Abstract:
An electrical junction box having a in which a plurality of connecting bolts are juxtaposed on a bolt support section and that exerts excellent strength to realize a reinforcing structure without interfering with mounting of a connecting plate onto the connecting bolts. Inserting slits are provided in a peripheral wall and a proximal end of a partition wall. A connecting plate is previously disposed through the slits on one surface of a bolt support section. A plurality of connecting bolts are attached to the bolt support section so that the bolt support section bridges the plural connecting bolts.

Description:
BACKGROUND 
       [0001]    This application claims priority to Japanese Patent Application No. JP2009-248269, filed in Japan on Oct. 28, 2009, the entire disclosure of which is hereby incorporated by reference. 
         [0002]    The exemplary embodiments of the present invention relate to an electrical junction box to be mounted on a motor vehicle, and more particularly relates to an electrical junction box provided with connecting bolts to which external terminals are coupled. 
         [0003]    Heretofore, a structure equipped with connecting bolts has been known in an electrical junction box. Connecting terminals (external terminals) of external circuits are coupled to the connecting bolts in order to connect the external circuits to internal circuits. For example, JP HET 11(1999)-7990 A has disclosed an electrical junction box in which connecting bolts are electrically coupled to internal circuits, external terminals are attached to the connecting bolts and the terminals and bolts are fastened to one another by nuts to connect the external circuits to the internal circuits. 
         [0004]    Since the respective connecting bolts are subject to fastening forces upon securing of the external terminals, a bolt support section in the electrical junction box requires great strength. As disclosed in Patent Document 1, the bolt support section is provided with a peripheral wall that surrounds the connecting bolts, thereby preventing a short circuit and enhancing strength. 
         [0005]    However, in the case where a plurality of connecting bolts are juxtaposed on the bolt support section, there is a problem that the peripheral wall cannot exert a sufficient reinforcement effect. That is, in many cases, a plurality of connecting bolts are provided in the electrical junction box in order to connect the internal circuits to the external circuits, and the connecting bolts and connecting plates are electrically interconnected to each other to define branched circuits. In this case, a sufficient reinforcement effect cannot be obtained by the peripheral wall that surrounds a whole outer periphery of the bolt support section on which a plurality of connecting bolts are provided. 
         [0006]    It may be intended that a partition wall for partitioning adjacent connecting bolts is integrally provided on the bolt support section in addition to the peripheral wall that surrounds the whole outer periphery of the bolt support section. However, such partition wall will make it difficult to bridge the adjacent connecting bolts by the connecting plate. 
       SUMMARY 
       [0007]    In view of the above problems, an object of the present invention is to provide an electrical junction box having a new structure in which a plurality of connecting bolts are juxtaposed on a bolt support section and that exerts excellent strength to realize a reinforcing structure without interfering with mounting of a connecting plate onto the connecting bolts. 
         [0008]    A first exemplary embodiment is directed to an electrical junction box. In the electrical junction box in the first aspect, a plurality of connecting bolts are attached to a bolt support section, and the connecting bolts are fastened to and secured to external terminals by nuts. A plurality of bolt receiving apertures are provided side by side in the bolt support section. The bolt support section is provided integrally on the one surface with a peripheral wall that surrounds the bolt receiving apertures and with a partition wall provided inside the peripheral wall for partitioning the adjacent bolt receiving apertures. Inserting slits are provided in the peripheral wall and a proximal end of the partition wall. A connecting plate is provided with bolt inserting apertures at positions corresponding to the bolt receiving apertures. The connecting plate is inserted into the inserting slits so that the connecting plate is disposed on the one surface of the bolt support section. The connecting bolts pass through the bolt receiving apertures and bolt inserting apertures from the other surface of the bolt support section to be attached to the bolt support section. 
         [0009]    According to the electrical junction box in the first exemplary embodiment, it is possible to reinforce the periphery around the bolt receiving apertures in the bolt support section by the peripheral wall that surrounds the whole outer peripheral wall of the bolt support section and the partition wall that partitions the adjacent connecting bolts. In addition, it is possible to dispose the connecting plate on the one surface of the bolt support section while maintaining the peripheral wall and partition wall by providing the slits in the peripheral wall and the proximal end of the partition wall. Thus, since the connecting plate is directly contacted with the external terminals and the plate and terminals are fastened to each other by the nuts, it is possible to enhance an electrical current conductive efficiency while obtaining sufficient strength for the bolt support section. 
         [0010]    Since the connecting plate is inserted into the inserting slits in the peripheral wall and proximal end of the partition wall to be attached to the electrical junction box, it is possible to prevent the connecting plate from being disengaged from the bolt support section after the connecting plate is disposed on the bolt support section. Accordingly, it is possible to maintain a stable arrangement of the connecting plate on the bolt support section even upon transportation of the electrical junction box. 
         [0011]    According to a second exemplary embodiment, the connecting bolts are inserted into the bolt inserting apertures from the other surface of the bolt support section. The connecting bolts are restrained from turning about central axes and are prevented from being disengaged from the bolt inserting apertures. Bolt holding means maintains an attaching condition of the connecting bolts to the bolt support section. 
         [0012]    According to the electrical junction box of the second exemplary embodiment, it is possible to maintain a stable attaching condition of the connecting bolts on the bolt support section. Consequently, it is possible to stabilize a mounting condition of the connecting plate to the plural connecting bolts. 
         [0013]    In a third exemplary embodiment, a bus bar that constitutes internal circuits is incorporated in the box. The bus bar is integrally provided with bus bar terminal portions having bolt inserting apertures. The bus bar terminal portions are inserted into the bolt receiving apertures from the other surface of the bolt support section to be superimposed on the connecting plate. The connecting bolts are inserted into and fastened to the bolt inserting apertures. 
         [0014]    According to the electrical junction box in the third exemplary embodiment, it is possible to fasten the external terminals, connecting plate, and bus bar terminal portions under the condition where they are superimposed on one another directly. In result, it is possible to enhance an electrical current conductive efficiency from the external terminals to the bus bar. 
         [0015]    In a fourth exemplary embodiment, the slits are provided in the peripheral wall at the one side and a proximal end of the partition wall in an inserting direction of the connecting plate. A latch recess is provided in the peripheral wall at the other side. The connecting plate is provided on an inserting end with a latch projection. The latch projection is engaged with the latch recess to constitute means for restraining displacement of the connecting plate. 
         [0016]    According to the electrical junction box of the fourth exemplary embodiment, it is possible to prevent the connecting plate from moving in a direction perpendicular to the inserting direction of the connecting bolts, before the connecting bolts are attached to the bolt support section. Thus, it is possible to enhance accuracy in positioning between the bolt inserting apertures and the bolt receiving apertures. Consequently, it is easy to insert the connecting bolts insert into the bolt inserting apertures and bolt receiving apertures. 
         [0017]    According to embodiments of the present invention, the connecting plate is previously inserted into the slits in the peripheral wall and proximal end of the partition wall and is previously disposed on the one surface of the bolt support section, a plurality of connecting bolts are attached to the bolt support section, and the connecting plate are mounted on the plural connecting bolts. Thus, although the partition wall is provided on the bolt support section to reinforce it, it is possible to avoid interference between the plural connecting bolts and the connecting plate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a plan view of a fuse box in an embodiment of an electrical junction box in accordance with the present invention; 
           [0019]      FIG. 2  is a cross section view taken along lines II-II in  FIG. 1 ; 
           [0020]      FIG. 3  is a partially broken longitudinal section view taken along lines III-III in  FIG. 1 ; 
           [0021]      FIG. 4  is a plan view of a casing main body that constitutes the fuse box shown in  FIG. 1 , illustrating the casing main body on which a bus bar is mounted; 
           [0022]      FIG. 5  is a bottom side view of the casing main body shown in  FIG. 4 ; and 
           [0023]      FIGS. 6A to 6C  are explanatory views that illustrate assembling steps of the fuse box shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0024]    Referring now to the drawings, embodiments of the present invention will be described below. 
         [0025]      FIGS. 1 to 3  show a fuse box  10  as an embodiment of an electrical junction box. The fuse box  10  includes a casing main body  12 , an upper cover (not shown) attached to the fuse box  10  from an upper side, a lower cover (not shown) attached to the fuse box  10  from a lower side. The fuse box  10  is installed in a rear part of a vehicle body of a motor vehicle. Hereinafter, a vertical direction designates upper and lower directions in  FIGS. 2 and 3  in principle. 
         [0026]    Specifically, as shown also in  FIGS. 4 and 5 , the casing main body  12  is formed into a rectangular block-like configuration, as a whole. A size in a longitudinal direction (right and left directions in  FIG. 4 ) is set to be sufficiently larger than a size in a lateral direction (upper and lower directions in  FIG. 4 ). The casing main body  12  is provided with a bolt support section  14 . Two connecting bolts  16   a  and  16   b  are attached to the bolt support section  14 . An external terminal  20   a  of an electrical cable  18   a  from a battery disposed in a rear part of the vehicle body, while external terminal  20   b  of an electrical cable  18   b  to be connected to an electrical junction box disposed in a front part of the vehicle body. The casing main body  12  is further provided with relay mounting sections  22  and  24 , and fuse mounting sections  26  that are open upward. Relays and fuses (not shown) are mounted on the relay mounting sections  22  and  24 , and the fuse mounting sections  26 . 
         [0027]    The bolt support section  14  is formed into a substantially rectangular plate-like configuration. An upper surface  28  that is the one surface in a thickness direction and a lower surface  30  that is the other surface in the thickness direction spread in a direction perpendicular to a height direction of the casing main body  12 . Two bolt receiving apertures  32   a  and  32   b  penetrate the bolt support section  14  in its thickness direction and are arranged in the lateral direction of the casing main body  12 . The one bolt receiving aperture  32   a  is a circular shape in cross section while the other bolt receiving aperture  32   b  is a substantially rectangular shape in cross section. 
         [0028]    A peripheral wall  34  protrudes from the upper surface  28  of the bolt support section  14 . The peripheral wall  34  includes a partition wall  36  that partitions the bolt support section  14  and the adjacent fuse mounting sections  26  extending in the lateral direction of the casing main body  12 , and a pair of longitudinal walls  38   a  and  38   b  that extend in parallel with each other in the longitudinal direction (right and left directions in  FIG. 5 ) of the casing main body  12 . Thus, the peripheral wall  34  surrounds the two bolt receiving apertures  32   a  and  32   b  from three sides. 
         [0029]    The one longitudinal wall  38   a  is provided on a proximal end with an inserting slit  40  that penetrates the wall  38   a  in its thickness direction. The other longitudinal wall  38   b  is provided on a proximal end with a latch recess  42  that is open in an inner side surface. 
         [0030]    The longitudinal walls  38   a  and  38   b  extend to an upper surface  46  of an electrical cable support section  44  that extends toward the one end (a right side in  FIG. 2 ) in the longitudinal direction of the casing main body  12 . The upper surface  46  of the electrical cable support section  44  is disposed over the upper surface  28  of the bolt support section  14 . Thus, a stepped portion  48  is formed between the bolt support section  14  and the electrical cable support section  44 . 
         [0031]    The bolt support section  14  is provided on the upper surface  28  with a partition wall  50 . The partition wall  50  extends from an inner side surface of the partition wall  36  in parallel to the longitudinal walls  38   a  and  38   b  to partition the two bolt receiving apertures  32   a  and  32   b.  The partition wall  50  is provided on a proximal end portion with an inserting slit  52  that penetrates the wall  50  in its thickness direction. 
         [0032]    The partition wall  50  extends to the upper surface  46  of the electrical cable support section  44 , as is the case with the longitudinal walls  38   a  and  38   b.  Thus, electrical cable containing portions  54   a  and  54   b  that extend in the longitudinal direction of the casing main body  12  are provided in the electrical cable support section  44  between the one longitudinal wall  38   a  and the partition wall  50  and between the other longitudinal wall  38   b  and the partition wall  50 . 
         [0033]    Stopper projections  56  and  56  that protrude inward in the electrical cable containing portions  54   a  and  54   b  are provided on the pair of longitudinal walls  38   a  and  38   b  and the partition wall  50  and on portions that protrude to the upper surface  46  of the electrical cable support section  44 . Thus, external terminals  20   a  and  20   b  are engaged with the stopper projections  56  in the longitudinal direction of the casing main body  12 . Consequently, it is possible to prevent electrical cables  18   a  and  18   b  from being disengaged from the electrical cable containing portions  54   a  and  54   b  in the longitudinal direction of the casing main body  12 . 
         [0034]    A connecting plate  58  is mounted on the upper surface  28  of the bolt support section  14 . The connecting plate  58  is made of a metallic material such as oxygen-free copper having a high electrical conductivity and is formed into a rectangular thick flat plate-like configuration, as a whole. Two bolt inserting apertures  60   a  and  60   b  are provided in the connecting plate  58  and arranged side by side in its longitudinal direction. A latch projection  62  is provided on an end of the connecting plate  58  in the longitudinal direction so as to protrude outward in the longitudinal direction. 
         [0035]    The bolt containing section  14  is provided in the other surface in the thickness direction with bolt containing apertures  64 . The bolt containing apertures  64  are disposed on the same central axes as those of the bolt receiving apertures  32   a  and  32   b,  have substantially rectangular shapes in cross section, and extend straightly in the height direction of the casing main body  12 . Ends of the bolt containing apertures  64  are connected to the bolt receiving apertures  32   a  and  32   b.  Each bolt containing aperture  64  is provided on a pair of opposed side surfaces in the longitudinal direction of the casing main body  12  with an engaging projection  66 , respectively. 
         [0036]    The connecting bolts  16   a  and  16   b  to be attached to the bolt support section  14  include rectangular block-like head portions  68  and shaft portions  70  protruding from seats of the head portions  68 . Each shaft portion  70  is provided on a proximal end with a proximal end side projection  72  that has a larger diameter than that of the shaft portion  70 . 
         [0037]    Bolt covers  74  and  74  made of synthetic resin are mounted on the connecting bolts  16   a  and  16   b,  respectively. Each bolt cover  74  includes a rectangular tubular wall  76  and a bottom wall  78  integrated with an end of the tubular wall  76  and is formed into a reversed rectangular box-like configuration provided with a recess that is open downward. 
         [0038]    Such bolt covers  74  are mounted on the connecting bolts  16   a  and  16   b . Under this condition, the head portions  68  are contained in the tubular walls  76  of the bolt covers  74  and the shaft portions  70  pass through inserting apertures  80  in the bottom walls  78  to protrude outward from the bolt covers  74 . 
         [0039]    If the head portion  68  turns about its central axis in the tubular wall  76 , the head portion  68  will contact with the tubular wall  76 . Thus, it is possible to restrain the head portion  68  from turning about its central axis in the tubular wall  76 . 
         [0040]    Each head portion  68  is contained in the tubular wall  76  with the head portion  68  passing over the latch projection piece  82  that is permitted to be elastically deformed in a direction where a projecting height of the piece  82  from an inner periphery of the tubular wall  76  becomes small and with the head portion  68  being disposed between the latch projection piece  82  and the bottom wall  78 . Thus, it is possible to prevent the head portion  68  from being disengaged from the tubular wall  76 . 
         [0041]    When the head portion  68  is engaged with the latch projection piece  82 , a clearance is defined between the head portion  68  and the bottom wall  78 . Each of the connecting bolts  16   a  and  16   b  can move in an axial direction with respect to each bolt cover  74  by a distance corresponding to the clearance. When the head portion  68  contacts with the bottom wall  78 , a distal end surface of the proximal end side projection  72  is disposed at a position higher than a projecting end surface of a collar  84  that protrudes from the bottom wall  78 . 
         [0042]    A bus bar  90  is incorporated in the casing main body  12  so that the bus bar  90  constitutes internal circuits for distributing an electrical power from a battery. The electrical power is supplied through a plurality of fuses installed in the fuse mounting sections  26  to electrical equipments for an audio device, a tow hitch, a back door, and the like that are installed in a rear part of the vehicle body. The bus bar  90  is formed by suitably bending a rectangular flat plate-like copper. 
         [0043]    The bus bar  90  is provided with bus bar terminal portions  92 . Each bus bar terminal portion  92  is formed into a rectangular flat plate-like configuration and is provided in a central part with a bolt inserting aperture  94 . 
         [0044]    As shown in  FIG. 6A , the bus bar  90  is incorporated in the casing main body  12  from a lower side before the connecting bolts  16   a  and  16   b  are attached to the bolt support section  14 . Under this condition, the bus bar terminal portions  92  are disposed in the bolt receiving apertures  32   b  and upper surfaces of the terminal portions  92  are disposed at the same level as the upper surface  28  of the bolt support section  14 . 
         [0045]    As shown in  FIG. 6B , after the bus bar  90  is incorporated in the casing main body  12 , the connecting plate  58  is inserted into the slits  40  and  52  at a longitudinal side end on which the latch projection  62  is provided and the connecting plate  58  is disposed on the upper surface  28  of the bolt support section  14 . Under this condition, the connecting plate  58  is clamped between the partition wall  36  and the stepped portion  48  and the longitudinal end side of the plate  58  is superimposed on the bus bar terminal portions  92 . 
         [0046]    The latch projection  62  is inserted into and engaged with the latch recess  42 . Thus, the connecting plate  58  is restrained from moving in the lateral direction. That is, the latch projection  62  and latch recess  42  constitute means for restraining displacement of the connecting plate  58 . 
         [0047]    The bolt inserting aperture  60   a  is disposed on the substantially same central axis as the bolt receiving aperture  32   a,  while the bolt receiving aperture  60   b  is disposed on the substantially same central axis as the bolt receiving aperture  32   b.    
         [0048]    As shown in  FIG. 6C , when the connecting plate  58  is disposed on the upper surface  28  of the bolt support section  14 , the connecting bolts  16   a  and  16   b  are inserted into the bolt containing apertures  64  and  64 . Thus, the engaging projection  86  provided on the outer surface of each bolt cover  74  is engaged with the engaging projection  66  provided on the inner periphery of each bolt containing aperture  64  and the connecting bolts  16   a  and  16   b  are attached to the bolt support section  14  so that the bolt cover  74  is prevented from being disengaged from the bolt containing aperture  64 . Thus, the connecting bolts  16   a  and  16   b  are attached to the bolt support section  14 . Each bolt cover  74  is restrained from turning about the central axis in each bolt containing aperture  64  by contact of the bolt cover  74  with the inner periphery of the bolt containing aperture  64 . Thus, the connecting bolts  16   a  and  16   b  are also restrained from turning about their central axes in the bolt containing apertures  64 . That is, the bolt covers  74  and bolt containing apertures  64  constitute means for holding the bolts. 
         [0049]    The tubular wall  76  is elastically deformed inward and the engaging projection  86  passes over the engaging projection  66 , when the connecting bolts  16   a  and  16   b  are attached to the bolt support section  14 . Then, the engaging projection  86  can be engaged with the engaging projection  66 . The engaging projection  86  protrudes from a bottom surface of a recess provided in the outer periphery of the bolt cover  74 . 
         [0050]    When the engaging projection  86  is engaged with the engaging projection  66 , a clearance is defined between the bolt cover  74  and the bolt support section  14 . The bolt cover  74  can move in the axial direction with respect to the bolt containing aperture  64  by a distance corresponding to the clearance. 
         [0051]    The collar portions  84  of the bolt covers  74  are inserted into the bolt receiving apertures  32   a  and  32   b  in the bolt support section  14 . Thus, the shaft portions  70  of the connecting bolts  16   a  and  16   b  protrude from the upper surface  28  of the bolt support section  14 . In result, the shaft portion  70  of the connecting bolt  16   a  is inserted into the bolt inserting aperture  94  in the bus bar terminal portion  92  and the bolt inserting aperture  60   b  in the connecting plate  58 . The shaft portion  70  of the connecting bolt  16   b  is inserted into the bolt inserting aperture  60   a  in the connecting plate  58 . 
         [0052]    The external terminals  20   a  and  20   b  are incorporated on the connecting bolts  16   a  and  16   b.  Under this condition, a nut  96  is screwed on and fastened to each shaft portion  70 . Thus, the external terminal  20   a  and  20   b  are secured to the connecting bolts  16   a  and  16   b.    
         [0053]    When the connecting bolts  16   a  and  16   b  are displaced toward the nuts  96  and  96  by a threading action between the nuts  96  and the shaft portions  70 , the distal end surfaces of the proximal end side projections  72  protrude from the projecting end surfaces of the collar portions  84 . If each nut  96  is further fastened from this condition, the bolt cover  74  also moves to the nut  96 . 
         [0054]    Thus, the external terminal  20   a,  connecting plate  58 , bus bar terminal portion  92  are fastened directly among the nut  96 , connecting bolt  16   a,  and proximal end side projection  72 , and the external terminal  20   a,  connecting plate  58 , and bus bar terminal portion  92  are electrically connected to and secured to one another. The external terminal  20   b  and connecting plate  58  are fastened directly between the nut  96  and the proximal end side projection  72  of the connecting bolt  16   b,  and the external terminal  20   b  and connecting plate  58  are electrically connected to and secured to each other strongly. 
         [0055]    Consequently, the electrical power that is supplied from the battery through the electrical cable  18   a  to the fuse box  10  is supplied through the bus bar  90  to various kinds of external electrical equipments with an excellent current conductive efficiency. 
         [0056]    Since the external terminal  20   a  and  20   b  are connected through the connecting plate  58  to each other, the electrical power supplied from the battery through the electrical cable  18   a  can be supplied through the electrical cable  18   b  to the electrical junction box installed in the front part of the vehicle body with the excellent current conductive efficiency. 
         [0057]    The electrical cable  18   a  is disposed in the electrical cable containing portion  54   b  with the electrical cable  18   a  being attached to the connecting bolt  16   a.  The electrical cable  18   b  is disposed in the electrical cable containing portion  54   a  with the electrical cable  18   b  being attached to the connecting bolt  16   b.  Thus, the electrical cables  18   a  and  18   b  are attached to the connecting bolts  16   a  and  16   b  with the electrical cables  18   a  and  18   b  extending in a direction parallel to the longitudinal direction of the casing main body  12 . 
         [0058]    In the fuse box  10  described above, not only the peripheral wall  34  but also the partition wall  50  protrude from the bolt support section  14 . Thus, it is possible to enhance a reinforcement effect for the bolt support section  14 . 
         [0059]    Before the shaft portions  70  and  70  of the connecting bolts  16   a  and  16   b  are inserted into the bolt inserting apertures  60   b  and  60   a  in the connecting plate  58 , the connecting plate  58  is inserted into the inserting slits  40  and  52  and is disposed on the upper surface  28  of the bolt support section  14 . Consequently, although the bolt support section  14  is provided with the partition wall  50 , the partition wall  50  does not interfere with the two connecting bolts  16   a  and  16   b  when the connecting plate  58  are mounted on the connecting bolts  16   a  and  16   b.    
         [0060]    Each bolt cover  74  is kept to be contained in each bolt containing aperture  64 . Thus, it is possible to maintain the connecting bolts  16   a  and  16   b  to be inserted in the bolt inserting apertures  60   b  and  60   a.    
         [0061]    The connecting plate  58  and bus bar terminals  92  are directly superimposed on each other. Thus, it is possible to enhance an electrical current conductive efficiency from the connecting plate  58  to the bus bar  90 . 
         [0062]    Particularly, since the connecting bolts  16   a  and  16   b  are displaced in the axial direction upon fastening of the nuts  96 , even if any clearance is defined between the bus bar terminal portions  92  and the connecting plate  58  on account of low accuracy in assembling of the bus bar  90  in the casing main body  12 , it is possible to directly superimpose the connecting plate  58  and bus bar terminal portions  92  on one another. Consequently, it is possible to enhance reliability in connection between the connecting plate  58  and the bus bar  90 . 
         [0063]    Since the latch projection  62  of the connecting plate  58  is engaged with the latch recess  42  in the peripheral wall  34 , it is possible to prevent the connecting plate  58  from moving in the longitudinal direction of the casing main body  12 , before the connecting bolts  16   a  and  16   b  are attached to the casing main body  12 . Thus, it is possible to facilitate to insert the shaft portions  70  and  70  of the connecting bolts  16   a  and  16   b  into the bolt inserting apertures  60   b  and  60   a  in the connecting plate  58 . 
         [0064]    Since the connecting bolts  16   a  and  16   b  are not secured to the casing main body  12  previously by means of insert molding or press-fitting, it is possible to incorporate the bus bar  90  in the casing main body  12  from the lower side of the main body  12 . 
         [0065]    The connecting plate  58  is disposed on the upper surface  28  of the bolt support section  14  with the connecting plate  58  being inserted in the slit  52  in the proximal end of the partition wall  50 . Thus, even if the connecting plate  58  floats up from the upper surface  28  of the bolt support section, when the casing main body  12  is turned upside down, the connecting plate  58  contacts with the partition wall  50 , thereby preventing the connecting plate  58  from falling down from the casing main body  12 . In result, it is possible to enhance flexibility in a work for attaching the connecting bolts  16   a  and  16   b  to the bolt support section  14 . 
         [0066]    Although the present invention is described in the embodiments in detail, it should be noted that the present invention is not limited to the above embodiments. For example, in the above embodiments, the head portions  68  and  68  of the connecting bolts  16   a  and  16   b  may be disposed directly on the engaging projections  66  provided on the inner periphery of the bolt containing apertures  64  and  64 .