Lead-acid battery and battery case

Abstract

To effectively suppress the bending of an electrode plate group in a lead acid battery that has a locally narrow portion such as an EN standard.SOLUTION: A battery case 2 includes a partition wall 11, which is a facing surface having ribs abutting on an electrode plates 5X positioned at both ends of an electrode plate group 5, and a narrow portion 31 in which the inner space is locally narrowed toward the inner side in the width direction of the electrode plate group 5, and the ribs are in contact with both ends of the electrode plate 5X in the width direction in the vertical range of the narrow portion 31, the contact surface 25T includes third ribs 25, which are contact ribs on both ends of the electrode plate, extending outward in the width direction from both ends in the width direction along the surface of the electrode plate 5X.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a lead storage battery and a battery case.

Background Art

[0002] A lead storage battery mounted on a vehicle or the like includes a battery case that houses a plate group and an electrolyte. The plate group has a structure in which separators are laminated between a plurality of plates. Some batteries of this type are provided with a partition wall that divides the inside of the battery case into a plurality of cell chambers, and a vertical rib that applies a uniform pressing force to each plate group on the inner surface of the end of the battery case (for example, Patent Document 1). In recent years, due to efforts to address environmental issues, the number of idling stop vehicles, electric vehicles, etc. has been increasing, and the adoption of lead storage batteries with a design standard called the EN standard (European Norm) has been increasing for these environmentally friendly vehicles.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a lead storage battery, with the use of the battery, deformation due to corrosion of the plates occurs. This deformation includes deformation due to elongation called growth (also referred to as low-speed creep deformation), which causes the plates to bend. In a lead storage battery complying with the EN standard, the lower part of the battery case is locally narrowed toward the inner side in the width direction of the plate group. Not limited to the EN standard battery case, in the case of a battery case having a locally narrow portion, the space for growth to escape changes from the width direction to the thickness (lamination) direction of the plate group, resulting in a decrease in the escape space. Then, the plate group may bend in the thickness direction, leading to a decrease in battery performance due to an increase in internal resistance or the like.

[0005] Therefore, an object of the present invention is to effectively suppress the bending of the electrode plate group even in a lead-acid battery having locally narrow portions such as EN standards.

Means for Solving the Problems

[0006] In order to solve the above-described problems, a lead-acid battery of the present invention is a lead-acid battery including an electrode plate group in which a plurality of electrode plates and separators are laminated, and a battery case that houses the electrode plate group, The electrolytic cell has a rectangular plate-shaped bottom plate, the long side of the bottom plate extends in the stacking direction of the electrode plate group, and the short side of the bottom plate extends in the width direction of the electrode plate. the battery case has a facing surface having ribs that contact the electrode plates located at both ends of the electrode plate group In the stacking direction and a narrow portion that locally narrows the internal space toward the inner side in the width direction of the electrode plate group, and the rib Vertical ribs that extend in the vertical direction with a space in the width direction of the electrode plate, in the range of the narrow portion Of height contacts both ends in the width direction of the electrode plate, and the contact surface includes electrode plate end contact ribs that extend outward in the width direction from the both ends in the width direction of the electrode plate along the surface of the electrode plate.

[0007] In the above configuration Um, the the electrode plate end contact ribs may extend from the inner surface of the side wall on the long side of the Bottom plate by at least 1 / 5 of the distance to the vertical ribs located at both ends outward in the width direction. Of the electrode plate outward in the width direction Of to the vertical ribs located at both ends.

[0008] In the above configuration Um, the the electrode plate end contact ribs may be connected to any of the vertical ribs. In the above configuration, the electrode plate end contact ribs may extend outward in the width direction from the vertical ribs located at both ends outward in the width direction by the same protruding amount as each vertical rib.

[0009] In the above configuration, the electrode plate end contact ribs may be provided at intervals in the width direction and may contact the corner portions at both ends in the width direction of the electrode plate, respectively.

[0010] In the above configuration, the electrode plate end contact ribs may be connected to both ends in the width direction of the Electrode plate and the bottom plate of the battery case.

[0011] In the above configuration, the rib that abuts against both ends of the electrode plate may not be formed above the narrow portion.

[0012] Further, the battery case of the present invention is a battery case for a lead-acid battery that houses a group of electrode plates in which a plurality of electrode plates and separators are stacked. The electrolytic cell has a rectangular plate-shaped bottom plate, the long side of the bottom plate extends in the stacking direction of the electrode plate group, and the short side of the bottom plate extends in the width direction of the electrode plate. The group of electrode plates In the stacking direction has a facing surface having ribs that abut against the electrode plates located at both ends, and a narrow portion that locally narrows the internal space toward the inner side in the width direction of the group of electrode plates. The rib Vertical ribs that extend in the vertical direction with a space in the width direction of the electrode plate, within the range of the narrow portion Of height abuts against both ends in the width direction of the electrode plate, and the abutting surface includes electrode plate both-end abutting ribs that extend outward in the width direction from both ends in the width direction along the surface of the electrode plate.

Advantages of the Invention

[0013] According to the present invention, even in a lead-acid battery having a locally narrow portion such as an EN standard, the bending of the group of electrode plates can be effectively suppressed.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Best Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described. FIG. 1 is a perspective view of a lead storage battery according to an embodiment of the present invention. The lead storage battery 1 includes a rectangular parallelepiped-shaped battery case 2, a positive electrode terminal 3A and a negative electrode terminal 3B exposed to the outside, and a lid 4 attached to the battery case 2, and conforms to the EN standard. The lead storage battery 1 of the EN standard is designed with a lower height than a lead storage battery of the JIS (Japanese Industrial Standards) standard, and there are differences such that each terminal 3A, 3B of the lid 4 is at a position lower than the upper surface of the lid 4. The lead storage battery 1 of the EN standard may also be referred to as an EN standard lead storage battery and an EN standard vehicle battery.

[0016] FIG. 2 is a view of the internal structure of the lead storage battery 1 as seen from above. The battery case 2 has its internal space partitioned into a plurality of cell chambers 12 by a plurality of partition walls 11. Each cell chamber 12 houses a plate group 5. The plate group 5 has a structure in which a plurality of plates including negative plates and positive plates and separators are laminated. The separator is a member that maintains insulation between the plates by being inserted between the plates. The separator is, for example, a sheet-like member made of polyethylene and having a porous structure. Note that a separator made of a material other than polyethylene may be applied to the separator, and known separators can be widely applied.

[0017] In FIG. 2 and each of the figures described later, the symbol X indicates the stacking direction (which also coincides with the thickness direction) of the plates in the lead storage battery 1, and the symbol Y indicates the width direction of the plates in the lead storage battery 1. As shown in FIG. 2, the battery case 2 has a rectangular shape in a top view, the X direction corresponds to the longitudinal direction of the battery case 2 and coincides with the thickness direction of each plate. The Y direction corresponds to the short side direction of the battery case 2 and coincides with the width direction of each plate. The tabs of each negative electrode plate are connected by a negative strap 6, and the tabs of each positive electrode plate are connected by a positive strap 7. The negative strap 6 and the positive strap 7 are arranged at different positions in the width direction (the direction indicated by symbol Y) of the negative electrode plate and the positive electrode plate. The electrode plate group 3 further has a negative intermediate terminal post protruding upward from one end of the negative strap 6 in the X direction and a positive intermediate terminal post protruding upward from the other end of the positive strap in the X direction.

[0018] Figure 3 is a perspective view of the battery case 2. In Figure 3, symbol Z indicates the upward direction of the lead-acid battery 1. As shown in Figures 2 and 3, the battery case 2 integrally includes a rectangular plate-shaped bottom plate 2A, a pair of first side walls 2B erected on a pair of long sides of the bottom plate 2A, a pair of second side walls 2C erected on a pair of short sides of the bottom plate 2A, and a plurality of partition walls 11 bridging between the first side walls 2B. The first side wall 2B can also be referred to as the side wall on the long side of the battery case 2. Also, the second side wall 2C can also be referred to as the side wall on the short side of the battery case 2. Note that Figure 3 shows the battery case 2 in a state of being cut near one of the second side walls 2C. The material of the battery case 2 is, for example, PE (polyethylene) or PP (polypropylene).

[0019] The first side wall 2B, the second side wall 2C, and the partition walls 11 are erected vertically, and a plurality of vertical ribs 21 (see Figure 3) extending in the vertical direction are integrally provided on both surfaces of each partition wall 11 and on the inner surface of each second side wall 2C facing the partition wall 11. Both surfaces of the partition wall 11 and the inner surface of the second side wall 2C (corresponding to the surface on the cell chamber 12 side) correspond to the opposing surfaces facing the electrode plates 2X (Figure 4) located at both ends of the electrode plate group 5. The vertical ribs 21 provided on each opposing surface are in contact with each of the electrode plates 2X facing each opposing surface. Here, the vertical ribs 21 provided on both surfaces of the partition wall 11 and the vertical ribs 21 provided on the inner surface of the second side wall 2C have the same position and shape, and duplicate descriptions will be omitted in the following explanations.

[0020] Figure 4 is a diagram showing the vertical ribs 21 provided on the partition wall 11 together with the peripheral configuration. Fig. 4 shows the outline of the electrode plates 5X located at both ends of the electrode plate group 5 with a two-dot chain line. In Fig. 4, reference symbol W1 indicates the width of the electrode plate 5X, and reference symbol H1 indicates the height of the electrode plate 5X. Note that the electrode plate 5X has a rectangular plate shape. Also, in Fig. 4, reference symbol WU indicates the upper width of the internal space of the battery case 2, and reference symbol WL indicates the lower width of the internal space of the battery case 2. As shown in Fig. 4, the upper width WU of the internal space > the lower width WL of the internal space > the width W1 of the electrode plate 5X (corresponding to the width of the electrode plate group 5).

[0021] Thus, in the lead-acid battery 1 of the EN standard, a width-reduced portion 31 that locally narrows the internal space toward the inner side in the width direction of the electrode plate group 5 is provided at the lower part of the battery case 2. This width-reduced portion 31 is in the range from the bottom surface of the internal space of the battery case 2 to a height H2. A pedestal portion 32 that projects outward is integrally provided on the outer peripheral surface of the width-reduced portion 31.

[0022] Next, the vertical ribs 21 provided on the partition wall 11 will be described. Fig. 5 is a view of the battery case 2 seen from above. As shown in Figs. 4 and 5, the vertical ribs 21 are provided integrally with the partition wall 11 at intervals in the width direction (the direction along the Y direction) of the partition wall 11. These vertical ribs 21 are formed in the regions that contact the electrode plates 5X at both ends of the electrode plate group 5. The upper ends of the respective vertical ribs 21 are located near the upper edges of the electrode plates 5X, and the lower ends of the respective vertical ribs 21 are connected to the bottom plate 2A of the battery case 2. As shown in Fig. 5, the protruding amounts of the respective vertical ribs 21 from the partition wall 11 are set to be the same.

[0023] The partition wall 11 and the vertical ribs 21 provided on each of the second side walls 2C are respectively in contact with the end plates 5X at both ends of the electrode plate group 5, whereby the end plates 5X at both ends are positioned. By these vertical ribs 21, the electrode plate group 5 is moderately compressed, and effects such as suppressing the influence of vibration and suppressing fluctuations in the separation distance between the electrode plates can be obtained. Further, a space for the electrolytic solution is formed between the partition wall 11 and the second side wall 2C and the electrode plate 5X by the amount of protrusion of the vertical rib 21. Since the electrolytic solution flows into this space, it becomes easier to secure the capacity of the electrolytic solution. Further, the vertical rib 21 also functions as a reinforcing rib for reinforcing the partition wall 11 and the second side wall 2C.

[0024] Therefore, while thinning the partition wall 11 and the second side wall 2C, the strength can be ensured, and it becomes easier to secure the capacity of the electrolytic solution. FIG. 4 illustrates a case where five ribs including a first vertical rib 21A located at the center in the width direction and four second vertical ribs 21B located on both sides of the first vertical rib 21A are provided as the vertical ribs 21, and each of the vertical ribs 21A and 21B has the same shape. However, the configuration is not limited to this. For example, although the case where the heights of all the vertical ribs 21A and 21B are made equal to the height H1 of the electrode plate 5X is illustrated, the heights of the vertical ribs 21A and 21B may be changed. Also, either of the vertical ribs 21A and 21B may be made higher than the other vertical ribs. For example, the central first rib 21A may be made higher than the second vertical rib 21B.

[0025] According to the study by the inventors, in the electrolytic cell 2, in a portion where the width is locally narrow (narrow width portion 31X), the space serving as a relief for growth changes from the width direction to the thickness (lamination) direction of the electrode plate group 5 including the electrode plate 5X, and thus the electrode plate group 5 may be curved in the thickness direction. When the electrode plate group 5 is curved, the internal resistance may increase, and mechanical stress may also act on the electrode plates and separators constituting the electrode plate group 5. When the separator is made of polyethylene, the mechanical strength of the separator is lowered due to oxidation accompanying charge and discharge. Therefore, it is also desirable to reduce the mechanical stress on the separator due to the curvature of the electrode plate group 5. Therefore, in this configuration, in order to suppress the bending of the electrode plate group 5, third ribs (electrode plate both-end contact ribs) 25 that contact both end portions in the width direction of the electrode plate 5X are provided in the upper and lower ranges of the narrow portion 31.

[0026] As shown in FIGS. 4 and 5, the third ribs 25 are provided at intervals in the width direction (Y direction) on both surfaces of the partition wall 11 and on the inner surfaces of the respective second side walls 2C facing the partition wall 13. The third ribs 25 provided on the walls 11 and 2C are provided at the same positions and in the same shapes between the opposing walls 11 and 2C and between the opposing partition walls 11. As a result, both end portions in the width direction of the electrode plates 5X located at both ends of the electrode plate group 5 are pinched between the opposing third ribs 25.

[0027] As shown in FIG. 4, the third ribs 25 are provided in the range of the height H2 of the narrow portion 31 in the height direction (Z direction), and are provided in the range extending from the positions where they contact both end portions in the width direction of the electrode plate 5X to the outside in the width direction of the electrode plate 5X in the width direction (Y direction). More specifically, the third ribs 25 are provided in a range that coincides with the height H2 of the narrow portion 31, and extend from the second vertical rib 21B located most outside in the width direction among the second vertical ribs 21B to both ends of the battery case 2 (both ends of the narrow portion 31). Also, as shown in FIG. 5, the protruding amount of the third ribs 25 from the partition wall 11 is formed to be the same as the protruding amount of each vertical rib 21 from the partition wall 11. As a result, the contact surface 25T formed by the surface of the third rib 25 is formed to have a height H2 and a width W3, and is formed in a plane parallel to the surface of the electrode plate 5X. In other words, the third rib 25 is a rib that extends along the surface of the electrode plate 5X and is formed as a rib having a height H2 and a width W3.

[0028] As shown in FIG. 4, the height of the third rib 25 (the height overlapping the electrode plate 5X) is set to be approximately one-third of the height H1 of the electrode plate 5X. Thereby, it becomes easier to secure the space for the electrolytic solution as compared with the case where the height of the third rib 25 is made to be approximately the same as or half of the height H1 of the electrode plate 5X. In addition, the height of the third rib 25 may be appropriately changed as long as the volume of the electrolytic solution and the like can be sufficiently ensured. Further, in the present embodiment, the case where the third rib 25 is formed as a rib extending outward in the width direction from the vertical ribs 21 located at both outer ends in the width direction and having the same protruding amount as each vertical rib 21B is illustrated, but the width of the third rib 25 may be appropriately changed.

[0029] By forming the third rib 25 as a rib extending along the surface of the electrode plate 5X, when deformation such as elongation of the electrode plate 5X occurs with the use of the lead storage battery 1, both end portions in the width direction of the electrode plate 5X can be guided along the contact surface 25T of the third rib 25. Further, the third rib 25 extends outward in the width direction from the electrode plate 5X. By these, while suppressing the bending of both end portions in the width direction of the electrode plate 5X, an effect of extending the electrode plate 5X outward in the width direction (an effect of deforming) can be expected. Further, since the third rib 25 is provided in the vertical range of the narrow width portion 31, it is possible to expect an effect of suppressing a situation where both end portions in the width direction of the electrode plate 5X are bent at the location of the narrow width portion 31 and effectively suppressing a situation where the separator is damaged.

[0030] Next, the above-described battery case 2 was prototyped, and a lead storage battery 1 in which the electrode plate group 5 and the electrolytic solution were housed in this battery case 2 was used as Example 1, and the following tests were conducted. Specifically, the lead storage battery 1 was subjected to a predetermined charge-discharge pattern of 4000 cycles or more in an environment (water tank or gas tank) at 75°C. The predetermined charge-discharge pattern was one in which constant current discharge (25 A × 2 min) and constant voltage charge (15.0 V (25 A) × 10 min) were taken as one cycle.

[0031] Also, a battery case 2 having a different height of the third rib 25 was prototyped, and a lead storage battery 1 in which the electrode plate group 5 and the electrolytic solution were housed in this battery case 2 was used as Example 2, and the same life test was conducted. Furthermore, a battery case 2 not provided with the third rib 25 was prototyped, and a lead storage battery 1 in which the electrode plate group 5 and the electrolytic solution were housed in this battery case 2 was used as Comparative Example 1, and the same life test was conducted.

[0032] FIG. 6 is a diagram showing the battery cases 2 of Example 1, Example 2, and Comparative Example 1, respectively. As described above, the battery cell 2 of Example 1 is configured such that the third rib 25 is provided in a range that coincides with the height H2 of the narrow portion 31. Therefore, the third rib 25 abuts against both end portions in the width direction of the electrode plate 5X only in the upper and lower ranges of the narrow portion 31. Further, the battery cell 2 of Example 2 is configured such that the upper end of the third rib 25 is aligned with the upper end of the electrode plate 2X by setting the height of the third rib 25 to be approximately the same as the height H1 of the electrode plate 2X. Therefore, in Example 2, the third rib 25 abuts against both end portions in the width direction of the electrode plate 5X over the entire upper and lower portions of the electrode plate 5X.

[0033] Further, the battery cell 2 of Comparative Example 1 is the same as the battery cells 2 of Examples 1 and 2 except that the third rib 25 does not exist. FIG. 7 is a top view schematically showing the electrode plate group 5 before and after the test of Comparative Example 1 together with the peripheral configuration. In FIG. 7, reference sign A indicates the state before the test, and reference sign B indicates the state after the test. As shown in FIG. 7, since both end portions in the width direction of the electrode plate group 5 are not pressed (since there is a gap between the electrode plate 5X and the battery cell 2), when the electrode plate group 5 including the electrode plate 5X is deformed due to growth or the like, the bending in the thickness direction of each electrode plate is not restricted. Therefore, particularly at the location of the narrow portion 31, the electrode plate group is likely to bend.

[0034] FIG. 8 is a top view schematically showing the electrode plate group 5 before and after the test of Examples 1 and 2 together with the peripheral configuration. In FIG. 8, reference sign A indicates the state before the test, and reference sign B indicates the state after the test. In both Examples 1 and 2, as shown in FIG. 8, the bending of both end portions in the width direction of the electrode plate group 5 is restricted by the third rib 25. Further, since the contact surface 25T of the third rib 25 is flat and parallel to the surface of the electrode plate 5X, the electrode plate 5X does not get caught on the contact surface 25T when it extends outward in the width direction, and it is possible to suppress bending while allowing extension. Table 1 shows the states of the electrode plate group 5 after the test of Examples 1 and 2 and Comparative Example 1.

[0035]

Table 1

[0036] As shown in Table 1, in Comparative Example 1, the electrode plate group 5 was curved in the thickness direction. That is, in Comparative Example 1, the electrode plate group 5 was curved in the thickness direction to a range exceeding a predetermined threshold value that causes an increase in internal resistance (indicated by "×" in Table 1). On the other hand, even when the charge and discharge were repeated up to the number of cycles in which the electrode plate group 5 in Comparative Example 1 was curved to the state indicated by "×", in Examples 1 and 2, the electrode plate group 5 was hardly curved or was suppressed to a slight curvature (indicated by "○" in Table 1). That is, in Examples 1 and 2, the curvature of the electrode plate group 5 could be suppressed to less than the above-mentioned threshold value. Also, between Examples 1 and 2, Example 1 was more effective in suppressing stratification (a phenomenon in which a specific gravity difference (ion concentration difference) occurs between the upper and lower parts of the electrolytic solution) because it could have a larger volume of the electrolytic solution.

[0037] As described above, in the present embodiment, the battery case 22 has ribs (21, 25) that contact the electrode plate 5X, and the ribs contact both end portions in the width direction of the electrode plate 5X in the vertical range of the narrow-width portion 31 of the battery case 2, and the contact surface 25T functions as a third rib 25 that extends outward in the width direction from both end portions in the width direction along the surface of the electrode plate 5X. Thereby, in a portion where the width of the battery case 2 is locally narrow, the situation where the electrode plate group 5 including the electrode plate 5X is curved can be effectively suppressed. Therefore, it becomes easier to suppress the situation where the battery performance deteriorates due to an increase in internal resistance or the like. Also, the ribs including the third rib 25 can secure a space for the electrolytic solution between the opposing surface of the battery case 2 and the electrode plate group 5, which is also suitable for securing a sufficient volume of the electrolytic solution and suppressing stratification.

[0038] Moreover, in the present embodiment, in the lead-acid battery 1 of the EN standard in which it is stipulated to provide the narrow-width portion 31 at the lower part of the battery case 2, since the third rib 25 is provided in the vertical range of the narrow-width portion 31, in the lead-acid battery 1 of the EN standard, the curvature of the electrode plate group 5 can be suppressed while suppressing an increase in the size of the third rib 25.

[0039] In addition, the ribs that contact the electrode plate 5X include vertical ribs 21 that extend in the vertical direction with a gap in the width direction of the electrode plate 5X, and the third rib 25 is connected to one of the vertical ribs 21. According to this configuration, the electrode plate 5X is appropriately suppressed by the vertical ribs 21 and the third rib 25, and it becomes easier to reinforce the vertical ribs 21 and the third rib 25 with each other. Note that the ribs that contact the electrode plate 5X may include ribs other than the above ribs 21 and 25 (for example, horizontal ribs that extend in the width direction).

[0040] In addition, since the third rib 25 extends outward in the width direction from the vertical ribs 21 located at both outer ends in the width direction with the same protruding amount as each vertical rib 21, the vertical rib 21 can function as a part of the electrode plate both-end contact ribs. Furthermore, since the third rib 25 is provided with a gap in the width direction of the electrode plate 5X and contacts the corner portions at both ends in the width direction of the electrode plate 5X respectively, the bending at the corner portions of the electrode plate 5X can be effectively suppressed.

[0041] In addition, since the third rib 25 is connected to both end portions in the width direction of the battery case 2 and the bottom plate 2A of the battery case 2, it is advantageous for improving the strength of the third rib 25 and the opposing surface. In addition, since the third rib 25 is not formed above the narrow width portion 31, it becomes easier to secure the space for the electrolytic solution while suppressing the bending of the electrode plate group 5 at the narrow width portion 31.

[0042] Alternatively, the third rib 25 may not be connected to the vertical rib 21. FIG. 9 is a diagram showing an example of the third rib 25 that is not connected to the vertical rib 21. In the example of FIG. 9, the difference from FIG. 4 is that the width W3 of the third rib 25 is set to a length that is not connected to the vertical ribs 21 located at both outer ends in the width direction. Here, the width W4 is the distance from the inner surface of the first side wall 2B to the closest vertical rib 21 (corresponding to the vertical ribs 21 located at both outer ends in the width direction). The third rib 25 shown in Fig. 9 extends from the inner surface of the first side wall 2B to the vertical ribs 21 located at both outer ends in the width direction. The width W3 is the length at which the contact surface 25T of the third rib 25 contacts the electrode plate 5X, and is set to be less than the width W4. The width W3 may be set to an appropriate value within a suitable length range for suppressing the bending of the electrode plate group 5. According to the study by the inventors, by making the length 1 / 5 or more (= 20% or more of the width W4) of the width W4 and making the height of the third rib 25 a predetermined length (for example, not less than the height H2 of the narrow width portion 31), it is possible to sufficiently contact both ends in the width direction of the electrode plate 5X, and it has been confirmed that it is suitable for suppressing the bending of the electrode plate group 5. Note that the width W3 and height of the third rib 25 may be appropriately changed according to the size of the electrode plate 5X and the size of the electrolytic cell 2.

[0043] Since the third rib 25 is not connected to the vertical rib 21, a space for the electrolytic solution that communicates vertically can be secured between the third rib 25 and the vertical rib 21, which is also suitable for ensuring a sufficient volume of the electrolytic solution and suppressing stratification.

[0044] The present invention is not limited to the above-described embodiments, and various modifications and changes are possible based on the technical idea of the present invention. For example, the height of the third rib 25 may be appropriately changed within a range where the volume of the electrolytic solution and the like can be sufficiently secured. Further, in the present embodiment, the case where the third rib 25 is formed as a rib that extends outward in the width direction from the vertical ribs 21 located at both outer ends in the width direction by the same protruding amount as each vertical rib 21B is illustrated, but the width of the third rib 25 may be appropriately changed. Further, the third rib 25 may be integrally formed with the partition wall 11 and the second side wall 2C, or a separate third rib 25 may be joined to the partition wall 11 and the second side wall 2C by welding or the like. As the ribs provided on the partition wall 11 and the second side wall 2C (excluding the third rib 25), ribs employed in this type of electrolytic cell may be appropriately employed. In addition, although the case where the present invention is applied to a lead-acid battery 1 conforming to the EN standard and its battery case 2 has been exemplified, it may also be applied to a lead-acid battery other than the EN standard and its battery case. Further, the position of the narrow portion 31 does not necessarily have to be limited to the lower part of the battery case. The range of the third rib 25 may be appropriately set according to the position of the narrow portion 31.

Explanation of Signs

[0045] 1 Lead-acid battery 2 Battery case 2A Bottom plate 2B First side wall (side wall on the long side of the battery case) 2C Second side wall (side wall on the short side of the battery case) 5 Electrode plate group 5X Electrode plate 11 Partition wall 12 Cell compartment 21 Vertical rib 21A First vertical rib 21B Second vertical rib 31 Narrow portion 35 Third rib (electrode plate end contact rib)

Claims

1. In a lead-acid battery comprising a group of electrode plates formed by laminating a plurality of electrode plates and separators, and a battery case for housing the group of electrode plates, the battery case has a rectangular plate-shaped bottom plate, the long side of the bottom plate extends in the stacking direction of the group of electrode plates, and the short side of the bottom plate extends in the width direction of the electrode plates, the battery case has a pair of opposing surfaces having ribs that contact the electrode plates located at both ends in the stacking direction of the group of electrode plates, and a width-reduced portion that locally narrows the internal space toward the inner side in the width direction of the group of electrode plates, the ribs include vertical ribs that extend in the vertical direction with a space in the width direction of the electrode plates, and electrode plate end contact ribs that contact both ends in the width direction of the electrode plates within the height range of the width-reduced portion, and the contact surfaces thereof extend outward in the width direction from both ends in the width direction along the surface of the electrode plates, a lead-acid battery characterized by the above.

2. The lead-acid battery according to claim 1, wherein the electrode plate end contact ribs extend from the inner surface of the side wall on the long side of the bottom plate by at least 1 / 5 of the distance from the inner surface to the vertical ribs located at both ends in the width direction of the electrode plates.

3. The lead-acid battery according to claim 2, wherein the electrode plate end contact ribs are connected to any of the vertical ribs.

4. The lead-acid battery according to any one of claims 1 to 3, wherein the electrode plate end contact ribs are provided with a space in the width direction and contact the corners at both ends in the width direction of the electrode plates respectively.

5. The lead-acid battery according to any one of claims 1 to 4, wherein the electrode plate end contact ribs are connected to both ends in the width direction of the electrode plates and the bottom plate of the battery case.

6. The lead-acid battery according to any one of claims 1 to 5, wherein the electrode plate end contact ribs are not formed above the width-reduced portion.

7. In a battery case for a lead-acid battery that houses a group of electrode plates formed by laminating a plurality of electrode plates and separators, the battery case has a rectangular plate-shaped bottom plate, the long side of the bottom plate extends in the stacking direction of the group of electrode plates, and the short side of the bottom plate extends in the width direction of the electrode plates, the battery case has a pair of opposing surfaces having ribs that contact the electrode plates located at both ends in the stacking direction of the group of electrode plates, and a width-reduced portion that locally narrows the internal space toward the inner side in the width direction of the group of electrode plates, The rib includes a vertical rib extending in the vertical direction with a space in the width direction of the electrode plate, and electrode plate both-end contact ribs that contact both ends in the width direction of the electrode plate within the range of the height of the narrow-width portion, and the contact surfaces thereof extend outward in the width direction from both ends in the width direction along the surface of the electrode plate. A battery cell characterized by the above.

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