Abstract:
A joining structure of a connector is provided with one connector having a plurality of engaging portions and another connector having the same number of engaging portions as the number of a plurality of engaging portions in one connector, and a plurality of engaging portions in one connector and a plurality of engaging portions in another connector are mutually corresponded so as to form a plurality of engaging pairs. In this structure, a plurality of engaging portions in one connector and a plurality of engaging portions in another connector respectively have shapes so that the respective engaging portions can correspondingly engage with each other so as to form a plurality of engaging pairs in the case that one connector and another connector are joined in a proper direction, and at least one of pairs between a plurality of engaging portions in one connector and a plurality of engaging portions in another connector can not engage with each other in the case that one connector and another connector are joined in an improper direction.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a joining structure of a connector, and more particularly to a joining structure between connectors in each of which a terminal portion of a wire harness is connected and arranged within a connector housing. 
     Conventionally, in order to improve a handling property of a plurality of connectors, there is proposed a joining structure of a connector for joining connectors to each other. 
     Such joining structure of the connector includes a structure using an engaging projection and an engaging groove. 
     SUMMARY OF THE INVENTION 
     In accordance with a consideration of the inventors of the present application, the joining structure of the connector includes a structure in which connectors  1  and  4  are joined and combined with each other by sliding a side surface  3  of a connector housing  2  in one connector  1  along a side surface  6  of a connector housing  5  in another connector  4 , as shown in FIG.  8 . 
     Illustration is omitted, however, a connection metal fitting is installed and arranged in the connector housing  2  and the connector housing  5 . A terminal of a wire harness W is connected to the connection metal fitting, as shown in FIGS. 9 and 10. 
     The respective connectors  1  and  4  are structured such as to be connected to separately prepared connectors (not shown) so as to be electrically connected. 
     These connectors  1  and  4  are joined in accordance with an operation that two engaging portions  7  and  8  having the same shape and the same size and formed on the side surface  3  of one connector  1  along a height direction are engaged with two engaged groove portions  9  and  10  having the same shape and the same size and formed on the side surface  6  of another connector  4  along a height direction. 
     The connector  1  and the connector  4  are joined to each other in the manner as mentioned above, thereby intending to improve an arrangement and a mounting operation of the wire harness W. 
     The engaging portion  7  formed on the side surface  3  in one connector  1  side is constituted by a pair of engaging pieces  7 A and  7 B and the engaging portion  8  is constituted by a pair of engaging pieces  8 A and  8 B, as shown in FIG.  8 . Further, the engaging pieces  7 A and  7 B constituting the engaging portion  7  are formed so as to protrude in an oblique direction mutually moving apart from the side surface  3 . The engaging pieces  8 A and  8 B constituting the engaging portion  8  are protruded in an oblique direction mutually moving apart in the same manner. 
     The engaged groove portions  9  and  10  formed on the side surface  6  in another connector  4  side are structured such that the engaging portions  7  and  8  mentioned above are slid therealong and fitted thereto. 
     That is, both side walls of the engaged groove portions  9  are formed in an inverted taper shape, and are structured such as to be brought into contact with inner side surfaces (surfaces opposing to the side surface  3 ) of the engaging pieces  7 A and  7 B in a state of inserting the engaging portion  7 . Further, both side walls of the engaged groove portion  10  are also formed in an inverted taper shape in the same manner, and are structured such as to be brought into contact with inner side surfaces (surfaces opposing to the side surface  3 ) of the engaging pieces  8 A and  8 B in a state of inserting the engaging portion  8 . 
     Since two sets of engaging portions and engaged groove portions are formed in the manner mentioned above, in comparison with the case that one set of engaging portion and engaged groove portion are formed, it is possible to prevent the connectors  1  and  4  from being shaky and rickety between the both. 
     FIG. 9 is a schematic view showing a direction between the connectors  1  and  4  in which the connector  1  and the connector  4  can be suitably jointed. As shown in FIG. 9, in a normally joined state, the connectors land  4  are combined with each other so that the engaging portion  7  of the connector  1  corresponds to the engaged groove portion  9  of the connector  4  and the engaging portion  8  of the connector  1  corresponds to the engaged groove portion  10  of the connector  4 . 
     However, in the joining structure of the connector mentioned above, since two joining portions  7  and  8  of the connector  1  have the same shape and the same size and the engaged groove portions  9  and  10  of the connector  2  have the same shape and the same size, the engaging portion  8  can engage with the engaged portion  9  and the engaging portion  7  can engage with the engaged portion  10 , respectively in the case that the connectors  1  and  4  are inversely joined in a longitudinal direction, as shown in FIG.  10 . Accordingly, it is preferable to suppose that an operator erroneously handle the direction of the connector. 
     Further, since in many cases, the operation of joining the connectors  1  and  4  mentioned above is performed in a narrow place where a state of the connectors  1  and  4  is hard to be recognized and it is hard to find an error in the joining direction, it is preferable to further employ any countermeasure. 
     Since it is hard to find the error in the joining direction when joining the connectors in which the wire harnesses W having different wiring directions are mounted to each other, the error is first found at a time of joining the combined connector to the separately prepared connector to be joined, so that a case giving a trouble to the operation can be supposed. 
     In the case of engaging the connectors with each other in the erroneous joining direction as mentioned above, it is necessary to take out both of the connectors and again rejoin them. 
     Accordingly, there is a problem that a smooth joining operation is hard to be performed in the case of the joining structure of the connector considered above. 
     Accordingly, an object of the present invention is to provide a joining structure of a connector in which connectors can be suitably and smoothly joined and an operability is improved. 
     In accordance with the present invention, there is provided a joining structure of a connector comprising: one connector having a plurality of engaging portions; and another connector having the same number of engaging portions as the number of a plurality of engaging portions in one connector, a plurality of engaging portions in one connector and a plurality of engaging portions in another connector being mutually corresponded so as to form a plurality of engaging pairs. In this structure, a plurality of engaging portions in one connector and a plurality of engaging portions in another connector respectively have shapes so that the respective engaging portions can correspondingly engage with each other so as to form a plurality of engaging pairs in the case that one connector and another connector are joined in a proper direction, and at least one of pairs between a plurality of engaging portions in one connector and a plurality of engaging portions in another connector can not engage with each other in the case that one connector and another connector are joined in an improper direction. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view explaining a joining state in a joining structure of a connector in accordance with a first embodiment of the present invention; 
     FIG. 2 is a plan view showing a proper joining arrangement of the connectors in accordance with the embodiment; 
     FIG. 3 is a plan view showing an improper joining arrangement of the connectors in accordance with the embodiment; 
     FIG. 4 is a plan view of a main portion in a joining step of the connector in accordance with the embodiment; 
     FIG. 5 is a plan view of a main portion in a joining step of the connector; 
     FIG. 6 is a plan view of a joining structure of a connector in accordance with a second embodiment of the present invention; 
     FIG. 7 is a plan view of a joining structure of a connector in accordance with a third embodiment of the present invention; 
     FIG. 8 is a perspective view showing a joining structure of a connector in accordance with a consideration of the inventors of the present invention; 
     FIG. 9 is a plan view showing a proper joining arrangement of the connectors; and 
     FIG. 10 is a plan view showing an improper joining arrangement of the connectors. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A description will be in detail given below of each of embodiments of a joining structure of a connector in accordance with the present invention with reference to the accompanying drawings. 
     At first, a description will be in detail given below of a first embodiment of a joining structure of a connector in accordance with the present invention with reference to FIGS. 1 to  5 . 
     As shown in FIG. 1 showing a state before two connectors  11  and  12  having the same shape are combined, the connector  11  has a substantially rectangular parallelepiped-shaped connector housing  11 A made of a synthetic resin having an electrically insulating property. 
     A plurality of terminal receiving chambers  14  are formed within the connector housing  11 A in such a manner as to extend through from a front surface side to a rear surface side. Terminal metal fittings (not shown) for respectively joining ends of wire harnesses W (shown in FIGS. 2 and 3) are arranged and fixed within the terminal receiving chamber  14 . 
     Engaging portions  16  and  17  corresponding to a joining projection are respectively formed on one side surface  15  of the connector housing  11 A at a predetermined interval along a height direction of the connector housing  11 A. The engaging portion  16  is formed so as to be positioned in a rear portion side on the side surface  15  of the connector housing  11 A. Further, the engaging portion  17  is formed so as to be positioned in a front portion side on the side surface  15  of the connector housing  11 A. 
     Here, a description will be given of a structure of the engaging portion  16 . 
     The engaging portion  16  is constituted by two plate-like engaging pieces  16 A and  16 B formed so as to obliquely protrude in a different direction from each other (a forward direction and a backward direction) with respect to the side surface  15  in such a manner as to form a predetermined angle (for example, about 20 to 45 degrees), and an erroneous join prevention protruding portion  16 C formed so as to protrude between the engaging pieces  16 A and  16 B. 
     The engaging pieces  16 A and  16 B and the erroneous join prevention protruding portion  16 C are integrally formed in the connector housing  11 A, and are made of the same synthetic resin as that of the connector housing  11 A. The engaging pieces  16 A and  16 B are extended along a height direction of the connector housing  11 A. Further, the erroneous join prevention protruding portion  16 C is structured such as to protrude from a bottom portion of a groove formed between the engaging pieces  16 A and  16 B toward a side portion of the side surface  15  and is extended along the height direction of the connector housing  11 A. Further, guiding taper surfaces  16   a  and  16   b  are formed in upper portions of the engaging pieces  16 A and  16 B. 
     Next, a description will be given of a structure of the engaging portion  17 . 
     The engaging portion  17  is constituted by two plate-like engaging pieces  17 A and  17 B formed so as to obliquely protrude in a different direction from each other (a forward direction and a backward direction) with respect to the side surface  15  of the connector housing  11 A in such a manner as to form a predetermined angle (for example, about 20 to 45 degrees). 
     The engaging pieces  17 A and  17 B are integrally formed in the connector housing  11 A, and are made of the same synthetic resin as that of the connector housing  11 A. The engaging pieces  17 A and  17 B are extended along a height direction of the connector housing  11 A so as to have the same height as that of the engaging pieces  16 A and  16 B of the engaging portion  16 . Further, guiding taper surfaces  17   a  and  17   b  are formed in upper portions of the engaging pieces  17 A and  17 B. 
     A step portion  15 A having the same protruding size as a protruding size between the side surface  15  and front end surfaces of the engaging pieces  16 A,  16 B,  17 A and  17 B is formed in a lower portion of the side surface  15  on which the engaging portions  16  and  17  are formed. The step portion  15 A has a positioning function for defining a mutual height position in a state of being joined to the connector  12  to be joined. Further, an engaging recess portion  15 B is formed in each of upper portions of both sides of the side surface  15 . 
     Next, a description will be given of a structure of the connector  12  joined to the connector  11 . 
     As shown in FIG. 1, the connector  12  has the same shape as that of the connector  11  mentioned above. That is, in accordance with the present embodiment, two series of combination connectors and three series of combination connectors can be assembled by preparing plural sets of one kind of connectors. 
     The connector  12  has a connector housing  12 A in which a plurality of terminal receiving portions  21  are formed, and engaging portions  19  and  20  having the same structure as those of the engaging portions  16  and  17  in the connector  11  mentioned above and an engaging recess portion  18 B are formed on one side surface  18  of the connector housing  12 A. 
     On the contrary, engaged groove portions  23  and  24  corresponding to a joining groove portion are formed on another side surface  22  of the connector housing  12 A at a predetermined interval along a height direction of the connector housing  12 A. 
     A position at which the engaged groove portion  23  is formed corresponds to a position opposite to the engaging portion  19  formed on the side surface  18  in the connector housing  12 A. The engaged groove portion  23  corresponds to the engaging portion  16  of the connector  11  in the case of joining the connector  11  to the connector  12 , and the structure is made such that the engaging portion  16  is inserted to the engaged groove portion  23  from a lower side, as shown by a single dot chain line in FIG.  1 . 
     The engaged groove portion  23  is structured such that an inverted taper surface  23 A engaging with a back surface (a surface opposing to the side surface  15 ) of the engaging piece  16 A and an inverted taper surface  23 B engaging with a back surface of the engaging piece  16 B are formed so that the inserted engaging portion  16  is not taken out to a side portion. Further, a depth of the engaged groove portion  23  is set to substantially equal to a height between the side surface  15  in the connector  11  and the front end surfaces of the engaging pieces  16 A and  16 B (a size between the side surface  18  and the front end surfaces of the engaging pieces  19 A and  19 B). 
     A position at which the engaged groove portion  24  is formed corresponds to a position opposite to the engaging portion  20  formed on the side surface  18  in the connector housing  12 A. Further, the engaged groove portion  24  corresponds to the engaging portion  17  of the connector  11  in the case of joining the connector  11  to the connector  12 , and the structure is made such that the engaging portion  17  is inserted to the engaged groove portion  24  from a lower side, as shown by a single dot chain line in FIG.  1 . 
     In the engaged groove portion  24 , an inverted taper surface  24 A engaging with a back surface of the engaging piece  17 A and an inverted taper surface  24 B engaging with a back surface of the engaging piece  17 B are formed so that the inserted engaging portion  17  is not taken out to a side portion. Further, a depth of the engaged groove portion  24  is set to substantially equal to a height between the side surface  15  in the connector  11  and the front end surfaces of the engaging pieces  17 A and  17 B (a size between the side surface  18  and the front end surfaces of the engaging pieces  20 A and  20 B). Further, an erroneous join prevention protruding portion  24 C is formed in a bottom portion of the engaged groove portion  24  along a height direction (a groove direction) of the connector housing  12 A. 
     A step portion  22 A recessed toward the side surface  18  side from the side surface  22  is formed in a lower portion of the side surface  22  on which the engaged groove portions  23  and  24  are formed. Further, engaging convex portions  22 B and  22 B engaged with the engaging recess portions  15 B and  15 B mentioned above are respectively formed in both sides of the upper portion of the side surface  22 . 
     Here, a description will be given of a side surface  29  of the connector  11 . 
     As mentioned above, since the connector  11  and the connector  12  have the same structure, the side surface  29  has the same structure as that of the side surface  22  of the connector  12 . That is, as shown in FIG. 1, an engaged groove portion  25  having the same shape as that of the engaged groove portion  23  of the connector  12  and an engaged groove portion  26  having the same shape as that of the engaged groove portion  24  of the connector  12  are formed on the side surface  29 . 
     Next, a description will be given of a method of joining the connector  11  to the connector  12 , an operation and an effect thereof. 
     At first, as shown in FIGS. 1 and 2, the engaging portion  17  of the connector  11  is inserted to the engaged groove portion  24  of the connector  12  at the same time when the engaging portion  16  of the connector  11  is inserted to the engaged groove portion  23  of the connector  12 . 
     At this time, the connector  12  is operated so as to slide the side surface  15  and the side surface  22  toward the upper portion of the connector  11  from the lower portion thereof. 
     Then, since the guiding taper surfaces  16   a ,  16   b ,  17   a  and  17   b  are formed in the upper portions of the engaging pieces  16 A,  16 B,  17 A and  17 B constituting the engaging portions  16  and  17 , at an initial time of inserting, these guiding taper surfaces  16   a ,  16   b ,  17   a  and  17   b  are engaged with the lower edges of the inverted taper surfaces  23 A,  23 B,  24 A and  24 B of the engaged groove portions  23  and  24  in the connector  12  side. 
     As a result, the engaging pieces  16 A,  16 B,  17 A and  17 B are received within the corresponding engaged groove portion. 
     Next, when a slide operation is performed so as to lift up the connector  11  with respect to the connector  12 , the engaging convex portions  22 B and  22 B protruded from both sides of the upper portion of the side surface  22  in the connector  12  is engaged with the upper edge of the side surface  15  of the connector  11  and subsequently engaged with the side surface  15 . 
     At this time, since the engaging convex portions  22 B and  22 B have a predetermined height, the engaging convex portions  22 B and  22 B have an operation of moving apart the side surface  15  and the side surface  22  at a predetermined distance d as shown in FIG.  4 . 
     In accordance with this, the engaging pieces  16 A,  16 B,  17 A and  17 B engaging with the inverted taper surfaces  23 A,  23 B,  24 A and  24 B of the engaged groove portions  23  and  24  are pressed in a direction shown by an arrow in FIG.  4  and elastically deformed. 
     Next, when further increasing the connector  11  with respect to the connector  12 , the engaging recess portions  15 B and  15 B are aligned with the engaging convex portions  22 B and  22 B, and the engaging convex portions  22 B and  22 B are received in the engaging recess portions  15 B and  15 B as shown in FIG.  5 . At the same time, the step portion  15 A in the connector  11  side and the step portion  22 A in the connector  12  side are brought into contact with each other, and a positioning is performed so that the connector  11  does not move upward any more with respect to the connector  12 . 
     At this time, the inverted taper surface  22 A and  22 B are pressed back due to a reaction force of the engaging pieces  16 A,  16 B,  17 A and  17 B, whereby a distance between the side surface  15  and the side surface  22  is reduced so as to be stabilized in a state shown in FIG.  5 . FIGS. 4 and 5 show a relation between the engaging portion  16  and the engaged groove portion  23 , however, the same relation can be applied to a relation between the engaging portion  17  and the engaged groove portion  24 . 
     In an arrangement state of the connector  11  and the connector  12  mentioned above, as shown in FIG. 2, since the engaging portion  16  having the erroneous join prevention protruding portion  16 C and the engaged groove portion  23  having no erroneous join prevention protruding portion are combined with each other, and the engaged groove portion  24  having the erroneous join prevention protruding portion  24 C and the engaging portion  17  having no erroneous join prevention protruding portion are combined with each other, it is possible to join the connector  11  to the connector  12 . 
     On the contrary, as shown in FIG. 3, in the case that the direction of the connector  12  is inverted to the connector  11 , when it is intended to combine both connectors, the engaging portion  16  corresponds to the engaged groove portion  24 , and the erroneous join prevention protruding portion  16 C of the engaging portion  16  and the erroneous join prevention protruding portion  24 C are interfered with each other, so that a join between the connector  11  and the connector  12  is not established. 
     As mentioned above, in accordance with the present embodiment, the structure is made such that the erroneous join prevention protruding portion  16 C is formed in the engaging portion  16  of the connector  11 , the erroneous join prevention protruding portion  16 C can be received in the engaged groove portion  23  corresponding to the engaging portion  16  at a time of joining and inserting, the erroneous join prevention protruding portion is not formed in the engaging portion  17  of the connector  11 , the erroneous join prevention protruding portion  24 C is formed in the engaged groove portion  24  corresponding thereto, and the erroneous join prevention protruding portion  24 C is received in the groove between the engaging pieces  17 A and  17 B of the engaging portion  17 . 
     It is possible to realize a joining structure of a connector which can securely and effectively prevent a play or the like from being generated, can effectively prevent an erroneous join in the case that the connectors have different longitudinal directions in a joining state, and can smoothly and securely perform a joining operation of the connector, on the basis of a simple structure. 
     In this case, in the present embodiment, the connector  11  and the connector  12  are set to have the same shape, however, the structure is not limited to this, it is possible to join connectors having different shapes and structures as far as the engaging portion and the engaged groove portion have the corresponding positional relation. 
     For example, the structure may be made such as to join the connectors having different number of connectable wire harnesses W in the connectors to be mutually joined. 
     Further, in accordance with the present embodiment, the two series of combined connector is obtained by the joining structure, however, the structure can be made such that a multiple series of combined connector more than two is obtained. 
     Next, a description will be in detail given of a second embodiment of a joining structure of a connector in accordance with the present invention with reference to FIG.  6 . 
     As shown in FIG. 6, in accordance with the present embodiment, the structure is made such that one connector  31  is joined to another connector  32 , and is basically the same as the structure of the first embodiment. Engaged groove portions  34  and  35  are formed on one side surface  33  of the connector  31  and engaging portions  37  and  38  are formed on another side surface  36 . 
     The engaged groove portions  34  and  35  are structured such that a width of a groove opening portion is formed narrower than a width of a groove bottom portion in the same manner as the shape of the engaged groove portion in accordance with the first embodiment mentioned above. Further, an erroneous join prevention protruding portion  35 A is formed in a bottom portion of one engaged groove portion  35  among the engaged groove portions  34  and  35  along a vertical direction of the connector. 
     The engaged groove portions  37  and  38  are structured such that a width of a base portion in a side surface  36  side is set to be narrow and a width in a front end side is set to be wide and a cross sectional shape is formed in a substantially equilateral triangle shape. The engaging portion  37  is formed at a corresponding position in an opposite side of the engaged groove portion  34  mentioned above in the connector  31 , and the engaging portion  38  is formed at a corresponding position opposite to the engaged groove portion  35 . Further, a protrusion receiving groove portion  38 A is formed at a center in a width direction of the front end surface of the engaging portion  38  along a vertical direction. 
     The connector  32  has substantially the same structure as that of the connector  31 , and engaged portions  39  and  40  corresponding to the engaged grove portions  34  and  35 , and engaging portions  41  and  42  corresponding to the engaging portions  37  and  38  are formed therein. In this case, the other structures in the present embodiment are the same as those of the first embodiment mentioned above. 
     In the present embodiment mentioned above, it is possible to intend to join both of the connectors  31  and  32  by inserting the joining portions  37  and  38  of the connector  31  to the engaged groove portions  39  and  40  of the connector  32 . 
     Then, since an erroneous join prevention protruding portion  40 A is protruded in a bottom portion of the engaged groove portion  40 , it is possible to effectively prevent an erroneous join by preventing the engaging portion  37  of the connector  31  from being inserted. 
     In this case, also in accordance with the present embodiment, the connector  31  and the connector  32  are set to have the same shape, however, the structure is not limited to this, it is possible to join connectors having different shapes and structures with each other as far as the engaging portion and the engaged groove portion have the corresponding positional relation. 
     Further, also in accordance with the present embodiment, the two series of combined connector is obtained by the joining structure, however, a multiple series of combined connector more than two can be obtained. 
     Next, a description will be in detail given of a third embodiment of a joining structure of a connector in accordance with the present invention with reference to FIG.  7 . 
     As shown in FIG. 7, in accordance with the present embodiment, the structure is made such that a connector  51  is joined to a connector  52 , and is basically the same as the structure of the first embodiment. An engaged groove portion  54  having a long width and an engaged groove portion  55  having a short width are formed on one side surface  53  of the connector  51  and an engaging portion  57  having a long width and an engaging portion  58  having a short width are formed on another side surface  56 . 
     Another connector  52  has substantially the same structure as that of the connector  51 , in which engaged groove portions  60  and  61  having the same structure as the engaged groove portions  54  and  55  mentioned above are formed on one side surface  59 , and engaging portions  63  and  64  having the same structure as the engaging portions  57  and  58  mentioned above are formed on another side surface  62 . 
     In the third embodiment having the structure mentioned above, it is set such that the engaging portion  57  having a long width can be inserted to the engaged groove portion  60  having a long width, the engaging portion  58  having a short width can be inserted to the engaged groove portion  61  having a short width, and the engaging portion  57  having a long width can not be inserted to the engaged groove  61  having a short width. In this case, the other structures of the present embodiment are the same as those of the first embodiment mentioned above. 
     In accordance with the present embodiment mentioned above, it is possible to intend to join both of the connectors  51  and  52  by inserting the engaging portions  57  and  58  of the connector  51  in correspondence to the engaged groove portions  60  and  61  of the connector  52 , and the join between the connector  51  and the connector  52  can be allowed only in the corresponding relation between the engaging portions  57  and  58  and the engaged groove portions  60  and  61 , so that it is possible to effectively prevent an erroneous join by preventing the engaging portion  58  of the connector  51  from being inserted to the engaged groove portion  61  of the connector  52 . 
     Further, also in accordance with the present embodiment, the connector  51  and the connector  52  are set to have the same shape, however, the structure is not limited to this, it is possible to join connectors having different shapes and structures to each other by corresponding the engaging portion to the engaged groove portion in the positional relation. 
     Further, also in the present embodiment, the two series of combined connector is obtained by the joining structure, however, a multiple series of combined connector more than two can be obtained. 
     As mentioned above, each of the embodiments is described, however, the present invention can be variously modified in accordance with the aspects of the structure. 
     For example, in each of the embodiments mentioned above, there is employed the structure in which two sets of engaging portions and engaged groove portions are formed on the side surface of the respective connectors, however, the structure may be made such that three of more sets of engaging portions and engaged groove portions are respectively formed on one side surface. 
     Further, in the first and second embodiments mentioned above, the erroneous join prevention protruding portions  16 C,  24 C and  40 A are formed along the height direction of the connector so as to have a length substantially equal to the height, however, since it is sufficient to substantially prevent the erroneous join, for example, a projection-like portion is formed by separating the side surface of the connector into upper and lower portions. 
     In addition, it is of course that the present invention can be realized by variously modifying the structure within a range of the technical feature of the present invention.