JPH11297373A - Laser welded structure for bus bar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize a connection characteristic by rivet-caulking the bend margin section of a tab terminal to a bus bar, and laser-welding the bend margin section to the bus bar at positions different from rivet caulking. SOLUTION: Rivet holes 4c, 4d are bored on the bend margin section 4b of a tab terminal 4a and a separate bus bar 4 respectively, and the bend margin section 4b of the tab terminal 4a is mounted on the bus bar 4, so that the rivet holes 4c, 4d match with each other. The bend margin section 4b is rivet-caulked to the bus bar 4 by a rivet 6 inserted into the rivet holes 4c, 4d. The bend margin section 4b of the tab terminal 4a is connected to the bus bar 4, by laser-welding (a) at positions different from rivet caulking. The bend margin section 4b is rivet-caulked to the bus bar 4, and the dispersion of connection strength is reduced. Since the rivet 6 is laser-welded, specially ordered rivet is not required, and the cost can be reduced.

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. 6, there is an electric connection box in which a plurality of bus bars 4 are stacked and housed 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. 7, the present applicant increases the wiring space by laminating the bus terminals 4 by welding a laser beam LB to the bus terminals 4 with the tab terminals 4a provided separately. 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, since the bent portion of the tab terminal 4a is joined to the bus bar 4 only by laser welding, variations in connection characteristics such as connection strength and connection resistance are reduced. In some cases, the connection characteristics become unstable.

As shown in FIG. 5, there has been proposed an apparatus in which the bus bar 4 (or the tab terminal 4a) is caulked with a rivet 5 and the rivet 5 is laser-welded to the bus bar 4 with a laser beam LB. In addition, a custom-made rivet 5 made of a metal material having a low reflectance of laser light is required, which increases the cost. In the rivet swaged portion, the connection characteristics of the bent portion of the bus bar 4 and the tab terminal 4a are stable. However, as the distance from the rivet swaged portion increases, the connection characteristics vary widely due to the warpage of the tab terminal 4a. There is.

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 having a stable connection characteristic.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to 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 connected to the bus bar. It is another object of the present invention to provide a laser welding structure for a bus bar, wherein a rivet is swaged and the bent portion is laser-welded to the bus bar at a position different from the rivet swaging.

According to the present invention, the bent portion of the tab terminal is riveted to the bus bar to reduce the variation in connection strength, and at the same time, the bent portion is laser-welded to the bus bar at a position different from that of the rivet. Thus, the variation in connection resistance is reduced.

[0011]

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.

As shown in FIGS. 1 and 2, a rivet hole 4 is formed in a margin 4b of a separate tab terminal 4a and a bus bar 4.
The rivets 6 are inserted into the rivet holes 4c and 4d by placing the bent portions 4b of the tab terminals 4a on the upper surface of the bus bar 4 such that the rivet holes 4c and 4d coincide with each other by making holes c and 4d. Then, the bent portion 4b of the tab terminal 4a is riveted to the bus bar 4.

The tab terminal 4a has a bent portion 4
b is bonded to the bus bar 4 by laser welding a with a laser beam LB at a position different from the rivet setting. In this example,
Laser welding a is performed at two places before and after rivet caulking.

In the above-described laser welding structure, since the bent portion 4b of the tab terminal 4a is riveted to the bus bar 4, the dispersion of the connection strength is reduced, and at the same time, the bent portion 4b is formed differently from the rivet setting. Since laser welding a is performed on the bus bar 4 at the position, the variation in the connection resistance is reduced. That is, since the connection strength is covered by the rivet 6 and the connection resistance is covered by the laser welding a, connection characteristics such as connection strength and connection resistance are stabilized.

Further, since the rivet 6 is not laser-welded as in the prior art, there is no need for a custom-made rivet made of a metal material having a low laser light reflectance, so that the cost is reduced. further,
Even if the bent portion 4b of the tab terminal 4a is warped at a position away from the rivet caulking portion, since the bent portion 4b is completely joined to the bus bar 4 by laser welding a, the variation in connection characteristics is reduced.

FIG. 3 shows a first modification, in which a tab terminal 4a is provided.
Of the bent part 4b at two places before rivet caulking and one place after
Laser welding a is performed at a total of three locations. This allows
Even if a forward / backward tilting force acts on the tab terminal 4a, the laser welds a at the two front positions are less likely to peel off.

FIG. 4 shows a second modification, in which a tab terminal 4a is provided.
Are set to the two-pin structures 4a-1 and 4a-2, so that they can be adapted to narrow-pitch connectors.

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 of the present invention, the laser beam LB is non-contact compared with the above-described resistance welding, arc welding, ultrasonic welding, etc. In addition, the tab terminal 4a can be welded to the bus bar 4 and the welding time per spot is short, so that mass productivity is good. Further, since the laser beam LB has a small beam diameter, the bus bar 4 and the tab terminal 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.

Among various laser weldings, the 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.

[0021]

As is clear from the above description, the laser welding structure of the bus bar according to the present invention reduces the variation in connection strength by riveting the bent portion of the tab terminal to the bus bar, and at the same time reduces the bending. The margin is laser-welded to the bus bar at a position different from the rivet caulking to reduce the variation in connection resistance, so that connection characteristics such as connection strength and connection resistance are stabilized.

[Brief description of the drawings]

FIG. 1 is a perspective view of a laser welding structure of the present invention.

FIG. 2 is a side sectional view of a laser welding structure.

FIG. 3 is a perspective view of a laser welding structure according to a first modified example.

FIG. 4 is a perspective view of a laser welding structure according to a second modification.

FIG. 5 is a perspective view of a conventional laser welding structure.

FIG. 6 is an exploded perspective view of a conventional electric junction box.

FIG. 7 is a side view of a prior art bus bar laser welding structure.

[Explanation of symbols]

 4 Bus bar 4a Tab terminal 4b Bending margin 4c, 4d Rivet hole 6 Rivet LB Laser beam a Laser welding

Claims (1)

[Claims] 1. A structure in which a tab terminal is laser-welded to a bus bar housed in an electric junction box, wherein a bent portion of the tab terminal is riveted to the bus bar, and the bent portion is connected to the rivet caulking. A laser welding structure for a bus bar, wherein laser welding is performed on the bus bar at another position.