JPH10188940A - Cell-to-cell connection method for storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always keep a good welded condition and improve the strength of a welded part for a longer life and vibration proofing ability without decreasing productivity and increasing the cost. SOLUTION: In this connection method, connection plates 5, 6 are arranged at both sides of a through-hole 2 in a partition wall 1 and pressure-deformed with a pair of welding electrodes 7, 8 having protrusion 9, 10 to be pressed into the through-hole 2. A pair of cell-to-cell connection welding electrodes 7, 8 for a storage battery to be resistance-welded have the first protrusions 9 with the smooth faces being larger than the diameter of the through-hole 2 in the partition wall 1 and the second welding protrusions 10 provided on the first protrusions 9 with the diameters at the lower ends being smaller than the diameter of the through-hole 2. At least one of the welding electrodes 7, 8 has limited electric continuity between the welding electrode and a connection plate only at the second protrusions 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for connecting cells of a storage battery.

[0002]

2. Description of the Related Art Rechargeable batteries are used in many applications from small-capacity consumers to large-capacity stationary devices, such as starting and lighting vehicles. In recent years, it has also attracted attention as a power source for electric vehicles from the viewpoint of environmental issues.

[0003] The storage battery used for these has a plurality of divided cells, and is connected to adjacent cells to form a structure having a high voltage such as 6 V or 12 V in one battery case. I have. Various connection methods are used between cells, and a resistance welding method is often used for a lead-acid battery used for starting and lighting an automobile.

That is, as shown in Japanese Patent Application Laid-Open No. 55-139761, in a synthetic resin container having a plurality of divided cells, a partition wall for partitioning each cell is provided with a through hole. Connecting plates extending from the electrode group straps of both cells and having different polarities are arranged on both sides of the through hole, and the connecting plate made of a lead alloy is pressed by a pair of welding electrodes having projections to form the through hole. The connection plates were pressed into each other, and a current was applied to the welding electrodes in a state where both connection plates were in contact with each other to perform resistance welding. .

[0005]

When connection between cells is performed by the conventional method, when pressurizing and resistance welding by a welding electrode, lead is formed from a thermal deformation of a synthetic resin container or a connection portion to be accommodated in a through hole. Manufacturing defects such as popping out sometimes occurred. This phenomenon is likely to occur when performing continuous operations in the process.This is because the welding electrode is heated by performing the resistance welding process continuously, and the connection plate is excessively heated more than the set value. It seems to happen.

There is also a method in which members are cast in advance between cells as disclosed in Japanese Patent Application Laid-Open No. 55-62659. However, in this method, although a good inter-cell connection portion can be obtained, it is costly and problematic to cast a lead component into the battery case.

[0007]

According to the method for connecting cells of a storage battery according to the present invention, connecting plates of adjacent cells are arranged on both sides of a through hole provided in a partition wall, and both connecting plates are provided with a pair of welding electrodes having projections. In the cell-to-cell connection method, pressurizing, deforming and press-fitting into the through-hole, applying current and performing resistance welding, and pressurizing the periphery of the welded portion to closely adhere to the partition, the welding electrode is a partition of the battery case. A first projection for maintaining airtightness having a smooth surface larger than the diameter of the through hole, and a second projection for welding provided on the first projection, the upper end having a diameter smaller than the diameter of the through hole. It consists of a pair having two projections, and at least one of the pair of welding electrodes limits the electrical conduction between the welding electrode and the connection plate at the time of resistance welding to only the second projection portion. It is characterized by.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The method for connecting cells of a storage battery according to the present invention is a method of connecting cells between cells by penetrating a partition wall. A first projection for the first projection,
The diameter of the upper end portion uses a pair having a second projection for welding smaller than the diameter of the through-hole, at least one of the pair of welding electrodes is a welding electrode and a connection plate at the time of resistance welding. Is limited to only the portion of the second protrusion. By doing so, it is possible to prevent poor welding such as thermal deformation of the synthetic resin battery case and lead protrusion from the connection portion, and to provide a good inter-cell connection portion at all times.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case where the present invention is applied to a lead storage battery will be described below.

FIG. 1 is a sectional view of an essential part for explaining one embodiment of the inter-cell connection method of the present invention. First, a partition wall 1 for partitioning each cell of a polypropylene synthetic resin container having six cells. Was provided with a through hole 2. Next, connecting plates 5 and 6 made of lead alloys having different polarities were arranged on both sides of the through hole 2, extending from the straps 3 and 4 of the electrode plate group of the cell on both sides of the through hole 1. Here, the electrode plate group is commonly used in a lead storage battery, and is obtained by alternately stacking a positive electrode plate, a negative electrode plate, and a separator.

Connection plates 5 and 6 arranged on both sides of through hole 2
Is pressed by a pair of welding electrodes 7 and 8 having projections,
It is deformed and press-fitted into the through-hole, and at the same time, current is passed between the welding electrodes to weld the connection plates by resistance. Connection was made.

The welding electrodes 7 and 8 used here were used.
As shown in FIG. 1, a first projection 9 having a circular smooth surface larger than the diameter of the through hole 2, and a second projection 9 provided on the first projection 9, the upper end having a diameter smaller than the diameter of the through hole 2. Protrusion 1
In order to limit the electrical continuity between the connection plate and the welding electrode during resistance welding to only the second projection portion, the other welding projection surfaces have It was covered with an insulator 11 having strength. As the insulator, for example, ceramics, an insulating paint, an insulating sheet, or the like can be used. Here, a ceramic insulator is used.

A pair of welding electrodes having such a structure is used, and the diameter of the upper end of the second projection 10 is set to 10, 20, 40, 70, and 90% of the diameter of the through hole 2 to connect the cells. Was tested.

Further, as one embodiment of the inter-cell connection method of the present invention, as shown in FIG. 2, the electrical conduction between the connection plate and the welding electrode during resistance welding is limited to only the upper end of the second projection. A welding method using a welding electrode with other parts insulated as described above was also performed. At this time, the upper end diameter of the second projection 10 was 40% of the diameter of the through hole 2.

Here, the reason why the diameter of the upper end of the first protrusion of the welding electrode is made larger than the diameter of the through hole is that the flat plate at the upper end presses the welding plate and the partition wall around the through hole is pressed. This is for bringing the welding plate into close contact.

As a welding method according to the prior art, a resistance welding method using a welding electrode which has a projection having a two-stage structure as in the present invention but does not limit electric conduction to a part was performed for comparison. The welding electrode according to the conventional method does not have a portion covered with an insulator, and can be energized over the entire surface in contact with the connection plate.

Using these welding methods, resistance welding was continuously performed on 1,000 pieces each, and the welding state was examined.
The investigation was conducted by measuring the force required to thread the weld and visually confirming whether or not lead had popped out. Table 1 shows the average value of the force required for thread cutting and the number of lead protrusions.

[0018]

[Table 1] According to the invention of the present application, the upper end integrated with the welding electrode has a flat and tapered two-stage conical projection, the upper end diameter of the first projection is larger than the diameter of the through hole, The diameter of the upper end of the protrusion is 20 to 90% of the diameter of the through-hole. In the method in which the current is applied only to the surface of the protrusion, the protrusion of lead was not confirmed, and the force required for threading was larger than that of the conventional method. In the conventional method, lead outflow was confirmed in five out of 1,000 samples.

FIG. 3 shows a cross section of a weld according to the present invention.
Here, 1 is a partition partitioning the cell, 5 and 6 are connection plates, 7 and 8 are welding electrodes, and 9 and 10 are first projections and second projections on the welding electrodes, respectively. 1
Numeral 2 is a portion melted during welding. In the resistance welding method according to the present invention, since the current flows intensively at the central portion, the molten portion 12 at the time of welding spreads elliptically around the central portion of the contact point of the connecting plates, and the area of the welded portion is large. Further, it is considered that the reason why lead jumped out was small is that the dissolution spreads in a circular shape. Further, it is considered that the current efficiency was improved by concentrating the current at the center, and the excessive heating of the welding bar was reduced, which also contributed to the reduction of defects.

On the other hand, in the conventional method, the current-carrying portion is the entire contact surface between the welding electrode and the connection plate, and since the dissolution proceeds uniformly from the entire surface, as shown in FIG. Was only the contact portion. For this reason, it seems that the welding strength was slightly lower than that of the present invention. In addition, in the present method, since the current also flows from places other than the protrusions, it is considered that the connection plate and the welding electrode are excessively heated, and as a result, lead is likely to jump out.

In the present invention, an excellent welding state was obtained for the same reason even when a welding electrode insulated at other portions so that the current-carrying portion was formed only at the upper end portion of the second-stage projection.

In the above embodiment, the case where the electrical conduction is limited to the second protruding portion for both of the pair of welding electrodes is shown. However, even when only one of the electrodes has such an electrode configuration, substantially the same effect can be obtained. It was confirmed that it could be obtained.

As described above, a good welding condition is always obtained by limiting the energized portions by the welding method according to the present invention, and the strength of the welded portion is also increased.

[0024]

As described above, according to the present invention, a good welding condition can always be obtained, and the strength of the welded portion can be increased.
Therefore, it is expected that the life performance and the seismic resistance can be improved, and these can be performed without lowering the productivity or increasing the cost. Therefore, the present invention has a very industrial value.

[Brief description of the drawings]

FIG. 1 is a sectional view of an essential part for explaining an embodiment of the inter-cell connection method of the present invention.

FIG. 2 is a sectional view of an essential part for explaining another embodiment of the inter-cell connection method of the present invention.

FIG. 3 is a cross-sectional view of a connection between cells welded by a resistance welding method according to the present invention.

FIG. 4 is a cross-sectional view of a connection between cells welded by a conventional resistance welding method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Partition wall 2 Through-hole 3 Strap 4 Strap 5 Connection plate 6 Connection plate 7 Welding electrode 8 Welding electrode 9 First projection 10 Second projection 11 Insulator 12 Melted part

Claims (1)

[Claims] 1. A battery case having a plurality of partitioned cells,
A through hole is provided in a partition partitioning each cell, connecting plates extending from the electrode plate group strap of an adjacent cell are arranged on both sides of the through hole, and both connecting plates are pressed by a pair of welding electrodes having projections. , Deformed and press-fitted into the through-holes, while applying current to the welding electrodes for resistance welding, and
In the inter-cell connection method for a storage battery, in which the periphery of the weld is pressurized and the connection plate is brought into close contact with the partition partitioning the cells, the welding electrode has a smooth surface having a smooth surface larger than the diameter of the through hole of the partition of the battery case. And a pair of first projections provided on the first projection and having a second projection for welding whose upper end has a diameter smaller than the diameter of the through hole. At least one of the electrodes limits the electrical conduction between the welding electrode and the connection plate at the time of resistance welding to only the portion of the second protrusion.