Electrical junction box for a vehicle

Details Electrical junction box for a vehicle Electrical junction box for a vehicle

2003-04-18

2004-01-13

Reichard, Dean A. (Department: 2831)

Electricity: conductors and insulators

Boxes and housings

C174S050510, C174S059000, C439S076200

Reexamination Certificate

active

06677521

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to an electrical junction box for a vehicle, in particular a box to be connected to a wire harness for a vehicle. The invention is intended to provide a junction box which is thin and compact even though the number of circuits is increased. The invention also provides a vehicle, such as an automobile, having the electrical junction box mounted on it.
2. Description of Related Art
Recently, the rapid increase in the number of electric and electronic component parts which are mounted on a vehicle has led to increase in the number of circuits to be accommodated in a junction box in the vehicle. When forming branch circuits at high density, it is necessary to mount a large number of component parts on the junction box, which increases the number of assembly stages.
The assignees of the present application proposed the junction box
1
shown in present
FIG. 21
in JP-A-2000-112691 (corresponding to EP-A-1145914 and U.S. patent application Ser. No. 09/833,595). The junction box of
FIG. 21
is intended to be thin, capable of permitting circuit alteration and reducing the time and labor required for its assembly from component parts.
In the junction box
1
of
FIG. 21
, a connector connection circuit (base circuit), a fuse connection circuit, and a relay connection circuit provided in the junction box are formed separately as a connector module
2
, a fuse module
3
and a relay module
4
. The connector module
2
, the fuse module
3
and the relay module
4
are incorporated in the casing composed of the lower case part
5
and the upper case part
6
.
In each of the connector module
2
, the fuse module
3
and the relay module
4
, bus bars
2
b
,
3
b
and
4
b
are fixed to insulation substrates
2
a
,
3
a
and
4
a
respectively, and project from the periphery of the insulation substrates to which they are attached.
Because the whole circuit of the junction box is divided into the connector module
2
, the fuse module
3
and the relay module
4
, overlap of the bus bar tabs can be avoided. Thus, the formation of multiple layers of bus bars can be prevented. Therefore, the junction box can be thin, and the circuits of the bus bars can be more easily wired. Thus, it is possible to reduce the area of the bus bar for each module. Consequently, even though the connector connection bus bars, the fuse connection bus bars and the relay connection bus bars are formed separately, the total area of all the bus bars can be reduced and the area of the junction box can be kept to a minimum.
Further, when the specification of any one of the connector circuit, the fuse circuit and the relay circuit is altered, it is only necessary to alter the respective module. Thus, the junction box permits alteration of the specification easily.
However, the bus bars used as electrical conductors in the modules are generally formed by punching metal sheet into a form corresponding to a complicated configuration of the circuit of the module. Thus, the yield of the metal sheet is low. Further, when a circuit alteration is made, it is necessary to make a new punching die, which can increase costs.
Further, depending on a circuit configuration, it may be impossible to form the circuit as a single layer. Thus the number of bus bar layers increase.
For example, as shown diagrammatically in
FIG. 22A
, in connecting circuits C
1
and C
2
to connectors
7
A and
7
B of a connector module
2
and to a fuse
8
of a fuse module
3
disposed on the side of the connector module, the circuits C
1
and C
2
of the connector module
2
cannot be connected to the fuse
8
unless the circuits C
1
and C
2
are disposed in separate layers. Thereby, the number of layers is increased.
Although the number of component parts mounted on a vehicle has increased rapidly, space for the junction box has remained limited. Thus, it is essential to make the junction box as thin as possible.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a junction box which is thin and can be manufactured at a low cost, in particular by improving the yield of a conductive metal plate.
It is a further object of the invention to simplify the wiring and conductor arrangements in a junction box and provide simplified methods of making the connector module of the junction box.
According to a first aspect of the invention, there is provided an electrical junction box having a casing and an electrical circuit in the casing adapted to make electrical connection, in use, to electrical connectors, fuses and relays. The electrical circuit comprises a fuse connection circuit, a relay connection circuit and a connector connection circuit, which is electrically connected to the fuse connection circuit and the relay connection circuit. The casing comprises a fuse circuit portion, containing the fuse connection circuit, and a relay circuit portion, containing the relay connection circuit. The casing also has two laterally opposite sides, each of which forms a connector accommodation portion adapted to receive, in use, at least one electrical connector.
Additionally, the electrical junction box may further have, mounted within the casing, a connector module providing the connector connection circuit that comprises a plurality of insulation substrates stacked one on another and each having a first main surface and a second main surface opposite the first main surface. A plurality of parallel elongate bus bars may be arranged on the first main surface of each substrate and extends in a first direction, and a plurality of parallel flexible conductors may be arranged on the second main surface of each insulation substrate and extends in a second direction orthogonal to the first direction. A plurality of apertures pass through each insulation substrate from the first main surface to the second main surface. The bus bars and the flexible conductors are connected to each other by welding to provide desired circuit connections at these apertures. The bus bars of each insulation substrate are oriented in the lateral direction of the casing between the opposite sides, some of which extend from the insulation substrates in the first direction and provide tabs that project into the connector accommodation portions.
The flexible conductors of each connector module may be single-core wires, or conductors of a flexible flat cable arranged on the second main surface of the insulation substrate, the flexible flat cable comprising flexible insulation material in which the conductors are held.
Thus in the connector module, the elongated bus bars and the flexible conductors cross each other, with the insulation substrate interposed between them, and are connected to each other at crossing positions to form the circuit of the connector module. Thus, it is possible to set the interval between the bus bars equal to the interval between the terminals of a connector to be attached to the box, in use. Thus, the tabs formed at both ends of the bus bars can project horizontally into the connector accommodation portion formed on the side surface of the box, with or even without bending the tabs.
In the circuit shown in
FIG. 22B
, in comparison with that of
FIG. 22A
, the conductors
21
can be connected to the fuses
35
while connecting both ends of the bus bars
22
, constituting circuits C
1
and C
2
, of the connector module
11
to connectors
7
A′ and
7
B′. Thus, it is possible to connect the bus bars
22
to the conductors
21
, disposed on the other side of the insulation substrate
20
, orthogonally to the bus bars
22
, with the insulation substrate
20
interposed between the bus bars
22
and the conductors
21
. Consequently, this simple circuit of the connector module
11
can be formed from a single circuit layer having the bus bar disposed on one surface of the insulation substrate and the conductors disposed on the other surface thereof. This simple example illustrates the principle of this aspect of the invention. That is, it is possible to reduce th

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