An electrical connection box

Abstract: To make an electrical connection box smaller, lighter and more highly functional by improving internal circuits thereof. A printed circuit board 23 having electronic devices mounted thereon and a busbar 24 are provided as internal circuits to be accommodated in a casing of an electrical connection box. Terminals 24a provided in the busbar 24 are inserted through the printed circuit board 23 to be secured to a conductive portion by solders 30 for a direct electrical connection.

Description: The present invention relates to an electrical connection box such as a junction box used for an automotive vehicle and is designed to make the electrical connection box smaller and lighter and to reduce the number of parts by making internal circuits accommodated in the electrical connection box highly functional. Conventionally, internal circuits of an electrical connection box such as a junction box are formed by busbars formed e.g. by punching a conductive metal sheet and, in many cases, being placed one over another with insulating plates held therebetween. If the internal circuits are formed by the busbars as described above, the busbars need to be newly worked in the case of a circuit change, which leads to an increase in production costs. In view of this, some internal circuits of load side circuits downstream from a fuse where conventionally a circuit change is relatively frequently necessitated are formed by wires (single-core wires) and cramping terminals to be pressingly connected with the wires. Further, a printed circuit board having electronic devices such as relays, diodes and capacitors mounted thereon may be provided in the electrical connection box. A known highly functional electrical connection box is, as shown in FIG. 5, such that a laminated portion 5 where busbars 3 and insulating plates 4 are laminated and a printed circuit board 6 are accommodated in different levels in a casing comprised of an upper casing 1 and a lower casing 2. The busbars 3 and the printed circuit board 6 are connected via connectors 7 as intermediate parts. Each connector housing 7a for connecting the circuit board is mounted on an outer edge of the printed circuit board 6, and male terminals 3a in the form of tabs formed by bending the busbars 3 are inserted into the respective terminal chambers of the connector housing 7a to be connected with female terminals 7b set in the connector housing 7a. The female terminals 7b and a conductive portion of the printed circuit board 6 are connected as follows. Ends of a circuit portion arranged on the rear surface of the insulating board 6a of the printed circuit board 6 are extended to the outer edges of the printed circuit board 6. A copper leaf or area is exposed only at leading ends 8 of the circuit portion which are aligned. An electrical connection is established by holding the leading ends 8 of the circuit portion by the female terminals 7b. In an electrical connection box shown in FIG. 6 and FIG. 7, a busbar 3, a printed circuit board 6 and an internal circuit formed by single-core wires 9 and cramping terminals 10 are accommodated in different levels in a casing comprised of an upper casing 1 and a lower casing 2. In this electrical connection box, hollow box-shaped female intermediate terminals 11 are provided on the printed circuit board 6, and a pair of leg portions 11a projecting from the bottom ends of the intermediate terminals 11 are inserted through holes 6b formed in the insulating board 6a of the printed circuit board 6 and mounted at the lower surface side of the insulating plate 6a to be connected with a conductive portion via solders 12 as shown in FIGS. 7(A) and 7(B). Tab-shaped male terminals 3a projecting from the busbars 3 and tab-shaped male terminals 10a of the cramping terminal 10 connected with the single-core wires 9 are inserted into the intermediate terminals 11 to be electrically connected. In the electrical connection box shown in FIG. 5, since the busbar terminals 3a and the conductive portion of the printed circuit board 6 are connected via the connectors 7 as the intermediate parts, the number of parts and the number of assembling steps are increased, thereby increasing costs for parts, assembling and maintenance and accordingly production costs. Likewise, since the cramping terminals 10 connected with the single-core wires 9 and the busbar terminals 3a are connected with the conductive portion of the printed circuit board 6 via the intermediate terminals 11 in the electrical connection box shown in FIGS. 6 and 7, the number of parts and the number of assembling steps are increased, thereby increasing costs for parts, assembling and maintenance and accordingly production costs. Further, the use of the connectors 7 and the intermediate terminals 11 as the intermediate parts necessitates a space for providing them and makes the electrical connection box larger and heavier. Therefore, it is difficult to compact the electrical connection box by a high density arrangement. WO 94/29145 A relates to an electrical connection box in which a printed circuit board having electric devices and at least one busbar are accommodated in substantially different levels in a casing. A plurality of terminals are projecting from the busbar. The printed circuit board has a plurality of female terminals so that to it for receiving therein a male blade of the busbar. Assembling this connector requires a first step of placing terminals at the printed circuit board, soldering these to the circuit board and inserting the male blades into the terminals. This assembly process is laborious, and the resulting connector is rather bulky, since a considerable space for the connectors is required between the printed circuit board and the busbar. The object of the present invention is to provide an electrical connection box having an improved space efficiency and a reduced number of mounting steps. This object is fulfilled by a connection box having the features disclosed in claim 1. Preferred embodiments are defined in the dependent subclaims. According to the invention, there is provided an electrical connection box in which at least one printed circuit board having electric and/or electronic devices mounted thereon and at least one busbar are accommodated in substantially different levels in a casing, wherein one or more terminals projecting from the busbar are soldered and/or bonded to a corresponding conductive portion of the printed circuit board for a direct electrical connection. Such an electrical connection box improves a connection mode of a printed circuit board with busbars and cramping terminals to be accommodated in an electrical connection box, thereby making it unnecessary to use connectors, intermediate terminals and like intermediate parts, which are required in the prior art, to reduce the number of parts and the number of assembling steps, so that production costs can be reduced and the electrical connection box can be made more highly functional, smaller and lighter. If the terminals projecting from the busbar are directly soldered or bonded (e.g. by ultrasonic waves or heat) to the conductive portion of the printed circuit board as described above, connectors, intermediate terminals or like intermediate parts which are required in the prior art can be dispensed with. According to a preferred embodiment of the invention, an insulating plate is at least partially provided between the printed circuit board and the busbar; one or more insulating plate through holes are formed in the insulating plate; and the terminals projecting from the busbar are inserted or insertable through the insulating plate through holes. Accordingly, the circuit board and/or the busbar can be formed with non-insulated circuit paths, since a danger of short circuits of one element by the other is prevented by the insulating plate disposed therebetween. Preferably, one or more board through holes are formed in the printed circuit board; and the terminals projecting from the busbar are inserted or insertable through the board through holes. Further preferably, portions of the terminals projecting from the board through holes of the printed circuit board are soldered and/or bonded to be connected with the conductive portion of the printed circuit board. Most preferably, portions of the terminals projecting from the board through holes of the printed circuit board project into one or more connector receptacles formed in the casing so as to be connected to a mating connector. Specifically, an insulating plate is provided between the printed circuit board and the busbar; through holes are formed in the insulating plate and the printed circuit board; the terminals projecting from the busbar are inserted through the through holes; and portions of the terminals projecting from the through holes of the printed circuit board are soldered to be connected with the conductive portion of the printed circuit board. According to a further preferred embodiment, an internal circuit comprising one or more wires and cramping terminals being connected or connectable with the wires at a first end is further accommodated in a substantially different level in the casing, and a second end of each cramping terminal is soldered and/or bonded to the conductive portion of the printed circuit board for a direct electrical connection. In the case that an internal circuit comprising wires and cramping terminals connected with the wires is further accommodated in a different level in the casing, the other end of each cramping terminal having one end thereof connected with the wire is soldered to the conductive portion of the printed circuit board for a direct electrical connection. By directly connecting the cramping terminals connected with the wires with the printed circuit board, the use of intermediate parts is not necessary. This reduces the number of parts and the number of assembling steps and makes a space for the intermediate parts unnecessary. As a result, the electrical connection box can be made smaller and lighter. Preferably, one or more auxiliary cramping terminals being connected or connectable to the wires project into one or more connector receptacles being provided on the casing for the connection with a mating connector. Most preferably, an internal circuit insulating plate is arranged substantially between the busbar and the internal circuit, the internal circuit insulating plate having terminal holes for the insertion of the cramping terminals therethrough. 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. 1 is an exploded perspective view of an electrical connection box according to one embodiment of the invention, FIG. 2 is a section of the electrical connection box in its assembled state, FIG. 3 is an enlarged exploded view of an essential portion, FIG. 4 is a section showing a state where a busbar and a cramping terminal are connected with a printed circuit board, FIG. 5 is an exploded perspective view of a prior art electrical connection box, FIG. 6 is an exploded perspective view of another prior art electrical connection box, and FIG. 7(A) is an exploded perspective view of an essential portion of FIG. 6 and FIG. 7(B) is a section of the essential portion in its assembled state. Hereafter, one embodiment of the invention is described with reference to FIGS. 1 to 4. Three kinds of internal circuits: a printed circuit board 23 having electric and/or electronic devices 22 mounted thereon, at least one busbar 24, a combination of single-core wires 25 and cramping terminals 26, are accommodated in a casing comprised of lower and upper casings 20, 21 of an electrical connection box with insulating plates 27, 28 provided therebetween. Specifically, the single-core wires 25 are arranged on or at the upper surface of the lower casing 20, and bottom blade portions 26a of the cramping terminals 26 are connected or connectable with the single-core wires 25. The insulating plate 28 for the single-core wires 25 is arranged above or at the single core-wires 25, and the busbar 24 is arranged on or at the upper surface of the insulating plate 28. The insulating plate 27 is arranged above the busbar 24 and the printed circuit board 23 is arranged above or at the insulating plate 27. The upper casing 21 is placed above the printed circuit board 23 to substantially close the electrical connection box. The printed circuit board 23 has its opposite ends placed on preferably step-shaped locking portions 21a formed on the inner surfaces of the side walls of the upper casing 21 so as to substantially horizontally extend (or extend in a direction substantially parallel to the plane of the circuit board 23 or an arrangement plane) inside the electrical connection box. Conductive portions 23b, 23c are printed on the upper and lower surfaces of an insulating board 23a of the printed circuit board 23, and electronic devices 22 mounted on the lower surface (FIG. 2) and/or upper surface (FIG. 1) are connected with the conductive portion 23c on the lower/upper surface. Further, through holes are formed as terminal holes 23d, 23e in specified (predetermined or predeterminable) positions of the insulating board 23a and the conductive portion 23b of the printed circuit board 23. Through holes are also formed as terminal holes 27a in specified (predetermined or predeterminable) positions of the insulating plate 27 provided between the printed circuit board 23 and the busbar 24, and as terminal holes 28a in specified (predetermined or predeterminable) positions of the insulating plate 28 provided between the busbar 24 and the single-core wires 25. In specified positions of the busbar 24 are male terminals 24b in the form of upright tabs which are formed by bending horizontal portions (or portions substantially parallel to the arrangement plane) 24a. The male terminals 24b are inserted or insertable through the terminal holes 23d of the printed circuit board 23 after being inserted through the terminal holes 27a of the insulating plate 27. Leading ends 24b-1 of the male terminals 24b projecting from the upper surface of the printed circuit board 23 are directly electrically connected with the conductive portion 23b on the upper surface of the printed circuit board 23 by solders 30. Alternatively or additionally the leading ends 24b-1 of the male terminals 24 may be bonded to the corresponding conductive portions 23b of the printed circuit board 23 e.g. by ultrasonic and/or heat bonding. The leading end 24b-1 may be tapered or thinned or slanted so as to be more easily inserted or insertable into or positioned with respect to the terminal holes (23d, 23e, 27a and/or 28a). Further, preferably upward projecting tab-shaped male terminals 26b of the cramping terminal 26 connected with the single-core wires 25 are inserted or insertable through the terminal holes 28a of the insulating plate 28 and the terminal holes 27a of the insulating plate 27 and further through the terminal holes 23d of the printed circuit board 23. Portions of the male terminals 26b projecting from the upper surface of the printed circuit board 23 are or may be directly connected with the conductive portion 23b on the e.g. upper surface of the printed circuit board 23 preferably by solders 31. Cramping terminals 29 having preferably downward projecting tabs are connected or connectable with the single-core wires 25. These tabs are caused to project from terminal holes 35a formed in connector receptacles 35 provided on the lower casing 20 for the connection with external connectors (not shown). Further, connector receptacles 36 are provided on the upper casing 21 to connect external connectors (not shown) and the internal circuits inside the casing via terminals 37, connected with printed circuit board 23 e.g. by soldering. Further, relay and/or fuse (or other electric or electronic device) mount portions 38 are provided to connect relays and fuses or other electric or electronic device (not shown) with the internal circuits. In the electrical connection box thus constructed, the busbar 24 and the printed circuit board 23, the cramping terminals 26 and the printed circuit board 23 accommodated in the casing comprised of the lower and upper casings 20, 21 can be directly electrically connected without using intermediate parts such as connectors and intermediate terminals. The terminal holes 23d, 23e, 27a and/or 28a are provided in such positions so as to substantially correspond to or mate with parts or portions of the busbar 24 and/or cramping terminals 29, which are thus arrangeable therethrough. As is clear from the above description, in the electrical connection box according to the invention, the printed circuit board having electronic devices mounted thereon is directly electrically connected or connectable with the busbar and the cramping terminals as other internal circuits of the electrical connection box without using any intermediate parts. Accordingly, the number of parts and the number of assembling steps can be reduced, with the result that production costs can considerably be reduced. Further, since the internal circuits: the printed circuit board, the busbar, the single-core wires and the cramping terminals are combined and arranged in different levels, they can be efficiently accommodated in the electrical connection box. Since the intermediate parts for connecting the internal circuits are not necessary, the electrical connection box can be made smaller and lighter by eliminating a space for the intermediate parts. Furthermore, since a plurality of kinds of internal circuits are used, internal circuits corresponding to amounts of power applied can selectively be used and it is easy to respond to a circuit change. LIST OF REFERENCE NUMERALS 20 Lower Casing 21 Upper Casing 22 Electronic Device 23 Printed Circuit Board 24 Busbar 25 Single-Core Wire 26 Cramping Terminal 27, Insulating Plate 30, 31 Solder

Claims: An electrical connection box in which at least one printed circuit board (23) having electric and or electronic devices (22) mounted thereon and at least one busbar (24) are accommodated in substantially different level in a casing (20; 21), the busbar (24) comprising one or more terminals (24b) projecting therefrom, characterized in that one or more terminals (24b) are soldered and/or bonded to a corresponding conductive portion (23b, 23c) of the printed circuit board (23) for a direct electrical connection. An electrical connection box according to claim 1, wherein an insulating plate (27) is at least partially provided between the printed circuit board (23) and the busbar (24); one or more insulating plate through holes (27a) are formed in the insulating plate (27); and the terminals (24b) projecting from the busbar (24) are inserted or insertable through the insulating plate through holes (27a). An electrical connection box according to one or more of the preceding claims, wherein one or more board through holes (23d; 23e) are formed in the printed circuit board (23); and the terminals (24b) projecting from the busbar (24) are inserted or insertable through the board through holes (23d; 23e). An electrical connection box according to claim 3, wherein portions (24b-1) of the terminals (24b) projecting from the board through holes (23d; 23e) of the printed circuit board (23) are soldered and/or bonded to be connected with the conductive portion (23b; 23c) of the printed circuit board (23). An electrical connection box according to claim 3 or 4, wherein portions (24b-1) of the terminals (24b) projecting from the board through holes (23d; 23e) of the printed circuit board (23) project into one or more connector receptacles formed in the casing (20; 21) so as to be connected to a mating connector. An electrical connection box according to one or more of the preceding claims, wherein an internal circuit comprising one or more wires (25) and cramping terminals (26) being connected or connectable with the wires (25) at a first end (26a) is further accommodated in a substantially different level in the casing (20; 21), and a second end (26b) of each cramping terminal (26) is soldered and/or bonded to the conductive portion (23b; 23c) of the printed circuit board (23) for a direct electrical connection. A connector according to claim 6, wherein one or more auxiliary cramping terminals (29) being connected or connectable to the wires (25) project into one or more connector receptacles (35) being provided on the casing (20; 21) for the connection with a mating connector. A connector according to claim 6 or 7, wherein an internal circuit insulating plate (28) is arranged substantially between the busbar (24) and the internal circuit, the internal circuit insulating plate (28) having terminal holes (28a) for the insertion of the cramping terminals (26; 29) therethrough.

Inventors: KASAI KOJI, KASAI, KOJI
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1999
Main classification: H01R9
IPC codes: H01R31, H05K1, H01R9, H01R12, H05K3, H02G3