JP2008204772A - Lead-acid storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lead-acid storage battery preventing deterioration of airtightness and liquid tightness between an intercellular connection part and a barrier rib and liquid leakage between cells. <P>SOLUTION: The thickness of the barrier rib 6 in the surroundings of a through hole 6a is made an identical thickness or 0.001 or less in taper amount. Thereby, the pressure between the connection body and the barrier rib becomes uniform at resistance welding, and thus airtightness and liquid tightness of the intercellular connection part is improved. Thereby, in the lead-acid storage battery 17 in which the electrolytic liquid surface 15 is at more than the height of the through hole, the liquid leakage between cells is suppressed, and deterioration of residual capacity by leakage current caused by this, variations in cell volume due to variations in the electrolytic liquid surface, and leakage of the electrolytic liquid can be prevented. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lead-acid battery.

  Lead storage batteries, particularly lead storage batteries for start-up, have a group of electrodes composed of a positive electrode, a negative electrode, and a separator stored in a cell chamber defined by partition walls in a battery case, and are stored between adjacent cell chambers. The mainstream is a structure in which resistance welding is performed through a connection body formed by forming a group of electrode plates.

  In the resistance welding process, as shown in FIG. 1A, the connection body 2 is arranged to face each other through the through hole 1 a provided in the partition wall 1. Next, as shown in FIG. 1 (b), the connecting bodies 2 are brought into pressure contact with each other with the welding electrodes 3, and a welding current is passed through the welding electrodes 3 in this state, whereby contact between the connecting bodies 2 occurs. Generate Joule heat on the surface.

  A part of the connection body 2 is melted by the Joule heat, and the molten lead generated thereby fills the inside of the through hole 1a. Then, the energization is stopped and the molten lead is solidified. When the molten lead is solidified, the pressure contact of the welding electrode 3 to the connection body 2 is released, and resistance welding between the cells is completed as shown in FIG. 1 (c) (see, for example, Patent Document 1).

On the other hand, the battery case is obtained by injection molding a thermoplastic resin such as polypropylene resin, a copolymer of polypropylene resin and polyethylene resin, ABS resin or PPO resin. Generally, a taper is provided so that the thickness of the partition wall gradually decreases from the lower part to the upper part. Therefore, the upper part and the lower part of the through-hole are thicker in the lower part than the upper part, resulting in a difference in thickness.
JP 2006-24451 A

  In the resistance welding process between the cells as described above, it is preferable that the edge portion 1b of the through hole 1a and the connection body 2 are uniformly pressed over the entire circumference of the edge portion 1b. Since the thicknesses of the two are different, the degree of pressure contact with the connection body 2 varies above and below the edge portion 1b.

  Further, a so-called medium dust defect occurs in which molten lead generated during welding scatters from a portion where the degree of close contact between the edge portion 1b and the connection body 2 is low. In the middle dust defect, since a hole is generated in the welded portion, the welding strength is reduced, and the scattered molten lead falls to the electrode plate group, causing a short circuit between the positive electrode plate and the negative electrode plate.

  At the same time, if there is a portion where the degree of close contact between the edge portion 1b and the connection body 2 is low at the end of welding, the airtightness and liquid tightness of the intercell connection portion may be impaired. In addition, the battery case made of polypropylene resin tends to bend in the partition when the battery is used in a high temperature atmosphere, and particularly the adhesion between the edge portion 1b and the connection body 2 is lowered, and the inter-cell connection portion and the partition wall It was easy to generate a gap between them. A so-called liquid leak occurs such that the electrolyte in the cell chamber moves to an adjacent cell through such a gap.

  Due to a liquid leak through the inter-cell connection part, the positive electrode plate of one cell and the negative electrode plate of the other cell of two adjacent cells constitute a cell, and these positive electrode plate and negative electrode plate are Since the cells are electrically connected by the connection between the cells, a leak current is generated between the electrode plates, and the battery capacity is reduced.

  In particular, in a battery in which a valve is arranged in the cell chamber, the cell internal pressure varies due to variations in the valve opening pressure. When an internal pressure difference occurs between adjacent cells, there has been a problem that electrolyte solution movement from a cell having a high internal pressure to a cell having a low internal pressure is promoted, and an abnormal increase in the electrolyte surface is observed.

  The present invention relates to a lead-acid battery in which two electrode plate groups are connected by resistance welding through a through-hole provided in a partition wall, thereby improving the liquid tightness between the connection portion between the cells and the partition wall, thereby providing a liquid junction between the cells. It provides a lead storage battery with excellent reliability.

  In order to solve the above-described problem, an invention according to claim 1 of the present invention includes a battery case partitioned into a plurality of cell chambers by a partition wall, wherein an electrode plate group is accommodated in the cell chamber, and the partition wall is A lead storage battery that is resistance-welded between the electrode plate groups adjacent to each other through a through-hole provided in the partition wall with a connector provided in the electrode plate group, and the electrolyte surface stored in the cell chamber is The partition wall is at least high enough to reach the through-hole, and the partition wall is tapered so that its thickness gradually decreases from the bottom to the opening of the battery case, and around the through-hole of the partition wall. And the lead acid battery which formed the thickness of the site | part which opposes the said connection body uniformly is shown.

  According to a second aspect of the present invention, in the lead acid battery of the first aspect, the electrolyte surface accommodated in the cell chamber is at a height at least reaching the through-hole, and according to the internal pressure of the cell chamber. The lead acid battery provided with the valve which opens and closes is shown.

  ADVANTAGE OF THE INVENTION According to this invention, in the lead storage battery which connects between cells by resistance welding through the through-hole provided in the partition which divides a cell chamber, the liquid-tightness of the connection part between cells can be improved notably.

  Hereinafter, the structure of the lead acid battery by embodiment of this invention is demonstrated using drawing. FIG. 2 is a view showing a cross section of the lead storage battery 4 of the present invention. The lead storage battery 4 has a battery case 5 made of polypropylene resin or the like. The interior of the battery case 5 is partitioned into a plurality of cell chambers 7 by partition walls 6.

  The battery case 5 is closed with a lid 14. Although not shown in FIG. 2, the lid 14 is provided with a structure for discharging the gas staying in the cell chamber 7 such as an exhaust plug to the outside of the battery.

  An electrode plate group 9 provided with a connection body 8 for each of a plurality of cell chambers 7 is accommodated. In the electrode plate group 9, a positive electrode plate 10 and a negative electrode plate 11 are laminated via a separator 12, and electrode plates of the same polarity are connected by a strap 13. The connection body 8 is erected from the strap 13 and resistance-welded through a through-hole 6a provided in the partition wall 6 to form a connection part between cells. 2 and FIG. 4 to be described later show a state in which the resistance welding is completed in which the through hole 6a is filled with molten lead generated from the connection body 8. FIG.

  FIG. 3 is a diagram showing the partition 6 in the lead storage battery 4 of the present invention. In the lead storage battery 4 of the present invention, a taper is provided so that the thickness of the partition wall 6 gradually decreases from the bottom of the battery case 5 to the opening. This taper is provided to ensure the releasability of the battery case 5 when the battery case 5 is resin-molded.

  When the releasability is not sufficiently ensured, the partition wall 6 is deformed when the battery case 5 is die-cut. The necessary taper is greatly influenced by the depth and area of the partition wall 6, but at least 0.002 or more is necessary.

  In the present invention, the electrolytic solution surface 15 is applied to a battery positioned at least above the lower end of the through hole 6a.

  In the present invention, as shown in FIG. 3, a region A is formed in which the thickness of the portion of the partition wall 6 in contact with the connection body 8 is the same. In FIG. 3, a region A formed around the through hole 6a is shown as a hatched portion.

  By providing the region A having the same thickness at the portion around the through-hole 6a where the partition wall 6 and the connection body 8 are in contact, the connection body 8 is in contact with the partition wall 6 in the region A in parallel. Therefore, when resistance welding of the connection bodies 8 is performed, the connection body 8 contacts the edge portion 6b with a uniform pressure over the entire circumference of the edge portion 6b. As a result, it is possible to suppress the scattering of molten lead during resistance welding (medium dust failure) and the decrease in welding strength due to this. Moreover, the airtightness and liquid tightness between the connection body 8 and the partition 6 can be remarkably improved, and liquid leakage between the cell chambers can be suppressed.

  In the region A, the thickness is uniform and the taper is 0, but the taper of 0.001 or less that does not cause a large variation in the contact degree between the connection body 8 and the edge portion 6b is used in the present invention. The partition wall 6 thickness in the region A can be treated as substantially uniform, that is, the taper is zero.

  In addition, the taper value shown in the present embodiment is for one side of the partition wall, for example, when the partition wall thickness reduction at the partition wall height h is Δt, and even taper is provided on both surfaces of the partition wall, The taper amount on one side can be obtained by 0.5 × Δt / h. In addition, when the taper provided in the partition 6 is made uneven on both the left and right side surfaces, the resistance related to the partition 6 becomes uneven on the left and right at the time of die cutting, so that the partition 6 is deformed. Therefore, the taper of the partition wall 6 should be provided equally on the left and right side surfaces.

  In the present invention, since the region A around the through hole 6a of the partition wall 6 is not tapered, if the area of the region A is increased beyond a certain range, the releasability of the battery case 5 may be deteriorated. . Therefore, when the dimension along the die cutting direction of the region A is a and the dimension along the direction perpendicular to the die cutting direction of the region A is b, b / a is 0.3 or more and a is 70 mm or less. It is preferable that The formation of the region A to this extent does not significantly affect the releasability of the battery case 5, and the deformation of the partition wall 6 at the time of release is also suppressed.

  The configuration of the present invention described above is preferably applied to a lead storage battery in which the thickness of the thinnest portion excluding the region A of the partition wall 6 is 3.0 mm or less. When the partition wall 6 has a thickness of 3.0 mm or less, particularly less than 1.5 mm, the partition wall 6 is easily deformed by heat in applications where the partition wall 6 is used at a high temperature (40 to 80 ° C.) such as a lead storage battery for starting. As a result, a minute gap is likely to be generated between the connection body 8 and the partition wall 6, and the airtightness and liquid tightness at this portion are reduced.

  In this invention, even if it is a lead storage battery with such a thin partition, it can weld between electrode board groups without a gap with the stable welding strength.

  As described above, according to the present invention, in the lead storage battery in which the connection bodies adjacent to each other through the through-hole provided in the partition wall are resistance welded, the liquid tightness between the partition wall and the connection portion between the cells is remarkable. As a result, it is possible to suppress liquid leakage through a minute gap between the inter-cell connection portion and the through hole, which has been conventionally generated.

  The present invention is an open-liquid type lead-acid battery, and can suppress a liquid leak that occurs in a lead-acid battery having a structure in which an inter-cell connection portion is immersed in an electrolytic solution. In particular, the cell chamber as shown in FIG. It is particularly suitable for a lead storage battery 17 having a valve 16 every 7 and having an electrolyte surface 15 set to be equal to or higher than the lower end of the through hole 6a. In addition, in the lead storage battery which has such an electrolyte solution abundantly, the valve 16 has an effect which suppresses the liquid reduction of an electrolyte solution. Further, when the liquid reduction progresses and the electrode plate is exposed from the electrolyte, the valve 16 operates as a control valve, and the oxidative deterioration of the negative electrode plate due to oxygen in the atmosphere is caused as in the case of the negative electrode absorption control valve type lead storage battery. It is suppressed.

  When the valve 16 is disposed in the cell chamber 7, an internal pressure difference occurs between the cell chambers 7 due to variations in the opening / closing valve pressure of the valve 16. Such an internal pressure difference further promotes liquid leakage through a minute gap between the partition wall 6 and the connection body 8, and is a technical problem of the lead-acid battery 17 with a valve that has abundant electrolyte. there were.

  When there is an internal pressure difference between cells even in a very small gap, which is not a problem with ordinary open-fluid lead-acid batteries and ordinary control valve-type lead-acid batteries that have almost no free electrolyte. There was a liquid leak.

  According to the present invention, since the generation of a minute gap between the connection body 8 and the through hole 6a can be suppressed, the electrolyte surface 15 reaching the through hole 6a and the valve provided for each cell chamber 7 are provided. By applying the configuration of the present invention to the attached lead storage battery 17, liquid leakage between the cell chambers 7 can be remarkably suppressed.

(Example 1)
For the lead-acid battery 4 of the present invention shown in FIG. 2, as shown in Table 1, batteries were produced in which the taper of the partition wall 6 and the taper of the region A arranged around the through hole 6a were variously changed. Further, in the cell chambers 7 adjacent to each other, the electrolyte solution was alternately injected to make it easy to confirm the movement of the electrolyte solution between the cell chambers 7.

  In each test battery, the height dimension h from the lowermost portion excluding the uppermost heat-welded portion of the partition wall 6 is 175 mm. Furthermore, the diameter of the through hole 6a is 11.0 mm. In the area A, the a dimension along the die cutting direction in FIG. 3 was 50 mm, and the b dimension along the direction orthogonal to the die cutting direction was 20 mm.

  Further, the taper of the partition wall 6 is provided uniformly over the both sides in the same amount and in the height direction with the center line in the thickness direction of the partition wall 6 being vertical. The taper of the partition wall 6 is uniformly formed in a portion excluding a portion where the thickness is changed by a heat-welded portion between the bottom of the cell chamber 7 and the lid at the tip of the partition wall 6. The taper amount of the partition wall shown in Table 1 is shown on one side of the partition wall 6, and is an amount given by 0.5 × (thickness of the bottom of the partition wall−thickness of the top of the partition wall) / (partition wall height). .

  The taper of the region A is given by 0.5 × (partition wall thickness at the lower end of the region A−partition wall thickness excluding the heat welded portion at the upper end of the region A) / (height excluding the heat welded portion of the region A). In addition, when the taper of the partition wall 6 is 0.001, the partition wall 6 is deformed at the time of molding the battery case due to a decrease in releasability, and is not suitable as a lead-acid battery battery case. The lower limit of the taper amount of 6 was set to 0.002.

  Further, the pressure applied between the connected bodies during resistance welding was set to 0.9 MPa.

  The cell chamber 7 in which the electrolyte solution is not injected in the two cell chambers 7 adjacent to each other via the partition wall is opened to the atmosphere, and the internal pressure of the cell chamber 7 into which the electrolyte solution is injected is 10.0 kPa from atmospheric pressure. The cell chamber was closed as it was raised to a maximum. In addition, 45 wt% dilute sulfuric acid was used as the electrolytic solution. In addition, the electrolyte surface 15 at this time was set to the upper end height of the through hole 6a.

  In this state, each battery was left for 24 hours, and the internal pressure after being left for 24 hours was measured. In addition, the presence or absence of electrolyte leakage through the inter-cell connecting portion to the cell chamber 7 having the same pressure as the atmospheric pressure was confirmed from the cell chamber 7 in which the cell chamber was raised from the atmospheric pressure. When a liquid leak occurs, the leaked electrolyte is collected in the cell chamber having the same pressure as the atmospheric pressure. Therefore, the presence or absence of the liquid leak can be confirmed by the presence or absence of the electrolyte in the cell chamber. These results are also shown in Table 1.

  From the results shown in Table 1, the batteries 1 to 3, the batteries 6 to 8, and the batteries 12 to 12 in which the region A having a taper amount in the range of 0 to 0.001 is formed around the through hole 6a for resistance welding of the partition wall 6 are formed. In No. 14, liquid leakage from the cell chamber side where the internal pressure was increased to the cell chamber side where the internal pressure was atmospheric pressure was suppressed. At the same time, there was no change in the internal pressure of the cell chamber having the higher internal pressure.

  On the other hand, for the batteries 4 to 5, the batteries 9 to 10, and the batteries 15 to 17 in which the taper amount in the area A is 0.002 or more, liquid leakage occurs and at the same time, the cell chamber is set at a high atmospheric pressure. There was a drop in pressure. In particular, in the battery 5, the battery 10, and the batteries 16 to 17 having taper amounts of 0.01 and 0.005, the electrolytic solution surface 15 was lowered to the lower end of the through hole 6a. In Example 1, since the initial position of the electrolytic solution surface 15 is the upper end of the through hole, the amount of the electrolytic solution corresponding to the liquid level difference corresponding to the diameter (11.0 mm) of the through hole 6a moves to the adjacent cell. That's true.

  In such a case, the difference in the amount of electrolyte between the cells affects the battery performance, for example, the battery capacity, and causes a variation in cell capacity within the series cells. As a result, since the cell with the smallest capacity is always overdischarged, the charge / discharge life is extremely shortened. In addition, the cell in which the electrolytic solution surface 15 is raised by the electrolytic solution movement causes the electrolytic solution to leak from the valve 16. Furthermore, since the liquid leaks between the cells, the leakage current always flows through the connection part between the cells, although it is a low current of about several tens to several mA, so that the battery capacity decreases when the battery is left for a long time. Become.

  In these batteries in which the taper amount of the region A is larger than 0.002, the airtightness and liquid tightness between the inter-cell connecting portion and the through hole 6 are lowered, and the liquid leak occurs. . For these batteries, when the applied pressure applied between the connecting bodies during resistance welding is further increased from 0.9 MPa, the adhesion between the inter-cell connecting portion and the through-hole is improved, but the applied pressure is reduced. In the case of further increase, for example, about 1.2 MPa, molten lead generated during resistance welding leaks from the contact surface between the partition wall and the connection body, and a medium dust defect is likely to occur. In such a case, the medium dust defect rate increases rapidly for those that did not have medium dust defects, although the airtightness between the partition walls and the inter-cell connection portions is maintained. Therefore, it is not appropriate to increase the pressure.

  Regarding the batteries 1 to 3, the batteries 6 to 8, and the batteries 12 to 14 in which the taper amount in the region A is 0.001 or less, the internal pressure in the cell chamber is kept constant, and no liquid leak occurs. As a result, it can be seen that very good airtightness and liquid tightness are maintained between the inter-cell connecting portion and the partition wall. Moreover, since the pressurizing force between the connection bodies of resistance welding is not increased, it is possible to suppress the occurrence of middle dust defects.

  In the present embodiment, in the lead storage battery 17 in which the electrolyte surface is set up to the height of the through hole 6a provided in the partition wall 6 for inter-cell connection, and the valve 16 is provided in the cell chamber 7, the valve 16 It is assumed that the internal pressure difference in the cell chamber 7 is 10 kPa due to pressure variations. From the present embodiment, in the lead storage battery 17 which is set to be equal to or higher than the lower end height of the through hole 6a provided in the partition wall 6 for connection between cells and in which the valve 16 is provided in the cell chamber 7, the connection portion between the cells and the partition wall It can be seen that the airtightness and liquid tightness of No. 6 are improved, and liquid leakage between the cell chambers 7 can be suppressed.

(Example 2)
In Example 2, an experiment was performed in which the internal pressure of the cell chamber 7 was all atmospheric pressure in Example 1. A test battery was prepared by newly preparing each battery of Example 1. As in Example 1, two cell chambers 7 adjacent to each other are taken as a set, and electrolyte is injected into one cell chamber 7 of the set up to the position of the upper end of the through hole 6a. The electrolyte was not injected. In this state, the battery was allowed to stand at 25 ° C. for 1 month, and the liquid leakage state after 24 hours and 1 month after the start of the storage was confirmed. The results are shown in Table 2.

  From the results shown in Table 2, liquid leakage did not occur in all the batteries when the standing time was 24 hours. In the case where the standing time was one month, in Example 1, the batteries 4 to 5, the batteries 9 to 10, and the batteries 15 to 17 in which the liquid leak occurred were leaked. However, in Example 1, a large amount of liquid leak was observed in which the electrolyte surface level 15 decreased by 11.0 mm. However, the liquid leak generated in Example 2 was caused by the fact that the electrolyte solution was dropped on the surface of the connection body 8. The amount of liquid leakage was such that it became attached.

  With the liquid leak of the level observed in Example 2, the electrolyte surface 15 hardly changes. Therefore, there is no problem such as cell capacity variation or overflow due to variation of the electrolyte surface 15. However, although a small amount of liquid leaks between two adjacent cell chambers 7, a leakage current flows through the inter-cell connection portion, and the remaining capacity is reduced by being left for a long time.

  On the other hand, in the present invention, no liquid leak was observed even after standing for one month, and the airtightness and liquid tightness between the inter-cell connection portion and the partition wall 6 were remarkably improved. As a result, it is possible to avoid characteristic deterioration such as a decrease in remaining capacity due to leakage current.

  As described above, from the results shown in Example 1 and Example 2, according to the present invention, the electrode plate groups accommodated in the cell chambers adjacent to each other through the through holes 6a provided in the partition wall 6 are resistance-welded. In lead-acid batteries having connected inter-cell connecting portions and the electrolyte surface 15 set to a height higher than the lower end of the through-hole 6a, the airtightness and liquid-tightness between the inter-cell connecting portions and the partition walls are improved. As a result, liquid leakage between the cell chambers is remarkably suppressed. Therefore, since leakage current due to liquid leakage is suppressed, it is possible to suppress a decrease in remaining capacity when the battery is left for a long time.

  In particular, in the lead storage battery 17 in which the valve 16 is provided in the cell chamber 7 for the purpose of suppressing liquid reduction or for promoting the oxygen gas absorption reaction at the negative electrode, the opening / closing valve pressure of the valve 16 is reduced in addition to the above effect. Even with the variation, the electrolyte solution movement between the cells is suppressed, so that there is a remarkable effect that the variation in the amount of the electrolyte solution between the cells is suppressed. By such an effect, it is possible to prevent problems such as battery capacity variations due to electrolyte amount variations and electrolyte overflow.

  The present invention remarkably improves the airtightness and liquid-tightness between the connection part between the cells and the partition wall in the lead storage battery composed of a plurality of cells, and various types such as a lead storage battery for starting and a lead storage battery for electric vehicles. It is suitable for lead-acid batteries.

(A) The figure which shows the resistance welding process between cells (b) The other figure which shows the resistance welding process between cells (c) The figure which shows the state which the resistance welding between cells was completed The figure which shows the cross section of the lead acid battery of this invention The figure which shows the partition of the lead acid battery of this invention The figure which shows the cross section of the other lead acid battery of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Partition 1a Through-hole 1b Edge part 2 Connection body 3 Welding electrode 4 Lead storage battery 5 Battery case 6 Partition 6a Through-hole 6b Edge part 7 Cell chamber 8 Connection body 9 Electrode plate group 10 Positive electrode 11 Negative electrode 12 Separator 13 Strap 14 Lid 15 Electrolyte level 16 Valve 17 Lead acid battery A area

Claims (2)

Connection having a battery case partitioned into a plurality of cell chambers by a partition wall, the electrode plate group being housed in the cell chamber, and the electrode plate group adjacent to each other via the partition wall provided in the electrode plate group A lead-acid battery that is resistance-welded through a through-hole provided in the partition wall in a body, the electrolyte surface stored in the cell chamber is at least at a height that reaches the through-hole, and the partition wall of the battery case A lead-acid battery in which a taper is provided so that the thickness thereof gradually decreases from the bottom to the opening, and the thickness of a portion of the partition that is around the through-hole and that faces the connection body is uniformly formed. The lead acid battery of Claim 1 provided with the valve opened and closed according to the internal pressure of the said cell chamber.

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