Patent Publication Number: US-6702627-B2

Title: Connector and a method of assembling it

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a connector and to a method of assembling it. 
     2. Description of the Related Art 
     A side-retainer connector has a housing with a plurality of parallel cavities for receiving terminal fittings. A retainer mount hole is formed in one side surface of the housing and extends substantially normal to the cavities. A retainer can be pushed into the hole to lock the terminal fittings in the cavities. 
     Side-retainer connectors provide secure locking because the retainer is aligned substantially normal to the inserting direction of the terminal fittings. However, connectors of this type still have room for improvement. 
     For example, clearances are set between the retainer mount hole and the retainer, including a dimension along the inserting direction of the terminal fittings. These clearances are necessary to push the retainer smoothly. However, a retainer mount position may vary forward or backward along the inserting direction of the terminal fittings due to such clearances. 
     Similar clearances are set between the retainer and the retainer mount hole and permit the retainer to tilt. A retainer that tilts backward while at a most forward position in the mount hole may interfere with the terminal fittings even though the terminal fittings are inserted to a proper depth. Thus, an insufficiently inserted state of the terminal fittings may be detected erroneously. 
     Conversely, a retainer that tilts forward while at a rearmost position in the retainer mount hole may not interfere with the terminal fittings even though the terminal fittings are inserted insufficiently: In such a case, the insufficiently terminal fittings may not be detected. 
     The present invention was developed in view of the above problem and an object thereof is to detect the inserted states of terminal fittings. 
     SUMMARY OF THE INVENTION 
     The invention relates to a connector with a housing that is connectable with a mating connector housing. The housing has at least one cavity and a terminal fitting is insertable in the cavity along an inserting direction. The cavity may be parallel to the connecting direction of the housing and mating housing. A retainer mount hole is formed in the housing and communicates with the cavity. The mount hole is formed at an intermediate longitudinal position of the housing and opens to three sides. A retainer can be pushed into the mount hole to engage and lock the terminal fitting. The retainer and/or the housing has guide means for guiding the retainer oblique to the inserting direction of the terminal fitting and for pushing the terminal fitting to the proper depth. 
     A lock in the cavity can lock a terminal fitting that has been inserted to the proper depth. The lock preferably is resiliently deformable and cooperates with the retainer to achieve double locking. 
     The retainer is displaced from an initial position at a rear side of the retainer mount hole to a final mount position at the front side of the retainer mount hole along the inserting direction of the terminal fitting. 
     A terminal fitting may be inserted only lightly and therefore may be distanced from its proper depth. Such a terminal fitting immediately interferes with the retainer when an attempt is made to move the retainer from its initial position. Thus, the insufficiently inserted state can be detected. However, a terminal fitting may be only slightly before the proper depth. In this situation, the retainer pushes the terminal fitting and guides the terminal fitting to the proper depth as the retainer is moved obliquely from the initially position. The retainer then locks the terminal fitting in a proper state. 
     The guide for guiding the retainer obliquely to the inserting direction of the terminal fitting may be on the portion of the retainer held in sliding contact with the housing when the retainer is pushed into the retainer mount hole. 
     The retainer is movable forward and back in the retainer mount hole. Therefore, the function of the retainer to detect insufficient insertion is not hindered by a variation in the fitted position of the retainer unlike the prior art. 
     The retainer preferably comprises two opposed side plates that face opposite side surfaces of the housing. Guides are provided along a pushing direction of the retainer where the side plates and the housing face each other. The guides enable the retainer to be mounted in a proper posture and pushed without being inclined. 
     The retainer mount hole preferably is formed by cutting off the housing in an area extending from a surface that substantially faces the pushing direction of the retainer over to side surfaces substantially normal to and adjacent the surface that faces the pushing direction. However, the sides of the retainer substantially close openings in the opposite side surfaces of the housing made by the retainer mount hole. As a result, the sides of the retainer also serve as the outer walls of the housing, and the housing can be narrower than a housing that does not have a retainer mount hole in both side surfaces. 
     The retainer preferably is mounted in the housing for movement between partial and full locking positions. Insertion and withdrawal of the terminal fittings are permitted when the retainer is in the partial locking position. However, the retainer engages and locks the terminal fitting when the retainer is moved to the full locking position. A clearance preferably is defined between the retainer and the retainer mount hole so that an inserted state of the terminal fitting into the cavity can be seen through the clearance when the retainer is at the partial locking position. However, the retainer substantially closes the clearance when the retainer reaches the full locking position so that external matter cannot enter into the housing. 
     The retainer may comprise two spaced apart side plates. Additionally, either one of the facing surfaces of the side plates and the housing are formed with guide grooves that extend oblique to the inserting direction of the terminal fitting. The other of the side plates and the housing are formed with locking projections that align with the guide grooves and move along the extending direction of the guide grooves. Thus, the retainer is pushed in the oblique pushing direction and can be guided by the displacement of the locking projections in the guide grooves. 
     The cavities may be arranged at a plurality of stages in the housing and may be adapted to accommodate the terminal fittings inserted from behind. 
     The retainer can be moved longitudinally forward and backward in the retainer mount hole. Thus, a variation in the fitted position of the retainer does not hinder the ability of the retainer to detect the insufficiently inserted terminal fittings, and the insufficiently inserted terminal fitting can be corrected automatically. As a result, it is not necessary to reinsert the terminal fitting. 
     The locks may comprise ribs that can be held substantially in sliding contact with edges of the guide grooves. Locking means are provided at the surfaces of the side plates and those of the housing for engaging each other when the retainer is at a position for locking the terminal fittings. 
     A push-preventing projection may be provided at the rear of each locking projection with respect to the pushing direction of the retainer. Each locking projection may engage one end of the corresponding guide groove and the push-preventing projection may engage the other end of the corresponding guide groove when the retainer is at the partial locking position. Additionally, each locking projection preferably engages the other end of the corresponding guide groove and the push-preventing projection is disengaged from the guide groove and outside the retainer when the retainer is in the full locking position. Accordingly, a return movement of the retainer can be prevented by the locking projections and an inadvertent movement of the retainer to the full locking position can be prevented by the push-preventing projections. 
     The invention also relates to a method of assembling a connector. The method comprises inserting a terminal fitting along an inserting direction and into a cavity of a connector housing. The method then comprises pushing a retainer into a mount hole of the housing to engage and lock the terminal fitting in the housing. The pushing step includes guiding the retainer obliquely to the inserting direction of the terminal fitting, and thereby pushing an insufficiently inserted terminal fitting to the proper depth in the cavity. The retainer mount hole is at an intermediate longitudinal position of the housing and is open to three sides. The pushing step includes closing at least parts of the mount hole by the retainer as the retainer is pushed into the mount hole. 
     These and other objects, features and advantages of the present invention will become more apparent upon reading of the following detailed description of preferred embodiments and accompanying drawings. It should be understood that even though embodiments are separately described, single features thereof may be combined to additional embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a section showing a stare before a terminal fitting is inserted with a retainer partly locked. 
     FIG. 2 is a side view of a connector housing. 
     FIG. 3 is a front view of the connector housing. 
     FIG. 4 is a bottom view of the connector housing. 
     FIG. 5 is a front view of a retainer. 
     FIG. 6 is a side view of the retainer. 
     FIG. 7 is an enlarged section showing an essential portion of the partly locked retainer. 
     FIG. 8 is an enlarged section showing an essential portion of the fully locked retainer. 
     FIG. 9 is a section showing a state where the terminal fitting is inserted with the retainer partly locked. 
     FIG. 10 is a side view of a connector with the retainer partly locked. 
     FIG. 11 is a section of the connector with the retainer fully locked. 
     FIG. 12 is a side view of the connector with the retainer fully locked. 
     FIG. 13 is an enlarged view showing an essential portion of an engaged state of a side plate  12  and a mount groove. 
     FIGS.  14 (A) and  14 (B) are sections diagrammatically showing how the connector housings and the retainer are molded. 
     FIG. 15 is a front view of a connector housing. 
     FIG. 16 is section of the connector housing. 
     FIG. 17 is a rear view of the connector housing. 
     FIG. 18 is bottom view of the connector housing. 
     FIG. 19 is a side view of a retainer. 
     FIG. 20 is a front view in section of the retainer. 
     FIG. 21 is a front view of a connector when the retainer is partly locked. 
     FIG. 22 is a section of the connector when the retainer is partly locked. 
     FIG. 23 is a front view of a connector when the retainer is fully locked. 
     FIG. 24 is a section of the connector when the retainer is fully locked. 
     FIG. 25 is a perspective view enlargedly showing portions of the connector near a locking projection and a guide groove. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A connector according to the subject invention includes a housing identified by the numeral  1  in FIG.  1 . The housing  1  is formed of a synthetic resin and has an upper surface with a resiliently deformable lock arm  2 . The lock arm  2  is supported at one end and is engageable with an unillustrated mating housing to lock the two housings in a connected state. 
     Cavities  3  are provided at upper and lower stages inside the housing  1  and penetrate the housing  1  longitudinally along forward and backward directions. Terminal fittings  4  can be inserted from behind into the respective cavities  3 , and locks  5  are provided at the front sides of the bottom surfaces of the respective cavities  3  for partly locking the terminal fittings  4 . Each lock  5  extends substantially along the inserting direction ID of the terminal fitting  4  and has both front and rear ends supported. A lock projection  6  is formed on the upper surface of each lock  5 . The terminal fitting  4  has a box  4 A and a locking projection  4 B projects from the box  4 A. The locking projection  4 B of the terminal fitting  4  pushes the lock projection  6  as the terminal fitting  4  is inserted into the cavity  3  and hence deforms the lock  5  down. The locking projection  4 B eventually passes the lock projection  6 , and the lock  5  is restored resiliently so that the lock projection  6  engages the locking projection  4 B. 
     A synthetic resin retainer  7  is mountable in a retainer mount hole  8  in a bottom of the housing  1  substantially opposite the lock arm  2  and at an intermediate longitudinal position of the housing  1 . The terms top and bottom, as used herein, are to provide a frame of reference and do not imply a required gravitational orientation. The retainer mount hole  8  is formed by cutting away an area of the housing  1  including areas of the bottom surface and side surfaces of the housing  1 . Accordingly, the retainer mount hole  8  is open at three sides, i.e. the bottom side and the opposite lateral sides of the housing  1  and divides the respective upper and lower cavities  3  into front and rear sections and substantially exposes them to outside. 
     The retainer mount hole  8  has a slanted rear surface  9  and a vertical front surface  10 . The slanted rear surface  9  is sloped forward along the inserting direction ID of the terminal fittings  4 , while the vertical front surface  10  is aligned substantially normal to the inserting direction ID. 
     The retainer  7 , as shown most clearly in FIGS. 5 and 6, has a main body  11  and side plates  12  at opposite ends of the main body  11 . The main body  11  can be aligned with and fit in the retainer mount hole  8 . The main body  11  is substantially lattice-shaped and has windows  13  that are alignable with the respective cavities  3  at the lower stage when the retainer  7  is at a partial locking position in the housing  1  (see FIG.  1 ). A slanted surface  14  is defined at the rear of the main body  11  and has an inclination that substantially conforms to the slanted surface  9  of the retainer mount hole  8 . Locking projections  15  project at the bottom ends of the respective windows  13  of the main body  11  and also at positions on the upper surface of the main body  11  for engaging the terminal fittings  4 . 
     The side plates  12  are spaced from one another by a distance that substantially corresponds to the spacing between the opposite side surfaces of the housing  1 . The side plates  12  are larger than side openings made in the side surfaces of the connector housing  1  by the retainer mount hole  8 . Thus, the side plates  12  substantially close the corresponding side openings of the retainer mount hole  8  and project out from the edges of the side openings of the retainer mount hole  8  regardless of whether the retainer  7  is at the partial locking position or at the full locking position. Accordingly, the side plates  12  also serve as outer sidewalls of the housing  1 . 
     A substantially rectangular recess  16  is formed at the inner surface of each side plate  12  above the main body  11 , and a locking edge  17  is defined at the upper edge of the recess  16 . The locking edges  17  can hold the retainer  7  at the partial and full locking positions in the housing  1  as follows (see FIGS.  7  and  8 ). Specifically, a partial locking projection  18  and a full locking projection  19  are located one over the other above each side opening of the retainer mount hole  8  in the connector housing  1 , as shown in FIGS. 7,  8 ,  10  and  12 . However, the full locking projections  19  are wider than the partial locking projections  18 . The front edges of the partial locking projections  18  contact the front edges of the recesses  16  (see FIG. 10) when the retainer  7  is at the partial locking position, and thus restrict a backward movement in a direction opposite to the pushing direction PD of the retainer  7 . Further, the rear edges of the full locking projections  19  contact the rear edges of the recesses  16  (see FIG. 12) when the retainer  7  is moved to the full locking position to restrict a forward movement of the retainer  7  in the pushing direction PD. 
     The locking edges  17  of the retainer  7  can engage the partial locking projections  18  on the housing  1  to hold the retainer  7  at the partial locking position shown in FIG.  7 . In this position, the locking projections  15  of the retainer  7  are outside the cavities  3 , and the terminal fittings  4  can pass through the windows  13  in both inserting and withdrawing directions ID. Alternatively, the locking edges  17  can engage the full locking projections  19  to hold the retainer  7  in the full locking position shown in FIG.  8 . In this position, the locking projections  15  enter the cavities  3  and engage the rear ends of the boxes  4 A of the terminal fittings  4 . Accordingly, the retainer  7  and the locks  5  cooperate for doubly locking the terminal fittings  4  in the cavities  3 . 
     Guiding surfaces  22  to  25  are formed on the front and rear edges of each side plate  12  to guide the retainer  7  along the pushing direction PD and oblique to the inserting direction ID of the terminal fittings  4  into the housing  1 . Specifically, the front edge of each side plate  12  extends substantially normal to the inserting direction ID, and projections  20 ,  21  are formed at upper and lower positions on the front edge. Upper and lower front guide surface  22  and  23  are formed on the bottoms of the respective upper and lower projections  20 ,  21  and slope forwardly. Lower and upper rear guide surfaces  24  and  25  are formed along the rear edge of each side plate  12 . A slanted surface  26  is formed on a stepped projection  27  continuous with and above the lower rear guide surface  24 . An upright surface  28  extends from the stepped projection  27  to the upper rear guide surface  25  and a vertical edge extends up from upper rear guide surface  25  substantially normal to the inserting direction ID. 
     The guide surfaces  22  to  25  and the slanted surface  26  of the stepped projection  27  all have an inclination substantially equal to the inclination of the slanted surface  9  of the retainer mount hole  8 . Thus, the guide and slanted surfaces  22 - 26  guide movements of the retainer  7  between the partial and full locking positions. Specifically, front guides  29  project from portions of the outer side surfaces of the housing  1  that face the front edges of the side plates  12 . A fittable recess  30  is formed in the rear edge of each front guide  29  and has a shape that substantially conforms to the outer shape of the lower projection  21 . Accordingly, the fittable recess  30  is engageable with the lower projection  21  when the retainer  7  reaches the full locking position. A receiving edge  31  is formed at the bottom end of each front guide  29 . The receiving edges  31  slide in contact the lower front guide surfaces  23  of the retainer  7  and guide the retainer  7  as the retainer  7  is pushed to the full locking position. During this time, the rear-upper corner portions of the front guides  29  are held in sliding contact with the upper front guide surfaces  22  (see FIG.  10 ). 
     Rear lower guides  32  project at the outer side surfaces of the housing  1  behind the side openings of the retainer mount hole  8 , and the front bottom ends thereof are held in sliding contact with the lower rear guide surfaces  24  of the retainer  7  when the retainer  7  is moved from the partial locking position to the full locking position. Rear middle guides  33  project above the rear lower guides  32  at the side surfaces of the housing  1 , and front bottom corners thereof are cut off for sliding contact with the upper rear guide surfaces  25  of the retainer  7 . 
     The front and rear edges of each side plate  12  of the retainer  7  are beveled over the entire height and taper toward the outer side. On the other hand, dovetail grooves  29 A,  32 A,  33 A,  34 A are formed at portions of the front guide  29 , the rear lower guide  32 , the rear middle guide  33  and an upper projection  34  that face the corresponding side plate  12 . The beveled edges of the side plates  12  slide in the dovetail grooves  29 A,  32 A,  33 A,  34 A to prevent the side plates  12  from opening wider. 
     A specified clearance “P” exists between the front end of the retainer  7  and the front end of the retainer mount hole  8  when the retainer  7  is at the partial locking position of FIG.  1 . The inserted states of the terminal fittings  4  can be seen through the clearance from outside the housing  1 . 
     The terminal fittings  4  are inserted into the respective cavities  3  with the retainer  7  at the partial locking position, as shown in FIGS. 1 and 10. The locking projection  4 B of the terminal fitting  4  pushes the lock projection  6  of the lock  5  during the insertion process and deforms the lock  5 . However, the lock  5  is restored resiliently after the locking projection  4 B passes the locking projection  6  and the locking projection  6  engages the locking projection  4 B for partial locking. The specified clearance P exists between the front end of the retainer  7  and the front end of the retainer mount hole  8  when the retainer  7  is at the partial locking position, and the insides of the cavities  3  can be seen through the clearance P. Thus, a visual inspection can determine that the terminal fittings  4  have been inserted. 
     The main body  11  of the retainer  7  then is pushed to move the retainer  7  in the pushing direction PD and into the retainer mount hole  8 . The pushing direction is oblique to the inserting direction ID so that the retainer  7  has a movement component in the inserting direction ID. The locking edges  17  move beyond the partial locking projections  18  and engage the full locking projections  19  to hold the retainer  7  at the full locking position. The locking projections  15  of the retainer  7  enter the corresponding cavities  3  when the retainer  7  reaches the full locking position to engage the rear ends of the boxes  4 A of the terminal fittings  4 . Thus, the locks  5  and the retainer  7  doubly lock the terminal fittings  4 . At this stage, the retainer  7  closes the opening of the mount hole  8  formed in the bottom surface of the housing  1  to prevent dust and the like from entering the cavities  3 . 
     The retainer  7  moves obliquely forward between the partial and full locking positions and is guided by sliding contact of the lower front guide surfaces  23  with the receiving edges  31 , sliding contact of the upper front guide surfaces  22  with the upper corners of the front guides  29 , sliding contact of the lower rear guide surfaces  24  with the front bottom ends of the rear lower guides  32  and sliding contact of the upper rear guide surfaces  25  and the front corners of the rear middle guides  33 . Accordingly, the oblique movement of the retainer  7  in the pushing direction PD causes the locking projection  15  to push the rear end of the box  4 A of any terminal fitting  4  that had been inserted insufficiently. Thus, any terminal fitting  5  left insufficiently inserted is pushed automatically to its proper position. 
     The retainer  7  interferes with the box  4 A of a terminal fitting  4  that is not inserted sufficiently to be pushed into the fully inserted position. Thus, an operator can detect the insufficiently inserted state of the terminal fitting  4 . 
     As described above, the retainer  7  moves forward in the retainer mount hole  8  as the retainer  7  is moved from the partial to full locking positions. Additionally, the retainer  7  is guided to a specified position at the front of the retainer mount hole  8  regardless of a variation in the fitted position of the retainer  7 . Additionally, the retainer  7  is supported on the housing  1  by the guide surfaces  22  to  25  at the front, rear and upper and lower sides while being moved from the partial locking position to the full locking position and can be pushed in a stable posture without being inclined or misaligned. Therefore, the mounted retainer  7  and the terminal fittings  4  are engaged with a proper positional relationship and a function of detecting the inserted states of the terminal fittings  4  is displayed efficiently. 
     The front and rear edges of the opposite side plates  12  engage the dovetail grooves  29 A,  32 A,  33 A,  34 A in the guides  29 ,  32 ,  33 ,  34  to prevent the side plates  12  from opening away from the housing  1  while the retainer  7  is moved from the partial locking position to the full locking position. Thus, the retainer  7  can be moved smoothly and securely by the guide surfaces  22  to  25 . The retainer mount hole  8  is open in the side surfaces of the housing  1 , and the side plates  12  of the mounted retainer  7  close the side openings. In other words, the side plates  12  of the retainer  7  serve as the outer walls of the sides of the housing  1 , and the connector can be narrower than a connector in which the retainer mount hole  8  is not open in the side surfaces and the side plates  12  of the retainer  7  are placed on the side surfaces of the housing  1 . 
     The retainer  7  and the housing  1  can be molded in the same mold, and the retainer  7  can be mounted at the partial locking position in the mold. 
     As described above, the retainer mount hole  8  is open in the opposite side surfaces of the housing  1 . As shown in FIGS.  14 (A) and  14 (B), the entire housing  1  is formed by a pair of molds  35 ,  36  that open and close along the longitudinal direction of the cavities  3 , and the retainer mount hole  8  is formed by a slidable mold  37  advanced and retracted substantially normal to the planes of FIGS.  14 (A),  14 (B). Further, the retainer  7  is formed in the same molds  35 ,  36  for the housing  1 . The retainer  7  can be pushed toward the retainer mount hole  8  by a pushing pin  38  after the molds  35 ,  36  are opened, and can be mounted at its partial locking position. In other words, the connector can be assembled in the molds. 
     The retainer mount hole  8  has the side openings in the housing  1 . Thus, a retainer forming portion cannot be provided in a movable area of the molds for forming the retainer mount hole  8 . Accordingly, it is necessary to form the retainer  7  outside this movable area. The retainer then is moved to a position where it faces the opening of the retainer mount hole  8  after the molds  35 ,  36  for forming the retainer mount hole  8  are opened. This results in a complicated mold structure. In this respect, the connector of this embodiment can be assembled up to the mounting of the retainer  7  from this position in the molds having a simple structure. 
     A connector according to a second embodiment is illustrated in FIGS. 15 to  25 , and includes a housing  1  unitarily formed from a synthetic resin. A resiliently deformable lock arm  2  is cantilevered from the middle of the upper surface of the housing  1 . The lock arm  2  is engageable with an unillustrated mating connector housing to lock the housings together. 
     Cavities  3  are arranged along the widthwise direction at upper and lower stages inside the housing  1 . The cavities  3  penetrate the housing  1  along forward and backward directions, and terminal fittings  125  can be moved along the inserting direction ID for insertion from behind into the cavities  3 . Locks  5  are at the front sides of the bottom surfaces of the cavities  3  for partly locking the terminal fittings  125 . Each lock  5  extends forward along the inserting direction ID and is supported at only one end. Thus, each lock  5  is resiliently deformabley vertically substantially normal to the inserting direction ID. The lock  5  is deformed down as the terminal fitting  125  is inserted. After sufficient insertion, the lock  5  is restored resiliently so that the front end of the lock  5  engages a locking projection  127  formed on the terminal fitting  125  to prevent the terminal fitting  125  from coming out. A projection-inserting groove  16  extends along forward and backward directions substantially in the middle of the upper surface of each lock  5 , thereby reducing a degree of downward resilient deformation of the lock  5  during the passage of the terminal fitting  125 . Thus, the entire connector can be shorter by reducing the clearances between the locks  5  and the bottom surfaces of the cavities  3 . 
     The terminal fitting  125  is formed by bending, folding and/or embossing a metal plate stamped or cut into a specified shape. A box-shaped main portion  126  is formed at the front of the terminal fitting  125  and is connectable with a tab of a mating male terminal fitting. A barrel  130  is formed at the rear end of the terminal fitting  125  for connection with a wire  131 . A front end of the bottom surface of the main portion  126  is embossed or cut and bent at a middle position to form the locking projection  127 . A rear end of the surface with the locking projection  127  also is embossed or cut and bent substantially in the middle to form a projection  128 . A stabilizer  129  extends at the side of the projection  128  and can be moved forward in an escaping groove  104  at one corner of the bottom surface of each cavity  3 . The stabilizer  129  does not align with the escaping groove  104  when the terminal fitting  125  is inserted in an improper orientation. Thus improper insertion of the terminal fitting  125  can be prevented. 
     A retainer mount hole  110  is formed in the surface of the housing  1  opposite from the lock arm  2  and in the adjacent side surfaces. Accordingly, the retainer mount hole  110  is provided at an intermediate longitudinal position of the connector housing  1  and is open at three sides. Further, the retainer mount hole  110  has a depth sufficient to expose the cavities  3  at the upper stage so that the upper and lower cavities  3  are divided into front and rear sections. The opening edges of the respective cavities  3  all extend substantially vertically or normal to the inserting direction ID at the front surface of the retainer mount hole  110 , but are inclined down to the back at an angle oblique with respect to the inserting direction ID of the terminal fittings  125  at the rear surface thereof. 
     A stepped surface  113  is recessed at an area of each side surface of the housing  1  above and behind the side opening of the retainer mount hole  110 . A rib-shaped locking projection  114  is formed on the stepped surface  113  and extends substantially along the inclined side of the side opening of the retainer mount hole  110 . A bevel  115  is formed entirely along the side of each locking projection  114  toward the retainer mount hole  110 . The upper and lower end surfaces of each locking projection  114  are formed into horizontal surfaces  116 , and a vertical surface  117  is substantially continuous with the upper horizontal surface  116 . 
     A push-preventing projection  118  is formed on a downward extension line from each locking projection  114 . 
     A shake-restricting portion  119  projects above the locking projection  114  on each stepped surface  113 . Each shake-restricting portion  119  extends substantially horizontally along forward and backward directions and has a cut-away portion  120  on the upper edge so that a rear part is slightly narrower. A slanted surface  123  is formed over the entire bottom edge of each shake-restricting portion  119  and a hooking piece  121  projects before each shake-restricting portion  119 . The hooking pieces  121  are formed such with upper edges that are substantially continuous with the upper edges of the corresponding shake-restricting portions  119 . Slanted surfaces  122  are formed at the front of the hooking pieces  121  and incline forward and up. 
     The connector further includes a retainer  135  made e.g. of a synthetic resin similar to the housing  1 , and is comprised of a main body  136  that is fittable into the retainer mount hole  110  and a pair of side plates  140  that bulge out at the opposite ends of the main body  136 . 
     The main body  136  is formed with windows  137  that align with the respective cavities  3  at the lower stage of the housing  1 . The front opening edges of the windows  137  extend vertically and align with the rear opening edges of the front sections of the respective cavities  3  divided by the retainer mount hole  110 , whereas the rear opening edges thereof are inclined to conform to the inclination of the front opening edges of the rear sections of the cavities  3 . Front parts and the upper surfaces of the main body  136  are at substantially the same height as the bottom surfaces of the corresponding cavities  3  when the retainer  135  is locked partly (FIG. 22) to permit insertion and withdrawal of the terminal fittings  125  in the inserting direction ID. However, rear parts of the bottom surfaces of the respective windows  137  are raised slightly. Front end surfaces  146 A of the bottom walls of the windows  137  and front end surfaces  146 B of the upper walls of the main body  136  are engageable with the projections  128  of the terminal fittings  125  when the retainer  135  is moved to the full locking position to lock the terminal fittings  125  doubly in cooperation with the locks  5 . 
     Stabilizer inserting grooves  139  are formed in the bottom surfaces of the windows  137  and the upper surface of the retainer main body  136  for permitting the passage of the stabilizers  129  of the terminal fittings  125 . However, the respective stabilizers  129  and the stabilizer inserting grooves  139  are displaced vertically from each other when the retainer  135  is moved to the full locking position. Thus, the rear end surfaces of the stabilizers  129  can engage the wall surface of the retainer  135  located below the front ends of the stabilizer inserting grooves  139 . 
     The opposite side plates  140  of the retainer  135  have a spacing corresponding to the space between the opposite side surfaces of the housing  1  and are deformable in opening directions away from the housing  1  to widen the spacing. Opposite side plates  140  are dimensioned to substantially close side openings of the retainer mount hole  110  and face specified areas of the corresponding stepped surfaces  113  when the retainer  135  is locked fully. The thickness of the side plates  140  substantially equals the depth of the stepped surface  114  from the outer side surfaces of the housing  1 , so that the side plates  140  are substantially flush with the corresponding outer surfaces of the housing  1  when the retainer  135  is locked fully. Thus, the side plates  140  of the retainer  135  also serve as the outer walls of the sides of the housing  1 . 
     A thick operable portion  141  extends outwardly on the outer surface of the rear part of each side plate  140 , and the bottom end thereof projects from the bottom surface of the retainer  135 . Further, each side plate  140  is formed with a guide groove  142  behind the main body  136 . Each guide groove  142  has substantially the same inclination as the rear opening edges of the respective windows  137  of the retainer  135 , i.e. the front opening edges of the rear sections of the respective cavities  3  of the connector housing  1 , and a bottom portion thereof is located in the operable portion  141 . The guide grooves  142  have a width substantially equal to the shorter width of the locking projections  114  as measured normal to the pushing direction PD, and the opposite ends of the guide grooves  142  are shaped to substantially conform to the shapes of the opposite ends of the locking projections  114 . The guide grooves  142  are engageable with both the locking projections  114  and the push-preventing projections  118  at their opposite ends to hold the retainer  135  at the partial locking position. The side plates  140  move onto the push-preventing projections  118  to bring the push-preventing projections  118  out of the guide grooves  142  while the retainer  135  is moved from the partial locking position to the full locking position. The side plates  140  are deformed in opening directions during this time. However, the projecting distance of the locking projections  114  is larger than that of the push-preventing projections  118  and is set at a value sufficient to keep the locking projections  114  engaged with the guide grooves  142  even if the side plates  140  are deformed to open wider. In this way, the retainer  135  reaches the fully locked state by moving the locking projections  114  toward the bottom ends of the guide grooves  142 . 
     A restricting recess  143  is formed in the inner surface of each guide plate  140  above the guide groove  142  and receives the corresponding shake-restricting portion  119 . Slanted surfaces  144  are formed on the upper and lower edges of the restricting recess  143 . The restricting recess  143  is substantially rectangular and extends from a substantially middle position of the side plate  140  to the rear end along the insertion direction ID. The restricting recess  143  also extends from the upper end of the guide groove  142  to the upper end of the side plate  140  along the height direction, which is substantially normal to the inserting direction ID. Upper edges of the shake-restricting portions  119  and those of the restricting recesses  143  are held at a height where they substantially align with each other when the retainer  135  is locked partly and a specified clearance is defined between the lower edges of the shake-restricting portions  119  and those of the restricting recesses  143 . The tapered surfaces  123  at the lower edges of the shake-restricting portions  119  substantially align with and contact the slanted surfaces  144  at the lower edges of the restricting recesses  143  when the retainer  135  is locked fully, thereby preventing the retainer  135  from making upward shaking movements. 
     The restricting recesses  143  extend further forward, and locking claws  145  are formed above these extended sections. The locking claws  145  are substantially at the same height as the hooking pieces  121  of the housing  1  and face the hooking pieces  121  when the retainer  135  is locked partly. However, the locking claws  145  move over the slanted surfaces  122  of the hooking pieces  121  to engage the upper edges of the hooking pieces  121  when the retainer  135  is locked fully, thereby holding the retainer  135  at the full locking position. 
     A specified clearance  147  is defined between the front end of the retainer  135  and the front end of the retainer mount hole  110  when the retainer  135  is locked partly. Thus, the inserted states of the terminal fittings  125  can be confirmed through the clearance  147  from outside of the housing  1 . 
     The retainer  135  preferably is transported to a site of connecting connectors while being mounted at the partial locking position in the housing  1 . The retainer  135  is mounted at the partial locking position by holding the opposite stepped surfaces  113  of the housing  1  from opposite sides by the side plates  140  of the retainer  135  while suitably opening the side plates  140 , and fitting the locking projections  114  and the push-preventing projections  118  into the guide grooves  142 . The locking projections  114  and the push-preventing projections  118  are engaged with the opposite ends of the guide grooves  142 . Thus, the retainer  135  is positioned at the partial locking position and is prevented from inadvertent movement to the full locking position. The shake-restricting portions  119  are located in the restricting recesses  143  of the retainer  135  at the partial locking position. However, the specified clearances are defined between the bottom edges of the shake-restricting portions  119  and those of the restricting recesses  143  in this state. 
     The bottom surfaces of the respective windows  137  of the retainer  135  and the upper surface of the main body  136  are substantially flush with the bottom surfaces of the respective cavities  3  at the upper and lower stages with the retainer  135  partly locked. Accordingly, the terminal fitting  125  passes the retainer  135 . The terminal fitting  125  then is pushed further into the cavity  3  along the insertion direction ID and contacts the lock  5  from behind. The locking projection  127  engages the projection-inserting groove  106  and causes the lock  5  to undergo a necessary and minimum deformation. Sufficient insertion causes the locking projection  127  to pass the lock  5 . Thus, the lock is restored resiliently and engages the front-end surface of the lock  5 . The specified clearance  147  is defined between the front end of the retainer  135  and the retainer mount hole  110  with the retainer  135  partly locked. As a result, the insides of the cavities  3  can be seen, and insertion of the terminal fittings  125  will not be forgotten. 
     Thereafter, the retainer  135  is pushed strongly by holding the operable portions  141 . Then, portions of the retainer  135  near the bottom ends of the guide grooves  142  are deformed to move onto the push-preventing projections  18  and bring them out of the guide grooves  142 , and the retainer  135  is pushed obliquely up in the pushing direction PD and is guided by the engagement of the locking projections  114  and the guide grooves  142 . The locking projections  114  are held in sliding contact with the guide grooves  142  over a specified length during this time. Therefore, the retainer  135  can be pushed in a stable posture without being inclined or tilted in a clockwise direction in FIG.  21 . 
     When the retainer  135  reaches the full locking position, the front end surfaces  146 A of the bottom walls of the windows  137  and the front end surfaces  146 B of the upper walls of the main body  136  are engageable with the projections  128  of the terminal fittings  125  to doubly lock the terminal fittings  125  in cooperation with the locks  5  inside the housing  1 . At the full locking position, the locking projections  114  engage the bottom ends of the guide grooves  142 , but the push-preventing projections  118  are located outside the operable portions  141 . The locking claws  145  move over the slanted surfaces  122  of the hooking pieces  121  and engage the upper edges of the hooking pieces  121  at this time. Consequently, the retainer  135  is locked at the full locking position. Further, the bottom edges of the shake-restricting portions  119  engaged the bottom edges of the restricting recesses  143 . Accordingly, the retainer  135  is prevented from making upward shaking movements. 
     The front surface of the retainer main body  136  substantially abuts the front surface of the retainer mount hole  110  when the retainer  135  reaches the fully locked state. Thus the retainer  135  substantially closes the retainer mount hole  110  without leaving any substantial clearance therebetween. Thus, dust and the like cannot enter into the cavities  3 . 
     The terminal fitting  125  could be inserted insufficiently and left unlocked by the lock  5 . This insufficiently inserted terminal fitting  125  can be brought automatically to the proper position because the retainer  135  pushes the projection  128  of the terminal fitting  125  during its oblique movement in the pushing direction PD. If the terminal fitting  125  inserted less than the above insufficiently inserted state, the retainer  135  interferes with the bottom surface of the main portion  126  of the terminal fitting  125  even if an attempt is made to push the retainer  135 . Thus, the retainer  135  cannot be pushed any further. Therefore, an operator can detect that the terminal fitting  125  is distant from its proper insertion position. 
     The terminal fittings  125  may need to be withdrawn for maintenance or other reason. Then, the retainer  135  needs to be returned to the partial locking position. In such a case, a disengagement jig can be inserted into clearances inside the inner surfaces of the side plates  140  of the retainer  135 , i.e. the clearance between the operable portions  141  and the cut-away portions  120  to forcibly open the side plates  140  wider. The retainer  135  then is moved back and obliquely downward in this state. When the push-preventing projections  18  are fitted into the guide grooves  142 , the retainer  135  can be returned to the partial locking position. The terminal fitting  125  can be withdrawn if the locking portion  5  is disengaged therefrom using another disengagement jig inserted from front of the connector housing  1  in this state. 
     As described above, according to this embodiment, the retainer  135  moves forward in the retainer mount hole  110  while being moved from the partial locking position to the full locking position. Thus, the retainer  135  can be guided to a specified position at the front end of the retainer mount hole  110  regardless of a variation in the fitted position of the retainer  135 . In addition, since the retainer  135  is guided by the engagement of the guide grooves  142  and the locking projections  114  while being moved from the partial locking position to the full locking position, it can be pushed stably and smoothly in the intended direction PD. Thus, the retainer  135  and the terminal fittings  125  are engaged in a proper positional relationship at the full locking position. Therefore, unlike the prior art, the function of the retainer  135  to detect the inserted states of the terminal fittings  125  can be fulfilled securely and the locked state can be obtained. 
     The retainer mount hole  110  is open in the side surfaces of the connector housing  1  in this embodiment. However, the side plates  140  close these side openings when the mounted retainer  135  reaches the full locking position. Thus, the side plates  140  of the retainer  135  also serve as the outer sidewalls of the housing  1  in this embodiment. Accordingly, the entire connector can narrower than connectors in which the retainer mount hole  110  is not open in the side surfaces and the side plates  140  of the retainer  135  are placed on the side surfaces of the housing  1 . 
     In this embodiment, the cavities  3  at the upper and lower stages in the connector are locked not by separate retainers prepared for the respective stages, but by one retainer at once. Thus, the number of parts and the number of operation steps can be reduced. 
     The invention is not limited to the above described and illustrated embodiment. For example, the following embodiments are also embraced by the technical scope of the present invention as defined by the claims. Beside the following embodiments, various changes can be made without departing from the scope and spirit of the present invention as defined by the claims. 
     Although the retainer mount hole has the side openings in the housing, it may be open only in the upper surface of the housing. 
     The guide surfaces are provided at the upper and lower sides of the front and rear edges of the side plates of the retainer in the first embodiment. However, they may be provided on only either front or rear edge or at only either upper or lower side. The guide surfaces need not be provided at the side edges of the side plates and may be at other positions as long as the retainer can be guided obliquely. 
     Although the guide grooves  42  are in the retainer  35  and the locking projections  14  are provided on the housing  1  in the second embodiment, a reverse arrangement may be adopted. 
     Although the retainer  35  takes the partly locked state in the second embodiment, it may be directly transferred to the fully locked state without setting the former state. 
     The hooks  121  and the locking claws  145  form the locking means for holding the retainer  135  fully locked in the second embodiment. The push-preventing projections are designed to contact the outer surfaces of the retainer when the retainer is locked fully, and the retainer can be locked by being tightly held between the locking projections and the push-preventing projections. 
     The guide grooves  142  may not necessarily be through-grooves, but may be bottomed grooves. Contrary to the second embodiment, the guide grooves may be formed in the connector housing and the locking projections may be provided on the retainer.