JP2002058137A - Junction box and assembling method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To thin a junction box by reducing the number of layers of bus bars in the junction box. SOLUTION: This junction box 10 is mounted separately with a connector module 13, a fuse module 14 and/or a relay module 15 stored in an upper case 12 and a lower case 11. The respective modules include vertical tabs 16c, 20a and is provided with a protruding part P at least on one side of the mating surface thereof. The respective modules are arranged overlaid in the horizontal direction, and the respective tabs thereof are jointed in overlaid the vertical direction. Welding is performed with the positions regulated, while the respective tabs are abutted against the protruding part P which is crushed by guiding bosses 51 provided on one module into long boss holes 52 provided in the other module.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a junction box to be connected to a wire harness for an automobile and a method of assembling the junction box. More particularly, the present invention is intended to reduce the thickness and size of the junction box even if the number of circuits increases.

[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 is very large, and the number of assembling steps is very large.

In a junction box 1 shown in FIG. 9 among electric connection 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. Upper case 2
Is provided with a connector accommodating portion 2a, a relay accommodating portion 2b, and a fuse accommodating portion 2c. A connector 6, a relay 7, and a fuse 8 are mounted in these accommodating portions, and these terminals and tabs protruding from the bus bar are directly or indirectly connected. They are connected via relay terminals. The lower case 3 is also provided with a connector accommodating portion 3a, and the tab 5a of the bus bar projects to connect to the connector.

[0004]

In the junction box 1, there is a problem that the area of the bus bar and the number of laminations increase as the number of circuits increases, and the junction box becomes large. When a connector housing, a relay housing, and a fuse housing are provided in both the upper case and the lower case, and the connector, relay, fuse and the internal circuit are connected to the upper and lower surfaces of the junction box, the upper case or It is possible to suppress an increase in the area of the junction box as compared with a case where the junction box is provided only on one side of the lower case.

However, if the connector accommodating portion and the relay accommodating portion or the fuse accommodating portion are provided at the vertically opposed positions, the tabs bent by the bus bar overlap and cannot be developed. Therefore, it is necessary to provide the tab on the bus bar of another layer. This causes the number of layers to increase. As described above, when the number of layers of the bus bar increases, there is a problem that the height of the junction box increases and the size of the junction box increases.

Further, since the connector, the fuse, and the relay are connected to the bus bar in the junction box, if the specification changes to change the connection between the fuse, the relay and the internal circuit, the entire internal circuit is changed. Therefore, there is a problem that the circuit cannot be easily changed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a circuit in a junction box is accommodated in a junction box by modularizing a connector connection circuit section, a fuse connection circuit section, and a relay connection circuit section. It is an object of the present invention to suppress an increase in the number of busbar layers, to reduce the thickness of a junction box, and to easily respond to circuit changes. In addition, when the modules are modularized as described above, the welding workability is improved so that the bus bars of each module are connected by welding, and the workability of assembling these modules to the upper case and the lower case is improved. Is also an issue.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention divides a connector connection circuit section, a fuse connection circuit section and / or a relay connection circuit section accommodated in an upper case and a lower case of a junction box. And a fuse module and / or a relay module are separately provided as a connector module, a fuse module and / or a relay module, and the fuse module and / or the relay module are horizontally arranged on the connector module, and each of the modules has a bus bar fixed to an insulating plate. In addition, these bus bars have tabs bent in the vertical direction, the tabs of the module are overlapped with each other, and a projection projecting toward the other side is provided on the mating surface of one of the tabs, and the projection is welded. Sometimes crushed and welded, it is placed on top of A boss protrudes vertically to one of the connector module and the fuse module and / or the insulating plate of the relay module, and the other boss is positioned on one of the insulating plates so that the boss can be fitted when the tabs are welded to each other. A boss hole is provided, and the boss hole is formed from a long hole extending in a direction that allows the tab to move to a joining position where the mating surface of the tabs abuts from the standby position where the tabs are separated from each other by the projection. We provide a junction box characterized by becoming.

As described above, in the junction box of the present invention, the connector connection circuit for connecting to an external electric wire via the connector, the fuse connection circuit and the relay connection circuit are divided into connector modules, fuse modules and relay modules. Are provided separately. That is, the bus bar for the base circuit for connecting the connector, the bus bar for the fuse, and the bus bar for the relay are provided separately.

Conventionally, one conductive plate is punched out to provide a connector connection circuit, a fuse connection circuit, and a relay connection circuit, and each of the circuits has a connector connection tab, a fuse connection tab, and a relay connection tab. This arrangement complicates the circuit layout, resulting in an increase in the area of the bus bar and an increase in the number of bus bars.
On the other hand, in the present invention, the bus bar for connector connection,
The bus bar for fuse connection and the bus bar for relay connection are divided and punched from separate conductive plates, and since they are arranged at different positions, the tabs do not overlap, so that the multilayering of the bus bar is suppressed, The junction box can be made thinner. In addition, since the circuit layout of each bus bar is also simplified, the area of each bus bar can be reduced.As a result, even if the bus bar is divided, the overall bus bar area can be reduced, and the increase in the junction box area can be suppressed. it can.

Further, since the connector module, the fuse module, and the relay module are provided separately, if any of the connector circuit, the fuse circuit, and the relay circuit is changed in specifications, the changed connector module, fuse module, It is only necessary to change the relay module, and it is possible to easily cope with the specification change.
As described above, the bus bar for connecting the connector and the bus bar for connecting the fuse and / or the relay are divided but welded, so that the reliability of the electrical connection does not decrease. The tabs are specifically joined together and connected by ultrasonic welding, resistance welding or laser welding. Since at least one of the mating surfaces of the tabs to be overlapped among the tabs is provided with a projection protruding toward the other side, a reliable welding surface can be obtained by crushing the projection as a welding point. .

When the fuse module and / or the relay module are horizontally overlapped with the connector module, a boss projecting vertically from one of the insulating plates is provided on one of the other. The tabs are overlapped on a vertical plane via the projections by fitting and positioning in the boss holes formed of holes, so that the tabs can be accurately positioned and the projections are It can be used as a welding point to perform reliable welding. Furthermore, when welding the tabs while compressing the tabs, the modules arranged one on top of the other are relatively moved due to the collapse of the projections. As a result, stress is not applied to the welded tabs, and the tabs can be reliably welded and connected.

When arranging the module welded by the tab in the lower case, a positioning pin projecting from the lower case is inserted into a positioning hole provided at a corresponding position between the insulating plates of the module. Assembly,
Thereafter, since the upper case is fitted to the lower case, the module after welding can be reliably positioned and held in the lower case. Also, if the welding between the tabs is incomplete and misaligned,
Since the positioning pin is not inserted into the positioning hole, the position shift state can be easily found.

Although the fuse module and the relay module may be provided separately, they may be integrated to form a combined fuse / relay module. In this case, a bus bar for a fuse and a bus bar for a relay are fixed on a common insulating plate. When it is necessary to connect a circuit between the fuse bus bar and the relay bus bar, the bus bars of the circuit are connected by welding. Or,
A bus bar may be provided integrally. Further, the bus bar for the fuse and the bus bar for the relay are individually provided with a bus bar respectively connected to each terminal of the fuse and each terminal of the relay.

[0015]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic exploded perspective view of components constituting a junction box 10 connected to an automobile wire harness.

In FIG. 1, 11 is a lower case, 12 is an upper case, 13 is a connector module, 14 is a fuse module, and 15 is a relay module. Inside the case composed of the lower case 11 and the upper case 12, a connector module 13, a fuse module 1
4. The relay module 15 is housed.

The lower case 11 has a connector housing 1
A large number of relay housings 1a are provided, and a plurality of relay accommodating portions 11b are provided in series on one side in the long side direction in the long side direction. The upper case 12 is provided with a fuse accommodating portion 12a on one side in the short side direction. A connector housing 12e is provided on the peripheral wall on the other side in the short side direction. The lower case 11 and the upper case 12 are fitted to each other so as to be locked together by fitting the peripheral wall, and a bracket 12 d for fixing the vehicle body is protruded from the upper case 12.

In the connector module 13, the connector connection bus bars 16 are vertically stacked with an insulating plate 17 interposed therebetween. In this embodiment, the connector bus bars 16 have four layers. The connector module 13 shown in FIG. 1 is schematically illustrated with an insulating plate 17 disposed on the uppermost layer. The bus bar 16 and the insulating plate 17 may be formed by molding the bus bar 16 with a resin to form the insulating plate 17 and also integrate the multilayer bus bar 16.

Each layer of the connector connecting bus bar 16 of the connector module 13 is formed by punching one conductive plate to form a circuit portion 16a having a required shape. The circuit section 16
a welding tab 16 protruding from the upper case 11 to the lower case 11 side.
b, the connector housing 11 provided in the lower case 11
It protrudes from the terminal hole 11c of FIG. A connector (not shown) connected to the distal end of the wire harness is fitted into the connector accommodating portion 11a to connect the terminal in the connector to the tab 16b.

The required circuit portion 16a of the connector bus bar 16 has welding tabs 16c and 16d vertically protruding from holes in the upper surface of the insulating plate 17, and welding protruding horizontally from the peripheral edge of the insulating plate 17. Tab 16e is provided. The tabs 16c and 16e are tabs with the fuse bus bar 20 provided in the fuse module 14,
d is a relay bus bar 3 provided in the relay module 15.
It is a tab with 0.

That is, the tabs 16c and 16d are the welding tab 20a of the fuse bus bar 20 and the relay bus bar 3
No. 0 welding tab 30a is vertically overlapped and welded. The tab 16e is vertically overlapped and welded to the welding tab 20b of the fuse bus bar 20. These tabs 16
c, 16d, and 16e each protrude in parallel in large numbers. Then, the tabs 16c, 16d (20a, 20a, 16b) bent in the vertical direction in the connector module 13, the fuse module 14, and the relay module 15 are formed.
30a), as shown in FIG. 4, a protrusion dimension L1 protruding toward at least one of the mating surfaces toward the other side.
Are provided. This projection P is provided on each tab 16.
c, 16d, 20a, and 30a serve as welding points to facilitate welding when welding is performed by applying pressure to each other.
c, 16d, 20a, and 30a are surface-bonded.

The fuse module 14 has a configuration in which fuse bus bars 20 are arranged between two insulating plates 22A and 22B, and is formed by molding the fuse bus bars 20. Each of these bus bars for fuses 20 is individually provided with one that is connected to each of the terminals 25a and 25b of the fuse. As shown in FIG. 2 (with the insulating plate removed), the plurality of fuse bus bars 20 are
terminal portions 20c-1 and 20c at one end of each of e-1 and 20e-2.
-2 are bent and projected, and press-contact grooves 20d-1 and 20d into which the terminals 25a and 25b of the fuse 25 are fitted at the tip thereof.
-2 is provided. The ends of the bus bars 20 connected to the terminals 25a and 25b project from the peripheral edges in opposite directions to form the above-described tabs 20a and 20b. And
The one tab 20a is formed so as to project horizontally from one peripheral edge of the substrate 21 and then bend so as to rise in the vertical direction so as to overlap the tab 16c of the connector bus bar 16 on a vertical plane. The other tab 20b
The tab 16e of the connector bus bar 16 is projected from the peripheral edge of the other side in the horizontal direction and then bent downward in a step-like manner.
And overlap on the horizontal plane. still,
The fuse bus bar 20 may be provided with a caulking rib on an insulating plate, a hole formed in the bus bar, a bus bar disposed through the rib in the hole, and a caulked rib fixed.

The relay module 15 has substantially the same configuration as the fuse module 14, and includes upper and lower insulating plates 31A,
A large number of relay bus bars 30 are fixed between 31B, and these relay bus bars 30 are provided individually to be connected to the respective terminals of the relay, so that the bus bars are scattered. As shown in FIG. 3 (with the insulating plate removed), a large number of bus bars 30 are provided with a terminal portion 30c protruding by bending one end of a horizontal portion 30b fixed to the insulating plate, and a relay 35 at the end thereof. A press contact groove 30d into which the terminal 35a is fitted is provided. The other end of the bus bar 30 is the above-described tab 30a, which is bent into an L shape so as to be vertically joined to the tab 16d of the connector bus bar 16.

Next, for the connector module 13,
When the fuse module 14 and the relay module 15 are horizontally overlapped, the tabs 16c and 20a and the tab 16d,
The configuration for positioning when welding 30a will be described. As shown in FIG. 1, a pair of bosses 51 project from the connector module 13 and the fuse module 14 at both ends of the arrangement position on the insulating plate 17 in the vertical direction. On the other hand, a boss hole 52 for positioning into which the boss 51 can be fitted is formed at a position corresponding to the insulating plates 22A and 22B of the fuse module 14. The boss hole 52 moves from a standby position where the projections P are separated by the dimension L1 when the tabs 16c and 20a are overlapped, to a joining position where the projections P are crushed by welding and the mating surfaces of the tabs 16c and 20a abut. Are elongated in a direction that allows the above.

When the tabs 16c, 20a are welded to the insulating plates 17, 22A, 22B of the connector module 13 and the fuse module 14 at the joining position, a pair of positioning holes 53, 54 communicating with each other are formed in the bosses. 51
And boss holes 52. At a required position of the lower case 11 corresponding to the positioning holes 53 and 54, a pair of positioning pins 55 projecting from the communicating positioning holes 53 and 54 are provided.

Similarly, between the connector module 13 and the relay module 15, a pair of bosses 56 are protruded from the lower surface of the insulating plate 17 on which the connector module 13 is to be disposed, and the insulating plates 31A and 31B Has a boss hole 57 composed of a long hole corresponding to this. Similarly, a pair of positioning holes 58 and 59 communicating with each other are provided at the joint positions of the tabs 16d and 30a after welding, and the positioning holes 58 and 5 are formed in the lower case 11.
9, a pair of positioning pins 60 that can be inserted are projected. In this embodiment, the positioning hole 58 for the relay module 15 in the connector module 13 is used.
Is shared with the positioning hole 53 for the fuse module 14, and similarly, the positioning pin 6 in the lower case 11 is formed.
0 is shared with the positioning pin 55. Of course, depending on the arrangement of the relay module 15,
These positioning holes 58 and positioning pins 60 may be set at separate positions.

When assembling the junction box 10 from the above components, first, the connector module 13
The fuse module 14 is disposed on the upper side of one side. At this time, as shown in FIGS. 5A and 5B, by fitting the boss 51 of the connector module 13 into the boss hole 52 of the fuse module 14, the corresponding tabs 16c and 20a are vertically aligned. So that it is superimposed on top. At this time, a standby position having a required interval is provided between the mating surfaces due to the presence of the protrusion P protruding from the tab 20a, and the boss 51 is fitted into a position of the boss hole 52 biased toward the tab 20a. Next, when the corresponding tabs 16c and 20a are welded while compressing each other by, for example, a resistance welding machine (not shown), the projection P becomes a welding point and is crushed, so that as shown in FIGS. 6A and 6B. , Tabs 16c and 20a relatively move to the joint position where the mating surfaces abut. That is, the movement between the connector module 13 and the fuse module 14 is performed by the boss 51 and the boss hole 52.
And the tabs 16c and 20d are restricted to be allowed to move only in the direction from the standby position to the joining position.
c, adjacent tabs 16 even if the pitch of 20d is narrow
c, 20d can be prevented from contacting. After the completion of the welding, the boss 51 has been moved to the other end of the boss hole 52. The tab 16e projecting horizontally from the periphery of the connector module 13 corresponds to the fuse module 1
The connector module 13 and the fuse module 14 are joined by superimposing and welding tabs 20b projecting horizontally from the other peripheral edge of the connector 4 on the other side.

Although the detailed description is omitted, when the relay module 15 is disposed on the lower surface of the connector module 13 in the same manner as in the case of the fuse module 14, the welding direction by the boss 56 and the boss hole 57 is also determined. The two are joined by using movement restrictions.

As described above, the fuse module 14 is mounted on the upper part of the short side of the connector module 13,
After arranging and integrating the relay module 15 on the side of the long side, these are accommodated in the lower case 11. At this time, the connector module 13 and the fuse module 1
The positioning holes 53 and 54 provided between the connector module 13 and the positioning holes 58 and 59 provided between the connector module 13 and the relay module 15 are shown in FIG. As described above, the shafts are in a penetrating state in which their axes coincide with each other. Then, the positioning holes 53, 54
As shown in FIG. 7, the corresponding positioning pins 5 protruding from the lower case 11 with respect to the positioning holes 58 and 59.
5 and 60 are inserted so that the connector module 13 is inserted.
In the lower case 11. By the assembly, the terminal portion 16b of the connector module 13 is located in the connector housing portion 11a, and the terminal portion 30c of the bus bar of the relay module 15 is located in the relay housing portion 11b.

Next, an electronic control unit (not shown) is mounted above the connector module where no fuse module is mounted. Then, upper case 1
Assemble 2. At that time, the terminal portion 20c of the fuse bus bar 20 fixed to the fuse module 14 is arranged in the fuse accommodating portion 12a of the upper case 12. Then, the upper case 12 and the lower case 11 are locked and connected to each other, whereby the assembly of the junction box 10 is completed.

When the fuse 25 and the relay 35 are inserted into the junction box 10 into the fuse accommodating portion 11a and the relay accommodating portion 11b, respectively, they are fitted and connected to the press contact grooves 20d and 30d of the bus bars 20 and 30, respectively.

In the above embodiment, the fuse module and the relay module are separated from each other. However, a composite module in which the fuse module and the relay module are integrated may be used. In that case, FIG.
As shown in (B), the upper case 12 'is provided with a fuse accommodating portion 12a' and a relay accommodating portion 12b 'in which terminal portions of bus bars provided in the composite module are located. Further, the lower case 11 'is provided with only the connector accommodating portion 11a' where the terminal portion of the bus bar of the connector module is located. Further, in the above embodiment, the example in which the bosses 51 and 56 are provided on the connector module 13 side is shown. However, the bosses 51 and 56 are provided on the fuse module 14 side and the relay module 15 and the boss holes 52 and 57 are provided on the connector module 13 side. May be provided. As the welding means in the above embodiment, ultrasonic welding, laser welding, or the like can be employed in addition to resistance welding.

The junction box of the present invention is not limited to the above embodiment, and the connector module, the fuse module, and the relay module are further divided into two.
Each of them may be composed of two divided modules. When the connector module, the fuse module, and the relay module are divided, when the specifications of the connector connection circuit, the fuse connection circuit, and the relay connection circuit are changed, only the changed module needs to be replaced. However, if it is divided too much, it takes time to assemble the connector module. Therefore, in a large junction box, it is preferable that each of the connector module, the fuse module, and the relay module is divided into about two.

A bus bar for connector connection of the connector module, a bus bar for fuse of the fuse module,
The welding pattern of the relay bus bar of the relay module has the following pattern according to the circuit design. Bus bar for connector and bus bar for fuse Bus bar for connector connection and bus bar for relay Bus bar for connector connection, bus bar for fuse and bus bar for relay In this case, fuse bus bar is welded to the tab at one end of connector bus bar for one circuit Then, the relay bus bar is welded to the tab at the other end of the connector bus bar, and the tab provided on the other portion of the connector bus bar is connected to the connector.

[0035]

As is apparent from the above description, according to the junction box of the present invention, a connector module provided only with a bus bar for connector connection, a fuse module provided only with a bus bar for fuse connection, and a bus bar for relay connection Since the relay module with only the relay is provided separately and the bus bar is divided, the tab for connecting to the connector, fuse, relay is inevitably located at another position and does not overlap, and as a result, the tab is provided Therefore, it is not necessary to increase the number of stacked bus bars. as a result,
The thickness of the junction box can be reduced.
And, at the time of welding, since the positioning can be performed by the boss and the boss hole provided between each module, and the positioning pin and the positioning hole, the tabs arranged at a narrow pitch can be welded to an accurate position without being shifted and joined. When the module is accommodated in the lower case, it can be accommodated without displacement.

Further, since the bus bar is divided as described above, the layout of the bus bar circuit becomes simple and the required area can be reduced. As a result, even if the bus bars are divided and the ends of the bus bars are connected by welding, the occupied area does not increase as a whole, and the area of the junction box does not increase.

Further, if there is a change in the specifications of the connector connection circuit, the fuse connection circuit, and the relay connection circuit, only the connector module, the fuse module, the relay module whose specification has been changed, or a composite module thereof may be changed. Module, upper case, and lower case can be shared, so that it is possible to respond quickly and inexpensively to specification changes.

[Brief description of the drawings]

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

FIG. 2 is a schematic diagram showing a fuse bus bar.

FIG. 3 is a schematic view showing a relay bus bar.

FIG. 4 is a cross-sectional view of a main part in a state where the connector module and the fuse module are overlaid.

FIG. 5A is a plan view showing a state before welding in which a fuse module and a relay module are superimposed on a connector module, and FIG. 5B is a cross-sectional view of a main part.

6A is a plan view of a state after welding in which a fuse module and a relay module are superimposed on a connector module, and FIG. 6B is a cross-sectional view of a main part.

FIG. 7 is a cross-sectional view of a main part in a state where a lower case is further fitted to the state of FIG. 6 (B).

8A and 8B show another embodiment, in which FIG. 8A is a plan view and FIG.
Is a bottom view.

FIG. 9 is an exploded perspective view showing a conventional junction box.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Junction box 11 Lower case 12 Upper case 13 Connector module 15 Relay module 16 Connector connection bus bar 16c, 16d tab 16e tab 17 Insulating plate 20 Fuse bus bar 20a tab 20b Tab 22A, 22B Insulating plate 30 Relay bus bar 51 Boss 52 Boss hole 53, 54 Positioning hole 55 Positioning pin 56 Boss 57 Boss hole 58, 59 Positioning hole 60 Positioning pin P Projection

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 5/02 H05K 5/02 Z (72) Inventor Tatsuya Kadota 1-14 Nishisuehirocho, Yokkaichi-shi, Mie Prefecture Sumitomo Wiring Systems F term (reference) 4E360 AB14 AB20 CA02 EA24 EC05 ED04 ED07 ED27 FA17 GA06 GA52 GA53 GB93 GB94 5E085 BB06 CC03 CC08 DD03 DD04 EE02 HH11 HH12 HH13 JJ31 JJ36 JJ38 5G361 BA04 BB01 BC05 CC51

Claims (4)

[Claims] 1. A connector connection circuit section, a fuse connection circuit section, and / or a relay connection circuit section accommodated in an upper case and a lower case of a junction box are divided into separate connector modules, fuse modules, and / or relay modules. A fuse module and / or a relay module are disposed on the connector module so as to overlap with each other in a horizontal direction. Each of the modules includes a bus bar fixed to an insulating plate, and each of the bus bars has a tab bent in a vertical direction. Then, overlap the tabs of the above modules,
A projection projecting toward the other side is provided on the mating surface of one of the tabs, and the projection is crushed and welded at the time of welding, wherein the connector module and the fuse module and / or the relay are arranged in an overlapping manner. A boss protrudes vertically to one of the module's insulating plates,
Either one is provided with a positioning boss hole into which the boss can be fitted when the tabs are welded, and the boss hole is crushed from a standby position where the tabs are separated from each other by the protrusion, and the tabs are separated from each other. A junction box comprising a long hole extending in a direction allowing movement to a joining position where the mating surface of the junction box abuts. 2. A positioning hole is formed in a corresponding portion of the upper and lower insulating plates at a joint position after welding in the insulating plates of the modules arranged in an overlapping manner, and is inserted into the positioning hole in the lower case. 2. The junction box according to claim 1, wherein possible positioning pins protrude. 3. The connector connection circuit section, the fuse connection circuit section and / or the relay connection circuit section accommodated in the upper case and the lower case of the junction box are divided into separate connector modules, fuse modules and / or relay modules. Each of the modules includes a bus bar fixed to an insulating plate, and has a tab whose end portion is bent in a direction perpendicular to the plane of the insulating plate. Of the tabs, the mating surface of the superposed tabs is provided. At least one is provided with a protruding portion protruding toward the other side, and when arranging the fuse module and / or the relay module in a horizontal direction on the connector module, vertically protruding from one of the insulating plates. Boss that has a long hole on either side The tabs are overlapped on a vertical plane via the protrusions, and then welded while compressing the tabs, and at the same time, are relatively moved with the collapse of the protrusions. The method of assembling a junction box, wherein the movement between the stacked modules is absorbed by a long hole of the boss hole in which the boss is fitted. 4. A positioning pin projecting from the lower case is inserted into a positioning hole provided at a corresponding position between insulating plates of the module when the module after being welded by the tab is arranged in the lower case. 4. The method for assembling a junction box according to claim 3, wherein said upper case is fitted to said lower case.