion  17   b  in forward and backward directions. 
     A rear-portion holding piece  46  is bent up from the projecting end of the rear portion  37   b  of the outer wall  37 , as shown in FIG. 6, and fits into a rear portion holding groove  48  to prevent loose forward and backward movement of the rear portion  37   b . A stabilizer  47  is bent down from the projecting end of the rear portion  37   b  of the outer wall  37  and fits in the stabilizer-inserting groove  20  to guide the insertion of the female terminal fitting  30  into the cavity  11 . The front end of the rear-portion holding piece  46  and the front end of the rear portion  37   b  are substantially aligned with each other. Similarly, the rear end of the stabilizer  47  and the rear end of the rear portion  37   b  are substantially aligned with each other. A projection  49  is embossed to project out at the widthwise center of the rear end of the rear portion  37   b  and has a length substantially equal to the length of the stabilizer  47 . 
     A locking projection  29  is embossed out from the front portion  17   a  of the outer wall  17  at a position displaced slightly to the left of center in FIG.  4  and adjacent the front cut end of the cut-away portion  21 . The locking projection  29 , as shown in FIGS. 5 and 6, is tapered so that the width and height of the locking projection  29  gradually decrease toward a vertex at the front end. More particularly, the locking projection  29  has a pyramid portion  29   a  formed by three slanted surfaces and a rectangular tube portion  29   b  with a substantially constant width and height and formed by three sequentially connected side surfaces. The pyramid portion  29   a  of the locking projection  29  is tapered and has a slightly rounded front end. The rectangular tube portion  29   b  of the locking projection  29  overhangs back substantially along the inclination of the front cut end surface  21   a  of the cut-away portion  21  and projects more back towards the cut-away portion  21  than the front portion  17   a  of the outer wall  17 . 
     The locking projection  29  projects up to substantially the same height as the projection  27 . The rear end of the locking projection  29  is formed by the front cut end surface  21   a  of the cut-away portion  21 , which inclines in and up to the back. The rear end surfaces of the front portion  17   a  of the outer wall  17  at opposite sides of the locking projection  29  also are formed by the inwardly and upwardly inclined front cut end surface  21   a.    
     A front-portion holding piece  30  is bent up from the projecting end of the front portion  17   a  of the outer wall  17  and fits into a front-portion holding groove  31  in the side wall  14 , as shown in FIG. 6, to prevent the front portion  17   a  from making loose forward and backward movements. The front-portion holding piece  30  projects more backward than the front portion  17   a  of the outer wall  17 . The cut-away portion  21  extends into the base end of the front-portion holding piece  30 , and the cut end surface  44   a  thereof is inclined in and up to the back as already described. 
     The female housing  40  is molded of a resin and cavities  41  are arranged substantially side-by-side at two stages in the female housing  40 , as shown in FIGS. 1,  2  and  7 . Each cavity  41  has a bottom wall  42 , and a lock  43  projects from the bottom wall  42  into each cavity  41 . Each lock  43  is configured to engage the female terminal fitting  10  that has been inserted into the cavity  41 . The female housing  40  also has a front wall  44  that defines a front-limit position for the terminal fittings  10  in the cavity  41 . The front wall  44  of the female housing  40  is formed with tab insertion holes  45  for receiving tabs of the mating male terminal fittings that are inserted into the cavities  41  from the front. Converging or tapered guide surfaces  46  are formed at the front edges of the tab insertion holes  45  over substantially the entire periphery, so that the tabs can be guided smoothly into the cavities  41 . 
     A projection-inserting groove  47  is formed substantially in the widthwise center of the bottom wall  42 , and a stabilizer-inserting groove  48  is formed at the right side of the projection-inserting groove  47  in FIG.  2 . The stabilizer-inserting groove  48  is deeper than the projection-inserting groove  47 , and both grooves have open rear ends. The projection-inserting groove  47  is dimensioned and disposed to receive the locking projection  29  and the projection  27  of the female terminal fitting  10  and the stabilizer-inserting groove  48  is dimensioned and disposed to receive the stabilizer  25 . The projection-inserting groove  47  is substantially continuous with the lock  43 , as described below, whereas the front end of the stabilizer-inserting groove  48  is slightly behind the lock  43 . 
     A projection  49  is provided at the front end of the upper surface of the cavity  41  and gradually projects down toward the lock  43  over the entire width of the cavity  41 . The projection  49  pushes the front end of the female terminal fitting  10  toward the lock  43  as the female terminal fitting  10  is inserted into the cavity  41 , and hence increases the depth of engagement with the lock  43 . The peripheral edge of the rear end of the cavity  41  is inclined in and to the front over substantially the entire periphery to guide the female terminal fitting  10 . A restriction  50  is at an upper-left position of the peripheral edge of the rear end of the cavity  41  in FIG.  2  and extends at an angle to the inserting and withdrawing directions IWD of the female terminal fitting  10 . The restriction  50  contacts the stabilizer  25  when the female terminal fitting  10  is inserted improperly into the cavity  41 , thereby hindering insertion. Further, opposite sidewalls of the cavity  11  bulge so that a substantially front half is narrower than a substantially rear half as shown in FIG.  9 . 
     A retainer mount hole  51  is formed in the bottom wall of the female housing  40 , as shown in FIG. 7, and receives a retainer  52  is mountable from below for doubly locking the female terminal fittings  10 . This retainer mount hole  51  laterally exposes longitudinal middle portions of the respective cavities  41  e.g. to outside below. The retainer  52  includes fastening portions  53  arrayed at two stages and substantially corresponding to the respective cavities  41 , and is vertically movable between two positions in the female housing  40 , namely, a partial locking or first position (see FIG. 7) where the respective fasteners  53  are retracted down from the corresponding cavities  41  to permit the insertion and withdrawal of the female terminal fittings  10  into and from the cavities  41 . The retainer  52  also can be moved to a full locking position (see FIG. 14) where the respective fasteners  53  enter the corresponding cavities  41  to lock the female terminal fittings  10 . The retainer  52  can be held selectively at the partial locking position and the full locking position by an unillustrated holder. 
     The lock  43  is at the front of the bottom wall  42  of the cavity  41  and has an arm  54  supported at both front and rear ends. A fastening projection  55  projects into the cavity  41  from the upper surface of the arm  54 , as shown in FIGS. 3 and 7. The fastening projection  55  can enter the cut-away portion  21  of the female terminal fitting  10  to engage the front cut end surface  21   a . The lock  43  is substantially transversely symmetrical when viewed from the front. 
     The arm  54  is slightly narrower than the cavity  41  (see FIG. 9) and has its opposite bottom ends chamfered (see FIG.  1 ). The arm  54  is resiliently deformable in a vertical deformation direction DD that intersects the inserting and withdrawing directions IWD of the female terminal fitting  10 . Front and rear ends define the supports about which the arm  54  deflects. Thus, the arm  54  has a substantially arch shape and a longitudinal middle portion of the arm  54  is at a bottommost position (see FIG. 10) during the deformation. A deformation permitting space is provided below the arm  54  to permit resilient deformation of the arm  54 , and excessive deformation preventing rails  56  are spaced below the opposite chamfered sides of the arm  54  by the height of the deformation permitting space. The excessive deformation preventing rails  56  have a substantially triangular cross section extend along the longitudinal direction of the lock  43 . The excessive deformation preventing rails  56  prevent excessive resilient deformation of the lock  43  by engaging the lock  43  before the lock  43  is deformed beyond its resiliency limit. A rear portion  54   b  of the arm  54  is connected with the bottom wall  42  over substantially the entire width and is sloped up toward the front, whereas a front portion  54   a  thereof is connected partly with the front wall  44  of the female housing  40  and is substantially horizontal. The projection-inserting groove  47  in the bottom wall  42  is formed continuously in the rear portion  54   b , and parts of the rear portion  54   b  left at the opposite sides of the projection-inserting groove  47  serve as rear supports  57  for supporting the female terminal fitting  10  from below. 
     The fastening projection  55  is as wide as the arm  54  (see FIG.  9 ). The front end of the fastening projection  55  substantially aligns with the front end of the rear portion  54   b  of the arm  54 , and the rear surface the fastening projection  55  is inclined to be continuous with the rear portion  54   b . The projection-inserting groove  47  in the rear portion  54   b  of the arm  54  is formed continuously in the fastening projection  55 . Thus, the widthwise middle of the fastening projection  55  is recessed when viewed from the front (see FIG.  1 ). The front surface of the fastening projection  55  defines an upper locking surface  58  that is engageable with portions of the front cut end surface  21   a  of the cut-away portion  21  of the female terminal fitting  10  at the opposite sides of the locking projection  29  (see FIG.  12 ). The upper locking surface  58  is substantially normal to forward and backward directions. 
     A forwardly open maneuverable groove  59  is formed in the widthwise center of the upper surface of the front portion  54   a  of the arm  54  and extends over substantially the entire length of the front portion  54   a . The maneuverable groove  59  is configured to receive a disengagement jig J from the front (see FIG. 15) for forcibly deforming the lock  43 . Parts of the front portion  54   b  at the opposite sides of the maneuverable groove  59  define front supports  60  for supporting the female terminal fitting  10  from below. Thus, the maneuverable groove  59  makes the front portion  54   a  of the arm  54  thinner than the rear portion  54   b . The maneuverable groove  59  has a depth slightly over half the thickness of the front portion  54   a  of the arm  54 , and opposite side surfaces of the maneuverable groove  59  curve up to opposite outer sides to conform substantially to the outer shape of the arm  54  (see FIG.  1 ). The locking projection  29  of the female terminal fitting  10  inserted into the cavity  41  enters this maneuverable groove  59 . A lower locking surface  61  is formed at the rear end of the maneuverable groove  59  and is substantially continuous with the upper locking surface  58 . The lower locking surface  61  is engageable with the rear end of the locking projection  29  of the front cut end surface  21   a  of the cut-away portion  21  of the female terminal fitting  10 . This lower locking surface  61  is inclined more backward than the upper locking surface  58 . 
     A jig-introducing groove  62  splits the front half of the front portion  54   a  of the arm  54  and communicates with the maneuverable groove  59  for receiving the disengagement jig J. An upwardly and rearwardly inclined guide surface  63  is formed at the rear end of the jig-introducing groove  62  for guiding the disengagement jig J into the maneuverable groove  59 . 
     A locking surface  64  of the lock  43  for engaging with the female terminal fitting  10  is comprised of the upper and lower locking surfaces  58  and  61 , as shown in FIG.  7 . The upper locking surface  58  is formed by the front surface of the fastening projection  55 , which is the portion of the fastening projection  55  that projects further into the cavity  41 . The lower locking surface  61  is formed by the back surface of the maneuverable groove  59 . The upper and lower locking surfaces  58 ,  61  are discontinuous and are aligned at different angles α, β to the withdrawing direction WD of the female terminal fitting  10 . Specifically, the angle α between the lower locking surface  61  and the withdrawing direction WD of the female terminal fitting  10  is 90° or larger, i.e. an obtuse angle. However, the angle β between the upper locking surface  58  and the withdrawing direction preferably is about 90°. Accordingly, the angle β of the upper locking surface  58  to the withdrawing direction WD is smaller than the angle α of the lower locking surface  61 . The angle α of the lower locking surface  61  to the withdrawing direction WD of the female terminal fitting  10  preferably is about the same as an angle of the front cut end surface  21   a  of the cut-away portion  21  of the female terminal fitting  10  thereto. 
     The connector of the invention is used by first mounting the retainer  52  in the partial locking position in the female housing  40 , as shown in FIGS. 7 to  9 . The female terminal fitting  10  then is inserted into the cavity  41  from behind with the barrel  12  of the female terminal fitting  10  crimped, bent or folded into connection with the wire W. If an attempt is made to insert the female terminal fitting  10  upside down, the front end surface of the upward-facing stabilizer  25  contacts the restricting portion  50  at the rear end of the cavity  41 , thereby hindering insertion of the female terminal fitting  10 . In this way, an upside-down insertion of the female terminal fitting  10  is prevented. 
     Insertion of the properly oriented female terminal fitting  10  into the cavity  41  moves the locking projection  29  into the projection-inserting groove  47 . The projection  27  and the stabilizer  25  then enter the projection-inserting groove  47  and the stabilizer-inserting groove  48 , respectively so that the female terminal fitting  10  can be inserted smoothly while being prevented from shaking along vertical and transverse directions. When the female terminal fitting  10  is inserted to a specified depth, the lock  43  is pressed by the locking projection  29 , and the arm  54  is deformed down in the deformation direction DD and into a shallow V-shape when viewed sideways. Thus, the front portion  54   a  is inclined backward while the rear portion  54   b  is inclined forward. The locking projection  29  is substantially pyramidal and has a vertex at the front end. Thus, the locking projection  29  can be inserted smoothly along the projection-inserting groove  47  and can smoothly press the lock  43 . 
     There are cases where an operator tries to move the retainer  52  to the full locking position before the female terminal fitting  10  has reached a proper depth. In such a case, the fastening portion  53  of the retainer  52  contacts the bottom surface of the main body  11  of the female terminal fitting  10  to prevent the retainer  52  from moving to the full locking position. Thus, the insufficient insertion of the female terminal fitting  10  can be detected. 
     The locking projection  29  moves beyond the fastening projection  55  and enters the maneuverable groove  59  when the female terminal fitting  10  is inserted to the proper depth in the cavity  41 , as shown in FIGS. 11 to  13 , whereupon the lock  43  is restored resiliently. The fastening projection  55  of the lock  43  then enters the cut-away portion  21 , the lower locking surface  61  engages the rear edge of the locking projection  29  of the front cut end surface  21   a  of the cut-away portion  21  (see FIG.  11 ), and the upper locking surface  58  engage the portions of the front cut end surface  21   a  of the cut-away portion  21  at the opposite sides of the locking projection  29  (see FIG.  12 ). In this way, the female terminal fitting  10  is held by the lock  43  so as not to come out. In the process of properly inserting the female terminal fitting  10 , a depth of engagement of the lock  43  with the female terminal fitting  10  is increased since the front end of the main body  11  is pushed down toward the lock  43  by the jutting portion  49  on the ceiling surface of the cavity  41 . 
     The upper locking surface  58  of the lock  43  defines the maximum width of the lock  43 , and the front cut end surface  21   a  of the cut-away portion  21  of the female terminal fitting  10  extends over the entire width of the female terminal fitting  10 . Thus, the female terminal fitting  10  is held in the cavity  41  by a strong locking force. Further, the front cut end surface  21   a  of the cut-away portion  21  and the lower locking surface  61  both are inclined at obtuse angles to the withdrawing direction of the female terminal fitting  10 . Thus, even if a force on the wire W acts to pull the locked female terminal fitting  10  back, a component of force acts on the lock  43  in an obliquely upward direction to the back, which is substantially opposite the downward deforming direction DD. Thus, it is difficult to disengage the lock  43 , and a force to lock the terminal fitting  10  is made even stronger. 
     The retainer  52  is moved to the full locking position, as shown in FIG. 14, after all the female terminal fittings  10  are inserted properly into the corresponding cavities  41 , and the fastening portions  53  enter the corresponding cavities  41  to engage the stepped portions  28  including the projections  27 . In this way, the female terminal fittings  10  are locked doubly in the cavities  41  by the locks  43  and the retainer  52 . 
     The terminal fitting  10  may have to be withdrawn from the female housing  40  for maintenance or other reason. In such a case, the retainer  52  is returned from the full locking position to the partial locking position, as shown in FIG.  11 . The lock  43  then is deformed by inserting the disengagement jig J into the jig-introducing groove  62  and the maneuverable groove  59 . An initial inserting operation can be performed easily since a wide entrance for the disengagement jig J is provided by the jig-introducing groove  62 . Further, the back surface of the jig-introducing groove  62  is formed into the guide surface  63 , which is inclined toward the maneuverable groove  59 . Thus, the disengagement jig J can be guided smoothly to the maneuverable groove  59 . 
     The disengagement jig J is inserted to the back of the maneuverable groove  59  and moved along the inclination of the outer surface of the locking projection  29 , as shown in FIG.  15 . Thus, the leading end of the disengagement jig J pushes the wall surface of the maneuverable groove  59  down to deform the arm  54 , as shown in FIG.  16 . The wire W is gripped and pulled back in the withdrawal direction WD when the lock  43  is deformed away from the female terminal fitting  10 , and the female terminal fitting  10  can be pulled out of the cavity  41 . 
     The angle α of the upper locking surface  58  of the locking surface  64  to the withdrawing direction of the female terminal fitting  10  is smaller than the angle β of the lower locking surface  61  thereto. Therefore, a trace of displacement of the locking surface  64  during the deformation of the lock  43  is further back than a locking surface that has the same angle of inclination over the entire length, as shown by phantom line in FIGS. 15 and 16. Thus, the locking surface  64  is less likely to interfere with the locking projection  29  during the deformation of the locking surface  64 . Even if the locking surface  64  should interfere with the locking projection  29 , it is caught more lightly than the one shown by phantom line. Therefore, the lock  43  can be deformed and the interference is overcome easily by slightly pushing the female terminal fitting forward via the wire W. 
     That the trace of displacement of the locking surface  64  during the deformation of the lock  43  is further back means a smaller clearance between the locking surface  64  of the lock  43  and the front cut end surface  21   a  of the cut-away portion  21  of the female terminal fitting  10  when the female terminal fitting  10  is inserted to a proper depth in the cavity  41  (see FIG.  11 ). Thus, a range within which the female terminal fitting  10  may shake forward and backward while being properly inserted in the cavity  41  becomes smaller. This reduces the possibility of making the electrical connection between the female terminal fitting  10  and the mating terminal fitting unstable. 
     As described above, the lower locking surface  61  is inclined at an obtuse angle to the withdrawing direction WD of the female terminal fitting  10 . Thus, even if a force acts to pull the locked terminal fitting  10  back, a component of force acts on the lock  43  in a direction substantially opposite the deforming direction DD, making it difficult to disengage the lock  43 . As a result, a force to lock the terminal fitting  10  can be increased. On the other hand, the angle β of the upper locking surface  58  with respect to the withdrawing direction WD of the terminal fitting  10  is smaller than the angle α of the lower locking surface  61  thereto. Thus, the trace of displacement of the locking surface  64  during deformation of the lock  43  can be more backward as compared to a locking surface having the same angle of inclination over the entire length. Thus, the lock  43  is less likely to interfere with the terminal fitting  10  during the deformation of the lock  43  at the time of detaching the terminal fitting  10 , and the terminal fitting  10  can be detached more reliably. Therefore, a large locking force can be secured for the female terminal fitting  10  even if the strength of the lock  43  is lowered as a result of miniaturization and the detaching operability of the female terminal fitting  10  can be improved. 
     The invention is not limited to the above described and illustrated embodiment. For example, the following embodiments are also embraced by the technical scope of the present invention as defined by the claims. Beside the following embodiments, various changes can be made without departing from the scope and spirit of the present invention as defined by the claims. 
     Although the angle of the upper locking surface to the withdrawing direction of the female terminal fitting is about 90° in the foregoing embodiment, it may be larger than or smaller than 90° provided that this angle is smaller than the angle of the lower locking surface to the withdrawing direction WD. 
     The upper locking surface is on the fastening projection and the lower locking surface is on the arm in the foregoing embodiment. However, both upper and lower locking surfaces may be provided on the fastening projection. 
     Although a lock supported at both ends is described above, the invention is also applicable to locks supported only at one end. 
     The female terminal fitting has the locking projection in the foregoing embodiments. However, connectors in which female terminal fittings having no locking projection also are embraced by the present invention. 
     Although the female connector in which the female terminal fittings are accommodated in the female housing is described in the foregoing embodiment, the present invention is also applicable to male connectors in which male terminal fittings are accommodated in a male housing.