Patent Publication Number: US-8974256-B2

Title: Terminal fitting and production method therefor

Description:
BACKGROUND 
     1. Field of the Invention 
     The invention relates to a female terminal fitting and to a production method therefor. 
     2. Description of the Related Art 
     U.S. Pat. No. 6,520,811 discloses a female terminal fitting including a resilient contact piece in a rectangular tube. A tab of a mating terminal inserted into the rectangular tube is resiliently sandwiched between the resilient contact piece and a receiving plate of the rectangular tube. The rectangular tube includes a supporting plate supporting the resilient contact piece. First and second side plates extend substantially at a right angle from left and right side edges of the supporting plate. The receiving plate extends substantially at a right angle from the extending end edge of the first side plate and an outer plate extends substantially at a right angle from the extending end edge of the second side plate and is placed on the outer surface of the receiving plate. 
     A part of the outer plate is cut to form a cut portion, and an opening edge of the cut portion is struck to project outwardly by the plate thickness of the outer plate, thereby forming a locking projection. When the terminal fitting is inserted into a terminal accommodating chamber of a housing, a locking lance formed to extend along the inner wall of the terminal accommodating chamber enters the cut portion to be engaged with the locking projection for retaining the terminal fitting. 
     In the terminal fitting of U.S. Pat. No. 6,520,811, the sum of a dimension corresponding to the plate thickness of the outer plate obtained by forming the cut portion in the outer plate and a dimension corresponding to the plate thickness of the outer plate obtained by forming the locking projection by striking is ensured as an engagement margin with the locking lance. However, since the engagement margin by the locking projection out of this engagement margin corresponding to twice the plate thickness of the outer plate portion is obtained as a projection from the outer surface of the rectangular tube, the terminal fitting becomes bulky in a resilient deforming direction of the resilient contact piece. 
     The present invention was developed in view of the above situation and an object thereof is to improve the design of the terminal fitting. 
     SUMMARY OF THE INVENTION 
     The invention relates to a terminal fitting, comprising a tube and a resilient contact piece in the tube. The tube also has a receiving plate configured to resiliently sandwich a tab of a mating terminal inserted into the tube between the receiving plate and the resilient contact piece. First and second side plates extend from the receiving plate. A supporting plate extends at an angle, preferably substantially at a right angle from a front area of the extending end of the first side plate and is connected to a base end part of the resilient contact piece. An outer plate extends at an angle, preferably substantially at a right angle, from a front end area of the extending end of the second side plate and is at least partly placed on the outer surface of the supporting plate. A first ceiling plate extends at an angle, preferably substantially at a right angle, from a rear end area of the extending end edge of the first side plate arranged at an inner side of the supporting plate. A second ceiling plate extends at an angle, preferably substantially at a right angle, from a rear end area of the extending end edge of the second side plate arranged at an inner side of the supporting plate and at least partly placed on the first ceiling plate. At least one retainer functioning portion is formed on the rear end of at least one of the supporting plate and the outer plate and is locked by a locking lance of a terminal accommodating chamber. The design of the terminal fitting is improved by reducing the height of the tube. 
     According to the above configuration, the sum of a dimension corresponding to the plate thickness of the supporting plate and that corresponding to the plate thickness of the outer plate is at least ensured as an engagement margin with a locking lance. If an area between the outer surface of the receiving plate and the outer surface of the supporting plate is a reference range concerning a height direction of the tube, only a part of the engagement margin with the locking lance corresponding to the plate thickness of the outer plate projects out from the reference range. Thus, the height of the present invention is reduced as compared with the case where the entire engagement margin with the locking lance is ensured in an area outside the reference range. 
     The resilient contact piece may be folded back from the front end of the supporting plate and substantially extends in a cantilever manner. An auxiliary spring piece may extend from one of the first and second ceiling plates and supports a rear end part of the resilient contact piece. According to this configuration, a contact pressure between the resilient contact piece and the tab is increased by supporting the rear end part of the resilient contact piece by the auxiliary spring piece. 
     A displacement of the ceiling plate located on an inner side may be restricted by engaging the extending end edge of the inner ceiling plate with the side plate, and the auxiliary spring piece may be formed on the ceiling plate located on the inner side. According to this configuration, the ceiling plate formed with the auxiliary spring piece engages the side plate and will not displace in an escaping direction when receiving a resilient force from the resilient contact piece. Thus, the reliability of a function of increasing the contact pressure by the auxiliary spring piece is excellent. 
     The auxiliary spring piece may be formed on the ceiling plate located on an inner side and the ceiling located on an outer side may cover at least a part of the auxiliary spring piece from an outer side. Thus, the ceiling plate located on the outer side protects the auxiliary spring piece from interference by external matter. 
     The invention also relates to a terminal fitting with a tube at or near a front part and a wire connection portion at or near a rear end part. A coupling links the rear end of the tube and the front end of the wire connection portion. A base plate extends continuously over the tube, the coupling and the wire connection portion. Two side plates of the tube project at an angle, preferably substantially at a right angle, from the base plate. One or more coupling plates of the coupling extend at an angle, preferably substantially at a right angle, from the base plate and have front ends and the rear ends thereof connected to the side plates and portions of the wire connection portion. At least one reinforcement is formed by striking an area of the base plate of the coupling outwardly. Accordingly, the design of the terminal fitting is improved by stabilizing the shape of a tube while improving material yield. Additionally, the design of the terminal fitting is improved by increasing the strength of a coupling between the tube and the wire connection portion. 
     The wire connection portion preferably comprises a wire crimping portion having two crimping pieces extending from the opposite widthwise side edges of the base plate. The front ends and the rear ends of the coupling plates preferably are connected to the side plates and the crimping pieces. 
     A formation area of the reinforcement in a width direction may be only a part of the base or bottom plate in the width direction. 
     The reinforcement is designed to interfere with an opening edge at the entrance of a terminal accommodating chamber during an attempt to insert the terminal fitting into the terminal accommodating chamber in an improper posture. Thus, the reinforcement can function as a stabilizer for preventing the insertion of the terminal fitting in an improper posture. 
     The reinforcement may continuously extend from the coupling to an area of the bottom plate forming the rectangular tube. Accordingly strength at a boundary between the rear end of the tube and the front end of the coupling is increased. 
     The outer surface of a connection area of the base plate of the wire connection portion may be located more outwardly than the outer surface of an area of the coupling where the reinforcement is not formed. Thus, at least a part of the reinforcement is accommodated in a dead space formed due to a height difference between the outer surface of the connection area and that of the area of the coupling where the reinforcement is not formed. Thus, the connection area substantially prevents external matter from interfering with the reinforcement. 
     The reinforcement increases the strength of the coupling. 
     The invention also relates to a terminal fitting with a tube and a base plate forming part of the tube. Side plates extending at an angle and preferably at substantially a right angle from the base plate and two ceiling plates extend at angles and preferably at substantially right angles from the side plates. The ceiling plates are arranged in parallel facing relationship. At least one projection is formed by causing one of the ceiling plates to project and contact the other ceiling plate. 
     If an elevation dimension of the side plate connected to the inner ceiling plate is reduced to improve material yield, a clearance between the pair of ceiling plate portions is widened. However, the projection formed on the one ceiling plate contacts the other ceiling plate to stabilize the shape of the tube while improving material yield. 
     A contact area of the projection with the other ceiling plate may be a substantially flat. This surface contact makes the ceiling plates unlikely to incline relative to each other and the shape of the tube is stabilized more. 
     A front plate of the ceiling is in a front end area of the tube and a rear plate of the ceiling may is behind the front plate and at a lower height than the front plate. A lock is formed on the rear end of the front plate for engagement with a locking lance on an inner wall of a terminal accommodating chamber to retain the tube in the terminal accommodating chamber. A resilient contact piece is folded back from the front of the front plate and is cantilevered into tube. An auxiliary spring piece is cantilevered forward from the rear plate and supports the resilient contact piece from the side of the locking lance at a support on or near the extending end thereof. A bend is formed on the auxiliary spring piece to bring an area behind the support closer to the locking lance. 
     The lock is formed utilizing a height difference between the front and rear plates. If the rear plate is displaced away from the locking lance to increase an engagement margin of the locking lance with the lock, the auxiliary spring piece also is displaced to a position more distant from the locking lance. Hence, the support of the auxiliary spring piece would be at a side of the resilient contact piece opposite to the locking lance and a supporting function by the auxiliary spring piece may be lost. However, the bend approaches the locking lance in an area of the auxiliary spring piece behind the support for the resilient contact piece. Thus, the support is displaced more toward the locking lance than if the bend was not formed. Therefore, the support properly supports the resilient contact piece from the side of the locking lance. 
     These and other objects, features and advantages of the invention will become more apparent upon reading of the following detailed description of preferred embodiments and accompanying drawings. Even though embodiments are described separately, single features thereof may be combined to additional embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of a terminal fitting of one embodiment. 
         FIG. 2  is a section along A-A of  FIG. 1 . 
         FIG. 3  is a section along B-B of  FIG. 2 . 
         FIG. 4  is a section along C-C of  FIG. 2 . 
         FIG. 5  is a side view. 
         FIG. 6  is a plan view. 
         FIG. 7  is a section showing a state where the terminal fitting is inserted into a terminal accommodating chamber and retained by a locking lance. 
         FIG. 8  is a development. 
         FIG. 9  is a front view of a terminal fitting according to a second embodiment. 
         FIG. 10  is a side view of the terminal fitting. 
         FIG. 11  is a bottom view of the terminal fitting. 
         FIG. 12  is a section along A-A of  FIG. 9 . 
         FIG. 13  is a section along B-B of  FIG. 10 . 
         FIG. 14  is a section along C-C of  FIG. 10 . 
         FIG. 15  is a front view of a terminal fitting of a third embodiment. 
         FIG. 16  is a side view of the terminal fitting. 
         FIG. 17  is a plan view of the terminal fitting. 
         FIG. 18  is a section along A-A of  FIG. 15 . 
         FIG. 19  is a partial enlarged view of  FIG. 18 . 
         FIG. 20  is a section along B-B of  FIG. 18 . 
         FIG. 21  is a section along C-C of  FIG. 18 . 
         FIG. 22  is a development of the terminal fitting. 
         FIG. 23  is a section of a terminal fitting of a fourth embodiment. 
         FIG. 24  is a section along D-D of  FIG. 23 . 
         FIG. 25  is a development of the terminal fitting. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A first embodiment of the invention is described with reference to  FIGS. 1 to 8 . A terminal fitting  10  of this embodiment is formed by bending, folding and/or embossing a conductive metal plate material  11  having a given thickness. The plate material  11  is punched or cut out into a shape shown in  FIG. 8  and is long and narrow in forward and backward directions, as shown in  FIGS. 2 ,  5  and  6 . Note that left side of  FIGS. 2 ,  5  to  7  is referred to as front concerning forward and backward directions in the following description. As shown in  FIGS. 2 ,  5  and  6 , a substantially rectangular tube  12  is formed on a front part of the terminal fitting  10  and a wire crimping portion  13  in the form of an open barrel to be connected to a wire (not shown) is formed on a rear end part of the terminal fitting  10 . The rear end of the tube  12  and the front end of the wire crimping portion  13  are linked via a coupling  14  having a substantially U-shaped cross-section. 
     As shown in  FIG. 7 , a tab  34  of a mating terminal  33  is to be inserted into the tube  12  from the front. As shown in  FIGS. 1 to 6  and  8 , the rectangular tube  12  includes a receiving plate  15 , a first side plate  16 , a second side plate  17 , a supporting plate  18 , an outer plate  20 , a resilient contact piece  23 , a first ceiling plate  25 , a second ceiling plate  27  and an auxiliary spring piece  29 . 
     The receiving plate  15  is a rectangle that is long and narrow in forward and backward directions. The first side plate  16  is long and narrow in forward and backward directions and projects at a substantially right angle from the left side of the receiving plate  15  in substantially an entire area in forward and backward directions. The projecting distance of the first side plate  16  from the receiving plate  15  is higher on a front part and a rear part is lowered to form a step or transitional inclined area. The second side plate  17  is long and narrow in forward and backward directions and projects at a substantially at a right angle from the right side of the receiving plate  15  in an entire area in forward and backward directions. The projecting distance of the second side plate  17  from the receiving plate  15  is higher in a front part and a rear part (a substantially rear half area) is lower to form a step or a transitional inclined area. 
     The supporting plate  18  extends at a substantially right angle from the elevated front area of the upper end of the first side plate  16 , substantially in parallel to the receiving plate  15 . At least one front locking projection  19  is formed on the right side opposite to the first side plate  16  of the supporting plate  18 . 
     The outer plate  20  extends at a substantially right angle from the elevated front area of the upper end of the second side plate  17  and is substantially parallel to the receiving plate  15  on the outer surface of the supporting plate  18 . The front end of the outer plate  20  is at substantially the same position as the front end of the second side plate  17  and that of the receiving plate  15 . The rear end of the outer plate  20  is behind the rear end of the supporting plate  18  in forward and backward directions. The rear end edge of the outer plate  20  is a retainer edge  21  for locking a locking lance  32  to be described later. 
     A front locking hole  22  is formed at a corner where the upper end of the second side plate  17  and the right end of the outer plate  20  meet at a substantially right angle. The front locking projection  19  is inserted and locked in the front locking hole  22 . This locking action restricts displacements of the supporting plate  18 , the second side plate  17  and the outer plate  20  in forward and backward directions and the vertical direction. Forward and backward directions mean directions parallel to an inserting direction of the tab  34  into the tube  12 . Further, the vertical direction means a direction in which the tab  34  is sandwiched between the resilient contact piece  23  and the receiving plate  15 , i.e. a direction in which the resilient contact piece  23  is resiliently deformed. 
     A base end part of the resilient contact piece  23  is connected to the front end of the supporting plate  18 . The resilient contact piece  23  is folded to cantilever obliquely down or in to the back from the front end of the supporting plate  18  and is resiliently deformable in the vertical direction with a fold  24  formed on the base end part as a support. A clearance between the receiving plate  15  and the resilient contact piece  23  in the vertical direction (deformation direction) is narrowed gradually from the front end to the rear end and is narrowest at a rear end of the resilient contact piece  23 . A shortest distance between the receiving plate  15  and the resilient contact piece  23  is shorter than the thickness of the tab  34  to be described later. 
     The front end of the folded portion  24  of the resilient contact piece  23  is behind the front end edge of the outer plate  20 . The rear end of the resilient contact piece  23  in a state not resiliently deformed is located behind the rear end of the supporting plate  18  and at substantially the same position as or slightly before the rear end of the outer plate  20  in forward and backward directions. Further, the rear end of the resilient contact piece  23  in the state not resiliently deformed is below or on the inner side of the supporting plate  18  in the vertical direction. Thus, the resilient contact piece  23  is accommodated entirely in the rectangular tube  12 . 
     The first ceiling plate  25  extends at a substantially right angle from the lowered rear end part of the upper end of the first side plate  16  and is substantially parallel to the receiving plate  15 . The height of the upper surface of the first ceiling plate  25  from the receiving plate  15  is lower than the lower surface of the supporting plate  18 . At least one rear locking projection  26  is formed on the right side edge of the first ceiling plate  25 . 
     The second ceiling plate  27  extends at a substantially right angle from the lowered rear area of the upper end of the second side plate  17 , is substantially parallel to the receiving plate  15  and is placed on the outer surface of the first ceiling plate  25 . The height of the upper surface of the second ceiling plate  27  from the receiving plate  15  is lower than the lower surface of the supporting plate  18 . The front end edge of the second ceiling plate  27  is behind the retainer edge  21  on the rear end of the outer plate  20  and before the front end of the first ceiling plate  25  in forward and backward directions. 
     A rear locking hole  28  is formed at a position near the upper end of the second side plate  17 . The rear locking projection  26  is inserted and locked in the respective rear locking hole  28 . Thus, the first ceiling plate  25 , the second side plate  17  and the second ceiling plate  27  are positioned in a state where relative displacements in forward and backward directions and vertical direction are restricted. 
     The auxiliary spring piece  29  is cantilevered forward from the front end of the first ceiling plate  25  and is resiliently deformable in the vertical direction (the same deformation direction of the resilient contact piece  23 ) with a rear end as a support. Although the auxiliary spring piece  29  is substantially parallel to the receiving plate  15 , it is bent to form a step at an intermediate position in an extending direction of the auxiliary spring piece  29  (forward and backward directions). Thus a rear end area of the auxiliary spring piece  29  slightly higher than a front end area thereof. 
     The front edge of the auxiliary spring piece  29  is located before the front end of the second ceiling plate  27  and the retainer edge  21  in forward and backward directions. Accordingly, a central part of the auxiliary spring piece  29  in forward and backward directions, excluding front and rear ends, is exposed outward between the outer plate  20  and the second ceiling plate  27 . The front end of the auxiliary spring piece  29  is placed on the upper surface of the rear part of the resilient contact piece  23 . Thus, the auxiliary spring piece  29  is entirely in the rectangular tube  12 . When the resilient contact piece  23  is not in contact with the tab  34  and not receiving a pressing force from the tab  34 , the resilient contact piece  23  and the auxiliary spring piece  29  may be in a contact state or a non-contact state facing each other from a short distance. If the resilient contact piece  23  and the auxiliary spring piece  29  are in contact, at least one of the resilient contact piece  23  and the auxiliary spring piece  29  is deformed resiliently. 
     As shown in  FIG. 7 , the terminal fitting  10  is inserted from behind into a terminal accommodating chamber  31  in a housing  30  made e.g. of synthetic resin. The locking lance  32  is cantilevered forward along an upper wall portion in the terminal accommodating chamber  31 . The outer surface of the outer plate  20  pushes the locking lance  32  in the process of inserting the terminal fitting  10  into the terminal accommodating chamber  31  and deforms the locking lance  32  resiliently up and out. The locking lance  32  resiliently restores and engages the retainer edge  21  from behind when the terminal fitting  10  reaches a proper insertion position in the terminal accommodating chamber  31 , thereby holding and retaining the terminal fitting  10 . 
     The tab  34  of the mating terminal  33  is inserted into the terminal accommodating chamber  31  from the front end of the housing  30  while the inserted terminal fitting  10  is retained by the locking lance  32 . Thus, the tab  34  enters the tube  12  and moves between the resilient contact piece  23  and the receiving plate portion  15 . The resilient contact piece  23  and the auxiliary spring piece  29  are deformed resiliently up and away from the receiving plate portion  15  at this time. Thus, the tab  34  is sandwiched resiliently between the receiving plate  15  and the resilient contact piece  23  by resilient restoring forces of the resilient contact piece  23  and the auxiliary spring piece  29 . In this way, a specified contact pressure on the tab  34  is ensured between the resilient contact piece  23  and the receiving plate  15 . Further, the contact pressure is increased by the resilient restoring force of the auxiliary spring piece  29 . 
     As shown in  FIG. 2 , the wall of the tube  12  vertically opposite to the receiving plate  15  has a double plate structure. The tab  34  slides in contact with the receiving plate  15 , and hence the receiving plate  15  cannot be formed with a step or a hole. However, it is possible to form a step or a hole on the supporting plate  18  supporting the resilient contact piece  23  or on the outer plate  20  to be placed on the outer surface of the supporting plate  18 . Thus, the wall opposite the receiving plate  15  has the at least double plate structure and has an elevation difference while forming a step over substantially the entire width of the rectangular tube  12 . Thus, a dimension corresponding to at least twice the plate thickness, i.e. the sum of a dimension Ta corresponding to the plate thickness of the supporting plate  18  and a dimension Tb corresponding to the plate thickness of the outer plate  20  is ensured as an engagement margin M with the locking lance  32 . This engagement margin M is ensured over the entire width of the rectangular tube  12 . 
     As described above, the engagement margin M corresponding to at least twice the plate thickness is ensured at the side opposite to the receiving plate  15 . However, if it is tried to ensure a dimension corresponding to twice or more the plate thickness as the engagement margin M with the locking lance  32  on the receiving plate portion side contrary to this embodiment, another plate is placed on the outer surface of the receiving plate and a struck portion is formed on that placed plate portion since the receiving plate portion cannot be formed with a step or a hole as described above. The height of a tube portion having such a shape and that of the tube  12  of this embodiment are compared. 
     If an area between the outer or lower surface of the receiving plate  15  and the outer or upper surface of the supporting plate  18  is a reference range H concerning the height direction HD of the rectangular tube  12 , only a part of the engagement margin M with the locking lance  32  corresponding to the plate thickness Tb of the outer plate  20  projects out from the reference range H in the terminal fitting  10 . Contrary to this, if it is tried to ensure the engagement margin M corresponding to twice the plate thickness on the receiving plate side, the engagement margin M is ensured in an area outside the reference range H. Thus, the height of the terminal fitting  10  of the present embodiment is reduced as compared with the case where the engagement margin M corresponding to twice the plate thickness is ensured on the receiving plate side. 
     Further, in the terminal fitting  10  of this embodiment, the displacement of the first ceiling plate  25  located on the inner side is restricted by the engagement of the rear locking projection  26  on the extending end of the first ceiling plate  25  with the rear locking hole  28  of the second side plate  17 , and the auxiliary spring piece  29  is formed on the first ceiling plate  25 , the displacement of which is restricted. According to this configuration, the first ceiling plate  25  is not displaced up away from the resilient contact piece  23  even if a resilient force from the resilient contact piece  23  acts on the first ceiling plate  25  via the auxiliary spring piece  29 . Thus, the reliability of a function of increasing a contact pressure by the auxiliary spring piece  29  is excellent. 
     Further, the auxiliary spring piece  29  is formed on the first ceiling plate  25  located on the inner side and the second ceiling plate  27  located on the outer side covers a part of the auxiliary spring piece  29  from the outer side. Accordingly, the second ceiling plate  27  protects the auxiliary spring piece  29  from interference from external matter. 
     The invention is not limited to the above described embodiment. For example, the following embodiments also are included in the scope of the invention. 
     The second ceiling plate extending from the same side plate as the outer plate is placed on the outer surface of the first ceiling plate extending from the same side plate as the supporting plate in the above embodiment. However, the ceiling plate extending from the same side plate as the outer plate may be placed on the inner side of the ceiling plate extending from the same side plate as the supporting plate. 
     The retainer edge is formed only on the rear end of the outer plate in the above embodiment. However, it may be formed only on the rear end edge of the supporting plate or on both the rear ends of the outer plate and the supporting plate. 
     The auxiliary spring piece is formed on the first ceiling plate, which is on the inner side in the above embodiment. However, it may be formed on the second ceiling plate, which is on the outer side. 
     Although the auxiliary spring piece is formed on the ceiling plate in the above embodiment, it may not be formed on the ceiling plate. 
     Although the second ceiling plate covers only a part of the auxiliary spring piece in the above embodiment, it may cover the entire auxiliary spring piece. 
     A second embodiment of the invention is described with reference to  FIGS. 9 to 14 . A terminal fitting  110  of this embodiment is long and narrow in forward and backward directions and is formed by bending, folding, embossing, striking, hammering and/or stamping a conductive metal plate material (not shown) punched or cut out into a specified shape. As shown in  FIGS. 10 to 12 , the terminal fitting  110  is formed with a substantially rectangular tube  111  at a front part and a wire crimping portion  112  in the form of an open barrel near a rear part. A coupling  113  joins the rear end of the tube  111  and the front end of the wire crimping portion  112 . A width direction and a lateral direction are synonymous in the following description. 
     A long narrow bottom plate  114  extends continuously in forward and backward directions along the tube  111 , the coupling  113  and the wire crimping portion  112 . A front part of the bottom plate  114  is substantially flat and of substantially constant width to define a bottom wall  115  of the rectangular tube  111 . A rear part of the bottom plate  114  is curved to bulge down and out to define a crimping area  116  of the wire crimping portion  112 . An area of the bottom plate  114  between the bottom wall  115  and the crimping area  116  in forward and backward directions is a substantially flat plate and defines a coupling area of the coupling portion  113 . 
     As shown in  FIGS. 9 ,  13  and  14 , the tube  111  includes left and right side plates  118  extending at substantially right angles from opposite widthwise sides of the bottom wall  115 , two ceiling plates  119  extending at substantially right angles from the extending upper ends of the respective side plates  118  and at least partly placed one over the other. Each ceiling plate  119  is divided into a front plate  119 F and a rear plate  119 R, and the height of the rear plate  119 R from the bottom plate  114  is lower than the front plate  119 F so that a step is formed therebetween. 
     As shown in  FIG. 12 , a resilient contact piece  120  is folded back from the front end of the inner front ceiling plate  119 F and is cantilevered back into the tube  111 . Similarly, an auxiliary resilient piece  121  is cantilevered forward from the inner rear ceiling plate  119 R. The auxiliary resilient piece  121  has a function of increasing a resilient force of the resilient contact piece  120  by contacting the upper surface of the resilient contact piece  120 . 
     As shown in  FIGS. 12 and 13 , a part of the bottom wall  115  of the tube  111  is struck, deformed or bent up and in toward the resilient contact piece  120  to form a receiving portion  122 . The receiving portion  122  includes a substantially flat receiving surface  123  that is long and narrow in forward and backward directions and faces the lower surface of the resilient contact piece  120 . The receiving surface  123  is substantially parallel to an area of the bottom wall  115  of the tube  111  where the receiving portion  122  is not formed. As shown in  FIG. 12 , a formation area of the receiving portion  122  in forward and backward directions extends from a position slightly behind the front end of the bottom wall  115  of the tube  111  to a position slightly before the rear end of the bottom wall  115  of the tube  111 . As shown in  FIGS. 11 and 13 , a formation area of the receiving portion  122  in a width direction particularly is a central part of the bottom wall  115 . 
     A tab of a mating terminal (not shown) inserted into the tube  111  from the front moves between the resilient contact piece  120  and the receiving portion  122  while resiliently deforming the resilient contact piece  120  and the auxiliary resilient piece  121  up and out away from the base plate  114 . The tab is held in substantially surface contact with the receiving surface  123  by resilient restoring forces of the resilient contact piece  120  and the auxiliary resilient piece  121  and the tab and the resilient contact piece  120  are connected at a specified contact pressure. As shown in  FIG. 12 , a contact  124  of the resilient contact piece  120  with the tab is before the rear end of the receiving portion  122 . 
     As shown in  FIGS. 10 to 12 , the crimping area  116  of the wire crimping portion  112  has a front crimping portion  116 F and a rear crimping portion  116 R. A wire barrel  112 F comprises the front crimping portion  116 F and two first crimping pieces  125 F extend from opposite widthwise sides of the front crimping portion  116 F. The wire barrel  112 F is to be crimped, bent or folded and connected to a conductor exposed by stripping an insulation coating at a front end portion of a wire (not shown). An insulation barrel  112 R comprises the rear crimping portion  116 R and two second crimping pieces  125 R extend from the opposite widthwise sides of the rear crimping portion  116 R. The insulation barrel  112 R is crimped, bent or folded and connected to a part of the front end portion of the wire surrounding the conductor. 
     As shown in  FIGS. 10 and 12 , if an area of the outer or lower surface of the bottom wall  115  of the rectangular tube  111  where the receiving portion  122  is not formed is a reference surface S, an intermediate part of the outer surface of the front crimping portion  116 F, which is lowest in the width direction, is located slightly higher than the reference surface S. On the other hand, an intermediate part of the outer surface of the rear crimping portion  116 R lowest in the width direction is located at a position lower than the reference surface S. Thus, the lowest position of the rear crimping portion  116 R is lower than the bottom wall  115 . This lowest end of the rear crimping portion  116 R is located at the lowest position of the entire terminal fitting  110 . 
     The coupling portion  113  is formed so that the laterally symmetric coupling plates  126  project up from opposite left and right sides of the coupling area  117  of the bottom plate  114 . As shown in  FIG. 11 , the coupling area  117  has a substantially isosceles trapezoidal planar shape symmetrical with respect to an axis in forward and backward directions. The front end of the coupling area  117  is narrower than that of the rear end of the coupling area  117 . As shown in  FIGS. 10 to 12 , the coupling area  117  is not a flat plate, but comprises a front and rear plates  117 F and  117 R connected at a lateral boundary line. As shown in  FIG. 10 , the front plate  117 F is substantially flush with a rear end of the bottom wall  115  of the rectangular tube  111 . The rear plate-like area  117 R is inclined up to the back with respect to the front plate-like area  117 F. 
     The front ends of coupling plates  126  are connected to the rear ends of the side plates  118  and the rear ends thereof are connected to the front ends of base parts of the first crimping pieces  125 F. The upper extending ends of the coupling plates  126  are free ends and not directly connected to other parts. Accordingly, the coupling plates  126  are relatively easily deformable as compared with the side plates  118 , which are difficult to deform because the ceiling plates  119  are placed thereon and the crimping pieces  125 F to be crimped and connected to the wire. Thus, the coupling  113  has relatively low strength as compared with the tube  111  and the wire crimping portion  112 . 
     Accordingly, at least one reinforcement  127  is formed on the bottom plate  114  to increase the strength of the coupling  113 . The reinforcement  127  comprises a long narrow rib extending continuously in forward and backward directions and formed by striking, embossing or stamping part of the bottom plate  114  down and outward of the tube  111 . As shown in  FIGS. 10 to 12 , a formation area of the reinforcement  127  in forward and backward directions extends from a position slightly behind the rear end of the receiving portion  122  of the bottom wall  115  to the rear end of the front plate  117 F of the coupling  117 . As shown in  FIGS. 9 and 11 , a formation area of the reinforcement  127  in the width direction is only central widthwise parts of the tube  111  and/or the coupling  113 . 
     As shown in  FIG. 14 , a cross-sectional shape of the reinforcement  127  cut along a plane perpendicular to forward and backward directions is a substantially laterally symmetrical triangular or pointed shape. As shown in  FIG. 12 , a front end part and a rear end part of the reinforcement  127  are bent in a step-like manner. Further, a rear part of the receiving portion  122  arranged before and proximate to the front end part of the reinforcement  127  also is bent in a step-like manner. Accordingly, an area extending from the rear end part of the receiving portion  122  to the front end part of the reinforcement  127  is bent in a stepwise manner. An area of the lower or outer surface of the front plate  117 F of the coupling  117  where the reinforcement  127  is not formed is connected substantially flush with the lower surface of the bottom wall  115  of the tube  111  and forms the reference surface S. Thus, the lowest end of the lower or outer surface of the rear crimping portion  116 R is below (more outward) an area of the lower surface of the front plate  117 F where the reinforcement  127  is not formed. As shown in  FIG. 12 , a projecting distance Pa of the reinforcement  127  from the reference surface S is slightly longer than a height difference Pb between the reference surface S and the rear crimping area  116 . 
     As described above, the coupling area  117  of the coupling  113  is partially struck, bent, hammered, deformed or embossed out to form the at least one reinforcement  127 . Thus, the strength of the coupling area  117  is increased. In addition, the reinforcement  127  is substantially continuous from the coupling area  117  to the bottom wall  115  of the tube  111 . Thus, the strength of the narrow front part of the coupling  113 , i.e. a boundary between the rear end of the rectangular tube  111  and the front end of the coupling  113  is increased. 
     Further, the formation area of the reinforcement  127  in the width direction is only a part of the base plate  114  in the width direction. The technical significance of this formation range is as follows. As shown in  FIG. 9 , the rectangular tube  111  of the terminal fitting  110  is inserted into a terminal accommodating chamber  130  with small clearances between the bottom wall  115 , the side plates  18  and the ceiling plates  119  and the inner wall of the terminal accommodating chamber  130 . Here, the bottom wall of the terminal accommodating chamber  130  is formed with at least one escaping groove  131  for avoiding interference with the reinforcement  127 . The reinforcement  127  is inserted into the escaping groove  131  with a small clearance formed therebetween when the tube  111  is inserted in a proper posture into the terminal accommodating chamber  130 . 
     However, if the terminal fitting  110  is inserted in an improper (e.g. upside-down) posture into the terminal accommodating chamber  130 , the front end of the reinforcement  127  interferes with an opening edge at the entrance of the terminal accommodating chamber  130  and the tube  111  cannot be inserted into the terminal accommodating chamber  130 . The reinforcement  127  also functions as a stabilizer for preventing the terminal fitting  110  from being inserted in an improper posture into the terminal accommodating chamber  130 . The terminal fitting  110  has a simple shape as compared with a terminal fitting in which a dedicated stabilizer is formed separately from the reinforcement  127 . 
     The reinforcement  127  is struck, embossed, hammered or stamped to locally project down from the reference surface S (outer surfaces of the bottom wall  115  and the front plate  117 F), external matter approaching from below may interfere with the reinforcement  127 . However, the rear crimping portion  116 R of the crimping area  16  forming the wire crimping portion  112  is located below the reference surface S and a space below the reference surface S becomes a dead space due to a height difference between the reference surface S and the rear crimping portion  116 R. A part of the reinforcement  127  is accommodated in this dead space and a projecting distance of the reinforcement  127  from the outermost end position of the outer surface (lower surface) of the base plate  114  (lowest end position of the rear crimping portion  116 ) is suppressed to be short. Thus, even if external matter approaches from below, it is difficult for the external matter to interfere with the reinforcing portion  127  due to the presence of the rear crimping portion  116 R. 
     The invention is not limited to the above described embodiment. For example, the following embodiments also are included in the scope of invention. 
     The formation area of the reinforcement  127  in forward and backward directions extends from the coupling area  117  to the bottom wall  115  in the above embodiment, but it may be limited to the range of the coupling area  117  or may extend substantially over all the areas of the bottom wall  115 , the coupling area  117  and the crimping area  116  or may be limited to a range extending from the coupling area  117  to the crimping area  116 . 
     The area of the reinforcement  127  in forward and backward directions in the coupling area  117  is only a front end part of the coupling area  117 , but it may be substantially the entire coupling area  117  from the front end to the rear end or may be only a central part of the coupling area  117  in forward and backward directions or may be only a rear end part of the coupling area  117 . 
     Although the reinforcement  127  is arranged in the widthwise center in the above embodiment, it may be arranged at a position displaced either to the left or right in the width direction. 
     One reinforcement  127  is provided in the above embodiment, but a plurality of reinforcements may be formed on one terminal fitting  110 . In this case, the reinforcements may be arranged substantially side by side in the width direction or in forward and backward directions. 
     Although the reinforcement  127  has a triangular cross-sectional shape in the above embodiment, but the cross-sectional shape of the reinforcement may be a rectangular shape, a trapezoidal shape or an arcuate shape other than the triangular shape. 
     Although the reinforcing portion  127  also functions as a stabilizer in the above embodiment, a dedicated stabilizer may be formed separately from the reinforcing portion  127 . 
     Although the terminal fitting  110  is a female terminal including the resilient contact piece  120  in the rectangular tube  111  in the above embodiment, the invention can be applied to a male terminal including a long and narrow tab projecting forward from a rectangular tube. 
     In the above embodiment, the projecting distance Pa of the reinforcement  127  from the reference surface S (area of the lower surface of the coupling area  117  where the reinforcement  127  is not formed) is longer than the height difference Pb between the reference surface S and the rear crimping area  116  and only a part of the reinforcement  127  is accommodated in the deal space formed below the reference surface S due to the height difference Pb. However, since the height difference Pb varies due to the thickness of the wire to which the wire crimping portion  112  is crimped and connected, there is no limitation to the above embodiment and the projecting distance Pa of the reinforcing portion  127  may be substantially equal to or shorter than the height difference Pb. If the height difference Pb is longer than the projecting distance Pb, the entire reinforcement  127  is accommodated in the dead space formed below the reference surface S due to the height difference Pb and hidden behind the wire crimping portion  112  when the terminal fitting  110  is viewed from behind. 
     A third embodiment of the invention is described with reference to  FIGS. 15 to 22 . A long narrow terminal fitting  210  of this embodiment is formed by bending, folding and/or embossing a conductive metal plate material  211  having a given thickness and punched or cut out into a shape shown in  FIG. 22 . A substantially rectangular tube  212  formed near a front end part of the terminal fitting  210  and a wire crimping portion  213  in the form of at least one open barrel to be connected to a wire is formed near a rear end of the terminal fitting  210 . A coupling  214  of substantially U-shaped cross-section joins a rear end of the tube  212  and a front end of the wire crimping portion  213 . In the following description, left side of  FIGS. 16 to 19  is referred to as the front concerning forward and backward directions and lateral direction is based on  FIGS. 15 ,  20  and  21 . 
     As shown in  FIG. 16 , the terminal fitting  210  is to be inserted from behind into a terminal accommodating chamber  231  formed in a housing  230  made e.g. of synthetic resin. A locking lance  232  is cantilevered forward from the upper or inner wall of the terminal accommodating chamber  231 . The locking lance  232  retains the terminal fitting  210  that has been inserted properly into the terminal accommodating chamber  231 . A tab of a mating terminal (not shown) can be inserted into the terminal accommodating chamber  231  and into the tube  212  from the front. 
     As shown in  FIGS. 15 to 18 , the rectangular tube  212  includes a base plate  215 , a right side plate  216 R, a left side plate  216 L, two ceiling plates  217 H,  217 L, a resilient contact piece  223  and an auxiliary spring piece  224 . The base plate  215  has a substantially rectangular shape long and narrow in forward and backward directions. 
     The right side plate  216 R is substantially is long and narrow in forward and backward directions and projects at a substantially right angle from a right side of the base plate  215 , when viewed from the front, as shown in  FIG. 15 , and extends in forward and backward directions along substantially the entire base plate  215 . As shown in  FIG. 16 , the upper end of the right side plate  216 R is higher on a front part and an area behind the front part is lowered while forming at least one step. The left side plate  216 L also is long and narrow in forward and backward directions and projects at a substantially right angle from the left side of the base plate  215 , when viewed from the front, as shown in  FIG. 15 , and extends along substantially the entire base plate in forward and backward directions. As shown in  FIG. 18 , the upper end of the left side plate  216 L is higher in a front area than in a rear area to form at least one step. 
     As shown in  FIG. 18 , the two ceiling plates  217 H,  217 L comprise an inner ceiling plate  217 L, which is not exposed on the outer surface of the tube  212 , and an outer ceiling plate  217 H, which conceals the inner ceiling plate  217 L and is exposed on the outer surface of the tube  212 . The inner ceiling plate  217 L is divided into a front inner plate  218 F and a rear inner plate  218 R. The outer ceiling plate  217 H similarly is divided into a front outer plate  219 F and a rear outer plate  219 R. 
     As shown in  FIG. 16 , the front inner plate  218 F is cantilevered at a substantially right angle from the upper end of the right side plate  216 R and is substantially parallel to the base plate  215 . As shown in  FIG. 20 , a front locking projection  220 F is formed on the extending free end of the front inner plate  218 F. The front outer plate  219 F extends from the elevated front area of the upper end of the left side plate  216 L and is substantially parallel to the base plate  215 . As shown in  FIGS. 19 and 20 , the front outer plate  219 F faces and is parallel to the outer surface of the front inner plate  218 F while forming a specified clearance S therebetween. The rear end edge of the front outer plate  219 F serves as a lock  221  to be engaged with the locking lance  232 . 
     As shown in  FIG. 20 , a front locking hole  222 F is formed at a corner where the upper end of the left side plate  216 L and the left end of the front outer plate  219 F meet at a substantially right angle. The front locking projection  220 F is inserted and locked in the front locking hole  222 F so that the front inner plate  218 F and the front outer plate  219 F are positioned in a state where relative displacements in vertically separating directions are restricted. The vertical direction means a direction in which the tab is sandwiched between the resilient contact piece  223  and the base plate  215 , i.e. a direction in which the resilient contact piece  223  is resiliently deformed. 
     As shown in  FIG. 18 , a base end of the resilient contact piece  223  is connected to the front end of the front inner plate  218 F. The resilient contact piece  223  is folded back to cantilever obliquely down and in to the back from the front end of the front inner plate  218 F and is resiliently deformable vertically toward and away from the base plate  215  with the base end as a support. A clearance between the base plate  215  and the resilient contact piece  223  in the vertical direction is narrowed gradually from the front to the rear and is narrowest at a rear end of the resilient contact piece  223 . The tab inserted into the tube  212  from the front moves between the base plate  215  and the resilient contact piece  223  to resiliently displace the resilient contact piece  223  away from the base plate  215 . Thus, the tab is sandwiched resiliently between the resilient contact piece  223  and the base plate  215  by a resilient restoring force of the resilient contact piece  223 . 
     As shown in  FIG. 16 , the rear inner plate  218 R is cantilevered at a substantially right angle from the lowered upper end of the rear part of the right side plate  216 R and is substantially parallel to the base plate  215 . The height of the upper surface of the rear inner plate  218 R from the base plate  215  is lower than that of the lower surface of the front inner plate  218 F. A rear locking projection  220 R is formed on the extending end of the rear inner plate  218 R. The rear outer plate  219 R extends at a right angle from the lowered upper end of the rear part of the left side plate  216 L, is substantially parallel to the base plate  215  and is placed on the outer surface of the rear inner plate  218 R. 
     The height of the upper surface of the rear outer plate  219 R from the base plate  215  is lower than that of the lower surface of the front inner plate  218 F. A rear locking hole  222 R is formed at a position near the upper end of the left side plate  216 L. As shown in  FIG. 18 , the rear locking projection  220 R is inserted and locked in the rear locking hole  222 R so that the rear inner plate  218 R, the left side plate  216 L and the rear outer plate  219 R are positioned in a state where relative vertical displacements are restricted. 
     As shown in  FIG. 18 , the auxiliary spring piece  224  is cantilevered forward from the front end of the rear inner plate  218 R and is resiliently deformable vertically toward and away from the base plate  214  with a rear end as a support. A front end part of the auxiliary spring piece  224  serves as a support  225  for increasing a resilient force of the resilient contact piece  223 . The support  225  is arranged to contact the rear part of the resilient contact piece  223  from above or outside. 
     The auxiliary spring piece  224  extends substantially parallel to the base plate  215 , but has a bend  226  that is bent up at an intermediate position of the auxiliary spring piece  224  in an extending direction and behind the support  225 . As compared with the case where the bend  226  is not formed, a part of the auxiliary spring piece  224  before the bend  226  is displaced up toward the locking lance  232  by an elevation dimension of the bend  226 . An area of the auxiliary spring piece  224  where the bend  226  is formed is exposed to a side above the tube  212  between the rear end of the front outer plate  219 F and the front end of the rear outer plate  219 R. 
     When the tab is inserted between the resilient contact piece  223  and the base plate  215  to resiliently displace the resilient contact piece  223 , the rear end part of the resilient contact piece  223  pushes the support  225  up to resiliently displace the auxiliary spring piece  224  up and away from the base plate  214 . Then, the support  225  presses the resilient contact piece  223  toward the tab due to the resilient restoring force of the auxiliary spring piece  224 . Therefore the resilient force of the resilient contact piece  223  is increased to increase a contact pressure between the resilient contact piece  223  and the tab. 
     In the terminal fitting  210  of the third embodiment, the tube  212  is formed by bending, folding and/or embossing the conductive metal plate material  211  punched or cut into the specified shape. To improve material yield, the height (elevation from the base plate  215 ) of the right side plate  216 R connected to the inner ceiling plate  217 L, particularly the height of the front end area connected to the front inner plate  218 F is reduced. However, since the clearance S is formed between the front outer plate  219 F (outer ceiling plate  217 H) and the front inner plate  218 F (inner ceiling plate  217 L) by reducing the height of the front end area of the right side plate  216 R, the shape of the front part of the tube  212  may become unstable. Accordingly, a projection  227  is formed on the front inner plate  218 F to stabilize the shape of the tube  212  while improving material yield. 
     As shown in  FIGS. 19 ,  20  and  22 , the projection  227  is formed by striking part of the front inner plate  218 F up toward the front outer plate  219 F. A formation area of the projection  227  in forward and backward directions is an intermediate part of the front inner plate  218 F and a formation area of the projection  227  in the lateral direction also is an intermediate part of the front inner plate  218 F. The projection  227  has a substantially rectangular planar shape. The upper surface of the projection  227  is a substantially flat contact surface parallel to an area of the upper surface of the front inner plate  218 F where the projection  227  is not formed and the lower surface of the front outer plate  219 F. This contact surface  228  of the projection  227  is held substantially in surface contact with the lower surface of the front outer plate  219 F. 
     Relative displacements of the plates  218 F,  219 F in the vertical separating directions are restricted by the engagement of the front locking hole  222 F and the front locking projection  220 F and relative displacements of the plates  218 F,  219 F in vertical approaching directions are restricted by the projection  227 . By this restricting structure, even if a distance (clearance S) between the front inner plate  218 F and the front outer plate  219 F is widened to improve material yield, a positional relationship of the front inner plate  218 F and the front outer plate  219 F in the vertical direction is stabilized and the shape of the rectangular tube  212  is stabilized. Thus, the shape of the rectangular tube  212  can be stabilized while material yield is improved. 
     A contact area of the projection  227  with the front outer plate  219 F is the flat contact surface  228  parallel to the inner surface of the front outer plate  219 F. Thus, the projection  227  and the front outer plate  219 F come into surface contact. This makes it difficult for the front inner plate  218 F and the front outer plate  219 F to be inclined relative to each other in forward and backward directions and lateral direction. Therefore the shape of the rectangular tube  212  is stabilized more. 
     The terminal fitting  210  includes the front outer plate  219 F arranged in a front area of the rectangular tube  212 , the rear outer plate  219 R having a shorter height from the base plate  215  than the front outer plate  219 F and arranged behind the front outer plate  219 F, and the locking portion  221  on the rear end edge of the front outer plate  219 F. The locking portion  221  retains the tube  212  (terminal fitting  210 ) by being engaged with the locking lance  232  formed on the inner wall of the terminal accommodating chamber  231  when the tube  212  is inserted in the terminal accommodating chamber  231 . This configuration means that the locking portion  221  utilizes a height difference between the front outer plate  219 F and the rear plate  219 R. 
     Furthermore, the terminal fitting  210  includes the resilient contact piece  223  folded to cantilever back from the front end of the front inner plate  218 F, the auxiliary spring piece  224  cantilevered forward from the rear inner plate  218 R and supporting the resilient contact piece  223  from the side of the locking lance  232  at the support  225  on the extending end, and the bend  226  formed on the auxiliary spring piece  224  and substantially bent to bring an area behind the support  225  closer to the locking lance  232 . 
     The technical significance of providing the bend  226  is as follows. In the case of displacing the rear inner plate  218 R down or in toward the base plate  215  so as to be more distant from the locking lance  232  to increase an engagement margin of the locking lance  232  with the locking portion  221 , the auxiliary spring piece  224  also is displaced to a position more distant from the locking lance  232 . Thus, if the bend  226  is not formed and the auxiliary spring piece  224  extends obliquely down and in to the front from the front end of the rear inner plate  218 R, the support  225  of the auxiliary spring piece  224  is located at a side of the resilient contact piece  223  substantially opposite to the locking lance  232  (as if to slip under the resilient contact piece  223 ). As a result a supporting function by the auxiliary spring piece  224  may be lost. However, the bend  226  is bent to approach the locking lance  232  and is formed in an area of the auxiliary spring piece  224  behind the support  225  for the resilient contact piece  223 . Thus, the support  225  is displaced toward the locking lance  232  as compared with the case where the bend  226  is not formed. Therefore, the support  225  can properly come into contact with and support the resilient contact piece  223  from the side of the locking lance  232 . 
     A fourth embodiment of the invention is described with reference to  FIGS. 23 to 25 . In a terminal fitting  240  of the fourth embodiment, a projection  241  is formed at a position different from that in the above third embodiment. Since other configurations are similar or substantially the same as in the above third embodiment, the similar or substantially same configurations are denoted by the same reference numerals and structures, functions and effects thereof are not described. 
     Although the projection  227  is formed on the front inner plate  218 F and comes into contact with the inner surface (lower surface) of the front outer plate  219 F in the terminal fitting  210  of the above third embodiment, the projection  241  is formed on the front outer plate  219 F and projects down or in the terminal fitting  240  of the fourth embodiment. This projection  241  includes a contact surface  242  which is a substantially flat surface, and the contact surface  242  is held substantially in surface contact with the outer surface (upper surface) of the front inner plate  218 F. 
     The invention is not limited to the above described embodiments. For example, the following embodiments also are included in the scope of the invention. 
     Although the projection is formed only on either one of the pair of ceiling plates in the above third and fourth embodiments, the projection may be formed on each of the pair of ceiling plates. In this case, the both projections may be brought into contact with areas of the other ceiling plates where the projections are not formed or may be brought into contact with each other. 
     Although the contact area of the projection with the other ceiling plate is a flat surface parallel to the other ceiling plate in the above third and fourth embodiments, it may be a long and narrow line or may be narrow and locally limited such as a point. 
     Although the projection is in contact with the other ceiling plate only at one position in the above third and fourth embodiments, one projection may be in contact with the other ceiling plate at a plurality of positions. 
     Although one projection is formed on one ceiling plate in the above third and fourth embodiments, a plurality of projections may be formed on one ceiling plate. 
     Although the projecting portion is formed only on the front plate (front inner plate or front outer plate) in the above third and fourth embodiments, it may be formed on both the front projecting and the rear plate or may be formed only on the rear plate. 
     Although the projecting portion is formed by striking in the above third and fourth embodiments, it may be formed by cutting and bending. 
     Although the resilient contact piece is directly connected to the front inner plate (inner ceiling plate) in the above third and fourth embodiments, it may not be directly connected to the resilient contact piece. 
     Although the locking lance is engaged with the ceiling plate in the above third and fourth embodiments, it may be engaged with a part different from the ceiling plate.