Electrical connection box containing bus bars

Abstract: An electric connection box, for use in vehicles etc., has vertical parallel bus bars (15a-15j) which permit a variety of bus bar circuits to be easily made. The electric connection box (11) has upper and lower casing parts (12,13) containing the vertical bus bars (15a-15j) which may be identical, each having a sheetform bar body (21), plural tab terminals (22), and plural pressure contact blades (23). The tab terminals (22) project at regular intervals on one side of the bus bar body (21) and the pressure contact blades (23) project on the opposite side. To connect the bus bars electrically to form a bus bar circuit, wires (31) are brought into pressure contact with the appropriate pressure contact blades (23).

Description: FIELD OF THE INVENTION The present invention relates to an electrical connection box containing bus bars, suitable for use for example in vehicles, such as automobiles. The invention also relates to a method of making such a box. BACKGROUND OF THE INVENTION An electrical connection box described in US-A-5624280, corresponding to JP-A-135717, is a branched connection box, having an upper case part and a lower case part which are connected, and a plurality of parallel vertical bus bars accommodated in the case. These vertical bus bars are equipped with a plurality of terminals (tab terminals) projecting upwardly and downwardly in the box. The tab terminals project through the case into connector-receiving recesses provided on each case part, for connection with the terminals of connectors to be fitted to the box. When using such electrical connection boxes for different vehicle types, circuit connections of the bus bars are required to be varied according to the respective circuit arrangements of the vehicles. However, when making the bus bar connections in this box, the wires have to be connected to the respective tab terminals projecting from the terminal holes of the connectors. For this reason, there is a necessity to fix to the tip of the wire a connection terminal that can be engaged with the tab terminal. This requires complicated work in connection of the wires, and uses a large number of parts. EP-A-729200 discloses an electrical connection box having connected upper and lower casing parts housing an internal circuit constituted by internal wires and first and second types of pressure contact terminals. One of the casing parts has connector-receiving regions to receive exterior connector members. The first pressure contact terminals are planar and arranged vertically, each having a pressure contact blade which engages an internal wire and a tab which projects into the connector-receiving region. The second pressure contact terminals have three pressure contact blades arranged in a row and joined by a horizontal body portion and a tab which projects into the connector receiving region. Wires of a wiring harness project into the connection box and are connected end-to-end to the internal wires by the pressure contact blades of the second pressure contact terminals. SUMMARY OF THE INVENTION The object of the present invention is to provide an electric connection box having bus bars, which allows easy adaptation and choice of the bus bar circuit connections. According to the invention there is provided an electrical connection box having connectable upper and lower casing parts defining when connected an interior space, and a plurality of bus bars arranged within said interior space in a side-by-side array with respective main body portions of planar sheet form arranged vertically in respective vertical planes parallel to each other and extending alongside each other in a horizontal longitudinal direction, the upper casing part having connector regions to receive exterior connector members in use, each bus bar having a plurality of tab terminals projecting vertically away from the bus bar main body portion on the upper side thereof and protruding into said connector regions, and each bus bar having at least one pressure contact blade projecting downwardly from the bus bar main body portion for making pressure contact with electrical wires. In the electrical connection box of the invention, an electrical wire making contact with the pressure contact blades can extend linearly in the orthogonal direction. In another aspect, the invention provides a method of making an electrical connection box, as set out in claim 8. In this specification, including the claims, the directional terms "upper", "lower", "vertically" etc. are used relatively to each other for convenience of explanation and definition. The connection box of the invention can be assembled and used in any orientation appropriate to a particular assembly process or use. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be described by way of non-limitative example with reference to the accompanying drawings, in which:- Fig. 1 is an exploded perspective view of an electrical connection box of one embodiment of the invention; Fig. 2 is an exploded perspective view from below of the electrical connection box of Fig. 1; Fig. 3 is a sectional view on the line A-A in Fig. 1; Fig. 4 is the same sectional view as Fig. 3 showing the assembled state of the box; Fig. 5 is a perspective view from below of a vertical bus bar of the same embodiment; Fig. 6 is a perspective view of an example of modification of the bus bar circuits; Fig. 7 is a front view of a vertical bus bar of another embodiment of the invention; Fig. 8 is a front view of a vertical bus bar of yet another embodiment of the invention. DETAILED DESCRIPTION OF THE EMBODIMENTS One embodiment of the present invention is described in detail below with reference to Figs. 1 to 6. As shown in Figs. 1 and 2, the electrical connection box 11 is constituted by an upper casing part, here called upper case 12, a lower casing part, here called lower case 13, and an array 14 of bus bars. The upper case 12 and the lower case 13 are respectively made, each in one piece, of synthetic resin, and are mutually engageable to connect them together. In detail, on each side of the upper case 12, there is formed a first engaging part 12a, and on the inside of the lower case 13 there are formed complementary second engaging parts 13a which connect in snap-fit manner with the first engaging parts 12a. The array 14 of bus bars is constituted by ten vertical bus bars 15a-15j each formed of a metal sheet, as one piece. The respective bus bars 15a-15j in this embodiment all have the same shape and configuration, and are formed by punching and bending metal sheet. Each bus bar 15a-15j has a plate-form or sheet-form planar main bus bar body 21, plural tab terminals 22, and plural pressure contact blades 23 which are coplanar with the body 21. The tab terminals 22 project on one side of the bus bar body 21 and are spaced at predetermined regular intervals. The pressure contact blades 23 project on the opposite side, again at equal intervals, at locations horizontally offset from the tab terminals 22. The tab terminals 22 and pressure contact blades 23 thus alternate along the bus bar body 21. On the same side as the pressure contact blades 23 the bus bar body 21 has plural projections 21a at predetermined intervals, whose lower edges are flush with the bottom face of the upper case 12 when the bus bars 15a-15j are completely inserted in the upper case 12. On the top face of the upper case 12, there are formed a plurality of connector housings 24, in the form of recesses defined by upstanding walls. These receive exterior connectors in use. Also, as shown in Figs. 2 and 3, on the bottom face side of the upper case 12, there are bus bar receiving grooves 25 defined by separating walls 25a, which accommodate the bus bars 15a-15j at equal spacings and in parallel. As shown in Fig. 1, on the upper face of the lower case 13, corresponding to the grooves 25 of the upper case there are bus bar accommodating recesses or grooves 26 defined by separating walls 26a. Additionally, on the upper face of the lower case 13, there are a plurality of ribs 27 higher than the walls 26a and linearly extending orthogonally to the grooves 26 at predetermined intervals, at the positions corresponding to the projections 21a of the bus bars 15a-15j when installed. In the electrical connection box 11, each bus bar 15a-15j is accommodated upright in a groove 25 with the tab terminals 22 directed upwardly, as shown in Fig. 1 to Fig. 4. As shown in Fig. 3, in the bottom wall of each connector housing 24 there are a plurality of through holes 24a, through which the tab terminals 22 are thrust, while the pressure contact blades 23 of the bus bars are arranged in rows in the direction orthogonal to the direction of the bus bar bodies 21. When each bus bar 15a-15j is fully received in the groove 25, the lower edge of each projection 21a is flush with the bottom face of the upper case 12 (i.e. the lower edges of the walls 25a and the lower edge of the peripheral wall of the upper case 12), which enables easy observation that each bus bar is correctly located. To establish any particular desired arrangement of the bus bar circuits by electrically connecting the different bus bars 15a-15j, electrical wires 31 are brought into pressure contact with the desired pressure contact blades 23, as shown in Fig. 6. Each wire 31 is, for example, a single core wire. The wires are brought into pressure contact with the desired pressure contact blades 23 by a pressure contact machine (not shown), and pressed into the slots in the blades 23 to fix the wires in position and establish electrical connection. The wires of the desired bus bars 15a-15j are thus electrically connected. Since the blades 23 are in rows, the wires 31 are laid linearly in the direction orthogonal with the direction of the bus bar bodies 21. Thereafter the lower case 13 is fitted to the bottom side of the upper case 12, so that, as shown in Fig. 4, each rib 27 of the lower case 13 comes into direct contact with the rows of projections 21a of bus bars 15a-15j. Thus, if the bus bars 15a-15j are not fully accommodated in the grooves 25, the projections 21a are pressed by the ribs 27 to bring the bus bars 15a-15j to their correct positions on fitting of the lower case 13. The bus bars 15a-15j and the wires 31 are now accommodated in the interior space of the electric connection box 11. Figs. 2 and 3 shows that the separating walls 25a have pairs of downward projections 25b at the locations of the pressure contact blades 23. The projections 25b support the blades 23 laterally, e.g. during the operation of inserting the interconnecting wires 31. Furthermore, when the lower case 13 is connected to the upper case 12, the lower ends of the pressure contact blades 23 are received in the grooves 26, so that the separating walls 26a also act to support the pressure contact blades 23. In this embodiment there are no terminals (such as tab terminals) projecting from the bus bars 15a-15j through the lower case 13, which therefore acts as a base of the connection box 11, enclosing and protecting the wires 31 and the pressure contact blades 23. The wires and contact blades 23 are thus well protected and supported in position, against external forces, e.g. when connectors are pushed onto the tab terminals 22, ensuring high reliability of the internal wiring of the connection box. By cutting to eliminate selected parts of bus bars 15a-15j, it is possible to adapt the bus bar circuits to a particular desired arrangement, with wide choice. For example, the bus bar body 21 is cut to eliminate a portion shown by the broken lines C1 in Fig. 5, to separate the bus bar into two parts which are electrically isolated. Various forms of the bus bars as shown for example in Fig. 6 are obtainable. Furthermore, if it is wanted to make mutual electrical connection between non-adjacent bus bars, for example as shown in Fig. 6 to connect electrically the bus bar 15f and the bus bar 15j, selected pressure contact blades 23 in one transverse row thereof are cut off to remove them, e.g. by cutting on the line C2 in Fig. 5. A wire 31 is brought into pressure contact with the remaining pressure contact blades 23 of the bus bars 15f,15j. Various bus bar circuits are thus obtainable for example as shown in Fig. 6. In this embodiment, the following effects can be obtained:- (1) As the bus bars 15a-15j are provided with the pressure contact blades 23, when an electrical wire 31 is brought into pressure contact with, for example, the pressure contact blades 23 of two adjacent bus bars, the two bus bars can be electrically connected. In other words, there is no necessity as in a conventional electric connection box to fix connection terminals engageable with the tab terminals 22 to the ends of the electric wires 31. Accordingly, it is easy to carry out electrical connection between the different bus bars. (2) In each of the bus bars 15a-15j, no tab terminal 22 is provided on the side where the pressure contact blade 23 is provided. Accordingly, even when the tab terminals 22 are in a crowded arrangement, the electrical wire 31 can be easily brought into contact with the pressure contact blade 23. (3) When the electrical wire 31 is brought into pressure contact with the pressure contact blades 23 of the bus bars 15a-15j, the wire 31 can have a linear form (straight line). Accordingly, the wire 31 can be reliably brought into contact with the blades 23. Also, in addition, as the bus bars 15a-15j are accommodated in the grooves 25 in parallel, the position of each pressure contact blade 23 can be easily computed. Therefore, positioning of the wires 31 can be easily done automatically. Moreover, as a plurality of the blades 23 are formed on each of the bus bars 15a-15j, the wires 31 can be brought into pressure contact with the desired bus bars 15a - 15j in various modes. The contact blades 23 are at equal distances apart, so that wire positioning by the pressure contact machine can be easily performed. (4) In the known electrical connection box as described above, because wires in the box cannot be used to make electrical connection between the different bus bars, it is necessary to connect the electric wires to the tab terminals outside the box. Accordingly, when mounting the electrical connection box in a vehicle, the wires become an obstacle. For this reason, space for accommodating the wires is required, and it is necessary to use a large space for mounting the electric connection box in a vehicle. In contrast, in the electrical connection box 11 of this embodiment, the wires 31 are accommodated in the box, and not exposed outside the box. For this reason, there is no requirement for space for the wires 31 in the vehicle, and there is no necessity to use a large space for mounting the electric connection box 11 in the vehicle. In addition, as the wire 31 is not exposed outside the box, improved waterproof performance is obtained. Moreover, due to no intervention of connection terminals between the wires and the bus bars 15a-15j, increase of electric contact resistance can be prevented, and reliability can be improved. The embodiment of the present invention shown may be modified as follows: In the embodiment, tab terminals 22 project on only one side of the bus bars 15a-15j, and the pressure contact blades 23 project on only the other side. However, as shown in Fig. 7, at the side at which the pressure contact blades 23 project, tab terminals 22 may be provided, e.g. to project symmetrically as shown in the figure. Also, as shown in Fig. 8, at the side at which the pressure contact blades 23 project, tab terminals 22 may be provided staggered with respect to the terminals 22 at the upper side, and pressure contact blades 23 may be provided on both sides. With such an arrangement the connector housings 24 may be formed on both the upper case 12 and the lower case 13, so that the number of the connectors fitted to the connection box 11 can be increased. Furthermore, by providing pressure contact blade 23 on both sides of the bus bar body 21, locations for wires 31 can be increased. The pressure contact blades 23 are arranged in rows orthogonal to the direction of extension of the bus bar body 21, but this is not necessary. The projection 21a provided on the bus bar body 21 may be omitted. In this case, a pressure contact blade 23 can be formed in place of the projection 21a. The ribs 27 provided on the top face of the lower case 14 may be omitted. When such provision is made, the lower case 14 can have a simple construction. In the foregoing embodiments all the bus bars 15a-15j are formed with the same configuration. However, these bus bars 15a-15j, may be of mutually different configurations. In the embodiment of Figs. 1 to 6, because there is no projection of tab terminal to the side provided with the pressure contact blades, the tab terminals do not become obstacles in making pressure contact of wires with the pressure contact blades. For this reason, the wires can be easily brought into pressure contact with the pressure contact blade. Furthermore, the wires may extend in straight lines orthogonally to the bus bars. For this reason, the wires can be reliably brought into pressure contact with the pressure contact blades. Moreover, as the bus bars are disposed parallel with one another, the position of each pressure contact blade can be easily computed. Consequently, in carrying out pressure contact of the electric wires automatically using a pressure contact machine, position setting of the electric wires to the individual pressure contact blades can be easily achieved. In another embodiment, when the connector-receiving parts 24 are provided on both the first and the second cases and the tab terminals project on both sides of the bus bar body, the numbers of the connectors attached to the connection box can be increased. Also, when the pressure contact blades are provided on both sides of the bus bar body, the locations of the wires 31 can be increased. 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 scope of the invention.

Claims: An electrical connection box (11) having connectable upper and lower casing parts (12,13) defining when connected an interior space, and a plurality of bus bars (15a-15j) arranged within said interior space in a side-by-side array with respective main body portions of planar sheet form arranged vertically in respective vertical planes parallel to each other and extending alongside each other in a horizontal longitudinal direction, the upper casing part (12) having connector regions (24) to receive exterior connector members in use, each bus bar (15a-15j) having a plurality of tab terminals (22) projecting vertically away from the bus bar main body portion on the upper side thereof and protruding into said connector regions (24), and each bus bar (15a-15j) having at least one pressure contact blade (23) projecting downwardly from the bus bar main body portion for making pressure contact with electrical wires, wherein the said pressure contact blades (23) of the respective bus bars (15a-15j) are arranged in at least one row orthogonal to said horizontal longitudinal direction of said bus bar main body portions. An electrical connection box according to claim 1, wherein each said bus bar (15a-15j) has a plurality of said pressure contact blades (23) which are coplanar with said main body portion thereof, the pressure contact blades (23) of the bus bars being in a plurality of rows orthogonal to the said horizontal longitudinal direction of the bus bar main body portions. An electrical connection box according to any one claim 1 or 2, wherein said bus bars (15a-15j) are located in parallel grooves (25) of said upper casing part, said grooves (25) being defined by separating walls (25a) which have projections (25b) lying adjacent said pressure contact blades (23) for support thereof. An electrical connection box according to any one of claims 1 to 3, wherein said bus bars (15a-15j) have no terminals projecting downwardly through said lower casing part (13), said lower casing part (13) thus constituting a base enclosing and protecting said pressure contact blades (23) and electrical wires (31) connected to said pressure contact blades (23). An electrical connection box according to any one of claims 1 to 4, wherein said lower casing part (13) has recesses (26) which receive said pressure contact blades (23), whereby said pressure contact blades are supported against bending in said lower casing part. An electrical connection box according to any one of claims 1 to 5, wherein each said bus bar (15a-15j) has a plurality of abutment elements (21a) arranged to abut cooperating abutment surfaces (27) of at least one of said upper and lower casing parts. An electrical connection box according to any one of claims 1 to 6 wherein said connector regions (24) on said upper casing part (12) are recesses defined by upstanding walls on said upper casing part, said recesses being separated at their bottom ends from said interior space by a wall having apertures (24a) through which said tab terminals (22) protrude. A method of making an electrical connection box, comprising the steps of (i) providing connectable upper and lower casing parts (12,13) defining when connected an interior space, said upper casing part (12) having connector regions (24) to receive exterior connector members in use, (ii) inserting into respective predetermined holding locations of one of said casing parts (12,13) a plurality of bus bars (15a-15j) which each have a main body portion of planar sheet form, the main body portions when inserted being arranged vertically and in respective vertical planes parallel to each other and extending alongside each other in a horizontal longitudinal direction, said bus bars (15a-15j) when inserted each having a plurality of tab terminals (22) on the upper side of said bus bar main body portion which protrude into said connector regions (24) and at least one pressure contact blade (23) projecting downwardly from said bus bar main body portion, said pressure contact blades (23) of the respective bus bars (15a-15j) when inserted being arranged in at least one row orthogonal to said horizontal longitudinal direction of said bus bar main body portions, (iii) before or after step (ii), establishing electrical connections between said bus bars (15a-15j) in a predetermined manner by means of electrical wires (31) making pressure contact with said pressure contact blades (23), and (iv) connecting said upper and lower casing parts together so as to secure said bus bars (15a-15j) and wires (31) in said interior space.

Inventors: KASAI KOJI, KASAI, KOJI, Kasai, Koji, Sumitomo Wiring Systems, ltd
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 2000
Main classification: H01R9
IPC codes: H02G3, H01R9