JP2000357503A - Intercell connecting method of lead-acid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure liquid tightness between a connected part and a separator and to suppress generation of pores and cracks within the connected part by pushing out and butting connecting bodies faced on the opposite sides of a through hole installed in the separator and supplying power after pressing force is reduced. SOLUTION: A through hole 1a corresponding to lead-alloy connecting bodies 2, 2' for connecting cells is installed in an intercell separator 1. The connecting bodies 2, 2' are pressed with pressing and power supplying electrodes 3, 3' by a first pressing force, and are pushed out into the through hole 1a to be abutted against each other. After that, pressing force is reduced to a second pressing force lower than the first pressing force, the connecting bodies 2, 2' are pressed again by a third pressing force lower than the first pressing force and higher than the second pressing force. In the state of keeping the third pressing force, power is supplied across the connecting bodies 2, 2', the connecting bodies 2, 2' are heated by contact resistance between them and welded. Pressing force is increased while a welded part 4 is melted to a fourth pressing force, and the welding part 4 is cooled and solidified to obtain an intercell connecting part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Various methods have been proposed as methods for connecting cells of a lead storage battery. Generally, in a lead-acid battery for starting a vehicle, a through hole is provided in a partition partitioning between cells, and connection between cells is performed through the through hole. And resistance welding is used as a connection method. In this method, the cell-to-cell connectors made of lead alloy face each other on both sides of the through hole provided in the partition wall, and the cell-to-cell connectors are extruded and deformed with a certain pressing force to come into contact with each other. This is a method of welding the interconnecting members.

[0003] Unlike resistance welding between ordinary plate materials, in the case of resistance welding between cells of a lead-acid battery, it is necessary to perform welding through a through hole provided in a partition wall between connection bodies which are members to be welded. Therefore, it is necessary that the inter-cell connectors are extruded and deformed in accordance with the thickness of the partition wall so that the inter-cell connectors are brought into contact with each other. Also,
Since it is necessary to ensure sufficient liquid tightness between the inter-cell connector and the partition wall after welding in order to ensure the performance as a battery, various resistance welding methods have been particularly proposed.

Among them, Japanese Unexamined Patent Publication (Kokai) No. 2-121257 discloses that the inter-cell connectors are brought into contact with each other by a primary pressing force, current is supplied while maintaining substantially the same pressure, and the welded portion at the end of the current application or immediately after the current application is not yet obtained. It describes that the welded portion is pressurized with a secondary pressing force higher than the primary pressing force at a timing when it is not solidified to be solidified. According to this method, the through hole can be filled with molten lead by secondary pressurization, bubbles and the like in the molten lead can be removed, and the connection body and the partition wall around the through hole can be brought into close contact with each other. The liquid-tightness of the contact portion between the partition wall around the through hole and the weld portion, which is suitable for the connection between cells, is ensured, and a weld portion without defects such as pores and cracks in the weld portion can be obtained.

[0005]

The method of connecting cells of a lead-acid battery having such a pressurized and energized pattern is suitable for a relatively small starting lead-acid battery. Therefore, it is necessary to secure a larger volume of the connection body. In such a case, it is necessary to further increase the pressing force for extruding and butting the opposing connectors through the through holes between the partition walls.

In this regard, US Pat. No. 3,793,086 describes that after the connecting members are pressurized with an initial high pressure and butted in a through-hole, the pressure is reduced and current is applied. This is because, when electricity is supplied while maintaining the initial high pressure, molten lead flows out of the welded portion, and a defect occurs in the connection portion. This U.S. Pat.
According to the technology described in the specification, even when a large connecting body is used, resistance welding can be performed by abutting the connecting bodies.

However, this technique alone cannot completely suppress the outflow of molten lead from the welded portion, and a small amount of outflow of molten lead may occur. In addition, there is a case where the outflow of the molten lead lowers the liquid tightness between the connection portion and the partition wall, or causes a problem that the outflowing molten lead causes a short circuit between the electrode plates.

According to the present invention, there is provided a lead-acid battery between the cells of a lead-acid battery, which opposes both sides of a through hole formed in a partition wall at an initial high pressure as described above, pushes out a connecting body in the direction of each other and abuts each other, and then reduces the pressing force to conduct electricity. In connection body welding, the molten lead is prevented from flowing out from the welded part to ensure liquid tightness between the connection part and the partition wall, and the generation of pores and cracks in the connection part is suppressed, thereby improving the quality of the connection part between cells. The purpose is to:

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a through-hole in which adjacent cells of a lead-acid battery having a monoblock battery case comprising a plurality of cell chambers are provided in partition walls between cells. Inter-cell connection method, wherein the inter-cell connection body is opposed to both sides of the through-hole, and the inter-cell connection body is pressurized with a first pressing force in the through-hole direction, and the inter-cell connection is performed. After butting the bodies in the through hole, the pressure between the inter-cell connectors is reduced to a second pressure lower than the first pressure, and again lower than the first pressure. And a third pressing force higher than the second pressing force, a current is applied between the inter-cell connectors to resistance-weld the inter-cell connectors, and during or immediately after the energization, the inter-cell connectors are connected. The welding force between the welding portions is set as a fourth pressing force higher than the third pressing force. Shows the cell connecting method of the lead-acid battery, characterized in that for cooling and solidification.

According to a second aspect of the present invention, in the configuration of the first aspect, the fourth pressure is at least equal to or greater than the first pressure. It shows an inter-cell connection method.

[0011]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1A is a diagram showing a positional relationship between a connection body and a cell spacing wall at a stage before connection between cells of a lead storage battery. Here, the cell spacing wall 1 is generally a molded body of a polypropylene resin or the like, and through holes 1a are provided corresponding to lead alloy connecting bodies 2 and 2 'for connecting the cells. Next, as shown in FIG. 1B, the connecting bodies 2 and 2 'are pressed by the pressurizing / energizing electrodes 3 and 3' with the first pressing force (P1) and extruded into the through-hole 1a. Match.

Then, after the pressure is reduced from the first pressure (P1) to the second pressure (P2), the pressure is increased again and the pressure is increased by the third pressure (P3). While maintaining the third pressing force (P3), a current is supplied between the connectors 2 and 2 'as shown in FIG.
Heat is generated by the contact resistance therebetween, and the connectors 2, 2 'are welded to each other. The pressing force is increased from the third pressing force to the fourth pressing force at the end of the current application or immediately after the current application and when the welded portion 4 is in a molten state, and is cooled and solidified to obtain an intercell connection portion.

Here, the first pressing force (P1) is necessary for extruding and deforming a relatively large inter-cell connector, and is a prerequisite in the present invention. However, when the pressure during energization is the first pressure (P1), since the molten lead flows out of the welded portion due to high pressure, the pressure during energization is lower than the first pressure (P1). Need to be reduced. An essential part of the present invention is in the process of reducing the first pressure to the pressure at the time of energization.

That is, the above-mentioned US Pat.
As in the technology described in the specification of Japanese Patent No. 6, the initial pressure is not directly reduced from the initial high pressure (corresponding to the first pressure of the present invention) to the pressure at the time of welding. After the pressure is reduced to the second pressure lower than the welding pressure at the time of welding, the pressure is again increased to a third pressure lower than the first pressure but higher than the second pressure. Welding is performed. The first pressing force presses the periphery of the through hole of the partition wall through the connecting body to compressively deform. This compressive deformation is an elastic deformation that can follow the change of the pressing force, and if the adhesion between the connecting body and the partition wall around the through hole is ensured over the entire circumference of the through hole, no outflow of molten lead or the like occurs.

However, in the process of reducing the pressing force, the adhesion between the connecting body and the partition wall around the through hole may be slightly impaired. Furthermore, since molten lead has a very high specific gravity (about 10.5), even if such a slight decrease in adhesion occurs, molten lead flows out due to the pressure during energization and the weight of the molten lead itself. It is supposed that such a decrease in adhesion between the connection body and the partition wall around the through-hole is because the deformation of the partition wall around the through-hole due to pressurization is not completely elastic deformation, but proceeds partially by plastic deformation. .

That is, when the compressive deformation of the partition wall around the through hole is elastic deformation when the pressing force is reduced,
The compressive deformation of the partition wall is restored according to the decrease in the pressing force, and the adhesion to the connection body is secured. However, when the compressive deformation of the partition wall around the through hole is not an elastic deformation but a plastic deformation, the compressive deformation of the partition wall is not completely restored even by a decrease in the pressing force. It is considered that the adhesion is impaired. Therefore, instead of decreasing the pressing force to make the pressing force at the time of energization, increasing the pressing force to make the pressing force at the time of energizing, it is possible to secure the adhesion between the connector and the partition.

In the present invention, when the pressure is reduced from the first pressure to the second pressure once, a part of the partition wall around the through hole and the connection body is partially damaged and the adhesion is deteriorated. I have. From this point, by increasing the pressing force again to the third pressing force, the adhesion between the partition wall around the through hole and the connector at the start of welding can be secured over the entire circumference around the through hole. is there. Electric current is supplied while maintaining the third pressing force, and a weld is formed. Immediately before the end of the energization or immediately after the end of the energization, when the welded portion is still molten, the pressure between the connected members is increased to a fourth pressure that is larger than the third pressure.

This is an indispensable operation for filling the inside of the through hole with the molten lead, and this operation can also suppress generation of bubbles, cracks, and the like in the welded portion. Here, the fourth pressure is preferably at least equal to or greater than the first pressure. According to such a configuration, it is possible to more reliably ensure the liquid-tightness of the connecting portion of the partition. Also, the second pressing force may be any value as long as it is lower than the third pressing force, and it is of course possible to set the second pressing force to zero.

[0019]

First, as described above, connection between cells of a 55D23 type (JIS D5301) starting lead storage battery was performed by the cell connection method according to the present embodiment. The pressurizing / energizing pattern between the connectors during welding is as shown in FIG. As a comparative example, connection between cells of the same lead-acid battery was performed in the pressurizing / energizing pattern shown in FIGS. 3 (a) and 3 (b). The patterns (A1) and (A2) in which the fourth pressing force (P4) was set to 10 kgf / cm ² similarly to the first pressing force (P1) in the pressing / energizing pattern shown in FIG. Pressing force (P
4) is set to 12 kgf /, which is larger than the first pressure (P1).
The pattern (A3) with cm ² is a more preferred embodiment.

Another embodiment is a pattern (A4) in which the fourth pressure (P4) is set to 8 kgf / cm ² which is smaller than the first pressure (P1). In the embodiment of the present invention, the first pressure (P1) is set to 10 kgf / cm ² ,
Is 1 kgf / cm ² for the patterns (A1), (A3) and (A4), and 0 for the pattern (A2), that is, 0 kgf / cm ² .
cm ² . The pressing force at the time of energization, that is, the third pressing force (P3) was set to 5 kgf / cm ² .

The pressing / energizing pattern of Comparative Example 1 (B) shown in FIG. 3A is the first pressing force (P1) in (A1) which is the pressing / energizing pattern of the present embodiment. To the second pressure (P2) and the third pressure from the second pressure (P2).
The step of shifting to the pressing force (P3) is excluded. The pressing and energizing pattern of Comparative Example 2 (C) shown in FIG. 3B is the same as that of Comparative Example 1 shown in FIG. 3A except that the step of increasing the pressing force immediately after the energization is completed. It is. With respect to the inter-cell connection portion according to the present example and the comparative example, the occurrence rate of molten lead ejection, the generation rate of bubbles inside the welded portion, and the liquid tightness of the partition wall at the inter-cell connection portion were evaluated.

As a method for evaluating the liquid tightness, the cell chambers on both sides of the partition are filled with a dilute sulfuric acid electrolytic solution at the connection portion between the cells or more, one of the cell chambers is set to the atmospheric pressure, and the internal pressure of the other cell chamber is set to the atmospheric pressure. The pressure was increased to +100 mmHg and atmospheric pressure +300 mmHg, and a change in the internal pressure of the pressurized cell chamber was confirmed. When the internal pressure of the pressurized cell chamber decreases, it indicates that the liquid tightness is impaired. Table 1 shows the results of these evaluations.

[0023]

[Table 1]

From the results shown in Table 1, according to the inter-cell connection method of the present embodiment, the outflow of molten lead during welding, bubbles and cracks inside the welded portion, and the liquid tightness between the partition walls at the welded portion of the connection body are ensured. You can see that it is. Among them, the inter-cell connection portions (pressing / energization patterns A1, A2, and A3) according to the particularly preferred embodiment of the present invention are compared with the inter-cell connection portions (pressing / energization pattern A4) according to other embodiments of the present invention. It can be seen that it has particularly excellent liquid tightness.

[0025]

According to the present invention, the flow of molten lead at the time of welding is suppressed at the connection part between the cells of the lead storage battery, the liquid tightness with the partition wall is excellent, and the reliability is free from bubbles and cracks inside the welded part. The cell-to-cell connection part having a high density can be obtained, which is extremely effective industrially.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing an inter-cell connection portion according to the present invention.

FIG. 2 is a diagram showing a pressurizing / energizing pattern in the inter-cell connection method of the present invention.

FIG. 3 is a diagram showing a pressurizing / energizing pattern in an inter-cell connection method of a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Partition wall 1a Through-hole 2, 2 'Connection 3, 3' Electrode for pressurization and electricity supply 4 Welded part

Claims (2)

[Claims] 1. An inter-cell connection method for connecting adjacent cells of a lead storage battery having a monoblock battery case comprising a plurality of cell chambers through through holes provided in partition walls between cells.
After facing the inter-cell connector on both sides of the through-hole, pressurizing the inter-cell connector with a first pressing force in the through-hole direction, and butting the inter-cell connectors in the through-hole, A second pressure lower than the first pressing force between the inter-cell connectors.
The pressure is reduced again to a third pressure lower than the first pressure and higher than the second pressure, and a current is supplied between the inter-cell connectors to form a third pressure. Resistance welding during or immediately after the end of energization, and setting the applied pressure between the inter-cell connectors as a fourth applied pressure higher than the third applied pressure, thereby cooling and solidifying the welded portion. Connection method between cells of a lead storage battery. 2. The method according to claim 1, wherein the fourth pressure is at least equal to or greater than the first pressure.