Abstract:
To prevent an incorporated bus bar laminate from being subjected to an excessive pressure when a case is locked, lock fitting is carried out by interfitting an upper case and a lower case in an electric junction box which incorporates a bus bar laminate between holding faces provided on the upper case and the lower case opposite to each other. Seatings protrude in opposite direction from the inside of either or both cases, setting a protruded dimension from the holding surface of the seating to be slightly larger than a thickness of the bus bar laminate and almost equal to a dimension between the holding surfaces. The seating contacts an opposite holding surface, and the case is thus not forced to move in a pressing direction against the bus bar laminate.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electric junction box, and, more specifically, to an electric junction box that prevents generation of deformation or damages of a bus bar laminate incorporated in a case when the case is pressed down for lock connection. 
     2. Description of the Related Art 
     An electric junction box is used for branch connection of an automobile wire harness with various electrical equipment. For instance, a joint box J/B, as shown in FIGS. 9 and 10, connects and locks a connecting hole 2a with an external surrounding wall of an upper case 2 onto a connecting claw 1a of the external surrounding wall of a lower case 1 by covering the upper case 2 onto the lower case 1. 
     Inside the lower case 1 and the upper case 2, a bus bar laminate 3 (which includes a bus bar laminated to an isolated board) is held between a holding surface 2b of the upper case 2 and a holding surface 1b of the lower case 1. The distance T between the holding surfaces 1b and 2b is set to a thickness t1 of the bus bar laminate 3. 
     However, when connecting and locking a connecting hole 2a of the upper case 2 with a connecting claw 1a on the lower case 1, and when inserting the upper case 2 in a covering direction due to connecting claw 1a and connecting hole 1a being locked, because a length h2 is larger than the height h1 of the connecting claw 1a, a useless load may be added to the bus bar laminate 3 which is directly pressed down by the holding surface 2b on the upper case 2 with a length wider than the length h2 of connecting hole 2a. In such a case, since there may be deformation of the bus bar (bending of the circuit, buckling of the terminal, etc.) and damages of the base material, etc., problems occurred that degraded the quality with a proportional increase of defective units during production and assembling. 
     SUMMARY OF THE INVENTION 
     The present invention was made to solve the above-mentioned problem, and one purpose of the present invention is to provide an electric junction box that prevents generation of deformation or damages of the incorporated bus bar laminate. 
     According to one aspect of the present invention, there is provided an electric junction box which incorporates a bus bar laminate between opposed holding surfaces provided on an upper case and a lower case by interfitting the upper case and lower case and performing lock fitting. A seating protrudes from at least one inner surface of at least one of the cases. A protruded dimension from a holding surface of each seating is set slightly larger than the thickness of bus bar laminate and is also set to almost an equal dimension between the opposed holding surfaces, and the case is restricted so that it does not move in a direction to press on the bus bar laminate by making the seating connect with the opposite holding surface. 
     At least one of the upper and lower cases, for instance, when covering the lower case on the upper case and the upper case is pressed down on the lower case for locking a connecting claw and a connecting hole, is provided with a seating protruding from the inside surface of upper case to restrict the insertion of the upper case by contacting the holding surface of the lower case. Because the seating protrudes slightly more than a thickness of the bus bar laminate from the holding surface on the upper case, a dimension between the holding surfaces of the upper case and the lower case will not become less than the bus bar laminate. Therefore, the bus bar laminate will not be pressed down and/or deformed by the pressing of the upper case. 
     It is preferable to provide the seating near the connecting claw and the connecting hole. In such a way, if the seating is provided near the locked area, a force is primarily given to an area near the lock of the case when lock fixing, but excessive pressing can surely be prevented by the seating. 
     It is preferable to provide a seating at least on four corners of the case. In such a way, providing seating on four corners of the case can prevent excessive pressing when carrying out forceful insertion on four corners of the case. 
     The seating can be commonly used together with a rib for preventing deflected opening of the external surrounding wall on the other case. With this structure, it is not necessary to provide an additional seating. 
     According to another aspect of the present invention, there is provided an electric junction box comprising a lower case having a lower holding surface, an upper case attachable to the lower case using a predetermined force, the said upper case having an upper holding surface, a bus bar laminate positioned between the upper holding surface and the lower holding surface, and structure for maintaining a predetermined distance no less than a thickness of the bus bar laminate between the upper holding surface and the lower holding surface despite application of the predetermined force. 
     According to still another aspect of the present invention, there is provided a method for assembling a junction box incorporating a bus bar laminate. The method comprises inserting a bus bar laminate between an upper case and a lower case of the junction box, pressing the upper and lower cases together using a predetermined force to sandwich the bus bar laminate, maintaining a predetermined distance between an upper surface of the upper case and a lower surface of the lower case that is no less than a thickness of the bus bar laminate. 
    
    
     These and other salient features of the invention will become apparent from or described with reference to the following detailed description of preferred embodiments. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described in detail with reference to the following drawings in which: 
     FIG. 1 shows a bottom view of the upper case of the electric junction box of the present invention; 
     FIG. 2(A) shows a bottom view on the lower case of the electric junction box of the present invention, and FIG. 2(B) shows a side view thereof; 
     FIG. 3 shows a sectional view III--III in FIG. 1; 
     FIG. 4 shows a sectional view of a position similar to FIG. 3 when the upper case and the lower case are fixedly locked; 
     FIG. 5(A) shows a bottom view illustrating a rib for preventing deflected opening in an upper case side, and FIG. 5(B) shows a sectional view V--V of FIG. 5(A); 
     FIG. 6 shows a bottom view of a condition of the protrusion interfitting the lower case onto the rib for preventing the deflected opening; 
     FIG. 7 shows a sectional view VII--VII of FIG. 6; 
     FIG. 8 shows a sectional view VIII--VIII of FIG. 7; 
     FIG. 9 shows a partial sectional view of a conventional electric junction box; and 
     FIG. 10 shows a schematic view of a bus bar housing area of the conventional electric junction box. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     As shown in FIGS. 2(A) and 2(B), a lower case of an electric junction box J/B includes, for example, eight connecting claws 5a-5h. Two sets of clawsare installed along each side surface of an external surrounding wall 50 ofthe lower case 5 of the electric junction box J/B. As shown in FIG. 1, a total of eight connecting holes 6a-6h are provided on an external surrounding wall 60 of an upper case 6 to correspond with respective connecting claws 5a-5h of the lower case 5. With the lower case 5 and upper case 6 as shown in FIG. 4, the upper case 6 covers the lower case 5,which connects the connecting hole 6a on the upper case 6 with the connecting claw 5a on lower case 5. In the same manner, claw 5b is connected with hole 6b, claw 5c with hole 6c, etc., each of which is connected and then locked. 
     Furthermore, as shown in FIG. 2, for example, a total of five T-shaped protrusions 5p-5t for preventing deflected opening are provided on each surface and corner of the exterior surrounding wall 50 on the lower case 5. In addition, as shown in FIG. 1, a total of five T-shaped ribs 6p-6t for preventing deflected opening are provided on the external surrounding wall 60 on the upper case 6 in registry with each protrusion 5p-5t on the lower case 5. The protrusions 5p-5t for preventing deflected opening and ribs 6p-6t for preventing deflected opening are designed to prevent the deflected opening of the external surrounding wall 60 of the upper case 6 by covering a rib 6p on the upper case 6 onto a protrusion 5p on the lowercase 5 when covering the upper case 6 over the protrusion 5p of lower case 5, with the same manner for rib/protrusion combinations 5q-6q, 5r-6r, etc.as shown in FIGS. 6-8. 
     As shown in FIG. 2(B), the entire upper surface on the lower case 5 becomesa flat holding area 5j that holds a lower surface 3a of bus bar laminate 3.Also, as shown in FIG. 1, the lower end surface of a frame provided properly on the inside of upper case 6 becomes a holding surface 6j that holds an upper surface 3b of the bus bar laminate 3. Each of these holdingsurfaces 5j and 6j is so designed that a slight clearance (for example, about 0.5 mm) for a thickness t1 of bus bar clearance 3 becomes a holding distance T1 to avoid a gap which bears movement in a covering direction (i.e. up and down directions). The bus bar laminate 3 is incorporated in the inside of both cases 5 and 6 when the connecting holes 6a-6h are connected on the connecting claws 5a-5h and locked with the upper case 6 covered on the lower case 5. 
     As shown in FIG. 3, on two corners on a lower side of the inside of the upper case 6, a first seating 6k is provided that connects a holding surface 5j of the lower case 5 when both cases 5 and 6 are covered and locked as shown in FIGS. 3 and 4. The first seating 6k sets a height T2 from the holding surface 6j with the same distance as T1 between the holding surfaces 5j and 6j (or slightly shorter), and also sets a height slightly larger than a thickness t1 of the bus bar laminate 3 (T1≧T2&gt;t1). 
     Likewise, a second seating 6m for connecting the holding surface 5j on the lower case 5 is provided to use together with each of the ribs 6p-6t when covering and locking both cases 5 and 6 as shown in FIGS. 5(A), 5(B), and 6-8. With regard to the second seating 6m, in the same manner as the firstseating 6k, a height T2 from the holding surface 6j is set with a distance equal to a distance T1 (or slightly shorter, and slightly larger than a thickness t1 (T1≧T2&gt;t1). 
     As mentioned above, with a structure provided with the first seating 6k andthe second seating 6m, when pressing the upper case 6 in a covering direction for locking the connecting claws 5a-5h and connecting holes 6a-6h by covering the upper case 6 onto the lower case 5, each first seating 6k and second seating 6m connect with the holding area 5j of lowercase 5 when both case 5 and 6 are locked. Therefore, the upper case 6 will not move in a covering direction, or to a direction of a lower case side by more than a thickness t1 of the bus bar laminate 3. Therefore, possibledeformation of bus bar or damage of base material will not occur, because unnecessary load will not be applied owing to direct pressing of the holding surface 6j on the upper case 6 to the bus bar laminate 3. 
     In the above-mentioned embodiment, since the first and the second seatings 6k and 6m are provided around the vicinity of respective connecting claws 5a-5h and connecting holes 6a-6h, there is no possibility of needless loadto the bus bar laminate 3 owing to distortion, etc. of the holding surface 6j on the upper case 6 because respective seatings 6k and 6m will contact the holding surface 5j on the lower case 5 at a position where the greatest force is given when covering the upper case 6 in a covering direction. 
     Furthermore, because the seatings 6k and 6m are provided on four corners ofupper case 6, pressing with the upper case upon the bus bar laminate 3 can be avoided when covering in a covering direction by giving pressure onto 4corners of the upper case 6. In addition, because the second seating 6m is used together with ribs 6p-6t for preventing deflected opening of the external surrounding wall 60 on the upper case, it is compact. 
     With the above-mentioned embodiment, the lower case 5 is covered and interfitted with the upper case 6, but covering the upper case 6 with the lower case 5 and then interfitting is also preferred. In such a case, the connecting claws are provided on the upper case 6 while the connecting holes are provided on the lower case 5. 
     In addition, although respective seatings 6k and 6m are provided by protruding downward from the inner face of the upper case 6, providing them by protruding upward from the inner face of the lower case 5 is also preferred. That is, it is also acceptable to protrude the seatings upwardswith a dimension a little larger than the thickness of bus bar laminate from the holding surface of lower case, thus making contact with the holding face of the upper case. 
     As is apparent from the description above, with the electric junction box of the present invention, when inserting one case for locking in a covering direction with another case, because the seating contacts a holding face of opposite case, moving the case becomes difficult for the insertion up to a distance larger than the thickness of bus bar laminate. Therefore, no unwanted load is applied to the bus bar laminate by pushing the case, thereby surely preventing the generation of deformation of the bus bar and damages of base material. As a consequence, a proportion of defective units during production and assembling is reduced, thereby improving quality. 
     As described, if a seating is provided in the vicinity of connecting claws and connecting holes, when pushing one case in a covering direction, because the seating will contact a holding face on the opposite case at a position where a force is primarily directed, pressing the case in a covering side is avoided, which prevents the application of an unnecessaryload to the bus bar laminate. 
     As described, if the seating is provided at least on four corners when forces are applied to four corners of either case for inserting in a covering direction, pressing the bus bar with the case at an insertion area can be avoided in advance. 
     As described, when the seating is used together with a rib for preventing deflected opening of the external surrounding wall on either case, no special space is required for seating, which is advantageous for space saving. 
     The invention has been described in detail with reference to preferred embodiments thereof, which are intended to be illustrative, not limiting. Various modifications and changes can be made without departing from the spirit and scope of the invention as defined in the appended claims.