Abstract:
A terminal through-hole in which a given clearance exists between an inner surface of a terminal through-hole in an insulation plate and a whole peripheral surface of a terminal. The terminal through-hole includes protrusions for correction of alignment. The terminal includes bulged portions that engage the protrusions in the terminal through-hole when an end of the terminal is inserted into a terminal hole in a printed board. Before soldering the end of the terminal to a conductor on the printed board, the insulation plate is moved toward the other end of the terminal and the bulged portions of the terminal no longer engage the protrusions in the terminal through-hole. By thus releasing correction of alignment of the terminal after insertion, the possibility of cracks in the soldered part is reduced.

Description:
This invention relates to a terminal connection structure, an electrical junction box having the terminal connection structure, and a method for assembling the electrical junction box. In more detail, in the case where a terminal is soldered on a conductor on a printed board, alignment of the terminal is corrected to enable the terminal to be readily inserted into a terminal hole in the printed board. This application claims priority from Japanese Patent Application Number JP-2005-211446 filed Jul. 21, 2005, the entire contents of which are incorporated herein by reference. 
   BACKGROUND 
   Conventionally, an electrical junction box to be mounted on a motor vehicle includes a casing, a laminated body that layers bus bars and insulation plates alternately, and a printed board. The laminated body and printed board are contained in the casing. A terminal is soldered on a conductor on the printed board. 
   As an example of such an electrical junction box, the present applicant has provided an electrical junction box  1  shown in  FIG. 6  and disclosed in Japanese Patent Public Disclosure 2003-249288 (JP-A-2003-249288). In the electrical junction box  1 , in order to interconnect a terminal  2   a  of a bus bar  2  and a conductor on a printed board  3 , as shown in  FIG. 7 , a partition insulation plate  5  is placed between the printed board  3  and a laminated body  4  in which the bus bars  2  and insulation plates are superposed alternately. The partition insulation plate  5  has a tab correction tube  5   a  that projects upward to correct alignment of the terminal  2   a.    
   In a connection method using the partition insulation plate  5 , firstly, the printed board  3  is placed on a top surface of the tab correction tube  5   a  so that a tab correction hole  5   b  in the tab correction tube  5   a  is communicated with a terminal hole  3   a  in the printed board  3 . Then, as the partition insulation plate  5  and printed board  3  are moved down toward the bus bars  2 , the terminal  2   a  is inserted into the tab correction hole  5   b  in the tab correction tube  5   a  to correct alignment of the terminal  2   a . The terminal  2   a , the alignment of which is corrected, is inserted into the terminal hole  3   a  in the printed board  3  and the terminal  2   a  is soldered on the conductor on the printed board  3  at a position H. 
   The printed board  3 , after it is moved down toward the bus bars  2 , is supported at a given height by tubular base  6  that projects from the insulation plate in the laminated body  4 . The printed board  3  is secured to the tubular base  6  by a screw N. 
   In the above connection method, since the alignment of the terminal  2   a  to be inserted into the terminal hole  3   a  in the printed board  3  is corrected by the tab correction tube  5   a  on the partition insulation plate  5   a , it is possible to easily insert the terminal  2   a  into the terminal hole  3   a  and to readily complete interconnecting the terminal  2   a  and the conductor on the printed board  3 . 
   SUMMARY 
   However, in the above connection method, even after soldering the terminal  2   a  of the bus bar  2  on the conductor on the printed board  3 , the tab correction tube  5   a  continues to maintain the alignment of the terminal  2   a . Thus, in the case where the terminal  2   a  is maintained in correct alignment after connection to the printed board  3 , the terminal hole  3   a  in the printed board  3  may shift position relative to the position of the terminal  2   a , which has been positioned by the insulation plate. This shift can apply a load to the soldered part H, causing cracks in the soldered part H, and thereby generating a possible contact failure. This relative position shift may be caused, for example, by changes in temperature, since the printed board and the resin insulation plate have different heat expansion characteristics. 
   In view of the above problems, an object of exemplary embodiments of the present invention is to correct alignment of a terminal during insertion of the terminal in a printed board so that the terminal can be easily inserted into the terminal hole in the printed board, and to reduce the risk of cracks in a soldered part by releasing correction of alignment of the terminal after insertion. 
   In order to address the above problems, exemplary embodiments of the present invention provide a terminal connection structure with a printed board having a terminal hole and a conductor and an insulation plate having a terminal through-hole. A terminal may be inserted, in an insertion direction, via the terminal through-hole in the insulation plate into the terminal hole which provides a given clearance between an inner surface of the terminal through-hole and a whole peripheral surface of the terminal. The terminal through-hole has, on opposing portions of the inner surface, protrusions for correction of alignment of the terminal. The terminal is provided with bulged portions that protrude from the terminal in a direction perpendicular to the direction of insertion and are sized and positioned to be capable of engagement with the protrusions for correction of alignment of the terminal. In the final assembled state of the terminal connection structure, the bulged portions of the terminal do not engage the protrusions for correction of alignment, so that a given clearance exists between the inner surface of the terminal through-hole and the whole peripheral surface of the tabl-like terminal, and one end of the terminal is soldered to the conductor. 
   According to the above connection structure, when the terminal is inserted into the terminal hole in the printed board, the bulged portions of the terminal are located at the same height as the protrusions for correction of alignment in the terminal through-hole in the vertical direction (or the direction of insertion) such that the bulged portions of the terminal are positioned and held by the protrusions for correction of alignment. Accordingly, it is possible to readily insert the terminal into the terminal hole in the printed board and to enhance efficiency in working. 
   After inserting the terminal into the terminal hole in the printed board, the bulged portions of the terminal are shifted relative to the protrusions in the terminal through-hole by movement of the insulation plate away from the printed board. The terminal is released from correction of alignment that is caused by the protrusions in the terminal through-hole and the bulged portions of terminal. Consequently, even if the terminal through-holes in the insulation plates are shifted perpendicularly from the direction of insertion of the terminal relative to the terminal hole in the printed board due to differential heat expansion between the printed board and insulation plate or other reasons, the terminal can also move with shifts of the printed board without interference from the protrusions on the terminal through-hole. Accordingly, the risk of a large load being applied to the soldered part that interconnects the terminal and the conductor on the printed board, and cracks occurring in the soldered part, may be reduced. 
   In more detail, the terminal through-hole in the insulation plate may be provided on a peripheral edge at a terminal insertion side with a tapered guide portion and on a peripheral edge at the opposite side with a projecting peripheral wall to form a terminal insertion frame. Protrusions for correction of alignment are provided on an inner surface of the terminal through-hole at a terminal insertion side of the terminal insertion frame. The bulged portions of the terminal are disposed in the terminal insertion frame to be shifted away, in a direction parallel to the direction of insertion, from the protrusions on the inner surface of the terminal through-hole, before the terminal is soldered on the printed plate. 
   The protrusions for correction of alignment may be formed into L-shaped configurations, each of which extends along a corner of the inner surface of the terminal through-hole. 
   According to the above construction, a pair of the L-shaped protrusions for correction of alignment can engage and position the terminal in every direction. Also, since the protrusions are provided only on the diagonal corners in the terminal through-hole, and not on the whole periphery of the inner surface of the terminal through-hole, it should be possible to smoothly insert the terminal into the space between the protrusions in the terminal through-hole. 
   In the condition where alignment of the terminal is corrected by the protrusions for correction of alignment in the terminal through-hole in the insulation plate and by the bulged portions of the terminal, at least a part of the outer surfaces of the bulged portions of the terminal may contact with at least a part of the inner surfaces of the protrusions for correction of alignment. 
   According to the above construction, it is possible to reliably correct the alignment of the terminal and to readily insert the terminal into the terminal hole in the printed board by contacting at least a part of the bulged portions of the terminal with at least a part of the protrusions in the terminal through-hole. In this case, since the terminal is released from correction of alignment after inserting the terminal into the terminal hole in the printed board, subsequent problems of crack formation in the soldered part may be reduced. 
   Exemplary embodiments of the present invention are directed to an electrical junction box having the terminal connection structure described above. The insulation plate may be part of a laminated body that superposes bus bars and insulation plates alternately, and the laminated body and the printed board may be contained in a casing assembly of the electrical junction box. The terminal projects from the bus bar. The terminal is soldered on a conductor on the printed board. The protrusions for correction of alignment are provided on the terminal through-hole in the outermost insulation plate at a printed board arrangement side. 
   Furthermore, exemplary embodiments of the present invention are directed to a method for assembling an electrical junction box. The method may include the following steps. A first step space the printed board and the insulation plate from another insulation plate, using a positioning jig, such that the bulged portions of the terminal engage the protrusions for correction of alignment. Next, the positioning jig is withdrawn until the insulation plate is supported by the other insulation plate, and the bulged portions of the terminal no longer engage the protrusions for correction of alignment. Finally, the terminal is soldered to the conductor. 
   According to the method for assembling the above electrical junction box, when the terminal of the bus bar is inserted into the terminal hole in the printed board, the positioning jig supports the outermost insulation plate at a given position in height spaced away from other insulation plates and the bulged portions of the terminal are aligned with the protrusions in the terminal through-hole. Accordingly, the alignment of the terminal of the bus bar is corrected by the protrusions for correction of alignment and bulged portions of the terminal, and the terminal of the bus bar can be readily inserted into the terminal hole in the printed board, thereby enhancing efficiency of the assembly operation. 
   After inserting the terminal into the terminal hole in the printed board, the positioning jig is extracted from the jig through-hole, and the outermost insulation plate is moved toward the other insulation plates, and may be placed on the other insulation plates. The movement of the outermost insulation plate causes the bulged portions of the terminal to shift relative to the protrusions in the terminal through-hole with respect to the direction of movement of the outermost insulation plate. Consequently, the terminal is released from correction of alignment by the protrusions and bulged portions. Accordingly, even if the terminal through-hole in the outermost insulation plate subsequently shifts relative to the terminal hole in the printed board due to, for example, heat expansion, the end of the terminal soldered to the printed board should be able to move with the movement of the printed board without interference from the protrusions for correction of alignment in the terminal through-hole in the outermost insulation plate. This can reduce the risk of a large load being applied to the soldered part which interconnects the terminal and the conductor on the printed board, thereby reducing the possibility of cracks in the soldered part. 
   As described above, according to the exemplary embodiments of the present invention, when the terminal is inserted into the terminal hole in the printed board, the bulged portions of the terminal are aligned with the protrusions for correction of alignment in the terminal through-hole and the alignment of the terminal is corrected by the protrusions for correction of alignment and the bulged portions of the terminal. Accordingly, it is possible to readily insert the terminal into the terminal hole in the printed board, thereby enhancing efficiency of an assembly operation. 
   After inserting the terminal into the terminal hole in the printed board, the position of the bulged portions of the terminal is shifted relative to the protrusions in the terminal through-hole insertion direction by movement of the outermost insulation plate, so that the terminal is released from correction of alignment by the protrusions in the terminal through-hole and the bulged portions of the terminal. Consequently, even if the terminal through-hole in the insulation plate is shifted particularly to the insertion direction relative to the terminal hole in the printed board due to heat expansion or some other cause, the end-of-tab terminal soldered to the printed board should be able to move with the movement of the printed board without interference with the protrusions in the terminal through-hole in the insulation plate. Accordingly, the risk of a large load being applied to the soldered part that interconnects the terminal and the conductor on the printed board, and the possibility of cracks in the soldered part, may be reduced. 
   According to the above-described method for assembling the electrical junction box, when the terminal of the bus bar is inserted into the terminal hole in the printed board, the positioning jig supports the outermost insulation plate at a given position spaced away from the other insulation plates and the bulged portions of the terminal are aligned with and engage the protrusions in the terminal through-hole with respect to the insertion direction. Accordingly, the alignment of the terminal of the bus bar is corrected by the bulged portions of the terminal and the protrusions for correction of alignment in the terminal through-hole, and the terminal of the bus bar can be readily inserted into the terminal hole in the printed board, thereby enhancing efficiency of the assembly operation. 
   After inserting the terminal into the terminal hole in the printed board, the positioning jig is extracted from the jig through-hole, and the outermost insulation plate is moved toward the other insulation plates. This causes the bulged portions of the terminal to shift relative to the protrusions in the terminal through-hole with respect to the insertion direction. Consequently, the terminal can be released from correction of alignment by the combination of the protrusions and bulged portions. 
   These and other objects, advantages and features are described in or apparent from the following detailed description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the present invention will be described below, with reference to the drawings, in which like numbers represent like parts, and in which: 
       FIG. 1  is a sectional view of an electrical junction box of an embodiment in accordance with the present invention; 
       FIG. 2  is an enlarged sectional view of main parts of a laminated body and a first printed board; 
       FIG. 3  is a plan view of a terminal inserted into a terminal through-hole in an insulation plate; 
       FIGS. 4A to 4C  are explanatory views of a method for interconnecting a terminal provided on a bus bar in a laminated body and a conductor on a first printed board; 
       FIG. 5  shows another embodiment of the present invention; 
       FIG. 6  is a sectional view of a conventional electrical junction box; and 
       FIG. 7  shows a method for assembling the conventional electrical junction box. 
   

   DETAILED DESCRIPTION OF EMBODIMENTS 
     FIGS. 1 through 4  show an embodiment of the present invention. An electrical junction box  10  includes a casing assembly including an upper casing  11 , an intermediate casing  12 , and a lower casing  13 . A laminated body  20 , a first printed board  40 , a second printed board  50 , and a third printed board  60  are spaced away from one another vertically and secured in the casing assembly. The laminated body  20  is formed by alternately layering bus bars  21  made of a conductive metal plate and insulation plates  30  made of a resin material. The bus bars  21  and conductors on the three printed boards  40 ,  50 ,  60  are connected to given terminals through a relay connector  70  mounted on the second printed board  50  or a relay connector  80  on the third printed board  60 . 
   As shown in  FIG. 2 , the laminated body  20  and first printed board  40  are disposed in the casing assembly so that the laminated body  20  is placed on a top surface of the first printed board  40 . In the present embodiment, the laminated body  20  includes four insulation plates  30 , although this invention may be applied to any number of insulation plates. The outermost insulation plate  30 A (lowermost layer in  FIG. 2 ) is disposed above the first printed board  40  while the other insulation plates  30 B,  30 C, and  30 D are disposed above the outermost insulation plate  30 A. 
   A given insulation plate out of the insulation plates  30 A to  30 D is provided with a terminal through-hole  31  into which a terminal  22  on the bus bar  21  is inserted. The terminal  22  may have a rectangular cross section. 
   The terminal through-hole  31  in the outermost insulation plate  30 A has a rectangular cross section, and the walls of the terminal through-hole are spaced away from the entire periphery of the terminal  22  by a given clearance. The terminal through-hole  31  is provided on a peripheral edge at a terminal insertion side (an upper side in  FIG. 2 , although any orientation is possible) with a tapered guide portion  34  and on a peripheral edge at an opposite side (a lower side in  FIG. 2 , although any orientation is possible) with a projecting peripheral wall to form a terminal insertion frame  35 . A pair of protrusions  32  for correction of alignment (hereinafter referred to “protrusions”  32 ) is provided on diagonal corners on an inner surface  31   a  of the terminal through-hole  31 . As shown in  FIG. 3 , each protrusion  32  may have an L-shaped configuration when viewed through the terminal through-hole and extends along the corner of the inner surface  31   a  of the terminal through-hole  31 . Also, the protrusions  32  are provided at a terminal insertion side (at a side of the guide portion  34 ) of the terminal insertion frame  35  to extend an inner surface  32   a  of each protrusion  32  to each guide portion  34 . 
   The terminal  22  on the bus bar  21  is provided on the opposite sides of an intermediate position with bulged portions  23 . The bulged portions  23  are located at a position lower than the protrusions  32  in the terminal through-hole  31 . The bulged portions  23  are provided with tapered surfaces (lower surfaces in the present embodiment) at a tab distal end side. Also, a distal end of the terminal  22  projects from a lower end of the terminal through-hole  31 , passes a terminal hole  41  in the first printed board  40 , and is soldered on a conductor  42  at a position H. 
   As shown in  FIG. 3 , the inner surfaces  32   a  of the protrusions  32  are disposed near the outer surfaces  23   a  of the bulged portions  23  of the terminal  22  at a position closer than the inner surface  31   a  of the terminal through-hole  31 . 
   As mentioned above, the bulged portions  23  of the terminal  22  are shifted from the protrusions  32  in the terminal through-hole  31  in the direction of terminal insertion. However, when the terminal  22  is inserted into a terminal hole  41  in the first printed board  40 , the bulged portions  23  are aligned with the protrusions  32  in the direction of terminal insertion, and the protrusions  32  clamp and hold the bulged portions  23  in position. 
   The insulation plates  30 A to  30 D are provided together with jig through-holes  33  through which a positioning jig  90  (described below) passes. The jig through-holes  33  have a same large diameter portion  33   a  extending from the upper insulation plate  30 D to a point part-way through the outermost insulation plate  30 A, and have a small diameter portion  33   b  at the lower end of the outermost insulation plate  30 A. A peripheral wall projects around the jig through-hole  33  in the outermost insulation plate  30 A at the side of the first printed board  40  to form a jig insertion frame  36 . A distal end of the jig insertion frame  36  contacts a top surface of the first printed board  40 . Jig through-holes  43  are provided in the first printed plate  40 . The jig through-holes  43  is communicate with the jig through-holes  33  in the insulation plates  30 A to  30 D and have substantially the same diameter as that of the small diameter portions  33   b  in the jig through-holes  33 . In the present embodiment, the terminal through-holes  31  are between the jig through-holes  33  while terminal hole  41  in the first printed board  40  is between the jig through-holes  43 . 
   One or more positioning jigs  90  are utilized when the terminal  22  of the bus bar  21  in the laminated body  20  is inserted into the terminal hole  41  in the first printed board  40 . As shown in  FIG. 4 , the positioning jigs  90  have a proximal end with a wide portion  90   a , which has substantially the same width as the great diameter portion  33   a  of the jig through-holes  33 , and a distal end with a narrow portion  90   b , which has substantially the same width as the small diameter portion  33   b  of the jig through-holes  33 . A support portion  90   c  is provided between the wide portion  90   a  and the narrow portion  90   b.    
   Next, a method for interconnecting the terminal  22  on the bus bar  21  in the laminated body  20  and the conductor  42  on the first printed board  40  will be described below. For ease of description, the method will be described based on the spatial orientation illustrated in  FIGS. 4A ,  4 B and  4 C, although the invention may be applied to other spatial orientations. 
   In a first step, as shown in  FIG. 4A , the laminated insulation plates  30 B to  30 D are arranged top side down, the positioning jigs  90  are inserted upward into the jig through-holes  33  in the insulation plates  30 B to  30 D and the positioning jig  90  is stopped when the positioning jigs  90  project from the jig through-holes  33  by a predetermined length. 
   In a second step, the positioning jigs  90  are inserted upward into the jig through-holes  33  in the outermost insulation plate  30 A, the support portions  90   c  of the positioning jigs  90  are brought into contact with a lower peripheral edge around the small diameter portion  33   b  in the jig through-holes  33 , and the positioning jigs  90  support the outermost insulation plate  30 A so that the plate  30 A is spaced away from the insulation plate  30 B by a predetermined distance. At this time, the protrusions  32  in the terminal through-hole  31  are opposed horizontally to the bulged portions  23  of the terminal  22  of the bus bar  21  and the terminal  22  is inserted upward into the terminal through-hole  31  in the outermost insulation plate  30 A. Alignment of the terminal  22  can be corrected by the protrusions  32  and bulged portions  23 . 
   In a third step, as shown in  FIG. 4B , the positioning jigs  90 , which project from the jig through-hole  33  in the outermost insulation plate  30 A, are inserted upward into the jig through-holes  43  in the first printed board  40 , which is in a top side down, thereby positioning the first printed board  40  with respect to the outermost insulation plate  30 A in a horizontal direction. Under this condition, the first printed board  40  is further pushed down so that the terminal  22  of the bus bar  2  is inserted upward into the terminal hole  41  in the first printed board  40 , thereby bringing the first printed board  40  into contact with the outermost insulation plate  30 A. 
   In a fourth step, as shown in  FIG. 4C , the positioning jigs  90  are extracted from the jig through-holes  43  and  33 , and the outermost insulation plate  30 A is moved toward and placed on the insulation plate  30 B. Then, the bulged portions  23  of the terminal  22  are shifted from the protrusions  32  in the terminal through-hole  31  in the outermost insulation plate  30 A in a vertical direction (which is parallel to the direction of insertion). 
   In the final step, the terminal  22  of the bus bar  21  is soldered on the conductor  42  of the first printed board  40 . 
   According to the above construction, when the terminal  22  of the bus bar  21  is inserted into the terminal hole  41  in the first printed board  40 , the positioning jig  90  supports the outermost insulation plate  30 A at a given position spaced from the insulation plate  30 B and the bulged portions  23  of the terminal  22  are aligned with the protrusions  32  in the terminal through-hole  31  in a vertical direction. Accordingly, the alignment of the terminal  22  of the bus bar  21  is corrected by the interaction of protrusions  32  and bulged portions  23 , and the terminal  22  of the bus bar  21  can be readily inserted into the terminal hole  41  in the first printed board  40 , thereby enhancing efficiency of the assembly operation. 
   After inserting the terminal  22  into the terminal hole  41  in the first printed board  40 , the positioning jigs  90  are extracted from the jig through-holes  43  and  33 , and the outermost insulation plate  30 A is moved toward and placed on the insulation plate  30 B. Then, the bulged portions  23  of the terminal  22  are shifted from the protrusions  32  in the terminal through-hole  31  in a vertical direction. Consequently, the terminal  22  is released from correction of alignment by the protrusions  32  and bulged portions  23 . Accordingly, even if the terminal through-holes  33  in the insulation plates  30  are shifted from the terminal hole  41  in the first printed board  40  in a horizontal direction on account of heat expansion or otherwise, it is possible for the end of the terminal  22  soldered to the printed board to follow the movement of the first printed board  40  without any interference with the protrusions  32 . This can prevent or reduce loads from being applied to the soldered part, which interconnects the terminal  22  and conductor  42  on the first printed board  40 , thereby reducing the possibility of cracks in the soldered part. 
     FIG. 5  shows another embodiment of the present invention. 
   In this embodiment, the protrusions  32  for correction of alignment are provided on the inner surface  31  of the terminal through-hole  31  in the outermost insulation plate  30 A and the inner surfaces  32   a  of the protrusions  32  are arranged to contact the outer surfaces  23   a  of the bulged portions  23  when viewed from above. 
   According to the above structure, in the condition in which alignment of the terminal  22  is corrected by the protrusions  32  and bulged portions  23 , the outer surfaces  23   a  of the bulged portions  23  of the terminal  22  contact with at least a part of the inner surfaces  32   a  of the protrusions  32 . Accordingly, it is possible to reliably correct the alignment of the terminal  22  and to readily insert the terminal  22  into the terminal hole  41  in the first printed board  41 . In this case, since the terminal  22  is released from correction of alignment after inserting the terminal  22  into the terminal hole  41  in the first printed board  40 , the possibility of causing any cracks in the soldered part may be reduced. 
   Since the other structures and operational effects are the same as those of the first embodiment, explanation of them is omitted by giving the same signs to the same elements. 
   Although the invention has been described with reference to specific embodiments, these embodiments should be viewed as illustrations and not limiting. Various modifications, substitutes and improvements are possible within the spirit or scope of the invention.