JP2001251728A - Circuit and junction box with housed circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of fuses to be mounted, by adding a fuse function to a circuit inside a junction box. SOLUTION: The width of a part of a conductive part 21, exposed on the surface of a board 20 composed of an insulating resin at the circuit 13 which is housed inside the junction box 10, is made thin, and a fuse circuit 25 is formed. The circuit 25 is imparted with fuse functions, in such a way that the width of a thin width 25a is blown, when a current larger than 1 ampere flows. A fuse, with an allowable current of 1 A to be mounted on the junction box 10, is dispersed with.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit body and a junction box containing the circuit body.
It is suitably used in a shunt box connected to an automobile wire harness.

[0002]

2. Description of the Related Art In recent years, with the rapid increase of electrical components mounted on automobiles, the number of electric junction boxes for automobiles, especially the circuits accommodated in junction boxes, has rapidly increased, and branch circuits are formed at high density. In addition, the number of parts has become very large, and the number of assembling steps has also increased significantly.

[0003] In a junction box 1 shown in FIG. 10 among the electric junction boxes for automobiles, bus bars 5A to 5D are stacked and arranged between upper case 2 and lower case 3 with insulating plates 4A to 4E interposed therebetween. Further, an insulating plate 15 provided with wire guide grooves at both upper and lower ends is disposed between the lower insulating plate 4A and the lower case 3, and wires 6A and 6B are laid on the insulating plate 15. The above busbars 5A to 5D
A tab 7 protrudes from the wire, and a press contact terminal (not shown) is press connected to the electric wires 6A and 6B.

On the upper surface of the upper case 2, there are provided a large number of fuse housings for mounting various fuses such as a fusible ring, a blade fuse, and a mini fuse. In addition, a relay housing for mounting the relay 8 and a connector are provided. A housing section is also provided. Further, a connector accommodating portion and the like are provided on the lower surface of the lower case 3.

[0005]

As described above, the internal circuit of the junction box is mainly of the bus bar type, but the electric wire and the press contact type in which a press contact terminal is connected to the electric wire may be used in some cases. In either case of the bus bar method and the pressure contact terminal method, the connection with the fuse is provided by a tab protruding from the bus bar, and a tab is provided on the pressure contact terminal press-connected to the electric wire, and these tabs are connected via the relay terminal. Connected to the fuse mounted in the fuse housing.

As described above, the connection between the internal circuit and the fuse requires a medium-diameter terminal, which causes a problem of increasing the number of parts of the junction box and the number of assembling steps. In particular, in the case of adopting a multi-layer laminate accompanying the recent increase in the density of internal circuits, the number of medium-diameter terminals used has further increased, and the above problem has become more serious.
Since the layout space of the relay terminal is required, the circuit design of the bus bar and the like is restricted, and the design becomes more difficult, which leads to a factor of increasing the size of the junction box.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and the number of fuses to be mounted in a junction box is reduced or the number of fuses is reduced to eliminate or reduce the number of relay terminals, thereby simplifying the structure of the junction box. The task is to reduce costs.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a circuit body housed in a junction box, wherein a circuit board made of an insulating resin is provided with a conductive body made of a highly conductive resin. The surface of the part is buried in an exposed state and integrally molded, the conductive part has a required circuit pattern, and a fuse circuit part having a narrow conductive part is provided in the circuit, The fuse circuit section is configured to be blown by a current larger than a set allowable current value.

That is, the present invention provides a new circuit body different from the bus bar, the electric wire and the press contact terminal, or the FPC used up to now as the internal circuit body housed in the junction box. As described above, the circuit body is buried and integrally molded with the surface of the conductive portion made of the highly conductive resin exposed on the substrate portion made of the insulating resin. It is molded into a circuit pattern.

As described above, since the conductive portion for forming the circuit pattern is formed by injection-molding a highly conductive resin, the conductive portion can be formed into an arbitrary shape. A fuse circuit portion having an area smaller than other portions can be easily provided.

As described above, when a fuse circuit is provided inside a circuit body and, for example, the function of a mini-fuse for about 1 amp is built in the circuit body, mounting of a mini-fuse corresponding to 1 amp in a junction box is required. Can be unnecessary. Along with this, there is no need to provide a conventional fuse housing portion on the outer surface of the junction box itself and a component portion including a medium-diameter terminal for connecting the mini-fuse to the internal circuit. The configuration can be simplified. When the allowable current amount of the conductive portion provided in the circuit body is increased, a function of a blade fuse of about 3 amps can be provided.

The conductive resin forming the circuit pattern is disclosed in JP-A-10-237331 and JP-A-11-342.
No. 522, in a thermoplastic resin,
It is made of a mixture of metal fibers made of copper, nickel, iron or the like, and a conductive resin composition in which a low-melting alloy such as lead-free solder (low-melting solder) and Cu powder is dispersed.

The thermoplastic resin to which conductive metal fibers are blended includes propylene, polyethylene, polystyrene, acrylonitrile / butadiene / styrene resin, modified polyphenylene oxide resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide resin, aromatic resin Polyamide resin, polyphenylene sulfide resin, liquid crystal polymer, polyetherimide,
Resins such as polybenzimidazole, polyetheretherketone, and polyethersulfone can be used alone or as a blend, and acrylonitrile-butadiene-styrene resin and polybutylene terephthalate resin are particularly preferably used.

As the low melting point alloy to be mixed and dispersed in the thermoplastic resin and to be joined in a network, an alloy having a melting point of 100 ° C. or higher, preferably 200 ° C. or higher and melting at the time of injection molding is used. System, Sn-Ag
-Pb system, Sn-Bi system, Sn-Bi-In system, Bi-
Pb-based, Bi-Sn-based, Sn-Cu-based, Sn-Cu-N
i-P system, Sn-Ag system, Sn-Bi-Pb system, Sn-
In-based materials may be mentioned.

In the circuit body using the highly conductive resin as a conductive portion, a first injection molding (first color) using a mold is performed with an insulating resin to form a substrate portion. A second injection molding (second color) is performed with a highly conductive resin in a mold to form a conductive portion, and in two steps, a circuit body in which the substrate portion and the conductive portion are integrated into a flat plate shape is formed.

It is preferable that the circuit body has a substantially flat plate shape, and at least one of the two surfaces is an insulating surface composed of only an insulating resin layer.

As described above, when one surface of the circuit is an insulating surface, when the circuit is housed in a stacked state inside the junction box, there is no need to interpose an insulating plate between these circuits, What is necessary is just to laminate | stack so that the surface where the conductive part of one circuit body exposed to the surface and the insulating surface of another circuit body may contact | abut. Therefore, since the insulating plate is not required, the number of parts and the number of assembling steps can be reduced, and the size of the junction box can be reduced.

The present invention provides a junction box connected to an automobile wire harness containing the above-mentioned circuit body. Although the above-mentioned circuit body alone may be used as the internal circuit of the junction box, an internal circuit consisting of a bus bar is laminated and arranged together with the circuit body, and the bus bar is a large current circuit, while the circuit body is a medium / small current circuit. It may be a circuit.

As described above, when the circuit body is a medium / small current circuit and a fuse circuit is provided in the circuit, a large number of fuses to be attached to the junction box can be eliminated.

[0020]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view of a junction box 10 connected to an automobile wire harness.
1 is an upper case, 12 is a lower case, and 13 (13
A and 13B) are circuit bodies, 14 is a bus bar, 15 is a single core wire for press contact, 16 is a press contact terminal, and 17 is a conductive pin. The bus bar 14 is used as a large current circuit connected to a power supply, the single core wire 15 is used as a medium current circuit, and the circuit body 13 is used as a small current circuit. An insulating plate (see FIG. (Not shown). Although a connector housing, a relay housing, and the like are provided on the upper surface of the upper case 11 and the lower surface of the lower case 12, a fuse housing for mounting a mini fuse is not provided.

Upper circuit body 13A in circuit body 13
As shown in FIGS. 2A and 2B, a conductive portion 21 (shown by oblique lines in the figure) made of a highly conductive resin was exposed in a strip shape on a substrate portion 20 made of an insulating resin. It is buried in a state, and is integrally formed so as to have a flat plate shape as a whole. The surface 21a of the conductive portion 21 is formed on the same surface as the upper surface 20a of the substrate portion 20, and has a circuit shape matching a required circuit pattern. The lower surface 20b of the substrate part 20 exposes the lower exposed part 21b of the conductive part 21 flush, and the other part is an insulating surface.

The lower circuit body 13B is substantially the same as the upper circuit body 13A, but does not have a lower exposed portion in the conductive portion, and the entire lower surface is an insulating surface made of only an insulating resin layer. . When the circuit body 13A and the circuit body 13B are stacked, conduction of the upper and lower conductive parts is achieved via the lower exposed part 21b, thereby simplifying the connection, and the lower circuit body 13B.
Since the lower surface side of B is an insulating surface, an insulating plate is not required on the lower surface side of the circuit body 13B.

As shown in FIGS. 2A and 3A, a large number of fuse circuit portions 25 are formed in a part of the conductive portion 21 by reducing the width of the flat plate shape. Fuse circuit section 25
Is for 1 amp, which is the allowable current value of a conventional minifuse. Therefore, the width dimension W and the length dimension L of the narrow section 25a of the fuse circuit section 25 are such that when a current larger than 1 amperes flows, the narrow section 25a is blown as shown in FIG. Is set to That is, since the cross-sectional area of the fuse circuit portion 25 is smaller than the cross-sectional area of other portions of the conductive portion 21, the resistance value of the fuse circuit portion 25 is larger than that of the conductive portion 21 having a normal width. I have. Therefore, when a current having a value larger than the specified current value flows, the narrow portion 25 itself of the fuse circuit portion 25 is blown by resistance heating due to an overcurrent, and exhibits a fuse function.

Conductor 2 having fuse circuit section 25
In the method of manufacturing the circuit body 13 including the first and second portions, in forming the substrate portion 20, the convex portion 30b having the same shape as the conductive portion 21 and the narrow convex portion 30c having the same shape as the fuse circuit portion shown in FIG. An upper mold 30 having a large concave portion 30a for forming the substrate 20 and a lower mold 31 having a flat upper surface are used. As shown in FIG. 5A, a cavity is formed by the concave portion 30a by clamping the upper and lower molds 30 and 31, and an insulating resin is injected into the cavity to inject a primary molded product consisting of only the substrate portion 20. Molding. In this state, the conductive part 21 is not provided on the substrate part 20.

Next, the upper mold 30 is changed to another upper mold 33 having only the concave portion 33a corresponding to the substrate section 20 shown in FIG. 4B, and as shown in FIG. 5B. The upper mold 33 and the lower mold 31 similar to the above are clamped, and the substrate 20
A cavity 32 is formed between the upper and lower molds 33 and 31. Thereafter, as shown in FIG.
The conductive portion 21 is injection-molded by injecting a highly conductive resin. Thereby, the circuit body 13 including the conductive portion 21 having the required circuit shape and the fuse circuit portion 25 on the surface of the substrate portion 20 is integrally formed. After the conductive portion 21 is molded as a primary molded product, the substrate portion 20 is secondary molded to form the circuit body 1.
3 may be molded.

When the circuit body 13 formed as described above is used as a small current circuit in the internal circuit of the junction box 10, the fuse circuit portion 25 of the conductor 21 is replaced with a mini-fuse for one amp mounted in a conventional junction box. Of the junction box 1
0 eliminates the need for a 1 amp minifuse. Therefore, it is not necessary to provide a fuse accommodating portion for mounting a mini-fuse on the surfaces of the upper case 11 and the lower case 12, and a relay terminal for connecting a mini-fuse is not required, and the junction box 10 has a simpler structure than the conventional case. I have.

The fuse circuit 2 of the conductor 21
The allowable current value of 5 is not limited to 1 amp,
The size of the narrow width portion 25a of the fuse circuit portion 25 may be appropriately increased or decreased so as to correspond to various allowable current values to which the minifuse can be applied. Further, the allowable current value of the conductive portion provided in the circuit body is increased, and in the junction box 10 shown in FIG. 1, the circuit body is also used in the middle current circuit using the single core wire 15 and the fuse circuit portion is provided in the conductive portion. To provide a blade fuse function of about 3 amps,
The number of mounted fuses may be further reduced.
Note that the number of stacked circuit bodies can be appropriately increased or decreased without being limited to the number of stacked layers in the present embodiment.

FIG. 6A shows a modified circuit body 43 including a conductor having a fuse circuit portion. Circuit body 4
3, the fuse circuit portion 55 is formed on the conductor 51 of the substrate portion 50 in the same manner as described above, but the substrate portion 5 is formed in a recessed portion of the conductor 51 on both sides of the narrow portion 55a of the fuse circuit portion 55.
Space 57-1, 5
7-2. When the spaces 57-1 and 57-2 are provided on both sides of the narrow portion 55a in this manner, when an overcurrent flows and the narrow portion 55a is blown, as shown in FIG. Since the pieces 55a-1 and 55a-2 can escape in the direction in which they are separated from each other, the blown narrow piece 5
The possibility that 5-1 and 2 come into contact with each other again can be eliminated, and the conduction can be reliably stopped.

The fuse circuit portion 55 including the spaces 57-1 and 57-2 is formed without providing a portion for forming the fuse circuit portion of the upper mold for forming the substrate portion in the above-described manufacturing method.
As shown in (A), the upper mold 30 'is provided with only the protrusion 30b' corresponding to the conductive portion. Further, the upper mold 33 ′ for forming the conductive portion is provided with the narrow width portion 55 of the fuse circuit portion 55.
a to form protrusions 33b 'at positions corresponding to both sides,
The spaces 57-1 and 57-2 are formed.

Further, the narrow portion is not limited to the linear shape,
As shown in FIG. 8, the mini-fuse is formed in a bent shape in the same manner as the fusing portion, and spaces 57-1 'and 2' are provided on both sides of the narrow width portion 55a ', so that conduction is further ensured at the time of fusing. You may make it stop. Further, in the case of responding to a minute current, or in the case where the thickness of the conductive portion is large and the width of the conductive portion is not enough to cope with the allowable current value, FIG.
(A) As shown in (B), the width of the conductor 51 ″ is reduced in the fuse circuit portion 55 ″, and the conductor 51 ″ is reduced.
The upper and lower surfaces may also be depressed to form narrow portions 55a ″.

[0031]

As is apparent from the above description, the number of fuses mounted on the junction box can be reduced by using the circuit body having the fuse circuit portion of the present invention.
Accordingly, the number of relay terminals can be reduced accordingly, and the connection between the laminations can be made by surface contact of the conductor, and the number of interposed insulating plates can be reduced by the insulating surface of the circuit body. The time can be reduced, and the cost of the junction box can be reduced.

Further, the reduction in the number of relay terminals increases the degree of freedom in circuit design, enables the density of the same layer to be further increased, and contributes to the promotion of a small and lightweight junction box. Furthermore, there is no need to provide a fuse accommodating section on the upper case and lower case surfaces, and the mold shape for molding the upper and lower cases can be made simpler than before.
Mold manufacturing costs can also be reduced.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a junction box according to an embodiment of the present invention.

FIGS. 2A and 2B show a circuit body, where FIG. 2A is a perspective view and FIG. 2B is a cross-sectional view along AA in FIG.

FIG. 3A is a plan view of a fuse circuit unit, and FIG. 3B is a plan view of the fuse circuit unit in a blown state.

FIG. 4A is a perspective view of an upper mold used for molding a substrate portion, and FIG. 4B is a perspective view of an upper mold used for molding a conductive portion.

FIGS. 5A, 5B, and 5C are schematic diagrams showing a molded state of a circuit body.

FIG. 6A is a perspective view of a fuse circuit unit according to a modification;
(B) is a plan view of the fuse circuit portion in a blown state.

FIG. 7A is a perspective view of an upper mold for molding a substrate portion of a modification, and FIG. 7B is a perspective view of a conductive portion molding of a modification.

FIG. 8 is a plan view of a fuse circuit section of another modification.

9A is a plan view of a fuse circuit section according to another modification, and FIG. 9B is a cross-sectional view taken along line BB in FIG. 9A.

FIG. 10 is an exploded perspective view of a conventional junction box.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Junction box 11 Upper case 12 Lower case 13 (13A, 13B) Circuit body 14 Bus bar 15 Single core wire 17 Conducting pin 20 Board part 21 Conductive part 25 Fuse circuit part 25a Narrow width part

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor: Yuki Saito, 1-114, Nishisuehirocho, Yokkaichi, Mie Prefecture Inside Sumitomo Wiring Systems, Ltd. (72) Inventor: Nobufumi Kobayashi, 1-14, Nishisuehirocho, Yokkaichi, Mie Prefecture No. Sumitomo Wiring Systems, Inc. F-term (reference) 5G361 BA04 BB03 5G502 AA01 BB07 BB13

Claims (3)

[Claims] 1. A circuit body housed in a junction box, wherein the circuit body is buried in a substrate portion made of an insulating resin in a state where a surface of a conductive portion made of a highly conductive resin is exposed and integrally molded. The conductive portion has a required circuit pattern, and a fuse circuit portion having a narrow conductive portion is provided in the circuit, and the fuse circuit portion is blown by a current larger than a set allowable current value. A circuit body characterized in that: 2. The circuit body according to claim 1, wherein the circuit body has a flat plate shape, and at least one of the two surfaces is an insulating surface made of only an insulating resin layer. 3. A junction box connected to a wire harness for an automobile, which houses the circuit body according to claim 1.