Abstract:
Fuse bus bars in a fuse module are provided with press contact terminals that are connected to terminals of each fuse and are disposed closely in parallel with each other. If there are some circuits to be connected and the other circuits to be divided in all circuit specifications in the different kinds of and same kind of automobile vehicles that mount junction boxes, the fuse bus bars constituting the circuits are integrally connected by bridging portions. If the circuits are required to be divided in accordance with the circuit specification of the automobile vehicle mounting the fuse bus bars, an alteration of circuit can be carried out by cutting off the bridging portion.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention relates to a junction box and more particularly relates to a junction box that is connected to a wire harness for an automobile vehicle and can easily change a circuit design. The present application claims priority to Japanese Application No. 2002-325472 filed on Nov. 8, 2002. 
     2. Description of Prior Art 
     Recently, as electrical components installed on an automobile vehicle have suddenly increased, circuits to be contained in a junction box have suddenly increased. In order to form branched circuits at a high density, the number of parts has extremely increased. This requires very many assembling steps. 
     The present applicant has proposed a junction box (Japanese Patent Public Disclosure 2001-359227), as shown in  FIG. 7 , in order to form a thin type junction box, to easily change a circuit design and to reduce assembling steps. 
     For convenience of explanation, a prior art junction box will be described by referring to  FIGS. 7 and 8 .  FIG. 7  is an exploded perspective view of a conventional junction box.  FIG. 8  is a perspective view of a part of a conventional connector module, illustrating problems in the module. 
     In a junction box  1 , a connector connection circuit section (base circuit section), a fuse connection circuit section, and a relay connecting circuit section are divided into a connector module  2 , a fuse module  3 , and a relay module  4 . These modules  2 ,  3 , and  4  are assembled in a casing including an upper casing member  5  and a lower casing member  6 . 
     In the connector module  2 , bus bars  7  punched out into a desired circuit pattern from a sheet of a conductive metal plate are disposed on an insulation board  8  and a plurality of combinations of the bus bars  7  and insulation boards  8  are laminated on one another so that ends of the bus bars  7  project from peripheral edges of the insulation boards  8 . In the fuse module  3  and relay module  4 , bus bars  3   b  and  4   b  are secured to base plates  3   a  and  4   a , respectively so that ends of the bus bars  3   b  and  4   b  project from peripheral edges of the base plates  3   a  and  4   a . The ends of the bus bars  3   b  and  4   b  are connected to the ends of the bus bars  7  of the connector module  2  to form an electrical connection. 
     In the case where the junction box is divided into the connector module, fuse module, and relay module, the connector connection circuit, fuse connection circuit, and relay connecting circuit are also divided. Accordingly, only the corresponding module is changed, if a specification in the connector circuit, the fuse circuit, or the relay circuit is changed. Consequently, it is possible to easily comply with an alteration of specification. 
     Since the division of the circuits can eliminate overlap of tabs of the bus bars and avoid multiple layers of the bus bars, it is possible to reduce a thickness of the junction box. Furthermore, since an arrangement of the bus bars can be simplified, it is possible to reduce an area of the bus bars and suppress an increase of an area of the junction box. 
     However, in the case of changing circuits in the junction box  1 , although only the corresponding modules  5 ,  6 , and  8  are altered and a whole of the junction box  1  is not altered, at least one of the modules  5 ,  6 , and  8  must be newly formed. 
     Furthermore, in the case of changing the circuits in accordance with a specification of an automobile vehicle mounting the junction box, it is necessary to prepare a certain kind of module every specification. This will increase the number of kinds of parts and the load of controlling the number of parts. 
     In order to overcome the above problems, as shown in  FIG. 8 , bus bars  7   a - 1  and  7   a - 2  in the connector module  2  are connected to each other by a bridging portion  7   a - 3  and the bridging portion  7   a - 3  may be either cut off or retained in accordance with the specification of an automobile vehicle to comply with an alteration of circuit design. 
     However, it is necessary to dispose the bus bars  7   a   1  and  7   a - 2  adjacent to each other in order to connect them by the bridging portion  7   a - 3 . It is impossible to provide the bridging portion between a bus bar  7   b  and a bus bar  7   c  on different layers due to their structures. On the other hand, it is difficult to design the bus bars on a single layer to set the bridging portions. Even if such design is carried out, the number of stacked layers including the bus bars  7  and insulation boards  8  must be increased. This involves a problem of an increase in cost. Accordingly, there are limitations in the number of the patterns to provide changeable circuit patterns by selectively cutting off the bridging portions in the stacked circuits including the insulation boards  8  and bus bars  7   a  to  7   b.    
     SUMMARY OF THE INVENTION 
     In view of the above problem, an object of the present invention is to provide a junction box that can easily alter a circuit design without increasing the number of stacked layer including the bus bars and insulation boards. 
     In order to solve the above problems, the present invention is directed to a junction box wherein a connector connection circuit section and a fuse connection circuit section adapted to be contained in the junction box are divided into a connector module and a fuse module separately and circuits in the modules are connected to one another. The connector module includes stacked circuit boards, each of which has a first insulation board and bus bars secured to the first insulation board. The fuse module includes a second insulation board and fuse bus bars that are secured to the second insulation board and are connected to terminals of each fuse. The fuse bus bars in the fuse module are provided with press contact terminals that are connected to terminals of each fuse and are disposed closely in parallel with each other. If there are some circuits to be connected and the other circuits to be divided in all circuit specifications in the different kinds of and same kind of automobile vehicles each of which mounts a junction box, the fuse bus bars constituting the circuits are integrally connected by bridging portions. If the circuits are required to be divided in accordance with the circuit specification of the automobile vehicle mounting the fuse bus bars, an alteration of circuit can be carried out by cutting off the bridging portions. 
     According to the above structure, it is possible to realize a plurality of circuit patterns by utilizing only a single kind of a fuse bus bar either by retaining the bridging portions of the fuse bus bars or by cutting off the bridging portions. Consequently, it is not necessary to produce a new module together with a new junction box upon alteration of circuit design. This will reduce kinds of parts and the load of controlling product numbers and lower a cost in parts. 
     In addition, the bridging portions for dividing the circuits in the present invention are provided on the fuse bus bars in the fuse module to which input and output sections of circuits are connected in parallel. The bus bars to be connected by the bridging portions are disposed in parallel and are not dispersed in different layers in comparison with a circuit that utilizes the connector module. This will make it easy to set the bridging portions. It is also possible to provide more circuit patterns in compliance with an alteration of specification. 
     Even if a plurality of bridging portions for dividing the circuits are set in accordance with the specification of an automobile vehicle, the number of stacked layers of the insulation boards and bus bars in the connector module is not increased, an arrangement density of bus bars can be enhanced, and an increase in cost and upsizing of a junction box can be prevented. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features of the present invention believed to be novel and the elements characteristic of the present invention are set forth with particularity in the appended claims. The figures are for illustration purposes only and are not drawn to scale. The invention itself, however, both as to organization and method of operation, may best be understood by reference to the detailed description which follows taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is an exploded perspective view of an embodiment of a junction box in accordance with the present invention; 
         FIG. 2  is a developed view of fuse bus bars for a fuse module; 
         FIG. 3  is a schematic diagram of a circuit; 
         FIGS. 4A  to  4 F are schematic diagrams illustrating various circuit patterns; 
         FIG. 5  is an explanatory view illustrating patterns of bridging portions to be divided; 
         FIG. 6  is an exploded perspective view of a fuse module, illustrating a connection between a fuse and a fuse bus bar; 
         FIG. 7  is an exploded perspective view of a conventional junction box; and 
         FIG. 8  is a perspective view of a part of a conventional connector module, illustrating problems in the module. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In describing the preferred embodiment of the present invention, reference will be made herein to  FIGS. 1  to  6  of the drawings in which like numerals refer to like features of the invention. Features of the invention are not necessarily shown to scale in the drawings. 
     Referring now to  FIGS. 1  to  6 , an embodiment of a junction box in accordance with the present invention will be explained below. 
       FIG. 1  is an exploded perspective view of a junction box  10  to be connected to a wire harness for an automobile vehicle. 
     In  FIG. 1 , the junction box  10  includes an upper casing member  11 , an electronic control unit (ECU)  12 , an insulation board  13 , a connector module  14 , a relay module  15 , a fuse module  16 , and a fuse casing  17 , and a lower casing member  18 . 
     The relay module  15 , connector module  14 , insulation board  13 , and electronic control unit  12  are arranged in a vertical direction (in  FIG. 1 ) on the lower casing member  18  in order. The upper casing member  11  is mounted on the lower casing member  18 . The upper casing member  11  is provided in a short side of a peripheral wall thereof with a side opening  11   a . The fuse module  16  is attached to the side opening  11   a  in a horizontal direction (in FIG.  1 ). 
     The upper casing member  11  is provided on an inner surface of each long side thereof with latch portions (not shown) that are adapted to be locked on the lower casing member  18 . The lower casing member  18  is provided with locking pawls  18   c  that engage the latch portions on the upper casing member  11  so that the upper casing member  11  is coupled to and locked on the lower casing member  18 . The electronic control unit  12 , insulation board  13 , connector module  14 , and relay module  15  are contained in the interior defined by the upper and lower casing members  11  and  18 . 
     The lower casing member  18  is also provided with a plurality of connector receiving sections  18   a  to be coupled to the connector module  14  and a plurality of relay receiving sections  18   b  to be coupled to the relay module  15 . 
     The fuse module  16  is attached to the side opening  11   a  so as to be disposed on a side surface of the connector module  14 . The fuse module  16  contains an insulation board  24  to which fuse bus bars  23  ( 25  to  28 ) are secured. The fuse bus bars  23  ( 25  to  28 ) are connected to a pair of terminals  30   a  and  30   b  of each of fuses  30  (see  FIG. 6 ) that are connected to juxtaposed fuse receiving sections  17   a  in a fuse casing  17 . 
     The fuse bus bars  23  include input side bus bars  25  and  26  and output side bus bars  27  and  28 . Ends of the bus bars  25  to  28  project into the respective fuse receiving sections  17   a  in an upper stage X and a lower stage Y in the fuse casing  17 . 
     In more detail,  FIG. 2  shows fuse bus bars  23  punched out from a sheet of a conductive metal plate and developed in a plane. The input side bus bars  25  and  26  on the upper stage X and the lower stage Y are provided with a plurality of press contact terminals  25   a  and  26   a  and a plurality of fuse side welding tabs  25   b  and  26   b . The terminals and tabs are made from a single metal plate. The first input side bus bars  26  are provided on the given positions with bridging portions a, b, and d to be cut off while some of the fuse side welding tabs  26   b  serve as tabs c and e to be cut off (hereinafter referred to “cut tab” or “cut tabs”). 
     The output side bus bars  27  and  28  are provided on the respective metal plate with press contact terminals  27   a  and  28   a , fuse side welding tabs  27   b  and  28   b.    
     The fuse bus bars  23  are shown in  FIG. 6  as typical bus bars  26  and  28  on the lower stage Y. The bus bars  26  and  28  are folded to a horizontal direction to form press contact terminals  26   a  and  28   a . A pair of terminals  30   a  and  30   b  of a fuse  30  to be inserted into the fuse receiving section  17   a  are forcibly fitted into the press contact terminals  26   a  and  28   a . The similar structure will be applied to the bus bars  25  and  27  on the upper stage X in the fuse casing  17 . 
     The fuse side welding tabs  25   b  to  28   b  are juxtaposed on a straight line and secured to one another by resistant welding so that the tabs  25   b  to  28   b  are opposed to the connector side welding tabs  20   a  of the bus bars  20  in the connector module  14 . 
     The fuse casing  17  is provided with juxtaposed multiple fuse receiving sections  17   a  to close the side opening  11   a . The fuse casing  17  is locked on the upper and lower casing members  11  and  18 . 
     The connector module  14  includes circuit boards that are stacked on one another in plural layers. Each of the circuit boards includes an insulation board  21  to which bus bars  20  for connectors are secured. The bus bars  20  are formed by punching out a sheet of a conductive metal plate into a circuit having a given configuration. Tabs project from the bus bars  20  on the circuit board (or through bus bars  22  in the relay module  15 ) and enter the connector receiving section  16   d  on the lower casing member  18 . 
     The connector module  14  opposed to the fuse module  16  is provided on a side with a plurality of connector side welding tabs  20   a  that are formed by folding ends of the bus bars  20  upward and downward in an L-shape and are disposed on a straight line. 
     The relay module  15  includes the bus bars  22  molded in the insulation board  13 . Relays (not shown) are mounted on a bottom surface of the insulation board  13 . Terminals of the relays are connected to the bus bars  22  by soldering. 
     An end of each bus bar  22  is folded upward and is connected to each bus bar  20  in the connector module  14 . The other end of each bus bar  22  projects downward from a side of the fuse module  16  and is opposed to each connector side welding tab  20   a  in the connector module  14  on a straight line to serve as a relay side welding tab  22   a.    
     The electronic control unit (ECU)  12  includes electronic parts mounted on a base plate. The insulation board  13  is disposed between the electronic control unit  12  and the connector module  14 . 
     Printed circuit conductors are juxtaposed on an end side of the base plate and are connected to vertical intermediate terminals (not shown) in an ECU connector  19 . A lower end of each intermediate terminal is connected to the tab  20   b  of each bus bar  20  in the connector module  14 . 
     The fuse module  16  is disposed in the junction box  10  so that the fuse side welding tabs  25   a  to  28   a  in the fuse module  16  are opposed to the connector side welding tabs  20   a  projecting from a side of the connector module  14 . The connector side welding tabs  20   a  juxtaposed on a straight line are superimposed on and welded to the fuse side welding tabs  25   a  to  28   a  successively. 
     The connector side welding tabs  20   a  and lower side welding tabs  27   a  and  28   a  are superimposed on the relay side welding tabs  22   a  in the relay module  15  and the connector side welding tabs  20   a  are interposed between the fuse side welding tabs  27   a  and  28   a  and the relay side welding tabs  22   a  to form a triple layer. The tabs in the triple layer are welded together. 
     The fuse casing  17  is put on the fuse module  16  disposed vertically on a side of the connector module  14 . The press contact terminals  25   a  to  28   a  in the fuse module  16  are inserted into the fuse receiving sections  17   a.    
     Under this condition, the upper and lower casing members  11  and  18  are interlocked together so that the upper and lower casing members  11  and  18  enclose the fuse casing  17 . 
       FIG. 3  shows a schematic diagram of a circuit to be altered by selectively cutting off the bridging portions a, b, and d of the fuse bus bars  23  in the fuse module  16  and the cut tabs c and e. Contact sections of relays are connected to the downstream of the fuse bus bars  23 .  FIG. 5  shows a table of selective cutting patterns of the bridging portions a, b, and d and cut tabs c and e. In  FIG. 5 , a round mark “O” designates a state in which the portions or tabs are not still cut off and a cross mark “X” designates a state in which the portions or tabs have been already cut off. 
     For instance, in the case of pattern A, the bridging portion a and the cut tab e are cut off while the bridging portions b and d and the cut tab c are retained or not cut off to form a circuit shown in FIG.  4 A. 
     Also, in the case of pattern B, the bridging portion b and the cut tab e are cut off while the bridging portions a and d and the cut tab c are not cut off to form a circuit shown in FIG.  4 B. In the case of pattern C, the cut tabs c and e are cut off while the bridging portions a, b, and d are not cut off to form a circuit shown in FIG.  4 C. In the case of pattern D, the bridging portions a and d are cut off while the bridging portion b and the cut tabs c and e are not cut off to form a circuit shown in FIG.  4 D. In the case of pattern E, the bridging portions b and d are cut off while the bridging portion a and the cut tabs c and e are not cut off to form a circuit shown in FIG.  4 E. In the case of pattern F, the bridging portion d and the cut tab c are cut off while the bridging portions a and b and the cut tab e are not cut off to form a circuit shown in FIG.  4 F. 
     The patterns A and D, in which the bridging portion a is cut off, will form a door circuit corresponding to a specification in which the ECU is disposed in only a driver&#39;s seat. The patterns B and E, in which the bridging portion b is cut off, will form a door circuit corresponding to a specification in which the ECU is disposed in each of driver&#39;s seat and passenger&#39;s seat. The patterns C and F, in which the cut tab c is cut off, will form a door circuit corresponding to a specification in which the ECU is disposed in each of four doors. 
     Also, the patterns A to C, in which the cut tab e is cut off, will form a roof circuit corresponding to a specification in which an output of a power source is disposed at an upstream from the relay. The patterns D to F, in which the bridging portion d is cut off, will form a roof circuit corresponding to a specification in which an output of a power source is disposed at a downstream from the relay. 
     Thus, it possible to form different circuits having patterns A to F by selectively cutting off the bridging portions a, b, and d, and/or the cut tabs c and e. It is possible to easily carry out an alteration of circuit design while maintaining a single kind of bus bars  23 . 
     Consequently, it is not necessary to produce new modules  14 ,  15 , and  16  together with a new junction box  10  upon alteration of circuit design. This will reduce kinds of parts and the load of controlling product numbers and lower cost in parts. 
     Also, the bus bars  20  in the connector module  14  are arranged in given circuit configurations and are stacked through the insulation board  13 . In the case where a plurality of bridging portions for selectively cutting the circuits are provided on the bus bars  20  in the connector module  14 , it is difficult to design all bus bars on the same layer adjacent to one another and it is necessary to increase the number of layers. This will increase cost. However, because the bridging portions a, b, and d and the cut tabs c and e are provided on the fuse bus bars  23  in the fuse module  16  in which input and output sections of circuits extend in parallel with each other, it is possible to easily set the bridging portions a, b, and d and the cut tabs c and e continuously. 
     Accordingly, even if a plurality of bridging portions a, b, and d for dividing the circuits are set in accordance with the specification of an automobile vehicle, the number of stacked layers of the insulation board  13  and bus bars  20  in the connector module  14  is not increased, an arrangement density of bus bars  20  can be enhanced, and an increase in cost and upsizing of a junction box  10  can be prevented. 
     The entire disclosure of Japanese Patent Application No. 2002-325472 filed on Nov. 8, 2002 including the specification, claims, drawings and summary is incorporated herein by reference in its entirety. 
     While the present invention has been particularly described, in conjunction with a specific preferred embodiment, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. It is therefore contemplated that the appended claim will embrace any such alternatives, modifications, and variations as falling within the true scope and spirit of the present invention.