Electrical connection box

Abstract: To provide an electrical connection box which can easily respond to a change in the circuit construction among different types of vehicles and among different grades of the same type of vehicles, and can be generally used, an internal circuitry of an electrical connection box is divided into a common circuitry 1 and a special circuitry 2. A conductive layer on which the common circuitry 1 is formed and another conductive layer on which the special circuitry 2 is formed are arranged one over the other at different levels in a casing of the electrical connection box. The common circuitry 1 comprises flat busbars 10, whereas the special circuitry 2 preferably comprises a wire, longitudinal busbars 20, or a flat circuit 25 such as a flexible printed circuit (FPC) or a printed circuit board (PCB). The common circuitry 1 and the special circuitry 2 may alternatively be formed of the same conductive material.

Description: The present invention relates to an electrical connection box for automotive vehicles and is particularly designed to, when an internal circuitry of the electrical connection box partially differs among different types of vehicles and among different grades of the same type of vehicles, enable the use of the same electrical connection box only by changing a different portion of the internal circuitry. An electrical connection box used to connect a wiring harness for an automotive vehicle with a variety of wiring devices is adapted to realize a rational and economical junction connection of the wiring by concentrating points of junction connection on one location. A variety of types of such electrical connection boxes are being developed as the wiring harness is made more compact. Generally, flat busbars formed of a conductive metal plate in conformity with a circuit pattern are used as an internal circuitry of an electrical connection box such as a junction box. A plurality of flat busbars are arranged one over another at a plurality of levels to compact the electrical connection box. The busbars are formed by suitably bending the punched conductive metal plate. Accordingly, upon a change in the circuit pattern, a mold used to punch the metal plate needs to be changed, and the way the punched metal plate is bent differs. This leads to more labor and an increased cost. In order to cope with the above problem, Japanese Unexamined Utility Model Publication No. 2-136989 discloses an electrical connection box in which a large current circuitry formed of busbars and a small current circuitry formed of wire and cramping terminals are accommodated at different levels. Further, Japanese Unexamined Utility Model Publication No. 1-166419 discloses an electrical connection box in which a supply side circuitry connected with fuses F is formed of busbars indicated by bold lines, and a load side circuitry is formed by a combination of a wire and cramping terminals indicated by thin lines in Fig. 6. The internal circuitry of the electrical connection box differs among different types of vehicles and among different grades of the same type of vehicles. If the internal circuitry is divided into the large current circuitry and the small current circuitry as disclosed in the above publication No. 2-136989, the construction of the large current circuitry may differ since both necessary and unnecessary circuits thereof differ among different types of vehicles and among different grades of the same type of vehicles. Similarly, the construction of the supply side internal circuitry disclosed in the above publication No. 1-166419 may also differ. Therefore, even if the internal circuitry is divided into the large current circuitry and the small current circuitry and the large current circuitry is formed by the busbars, or even if the internal circuitry is divided into the supply side circuitry and the load side circuitry and the supply side circuitry is formed by the busbars, the circuit construction differs among the different types and the different grades of vehicles. Therefore, there are many cases where new busbars have to be formed. On the other hand, even in the small current circuitry formed by the wire and the cramping terminals or even in the load side circuitry, there are small current circuits required for all types and all grades of vehicles at the load side. These circuits include, for example, circuits connected with lamps such as head lights, and a circuit connected with a horn (honker). These circuits are common circuits which are required for any vehicle. Thus, there is no problem in forming these common circuits by busbars. The formation of these circuits by wire and cramping terminals instead of the busbars may result in more labor to arrange the wire and to mount the cramping terminals. US 5,207,587 discloses an electrical distribution center electrically connecting electrical and electronic devices and electrical connectors of wiring harnesses. The electrical distribution center comprises a main bus plate including a plurality of stamped metal circuit components that are insert molded in an insulation board. The stamped metal circuit components have a plurality of male blade terminals that project outwardly of the insulation board and include wire receiving slots. The main bus plate is sandwiched between upper and lower bus plates each including a plurality of wire circuit components arranged in slots of an insulated routing board. The wire receiving slots of the male blade terminals receive the wire circuit components of the upper and lower bus plates. In this arrangement the electric circuit is divided into a high current circuit and a low current circuit. The high current circuit is formed by the stamped metal circuit components while the low current circuit is formed by the wire circuit components. As discussed above both the high current circuit and the low current circuit comprise parts which are common for all vehicles and special parts which differ among different types and different grades of vehicles. Therefore, there are many cases where new stamped metal circuit components have to be formed which results in higher production costs. US 5,040,996 discloses a central circuit arrangement for motor vehicles which comprises a layered conductor packet consisting of flat printed circuit boards superimposed in various planes and mutually separated by insulating boards. An electric distributing board is inserted between two neighboring insulating boards. Pin strips for contacting the printed circuit boards adjacent to the insulating boards are mounted on the distributing board. The pins can be selectively connected with straps to form a further electrical circuit. US 4,689,718 discloses an automobile junction box which is programmable in relation to vehicle options. The junction box consists of two stacked circuit boards. The circuit boards are provided with several terminals for connection with external connectors and receiving external electrical components like diodes, resistors and the like. In such an arrangement a change of the circuit pattern, for example for different car models is expensive, since the printed circuit boards have to be changed. Further, also a change of the arrangement of the terminals for connecting external electrical components with the junction box is difficult, since the terminals are soldered onto the printed circuit board. It is the object of the invention to provide an electrical connection box which can be commonly used for different types of vehicles and different grades of the same type of vehicles by partially changing a circuitry and which allows to easily connect external terminals with an internal electrical circuit. This object is accomplished by an electrical connection box as defined in claim 1. Preferred embodiments are defined in the dependent subclaims. According to the invention, an internal circuitry is divided in a different manner from the prior art. Specifically, it is divided into a common circuitry which is needed independently of the type and the grade of the vehicle and a special circuitry which differs depending upon the type and the grade of the vehicle. The electrical connection box can be used for any vehicle only by changing the special circuitry. Accordingly, the internal circuitry can be mounted in the electrical connection box while using the common circuitry as it is independently of the type and the grade of the vehicle and changing only the special circuitry in conformity with the type and grade of the vehicle. Therefore, the electrical connection box can easily be used for different types and different grades of vehicles, and can be designed with an enhanced degree of freedom. Preferably, the common circuitry comprises flat busbars, and the special circuitry comprises longitudinal busbars. If the flat busbars are used for the common circuits, it obviates the need to separately form the busbars for different types and different grades of vehicles. Costs for the molds used to form the busbars can be reduced. Alternatively, the common circuitry and the special circuitry may be formed of the same kind of conductive material, i.e. longitudinal busbars arranged in a vertical direction. If the common circuits are formed not by the flat busbars which are formed by punching and bending a metal plate in conformity with the circuit pattern, but by wires, by longitudinal busbars or by flat circuits, the costs for the molds used to form the busbars can be reduced, and the degree of freedom in design can be enhanced. Further, the electrical connection box can have a simple internal construction, and can be assembled with an improved efficiency. The longitudinal busbars are preferably narrow rectangular busbars formed of a conductive plate which are disposed such that their surfaces extend in the vertical direction. External terminals may be directly engaged and connected with either ones of the upper and lower edges of the longitudinal busbars. Alternatively, cramping terminals may be connected with either ones of the upper and lower edges of the longitudinal busbars and also be connected with external terminals. These and other objects, features and advantages of the present invention will become more apparent upon a reading of the following detailed description and accompanying drawings in which: FIG. 1A is a schematic diagram showing a circuit construction of the invention, and FIG. 1B is a table showing standards for distinguishing a common circuitry and a special circuitry, FIG. 2 is an exploded perspective view of a first embodiment of the invention, FIG. 3 is an exploded perspective view of a second embodiment of the invention, FIG. 4 is an exploded perspective view of a third embodiment of the invention, FIG. 5 is an exploded perspective view of a fourth embodiment of the invention, and FIG. 6 is a schematic diagram showing the circuit construction of a prior art. FIG. 1(A) is a schematic diagram of an internal circuitry provided in an electrical connection box. This internal circuitry has basically the same construction as the prior art shown in FIG. 6. In the prior art, the supply side circuitry upstream from the fuses F as indicated by bold lines in FIG. 6 is formed by the busbars, whereas the load side circuitry downstream from the fuses F as indicated by thin lines in FIG. 6 is formed by a combination of the wire and the cramping terminals. However, according to the invention, the internal circuitry is not divided by fuses F, but divided into a common circuitry 1 and a special circuitry 2. The common circuitry 1 is indicated by bold lines in FIG. 1(A) and the special circuitry 2 is indicated by thin lines in FIG. 1(A) More specifically, as shown in FIG. 1(B), out of circuits (1) to (10) connecting an input side to be connected with a power supply and an output side to be connected with respective wiring devices, the circuits (1), (5), (7), (9) and (10) are common circuits required for any of vehicles A, B and C as indicated by 0. For example, the circuit (1) is connected with a horn; the circuit (5) with headlights; the circuit (7) with back lights; the circuit (9) with a car radio; and the circuit (10) with taillights. All of the vehicles A, B and C are equipped with the horn, the headlights, the back lights, the car radio and the taillights. The remaining circuits (2), (3), (4), (6) and (8) are not common circuits, i.e., are not required by some of the vehicles A, B and C as indicated by x in FIG. 1(B). These circuits belong not to the common circuitry 1, but to the special circuitry 2. For example, they are connected with power windows, a door lock, a sun-roof, an air-bag, etc. As shown in FIG. 2, the common circuitry 1 is formed by flat busbars 10 formed by punching a conductive metal plate and bending specified parts of the punched metal plates to form tabs 10a. The flat busbars 10 are placed on the upper surface of an insulating plate 11, so that they can be horizontally arranged in the electrical connection box consisting of an upper casing 12 and a lower casing 13. In the electrical connection box assembled by putting the upper casing 12 and the lower casing 13 together and engaging respective locking portions 12a and 13b thereof, the special circuitry 2 is arranged at the lower level. Further, in the electrical connection box, the common circuitry 1, a conductive layer formed of the flat busbars 10, is arranged above the insulating plate 11. The tabs 10a of the flat busbars 10 project from terminal holes (not shown) formed in connector receptacles 12b formed on the outer (upper) surface of the upper casing 12, so that they can be connected with terminals of connectors to be fitted into the receptacles 12b. With the above electrical connection box, since the common circuitry 1 is used for all of the vehicles A to C, it is not necessary to form the flat busbars 10 of the common circuitry 1 in accordance with the type of the vehicle. The special circuitry 2 arranged at the lower level is formed by longitudinal busbars 20. As illustrated, the longitudinal busbars 20 are narrow rectangular conductive plates, and are disposed such that their surfaces extend in the vertical direction in the casing. External terminals (not shown) projecting inwardly from the terminal holes 13a of the lower casing 13 are directly engaged and connected with the lower edges of the longitudinal busbars 20. Since the common circuitry 1 is formed by the flat busbars 10 it can be commonly used for different vehicles. Further, since the special circuitry 2 is formed by the longitudinal busbars 20, the circuit construction can be changed only by changing the positions of the external terminals to be connected with the longitudinal busbars 20. FIG. 3 shows a second embodiment which is identical to the first embodiment in that the common circuitry 1 formed by the flat busbars 10 is arranged at the upper level in the electrical connection box, but differs therefrom in that the special circuitry 2 arranged at the lower level is formed by a combination of longitudinal busbars 20 and cramping terminals 21. The longitudinal busbars 20 are fitted in slots 21a of the cramping terminals 21 in their specified positions. External terminal connecting portions 21b at the other ends of the cramping terminals 21 are so mounted as to project downwardly from the terminal holes 13a of the lower casing 13, so that they can be connected with external terminals. As the other construction of the second embodiment is same as that of the first embodiment, description thereof is omitted by giving like reference numerals to like elements. Since the common circuitry 1 is formed by the flat busbars 10 in the second embodiment as well, it can be commonly used for different vehicles. Further, since the special circuitry 2 is formed by the longitudinal busbars 20 and the cramping terminals 21, the circuit construction can be changed only by changing the connecting positions of the longitudinal busbars 20 with the cramping terminals 21. In embodiments shown in FIGS. 4 and 5, the common circuitry 1 and the special circuitry 2 are formed by the same kind of conductive layers. In a third embodiment shown in FIG. 4, both the common circuitry 1 and the special circuitry 2 are formed by longitudinal busbars 20A and 20B, respectively. Connecting terminals mounted at the upper casing 12 and the lower casing 13 are directly connected with these longitudinal busbars 20A and 20B. The connection of the longitudinal busbars 20A and 20B is established, for example, by means of intermediate terminals (not shown) inserted into through holes formed in the insulating plate 11 mounted between them. In a fourth embodiment shown in FIG. 5, both the common circuitry 1 and the special circuitry 2 are formed by longitudinal busbars 20A, 20B and cramping terminals 21A, 21B, respectively. The connection of the longitudinal busbars 20A and 20B is established, for example, by means of intermediate terminals (not shown) inserted into through holes formed in the insulating plate 11 mounted between them. Since the common circuitry 1 and the special circuitry 2 are formed by the same kind of conductors in the third and fourth embodiments, the internal construction of the electrical connection box can be made simpler. Further, as the conductive layers can be formed in the same procedure, the electrical connection box can be more efficiently assembled.

Claims: An electrical connection box for a plurality of purposes, having an internal circuitry, wherein: the internal circuitry is divided into a common circuitry (1) common for all purposes and a special circuitry (2) which is not common for all purposes, and a conductive layer (10;20A) on which the common circuitry (1) is formed and another conductive layer (20;20B) on which the special circuitry (2) is formed are arranged one over the other at different levels in a casing (12,13) of the electrical connection box, characterized in that the conductive layer of the special circuitry (2) comprises longitudinal busbars (20;20B) extending in a vertical direction. An electrical connection box according to claim 1, wherein the conductive layer of the common circuitry (1) is formed by flat busbars (10). An electrical connection box according to claim 2, wherein the conductive layer of the common circuitry (1) comprises tabs (10a) which extend into connector receptacles (12b) so as to form terminals for the connection of the common circuitry (1) with external circuitry. An electrical connection box according to claim 2 or 3, wherein the flat bus-bars (10) comprise cramping terminals which extend to the conductive layer of the special circuitry (2) so as to be cramped thereto and establish connection therewith. An electrical connection box according to claim 1, wherein the common circuitry (1) and the special circuitry (2) comprises the same kind of conductive material, and wherein the conductive material comprises longitudinal busbars (20A,20B) arranged in a vertical direction An electrical connection box according to any of claims 2 to 5, wherein terminals for the connection of the special circuitry (2) with external circuitry are formed by cramping terminals (21;21B) cramped to the longitudinal bus-bars (20;20B). An electrical connection box according to claim 5 or 6, wherein connection between the conductive layers of the special and the common circuitries is made by intermediate terminals.

Inventors: ONIZUKA TAKAHIRO, SAKA YUUJI, ONIZUKA, TAKAHIRO, SAKA, YUUJI, ONIZUKA, TAKAHIRO, C/O SUMITOMO WIRING SYSTEMS LTD, Saka, Yuuji, c/o Sumitomo Wiring Systems, LTD
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1995
Main classification: B60R16
IPC codes: H05K3, H02G3, H01R9, H05K1, H01R4, B60R16