Abstract:
A structure for locking two workpieces includes: a first workpiece  1  provided with a provisional locking arm  3  and a complete locking arm  4  which are in parallel; a second workpiece  2  provided with an arm receiving portion  5  having a provisional engaging area  15  and a complete engaging area  12  which are to be engaged with the provisional locking portion and the complete locking portion, respectively and a pair of arm guiding portions  6  and  7  on both sides of the arm receiving portion, the arm receiving portion being to advance in between the provisional locking arm and the complete locking arm. One of the arm guiding portions is provided with a slope  21  for slidably supporting a tip of the complete locking arm when the complete locking arm climbs over the complete engaging portion. In such a configuration, inadvertent complete-locking or release thereof of two workpieces can be prevented.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a structure for locking provisionally and completely two workpieces such as a corrector housing and front holder. 
     2. Description of the Related Art 
     FIG. 8 shows an example of a conventional holder-equipped connector. A holder-equipped connector  51  includes a connector housing  52  of synthetic resin and a front holder  53  of synthetic resin that is inserted in the connector housing  52  from the front to form a terminal chamber  54 . 
     The connector housing  52  internally includes a holder inserting chamber  55 , a rear half  56  of the terminal chamber  54  which is successive to the inserting chamber  55  and a terminal locking lance  57  which projects into the holder inserting chamber  55 . The connector housing  52  is externally provided with a locking arm  58  corresponding to a complementary female connector (not shown). 
     The front holder  53  has an end wall, upper and lower walls and an intermediate partition wall. A hole  59  through which a male terminal (not shown) of a complementary male connector is formed in the end wall. In the specification, a connector having a connector chamber is defined as a female connector while another connector which is to be inserted into the connector chamber is defined as a male connector. 
     The front holder  53  is inserted into the connector housing  52  from its front, and fixed within the holder inserting chamber  55  by a fixing means (not shown). Subsequently, a wire-equipped terminal  60  is inserted into the terminal chamber  54 , and locked by a locking lance  57 . 
     Since the connector housing  52  and front holder  53  are formed as individual bodies, a complicate shape such as the locking lance  57  within the connector can be easily formed in a large scale. 
     Various formats have been proposed for locking the connector housing  52  and front holder  53  to each other. FIGS. 9 and 10 show a format of a locking structure for a holder-equipped connector. 
     In FIG. 9, reference numeral  61  denotes a connector housing and reference numeral  62  denotes a front holder. The connector housing  61  has an open space  63 . On the one inner wall thereof, a provisional locking projection  64  is formed, whereas on the other inner wall thereof, a complete locking projection  65  is formed. The provisional locking projection  64  and he complete locking projection  65  are formed in order from the entrance of the open space. The front holder  62  is equipped with a projecting arm  66  that approaches into the open space  63 . The arm  66  is equipped with a provisional locking projection  67  on the one side and a complete locking projection  68  on the other side. The arm  66  has a slit-like hole (hollow portion)  69  formed at its center so that the locking projections  67  and  68  can warp inwardly. 
     As seen from FIG. 9, when the provisional locking projection  67  of the front holder  62  has climbed over the provisional locking projection  64 , the complete locking projections  65  and  68  are brought into contact with each other so that the front holder  62  is provisionally locked to the connector housing  61 . The connector housing  61  and front holder  62 , while they are in the provisionally locked state, are transported to the subsequent step. 
     In the subsequent step, as shown in FIG. 10, the front holder  62  is completely pushed into the connector housing  61 . The complete locking projection  68  climbs over the complete locking projection  65  so that the rear end of the complete locking projection  68  is brought into contact with the rear end of the complete locking projection  68 , and an end face  70  on the bottom side of the front holder  62  is brought into contact with the front end face  71  of the connector housing  61 . Thus, the front holder  62  is completely locked to the connector housing  61 . In the specification, the direction of inserting the terminal and front holder  62  into the connector housing  61  is defined as “front”. 
     However, in the conventional locking structure of the holder-equipped connector, the pushing force required to secure the front holder  62  provisionally is substantially equal to that required to secure the front holder  62  completely. Owing to this, where the front holder  62  provisionally locked to the connector housing  61  is transported in e.g. an automated assembling machine, the front holder  62  may interfere with the outside so that the front holder  62  is inadvertently pushed in the connector housing  61 . In this case, an operator must release the complete locking using a jig bar or the like. This is very troublesome. 
     It is preferred that the provisional locking can be done easily and the complete locking can be done surely with the aid of great force. However, conventionally, the complete locking force of the front holder  62  is small so that the front holder  62  is apt to be inadvertently released owing to vibration while the vehicle runs. 
     In addition, since the slit-like holder (hollow portion) must be formed as the center in the width direction of the arm  66  of the front holder  62 , moldability of the arm is poor during resin molding of the front holder  62 . This requires a complicate mold and hence increases the production cost. 
     In other cases than locking of the front holder  62 , e.g. inserting a spacer for doubly locking a terminal in the connector or electric connection box, provisional locking means and complete locking means are required. In these cases also, the above problem occurs. 
     SUMMARY OF THE INVENTION 
     An object of this invention is to provide a structure for locking two workpieces which does not inadvertently secure completely two workpieces such as a front holder and a connector housing when they are locked to each other and can surely secure them completely with the aid of great force, and can be resin-molded easily and at low cost. 
     In order to attain the above object, in accordance with this invention, there is provided a structure for locking two workpieces comprising: 
     a first workpiece provided with a provisional locking arm and a complete locking arm which are in parallel; 
     a second workpiece provided with an arm receiving portion having a provisional engaging area and a complete engaging area which are to be engaged with the provisional locking arm and the complete locking arm, respectively and a pair of arm guiding portions on both sides of the arm receiving portion, the arm receiving portion being to advance in between the provisional locking arm and the complete locking arm, wherein one of the arm guiding portions is provided with a slope for slidably supporting a tip of the complete locking arm when the complete locking arm climbs over the complete engaging portion. 
     In the above configuration, the provisional locking arm is first engaged with the provisional engaging area of the arm receiving portion so that both workpieces are provisionally locked to each other. Next, as the first and/or the second workpiece are pushed in a combining direction, the complete locking arm warps outwardly while the complete locking arm climbs over the complete engaging area of the arm receiving portions and the outer area at the tip of the complete locking arm is brought into contact with the slope of the arm guiding portion so that the complete locking arm is supported in the sloped state on both ends. This increases the force required to warp the complete locking arm so that greater force is required for the complete locking than for he provisional locking. Thus, inadvertent shift from the provisional locking to the complete locking can be prevented. The complete locking arm climbs over the complete engaging area so that the former is engaged with the latter. Accordingly, both workpieces are completely locked to each other. When the complete locking is released, the outer area at the tip of the complete locking arm is in contact with the slope of the arm guiding portion so that the complete locking arm is supported on both ends. Therefore, greater force is required to release the complete locking than to release the provisional locking. Thus, inadvertent release of the complete locking can be prevented. Further, the pair of locking arms advance or retreat along the arm receiving portion and the arm guiding portions on the both sides thereof so that the pair of locking arms can be accurately positioned. This permits the provisional locking force and the complete locking force to be accurately specified. 
     In a preferred embodiment of this invention, the provisional locking arm has a provisional locking area at its tip, the complete locking arm has a complete locking area at its middle position in the longitudinal direction, the arm receiving portion has the provisional engaging area at its tip and the complete engaging area behind the provisional engaging area. 
     In the above configuration, when the provisional locking area of the provisional locking arm climbs over the provisional engaging area so as to be engaged with it, the complete locking area of the complete locking arm is brought into contact with the area of the arm receiving portion. This surely gives the provisional locked state with no backlash. 
     In a preferred embodiment, the provisional locking arm and the arm guiding portion have releasing slopes at their tips, respectively. 
     In the above configuration, when the provisional locking area of the provisional locking arm climbs over the provisional engaging area of the arm receiving portion so that the provisional locking arm warps outwardly, the slope of the outer area at the tip of the provisional locking arm passes smoothly along the slope of the inner area at the tip of the other arm guiding portion. Therefore, the provisional locking can be easily done with small force. 
     In a preferred embodiment of this invention, the provisional locking area and the complete locking area are formed as projections. 
     This configuration surely realizes the engagement between the provisional locking area and provisional engaging area in the provisional locking and the contact between the complete locking area and the complete engaging area. In addition, in the complete locking, the provisional locking portion smoothly moves straight along the arm receiving portion so that the complete locking area is surely engaged with the complete engaging area. 
     In a preferred embodiment of this invention, the first workpiece is a connector housing and the second workpiece is a front holder which defines a terminal chamber in the connector housing. 
     Owing to the above configuration, since the complete locking of the front holder to the connector housing is performed with greater force than the provisional locking thereof, the inadvertent pushing (complete locking) of the front holder and release thereof can be prevented. 
     The above and other objects and features of this invention will be more apparent from the following description taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of a locking structure of two workpieces according to this invention; 
     FIG. 2 is a plan view of the provisional state of the locking structure; 
     FIG. 3 is a plan view of the state on the way from the provisional locking to the complete locking in the structure; 
     FIG. 4 is a plan view of the complete locking state of the structure; 
     FIG. 5 is a longitudinal sectional view of an example of the holder-equipped connector to which the above locking structure of two workpieces is applied; 
     FIG. 6 is a front view of the connector housing; 
     FIG. 7 is a partially recessed perspective view of a front holder of the connector; 
     FIG. 8 is a longitudinal sectional view of a conventional holder-equipped connector; 
     FIG. 9 is a plan view of the provisional locking state of a conventional locking structure of two workpieces; and 
     FIG. 10 is a plan view of the complete locking of the conventional structure. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     Now referring to the drawings, a detailed description will be given of an embodiment of this invention. 
     FIGS. 1 to  4  show an embodiment of a structure for locking two workpieces according to this invention. 
     As seen from FIG. 1, this structure includes a provisional locking arm  3  and a complete locking arm  4  which constitute a pair of left and right resilient arms and are integral to an workpiece  1 , an arm receiving portion  5  which is attached to another workpiece  2  and adapted to approach in between the provisional locking arm  3  and the complete locking arm  4 , a first arm guide  6  which is a straight body attached to another workpiece  2  and located on the one side of the arm receiving portion  5  and a second arm guide  7  which is a sloped body attached to located on the other side of the arm receiving portion  6 . 
     The provisional locking arm  3  and complete locking arm  4  project straight and in parallel as cantilever beams with equal lengths. A provisional locking projection (provisional locking portion)  8  is formed integrally to the inside of the tip of the one provisional locking arm  3 , whereas a slope for releasing is formed integrally to the outside of the tip. 
     The provisional locking projection  8  is formed in a triangular shape to have a sloped face  8   a  (relatively gentle slope) sloping inwardly at an acute angle from the tip of the arm and a locking face  8   b  which crosses the internal face of the straight arm  3  with an obtuse angle at a short distance from the apex of the sloped face  8   a.  The sloped face  8   a  serves as a contact and sliding face for the arm receiving portion  5 . 
     The complete locking arm  4  has a complete locking protection (complete locking portion)  12  located at an intermediate position in the longitudinal direction of an beam-like arm body  12 . The complete locking projection  12  is formed integrally to the internal face of the arm body  11 . The complete locking projection  12  is located at a position slightly apart rearward from the provisional locking projection  8  in the longitudinal direction of the arm body  12 . The complete locking projection  12  has a trapezoidal shape composed of front and rear sloped faces  12   a,    12   b  and an intermediate straight face  12   c.  The front and rear slopes  12   a  and  12   b  cross the internal face of beam-like body  11  at an angle equal to that of the locking face  8   b  of the provisional locking projection  8 . The sloped face  19   a  serves as a contact and sliding face for the arm receiving portion  5 , whereas the rear sloped face  12   b  serves as a locking face. 
     A slit  13  is provided between the provisional locking projection  8  and the complete locking projection  12 . These projections inwardly protrude at approximately equal lengths. 
     The arm receiving portion  5  on the side of the other workpiece  2  is composed of a single straight rail- or pole-like receiving body  14 , a provisional engaging projection (provisional engaging portion)  15  and a complete engaging projection (complete engaging portion)  16 . These projections are formed integrally to the tip of the receiving body  14 . The provisional locking projection  15  is located as the tip of the arm receiving body  14  on the one side thereof so as to be opposite to the provisional locking projection (provisional locking portion)  8  of the provisional locking arm  3 . The complete engaging projection  16  is formed on the other side of the arm receiving body  14  so as to be opposite to the complete locking projection  12  of the complete locking arm  4 . The complete engaging projection  16  is located at a position slightly rearward or closer than the provisional engaging projection  15  to the bottom of the arm receiving portion  5 . 
     The provisional engaging projection  15  has a sloped face  15   a  at the tip of the receiving body, a straight face  15   c  successive to the sloped face  15   a  and a rear locking face  15   c  which is orthogonal to the one side of the receiving body  14 . The sloped face  15   a  is formed at a gradient which is more steep than that of the sloped face  8   a  of the provisional locking projection  8 , and can be brought into contact with the tip of the provisional locking arm  3  with relatively strong force. In this specification, the directions of fitting the workpieces  1  and  2  to each other are defined as “front”. 
     The complete engaging projection  16  has a first sloped face  16   a  which is relatively short and located on the tip of the receiving body  14 , a second sloped face  16   c  which is relatively long and extends to slope rearward from the first sloped face  16   a  and a locking face  16   b  which is orthogonal the other side of the receiving body  14  from the second sloped face  16   c.    
     These projections  15  and  16  outwardly protrude at approximately equal lengths. The first sloped face  16   a  of the complete engaging projection  16  and the intermediate portion in the longitudinal direction of the provisional engaging projection  15  are located on the same line in the width direction of the arm receiving portion  5 . The rear locking face  15   b  of the provisional engaging projection  15  and the intermediate portion in the longitudinal direction of the complete engaging projection  16  are located on the same line. The rear locking face  16   b  of the complete engaging projection  16  is located more slightly rearward than the locking face  15   b  of the provisional engaging projection  15 . 
     A first arm guide  6  and a second arm guide  7  are arranged outside the arm receiving portion  5 . The first arm guide  6  is located so as to be opposed to the one side of the arm receiving portion  5  on which the provisional engaging projection  15  is formed. The second arm guide  7  is located so as to be opposed to the other side of the arm receiving portion  5  on which the complete engaging projection  16  is formed. Both arm guides  6  and  7  are equal in length and slightly shorter than that of the arm receiving portion  5 . The tips of both arm guides  6  and  7  and the intermediate portion in the longitudinal direction of the provisional engaging projection  15  are located on the same line. The arm receiving portion  5  and both arm guides  6 ,  7  may be vertically projected from the horizontal wall  17  or the other workpiece  2 . Otherwise, they may be horizontally projected from the vertical base wall  18  of the other workpiece  2 . 
     The first arm guide  6  has a short tapered slope  19  inside its tip. The slope  19  is formed at the same gradient as that of the slope  9  outside the provisional locking arm  3  so that the outside slope  9  of the provisional locking arm  3  in an outwardly warped state can pass without being in contact with the slope  19 . The slope  19  of the arm guide  6  is successive to the straight inner face  20 . The inner face  20  is located slightly outside the outer face of the provisional locking arm  3  in a free state (non-warped state). The slope  19  of the arm guide  6  is located oppositely to the straight face  15   c  of the provisional engaging projection  15  and has a length approximately equal to that of the straight face  15   c.    
     The second arm guide  7  is located oppositely to the outer face of the arm receiving portion  5  on which the complete engaging projection  16  is formed. The second arm guide  7  has a long tapered slope  21  on its inside. The slope  21  extends from the tip of the arm guide  7  to the vicinity of the base thereof and the end thereof is successive to a short straight face  22 . The slope  21  is located outside the outer face of the complete locking arm  4  in a free state. The straight face  22  is located substantially flush with the outer face of the complete locking arm  4 . 
     In FIG. 1, where the other workpiece  2  is initially coupled with the one workpiece  1 , the provisional locking arm  3  warps outwardly while the provisional locking projection  8  at the tip of the provisional locking arm  3  is in contact with the provisional engaging projection  15  at the tip of the arm receiving portion  5  (the slopes  8   a  and  15   a  at the tips of the projections  8  and  15  are in a sliding contact with each other). While the slope  9  on the outer face of the provisional locking arm  3  passes along the slope  19  on the inner face at the tip of the of the first arm guide  6 , as shown in FIG. 2, the provisional locking projection  8  of the provisional locking arm  3  climbs over the provisional engaging projection  15  of the arm receiving portion  5 , and advances in between the first arm guide  6  and the guide receiving portion  5 . Thus, the locking faces  8   b  and  15   b  of both projections  8  and  15  are brought into contact with each other (FIG.  1 ). 
     Simultaneously, as seen from FIG. 2, the complete locking projection  12  of the complete locking arm  4  is brought into contact with the complete engaging projection  16  of the arm receiving portion  5 . Both projections  12  and  16  are in contact with each other in their front slopes  12   a  and  16   a.  The outer face at the tip of the provisional locking arm  3  is substantially brought into contact with the inner face of the first arm guide  6  whereas the outer face at the tip of the complete locking arm  4  is located apart by a gap  23  from the inner slope  21  of the second arm guide  7 . Since the provisional engaging projection  15  of the arm receiving portion  5  passes the provisional locking projection  8  of the provisional locking arm  3  and both projections  12  and  16  are brought into contact with each other, both workpieces  1  and  2  are provisionally locked to or coupled with each other. 
     Both workpieces  1  and  2  are further pushed into each other as shown in FIG. 3 from the provisional locked state of FIG. 2 in assembling directions. While the complete locking projection  12  climbs over the complete engaging projection  16  of the arm receiving portion  5 , the outer portion  11   a  at the tip of the complete locking arm  4  is brought into contact with the inner slope  21  of the second arm guide  7 . Thus, the complete arm  4  is supported at the front and rear terminals  11   a  and  11   b  so that it is changed from a cantilever beam into a normal beam (supported at both ends), thereby increasing the force required for warping the complete locking arm  4 . 
     Specifically, the complete locking arm  4  is initially supported at only the base  11   b  so that it is warped as a cantilever beam while both projections  12  and  16  are in contact with each other. Thereafter, the complete locking arm  4  is supported at the tip  11   b  by the slope  21  of the arm guide  7  so that it is warped outwardly as the normal beam at the longitudinal intermediate portion at fulcrums of the front and rear tips  11   a  and  11   b  by contact and sliding between both projections  12  and  16 , thereby increasing the warping force of the complete locking arm  4 . Thus, since the force required for the complete locking becomes larger than that required for the provisional locking. Therefore, the locking structure will not be inadvertently shifted from the provisional locking state into the complete locking state which it is transported. 
     As relative pushing between both workpieces  1  and  2  is advanced, the complete locking arm  4  is largely warped outwardly at the fulcrums of both tips  11   a  and  11   b.  As seen from FIG. 4, the complete locking projection  12  of the complete locking arm  4  climbs over the complete engaging projection  16  of the arm receiving portion  5  and advances toward the rear of the complete engaging projection  16 . Eventually, the locking faces  12   b  and  16   b  at the rear ends of both projections  12  and  16  are brought into contact with each other. While the complete locking arm  4  is restored straight, the outer face  11   a  at the tip of the complete locking arm  4  moves along the slope  21  of the arm guide  7  to reach the rear straight face  22  thereof. 
     The provisional locking arm  3  advances straight as it is along the first arm guide  6  from the state of FIG. 2 so that the provisional locking projection  8  of the provisional locking arm  3  advances along the outer face of the arm receiving portion  5 . The guide receiving portion  5  advances in between the pair or locking arms  3  and  4  and the provisional engaging projection  15  of the guide receiving portion  5  advances along the inner face of the provisional locking arm  3 . 
     Thus, the complete locking state of FIG. 4 results so that the other workpiece  2  is completely locked to the one workpiece  1 . Since the complete locking projection  12  is in contact with the complete engaging projection  16 , the other workpiece  2  is prevented from being taken off from the one workpiece  1 . For example, since the tips of both locking arms  3  and  4  are brought into contact with the base wall  18  of the other workpiece  2 , the other workpiece  2  is prevented from being further pushed. 
     Where the force of releasing the completely locked stale of FIG. 4 is acted on both workpieces  1  and  2 , the complete locking arm  4  is supported as a normal beam since the outer face  11   a  is in contact with the inner slope  21  of the second guide  7  as both workpieces  1  and  2  are pushed into each other. Therefore, great force is required to warp the complete locking arm  4 . This prevents the complete locking from being released inadvertently. 
     The complete locking can be released by pulling both workpieces by the force greater than that required for releasing the provisional locking so that the workpieces  1  and  2  are shifted into the provisional locking state shown in FIG.  2 . 
     In accordance with this embodiment, the complete locking force can be improved and the intermediate warping hole in the conventional locking arm is not required. This permits the locking arms  3 ,  4  and arm receiving portion  5  to be molded forcibly from a mold in resin molding. The molding die is simplified and the production cost can be reduced. 
     Referring to FIGS. 5 to  7 , an explanation will be given of an application of the locking structure shown in FIGS. 1 to  4 . 
     FIG. 5 shows an embodiment of a holder-equipped connector. A holder-equipped connector  26  includes a male connector housing  27  of synthetic resin which serves as the one workpiece, a front holder  28  of synthetic resin which serves as the other workpiece combined with the connector housing  27  from the front to form a terminal chamber  30 , and a wire-equipped female terminal  29  which is inserted from the rear into the connector housing  27 . 
     The connector housing  27  includes a hood  31  and a housing body  33  arranged within an internal space  32  of the hood  31 . The housing body  33  is composed of a horizontal upper wall  34 , a short lower wall  35 , a vertical partition  36  and a resilient terminal locking lance  37 . A waterproof packing  38  for a complementary female connector (not shown) is mounted on the base of the housing body  33 . 
     A front holder  28  is formed in a square-ring shape so as to have upper and lower slit-like vacant chambers  39 ,  40  and a plate wall  41  arranged therebetween to stop the warping of the lance. The upper wall  34  of the housing body  33  is adapted to advance into the upper vacant chamber  39  and the partition  36  is adapted to advance into the lower vacant chamber  40 . 
     The pair of left and right horizontal locking arms  3  and  4  (FIG. 1) are attached on the upper wall  34  of the housing body  33 . The arm receiving portion  5  (FIG. 1) and the pair of arm guides  6  and  7  (FIG. 1) which correspond to the locking arms  3  and  4  are provided in the upper vacant chamber  39  of the front holder  28 . In the state as shown in FIG. 5, the front holder  28  is provisionally locked by these locking means  3  to  5 . 
     FIG. 6 is a front view of the connector housing  27 . The housing connector  27  includes the housing body  33  within the internal space  32  of the hood  31 . The pair of left and right locking arms  3  and  4  are integrally attached to the upper wall  34  of the housing body  33 . The locking arms  3  and  4  are formed flush with the upper wall  34  to cut out the center of the upper wall  34 . The locking arms  3  and  4  can warp horizontally. A space  43  is formed beneath the locking arms  3  and  4  so that it can accommodate the plate wall  41  for stopping the warp of the locking lance of the front holder (FIG.  5 ). Below the space  43 , a terminal accommodating space which constitutes terminal chambers is formed. 
     FIG. 7 is a perspective view of the front holder  28  of which the main part is recessed. The above arm receiving portion  5  is integrally formed between an upper wall  44  and the plate wall  41  for stopping the warp of the lance. The arm receiving portion  5  is composed of a square bar-like receiving body  14  which extends straight in a terminal inserting direction or holder inserting direction and the provisional engaging projection  15  and complete engaging projection  16  which are separately formed on both sides of the tip. 
     The first arm guide  6  is formed on the one side of the arm receiving portion  5 . The first arm guide  6  has a straight face  20  in parallel to the receiving body  14  and a short slope  19 . The second arm guide  7  is formed on the other side of the arm receiving portion  5 . The second arm guide  7  has a long slope  21  and a short straight face  22 . The arm receiving portion  5  and the arm guide portions  6 ,  7  are formed as walls which couple the upper wall  44  and plate wall  41  with each other. 
     By weakly pushing the front holder  28  into the connector housing  27 , as shown in FIG. 5, the front holder  28  is surely provisionally locked into the connector housing  27  with the aid of the provisional engaging protection  15  of the arm receiving portion  15  and the provisional locking projection  8  of the provisional locking arm  3 . In this state, the terminal  29  is inserted and secured in the connector housing  27 . Subsequently, by strongly pushing the front holder  28  into the connector housing in a direction opposite to that of inserting the terminal  29 , the front holder  28  is surely completely locked into the connector housing  27  by strong locking force with the aid of the complete engaging projection  16  of the arm receiving portion  5  and the complete locking projection  12  of the complete locking arm  4 . 
     FIGS. 5 to  7  show an application of the locking structure to a male connector  26 . On the other hand, where the locking structure is to be applied to a female connector (not shown), for example, the pair of arms  3  and  4  are horizontally formed to project without employing the upper wall  34  of the housing body  33 . The arm receiving portion  5  of the front holder  28  is formed integrally to the plate wall  41  in a space with the upper wall recessed. The structure of each of these locking arms  3 ,  4 , arm receiving portion  5  and arm guides  6 ,  7  is exemplary, and can be modified according to the form of the workpiece such as the connector housing  27  and front holder  28 . 
     Further, in FIG. 1, the pair of locking arms  3 ,  4  may be attached to the front holder  2  whereas the arm receiving portion  5  and arm guides  6 ,  7  may be attached to the connector housing  1 . The locking structure shown in FIG. 1 can be applied to an electric connection box, rear holder, etc. (not shown) other than the connector housing  1  and front holder  2 . 
     Incidentally, the contents to Japanese Patent Appln. No. 2001-232009 filed on Jul. 31, 2001 are hereby incorporated by reference.