Abstract:
A first housing is formed with a cavity adapted to receive both of a second housing having a first length and provided with a first fuse, and a third housing having a second length smaller than the first length and provided with a second fuse. The cavity has a bottom. A pair of terminals are extended from the bottom of cavity so as to have a third length. The terminals are adapted to be fitted with both of the first fuse and the second fuse. At least one spacer having a predetermined thickness smaller than the third length is removably disposed on the bottom of cavity, at least in a case where the third housing is received in the cavity.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a cavity structure of an electric junction box in which an automotive fuse is mounted. 
     FIG. 4 shows a related-art electric junction box in which an automotive fuse is mounted. 
     In the cavity  40  shown in FIG. 4, a pair of tab (male) terminals  43  and  44 , projecting from a bottom plate  42 , are disposed within a housing receiving portion  41  having four side walls, and an upper end portion of the housing receiving portion  41  serves as a cavity opening  45 . The pair of tab terminals  43  and  44  are connected serially to a circuit of an automotive electrical equipment. 
     Examples of automotive fuses to be mounted in such a cavity  40  are shown in FIGS. 5 and 6. 
     An automotive fuse  50 , shown in FIG. 5, is a long-body plug-in fuse, and a cover  52  is provided at an upper end of a housing body  51  of a square tubular shape, and an opening  53  is formed at a lower end of the housing body  51 . A pair of tab-receiving (female) terminals  54  and  55  are provided within the housing body  51 , and are disposed relatively remote from the opening  53 , and a fusible element  56  is integrally connected to upper ends of the tab-receiving terminals  54  and  55 . The cover  52  is locked to the housing body  51  by a pair of locking pieces (not shown). 
     An automotive fuse  60 , shown in FIG. 6, is a short-body plug-in fuse, and a cover  62  is provided at an upper end of a housing body  61  of a square tubular shape, and an opening  63  is formed at a lower end of the housing body  61 . A pair of tab-receiving (female) terminals  64  and  65  are provided within the housing body  61 , and are disposed relatively close to the opening  63 , and a fusible element  66  is integrally connected to upper ends of the tab-receiving terminals  64  and  65 . 
     A pair of elastic locking pieces  62   a  are formed respectively at opposite ends of the cover  62 , and these locking pieces  62   a  can be locked respectively to a pair of retaining projections  61   a  formed respectively at corresponding portions of the housing body  61 . 
     The opening  53 ,  63  of the automotive fuse  50 ,  60  is located in registry with the cavity opening  45 , and the housing body  51 ,  61  is inserted into the housing receiving portion  41  until the opening  53 ,  63  is brought into contact with the bottom plate  42 , so that the tab-receiving terminals  54  and  55  ( 64  and  65 ) are electrically connected to the tab terminals  43  and  44 , respectively. 
     When a large current flows in the circuit, for example, as a result of development of seizure in the electrical equipment such as a motor, the fusible element  56 ,  66  melts to break the circuit so as to prevent an excess large current from flowing in the circuit, thus protecting the circuit. 
     The automotive fuses  50  and  60  are disclosed, for example, in Japanese Patent Publication No. 2001-325875A. 
     Usually, fuse cavities, together with switching devices (such as relays) are provided at a junction box or a specially-designed fuse box, and therefore it is not desired to form the fuse cavities into various shapes, and the fuse cavities are molded into a standardized single shape. Therefore, it has been desired that the cavity  40  should have the housing receiving portion  41  of a common construction for use with both of the long-body automotive fuse  50  and the short-body automotive fuse  60 . 
     When the long-body automotive fuse  50  is mounted in the cavity  40 , the housing body  51  is received within the housing receiving portion  41 , with the distal ends of the tab terminals  43  and  44  considerably spaced from the fusible element  56  (see FIG.  5 ). 
     However, when the short-body automotive fuse  40  is mounted in the cavity, the housing body  61  is received within the housing receiving portion  41 , with the distal ends of the tab terminals  43  and  44  disposed close to the fusible element  66 , and therefore the tab terminals  43  and  44  are liable to interfere with the fusible element  66 . When the tab terminals  43  and  44  interfered with the fusible element  66 , there is anxiety that the housing body  61  could not be surely inserted into the housing receiving portion  41 . 
     When the tab terminals  43  and  44  are designed such that the length of projecting of the tab terminals  43  and  44  within the housing receiving portion  41  is reduced, the above anxiety with the short-body automotive fuse  60  is overcome. However, since the length of projecting of the tab terminals  43  and  44  are short, the area of contact between each of the tab terminals  43  and  44  and the corresponding tab-receiving terminal  64 ,  65  of the long-body automotive fuse  60  is reduced, the electrical connection between the two would be unstable. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention is to provide a cavity structure of an electric junction box which has an enhanced general-purpose ability for use with various fuses. 
     In order to achieve the above object, according to the invention, there is provided an electric junction box, comprising: 
     a first housing, formed with a cavity adapted to receive both of a second housing having a first length and provided with a first fuse, and a third housing having a second length smaller than the first length and provided with a second fuse, the cavity having a bottom; 
     a pair of terminals, extending from the bottom of cavity so as to have a third length, and adapted to be fitted with both of the first fuse and the second fuse; and 
     at least one spacer, having a predetermined thickness smaller than the third length and removably disposed on the bottom of cavity, at least in a case where the third housing is received in the cavity. 
     Here, it is preferable that the predetermined thickness is determined so as to adjust a fitting amount of the third housing into the cavity. 
     It is also preferable that the predetermined thickness is determined so as to adjust a length of the terminals projected from a top face of the spacer. 
     It is also preferable that the predetermined thickness is determined so as to adjust a depth of the cavity. 
     In the above configuration, in a case where the terminals interfere with the fuse provided in the mating housing, the spacer is disposed so as to reduce the fitting amount of the mating housing into the cavity (the projected amount of the terminal from the top face of the spacer, or the depth of the cavity). On the other hand, in a case where the terminals do not interfere with the fuse, the spacer is not disposed. 
     Therefore, the different housings can be surely mounted in the first housing of the same construction, and there can be obtained the electric junction box having an enhanced general-purpose ability for use with the various fuses. 
     Preferably, an outline of the spacer is substantially identical with an outline of the bottom of the cavity. 
     It is also preferable that the spacer is formed with a pair of through holes through which the terminals are inserted. 
     In such configuration, since the terminals are prevented from being bent, the fuse is prevented from being displaced out of position. 
     Preferably, a color of the spacer is different from a color of the first housing. 
     In such a configuration, those cavities, each having the spacer mounted therein, can be easily distinguished from those cavities each having no spacer, and the erroneous mounting of the fuse can be surely prevented. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above objects and advantages of the present invention will become more apparent by describing in detail preferred exemplary embodiments thereof with reference to the accompanying drawings, wherein: 
     FIG. 1 is a partly-broken perspective view of a cavity structure of an electric junction box according to one embodiment of the invention; 
     FIG. 2 is a cross-sectional view of the cavity structure in which a short-body automotive fuse is mounted; 
     FIG. 3 is a cross-sectional view of the cavity structure in which a long-body automotive fuse is mounted; 
     FIG. 4 is a partly-broken perspective view of a related-art cavity structure of an electric junction box; 
     FIG. 5 is a cross-sectional view of the related-art cavity structure in which a long-body automotive fuse is mounted; and 
     FIG. 6 is a cross-sectional view of the related-art cavity structure in which a short-body automotive fuse is mounted. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     One preferred embodiment of a cavity structure of an electric junction box of the invention will now be described in detail with reference to the accompanying drawings. 
     As shown in FIGS. 1 and 2, the electrical junction box has a first housing body  7  having a cavity  10  for receiving a second housing body  31  of fuse  30  and a third housing body  21  of fuse  20 , as discussed below. The cavity  10  of the electric junction box of this embodiment includes a housing receiving portion  11  having a cavity opening  12 , a bottom plate  13 , a pair of tab (male) terminals  14  and  15 , and a spacer  16 . A plurality of cavities  10  are provided on the electric junction box such as a relay box. 
     The housing receiving portion  11  is defined by inner surfaces of four side plates  17   a ,  17   b ,  18   a  and  18   b , and an upper end portion of this housing receiving portion serves as the cavity opening  12 . The bottom plate  13  is integrally connected to lower ends of the side plates  17   a ,  17   b ,  18   a  and  18   b.    
     The pair of tab terminals  14  and  15  are provided generally at a central portion of the bottom plate  13  in a juxtaposed manner, and project toward the cavity opening  12 . The tab terminals  14  and  15  extend through the bottom plate  13  at their lower end portions, and are connected serially at their lower ends to an upstream side of a circuit of an electrical equipment mounted on a vehicle body. 
     The spacer  16  has substantially the same size as that of the bottom plate  13 , and has a predetermined thickness t1. 
     The spacer  16  is made of an insulative material such as rubber or a synthetic resin, and is molded into an integral construction. 
     A pair of through holes  16   a  and  16   b  for the passage of the pair of tab terminals  14  and  15  are formed through the spacer  16 . 
     The spacer  16  is inserted into the housing receiving portion  11  through the cavity opening  12 , and the tab terminals  14  and  15  are passed respectively through the through holes  16   a  and  16   b , so that this spacer  16  is laid on an upper surface of the bottom plate  13  over an entire area thereof. Thus, the spacer is removably mounted in the cavity  10 . By doing so, an adjustment is made to decrease the depth of the housing receiving portion  11 , that is, the amount of insertion of the fuse. 
     When the spacer  16  is not mounted, the depth of the housing receiving portion  11 , that is, the amount of insertion of the fuse, does not need to be adjusted. In other words, by mounting the spacer  16 , the amount of projecting of the tab terminals  14  and  15  beyond the upper surface of the bottom plate  13  can be adjusted into a smaller value. By not mounting the spacer  16 , the amount of projecting of the tab terminals  14  and  15  beyond the upper surface of the bottom plate  13  can be adjusted into a maximum value. 
     When a short-body automotive fuse  20  is to be mounted in the cavity  10  of this embodiment, the spacer  16  is mounted in the cavity as shown in FIG.  2 . In the short-body automotive fuse  20 , a cover  22  is provided at an upper end of the housing body  21  of a square tubular shape (the width and height of this housing body are generally equal to each other), and an opening  23  is formed at a lower end of the housing body  21 . 
     A pair of tab-receiving (female) terminals  24  and  25  are provided within the housing body  21 , and are disposed relatively close to the opening  23 , and a fusible element  26  is integrally connected to upper ends of the tab-receiving terminals  24  and  25 . 
     A stopper  22   a  for abutting against the upper end of the housing receiving portion  11  is formed at and projects from a peripheral edge of the cover  22 . A pair of elastic locking pieces  22   b  are formed respectively at opposite ends of the cover  22 , and these locking pieces  22   b  can be locked respectively to a pair of retaining projections  21   a  formed respectively at corresponding portions of the housing body  21 . This stopper may be formed at the housing body  21  side. 
     The opening  23  of the automotive fuse  20  is located in registry with the cavity opening  12  of the cavity  10 , and the housing body  21  is inserted into the housing receiving portion  11  until the opening  23  is brought into contact with the spacer  16 . As a result, the automotive fuse is mounted in the cavity  10  in such a manner that the tab-receiving terminals  24  and  25  are electrically connected to the tab terminals  14  and  15 , respectively. At this time, the depth of the housing receiving portion  11  is adjusted into a smaller value by the spacer  16 , so that the automotive fuse  20  can be surely mounted while the tab terminals  14  and  15  do not interfere with the fusible element  26 . 
     For mounting the long-body automotive fuse  30 , this long-body automotive fuse  30  is mounted directly in the cavity without the use of the spacer  16  as shown in FIG.  3 . In the long-body automotive fuse  30 , a cover  32  is provided at an upper end of the housing body  31  of a square tubular shape (the height of this housing body is larger than its width), and an opening  33  is formed at a lower end of the housing body  31 . 
     A pair of tab-receiving (female) terminals  34  and  35  are provided within the housing body  31 , and are disposed relatively remote from the opening  33 , and a fusible element  36  is integrally connected to upper ends of the tab-receiving terminals  34  and  35 . The cover  32  is locked to the housing body  31  by a pair of locking pieces (not shown). 
     The opening  33  of the automotive fuse  30  is located in registry with the cavity opening  12  of the cavity  10 , and the housing body  31  is inserted into the housing receiving portion  11  until the opening  33  is brought into contact with the bottom plate  13 . As a result, the automotive fuse is mounted in the cavity  10  in such a manner that the tab-receiving terminals  34  and  35  are electrically connected to the tab terminals  14  and  15 , respectively. At this time, the tab terminals  14  and  15  will not interfere with the fusible element  36  since the depth of the housing receiving portion  11  of the cavity  10  is predetermined in accordance with the long-body automotive fuse. 
     According to the above configuration, it is not necessary to change the overall configuration of the cavity  10 , depending on the type of the fuse  20 ,  30 . Only what is to do is forming and mounting the spacer  16  in accordance with the sizes of the automotive fuses. 
     In addition, since the spacer  16  has the same outer shape as that of the bottom plate  13  of the housing receiving portion  11 , the tab terminals  14  and  15  are prevented from being bent, so that the fuse  20 ,  30  is prevented from being displaced out of position. 
     Furthermore, since the spacer  16  is mounted in the cavity  10  such that it can be recognized with the eyes, it is possible to avoid erroneous mounting of the fuse in such a way the long-body automotive fuse  30  is mounted in the cavity  10  in which the spacer  16 . 
     In the cavity structure of the electric junction box of the invention is not limited to the above embodiment, and suitable modifications and improvements can be made. 
     For example, instead of using the spacer having the same outer shape as that of the bottom plate, there may be used a spacer having an elliptical or an oval shape covering the tab terminals. 
     Preferably, the spacer has a different color from that of the cavity. In this case, those cavities, each having the spacer mounted therein, can be easily distinguished from those cavities each having no spacer, and the erroneous mounting of the fuse can be surely prevented. 
     The thickness of the spacer is not always limited to the value determined in accordance with the short-body and long-body automotive fuses, but this thickness can be selected in accordance with the structure of other fuses used in the specified vehicle. Also, the disposed number of the spacer may be two or more. Therefore, by preparing several kinds of spacers of different thicknesses or disposing plural spacers, the cavity of the same construction can meet three or more kinds (types) of automotive fuses. 
     The tab terminals as well as the tab-receiving terminals are not limited to two poles, but can be applied to a multi-pole (four poles or six or more poles) arrangement in which pairs of poles are juxtaposed to each other.