Electrical joint connector

Abstract: A joint connector (10) for connection to first, second and third exterior electrical connectors, e.g. in a wire harness, has an insulation plate (17) with parallel first bus bars (13) on one face providing a set of first connection tabs (13a) and parallel second bus bars (15) on a second face crossing the first bus bars (13). The second bus bars (15) at opposite ends thereof constitute second and third sets of connection tabs (15a,15b). The first and second bus bars are connected through holes in the insulation plate to form a circuit in the joint connector. The insulation plate and bus bars are in a casing. In use the first connection tabs (13a) connect to a first exterior connector, while the sets of second and third tabs (15a, 15b) connect to respectively second and third exterior connectors. The interior circuit is such that the circuit connections from the first connection tabs to the second connector tabs and the third connector tabs respectively are identical.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an electrical joint connector suitable to be incorporated in a wire harness to be placed on a vehicle body, such as an automobile body, and to an assembly of the joint connector and exterior connectors. Description of the Related Art If in a wire harness to be wired in a vehicle body, a splice treatment of the wiring cannot be made in an internal circuit of a junction box or the like, a joint connector is connected to the electrical wiring to make the splice. A joint connector 1 having the construction shown in Fig. 8 is used normally for this kind of purpose. The joint connector 1 accommodates joint bus bars 3, each having a tab 3a, provided in a casing 2. Terminals connected to the ends of the wires W branching from a wire harness W/H are inserted into a mating connector 4 and locked in position, and the connector 4 is inserted into a receiving opening 1a of the joint connector 1 and locked thereto to connect the connector 4 to the joint connector 1. In this manner, the electrical wires W are connected at the joint connector 1. The joint connector 1 and the connector 4 fitted to it are fixed to the wire harness W/H with a tape. The tabs 3a of the joint bus bars 3 are oriented in the same direction. In addition, the joint connector 1 has only one receiving opening 1a for the mating connector 4. Therefore, the mating connector 4 can be inserted from only one direction into the joint connector 1. For example, referring to Fig. 9, if it is necessary to connect wires of a trunk wire harness W/H-1 to a group of wires of a branch wire harness W/H-2 and a group of wires of a branch wire harness W/H-3, still only one mating connector 4 is connected to the joint connector 1, as described above. Therefore, the electric wires to be spliced are necessarily placed into one wire harness W/H and connected to the joint connector 1 as shown in Fig. 8 or two joint connectors are prepared to splice the wires. Accordingly, it is impossible to make an optimum design of the wire harness to be connected to the joint connector, further the position of installation of the joint connector is restricted. As such, the joint connector cannot be disposed at an optimum position in a space. Furthermore, because the joint connector 4 has two superimposed rows of terminals, it is voluminous. Thus, when the joint connector is installed on the trunk wire harness, e.g. taped up with the harness, the shape of the wire harness is irregular. Projecting portions are liable to be caught by other component parts when installing the trunk wire harness on a vehicle body. Consequently, wiring operability is poor. For example, paths for the trunk wire harness cannot be secured or the trunk wire harness cannot be inserted through a through-hole of a body panel. In addition, in the case where branch connectors to be connected to respective joint connectors have the same configuration, an erroneous connection may be made. To prevent such an erroneous connection, various countermeasures are made. For example, the colour of the connectors is varied. However, when the lengths of the branch wires are equal to each other, it is impossible to securely prevent the erroneous connection. EP-A-1071162 (Sumitomo Wiring Systems, Ltd.) published on 19 July 2000 discloses a junction connector for wire harnesses, having a flat casing with four connector-receiving locations spaced at 90° around it, for connection to four cables. In the casing are first and second sets of parallel bus bars arranged orthogonally on opposite sides of an insulating sheet. At selected crossing locations the bus bars of the respective sets are bent and joined by resistance welding at openings of the insulating sheet. US-A-2977672 shows a bonded wire circuit in which orthogonal arrays of conductors on opposite sides of an insulation sheet are interconnected at crossing points by welding them at apertures formed in the sheet. US-A-5655933 shows a system for distributing power between connectors in a connector raceway, for use for example in modular wall panels. Within a back shell or connector raceway there is a sub-assembly of three spaced apart connectors, each having a row of terminals. Within the housing, two of the connectors are connected to the third via insulated wires and a printed circuit board. SUMMARY OF THE INVENTION It is an object of the present invention to provide a joint connector, for a wire harness, which can be connected to mating connectors in a plurality of directions, can allow an optimum division of a wire harness, can be of small volume and thus can be installed at an optimum position in the space of a vehicle body, and can prevent erroneous connection. According to the invention, there is provided a joint connector for connection in use to first, second and third exterior electrical connectors to effect electrical connection between the first exterior connector and each of the second and third exterior connectors. The joint connector has an insulation plate having opposite first and second main faces. A plurality of first elongate bus bars are mounted on the first main face and extend in parallel in a first direction. First end portions of the first bus bars constitute a set of first connection tabs. A plurality of second elongate bus bars is mounted on the second main face of the insulation plate and extend parallel in a second direction crossing the first direction, so that the first and second bus bars, as seen in plan view on one of the main faces of the insulation plate, form a lattice array having intersection points of the bus bars. Second and third end portions of the second bus bars, respectively at opposite ends thereof, constitute respectively a set of second connection tabs and a set of third connection tabs. The first and second bus bars are electrically joined to each other at a plurality of the intersection points through holes in the insulation plate to form a predetermined interior circuit in the joint connector. A casing of flat shape accommodates the insulation plate and the first and second bus bars, and has first, second and third connector-receiving locations at which the exterior connectors can be fitted to make electrical connection. The first connection tabs are located in the first connector-receiving location to connect in use to the first exterior connector, and the sets of second and third connector tabs are located respectively in the second and third connector-receiving locations, which are on opposite sides of said casing, to connect in use to respectively the second and third exterior connectors. The interior circuit is such that the circuit connections from the first connection tabs to the set of second connector tabs and the set of third connector tabs respectively are identical. This allows the second and third connectors to be interchangeably attached at the second and third connector-receiving locations, so that erroneous connection can be avoided. The second and third connector-receiving locations have substantially identical shape and configuration but are mutually inverted with respect to the casing, while the first connector-receiving location has a substantially different shape and configuration. The above construction allows the connector-receiving locations to be formed in different directions e.g. the first location may be on a side of the casing perpendicular to the two opposite sides of said second and third locations, so that the casing is T-shaped. Accordingly, it is unnecessary to bundle electric wires to be spliced through the joint connector into one wire harness, but it is possible to design a circuit according to a wiring configuration of the wire harness and according to where there is a space for the joint connector. Consequently, it is possible to accomplish an optimum division of the wire harness. Preferably, the first and second bus bars are bent downward and upward respectively at their portions connected through holes in the insulation plate. Then, the apex of the bent portion of the first bus bar and that of the bent portion of the second bus bar are brought into contact in the through-hole of the insulation plate. In this state, resistance welding is carried out to connect the bus bars to each other. It is possible to weld bus bars laminated one upon another in three or more layers. The insulation plate has the bus bars disposed on its upper and lower surfaces. Thus, it is possible to accommodate the plate in the low flat casing. Thus, the joint connector is not voluminous. Therefore, when the joint connector is installed on the peripheral surface of the trunk electric wire of the wire harness, this portion of the wire harness does not project much, which facilitates an operation of wiring the wire harness on a vehicle body. BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention will now be described by way of non-limitative example with reference to the accompanying drawings, in which:- Fig. 1 is a plan view showing a joint connector which is an embodiment of the present invention, with its upper casing part removed. Fig. 2 is a schematic view showing the directions in which the joint connector of Fig. 1 and wire harnesses are connected to each other. Figs. 3(A), 3(B) and 3(C) are plan views showing the process of forming the circuit of the joint connector of Fig. 1. Fig. 4(A) is a plan view of the joint connector of Fig. 1. Fig. 4(B) is a right side view of the joint connector of Fig. 1. Fig. 4(C) is a sectional view taken along line C-C of Fig. 4(A). Fig. 5(A) is an enlarged plan view showing a connection between a bus bar and a carrier in the process of making the joint connector of Fig. 1. Fig. 5(B) is a front view of Fig. 5(A). Fig. 6 is an enlarged sectional view showing a portion of each of upper and lower bus bars which are to be welded together in the process of making the joint connector of Fig. 1. Fig. 7(A) is a diagram showing a normal connection state of the connector of Fig. 1. Fig. 7(B) is a diagram showing an erroneous connection state of the connector of Fig. 1. Fig. 7(C) is a diagram showing a connection state of the connector of Fig. 1 in the case where the connector is inverted. Fig. 8 is a schematic perspective view showing a conventional joint connector. Fig. 9 is a schematic view showing a problem with the conventional joint connector. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Figs. 1 to 7 show a joint connector 10 embodying the invention having a generally planar casing 20 which is relatively thin in one dimension and consists of a lower casing part 11 and an upper casing part 12 and incorporates a bus bar circuit plate 30. The casing 20 is of moulded plastics material. The casing 20 has a first connector socket 22 projecting from a first edge of the outer surface of a central portion 21 which is of approximately square shape and contains the circuit, a second connector socket 23 projecting from another edge perpendicular to the first edge, and a third connector socket 24 projecting from another edge perpendicular to the first edge. Thus, the casing 20 overall is approximately T-shaped. As shown in Fig. 3, the bus bar circuit plate 30 has an insulation plate 17 with parallel discrete elongate flat sheet metal bus bars 13 arranged on its upper surface extending in parallel in a first direction (Y-direction) and spaced apart at regular intervals, and parallel discrete sheet metal bus bars 15 having the same configuration as that of the bus bars 13 arranged on its lower surface extending in parallel in a second direction (X-direction) orthogonal to the first direction and also spaced at regular intervals. The bus bars 13,15 need not be equally spaced apart. More specifically, the upper bus bars 13 extending in the Y-direction and the lower bus bars 15 extending in the X-direction are fitted in respective grooves 17a formed on the upper and lower surfaces of the insulation plate 17. That is, as seen in plan view, the bus bars 13 and 17 crossing each other form a lattice on the insulation plate 17. The bus bars 13,15 are connected to each other at some of their intersection positions P1 - P7 shown in Fig. 3, to form the desired internal circuit. As shown in Fig. 6, through-holes 17a are formed in the insulation plate 17, at which the upper and lower bus bars 13,15 are bent towards each other in the shape of an approximately circular arc. The apexes of the bent portions of the bus bars are brought into contact in the through-holes 17a, and joined by resistance welding to form welds T. The formation of the bends in the bus bars 13,15 may be carried out before or after the bus bars are placed on the plate 17, preferably before. To assemble the bus bar circuit plate 30, as shown in Fig. 3, the set of upper bus bars 13 and the set of lower bus bars 15 are arranged on the insulation plate 17, with one end of each upper bar 13 connected to a carrier 50 and both ends of each lower bar 15 connected to respective carriers 51. Resistance welding at the required positions of the upper and lower bus bars 13,15 is performed. Then, the carriers 50,51 are broken off from the bus bars 13,15. V-shaped grooves 50a,51a (see Fig. 5) are formed at the connection of the bus bars 13,15 to the carriers 50,51 so that an operator can break off the carriers 50,51 from the bus bars 13,15 by folding at the grooves 50a,51a once or twice. After removal of the carriers 50,51 the bus bars are held in place by their resistance welding connections. One end of each bus bar 13 forms a tab 13a. The opposite ends of each bus bar 15 form tabs 15a,15b. The tabs 13a project in the Y-direction into the first connector socket 22. The tabs 15a project in the X-direction into the second connector socket 23, while the tabs 15b project into the third connector socket part 24. The first connector socket 22 in use receives a connector 100 at the end of trunk electrical wiring W/H-1 of a wire harness. The second connector socket 23 receives a connector 200 at the end of first branch electrical wiring W/H-2 of the wire harness. The third connector socket 24 receives a connector 300 at the end of a second branch electrical wiring W/H-3 of the wire harness. The connectors 100,200,300 have terminals within them which engage and connect to the tabs at the end portions of the respective sets of bus bars 13,15. The bus bars 13 in the Y-direction and the bus bars 15 in the X-direction are not cut at any points. Thus, the tabs 15a,15b of each X-direction bus bar 15 are connected with the same wire of the trunk electric wiring W/H-1 of the wire harness through one Y-direction bus bar 13. That is to say, the same circuit connection is obtained regardless of whether the particular connector fits in the second or third connector socket 23, 24. As shown in Fig. 4(C), the second connector socket 23 has the same configuration as that of the third connector socket 24 but the two are mutually inverted. A connector-locking claw 23a is formed on the second connector socket 23 at its upper side. A connector-locking claw 24a is formed on the third connector socket 24 at its lower side. The connectors 200,300 connected to the branch wirings W/H-2, W/H-3 respectively have the same configuration. The connectors 200,300 each have, on a corresponding surface, a locking groove (not shown) to which the claws 23a,24a lock. The connector 100 which fits in the first connector socket 22 has a configuration different from that of the connectors 200 and 300. Referring to Fig. 7(A), in the normal fitting state the connector 100 fits on the first connector socket 22 of the joint connector 10, the connector 200 (locking groove upward) fits on the second connector socket 23, and the connector 300 (locking groove downward) fits on the third connector socket 24. Referring to Fig. 7(B), let it be supposed that erroneously the connector 300 is fitted on the second connector socket 23 and that the connector 200 fitted on the third connector socket 24. In this case, in order to lock the claw 23a of the second socket 23 and the claw 24a of the third socket 24 to the respective locking grooves of the connectors 300,200, each of the connectors 300,200 must be inverted. Consequently, the same circuit connections as in the normal circuit shown in Fig. 7(A) are obtained. Referring to Fig. 7(C), let it be supposed that the joint connector 10 is inverted, so that the third socket 24 now occupies the position of the second socket 23, and the second socket 23 occupies the position of the third socket 24. As the circuit of the second socket 23 is the same as that of the third socket 24, the same connections are achieved. Therefore, the connectors 200,300 can be connected in the normal state. To summarise, with the invention, even though a connector connected to a wire harness is erroneously fitted on the joint connector an erroneous circuit is not obtained. That is, the connector is normally connected to the joint connector. Further, because the connector socket of the joint connector can be set in different directions, it is possible to make an optimum division of the wire harness according to a wiring mode and set a branching position according to the space for installing the wire harness. Further, because the internal circuit of the joint connector is a combination of elongate bus bars, it is possible to manufacture the bus bar assembly simply and inexpensively. In addition, the joint connector is thin. Thus, the joint connector fixed to the peripheral surface of the wire harness with a tape is not bulky, so that the wire harness can be wired on a vehicle body with a high wiring operability.

Claims: A joint connector (10) for connection in use to first, second and third exterior electrical connectors (100,200, 300) to effect electrical connection between said first exterior connector (100) and each of said second and third exterior connectors (200,300), having an insulation plate (17), a plurality of first elongate bus bars (13) mounted on a first main face of the plate (17) and extending in parallel in a first direction, and providing a set of first connection tabs (13a), a plurality of second elongate bus bars (15) mounted on a second main face of the plate (17) and extending parallel in a second direction crossing said first direction, whereby said first and second bus bars as seen in plan view on one of said main faces form a lattice array having intersection points of the bus bars, opposite end portions of said second bus bars constituting respective sets of second connection tabs (15a) and third connection tabs (15b), said first and second bus bars being electrically joined to each other at a plurality of said intersection points through holes (17a) in said insulation plate (17) to form a predetermined interior circuit in the joint connector, and a casing (21) of flat shape accommodating said insulation plate and said first and second bus bars and having first, second and third connector-receiving locations (22,23,24) at which said exterior connectors are fitted in use of the joint connector, wherein: said first connection tabs (13a) are located in said first connector-receiving location (22) to connect in use to said first exterior connector (100), and said sets of second and third connector tabs (15a) are located respectively in said second and third connector-receiving locations (23,24), which are on opposite sides of said casing, to connect in use to respectively said second and said third exterior connectors (200,300), said interior circuit is such that the circuit connections from said first connection tabs (13a) to said set of second connector tabs (15a) and said set of third connector tabs (15b) respectively are identical, and said second and third connector-receiving locations (23,24) have substantially identical shape and configuration but are mutually inverted with respect to said casing (21), said first connector-receiving location (22) having a different shape and configuration. A joint connector according to claim 1, wherein each of said second and third connector-receiving locations (23,24) has a locking claw for locking to an exterior connector received therein, said locking claws being in mutually inverted positions and orientations. An assembly comprising a joint connector according to either of claims 1 or 2 and first, second and third exterior connectors (100,200,300) adapted to be received at said first, second and third connector-receiving locations (22,23,24) respectively, wherein said second and third exterior connectors are substantially identical and are interchangeably receivable at said second and third connector-receiving locations (23,24). An assembly according to claim 3, wherein said first, second and third exterior connectors are each connected to wiring of a wire harness.

Inventors: KASAI KOJI, KASAI, KOJI, Kasai, Koji, Sumitomo Wiring Systems, Ltd.
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 2001
Main classification: H01R9
IPC codes: H01R31, H02G15, H02G3, H01R9