lead-acid batteries

Abstract

To provide a lead storage battery capable of reducing a generation of a gap between a lid part and a terminal.SOLUTION: A lead storage battery 1 comprises a case 7 having a lid part 9 formed in a rectangular form as well as inserting each of a positive electrode terminal 5A and a negative electrode terminal 5B. In an inner surface 32 of the lid part 9, a first rib 51 and a second rib 52 are formed. When it passes through each of the positive electrode terminal 5A and the negative electrode terminal 5B, and a pair of straight lines parallel to first sides 91 and 91 of the lid part 9 is first virtual straight lines VL1 and VL1, an arrangement density of the rib in a first region A1 as a region of the inner surface 32 nipped by the pair of first virtual straight lines VL1 and VL1 in a direction where a second side 92 of the lid part 9 is extended is higher than that of the rib in a pair of second regions A2 and A2 as a region of the inner surface 32 that nips the first region A1 in a long side direction of the lid part 9.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] One aspect of the present invention relates to a lead-acid battery.

Background Art

[0002] As one of the secondary batteries that have been conventionally used, lead-acid batteries are widely known. Lead-acid batteries are widely used as industrial or consumer secondary batteries due to their reliability, low cost, etc. In particular, there is a high demand for lead-acid batteries for automobiles (so-called batteries), or for backup such as UPS (Uninterruptible Power Supply), disaster prevention (emergency) radios, and telephones. Patent Document 1 discloses a lead-acid battery including a laminate (electrode group) composed of a plurality of positive electrode plates, a plurality of negative electrode plates, and a plurality of separators, and a case composed of a bottomed cylindrical main body that encloses these and a lid portion that covers an opening of the main body.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such a lead-acid battery, the pressure in the internal space sealed by the battery case and the lid portion fluctuates with charging and discharging, and the battery case and the lid portion may be deformed. In particular, when the lid portion is deformed, a gap may occur between the lid portion and the terminals (positive electrode terminal and negative electrode terminal) that are attached in close contact with each other, and for example, there is a risk that problems such as leakage of the electrolyte from the gap may occur.

[0005] Therefore, an object of one aspect of the present invention is to provide a lead-acid battery capable of reducing the occurrence of a gap between the lid portion and the terminals.

Means for Solving the Problems

[0006] A lead-acid battery according to one aspect of the present invention is a lead-acid battery comprising a case having a rectangular lid through which positive and negative terminals are inserted, wherein ribs are formed on the inner surface of the lid, and when a pair of straight lines passing through the positive and negative terminals and parallel to the short side of the lid are defined as first virtual straight lines, the arrangement density of ribs in the first region, which is the inner surface region sandwiched between the pair of first virtual straight lines in the direction in which the long side of the lid extends, is higher than the arrangement density of ribs in the pair of second regions, which are the inner surface regions sandwiching the first region in the direction of the long side of the lid.

[0007] In a lead-acid battery in which the positive and negative terminals are inserted through the lid, deformation of the lid could cause the electrolyte to seep up and leak out from between the positive and negative terminals and the lid. The inventors of the present invention have conducted thorough research and found that the electrolyte does not leak uniformly from the entire circumference of the positive and negative terminals, but is concentrated on specific parts of the circumferential surface of the positive and negative terminals. More specifically, they found that deformation is likely to occur in the inner circumferential surface portion of the positive and negative terminals where the positive and negative terminals face each other (hereinafter also referred to as the "target portion"), and that this deformation causes the electrolyte to leak.

[0008] Therefore, in a lead-acid battery according to one aspect of the present invention, ribs are arranged on the inner surface of the lid, and the density of ribs in the first region adjacent to the target portion is higher than in other regions (second region). That is, the first region is provided in the area sandwiched by the pair of first virtual straight lines mentioned above, and the second region is provided so as to sandwich the first region. This improves the strength of the lid adjacent to the target portion and suppresses deformation that occurs in the target portion. As a result, the occurrence of gaps between the lid and the terminals can be reduced.

[0009] In a lead-acid battery according to one aspect of the present invention, the ratio of the rib arrangement area per unit area in the first region may be 5% or more. With this configuration, deformation of the lid in the first region can be suppressed more reliably.

[0010] A lead-acid battery according to one aspect of the present invention may have a rated capacity of 1000 Ah or more. In this configuration, even with a lead-acid battery having a rated capacity of 1000 Ah or more, the gap between the lid and the terminals can be reduced. [Effects of the Invention]

[0011] According to one aspect of the present invention, it is possible to reduce the gap that occurs between the lid and the terminals. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a schematic exploded perspective view showing a lead-acid battery according to one embodiment. [Figure 2] Figure 2 is a schematic perspective view showing the lid of the lead-acid battery shown in Figure 1. [Figure 3] Figure 3 is a schematic cross-sectional view along the line III-III in Figure 2. [Figure 4] Figure 4 is a plan view of the lid as seen from the side of the storage space. [Modes for carrying out the invention]

[0013] A lead-acid battery 1 according to one embodiment will be described below with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant explanations are omitted.

[0014] As shown in Figure 1, the lead-acid battery 1 is, for example, a valve-regulated lead-acid battery. The lead-acid battery 1 has a rated capacity of 1000 Ah or more. The lead-acid battery 1 in this embodiment has a rated capacity of 1500 Ah. The lead-acid battery 1 comprises an electrode group 3, a positive electrode terminal 5A, a negative electrode terminal 5B, a control valve 6, and a case 7.

[0015] Electrode group 3 is an assembly of multiple electrode plates, comprising multiple positive electrodes 10, multiple negative electrodes 12, and multiple separators 13. In electrode group 3, the positive electrodes 10 and negative electrodes 12 are arranged alternately. Separators 13 are placed between adjacent positive electrodes 10 and negative electrodes 12. Therefore, the positive electrodes 10, separators 13, and negative electrodes 12 overlap sequentially in a predetermined direction. In this embodiment, in electrode group 3, negative electrodes 12 are placed at the ends in the arrangement direction (hereinafter sometimes simply referred to as the "arrangement direction") of the positive electrodes 10, negative electrodes 12, and separators 13. The assembly of positive electrodes 10, negative electrodes 12, and separators 13 is also called a battery electrode group. When electrode group 3 and electrolyte are housed in case 7, the electrolyte exists in the gaps between the positive electrodes 10 and separators 13, inside the separators 13, etc. The above arrangement direction corresponds to the first direction X. Furthermore, in the following, the directions perpendicular to the first direction X will be referred to as the second direction Y and the third direction Z.

[0016] The positive electrode 10 is a positive electrode plate in the lead-acid battery 1 and is electrically connected to the positive electrode terminal 5A. Each positive electrode 10 and the positive electrode terminal 5A are electrically connected by a positive electrode strap 17. Although not shown, the positive electrode 10 includes, for example, a current collector and a positive electrode material. The negative electrode 12 is a negative electrode plate in the lead-acid battery 1 and is electrically connected to the negative electrode terminal 5B. Each negative electrode 12 and the negative electrode terminal 5B are electrically connected by a negative electrode strap 18. The negative electrode 12 includes, for example, a current collector and a negative electrode material. The separator 13 is a battery component for preventing short circuits between the positive electrode 10 and the negative electrode 12. The separator 13 is not particularly limited as long as it electrically insulates the positive electrode 10 and the negative electrode 12 while allowing ions to pass through, and has resistance to oxidation on the positive electrode 10 side and reduction on the negative electrode 12 side. Each separator 13 may have a bag shape and cover the main part of the corresponding negative electrode 12.

[0017] The current collector can be made of any conductive material. Examples of current collector materials include lead alloys such as lead-calcium-tin alloys and lead-antimony-arsenide alloys. The positive electrode material includes, for example, a positive electrode active material after chemical formation. The negative electrode material includes, for example, a negative electrode active material such as spongy lead. Examples of materials for the separator 13 include glass fibers, resins, inorganic materials, etc.

[0018] As shown in Figures 1 to 3, the positive terminal 5A and the negative terminal 5B are terminals for electrically connecting the electrode group 3 to an external device. Each of the positive terminal 5A and the negative terminal 5B has, for example, a first part 5c fixed to the cover 9 and a second part 5d fixed to the first part 5c. The first part 5c is a conductive part containing lead. The first part 5c may be formed with lead as the main component or may be formed from lead alone. The second part 5d is a core part formed from a metal or alloy. The second part 5d is formed from, for example, an alloy of copper and zinc (brass).

[0019] A bushing 22 is formed on a portion of the first part 5c. The bushing 22 is made of a material mainly composed of lead, or a material formed from lead. At the positive terminal 5A and the negative terminal 5B, the bushing 22 is integrated with another portion of the first part 5c by welding. The bushing 22 is a cylindrical member provided on the inner circumferential surface of the first through hole 33, which will be described in detail later. The outer circumferential surface 22a of the bushing 22 is in close contact with the inner circumferential surface 38a of the first cylindrical part (cylindrical part) 38 that forms the first through hole 33. More specifically, the outer circumferential surface 22a of the bushing 22 is in close contact with the inner circumferential surface 38a of the first cylindrical part 38. The outer circumferential surface 22a of the bushing 22 has an uneven surface 22b that fits into the uneven surface 38b formed on the inner circumferential surface 38a of the first cylindrical part 38.

[0020] Case 7 has a main body portion 8 and a lid portion 9 that overlaps the main body portion 8 in the third direction Z (lamination direction). The main body portion 8 is formed in a bottomed cylindrical shape. The main body portion 8 is made of a material such as polypropylene. The main body portion 8 has a storage space S for storing the electrode group 3 and the electrolytic solution. The main body portion 8 is composed of four side portions and a bottom portion. The corners formed by the bottom portion and the side portions are rounded.

[0021] The lid portion 9 is a member that covers the opening of the main body portion 8 and is formed of a material such as polypropylene like the main body portion 8. Note that FIG. 2 shows the lid portion 9 in a state where the control valve 6 is removed. The lid portion 9 has a substantially hat shape when viewed from each of the first direction X and the second direction Y. As shown in FIG. 4, the outer shape of the lid portion 9 when viewed from the third direction Z (the penetration direction of the first cylindrical portion 38) is formed in a rectangular shape composed of a pair of first sides (short sides) 91, 91 that are parallel to each other and a pair of second sides (long sides) 92, 92 that are parallel to each other. In the present embodiment, the size of the first side 91 is smaller than the size of the second side 92. That is, the outer shape of the lid portion 9 when viewed from the third direction Z (the penetration direction of the first cylindrical portion 38) is formed in a rectangular shape.

[0022] As shown in FIGS. 2 to 4, the lid portion 9 has a main portion 21a that covers the opening of the main body portion 8 and an edge portion 21b that surrounds the periphery of the main portion 21a and is located one step below the main portion 21a. The main portion 21a has an outer surface 31 and an inner surface 32 that intersect the third direction Z, two first through holes 33, 33, a second through hole 35, two recesses 36, 36, two first cylindrical portions 38, 38, a second cylindrical portion 40, a first rib 51, and a second rib 52.

[0023] The outer surface 31 corresponds to the surface that is exposed when, for example, the lid 9 is attached to the main body 8, and has a substantially rectangular shape when viewed from a third direction Z. The outer surface 31 constitutes a part of the surface of the case 7. The outer surface 31 is provided with two recesses 36, 36 spaced apart from each other and a second cylindrical portion 40. The inner surface 32 is the surface located on the opposite side of the outer surface 31 in the third direction Z, and corresponds to the surface that is hidden when the lid 9 is attached to the main body 8. The inner surface 32 is provided with two first cylindrical portions 38, 38, a first rib 51, and a second rib 52.

[0024] The first through-hole 33 and the second through-hole 35 are each formed in a circular shape when viewed from the third direction Z, and are openings that extend in the third direction Z. The first through-hole 33 and the second through-hole 35 each penetrate the housing space S and the external space of the case 7. The second through-hole 35 is located between the two first through-holes 33, 33 in the second direction Y. A positive terminal 5A is provided in one of the first through-holes 33, a negative terminal 5B is provided in the other first through-hole 33, and a control valve 6 is provided in the second through-hole 35. The first through-hole 33 communicates with the first cylindrical portion 38, and the second through-hole 35 communicates with the second cylindrical portion 40. For this reason, in the following, the cavity of the first cylindrical portion 38 is considered to be part of the first through-hole 33, and the cavity of the second cylindrical portion 40 is considered to be part of the second through-hole 35. Similarly, the inner circumferential surface 38a of the first cylindrical portion 38 is considered to be part of the inner circumferential surface 33a of the first through hole 33, and the inner circumferential surface 40a of the second cylindrical portion 40 is considered to be part of the inner circumferential surface 35a of the second through hole 35. That is, the lid portion 9 has two first cylindrical portions 38, 38 that penetrate the housing space S and the external space, and into which the positive terminal 5A connected to the positive electrode 10 and the negative terminal 5B connected to the negative electrode 12 are inserted.

[0025] The recess 36 is a depression on the outer surface 31 that surrounds the first through hole 33 when viewed from a third direction Z. In this embodiment, the surface 36a of the recess 36 is formed in an annular shape when viewed from a third direction Z. The recess 36 is provided with a first projection 41 that surrounds the first through hole 33 and the bushing 22 when viewed from a third direction Z, and a second projection 42 that surrounds the first projection 41 when viewed from a third direction Z.

[0026] The first projection 41 is formed in an annular shape when viewed from the third direction Z and is a portion provided within the recess 36. The first projection 41 protrudes from the inner edge of the surface 36a toward the outer surface 31 along the third direction Z. The second projection 42 is formed in an annular shape when viewed from the third direction Z and is a portion provided along the outer edge of the recess 36. The second projection 42 is spaced apart from the first projection 41. Therefore, a groove G is provided between the first projection 41 and the second projection 42 in the recess 36.

[0027] The groove G is filled with a filler 24. The filler 24 is, for example, a cured resin component. The resin constituting the filler 24 is, for example, an ultraviolet curing resin or a thermosetting resin, and includes at least an epoxy resin. The main component of the resin constituting the filler 24 may be a single or multiple types of epoxy resins. The filler 24 may contain various additives, etc.

[0028] The first cylindrical portion 38 is formed in a substantially cylindrical shape when viewed from the third direction Z and extends in the third direction Z. When the lid portion 9 is attached to the main body portion 8, the first cylindrical portion 38 protrudes from the inner surface 32 toward the electrode group 3. The second cylindrical portion 40 is the portion of the lid portion 9 to which the control valve 6 is attached. The second cylindrical portion 40 is formed in a substantially cylindrical shape when viewed from the third direction Z and extends in the third direction Z.

[0029] As shown in Figure 4, a first rib 51 and a second rib 52 are formed on the inner surface 32 of the lid portion 9. The first rib 51 and the second rib 52 are parts that protrude toward the storage space S when the lid portion 9 is attached to the main body portion 8 (see Figure 1), and are provided to improve the rigidity of the lid portion 9. The first rib 51 extends in the direction extending toward the first side 91 (first direction X). The second rib 52 extends in the direction extending toward the second side 92 (second direction Y). In other words, the first rib 51 extends along the short side direction of the lid portion 9, and the second rib 52 extends along the long side direction of the lid portion 9.

[0030] The first rib 51 has a triangular cross-section perpendicular to its direction of extension. The second rib 52 also has a triangular cross-section perpendicular to its direction of extension, similar to the first rib 51. In this embodiment, examples of the cross-sectional shapes of the first rib 51 and the second rib 52 being triangular have been given, but they may also be rectangular, trapezoidal, or semicircular. Furthermore, the cross-sectional shapes of the first rib 51 and the second rib 52 may be triangular, rectangular, or trapezoidal with chamfered corners. The width of the second rib 52 is greater than the width of the first rib 51. The width of the second rib 52 (size in the first direction X) is, for example, 1.0 mm to 6.0 mm, and the width of the first rib 51 (size in the second direction Y) is 1.0 mm to 6.0 mm. Note that the width of the rib referred to here is the size of the largest visible part when viewed from above (for example, the base of the rib).

[0031] The inner surface 32 of the lid portion 9 is provided with a first region A1 and a second region A2, each having a different rib arrangement density (the arrangement density of the first rib 51 and the second rib 52). The rib arrangement density refers to the ratio of the rib arrangement area per unit area (the total area of ​​the first rib 51 and the second rib 52 combined) when viewed from a third direction Z (when viewed from above). Here, when a pair of straight lines parallel to the first side 91 passing through each of the first cylindrical portions 38 (positive terminal 5A and negative terminal 5B) are defined as first virtual straight lines VL1, VL1, the first region A1 is the region on the inner surface 32 of the lid portion 9 sandwiched between the pair of first virtual straight lines VL1, VL1. The second region A2 is the region on the inner surface 32 of the lid portion 9 that is provided in the direction of the long side of the lid portion 9 (the direction of extension of the second side 92) so as to sandwich the first region A1.

[0032] In this embodiment, the arrangement density of ribs in the first region A1 is higher than the arrangement density of ribs in the second region A2. The first rib 51 and the second rib 52 are arranged such that their arrangement density in the first region A1 is 5% or more. However, from the viewpoint of more reliably suppressing the deformation of the lid portion 9 in the first region A1, it is more preferable that the arrangement density of the first rib 51 and the second rib 52 in the first region A1 is 10% or more. The arrangement density of the first rib 51 and the second rib 52 in the first region A1 may be 35% or less.

[0033] The effects of the lead-acid battery 1 of the above embodiment will now be explained. As described above, in the lead-acid battery 1 configured such that the positive electrode terminal 5A and the negative electrode terminal 5B are inserted into the first cylindrical portion 38 formed in the lid portion 9, as shown in Figure 3, there was a risk that the electrolyte would seep up and leak out from between the outer peripheral surface 22a of the positive electrode terminal 5A and the negative electrode terminal 5B (bushing 22) and the inner peripheral surface 38a of the first cylindrical portion 38. Therefore, the inventors of the present invention applied a predetermined load (for example, 18kN) to the entire lid portion 9 and obtained the stress distribution acting on the lid portion 9 at that time. Based on the analysis results of the stress distribution on the inner peripheral surface 38a of the first cylindrical portion 38, the inventors of the present invention found that the stress acting on the inner peripheral surface 38a of the first cylindrical portion 38 was not uniform, and that a specific part was higher. Furthermore, it was found that the part where the electrolyte leaks out is the inner circumferential surface portion P (see Figure 4) of the inner circumferential surface 38a of the first cylindrical portion 38 where the positive electrode terminal 5A and the negative electrode terminal 5B face each other, and that this deformation is the cause of the electrolyte leaking out.

[0034] Therefore, in the lead-acid battery 1 of the above embodiment, as shown in Figure 4, a first rib 51 and a second rib 52 are arranged on the inner surface 32 of the lid portion 9, and the arrangement density of the ribs (first rib 51 and second rib 52) in the first region A1, which is the region in contact with the inner circumferential surface portion P, is higher than that of the second region A2. In other words, in the lead-acid battery 1 of the above embodiment, the first region A1 is provided in the region sandwiched between the pair of first virtual straight lines VL1, VL1 described above, and the second region A2 is provided so as to sandwich the first region A1. This improves the strength of the lid portion 9 in contact with the inner circumferential surface portion P, and suppresses deformation that occurs in the first region A1 where the inner circumferential surface portion P (see Figure 4) is located. As a result, it is possible to reduce the occurrence of gaps between the first cylindrical portion 38 and the positive electrode terminal 5A, and between the first cylindrical portion 38 and the negative electrode terminal 5B, due to deformation of the lid portion 9.

[0035] Although one embodiment has been described above, one aspect of the present invention is not limited to the above embodiment. Various modifications are possible without departing from the spirit of the invention.

[0036] (Variation 1) In the lead-acid battery 1 of the above embodiment, an example was given in which two positive terminals 5A and negative terminals 5B are arranged in total, but the invention is not limited to this. For example, three or more positive terminals 5A and negative terminals 5B may be arranged in total. In the case of the lead-acid battery 1 according to this modified example, a pair of straight lines parallel to the first sides (short sides) 91,91, passing through the first cylindrical parts 38,38 that are closest to each of the pair of first sides 91,91, become a pair of first virtual straight lines VL1,VL1. In the lead-acid battery 1 according to Modified Example 1, the gap between the first cylindrical part 38 in the lid part 9 and the positive terminal 5A (or negative terminal 5B) can be reduced.

[0037] (Modification 2) In the above embodiments and modifications, an example was given in which the first region A1 is set to be a region sandwiched between a pair of first virtual lines VL1, VL1, but the invention is not limited thereto. For example, the first region A1 may be a region sandwiched between a pair of first virtual lines VL1, VL1, and also sandwiched between a pair of second virtual lines. Here, the pair of second virtual lines refers to a pair of lines parallel to the second sides 92, 92 that pass through the first cylindrical parts 38, 38 that are closest to each of the second sides 92, 92. That is, in the lead-acid battery 1 according to modification 2, the first region A1, in which the arrangement density of ribs (first rib 51 and second rib 52) is higher than that of the second region A2, is provided in a region enclosed by a pair of first virtual lines VL1, VL1 and a pair of second virtual lines, and the second region A2 is provided so as to surround the first region A1.

[0038] In the lead-acid battery 1 according to Modification 2, similar to the above embodiment and modification, the gap between the first cylindrical portion 38 of the lid 9 and the positive terminal 5A (or negative terminal 5B) can be reduced. Furthermore, in the lead-acid battery 1 according to Modification 2, the first region A1 can be defined as the smallest area adjacent to the inner circumferential surface portion P described above. In other words, in the lead-acid battery 1 according to Modification 2, the first region A1 for reducing the gap between the first cylindrical portion 38 of the lid 9 and the positive terminal 5A (or negative terminal 5B) can be made to the minimum necessary area. As a result, the increase in material required to increase the arrangement density of the ribs (first rib 51 and second rib 52) can be kept to a minimum, and the increase in product weight can also be kept to a minimum.

[0039] (Other variations) In the above embodiments and modifications, a lead-acid battery 1 with a rated capacity of 1500Ah was used as an example, but a lead-acid battery 1 with a rated capacity of 1000Ah may also be used. [Explanation of symbols]

[0040] 1...Lead-acid battery, 3...Electrode group, 5A...Positive terminal, 5B...Negative terminal, 7...Case, 8...Main body, 9...Lid, 10...Positive electrode, 12...Negative electrode, 13...Separator, 31...Outer surface, 32...Inner surface, 38...First cylindrical part, 38a...Inner circumferential surface, 51...First rib (rib), 52...Second rib (rib), 91...First side (short side), 92...Second side (long side), A1...First region, A2...Second region, P...Inner circumferential surface portion, S...Housing space, VL1...First virtual straight line.

Claims

1. A lead-acid battery comprising a case having a main body that forms a single housing space for housing an electrode group to which positive and negative terminals are connected, and a rectangular lid that covers the single housing space and through which the positive and negative terminals are inserted, The main body is formed in a bottomed cylindrical shape by four side sections and a bottom section that separate the single storage space from the external space of the case. The lid is attached to the four side surfaces so as to face the bottom surface. A lead-acid battery wherein ribs are formed on the inner surface of the lid, and when a pair of straight lines passing through the positive terminal and the negative terminal, respectively, and parallel to the short side of the lid, are defined as first virtual straight lines, the density of the ribs in the first region, which is the inner surface area sandwiched between the pair of first virtual straight lines, in the direction in which the long side of the lid extends, is higher than the density of the ribs in the pair of second regions, which are the inner surface areas sandwiching the first region in the direction of the long side of the lid.

2. A lead-acid battery comprising a case having a rectangular lid portion through which positive terminals and negative terminals are inserted, A lead-acid battery wherein ribs are formed on the inner surface of the lid, and when a pair of straight lines passing through the positive terminal and the negative terminal and parallel to the short side of the lid are defined as the first virtual straight lines, and a pair of straight lines passing through the positive terminal and the negative terminal and parallel to the long side of the lid are defined as the second virtual straight lines, the density of the ribs in the first region, which is the inner surface area sandwiched between the pair of first virtual straight lines and the pair of second virtual straight lines, is higher than the density of the ribs in the second region, which is the inner surface area surrounding the first region.

3. The lead-acid battery according to claim 1 or 2, wherein the ribs are formed in both the first region and the second region.

4. The lead-acid battery according to claim 1 or 2, wherein the ratio of the area of ​​the ribs per unit area in the first region is 5% or more.

5. A lead-acid battery according to claim 1 or 2, having a rated capacity of 1000 Ah or more.

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