JPH11297372A - Laser-welded structure for bus bar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize a connection characteristic, without increasing a connection space by aligning the bend margin section of a tab terminal on the same plane as a bus bar, and welding the boundary face between the bend margin section and the bus bar by laser. SOLUTION: Machining such as notching is not required for a bus bar 4, the bend margin section 4b of a tab terminal 4a is aligned on the same plane as that of the bus bar 4, one side section of the bend margin section 4b is butted to the side section of the bus bar 4 without a gap, and the boundary face is welded and connected at multiple positions by a laser beam LB. Since there is not overlap, the thickness of the laser-welded portions is not increased, laser conditions can be easily adjusted, and the dispersion of connection strength and connection resistance is reduced. A recessed notch is also preferably formed on the side section of the bus bar 4 to laser-weld the boundary face, where the side section of the bend margin section 4b is inserted and abutted to the notch.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser welding structure most suitable for a bus bar housed in an electric junction box.

[0002]

2. Description of the Related Art An electrical junction box used for branch connection of a wiring harness for automobiles to various electric components is provided with branch connection points concentrated at one place, and wiring is rationally and economically connected. With the increase in the density of wire harnesses, various types have been developed according to vehicle types or applications.

As shown in FIG. 5, there is an electric connection box in which a plurality of bus bars 4 are stacked and accommodated in an upper case 1 and a lower case 2 via an insulating plate 3 as shown in FIG. .

In the case where the tab terminals 4a are integrally bent and formed on the bus bar 4, the wiring space is reduced only in the unfolded portion of the tab terminals 4a, and in order to secure the reduced wiring space. In this case, it is necessary to increase the number of stacked bus bars, so that the electric connection box is thickened.

For this reason, as shown in FIG. 6, the present applicant increases the wiring space by welding the laser beam LB to the bus bar 4 with the tab terminal 4a as a separate member, thereby increasing the stacking of the bus bar. A laser welding structure for a bus bar, in which the number of the electric junction boxes can be reduced by reducing the number, has been previously proposed (see Japanese Patent Application No. 9-138369).

[0006]

In the above-described laser welding structure for a bus bar, the bus bar 4 is overlapped with the bent portion of the tab terminal 4a, and the overlapped portion whose thickness is doubled is laser-welded. When the tab terminal 4a is made of a material having a large laser reflectance, such as copper, by laser welding, it is difficult to adjust the laser conditions, and the connection characteristics such as the connection strength and the connection resistance vary greatly. Characteristics may not be stable.

An object of the present invention is to improve the laser welding structure of a bus bar according to the proposal of the present applicant, and to provide a laser welding structure of a bus bar in which the connection characteristics are stable and the connection space does not increase. Is what you do.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention has a structure in which a tab terminal is laser-welded to a bus bar housed in an electric junction box, and a bent portion of the tab terminal is connected to the bus bar. An object of the present invention is to provide a laser welding structure for a bus bar, which is arranged in a plane and laser-welds the interface between the bent portion of the tab terminal and the bus bar.

According to the present invention, the interface between the bus bars arranged in a plane and the bent portion of the tab terminal is joined by laser welding.

According to a second aspect of the present invention, a notch is formed in the bus bar, and a bent portion of the tab terminal is fitted into the notch, and an interface between the bent portion of the tab terminal and the notch of the bus bar is formed. Laser welding is preferred.

Preferably, the notch is a concave notch as defined in claim 3 or a cut-shaped notch as defined in claim 4.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the same components and operations as those of the prior art are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 shows a laser welding structure according to a first embodiment. The bus bar 4 does not need to be cut or the like, and the margin 4b of the separate tab terminal 4a is arranged in a plane with the bus bar 4, and one side of the margin 4b and the side of the bus bar 4 are connected. Match without gaps.

The tab terminal 4a has a bent margin 4
A plurality of portions of the interface A between the side portion b and the side portion of the bus bar 4 are joined by laser welding with a laser beam LB.

In the laser welding structure according to the first embodiment, the thickness of the laser welded portion does not increase because the bus bar 4 is merely overlapped with the bent portion 4b of the tab terminal 4a and not overlapped as in the prior art. Adjustment of laser conditions is easy, and variations in connection characteristics such as connection strength and connection resistance are reduced, so that connection characteristics are stabilized.

FIG. 2 shows a laser welding structure according to a second embodiment. A concave notch 4c is formed on the side of the bus bar 4,
The notch 4c has a bent portion 4b of a separate tab terminal 4a.
The bus bars 4 are arranged in a plane while being fitted, and the side portions of the bent portions 4b and the side portions of the notches 4c of the bus bars 4 are butted against each other without any gap.

The tab terminal 4a has a bent portion 4
Interface A between the side of b and the side in notch 4c of bus bar 4
Are joined by laser welding with a laser beam LB.

In the laser welding structure of the second embodiment, the first
In addition to the effect similar to the embodiment, the notch 4 of the bus bar 4
Since the bent margin portion 4b of the tab terminal 4a is fitted into c, the connection space as in the first embodiment increases. Further, the tab terminal 4a is provided in the notch 4c
Can be accurately set, the displacement of the tab terminals 4a can be prevented, the defects due to the displacement can be reduced, and the quality can be stabilized.

FIG. 3 shows a third embodiment. A cutout notch 4d is formed at a predetermined position of the bus bar 4, and the cutout 4c is fitted with the bent margin 4b of the separate tab terminal 4a while being arranged in a plane with the bus bar 4 to form a bent margin 4b.
And the front and rear portions of the notch 4c of the bus bar 4 are butted against each other without any gap.

Then, the bent portion 4 of the tab terminal 4a is formed.
The interface A between the front and rear portions b and the front and rear portions in the notches 4c of the bus bar 4 is joined by laser welding with a laser beam LB.

In the laser welding structure of the third embodiment, the second
The same effect as the embodiment can be obtained.

FIG. 4 shows a fourth embodiment. A recessed notch 4c and a cutout notch 4d are formed at predetermined positions of the bus bar 4, and a separate tab terminal 4a is formed in the recessed notch 4c.
Bus bar 4 while fitting the rear portion of
And the bus bar 4 and the rear portion of the bent portion 4b.
Of the tab terminal 4a and a plurality of portions of the interface A between the rear portion and the side portion of the notch 4c of the bus bar 4 with the rear portion and the side portion of the tab terminal 4a. Laser welding is performed using the beam LB.

Further, the cut-out notch 4d is arranged in a plane with the bus bar 4 while abutting the rear ends of the bent portions 4b of the separate tab terminals 4a. 4 and the end of the notch 4d of the tab terminal 4a is welded by a laser beam LB to the interface A between the rear end of the bent portion 4b of the tab terminal 4a and the end of the notch 4d of the bus bar 4. To join.

In the laser welding structure of the fourth embodiment, the second
The same effect as the embodiment can be obtained.

When the tab terminals 4a are welded to the bus bar 4, if conventional resistance welding is used, a large jig is required for each bus bar to sandwich the bus bar between the electrodes.
Processing man-hours and equipment become expensive, which is not suitable for mass production. In the case of conventional arc welding, since the gap between the busbar and other circuits is narrow, it is necessary to insulate or widen the gap, so that the density cannot be increased, and it is necessary to ground each circuit to be welded. Therefore, processing man-hours and the like become expensive, which is not suitable for mass production. Furthermore, in ultrasonic welding, partial plating is necessary because welding cannot be performed on a portion of the bus bar that has plating, and the bus bar shape is different one by one, so jigs are required for the number of circuits, so processing man-hours and equipment are required. However, they are expensive and unsuitable for mass production.

On the other hand, in the case of the laser welding according to the present invention, the laser beam LB is not in contact with the above-described laser welding, arc welding, ultrasonic welding, etc. In addition, the tab terminals 4a can be welded to the bus bar 4 and the welding time per one place is short, so that mass productivity is good. Also, since the laser beam LB has a small beam diameter, the bus bar 4 and the tab terminals 4a are connected to each other. There is an advantage that the pitch can be narrowed, and the degree of freedom in design wiring is improved.

[0027] Of the various types of laser welding, YAG laser welding is non-contact, has a small heat-affected layer,
It has low power consumption, is small in size, can be easily used for three-dimensional welding due to the use of optical fibers, and can divide a beam into multiple parts for simultaneous multipoint welding.
It is optimal because the automation is easy and the production cost is significantly reduced.

[0028]

As is clear from the above description, the laser welding structure for a bus bar according to the present invention is arranged such that the bus bar and the tab terminal bend portions are arranged in a plane and these interfaces are joined by laser welding. Since the thickness of the laser welded portion does not increase, the adjustment of the laser condition is easy, and the dispersion of the connection characteristics such as the connection strength and the connection resistance is reduced, so that the connection characteristics are stabilized.

According to a second aspect of the present invention, a concave notch (claim 3) or a cut-out notch (claim 4) is formed in the bus bar, and a bent portion of a tab terminal is fitted into the notch. When the interface between the bent portion of the tab terminal and the cutout of the bus bar is laser-welded, the bent portion of the tab terminal is fitted into the cutout of the bus bar, thereby increasing the connection space. In addition, since the tab terminals can be accurately set in the cutouts of the bus bar, positional deviation of the tab terminals can be prevented, defects due to positional deviation are reduced, and quality is stabilized.

[Brief description of the drawings]

FIG. 1 is a perspective view of a laser welding structure according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a laser welding structure according to a second embodiment.

FIG. 3 is a perspective view of a laser welding structure according to a third embodiment.

FIG. 4 is a perspective view of a laser welding structure according to a fourth embodiment.

FIG. 5 is an exploded view of a conventional electric junction box.

FIG. 6 is a side view of a laser welding structure of a prior art bus bar.

[Description of Signs] 4 Bus bar 4a Tab terminal 4b Bending margin 4c Concave notch 4d Cut notch A Interface LB Laser beam

Claims (4)

[Claims] 1. A structure in which a tab terminal is laser-welded to a bus bar housed in an electric connection box, wherein a bent portion of the tab terminal is arranged in a plane with the bus bar, and the bent portion of the tab terminal is connected to the bus bar. A laser welding structure for a bus bar, wherein the interface is laser-welded. 2. A notch is formed in the bus bar, a bent portion of the tab terminal is fitted into the notch, and an interface between the bent portion of the tab terminal and the notch of the bus bar is laser-welded. 2. The laser welding structure for a bus bar according to 1. 3. The laser welding structure for a bus bar according to claim 2, wherein the notch is a concave notch. 4. The laser welding structure for a bus bar according to claim 2, wherein the notch is a cut-shaped notch.