Patent Publication Number: US-2022216636-A1

Title: Connector

Description:
TECHNICAL FIELD 
     The present disclosure relates to a connector. 
     BACKGROUND 
     Patent Document 1 discloses a connector in which a terminal fitting is inserted in a terminal accommodation chamber of a connector housing. An insertion hole for the insertion of a tab of a mating terminal into the terminal accommodation chamber is open in a front wall portion of the connector housing. The tab inserted into the insertion hole contacts an electrical contact portion in a front end part of the terminal fitting. 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent Document 1: JP H09-043299 A 
     SUMMARY OF THE INVENTION 
     Problems to be Solved 
     When continuity inspection is carried out in the connector of Patent Document 1, an inspection pin is inserted into the insertion hole and the tip of the inspection pin is butted against the electrical contact portion. The electrical contact portion is an important part in terms of functions as the terminal fitting. Thus, if the inspection pin is butted against the electrical contact portion, there is a concern that the electrical contact portion may be deformed and the terminal fitting cannot exhibit original functions. 
     A connector of the present disclosure was completed on the basis of the above situation and aims to prevent the damage and deformation of a terminal fitting. 
     Means to Solve the Problem 
     The present disclosure is directed to a connector with a housing including a terminal accommodation chamber, and a terminal fitting including a tube portion and a resilient contact piece accommodated in the tube portion, the terminal fitting being inserted into the terminal accommodation chamber, wherein a front wall portion of the housing is formed with a tab insertion hole, a tab of a mating terminal being inserted into the tab insertion hole to enter the tube portion from front and contact the resilient contact piece, a front plate portion is formed forward of the resilient contact piece in the terminal fitting, the front wall portion of the housing is formed with a detection hole open separately from the tab insertion hole, and the detection hole is disposed at a position facing the front plate portion in the front wall portion. 
     Effect of the Invention 
     According to the present disclosure, it is possible to prevent the damage and deformation of a terminal fitting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of a connector of a first embodiment. 
         FIG. 2  is a side view in section showing a state where a detection pin inserted into a detection hole is in contact with a front plate portion of a terminal fitting. 
         FIG. 3  is a side view in section showing a state of the terminal fitting pushed rearward by the detection pin. 
         FIG. 4  is a perspective view of the terminal fitting. 
         FIG. 5  is a front view in section showing the state where the detection pin is in contact with the front plate portion of the terminal fitting. 
         FIG. 6  is a front view of a terminal fitting of a second embodiment. 
         FIG. 7  is a perspective view of a terminal fitting of a third embodiment. 
         FIG. 8  is a front view of a terminal fitting of a fourth embodiment. 
     
    
    
     DETAILED DESCRIPTION TO EXECUTE THE INVENTION 
     Description of Embodiments of Present Disclosure 
     First, embodiments of the present disclosure are listed and described. 
     (1) The connector of the present disclosure is provided with a housing including a terminal accommodation chamber, and a terminal fitting including a tube portion and a resilient contact piece accommodated in the tube portion, the terminal fitting being inserted into the terminal accommodation chamber, wherein a front wall portion of the housing is formed with a tab insertion hole, a tab of a mating terminal being inserted into the tab insertion hole to enter the tube portion from front and contact the resilient contact piece, a front plate portion is formed forward of the resilient contact piece in the terminal fitting, the front wall portion of the housing is formed with a detection hole open separately from the tab insertion hole, and the detection hole is disposed at a position facing the front plate portion in the front wall portion. 
     According to the configuration of the present disclosure, a detection pin is inserted into the detection hole and brought into contact with the front plate portion at the time of continuity inspection. Since the front plate portion is located forward of the resilient contact piece, there is no possibility that the detection pin contacts the resilient contact piece. Since the detection hole is open separately from the tab insertion hole and the tab insertion hole and the detection hole do not communicate with each other, there is also no possibility that the detection pin inserted into the detection hole erroneously enters the tab insertion hole to contact resilient contact piece. Therefore, according to the connector of the present disclosure, the damage and deformation of the terminal fitting due to the contact of the detection pin can be prevented. 
     (2) Preferably, the front plate portion is cantilevered from a plate-like portion constituting the tube portion, and the detection hole is disposed eccentrically from a center of a cross-section of the tube portion orthogonal to an entering direction of the tab. According to this configuration, since the detection hole is eccentric toward the plate-like portion from the center of the cross-section of the tube portion orthogonal to the entering direction of the tab, i.e. a center of the tube portion in a front view, the detection pin pushes not a part of the front plate portion near an extending end part, but a part of the front plate portion on the side of a base end part connected to the plate-like portion. Therefore, there is no possibility that the front plate portion is deformed rearward even if being pushed by the detection pin. 
     (3) In (2), preferably, the detection hole is facing a region of the front plate portion including a base end part connected to the plate-like portion. According to this configuration, since the detection pin can push the base end part of the front plate portion connected to the plate-like portion, the rearward deformation of the front plate portion can be reliably prevented when the front plate portion is pushed by the detection pin. 
     (4) Preferably, the front plate portion covers at least a part of the resilient contact piece from front. According to this configuration, even in a state where the terminal fitting is located outside the terminal accommodation chamber, the damage and deformation of the resilient contact piece due to the interference of an external matter can be prevented. 
     (5) Preferably, a rear end of the detection hole is open to face a region of the terminal fitting, where the front plate portion is not formed, in a front-rear direction, and at least a rear end part of an inner peripheral surface of the detection hole is formed with a guide slope inclined to approach the front plate portion toward a rear side. According to this configuration, the detection pin can be reliably inserted into the detection hole by making an inner diameter of the front end of the detection hole larger than the detection pin. The detection pin inserted into the detection hole can reliably contact the front plate portion by sliding in contact with the guide slope. 
     (6) In (5), preferably, the terminal fitting is retained by a resiliently displaceable locking lance formed in the terminal accommodation chamber, and the guide slope is formed by recessing an inner surface of the terminal accommodation chamber. A clearance is unavoidably formed in the front-rear direction between the terminal fitting and the resiliently displaceable locking lance, and the terminal fitting is displaceable in the front-rear direction by as much as this clearance. Focusing on this point, the guide slope is formed by recessing the inner surface of the terminal accommodation chamber. According to this configuration, the detection pin can increase a contact area with the front plate portion by sliding in contact with the guide slope in the process of the terminal fitting moving rearward by as much as the clearance between the terminal fitting and the locking lance by being pushed by the detection pin. 
     Details of Embodiments of Present Disclosure 
     First Embodiment 
     A first specific embodiment of a connector of the present disclosure is described with reference to  FIGS. 1 to 5 . In the first embodiment, a left side in  FIGS. 2 and 3  is defined as a front side concerning a front-rear direction. Upper and lower sides shown in  FIGS. 1 to 5  are directly defined as upper and lower sides concerning a vertical direction. Left and right sides shown in  FIGS. 1 and 5  are directly defined as left and right sides concerning a lateral direction. 
     The connector of the first embodiment includes a housing  10  (see  FIGS. 1 and 2 ) and a plurality of terminal fittings  30  (see  FIGS. 2 to 4 ). The housing  10  includes a housing body  11  made of synthetic resin and a retainer  12  made of synthetic resin and mounted on a rear end part of the housing body  11  and has a rectangular parallelepiped shape long in the lateral direction as a whole. A plurality of terminal accommodation chambers  13  elongated in the front-rear direction are formed side by side in the lateral direction in the housing  10 . The terminal fitting  30  is inserted into each terminal accommodation chamber  13  from behind the housing  10 . Note that, in the following description, the lateral direction and a parallel direction of the terminal accommodation chambers  13  are used as synonyms. 
     As shown in  FIGS. 2 and 3 , the housing  10  includes a bottom wall portion  15  constituting a bottom surface  14  (inner surface as claimed) of the terminal accommodation chamber  13 . The bottom wall portion  15  is formed with a locking lance  16  cantilevered forward (in the same direction as an inserting direction of the terminal fitting  30  into the terminal accommodation chamber  13 ). The locking lance  16  is resiliently displaceable in the vertical direction (direction orthogonal to an extending direction of the locking lance  16 ) with a rear end part of the locking lance  16  as a fulcrum while facing the terminal accommodation chamber  13 . A front end part of the locking lance  16  functions as a retaining portion  17  for retaining the terminal fitting  30 . If the locking lance  16  is resiliently displaced in the vertical direction, the retaining portion  17  is displaced along an arcuate path. Note that, in the following description, the vertical direction and a resilient displacing direction of the locking lance  16  are used as synonyms. 
     The housing  10  includes a front wall portion  18  constituting a front surface portion of the terminal accommodation chamber  13 . In the first embodiment, the front wall portion  18  is a wall portion constituting the front surface of the housing  10 , out of an outer wall portion of the housing  10 . In the first embodiment, a range of the front surface of the housing  10  from the upper surface to the lower surface of the housing  10  is defined as the front wall portion  18 . The front wall portion  18  extends in a region above the terminal accommodation chambers  13  and a region below the terminal accommodation chambers  13 . 
     The front wall portion  18  is formed with a plurality of tab insertion holes  19  individually facing the plurality of terminal accommodation chambers  13 . The tab insertion hole  19  penetrates through the front wall portion  18  in the front-rear direction and extends from the front surface of the housing  10  to the front end of the terminal accommodation chamber  13 . In the vertical direction, the tab insertion hole  19  is disposed in an upper part of the front wall portion  18 . As shown by an imaginary line in  FIG. 5 , the tab insertion hole  19  is disposed in a lateral center of the terminal accommodation chamber  13 . As shown in  FIG. 2 , a tab T of a mating terminal is inserted into the tab insertion hole  19  from the front of the housing  10 . 
     The front wall portion  18  is formed with a plurality of detection holes  20  individually facing the plurality of terminal accommodation chambers  13 . As shown in  FIGS. 2 and 3 , the detection hole  20  has an axial direction oriented in the front-rear direction and penetrates through the front wall portion  18  in the front-rear direction. The detection hole  20  allows the front surface of the housing  10  and the front end of the terminal accommodation chamber  13  to communicate. The detection hole  20  and the tab insertion hole  19  do not directly communicate with each other and constitute holes independent of each other. 
     In the vertical direction, the detection hole  20  is disposed at a position separated downward from the tab insertion hole  19  (in a lower part of the front wall portion  18 ). An axis of the detection hole  20  is located substantially at the same height as the bottom surface  14  of the terminal accommodation chamber  13  (upper surface of the bottom wall portion  15 ). In particular, the axis of the detection hole  20  is located slightly above the bottom surface  14  of the terminal accommodation chamber  13 . As shown in  FIGS. 1 and 5 , the detection hole  20  is disposed at a position eccentric from and to the left of the tab insertion hole  19  in a front view. 
     As shown in  FIGS. 2 and 3 , the detection hole  20  includes a fixed-diameter hole portion, a guiding portion  22  and a guide hole portion  23 . The fixed-diameter hole portion  21  constitutes a major region of the detection hole  20 . The fixed-diameter hole portion  21  has a circular cross-sectional shape perpendicular to an axis. An inner diameter of the fixed-diameter hole portion  21  is constant from the front end to the rear end of the fixed-diameter hole portion  21 . The guiding portion  22  is connected to the front end of the fixed-diameter hole portion  21  and disposed in a front end part of the detection hole  20 . The guiding portion  22  has a conical shape expanded in diameter toward a front side, concentrically with the fixed-diameter hole portion  21 . The front end of the guiding portion  22  is open in the front surface of the housing  10 . That is, the detection hole  20  forms a circular opening in the front wall portion  18  (front surface of the housing  10 ). 
     The guide hole portion  23  is connected to the rear end of the fixed-diameter hole portion  21  and constitutes a rear end part of the detection hole  20 . The guide hole portion  23  is disposed only in a region behind the front wall portion  18  (front end of the terminal accommodation chamber  13 ) in the front-rear direction. Thus, a formation region of the detection hole  20  in the front-rear direction is a range from the front end of the front wall portion  18  to a position behind the rear end of the front wall portion  18  (front end of the terminal accommodation chamber  13 ). 
     Since the axis of the detection hole  20  is disposed at a position slightly above the bottom surface  14  of the terminal accommodation chamber  13 , a cross-sectional shape of the guide hole portion  23  perpendicular to an axis is non-circular. The guide hole portion  23  is open upward in the bottom surface  14  of the terminal accommodation chamber  13 . The rear end of the fixed-diameter hole portion  21  is open rearward in the front surface of the terminal accommodation chamber  13 . A guide slope  24  inclined to be gradually higher toward a rear side is formed in a lower half region of the inner periphery of the guide hole portion  23 . The guide slope  24  is inclined to reduce a height difference from the bottom surface  14  of the terminal accommodation chamber  13  toward the rear side. The guide slope  24  is formed by recessing the bottom surface  14  (inner surface) of the terminal accommodation chamber  13 . 
     As shown in  FIGS. 2 to 4 , the terminal fitting  30  is a female terminal including a tube portion  31  and a crimping portion  37 . The tube portion  31  includes a base plate portion  32  (lower plate portion), a left side plate portion  33  (plate-like portion as claimed), a right side plate portion  34  and an upper plate portion  35 . Since the base plate portion  32 , the left side plate portion  33 , the right side plate portion  34  and the upper plate portion  35  are in the form of flat plates, the tube portion  31  has a rectangular tube shape with open front and rear ends. That is, in a front view of the terminal fitting  30 , the tube portion  31  is rectangular. A projection  36  projecting downward (on an outer surface side of the tube portion  31 ) is formed on a front end part of the base plate portion  32 . The crimping portion  37  is in the form of an open barrel and connected to the rear end of the tube portion  31 . The crimping portion  37  is conductively crimped to a front end part of a wire  38 . 
     As shown in  FIGS. 2 and 3 , the terminal fitting  30  includes a resilient contact piece  40 . The resilient contact piece  40  is arcuately folded rearward from the front end of the base plate portion  32 , extends rearward and is accommodated in the tube portion. The resilient contact piece  40  is resiliently displaceable in the vertical direction (directions toward and away from the base plate portion  32 ) with a folded portion  41  (front end part) leading to the base plate portion  32  as a fulcrum. The resilient contact piece  40  includes a curved portion  42  connected to the rear end of the folded portion  41 . The curved portion  42  projects upward away from the base plate portion  32 . An upper end part of the curved portion  42  facing and at a shortest distance from the upper plate portion  35  serves as a contact point portion  43  capable of contacting the tab T. 
     As shown in  FIGS. 4 and 5 , the terminal fitting  40  includes bilaterally symmetrical left front plate portion  44  (front plate portion as claimed) and right front plate portion  45 . The left front plate portion  44  is cantilevered rightward at a right angle to the left side plate portion  33  from the front end edge of the left side plate portion  33  (plate-like portion different from the base plate portion  32  connected to the resilient contact piece  40 ). The right front plate portion  45  is cantilevered rightward at a right angle to the right side plate portion  34  from the front end edge of the right side plate portion  34  (plate-like portion different from the base plate portion  32  connected to the resilient contact piece  40 ). In a front view, the left and right side plate portions  33 ,  34  are arranged laterally side by side at a distance from each other in a laterally central part of the tube portion  31 . The left and right side plate portions  33 ,  34  are both located forward of the front end (folded portion  41 ) of the resilient contact piece  40  and protect at least the folded portion  41  of the resilient contact piece  40  from front. 
     The left front plate portion  44  has a rectangular front view shape with long sides oriented in the vertical direction as a whole. In particular, a protrusion  46  in flush with the left front plate portion  44  projects downward on a right end part (extending end part) of the lower edge of the left front plate portion  44 . The lower edge of the protrusion  46  is located at the same height as the lower surface (outer surface) of the base plate portion  32 . A lateral dimension of the left front plate portion  44  is slightly smaller than half the width of the tube portion  31 . The upper edge of the left front plate portion  44  is located below (toward the base plate portion  32 ) the contact point portion  43  of the resilient contact piece  40  and the lower edge of the tab insertion hole  19 . Out of the left front plate portion  44 , the lower end of a base end part  47  connected to the left side plate portion  33  is located above the upper surface of the base plate portion  32 . 
     The right front plate portion  45  has a rectangular front view shape with long sides oriented in the vertical direction as a whole. In particular, a protrusion  46  in flush with the right front plate portion  45  projects downward on a left end part (extending end part) of the lower edge of the right front plate portion  45 . The lower edge of the protrusion  46  is located at the same height as the lower surface (outer surface) of the base plate portion  32 . A lateral dimension of the right front plate portion  45  is slightly smaller than half the width of the tube portion  31 . The upper edge of the right front plate portion  45  is located below (toward the base plate portion  32 ) the contact point portion  43  of the resilient contact piece  40  and the lower edge of the tab insertion hole  19 . Out of the right front plate portion  45 , the lower end of a base end part  47  connected to the right side plate portion  33  is located above the upper surface of the base plate portion  32 . 
     The terminal fitting  30  is inserted into the terminal accommodation chamber  13  from behind the housing  10 . In an insertion process of the terminal fitting  30 , the locking lance  16  interferes with the projection  36  to be resiliently deformed downward. Since the projection  36  passes over the locking lance  16  when the terminal fitting  30  is inserted to a proper position, the locking lance  16  resiliently returns upward and the retaining portion  17  faces the projection  36  from behind. Therefore, when the terminal fitting  30  is going to be displaced rearward from the proper insertion position, the projection  36  butts against the retaining portion  17 , whereby the terminal fitting  30  is retained. 
     The retaining portion  17  (front end of the locking lance  16 ) when the locking lance  16  is resiliently deformed in the insertion process of the terminal fitting  30  is located more rearward than the retaining portion  17  when the locking lance  16  is not resiliently deformed. Accordingly, a clearance S is formed in the front-rear direction between the projection  36  and the retaining portion  17  in a state where the terminal fitting  30  is properly inserted and can be retained by the locking lance  16 . Thus, the terminal fitting  30  in the properly inserted state is movable in the front-rear direction with respect to the housing  10  by as much as the clearance S between a foremost end position (see  FIG. 2 ) where the left and right front plate portions  44 ,  45  are in contact with the front wall portion  18  and a rearmost end position (see  FIG. 3 ) where the projection  36  is in contact with the retaining portion  17  (front end of the locking lance  16 ). 
     When the connector having the terminal fittings  30  properly inserted therein and a mating connector (not shown) are connected, the tabs T of the mating terminals pass through the tab insertion holes  19 , are inserted into the tube portions  31  and enter between the contact point portions  43  and the upper plate portions  35  while resiliently deforming the resilient contact pieces  40  downward. In this way, the tabs T are sandwiched between the upper plate portions  35  and the contact point portions  43  and resiliently connected to the terminal fittings  30 . 
     A positional relationship of the detection hole  20  and the properly inserted terminal fitting  30  is as follows. As shown in  FIG. 5 , a part of a lower end part of the left front plate portion  44  including the protrusion  46  and a part of a lower end part of the right front plate portion  45  are disposed in an opening region of the fixed-diameter hole portion  21  of the detection hole  20 . The fixed-diameter hole portion  21  of the detection hole  20  is facing a region of the left front plate portion  44  including a lower end part of the base end part  47  connected to the left side plate portion  33 . In other words, the detection hole  20  is facing a part of the left front plate portion  44  eccentric toward the left side plate portion  33  from a right edge part (leading edge part in an extending direction from the left side plate portion  33  and a central part of the tube portion  31  in a front view). The rear end of the detection hole  20  is open to face also a region of the terminal fitting  30  where the front plate portion is not formed. 
     Continuity inspection is carried out after the terminal fittings  30  are inserted into the terminal accommodation chambers  13 . At the time of the continuity inspection, a rod-like detection pin P having a circular cross-section is inserted from the front of the housing  10 . An outer diameter of the detection pin P is smaller than a diameter (inner diameter) of the fixed-diameter hole portion  21  and larger than a radius of the fixed-diameter hole portion  21 . Further, the tapered guiding portion  22  is formed in the front end part of the detection hole  20 . Accordingly, even if the detection pin P is shifted in position in the vertical or lateral direction with respect to the detection hole  20 , the detection pin P is reliably inserted into the detection hole  20 . 
     The detection pin P inserted into the detection hole  20  advances in the fixed-diameter hole portion  21  and contacts the lower end part of the left front plate portion  44 . If a detection circuit is closed when the detection pin P contacts the left front plate portion  44 , it is judged that the terminal fitting  30  is inserted in the appropriate terminal accommodation chamber  13 . Unless the detection circuit is closed, it is judged that the terminal fitting  30  is not inserted in the appropriate terminal accommodation chamber  13 . 
     If the detection pin P is inserted into the detection hole  20  and pushes the left front plate portion  44 , the terminal fitting  30  moves rearward by as much as the clearance S between the projection  36  and the locking lance  16  and, during this time, the detection pin P slides in contact with the guide slope  24 . Since the guide slope  24  is inclined to approach the left front plate portion  44  from below toward the rear side, a contact area of the detection pin P and the left front plate portion  44  increases as the terminal fitting  30  moves rearward. 
     The connector of the first embodiment includes the housing  10  having the plurality of terminal accommodation chambers  13  and the plurality of terminal fittings  30  inserted into the terminal accommodation chambers  13 . The terminal fitting  30  includes the tube portion  31  and the resilient contact piece  40  accommodated in the tube portion  31 . The front wall portion  18  of the housing  10  is formed with the tab insertion holes  19  into which the tabs T of the mating terminals are inserted to enter the tube portions  31  and contact the resilient contact pieces  40  from front. That is, the tabs T inserted into the tab insertion holes  19  from the front of the housing  10  enter the tube portions  31  and contact the resilient contact pieces  40 . The left front plate portion  44  is formed forward of the resilient contact piece  40  in the terminal fitting  30 . The front wall portion  18  of the housing  10  is formed with the detection holes  20  open separately from the tab insertion holes  19 . The detection holes  20  are disposed at the positions facing the left front plate portions  44  in the front wall portion  18 . That is, the openings of the tab insertion hole  19  and the openings of the detection holes  20  do not directly communicate with each other and are in a non-communication state in a front view. 
     According to the connector of the first embodiment, the detection pin P is inserted into the detection hole  20  and brought into contact with the left front plate portion  44  at the time of the continuity inspection. Since the left front plate portion  44  is located forward of the resilient contact piece  40 , there is no possibility that the detection pin P contacts the resilient contact piece  40 . Since the detection hole  20  is open separately from the tab insertion hole  19  and the detection hole  20  and the tab insertion hole  19  do not communicate with each other, there is also no possibility that the detection pin P inserted into the detection hole  20  erroneously enters the tab insertion hole  19  to contact the resilient contact piece  40 . Therefore, according to the connector of the first embodiment, the damage and deformation of the resilient contact piece  40  due to the contact of the detection pin P can be prevented. 
     The left front plate portion  44  is cantilevered from the left side plate portion  33  constituting the tube portion  33 . In view of this form, the detection hole  20  is disposed eccentrically toward the left side plate portion  33  from a center of a cross-section of the tube portion  31  orthogonal to an entering direction of the tab T (center of the tube portion  31  in a front view). In this way, the detection pin P pushes not a part of the left front plate portion  44  near the extending end part (right end part), but a part of the left front plate portion  44  on the side of the base end part  47  connected to the left side plate portion  33 . Therefore, there is no possibility that the left front plate portion  44  is deformed rearward even if being pushed by the detection pin P. 
     The detection hole  20  is facing the region of the left front plate portion  44  including the base end part  47  connected to the left side plate portion  33 . According to this configuration, since the detection pin P pushes the base end part  47  connected to the left side plate portion  33 , out of the left front plate portion  44 , the rearward deformation of the left front plate portion  44  can be reliably prevented when the left front plate portion  44  is pushed by the detection pin P. 
     The left front plate portion  44  is formed to cover at least a part (folded portion  41 ) of the resilient contact piece  40  together with the right front plate portion  45  from front. According to this configuration, also in a state where the terminal fitting  30  is located outside the terminal accommodation chamber  13 , the damage and deformation of the resilient contact piece  40  (particularly, the folded portion  41 ) due to the interference of an external matter can be prevented. The folded portion  41  is an important part for specifying a resilient restoring force of the resilient contact piece  40 , i.e. a contact pressure with the tab T. Therefore, functions of the terminal fitting  30  can be prevented from being impaired by covering and protecting the folded portion  41  by the left and right front plate portions  44 ,  45 . 
     Since the inner diameter of the front end of the detection hole  20  is set larger than the outer diameter of the detection pin P, the detection pin P can be reliably inserted into the detection hole  20 . On the other hand, the rear end of the detection hole  20  is open to face a region of the front end part of the terminal fitting  30  where the left front plate portion  44  is not formed, i.e. a region below the base end part  47  of the left front plate portion  44  (quarter-circular portion on a left-lower corner of the tube portion  31  in  FIG. 5 ) in the front-rear direction. Thus, it may not be possible to secure a sufficient contact area of the detection pin P and the left front plate portion  44 . 
     Accordingly, in the first embodiment, the guide slope  24  inclined obliquely upward to approach the left front plate portion  44  toward the rear side is formed on the rear end part (guide hole portion  23 ) of the inner peripheral surface of the detection hole  20 . According to this configuration, the detection pin P inserted into the detection hole  20  can reliably contact the left front plate portion  44  by sliding in contact with the guide slope  24 . 
     The terminal fitting  30  is retained by the locking lance  16  resiliently displaceably formed in the terminal accommodation chamber  13 . Thus, the clearance S is unavoidably formed in the front-rear direction between the terminal fitting  30  and the resiliently displaceable locking lance  16 , and the terminal fitting  30  is displaceable in the front-rear direction by as much as this clearance S. In view of this point, the guide slope  24  is formed by recessing the inner surface of the terminal accommodation chamber  13 . According to this configuration, the detection pin P can increase the contact area with the left front plate portion  44  by sliding in contact with the guide slope  24  in the process of the terminal fitting  30  moving rearward by as much as the clearance S between the terminal fitting  30  and the locking lance  16  by being pushed by the detection pin P. 
     Second Embodiment 
     A second specific embodiment of the present disclosure is described with reference to  FIG. 6 . The second embodiment is different from the first embodiment in the configurations of a left front plate portion  51  (plate-like portion as claimed) and a right front plate portion  52  of a terminal fitting  50 . Since the other components are the same as in the first embodiment, the same components are denoted by the same reference signs and structures, functions and effects thereof are not described. 
     The left front plate portion  51  is cantilevered rightward at a right angle to a left side plate portion  33  from the front end edge of the left side plate portion  33 . The right front plate portion  52  is cantilevered leftward at a right angle to a right side plate portion  34  from the front end edge of the right side plate portion  34 . An extension dimension of the left front plate portion  51  from the left side plate portion  33  is smaller than that of the right front plate portion  52  from the right side plate portion  34 . That is, the left and right front plate portions  51 ,  52  are bilaterally asymmetrical. The left and right side plate portions  33 ,  34  are arranged laterally side by side at a distance from each other on a side to the left of a lateral center of a tube portion  31 . 
     A part of a lower end part of the left front plate portion  51  and a part of a lower end part of the right front plate portion  52  are disposed in an opening region of a fixed-diameter hole portion  21  of a detection hole  20 . The fixed-diameter hole portion  21  of the detection hole  20  is facing a region of the left front plate portion  51  including a lower end part of a base end part  47  connected to the left side plate portion  33 . In the opening region of the fixed-diameter hole portion  21 , an area occupied by the left front plate portion  51  is larger than that occupied by the right front plate portion  52 . However, the extension dimension of the left front plate portion  51  from the left side plate portion  33  is smaller than in the first embodiment. Therefore, the left front plate portion  51  is less likely to be deformed rearward when the detection pin P pushes the left front plate portion  51 . 
     Third Embodiment 
     A third specific embodiment of the present disclosure is described with reference to  FIG. 7 . The third embodiment is different from the first embodiment in the configuration of a left front plate portion  56  of a terminal fitting  55 . Since the other components are the same as in the first embodiment, the same components are denoted by the same reference signs and structures, functions and effects thereof are not described. 
     The terminal fitting  55  of the third embodiment includes only one front plate portion  56 . The front plate portion  56  is cantilevered rightward at a right angle to a left side plate portion  33  from the front end edge of the left side plate portion  33 . An extending end edge part (right end edge part) of the front plate portion  56  is proximately facing the front end edge of a right side plate portion  34  from front or in contact with the front end edge of the right side plate portion  34  to cover the front end edge of the right side plate portion  34  from front. The front plate portion  56  is supported on a tube portion  31  at two positions on a base end part  57  (left end edge part) and the extending end part (right end edge part). Therefore, even if a detection pin P pushes the front plate portion  56  rearward, there is no possibility that the front plate portion  56  is deformed rearward. 
     Fourth Embodiment 
     A fourth specific embodiment of the present disclosure is described with reference to  FIG. 8 . The fourth embodiment is different from the first embodiment in the configurations of a left front plate portion  61  (plate-like portion as claimed) and a right front plate portion  62  of a terminal fitting  60 . Since the other components are the same as in the first embodiment, the same components are denoted by the same reference signs and structures, functions and effects thereof are not described. 
     The left front plate portion  61  is cantilevered rightward at a right angle to a left side plate portion  33  from the front end edge of the left side plate portion  33 . The right front plate portion  62  is cantilevered leftward at a right angle to a right side plate portion  34  from the front end edge of the right side plate portion  34 . An extension dimension of the left front plate portion  61  from the left side plate portion  33  is larger than half the width of a tube portion  31 . An extension dimension of the right front plate portion  62  from the right side plate portion  34  is also larger than half the width of the tube portion  31 . 
     The left front plate portion  61  is formed with a fitting recess  63  having a lying T shape in a front view. The right front plate portion  62  is formed with a fitting projection  64  having a lying T shape in the front view. Since the fitting recess  63  and the fitting projection  64  are fit to each other, relative displacements of the left and right front plate portions  61 ,  62  in the vertical direction and lateral direction are restricted. 
     A part of a lower end part of the left front plate portion  61 , a part of a lower end part of the right front plate portion  62  and a part of the fitting projection  64  are disposed in an opening region of a fixed-diameter hole portion  21  of a detection hole  20 . The fixed-diameter hole portion  21  of the detection hole  20  is facing a region of the left front plate portion  61  including a lower end part of a base end part  65  connected to the left side plate portion  33 . In the opening region of the fixed-diameter hole portion  21 , an area occupied by the left front plate portion  61  is larger than that occupied by the right front plate portion  62 . 
     Other Embodiments 
     The present invention is not limited to the above described and illustrated embodiments and is represented by claims. The present invention is intended to include all changes in the scope of claims and in the meaning and scope of equivalents and also include the following embodiments. 
     Although the detection pin is facing the part of the front plate portion eccentric toward the plate-like portion from the center of the tube portion in the front view in the above first to fourth embodiments, the detection hole may be facing a part of the front plate portion located in the center of the tube portion in the front view. 
     Although the resilient contact piece is folded to extend from the base plate portion and the front plate portion extends from the plate-like portion different from the base plate portion in the above first to fourth embodiments, the front plate portion may extend from the base plate portion. 
     Although the detection hole is facing the region of the front plate portion including the base end part connected to the plate-like portion in the above first to fourth embodiments, the detection hole may be facing only a region of the front plate portion deviated from the base end part. 
     Although the front plate portion covers at least a part of the resilient contact piece from front in the above first to fourth embodiments, the front plate portion may not cover the resilient contact piece from front. 
     Although the rear end of the detection hole is open to face the region of the terminal fitting where the front plate portion is not formed in the above first to fourth embodiments, the rear end of the detection hole may be open to face only the front plate portion without facing the region of the terminal fitting where the front plate portion is not formed. 
     Although the guide slope is formed on the inner periphery of the detection hole in the above first to fourth embodiments, the guide slope may not be formed. 
     Although the guide slope is formed only in the region of the detection hole on the rear end side in the above first to fourth embodiments, the guide slope may be formed over an entire region from the front end to the rear end of the detection hole or may be formed only in a region of the detection hole on the front end side. 
     Although the guide slope is formed by recessing the inner surface of the terminal accommodation chamber in the above first to fourth embodiments, the guide slope may be formed only in a region forward of the front end of the terminal accommodation chamber without recessing the inner surface of the terminal accommodation chamber. 
     Although the tube portion is in the form of a rectangular tube with four flat plate portions in the above first to fourth embodiments, the tube portion may be shaped to have curved plate portions. 
     LIST OF REFERENCE NUMERALS 
     
         
           10 : housing 
           11 : housing body 
           12 : retainer 
           13 : terminal accommodation chamber 
           14 : bottom surface (inner surface) 
           15 : bottom wall portion 
           16 : locking lance 
           17 : retaining portion 
           18 : front wall portion 
           19 : tab insertion hole 
           20 : detection hole 
           21 : fixed-diameter hole portion 
           22 : guiding portion 
           23 : guide hole portion 
           24 : guide slope 
           30 ,  50 ,  55 ,  60 : terminal fitting 
           31 : tube portion 
           32 : base plate portion 
           33 : left side plate portion 
           34 : right side plate portion 
           35 : upper plate portion 
           36 : projection 
           37 : crimping portion 
           38 : wire 
           40 : resilient contact piece 
           41 : folded portion 
           42 : curved portion 
           43 : contact point portion 
           44 ,  51 ,  61 : left front plate portion (front plate portion) 
           45 ,  52 ,  62 : right front plate portion 
           46 : protrusion 
           47 ,  57 : base end part of left front plate portion 
           56 : front plate portion 
           63 : fitting recess 
           64 : fitting projection 
           65 : base end part of left front plate portion 
         P: detection pin 
         S: clearance 
         T: tab