Abstract:
An electrical connection box has a first casing part in which is mounted a bus bar laminate, and a second casing part in which a wiring substrate is accommodated. To achieve accurate alignment of projecting tabs of the bus bar laminate with connectors of the wiring substrate during connection of the casing parts, the first casing part has projections and the wiring substrate has recesses which mutually engage before the tabs enter the connectors. Direct alignment is achieved, increasing reliability of the product.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The invention relates to an electric connection box suitable to be mounted in, for example, a vehicle such as an automobile. 
     2. Description of Related Art 
     One form of an electric connection box provides a case composed of a casing part for a bus bar laminate and casing part for a wiring substrate. The bus bar laminate is formed by alternatingly laminating bus bars and insulation layers. A substrate connector making electrical connection with the bus bars is mounted on the wiring substrate. In assembly, the bus bars are received in the substrate casing part when the two casing parts are united, and the bus bars are connected with the substrate connector. It is required that the two casing parts are accurately positioned before combination so that the connection position of the bus bars coincides with the substrate connector. Accordingly, an electric connection box in which the two casing parts are joined when accurately positioned has been proposed. The electric connection box aligns the casing parts by bringing the wiring substrate casing part in contact with guide pieces formed on the upper face of the laminate casing part. However, in this box, bus bars are aligned with the substrate connector indirectly by positioning of the wiring substrate through its casing part. Therefore, there have been problems that deviation of the connection position of the bus bars with the connector occurs, and good connection cannot be achieved because of dimension tolerance of the respective casing parts, assembly error of the wiring substrate in its casing part, and the like. 
     U.S. Pat. No. 5,822,189 illustrates an electrical connection box, for automotive use, which also seeks to achieve good connection of a bus bar laminate and connectors of a wiring board. A lower casing contains a bus bar laminate having upwardly projecting tab terminals. Into this casing a circuit board is fitted, which carries on its edges connector housings which receive the tab terminals. In one embodiment, the connector housings are positioned by guide ribs of the lower casing, which also serve to ensure correct location of the connector housings on the circuit board. After fitting of the circuit board in this manner, an upper casing is fitted on the lower casing, pressing on the circuit board. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide an electric connection box capable of satisfactorily connecting a bus bar laminate with a connector. 
     According to the invention, there is provided an electrical connection box including a first casing part and a second casing part connectable with the first casing part. A bus bar laminate, having at least one bus bar and at least one insulation layer laminated together, is mounted in the first casing part and has projecting terminals. A wiring substrate is mounted in the second casing part and has connectors carried thereon, adapted to engage and make connection to the projecting terminals of the bus bar laminate when the casing parts are connected. The first casing part and the wiring substrate have portions constituting mutually engageable guides which, during connection of the casing parts, directly establish mutual alignment of the first casing part and the wiring substrate before the connectors engage the projecting terminals. 
     In the invention, when the first casing part with the bus bar laminate is combined with the second casing part with the wiring substrate, the wiring substrate is directly positioned against the laminate casing part by the positioning procedure performed by the guides. The positioning is carried out before the tab terminals of the bus bars are inserted in the connectors of the wiring substrate. Accordingly, it is assured that the connection position of the bus bars coincides with the connectors without being influenced by dimensional tolerance or the like of the first casing part. Therefore, good connection between the bus bars and the connectors can be achieved. 
     Preferably, the mutually engageable guides include at least one guide projection on one of the first casing part and the wiring substrate, and at least one guide recess in the other of the first casing part and the wiring substrate. The first casing part preferably has a substrate-receiving recess bounded by a surrounding wall which receives the wiring substrate when the casing parts are connected together, the guide projection is a protrusion on the surrounding wall projecting inwardly to said substrate-receiving recess, and the guide recess is a notch in a peripheral region of the wiring substrate. 
     To support and locate the terminals of the bus bar laminate, preferably the first casing part has a portion overlying the bus bar laminate and directly engaging the projecting terminals so as to determine the position of the projecting terminals relative to said first casing part. 
     Preferably, each of the first casing part and the wiring substrate has a pair of the portions constituting mutually engageable guides, located respectively at opposite sides of the electrical connection box. 
     Typically the wiring substrate is a planar board carrying wiring and a plurality of electrical components. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments of the invention will now be described by way of a non-limitative example, with reference to the accompanying drawings, in which: 
     FIG. 1 is an exploded perspective view of an electrical connection box embodying the invention; 
     FIG. 2 is a partial sectional view of the electrical connection box of FIG. 1; 
     FIGS. 3-7 are respective-partial sectional views of the box of FIG. 1 in successive stages during the joining of the two casing parts; and 
     FIG. 8 is a partial sectional view of the box when the joining of the casing parts is completed. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An electric connection box  11  for an automobile embodying the invention is shown in FIGS. 1-8. 
     As shown in FIGS. 1 and 2, the box  11 , typically arranged in the interior space of an automobile, has a first casing part for housing a bus bar laminate, here called a laminate case  12 , made by molding of a suitable synthetic resin, and a second casing part for housing a wiring substrate, here called a substrate case  13 , also made by molding of suitable synthetic resin and detachably mounted on the upper face of the laminate case  12 . The laminate case  12  is composed of a lower case part  16  and an upper case part  17  which are detachably joined. An upper opening of the lower case part  16  is occupied by the upper case part  17 . 
     In the laminate case  12 , a bus bar laminate  20  obtained by alternatingly laminating bus bars  18  made of a metal and insulation plates  19  made of a synthetic resin is accommodated. Bus terminals  18   a  formed on the bus bars  18  penetrate the upper case part  17  and protrude outward from the inside of the laminate case  12 . Structures  21  for receiving exterior connectors protrude at the lower face of the lower case part  16 . The laminate  20  is supported on the inside end faces of the respective structures  21 . 
     As the figures show, the upper case part  17  has upstanding sleeve-like projections  17   a  which directly engage and support the tab terminals  18   a.    
     From the bottom face of the lower case  16 , internally screw-threaded tubular fixing parts  22  penetrate upwardly through the laminate  20 . The upper end part of each fixing part  22  is inserted in a corresponding sleeve part  23  formed on the upper face of the upper case part  17 . Steps  22   a  on the exterior of the fixing parts  22  support the laminate  20 , in addition to the structures  21 . 
     As shown best in FIGS. 3-7, guide walls  24  stand up on the upper face of the upper case part  17 , and assist in positioning the substrate case  13 , when the laminate case  12  and substrate case  13  are joined. Hooking claws  24   a  are formed on the upper inside faces of the guide walls  24 . A recess  29  to receive a wiring substrate is defined on the upper face of the upper case part  17  by the approximately rectangular plan wall  25  inside the guide walls  24 . 
     Two guide projections  26   a  and  26   b  may be integrally formed (molded) with the wall  25  at opposite sides of the case  12  and project slightly higher than the upper end of the wall  25 . The projecting guide parts  26   a  and  26   b  oppose each other and are hollow inside to reduce the occurrence of mold sink on their surfaces in molding. 
     In the substrate case  13 , connector structures  28  (see FIG. 2) for a wire harness having terminals  27  inside are integrally formed on the upper part of the case. The wiring substrate  30  is a planar board having electrical wiring on its surface and carrying electrical components. The wiring substrate  30  installed and fixed by screws  33  on the substrate case  13 , and nearly completely closes the lower opening  13   a  (see FIG.  3 ). Through apertures  35  (see FIG. 2) in the substrate  30 , screws  34  are inserted into the fixing parts  22  of the laminate case  12  fixing the laminate case  12  and the substrate  13  together. Hooking projections  13   b  are formed at places corresponding to the hooking claws  24 a, on the outside face of the substrate case  13 . 
     To make connection with the bus bars, connectors  31  are carried on the wiring substrate  30 . For example, one of the connectors  31  is shown in FIGS. 2-8. Connecting terminals  36  connected to the wiring substrate  30  are provided in the connector  31 . The tab terminals  18   a  make connection with the connecting terminals  36  through holes  30   a  in the wiring substrate  30 , when the cases  12  and  13  are joined. 
     As shown in FIGS. 1 and 3, two notches  37   a  and  37   b  acting as guide recesses are formed on opposite ends of the wiring substrate  30 , to cooperate with the guide projections  26   a  and  26   b.  When the cases  12  and  13  are joined, there is only slight clearance between the guide projections  26   a  and  26   b  and the notches  37   a  and  37   b,  respectively. 
     Further, the engagement of the guide projections  26   a  and  26   b  and the notches  37   a  and  37   b  is designed to take place before the engagement of the tab terminals  18   a  with the connecting terminals  36 , when the cases  12  and  13  are combined. More specifically, the engagement of the guides  37   a  and  37   b  and  26   a  and  26   b  occurs before the tab terminal  18   a  is inserted in the insertion hole  30   a  and the connector  31 . For this purpose, the guide projections  26   a  and  26   b  stand higher than the tab terminals  18   a,  in the direction of mutual approach of the cases  12  and  13  during connection. 
     The assembly of the electrical connection box  11  is as follows: 
     As shown in FIG. 3, the recess  2   a  of the upper case part  17  is confronted with the lower opening  13   a  of the substrate case  13 . As shown in FIG. 4, the laminate case  12  is approached to the substrate case  13 . Then, as shown in FIG. 5, a rim part of the substrate case  13  is brought in contact with the inside face of the guide walls  24 , and the positions of the respective notches  37   a  and  37   b  formed on the wiring substrate  30  are matched with the respective positions of the guide projections  26   a  and  26   b  provided at the edge of the recess  29 . As shown in FIG. 6, subsequently, the respective notches  37   a  and  37   b  engage with the respective guide projections  26   a  and  26   b.  The wiring substrate  30  is thus directly aligned to the laminate case  12 . The correct position of the tab terminals  18   a  of the bus bars  18  with respect to the connecting terminals  36  of the connector  31  is achieved. As the figures show, the substrate  30  and the case  12  are aligned before the tab terminals  18   a  enter the apertures  30   a.    
     Then, as shown in FIG. 7, the wiring substrate  30  is received in the recess  29  while the notches  37   a  and  37   b  slide along the two guide projections  26   a  and  26   b.  Further, as shown in FIG. 8, the tab terminals  18   a  of the bus bars  18  are inserted in the connectors  31  through the insertion holes  30   a.  At the same time, the hooking claws  24   a  provided on the guide walls  24  are hooked on the hooking projections  13   b  of the case  13 , to lock the cases  12  and  13  together. Then, as shown in FIGS. 1 and 2, the screws  34  are passed through holes  35 , and engaged with the threaded parts  27 . 
     The following advantages can be obtained with this embodiment. 
     (1) The wiring substrate  30  is aligned relative to the laminate case  12  before the tab terminals  18   a  formed on the bus bars  18  are inserted in the connectors  31 , by directly positioning the wiring substrate  30  against the laminate case  12 . Accordingly, the correct connection position of the bus terminals  18   a  with respect to the connecting terminal  36  can be achieved without being influenced by dimension tolerance of the laminate case or the substrate case, installation aberration of the wiring substrate  30  or the like. Therefore, a good connection between the bus bars  18  and the connector  31  can be achieved, and the reliability of the electric connection box  11  can be improved. 
     (2) The guide projections  26   a  and  26   b  are formed on the wall  25  provided on the laminate case  12 . The notches  37   a  and  37   b  are formed on the wiring substrate  30 . With these parts having a concave and convex relationship, the positioning of the wiring substrate  30  with respect to the case  12  can be easily carried out. 
     (3) The notches  37   a  and  37   b  are formed on the rim of the wiring substrate  30 , so that restrictions on electric circuits can be made less in comparison with a case of forming aligning parts at a central part of the wiring substrate  30 , and the degree of freedom of design can be enhanced. 
     (4) The guide projections  26   a  and  26   b  are integrally formed on the inside face of the wall  25  bounding the recess  29 , so that the strength of the wall  25  can be improved. As the guide projections  26   a  and  26   b  are hollow, surface sink marks can be avoided. Therefore, the molding accuracy of the guide projections  26   a  and  26   b  is enhanced. 
     (5) As the guide projections  26   a  and  26   b  and the notches  37   a  and  37   b  are both provided in plural numbers, and are opposed to each other at opposite sides of the cases  12  and  13 , the positioning accuracy of the wiring substrate  30  against the case  12  can be more enhanced. 
     Modified embodiments are described below: 
     The respective numbers of the guide projections  26   a  and  26   b  and the notches  37   a  and  37   b  were described as two, but may be changed to one, three or more. 
     In the above embodiment, the guide projections  26   a  and  26   b  were provided on the case  12 , and the notches  37   a  and  37   b  on the wiring substrate  30 . This relation may be inverted. Namely, the notches may be on the case  12 , and the guide projections may be on the wiring substrate  30 . 
     In the above embodiment, the positioning of the wiring substrate  30  with respect to the case  12  was carried out by concave and convex parts. Alternatively, this positioning may be achieved by holes in the wiring substrate  30 , and protrusions on the bottom face of the recess  29  engaging these holes. 
     While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.