Lead-acid battery and method for manufacturing the same

Abstract

A lead storage battery comprising: an electrode plate group that has a positive electrode, a negative electrode, and a separator; and a case that has a body, which houses the electrode plate group and an electrolyte, and a lid that overlaps the body. The lid comprises: a plate section that has a through-hole and a recessed section that surrounds the through-hole and is disposed on the surface of the case; a bushing provided on the inner circumferential surface of the through-hole; and a filling material that fills the recessed section. The bushing has a flange that has a ring shape and is accommodated inside the recessed section. The flange has an outer circumferential surface that has a curved surface.

Description

Technical Field

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[0001] The present disclosure relates to a lead-acid battery and a method for manufacturing the same.

Background Art

[0002] As one aspect of a storage battery, a lead-acid battery is exemplified. Patent Document 1 below discloses a lead-acid battery in which the space between a terminal portion provided on a lid body and a rib is filled and cured with an adhesive. In this lead-acid battery, a protruding portion protruding toward the rib is provided at a welded portion of a lead bushing included in the terminal portion.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the configuration of the terminal portion and the rib as shown in Patent Document 1 above is adopted, for example, the adhesive may not be sufficiently filled below the protruding portion. In this case, for example, a gap may occur between the bushing and the cured adhesive. When such a gap occurs, the adhesive is likely to peel off from the bushing. As a result, there is a risk that the electrolyte leaks from the inside of the lead-acid battery through a through-hole provided in the lid and accommodating the terminal portion.

[0005] An object of one aspect of the present disclosure is to provide a lead-acid battery and a method for manufacturing the same that can suppress the outflow of the electrolyte through a through-hole provided in the lid.

Means for Solving the Problems

[0006] A lead-acid battery according to one aspect of the present disclosure comprises a group of electrode plates having a positive electrode, a negative electrode, and a separator; a case having a main body housing the group of electrode plates and an electrolyte, and a lid that overlaps the main body. The lid comprises a plate portion having a through hole and a recess surrounding the through hole and provided on the surface of the case; a bushing provided on the inner circumferential surface of the through hole; and a filler material that fills the recess. The bushing has an annular shape and a flange portion housed within the recess, and the flange portion has an outer circumferential surface that exhibits a curved surface.

[0007] In this lead-acid battery, the outer surface of the flange portion provided on the bushing is curved. In this case, when a filler material is filled into the recess, the filler material is less likely to get caught on the outer surface of the flange portion and is more likely to flow smoothly into the recess along the surface of the flange portion. As a result, gaps are less likely to form between the bushing and the filler material in the recess, and the filler material is less likely to peel off the bushing. Therefore, according to one aspect of this disclosure, it is possible to provide a lead-acid battery that can suppress the outflow of electrolyte through the through hole provided in the lid.

[0008] The flange portion may be embedded in the filler material. In this case, the flange portion functions as a retaining part for the filler material, making it difficult for the filler material to come out of the recess.

[0009] The plate portion is provided within the recess and further has a first rib surrounding the bushing, and the inner circumferential surface of the first rib may be an inclined surface that slopes away from the bushing as it approaches the tip of the first rib. In this case, when the filler is filled into the recess, the filler flows well into the recess not only through the flange portion but also along the inner circumferential surface of the first rib. This makes it less likely for a gap to form between the bushing and the filler within the recess.

[0010] In the stacking direction of the main body and the lid, the tip of the first rib may be closer to the through hole than to the flange portion. In this case, the filler material can flow more easily towards the first rib.

[0011] The bushing further has an annular portion spaced apart from the flange portion, the annular portion being exposed from the plate portion and having an exposed bottom surface corresponding to a part of the bottom surface of the recess, and the gap between the exposed bottom surface of the annular portion and the flange portion may be filled with a filler material. In this case, the portion of the filler material that fills the gap is fitted with the bushing, so the filler material is less likely to come out of the recess.

[0012] A lead-acid battery relating to another aspect of the present disclosure comprises a group of electrode plates having a positive electrode, a negative electrode, and a separator; a case having a main body housing the group of electrode plates and an electrolyte, and a lid that overlaps the main body. The lid comprises a plate portion having a through hole, a recess provided on the surface of the case and surrounding the through hole, and a first rib provided within the recess and surrounding the through hole; a bushing that is in close contact with the inner circumferential surface of the through hole; and a filler material that fills the recess. The inner circumferential surface of the first rib is an inclined surface that slopes away from the bushing as it approaches the tip of the first rib.

[0013] In this lead-acid battery, the inner circumferential surface of the first rib surrounding the bushing is an inclined surface that slopes away from the bushing as it approaches the tip of the first rib. Therefore, when a filler material is filled into the recess, the filler material flows well into the recess along the inner circumferential surface of the first rib. As a result, gaps are less likely to form between the bushing and the filler material in the recess, and the filler material is less likely to peel off the bushing. Thus, according to another aspect of this disclosure, it is possible to provide a lead-acid battery that can suppress the outflow of electrolyte through through holes provided in the lid.

[0014] The inner surface of the first rib may be more inclined than the outer surface of the first rib. In this case, the filler flows more smoothly into the recess along the inner surface. This makes it less likely for gaps to form between the bushing and the filler within the recess.

[0015] The bushing is exposed from the plate portion and has an exposed bottom surface that is ring-shaped when viewed from the stacking direction of the main body and the lid, and the width of the exposed bottom surface when viewed from the stacking direction may be 5 mm or more. In this case, sufficient bonding strength can be ensured between the exposed bottom surface and the filler material.

[0016] The bushing contains lead, and the filler contains epoxy resin. The stress generated on the exposed bottom surface when the lid deforms may be lower than the shear stress of the lead and epoxy resin. In this case, even if the lid deforms, the bond between the bushing and the filler is maintained well.

[0017] The plate portion further has a second rib provided along the outer edge of the recess, and a step may be provided at the tip of the second rib. In this case, the filler material will catch at the tip of the second rib, making it less likely for the filler material to leak out of the recess.

[0018] A method for manufacturing a lead-acid battery according to yet another aspect of the present disclosure comprises: a fixing step of fixing a lid to the body of a case that houses a group of electrode plates and an electrolyte; a welding step of welding the terminals of the group of electrode plates to a bushing provided on the lid and containing lead; a roughening step of roughening the surface of a recess provided on the surface of the lid and surrounding the bushing; a filling step of filling the recess with a liquid filler; and a hardening step of hardening the filler in the recess. The lid has ribs provided in the recess and surrounding the bushing, and the inner circumferential surface of the rib is an inclined surface that slopes away from the bushing as it approaches the tip of the rib.

[0019] In this method for manufacturing a lead-acid battery, the inner circumferential surface of the rib surrounding the bushing is an inclined surface that slopes away from the bushing as it approaches the tip of the rib. Therefore, when the filler material is filled into the recess, the filler material flows well into the recess along the inner circumferential surface of the rib. As a result, gaps are less likely to form between the bushing and the filler material in the recess, making it less likely for the filler material to peel off the bushing. In addition, since the surface of the recess is roughened, the bonding force between the surface and the filler material can be strengthened. Therefore, the filler material is less likely to peel off the surface of the recess. Accordingly, according to yet another aspect of this disclosure, it is possible to provide a method for manufacturing a lead-acid battery that can suppress the outflow of electrolyte through the through-hole provided in the lid.

[0020] In the surface roughening process, plasma may be irradiated into the recesses. In this case, even if ribs or the like are provided in the recesses, the surface of the recesses can be easily roughened.

[0021] The bushing has an annular shape when viewed from the stacking direction and has a flange portion accommodated in the recess. The flange portion has a first side surface and a second side surface that intersect the stacking direction, and an outer peripheral surface that connects the first side surface and the second side surface and exhibits a curved surface. After the welding process, at least one of the first side surface and the outer peripheral surface, and the second side surface and the outer peripheral surface may be smoothly connected. In the flange portion, at least one of the first side surface and the outer peripheral surface, and the second side surface and the outer peripheral surface is smoothly connected. In this case, when the recess is filled with a filler, the filler is unlikely to catch on the boundary between the first side surface and the outer peripheral surface and / or the boundary between the second side surface and the outer peripheral surface. Therefore, the filler can easily flow well into the recess along the surface of the flange portion.

[0022] The inner peripheral surface of the rib may be inclined more than the outer peripheral surface of the rib. In this case, the filler flows better into the recess along the inner peripheral surface of the rib. As a result, it becomes difficult to form a gap well between the bushing and the filler in the recess.

Advantages of the Invention

[0023] According to one aspect of the present disclosure, it is possible to provide a lead storage battery capable of suppressing the outflow of electrolyte through a through-hole provided in a lid and a method for manufacturing the same.

Brief Description of the Drawings

[0024] [Figure 1] FIG. 1 is a schematic exploded perspective view showing a lead storage battery according to an embodiment. [Figure 2] FIG. 2 is a schematic perspective view showing a part of the lead storage battery shown in FIG. 1. [Figure 3] FIG. 3 is a schematic perspective cross-sectional view taken along line III-III of FIG. 2. [Figure 4] FIG. 4 is a schematic cross-sectional view taken along line IV-IV of FIG. 2. [Figure 5] FIG. 5 is a flowchart for explaining a method for manufacturing a lead storage battery. [Figure 6]Figure 6(a) is a schematic perspective view showing the lid, and Figure 6(b) is a magnified view of the main part of the lid. [Figure 7] Figure 7(a) is a schematic cross-sectional view showing the bushing and terminal before welding, and Figure 7(b) is a schematic cross-sectional view showing the bushing and terminal after welding. [Modes for carrying out the invention]

[0025] Hereinafter, preferred embodiments of one aspect of this disclosure will be described in detail with reference to the attached drawings. In the following description, the same reference numerals will be used for the same elements or elements having the same function, and redundant descriptions will be omitted.

[0026] First, the configuration of the lead-acid battery 1 will be described with reference to Figure 1. Figure 1 is a schematic exploded perspective view showing the lead-acid battery according to this embodiment. As shown in Figure 1, the lead-acid battery 1 is, for example, a valve-regulated lead-acid battery. The lead-acid battery 1 comprises an electrode plate group 3, a positive electrode terminal 5A, a negative electrode terminal 5B, a control valve 6, and a case 7.

[0027] The electrode plate group 3 is an assembly of multiple electrode plates, comprising multiple positive electrodes 10, multiple negative electrodes 12, and multiple separators 13. In the electrode plate group 3, the positive electrodes 10 and negative electrodes 12 are arranged alternately. Separators 13 are located 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 the electrode plate group 3, negative electrodes 12 are located at the ends in the arrangement direction of the positive electrodes 10, negative electrodes 12, and separators 13 (hereinafter sometimes simply referred to as the "arrangement direction"). In addition, the assembly of the positive electrodes 10, negative electrodes 12, and separators 13 is also called a battery electrode group. When the electrode plate group 3 and the electrolyte are housed in the case 7, the electrolyte is present in the gaps between the positive electrodes 10 and the separators 13, inside the separators 13, etc. The above arrangement direction corresponds to the first direction X. In the following, the directions orthogonal to the first direction X will be referred to as the second direction Y and the third direction Z.

[0028] 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.

[0029] The current collector can be made of any conductive material, such as lead alloys like lead-calcium-tin alloys or 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. The material of the separator 13 can be, for example, glass fiber, resin, or inorganic material.

[0030] The positive terminal 5A and the negative terminal 5B are terminals for electrically connecting the electrode plate group 3 to an external device. Each of the positive terminal 5A and the negative terminal 5B has, for example, a first part 5a fixed to the lid 9 and a second part 5b fixed to the first part 5a (see Figures 3 and 4 described later). The first part 5a is a conductive part containing lead. The first part 5a may be formed with lead as the main component, or it may be formed from lead alone. The second part 5b is a core part formed from a metal or alloy. The second part 5b is formed from, for example, an alloy of copper and zinc (brass).

[0031] Case 7 has a main body 8 and a lid 9 that overlaps the main body 8 in the third direction Z (stacking direction). The main body 8 is a box-shaped battery case. The main body 8 is made of a material such as polypropylene. The main body 8 houses the electrode plate group 3 and the electrolyte. The main body 8 is composed of four side parts and a bottom part. The corners formed by the bottom part and the side parts are rounded.

[0032] Figure 2 is a perspective view showing a part of the lead-acid battery shown in Figure 1. Figure 3 is a perspective cross-sectional view along line III-III in Figure 2. Figure 4 is a schematic cross-sectional view along line IV-IV in Figure 2. Figure 2 mainly shows the lid 9 with the control valve 6 removed. As shown in Figures 2 to 4, the lid 9 is a member that covers the opening of the main body 8 and is made of a material such as polypropylene, similar to the main body 8. The lid 9 has a plate portion 21, bushings 22 and 23, and fillers 24 and 25. The bushings 22 and 23 are identical in shape, and the fillers 24 and 25 are made of the same material and are identical in shape. For this reason, a detailed explanation of the bushings 23 and fillers 25 will be omitted below.

[0033] (Itabe) The plate portion 21 is the main part of the lid 9 and, like the main body 8, is made of a material such as polypropylene. The plate portion 21 has a roughly hat shape when viewed from the first direction X and the second direction Y. The plate portion 21 has a main portion 21a that covers the opening of the main body 8, and an edge portion 21b that surrounds the main portion 21a and is located one level below the main portion 21a. The main portion 21a has a surface 31 and a back surface 32 that intersect in the third direction Z, through holes 33 to 35, recesses 36 and 37, and cylindrical portions 38 to 40. The through holes 33 and 34 are identical in shape, the recesses 36 and 37 are identical in shape, and the cylindrical portions 38 and 39 are identical in shape. For this reason, a detailed explanation of the through holes 34, recesses 37, and cylindrical portions 39 will be omitted below.

[0034] Surface 31 corresponds to the surface that is exposed when the lid 9 is attached to the main body 8, and has a substantially rectangular shape when viewed from the third direction Z. Surface 31 constitutes a part of the surface of the case 7. Surface 31 is provided with spaced-apart recesses 36, 37 and a cylindrical portion 40. Back surface 32 is the surface located on the opposite side of 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. Back surface 32 is provided with cylindrical portions 38, 39 and a reinforcing portion RF. The reinforcing portion RF is provided to improve the rigidity of the lid 9. The shape of the reinforcing portion RF is not particularly limited.

[0035] Each of the through holes 33 to 35 is circular in shape when viewed from the third direction Z and is an opening that extends in the third direction Z. Through hole 35 is located between through holes 33 and 34 in the second direction Y. A positive terminal 5A is provided in through hole 33, a negative terminal 5B is provided in through hole 34, and a control valve 6 is provided in through hole 35. Through hole 33 communicates with cylindrical portion 38, through hole 34 communicates with cylindrical portion 39, and through hole 35 communicates with cylindrical portion 40. For this reason, in the following, the cavity of cylindrical portion 38 is considered to be part of through hole 33, the cavity of cylindrical portion 39 is considered to be part of through hole 34, and the cavity of cylindrical portion 40 is considered to be part of through hole 35. Similarly, the inner circumferential surface 38a of the cylindrical portion 38 is considered to be part of the inner circumferential surface 33a of the through hole 33, the inner circumferential surface 39a of the cylindrical portion 39 is considered to be part of the inner circumferential surface 34a of the through hole 34, and the inner circumferential surface 40a of the cylindrical portion 40 is considered to be part of the inner circumferential surface 35a of the through hole 35.

[0036] The recess 36 is a depression on the surface 31 that surrounds the through hole 33 when viewed from a third direction Z. In this embodiment, the surface 36a of the recess 36 has an annular shape when viewed from a third direction Z. The recess 36 is provided with a first rib 41 that surrounds the through hole 34 and the bushing 22 when viewed from a third direction Z, and a second rib 42 that surrounds the first rib 41 when viewed from a third direction Z.

[0037] The first rib 41 has an annular shape when viewed from the third direction Z and is a portion provided within the recess 36. The first rib 41 protrudes from the inner edge of the surface 36a toward the surface 31 along the third direction Z. A portion of the first rib 41 is located inside the inner edge of the surface 36a. Therefore, a space S is provided between this portion of the first rib 41 and the cylindrical portion 38. In this embodiment, the cross-sectional shape of the first rib 41 perpendicular to the circumferential direction is generally trapezoidal. The first rib 41 has a top surface 41a, an inner circumferential surface 41b, an outer circumferential surface 41c, and a bottom surface 41d. The top surface 41a is the portion corresponding to the tip of the first rib 41 and has an annular shape when viewed from the third direction Z. The top surface 41a is located, for example, between the surface 31 and the tip of the second rib 42 in the third direction Z. The inner circumferential surface 41b is the opposing surface of the first rib 41 that faces the bushing 22. The inner circumferential surface 41b is an inclined surface that slopes away from the bushing 22 as it approaches the top surface 41a (tip) of the first rib 41. The angle between the top surface 41a and the inner circumferential surface 41b is greater than 90°, for example, 100° or more and 150° or less. The outer circumferential surface 41c is the opposing surface of the first rib 41 that faces the second rib 42. In this embodiment, the angle between the top surface 41a and the inner circumferential surface 41b is greater than the angle between the top surface 41a and the outer circumferential surface 41c. In other words, the inner circumferential surface 41b is more inclined than the outer circumferential surface 41c. This allows the filler material 24 to be filled well into the recess 36. The angle between the top surface 41a and the outer circumferential surface 41c is, for example, about 90°, but is not limited to this. The bottom surface 41d is a surface that extends from the surface 36a of the recess 36 toward the center of the through hole 33.

[0038] The second rib 42 has an annular shape when viewed from the third direction Z and is provided along the outer edge of the recess 36. A part of the second rib 42 is further from the back surface 32 than the front surface 31 in the third direction Z. The second rib 42 has a top surface 42a, an inner circumferential surface 42b, and an outer circumferential surface 42c. The top surface 42a is provided with a step SE consisting of a first stage 42d and a second stage 42e surrounding the first stage 42d. From the viewpoint of suppressing leakage of the filler material 24, the second stage 42e is higher than the first stage 42d. The inner circumferential surface 42b is the opposing surface of the second rib 42 that faces the first rib 41. The outer circumferential surface 42c is the surface connecting the top surface 42a and the front surface 31.

[0039] The second rib 42 is spaced apart from the first rib 41. Therefore, a groove G is provided in the recess 36 between the outer circumferential surface 41c of the first rib 41 and the inner circumferential surface 42b of the second rib 42. A filler 24 is filled into the groove G. From the viewpoint of properly filling the groove G with the filler 24, the outer circumferential surface 41c of the first rib 41 may be an inclined surface that slopes away from the second rib 42 as it approaches the tip of the first rib 41, or the inner circumferential surface 42b of the second rib 42 may be an inclined surface that slopes away from the first rib 41 as it approaches the tip of the second rib 42. In other words, the angle between the top surface 41a and the outer circumferential surface 41c of the first rib 41 may be greater than 90°, or the angle between the top surface 42a and the inner circumferential surface 42b of the second rib 42 may be greater than 90°.

[0040] The cylindrical portion 38 has a substantially cylindrical shape when viewed from the third direction Z and extends in the third direction Z. When the lid 9 is attached to the main body 8, the cylindrical portion 38 protrudes from the back surface 32 toward the electrode plate group 3. The cylindrical portion 38 has an inner circumferential surface 38a, a first end 38b, and a second end 38c which is closer to the electrode plate group 3 than the first end 38b. The inner circumferential surface 38a of the cylindrical portion 38 is continuous with the inner circumferential surface 33a of the through hole 33 via the first end 38b. For this reason, as described above, the inner circumferential surface 38a of the cylindrical portion 38 can be considered as a part of the inner circumferential surface 33a of the through hole 33. A part of the inner circumferential surface 38a is provided with an uneven surface 38d. A hook 38e is provided on the second end 38c. The hook 38e is provided along the inner edge of the second end 38c and is a projection that protrudes toward the surface 31 in the third direction Z.

[0041] The cylindrical portion 40 is the part of the lid 9 to which the control valve 6 is mounted. The cylindrical portion 40 has a substantially cylindrical shape when viewed from the third direction Z and extends in the third direction Z.

[0042] (Bushing) The bushing 22 is part of the first portion 5a of the positive terminal 5A. The bushing 22 is a cylindrical member provided on the inner circumferential surface 33a of the through hole 33. More specifically, the bushing 22 is provided on the inner circumferential surface 33a. In this embodiment, the bushing 22 is in close contact with the inner circumferential surface 33a. The bushing 22 is a material mainly composed of lead, or a material formed from lead. In the positive terminal 5A, the bushing 22 is integrated with the other part of the first portion 5a via a connecting portion C. The connecting portion C is a welded portion formed by welding the bushing 22 to the other part. The bushing 22 has an annular portion 51, a first projection 52, a second projection 53, and a flange portion 54.

[0043] The annular portion 51 is a ring-shaped portion when viewed from the third direction Z, and is located on the cylindrical portion 38 side of the recess 36 in the third direction Z. A part of the annular portion 51 is located between the cylindrical portion 38 and the first rib 41 in the third direction Z. Furthermore, this part of the annular portion 51 extends into the space S. In addition, this part is in close contact with the inner circumferential surface 33a of the through hole 33, the first end 38b of the cylindrical portion 38, and the bottom surface 41d of the first rib 41. Therefore, the movement of the bushing 22 in the third direction Z is suppressed by the cylindrical portion 38 and the first rib 41. In addition, fluids such as electrolyte are less likely to pass between the surface of the annular portion 51 and the lid 9. When the bushing 22 is viewed from the surface 31 side of the lid 9 along the third direction Z, the surface 51a (exposed bottom surface) of the annular portion 51 exposed from the plate portion 21 has an annular shape. Surface 51a corresponds to a part of the bottom surface of the recess 36. From the viewpoint of the bonding force between the bushing 22 and the filler 24, the width W of the surface 51a viewed from the third direction Z is, for example, 5 mm or more. The width W may also be 6 mm or more, 8 mm or more, or 10 mm or more. In this case, the stress generated on the surface 51a of the annular portion 51 of the bushing 22 when the lid 9 deforms will be 10 MPa or less, which is lower than the shear stress of lead and epoxy resin.

[0044] The stress generated on the surface 51a of the annular portion 51 of the bushing 22 during deformation of the lid 9 is estimated, for example, by using the analysis software Femtet2019 (Murata Software Corporation) and the von Mises stress distribution when the control valve 6 of the lid 9 is indented by 1 cm. The shear stress of lead and epoxy resin is measured by a tensile shear test in accordance with JIS K 6850:1999 and is approximately 12 MPa. When the width W is 3 mm, the stress generated on the surface 51a of the annular portion 51 of the bushing 22 during deformation of the lid 9 is 16 MPa, which is higher than the above shear stress.

[0045] The first projection 52 is a cylindrical portion when viewed from a third direction Z, and extends from the annular portion 51 toward the second end 38c of the cylindrical portion 38 in the third direction Z. The first projection 52 has an outer circumferential surface 52a, an inner circumferential surface 52b, and a tip surface 52c. The outer circumferential surface 52a is a surface that is in close contact with the inner circumferential surface 38a of the cylindrical portion 38. For this reason, the outer circumferential surface 52a is provided with irregularities that fit into the uneven surface 38d of the cylindrical portion 38. As a result, fluids such as electrolytes are less likely to pass between the inner circumferential surface 38a of the cylindrical portion 38 and the outer circumferential surface 52a of the first projection 52. A part of the inner circumferential surface 52b may be an inclined surface that slopes closer to the cylindrical portion 38 as it approaches the tip surface 52c. In this embodiment, this part is located on the tip side of the first projection 52. A part of the tip surface 52c contacts the second end 38c of the cylindrical portion 38. A hook 38e is embedded in the tip surface 52c. This suppresses the movement of the bushing 22 in both the first direction X and the second direction Y.

[0046] The second projection 53 is a cylindrical portion when viewed from the third direction Z and is housed within the recess 36. The second projection 53 extends from the annular portion 51 toward the surface 31 in the third direction Z. A portion of the second projection 53 is welded to the other portion of the first portion 5a. The top surface 53a of the second projection 53 is smoothly connected to the surface of the other portion of the first portion 5a via the connecting portion C. In other words, the top surface 53a is continuously connected to the surface without any steps. In this case, fluid located on the surface of the other portion of the first portion 5a is more likely to flow toward the top surface 53a. The top surface 53a is an inclined surface that slopes closer to the surface 51a as it approaches the first rib 41.

[0047] The flange portion 54 is an annular shape and is housed within the recess 36. The flange portion 54 may be considered to have an annular shape if it is an annular shape when viewed from the third direction Z. The flange portion 54 is provided on the second projection 53 and is spaced apart from the surface 51a of the annular portion 51. In the third direction Z, the distance between the flange portion 54 and the surface 51a of the annular portion 51 is, for example, 3 mm or more. The gap between the flange portion 54 and the surface 51a is filled with filler material 24. In a direction perpendicular to the third direction Z, the amount of protrusion of the flange portion 54 from the second projection 53 is, for example, 3 mm or more. In this case, the flange portion 54 can function well as a latching portion for the filler material 24. Also, in a direction perpendicular to the third direction Z, the distance between the flange portion 54 and the first rib 41 is, for example, 1 mm or more. In this case, the filler material 24 can easily pass between the flange portion 54 and the first rib 41. The flange portion 54 is closer to the annular portion 51 than the top surface 41a of the first rib 41 in the third direction Z. In this embodiment, in the third direction Z, the top surface 41a of the first rib 41 is closer to the through hole 33 than the flange portion 54. The flange portion 54 has a first side surface 54a and a second side surface 54b that intersect in the third direction Z, and an outer peripheral surface 54c that connects the first side surface 54a and the second side surface 54b and exhibits a curved surface.

[0048] The first side surface 54a is the top surface of the flange portion 54 and is smoothly connected to the top surface 53a of the second projection 53. In other words, the first side surface 54a is continuously connected to the top surface 53a without any steps. The first side surface 54a is an inclined surface that slopes closer to the surface 51a as it moves away from the second projection 53. As a result, fluid (e.g., filler 24) located on the first side surface 54a can easily flow toward the annular portion 51.

[0049] The second side surface 54b is the bottom surface of the flange portion 54 and is the opposing surface facing the annular portion 51 in the third direction Z. The second side surface 54b may also be an inclined surface that slopes away from the surface 51a as it approaches the second protrusion 53. In this case, fluid in the recess 36 can easily penetrate into the gap between the flange portion 54 and the surface 51a of the annular portion 51.

[0050] The outer circumferential surface 54c is the leading edge of the flange portion 54 and is a curved surface that protrudes toward the first rib 41. The first side surface 54a and the outer circumferential surface 54c, and the second side surface 54b and the outer circumferential surface 54c are smoothly connected to each other. In other words, the outer circumferential surface 54c is continuously connected to the first side surface 54a and the second side surface 54b without any steps. Also, as shown in Figure 4, there are no sharp edges at the boundary between the first side surface 54a and the outer circumferential surface 54c, and no sharp edges at the boundary between the second side surface 54b and the outer circumferential surface 54c. In this embodiment, the first corner 54d formed by the first side surface 54a and the outer circumferential surface 54c, and the second corner 54e formed by the second side surface 54b and the outer circumferential surface 54c are rounded. The first corner 54d and the second corner 54e correspond to, for example, the position (inflection point) where the outer circumferential surface 54c changes.

[0051] (filling material) The filler material 24 is a member that protects the bushing 22, etc., and is filled into the recess 36. The filler material 24 covers at least the entire bushing 22, the first rib 41, and the first stage 42d of the second rib 42. In this embodiment, the entire bushing 22 and the entire first rib 41 are embedded by the filler material 24. For this reason, for example, the flange portion 54 provided on the bushing 22, and the gap between the flange portion 54 and the surface 51a of the annular portion 51 are also embedded by the filler material 24. The filler material 24 is, for example, a cured resin member. The resin constituting the filler material 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 material 24 may be epoxy resin. Multiple types of epoxy resins may be used. The filler material 24 may contain various additives, etc.

[0052] Next, an example of a method for manufacturing the lead-acid battery 1 according to this embodiment will be described with reference to Figures 5 to 7. Figure 5 is a flowchart illustrating the method for manufacturing the lead-acid battery. Figure 6(a) is a schematic plan perspective view showing the lid. Figure 6(b) is an enlarged view of the main part of the lid. Figure 7(a) is a schematic cross-sectional view showing the bushing and terminals before welding. Figure 7(b) is a schematic cross-sectional view showing the bushing and terminals after welding.

[0053] First, as shown in Figure 5, the lid 9 is fixed to the main body 8 of the case 7 that houses the electrode plate group 3 and the electrolyte (first step ST1, fixing step). In the first step ST1, the lid 9 shown in Figure 6(a) is heat-welded to the main body 8. As shown in Figure 6(b) and Figure 7(a), the lid 9 is provided with insert-molded bushings 22A and 23A. Therefore, the bushing 22A (especially the annular portion 51 and the first projection 52) is in close contact with the lid 9. In addition, the bushing 22A is sandwiched between the cylindrical portion 38 and the first rib 41 provided on the lid 9 in the third direction Z. On the other hand, immediately after the first step ST1, the bushing 22A is spaced apart from the terminals 5 of the electrode plate group 3. Although not shown, the bushing 23A is similarly in close contact with the lid 9 and spaced apart from another terminal of the electrode plate group 3.

[0054] As shown in Figure 7(a), immediately after the first step ST1, the corners 54f and 54g included in the flange portion 54A of the bushing 22A are not rounded. In other words, as shown in Figure 7(a), the cross-sectional shape of the corners 54f and 54g is pointed. Therefore, the flange portion 54A included in the bushing 22A immediately after the first step ST1 and the flange portion 54 of the bushing 22 included in the lead-acid battery 1 that is manufactured later have different shapes.

[0055] Next, each terminal of the electrode plate group 3 is welded to the bushings 22A and 23A (second step ST2, welding process). In the second step ST2, the terminal 5 of the electrode plate group 3 is welded to the bushing 22A. As a result, as shown in Figure 7(b), the bushing 22A is integrated with the terminal 5 via the connecting portion C, and the positive electrode terminal 5A is formed. In the second step ST2, the terminal 5 and the bushing 22A are welded for 10 seconds or more, for example by arc discharge. At this time, the flange portion 54A (especially the corners 54f and 54g) of the bushing 22A is deformed due to the heat transmitted to the flange portion 54A. Thus, after the second step ST2, a bushing 22 is formed that includes a flange portion 54 having a curved outer surface 54c and rounded first corners 54d and second corners 54e. In the second step ST2, another terminal of the electrode plate group 3 is welded to the bushing 23A. This forms the negative terminal 5B and the bushing 23.

[0056] Next, the surface 31 of the lid 9 is roughened (third step ST3, roughening step). In the third step ST3, at least the surface 36a of the recess 36 surrounding the bushing 22 and the surface 37a of the recess 37 surrounding the bushing 23 (see Figure 6(a)) are roughened. At this time, the third step ST3 is carried out so that the inner circumferential surface 41b of the first rib 41 is reliably roughened. In this embodiment, at least the surfaces 36a and 37a are irradiated with plasma. After the third step ST3, the surface roughness (e.g., arithmetic mean roughness) of the surface 31 becomes greater than, for example, the surface roughness of the back surface 32.

[0057] Next, the fillers 24 and 25 are filled into the recesses 36 and 37, respectively (fourth step ST4, filling step). In the fourth step ST4, liquid filler 24 is filled into the recess 36, and liquid filler 25 is filled into the recess 37. Subsequently, the fillers 24 and 25 in the recesses 36 and 37 are cured (fifth step ST5, curing step). In the fifth step ST5, the fillers 24 and 25 are cured, for example, by ultraviolet irradiation. This firmly seals the case 7. After the fifth step ST5, the lead-acid battery 1 is manufactured by performing chemical treatment or the like.

[0058] The effects and benefits of the lead-acid battery 1 manufactured by the manufacturing method according to the embodiment described above will now be explained. For example, when a terminal portion and rib configuration as shown in Patent Document 1 is adopted, as described above, the adhesive (filler) may not be sufficiently filled below the protruding portion. In this case, for example, a gap may be created between the bushing and the hardened adhesive. When such a gap occurs, electrolyte that has crawled up from inside the lead-acid battery along the surface of the through hole in which the bushing is housed may seep into the gap. In this case, the electrolyte remains outside the lead-acid battery. The electrolyte remaining in the gap tends to accelerate the deterioration of the bonding strength between the bushing and the adhesive. As a result, the adhesive becomes more likely to peel off the bushing, and the gap between the bushing and the adhesive widens. Ultimately, this gap becomes connected to the outside, and electrolyte leaks from inside the lead-acid battery through the through hole provided in the lid.

[0059] In contrast, in this embodiment, the outer circumferential surface 54c of the flange portion 54 provided on the bushing 22 is curved. In this case, when the filler material 24 is filled into the recess 36, the filler material 24 is less likely to get caught on the outer circumferential surface 54c of the flange portion 54 and is more likely to flow smoothly into the recess 36 along the surface of the flange portion 54. As a result, a gap is less likely to form between the bushing 22 and the filler material 24 in the recess 36, and the filler material 24 is less likely to peel off from the bushing 22. Therefore, according to this embodiment, it is possible to provide a lead-acid battery 1 that can suppress the outflow of electrolyte through the through holes 33 and 34 provided in the lid 9.

[0060] In addition, in this embodiment, in the flange portion 54 provided on the bushing 22, both the first side surface 54a and the outer peripheral surface 54c, and the second side surface 54b and the outer peripheral surface 54c are smoothly connected. Therefore, when the filler material 24 is filled into the recess 36, the filler material 24 is less likely to get caught on the first corner portion 54d, which is the boundary between the first side surface 54a and the outer peripheral surface 54c, and the second corner portion 54e, which is the boundary between the second side surface 54b and the outer peripheral surface 54c. As a result, the filler material 24 can flow more smoothly within the recess 36 along the surfaces of the flange portion 54, namely the first side surface 54a, the outer peripheral surface 54c, and the second side surface 54b. This makes it easier for the filler material 24 to fill gaps that are created due to the presence of the flange portion 54 (i.e., the gap between the flange portion 54 and the surface 51a of the annular portion 51), for example. Furthermore, the inner circumferential surface 41b of the first rib 41, which is provided in the recess 36 and surrounds the bushing 22, is an inclined surface that slopes away from the bushing 22 as it approaches the tip of the first rib 41. As a result, the liquid filler 24 flows well into the recess 36 even along the inner circumferential surface 41b of the first rib 41. This makes it less likely for a gap to form between the bushing 22 and the filler 24 within the recess 36, and thus the filler 24 is less likely to peel off from the bushing 22. Here, in the first rib 41, the inner circumferential surface 41b may be more inclined than the outer circumferential surface 41c (i.e., the angle between the top surface 41a and the inner circumferential surface 41b may be greater than the angle between the top surface 41a and the outer circumferential surface 41c). This allows the filler material 24 to be effectively guided into a narrow area within the recess 36 (for example, the gap between the flange portion 54 and the surface 51a of the annular portion 51), further reducing the likelihood of gaps forming between the bushing 22 and the filler material 24 within the recess 36.

[0061] In this embodiment, the flange portion 54 is embedded in the filler material 24. Therefore, the flange portion 54 functions as a retaining part for the filler material 24, making it difficult for the filler material 24 to come out of the recess 36.

[0062] In this embodiment, in the third direction Z, the top surface 41a, which is the tip of the first rib 41, is closer to the through hole 33 than the flange portion 54. Therefore, the filler material 24 is more likely to flow towards the first rib 41.

[0063] In this embodiment, the bushing 22 has a surface 51a that is exposed from the plate portion 21 and has an annular shape when viewed from the third direction Z, and the width of the surface 51a when viewed from the third direction Z is 5 mm or more. Therefore, sufficient bonding strength can be ensured between the surface 51a and the filler 24. In addition, in this embodiment, the gap between the surface 51a, which corresponds to a part of the bottom surface of the recess 36, and the flange portion 54 is filled with filler 24. In this case, the portion of the filler 24 that is filled in the gap is fitted with the bushing 22 (especially the surface 51a and the flange portion 54), so the filler 24 is less likely to come out of the recess 36. Furthermore, the bushing 22 contains lead and the filler 24 contains epoxy resin, and the stress generated on the surface 51a when the lid 9 deforms is lower than the shear stress of the lead and epoxy resin. Therefore, even if the lid 9 deforms, the bond between the bushing 22 and the filler 24 is maintained well.

[0064] In this embodiment, the plate portion 21 is provided along the outer edge of the recess 36 and has a second rib 42 that is ring-shaped when viewed from the third direction Z, and a step SE is provided on the top surface 42a, which is the tip of the second rib 42. As a result, the filler material 24 gets caught on the top surface 42a of the second rib 42, making it difficult for the filler material 24 to leak out of the recess 36.

[0065] In this embodiment, in the third step ST3, which is a surface roughening process, plasma is irradiated onto the recess 36. In this case, the plasma can be effectively irradiated onto the inner circumferential surface 41b of the first rib 41. As a result, the surface 36a of the recess 36 can be effectively roughened.

[0066] A lead-acid battery and a method for manufacturing the same relating to one aspect of this disclosure are described, for example, in [1] to

[14] below, and these have been described in detail based on the above embodiments. [1] A group of electrode plates having a positive electrode, a negative electrode, and a separator, The system comprises a main body that houses the electrode plate group and electrolyte, and a case having a lid that overlaps the main body, The lid comprises a plate portion having a through hole and a recess surrounding the through hole and provided on the surface of the case, a bushing provided on the inner circumferential surface of the through hole, and a filler material that fills the recess. The bushing has an annular shape and a flange portion that is housed within the recess. The flange portion has a curved outer surface, and the lead-acid battery is otherwise. [2] The lead-acid battery according to [1], wherein the flange portion is embedded in the filler material. [3] The plate portion further has a first rib provided in the recess and surrounding the bushing, The lead-acid battery according to [1] or [2], wherein the inner circumferential surface of the first rib is an inclined surface that slopes away from the bushing as it approaches the tip of the first rib. [4] In the stacking direction of the main body and the lid, the tip of the first rib is closer to the through hole than the flange portion, as described in [3]. [5] The bushing further has an annular portion spaced apart from the flange portion, The annular portion is exposed from the plate portion and has an exposed bottom surface that corresponds to a part of the bottom surface of the recess, The lead-acid battery according to [1] or [2], wherein the gap between the exposed bottom surface of the annular portion and the flange portion is filled with the filler material. [6] A group of electrode plates having a positive electrode, a negative electrode, and a separator, The system comprises a main body that houses the electrode plate group and electrolyte, and a case having a lid that overlaps the main body, The lid comprises a through hole, a recess provided on the surface of the case and surrounding the through hole, a plate portion provided within the recess and having a first rib surrounding the through hole, a bushing that is in close contact with the inner circumferential surface of the through hole, and a filler material that is filled into the recess. The inner circumferential surface of the first rib is an inclined surface that slopes away from the bushing as it approaches the tip of the first rib, in a lead-acid battery. [7] The lead-acid battery according to [6], wherein the inner surface is inclined more than the outer surface of the first rib. [8] The bushing is exposed from the plate portion and has an exposed bottom surface that is ring-shaped when viewed from the stacking direction of the main body and the lid, The width of the exposed bottom surface as viewed from the stacking direction is 5 mm or more, as described in any of [1] to [7]. [9] The bushing contains lead, The aforementioned filler includes epoxy resin, The lead-acid battery described in [8], wherein the stress generated on the exposed bottom surface when the lid deforms is lower than the shear stress of the lead and epoxy resin.

[10] The plate portion further has a second rib provided along the edge of the recess, A step is provided at the tip of the second rib, according to any one of claims [1] to [8].

[11] A fixing step of fixing the lid to the main body of the case that houses the electrode plate group and the electrolyte, A welding step of welding the terminals of the electrode plate group to a bushing provided on the cover and containing lead, A roughening step is performed to roughen the surface of the recess provided on the surface of the lid and surrounding the bushing, A filling step of filling the recess with a liquid filler, The process includes a curing step for curing the filler material in the recess, The lid is provided in the recess and has ribs surrounding the bushing, A method for manufacturing a lead-acid battery, wherein the inner circumferential surface of the rib is an inclined surface that slopes away from the bushing as it approaches the tip of the rib.

[12] The method for manufacturing a lead-acid battery according to

[11] , wherein the roughening step involves irradiating the surface of the recess with plasma.

[13] The bushing has an annular shape when viewed from the stacking direction of the body and the lid and has a flange portion that is housed in the recess, The flange portion has a first side surface and a second side surface that intersect the stacking direction, and an outer peripheral surface that connects the first side surface and the second side surface and exhibits a curved surface. A method for manufacturing a lead-acid battery according to

[11] or

[12] , wherein, after the welding process, at least one of the first side surface and the outer peripheral surface, and the second side surface and the outer peripheral surface are smoothly connected.

[14] The method for manufacturing a lead-acid battery according to any one of

[11] to

[13] , wherein the inner circumferential surface of the rib is inclined more than the outer circumferential surface of the rib.

[0067] However, one aspect of the present disclosure is not limited to the above embodiments and [1] to

[14] . One aspect of the present disclosure can be further modified without departing from its essence. For example, in the above embodiments, the first side surface and the outer surface, and the second side surface and the outer surface are smoothly connected to each other, but are not limited thereto. For example, the first side surface and the outer surface, or the second side surface and the outer surface, may be smoothly connected. In addition, in the above embodiments, the inner surface of the first rib is inclined, but is not limited thereto. For example, if the first side surface and the outer surface, and / or the second side surface and the outer surface are smoothly connected, the inner surface of the first rib does not have to be inclined. Or, if the inner surface of the first rib is inclined, for example, at least one of the first side surface and the outer surface, and the second side surface and the outer surface, does not have to be smoothly connected.

[0068] In the above embodiment, the flange portion is provided with a first corner and a second corner, but is not limited to this. In other words, in the flange portion, the boundary between the first side surface and the outer circumferential surface does not need to be distinguishable, nor does the boundary between the second side surface and the outer circumferential surface.

[0069] In the above embodiment, the first rib has a top surface, but is not limited to this. When viewed from the stacking direction, the tip of the first rib may be linear. [Explanation of Symbols]

[0070] 1...Lead-acid battery, 3...Electrode plate group, 5...Terminal, 5A...Positive terminal, 5B...Negative terminal, 6...Control valve, 7...Case, 8...Main body, 9...Lid, 10...Positive electrode, 12...Negative electrode, 13...Separator, 21...Plate part, 21a...Main part, 21b...Edge part, 22, 22A, 23, 23A...Bushing, 24, 25...Filler material, 31...Surface, 32...Back surface, 33~35...Through hole, 33a, 34a, 35a...Inner circumferential surface, 36, 37...Recess, 36a, 37a...Surface, 38~40...Cylinder part, 38a, 39a, 40a...Inner circumferential surface, 38b...First end, 38c...Second end, 38d...Uneven surface, 38e...Hook, 4 1...First rib, 41a, 42a...Top surface, 41b, 42b...Inner peripheral surface, 41c, 42c...Outer peripheral surface, 41d...Bottom surface, 42...Second rib, 42d ...First stage, 42e...Second stage, 51...Annular part, 51a...Face (exposed bottom surface), 52...First protrusion, 52a...Outer peripheral surface, 52b...Inner peripheral surface, 52c... Tip surface, 53...second protrusion, 53a...top surface, 54,54A...flange section, 54a...first side surface, 54b...second side surface, 54c...outer surface, 54d...first corner section, 54e...second corner section, 54f, 54g...corner section, C...connection section, G...groove, RF...reinforcement section, S...space, SE...step, W...width.

Claims

1. A group of electrode plates having a positive electrode, a negative electrode, and a separator, The system comprises a main body that houses the electrode plate group and electrolyte, and a case having a lid that overlaps the main body, The aforementioned lid is A plate portion having a through hole and a recess that surrounds the through hole and is provided on the surface of the case, A bushing provided on the inner circumferential surface of the through hole, The system comprises a filler material that fills the recess, The bushing has an annular shape and a flange portion that is housed within the recess. The flange portion has an outer surface whose cross-sectional shape perpendicular to the circumferential direction of the flange portion exhibits a curved surface. Lead acid battery.

2. The flange portion is embedded in the filler material, as described in claim 1.

3. The plate portion further has a first rib that is provided in the recess and surrounds the bushing, The lead-acid battery according to claim 1 or 2, wherein the inner circumferential surface of the first rib is an inclined surface that slopes away from the bushing as it approaches the tip of the first rib.

4. The lead-acid battery according to claim 3, wherein in the stacking direction of the main body and the lid, the tip of the first rib is closer to the through hole than the flange portion.

5. The bushing further has an annular portion spaced apart from the flange portion, The annular portion is exposed from the plate portion and has an exposed bottom surface that corresponds to a part of the bottom surface of the recess, The lead-acid battery according to claim 1 or 2, wherein the gap between the exposed bottom surface of the annular portion and the flange portion is filled with the filler material.

6. A group of electrode plates having a positive electrode, a negative electrode, and a separator, The system comprises a main body that houses the electrode plate group and electrolyte, and a case having a lid that overlaps the main body, The aforementioned lid is A through hole, a recess provided on the surface of the case and surrounding the through hole, and a plate portion provided within the recess and having a first rib surrounding the through hole, A bushing that is in close contact with the inner circumferential surface of the through hole, The system comprises a filler material that fills the recess, The inner circumferential surface of the first rib is an inclined surface that slopes away from the bushing as it approaches the tip of the first rib. The bushing has an annular shape and a flange portion that is housed within the recess. The flange portion has an outer surface whose cross-sectional shape perpendicular to the circumferential direction of the flange portion exhibits a curved surface. Lead acid battery.

7. The lead-acid battery according to claim 6, wherein the inner circumferential surface is inclined more than the outer circumferential surface of the first rib.

8. The bushing is exposed from the plate portion and has an exposed bottom surface that is ring-shaped when viewed from the stacking direction of the main body and the lid. The lead-acid battery according to any one of claims 1, 2, 6, or 7, wherein the width of the exposed bottom surface as viewed from the stacking direction is 5 mm or more.

9. The aforementioned bushing contains lead, The aforementioned filler includes epoxy resin, The lead-acid battery according to claim 8, wherein the stress generated on the exposed bottom surface when the lid deforms is lower than the shear stress of the lead and epoxy resin.

10. The plate portion further has a second rib provided along the edge of the recess, A step is provided at the tip of the second rib, according to any one of claims 1, 2, 6, or 7.

11. A fixing step involves fixing the lid to the main body of the case that houses the electrode plate group and the electrolyte, A welding step of welding the terminals of the electrode plate group to a bushing provided on the cover and containing lead, A roughening step is performed to roughen the surface of the recess provided on the surface of the lid and surrounding the bushing, A filling step of filling the recess with a liquid filler, A curing step for curing the filler material in the recess, Equipped with, The lid is provided in the recess and has ribs surrounding the bushing, The inner circumferential surface of the rib is an inclined surface that slopes away from the bushing as it approaches the tip of the rib. The bushing has an annular shape when viewed from the stacking direction of the main body and the lid, and has a flange portion that is housed in the recess. The flange portion has a first side surface and a second side surface that intersect the stacking direction, and an outer circumferential surface that connects the first side surface and the second side surface and has a curved cross-sectional shape perpendicular to the circumferential direction of the flange portion. A method for manufacturing lead-acid batteries.

12. The method for manufacturing a lead-acid battery according to claim 11, wherein the surface roughening step involves irradiating the surface of the recess with plasma.

13. The method for manufacturing a lead-acid battery according to claim 11 or 12, wherein, after the welding process, at least one of the first side surface and the outer peripheral surface, and the second side surface and the outer peripheral surface are smoothly connected.

14. The method for manufacturing a lead-acid battery according to claim 11 or 12, wherein the inner circumferential surface of the rib is inclined more than the outer circumferential surface of the rib.

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