Lead-acid battery

Abstract

DEPCT64 A lead-acid battery (100) consisting of a lid (14) and a linkage chamber (520) was made in the inner part of The lid (14) in the connecting chamber (520) is the distance between the inner wall (432) and the air vent (321). The side wall (506,522) is shorter than the second distance between the inner wall (432) and the connecting hole (328,330). The outermost end (432A) of the other side of the first direction, at the inner wall (432), is prepared at The position of the other side of the first direction is greater than the air passage hole(321). The image chosen is image number 7. -----------------------------------------------------------

Description

Lead-acid battery

[0001] The technology disclosed in this specification relates to a lead-acid battery.

[0002] A lead-acid battery is mounted on a vehicle such as an automobile, for example, and is used as a power source for the vehicle or a power supply source for electrical components mounted on the vehicle. Such a lead-acid battery includes a battery case having an opening and formed with a plurality of cell chambers arranged in a predetermined direction inside, a lid joined to the opening of the battery case, and electrode plate groups disposed in each cell chamber.

[0003] In a lead-acid battery, for example, gas (oxygen gas and hydrogen gas) is generated from the electrode plates in the battery case during charging, the internal pressure of the cell chamber rises, and there is a risk that the battery case or the like may be deformed. Therefore, conventionally, a lead-acid battery having a gas exhaust structure for exhausting the gas generated in the battery case to the outside of the lead-acid battery is provided in the lid. Specifically, the lid includes a lower structure body joined to the opening of the battery case and an upper structure body disposed on the lower structure body, and a chamber and a passage are formed between the lower structure body and the upper structure body. The chamber is formed with an exhaust opening communicating with the cell chamber of the battery case and a chamber outlet communicating with the passage. The passage extends from the chamber outlet to an outlet formed on the outer surface of the lid. The gas generated in the cell chamber is exhausted to the outside of the lead-acid battery through the exhaust opening, the chamber, the passage, and the outlet (see, for example, Patent Document 1 below).

[0004] Japanese Patent Laid-Open No. 57-143261

[0005] By the way, a lead-acid battery may be in an inverted posture in which the lid and the battery case are turned upside down due to, for example, a fall during transportation. In a conventional lead-acid battery having a lid with the above-described gas exhaust structure, when the lead-acid battery is in an inverted posture, the electrolyte in the cell chamber may flow into the communication chamber (chamber) and flow out from the communication chamber to the passage. When the electrolyte flows out of the communication chamber, the possibility of the electrolyte leaking out of the lead-acid battery increases.

[0006] This specification discloses a technology capable of suppressing the outflow of the electrolyte to the outside of the communication chamber when the lead-acid battery is in an inverted posture.

[0007] The lead-acid battery disclosed herein comprises a battery case having an opening on one side in a first direction and having a housing chamber formed in communication with the opening; a positive electrode and a negative electrode housed in the housing chamber of the battery case; and a lid positioned to close the opening of the battery case and having an outlet formed on its outer surface, wherein a communication chamber is formed inside the lid, surrounded by a partition wall between the lid and the housing chamber, opposing walls facing each other in the first direction from the partition wall, and side walls connecting the partition wall and the opposing walls, A communication hole is formed in the partition wall that communicates with the containment chamber, and a ventilation hole is formed in the side wall that communicates with the discharge port of the lid. The communication chamber is provided with an inner wall positioned opposite the ventilation hole, and the first distance between the inner wall and the ventilation hole in the side wall is shorter than the second distance between the inner wall and the communication hole. The other end of the inner wall in the first direction is formed at a position on the other side of the ventilation hole in the first direction.

[0008] This is a perspective view showing the external configuration of the lead-acid battery 100 in this embodiment. This is an explanatory diagram showing the YZ cross-sectional configuration of the lead-acid battery 100 at position II-II in Figure 1. This is an explanatory diagram showing the YZ cross-sectional configuration of the lead-acid battery 100 at position III-III in Figure 1. This is an explanatory diagram showing the XY planar configuration of the inner cover 300 viewed from above (top cover 400 side). This is an XY planar configuration diagram showing the top cover 400 viewed from below (inner cover 300). This is a perspective view showing the correspondence between the internal configurations of the inner cover 300 and the top cover 400. This is an explanatory diagram showing the XZ cross-sectional configuration of the cover 14 at position VII-VII in Figure 6. This is an XY planar view showing the configuration of the upper surface of the inner cover 300. This is a perspective view showing the configuration of the lower surface of the top cover 400. This is an explanatory diagram showing the change in the water level of the electrolyte 18 in the cell communication chamber 520 when the lead-acid battery 100 is in an inverted position.

[0009] The technologies disclosed herein can be implemented in the following forms:

[0010] (1) The lead-acid battery disclosed herein comprises a battery case having an opening on one side in a first direction and having a housing chamber formed in communication with the opening; a positive electrode and a negative electrode housed in the housing chamber of the battery case; and a lid positioned to close the opening of the battery case and having an outlet formed on its outer surface, wherein a communication chamber is formed inside the lid, surrounded by a partition wall between the lid and the housing chamber, opposing walls facing each other in the first direction from the partition wall, and side walls connecting the partition wall and the opposing walls. The partition wall has a communication hole that communicates with the housing chamber, and the side wall has a ventilation hole that communicates with the outlet of the lid. The communication chamber is provided with an inner wall positioned opposite the ventilation hole, and the first distance between the inner wall and the ventilation hole in the side wall is shorter than the second distance between the inner wall and the communication hole. The other end of the inner wall in the first direction is formed at a position on the other side of the ventilation hole in the first direction. When the lead-acid battery is in an inverted position, the electrolyte in the battery case flows into the communication chamber through the communication hole formed in the partition wall of the communication chamber, causing the electrolyte level in the communication chamber to rise. When the electrolyte level reaches the ventilation hole formed in the side wall of the communication chamber, there is a risk that the electrolyte will flow out of the communication chamber through the ventilation hole. Here, if the tip of the inner wall is positioned on one side of the first direction (opposite to the battery case) from at least a part of the vent hole, or if the distance between the inner wall and the vent hole is greater than the distance between the inner wall and the communication hole, the electrolyte is likely to flow out of the communication chamber. In other words, in these configurations, there is no obstacle preventing air from outside the communication chamber from flowing into the communication chamber through the vent hole. Therefore, air from outside the communication chamber easily enters the communication chamber through the vent hole. As a result, the electrolyte is likely to flow out of the communication chamber due to gas-liquid exchange inside and outside the communication chamber. In contrast, in this lead-acid battery, the communication chamber is provided with an inner wall positioned near the vent hole and facing the vent hole, and the tip of the inner wall on the other side of the first direction (the battery case side) is formed at a position on the other side of the first direction from the vent hole. Therefore, outside air from the communication chamber is less likely to enter the chamber through the ventilation holes, and gas-liquid exchange between the inside and outside of the communication chamber is suppressed.This prevents the electrolyte from leaking out of the communication chamber when the lead-acid battery is in an inverted position.

[0011] (2) In the lead-acid battery described above, the inner wall may be configured as a cylindrical exhaust pipe wall that protrudes from the opposing wall toward the communication hole. When the lead-acid battery is in an inverted position, the electrolyte in the battery case flows into the exhaust pipe wall located in the communication chamber through the communication hole. After the exhaust pipe wall is filled with electrolyte, the electrolyte in the exhaust pipe wall overflows onto the opposing wall of the communication chamber. Subsequently, when the electrolyte level outside the exhaust pipe wall in the communication chamber becomes the same as the electrolyte level inside the exhaust pipe wall, the rate at which the electrolyte level rises in the communication chamber slows down. Here, if the tip of the exhaust pipe wall is formed at a position on one side in the first direction (opposite side from the battery case) from at least a portion of the ventilation hole, a large amount of electrolyte will flow out of the communication chamber. In other words, in such a configuration, during the low-water-level period when the rate of rise of the electrolyte level is slow, a continuous space exists within the communication chamber, extending from the vent hole to the communication hole. This continuous space promotes gas-liquid exchange between the inside and outside of the communication chamber, causing a large amount of electrolyte to flow out of the communication chamber. In contrast, in this lead-acid battery, the tip of the exhaust pipe wall is formed on the other side (towards the battery case) of the first direction from the vent hole. Therefore, when the electrolyte levels inside and outside the exhaust pipe wall become the same, the vent hole is already blocked by the electrolyte, making it difficult for air from outside the communication chamber to enter the communication chamber through the vent hole. As a result, gas-liquid exchange between the inside and outside of the communication chamber is less likely to occur during the low-water-level period, and the outflow of electrolyte to the outside of the communication chamber is suppressed. In other words, with this lead-acid battery, the outflow of electrolyte to the outside of the communication chamber can be suppressed more effectively when the lead-acid battery is in an inverted position.

[0012] (3) In the lead-acid battery described above, the communication hole may include an exhaust hole that communicates with the housing chamber and a return hole located on the other side in the first direction from the exhaust hole and communicating with the housing chamber, and the vent hole may be formed in the communication chamber at a position closer to the exhaust hole than to the return hole. In a configuration in which an exhaust hole and a return hole located on the other side (cell side) in the first direction from the exhaust hole are formed in the communication chamber, when the lead-acid battery is in an inverted position, the water level of the electrolyte in the communication chamber reaches the exhaust hole before the return hole. As a result, the exhaust hole is blocked by the electrolyte and the return hole is left open. If the vent hole is formed at a position closer to the return hole than to the exhaust hole, a large amount of electrolyte will flow out of the communication chamber. In other words, even if the electrolyte level in the communication chamber reaches the exhaust port, a continuous space exists within the communication chamber from the vent to the return port. This continuous space promotes gas-liquid exchange between the inside and outside of the communication chamber, causing a large amount of electrolyte to flow out of the communication chamber. In contrast, in this lead-acid battery, the vent is located closer to the exhaust port than the return port. Therefore, when the lead-acid battery is in an inverted position and the electrolyte level in the communication chamber reaches the exhaust port, electrolyte accumulated in the communication chamber exists between the vent and the return port. In other words, a continuous space is not formed within the communication chamber from the vent to the return port. As a result, gas-liquid exchange between the inside and outside of the communication chamber is suppressed. Thus, with this lead-acid battery, the outflow of electrolyte to the outside of the communication chamber can be suppressed more effectively when the lead-acid battery is in an inverted position.

[0013] A. Embodiment: A-1. Configuration: (Configuration of lead-acid battery 100) Figure 1 is a perspective view showing the external configuration of the lead-acid battery 100 in this embodiment, Figure 2 is an explanatory diagram showing the YZ cross-sectional configuration of the lead-acid battery 100 at position II-II in Figure 1, and Figure 3 is an explanatory diagram showing the YZ cross-sectional configuration of the lead-acid battery 100 at position III-III in Figure 1. Note that in Figures 2 and 3, for convenience, the configuration of the electrode plate group 20, which will be described later, is represented in a form different from the actual configuration in order to make it easier to understand. Each figure shows mutually orthogonal XYZ axes for specifying the direction. In this specification, for convenience, the positive Z-axis direction is referred to as the "upward direction" and the negative Z-axis direction is referred to as the "downward direction," but the lead-acid battery 100 may actually be installed in a direction different from such orientations. Furthermore, the vertical direction (Z-axis direction) corresponds to the first direction in the claims, the upward direction (positive Z-axis direction) corresponds to one side of the first direction in the claims, and the downward direction (negative Z-axis direction) corresponds to the other side of the first direction in the claims.

[0014] The lead-acid battery 100 can discharge a large current in a short time and can exhibit stable performance under various conditions. For example, it is installed in vehicles such as automobiles and used as a power source for the starter when starting the engine and as a power source for various electrical components such as lights. As shown in Figures 1 to 3, the lead-acid battery 100 comprises a housing 10, a positive electrode terminal section 30, a negative electrode terminal section 40, and a plurality of electrode plate groups 20. Hereinafter, the positive electrode terminal section 30 and the negative electrode terminal section 40 will be collectively referred to as "terminal sections 30 and 40".

[0015] (Configuration of the housing 10) The housing 10 has a battery case 12 and a lid 14. The battery case 12 is a roughly rectangular container with an opening on its top surface, and is made of, for example, synthetic resin. The lid 14 is a member positioned to close the opening of the battery case 12, and is made of, for example, synthetic resin. The peripheral edge of the lower surface of the lid 14 and the peripheral edge of the opening of the battery case 12 are joined, for example, by heat welding, thereby forming an airtight space inside the housing 10 that is protected from the outside. The space inside the housing 10 is divided by a partition wall 58 into a plurality of (for example, six) cell chambers (storage chambers) 16 arranged in a predetermined direction (in this embodiment, the X-axis direction). Hereinafter, the direction in which the plurality of cell chambers 16 are arranged (the X-axis direction) will be referred to as the "cell arrangement direction". Furthermore, as shown in Figure 1, the orientation of the lead-acid battery 100 when the lid 14 is positioned above the battery case 12 is called the "normal orientation," and the orientation of the lead-acid battery 100 when the lid 14 is positioned below the battery case 12 (the orientation of the lead-acid battery 100 inverted as shown in Figure 1) is called the "inverted orientation." In the following explanation, unless otherwise specified, it will be assumed that the lead-acid battery 100 is in the normal orientation. The detailed configuration of the lid 14 will be described later.

[0016] Each cell chamber 16 within the housing 10 houses one electrode plate group 20. Therefore, for example, if the space within the housing 10 is divided into six cell chambers 16, the lead-acid battery 100 will have six electrode plate groups 20. Each cell chamber 16 within the housing 10 also houses an electrolyte 18 containing dilute sulfuric acid, and the entire electrode plate group 20 is immersed in the electrolyte 18. The electrolyte 18 is injected into the cell chamber 16 through an injection hole 311 provided in the lid 14, which will be described later.

[0017] (Configuration of the electrode plate group 20) The electrode plate group 20 comprises a plurality of positive electrode plates 210, a plurality of negative electrode plates 220, and a separator 230. The plurality of positive electrode plates 210 and the plurality of negative electrode plates 220 are arranged so that the positive electrode plates 210 and negative electrode plates 220 are arranged alternately. Hereinafter, the positive electrode plates 210 and the negative electrode plates 220 will be collectively referred to as "electrode plates 210, 220".

[0018] The positive electrode plate 210 comprises a positive electrode current collector 212 and a positive electrode active material 216 supported by the positive electrode current collector 212. The positive electrode current collector 212 is a conductive member having bones arranged in a substantially grid or mesh pattern, and is formed of, for example, lead or a lead alloy. The positive electrode current collector 212 also has positive electrode lugs 214 projecting upward near its upper end. The positive electrode active material 216 contains lead dioxide. The positive electrode active material 216 may further contain known additives.

[0019] The negative electrode plate 220 comprises a negative electrode current collector 222 and a negative electrode active material 226 supported by the negative electrode current collector 222. The negative electrode current collector 222 is a conductive member having bones arranged in a substantially grid or mesh pattern, and is formed of, for example, lead or a lead alloy. The negative electrode current collector 222 also has a negative electrode lug portion 224 projecting upward near its upper end. The negative electrode active material 226 contains lead. The negative electrode active material 226 may further contain known additives.

[0020] The separator 230 is made of an insulating material (for example, glass or synthetic resin). The separator 230 is positioned between adjacent positive electrode plates 210 and negative electrode plates 220. The separator 230 may be configured as a single integrated component, or as a collection of multiple components provided for each combination of positive electrode plates 210 and negative electrode plates 220.

[0021] The positive electrode lugs 214 of the multiple positive electrode plates 210 constituting the electrode plate group 20 are connected to a positive electrode-side strap 52 made of, for example, lead or a lead alloy. That is, the multiple positive electrode plates 210 are electrically connected in parallel via the positive electrode-side strap 52. Similarly, the negative electrode lugs 224 of the multiple negative electrode plates 220 constituting the electrode plate group 20 are connected to a negative electrode-side strap 54 made of, for example, lead or a lead alloy. That is, the multiple negative electrode plates 220 are electrically connected in parallel via the negative electrode-side strap 54. Hereinafter, the positive electrode-side strap 52 and the negative electrode-side strap 54 will be collectively referred to as "straps 52 and 54".

[0022] In the lead-acid battery 100, the negative electrode strap 54 housed in one cell chamber 16 is connected to the positive electrode strap 52 housed in another cell chamber 16 adjacent to the first cell chamber 16 on one side (for example, the positive X-axis side) via a connecting member 56 made of, for example, lead or a lead alloy. The positive electrode strap 52 housed in the first cell chamber 16 is connected to the negative electrode strap 54 housed in another cell chamber 16 adjacent to the second cell chamber 16 on the other side (for example, the negative X-axis side) via a connecting member 56. In other words, the multiple electrode plate groups 20 of the lead-acid battery 100 are electrically connected in series via the straps 52, 54 and the connecting member 56. Note that, as shown in Figure 2, the positive electrode strap 52 housed in the cell chamber 16 located at the end of one side (negative X-axis side) in the cell arrangement direction is connected to a positive electrode column 34, which will be described later, rather than to a connecting member 56. Furthermore, as shown in Figure 3, the negative electrode strap 54 housed in the cell chamber 16 located at the other end (positive X-axis direction) in the cell arrangement direction is connected to the negative electrode column 44, which will be described later, rather than to the connecting member 56.

[0023] (Configuration of terminals 30 and 40) The positive terminal 30 is located near the end of one side (negative X-axis direction) in the cell arrangement direction of the housing 10, and the negative terminal 40 is located near the end of the other side (positive X-axis direction) in the cell arrangement direction of the housing 10.

[0024] As shown in Figure 2, the positive electrode terminal section 30 includes a positive electrode bushing 32 and a positive electrode column 34. The positive electrode bushing 32 is a substantially cylindrical conductive member with a hole that penetrates vertically, and is made of, for example, a lead alloy. The lower portion of the positive electrode bushing 32 is embedded in the lid 14 by insert molding, and the upper portion of the positive electrode bushing 32 protrudes upward from the upper surface of the lid 14. The positive electrode column 34 is a substantially cylindrical conductive member, made of, for example, a lead alloy. The positive electrode column 34 is inserted into the hole in the positive electrode bushing 32. The upper end of the positive electrode column 34 is located at approximately the same position as the upper end of the positive electrode bushing 32 and is joined to the positive electrode bushing 32 by, for example, welding. The lower end of the positive electrode column 34 protrudes downward from the lower end of the positive electrode bushing 32, and further protrudes downward from the lower surface of the cover 14. As described above, it is connected to the positive electrode strap 52 housed in the cell chamber 16 located at one end (negative X-axis direction) in the cell arrangement direction.

[0025] As shown in Figure 3, the negative electrode terminal section 40 includes a negative electrode bushing 42 and a negative electrode column 44. The negative electrode bushing 42 is a substantially cylindrical conductive member with a hole that penetrates vertically, and is made of, for example, a lead alloy. The lower part of the negative electrode bushing 42 is embedded in the lid 14 by insert molding, and the upper part of the negative electrode bushing 42 protrudes upward from the upper surface of the lid 14. The negative electrode column 44 is a substantially cylindrical conductive member, made of, for example, a lead alloy. The negative electrode column 44 is inserted into the hole in the negative electrode bushing 42. The upper end of the negative electrode column 44 is located at approximately the same position as the upper end of the negative electrode bushing 42 and is joined to the negative electrode bushing 42 by, for example, welding. The lower end of the negative electrode column 44 protrudes downward from the lower end of the negative electrode bushing 42, and further protrudes downward from the lower surface of the cover 14. As described above, it is connected to the negative electrode strap 54 housed in the cell chamber 16 located at the other end (positive X-axis direction) in the cell arrangement direction.

[0026] During discharge of the lead-acid battery 100, a load (not shown) is connected to the positive electrode bushing 32 of the positive electrode terminal section 30 and the negative electrode bushing 42 of the negative electrode terminal section 40, and the power generated by the reaction at the positive electrode plate 210 of each electrode plate group 20 (a reaction in which lead sulfate is produced from lead dioxide) and the reaction at the negative electrode plate 220 (a reaction in which lead sulfate is produced from lead) is supplied to the load. During charging of the lead-acid battery 100, a power source (not shown) is connected to the positive electrode bushing 32 of the positive electrode terminal section 30 and the negative electrode bushing 42 of the negative electrode terminal section 40, and the power supplied from the power source causes the reaction at the positive electrode plate 210 of each electrode plate group 20 (a reaction in which lead dioxide is produced from lead sulfate) and the reaction at the negative electrode plate 220 (a reaction in which lead sulfate is produced from lead) to occur, thereby charging the lead-acid battery 100.

[0027] A-2. Detailed configuration of lid 14: As shown in Figures 2 and 3, the lid 14 is a so-called double-lid structure, comprising an inner lid 300 and an upper lid 400. An internal space of the lid 14 is formed between the inner lid 300 and the upper lid 400. Figure 4 is an explanatory diagram showing the XY planar configuration of the inner lid 300 as viewed from above (upper lid 400 side), and Figure 5 is an XY planar configuration diagram showing the upper lid 400 as viewed from below (inner lid 300). Figure 6 is a perspective view showing the internal configuration of the inner lid 300 and the upper lid 400. However, in Figure 6, for convenience, the upper lid 400 is shown separated from the inner lid 300, and only the parts of the inner lid 300 and the upper lid 400 that constitute one compartment 500 are shown. Figure 7 is an explanatory diagram showing the XZ cross-sectional configuration of the lid 14 at the position VII-VII in Figure 6. However, Figure 7 shows the XZ cross-sectional configuration of the lid 14 when the upper lid 400 shown in Figure 6 is placed on top of the inner lid 300.

[0028] A-2-1. Internal space of lid 14: The internal space of lid 14 is divided by partition walls 506 into multiple compartments 500 (the same number as the number of cell chambers 16) arranged in the direction of the cell arrangement. Each compartment 500 corresponds to one of the multiple cell chambers 16 and is located directly above the corresponding cell chamber 16. A detailed explanation follows below.

[0029] Specifically, as shown in Figures 2 to 4 and Figure 6, the inner lid 300 has a flat inner lid body 302, an inner lid peripheral wall 304, and a plurality of inner lid partitions 306 (one less than the number of cell chambers 16). The inner lid peripheral wall 304 is located on the upper surface of the inner lid body 302 in a direction substantially perpendicular to the cell arrangement direction (X-axis direction) (Y-axis direction, hereinafter referred to as the "depth direction"), in a region opposite to the terminal portions 30 and 40. The inner lid peripheral wall 304 is formed to protrude upward from the upper surface of the inner lid body 302. The shape of the inner lid peripheral wall 304 when viewed in the vertical direction (Z-axis direction) is a substantially rectangular frame shape. The plurality of inner lid partitions 306 are arranged within the inner lid peripheral wall 304 at predetermined intervals in the cell arrangement direction. Each inner lid partition 306 extends along the depth direction, and both ends of each inner lid partition 306 in the depth direction are connected to the inner circumferential surface of the inner lid circumferential wall 304 (see Figure 4).

[0030] On the other hand, as shown in Figures 2, 3, 5, and 6, the top cover 400 has a flat top cover body 402, a top cover peripheral wall 404, and a plurality of top cover partitions 406 (one less than the number of cell chambers 16). The top cover peripheral wall 404 is formed to protrude downward from the lower surface of the top cover body 402. The shape of the top cover peripheral wall 404 when viewed in the vertical direction (view in the Z-axis direction) is a substantially rectangular frame shape that extends along the peripheral edge of the top cover body 402. In addition, at each of the two ends of the top cover peripheral wall 404 that face each other in the cell arrangement direction (X-axis direction), an outlet 405 is formed that penetrates the top cover peripheral wall 404. The plurality of top cover partitions 406 are arranged at predetermined intervals in the cell arrangement direction. Each upper lid partition 406 extends along the depth direction (Y-axis direction), and both ends of each upper lid partition 406 in the depth direction are connected to the inner surface of the upper lid peripheral wall 404 (see Figure 5). However, each upper lid partition 406 has a first notch 407 opening formed therein. Note that the aforementioned inner lid partitions 306 formed in the inner lid 300 do not have any notches formed therein.

[0031] The inner lid periphery wall 304 and the upper lid periphery wall 404 are joined by heat welding to form a periphery wall 504 that constitutes the outer surface of the lid 14, thereby creating the aforementioned internal space inside the lid 14. In addition, each inner lid partition wall 306 and each upper lid partition wall 406 are joined by heat welding to form partition walls 506, thereby dividing the internal space of the lid 14 into a plurality of compartments 500. The plurality of compartments 500 are in communication with each other via a first notch 407 formed in each upper lid partition wall 406.

[0032] A-2-2. Internal configuration of each compartment 500: Each compartment 500 includes a liquid injection chamber 510, a cell communication chamber 520, and an exhaust passage 530. Furthermore, the compartment 500 located at the end in the cell arrangement direction (X-axis direction) (hereinafter referred to as the "end compartment 500") includes a centralized exhaust chamber 540 (see Figures 2, 3, and 7).

[0033] (Injection Chamber 510) As shown in Figures 2 and 3, the injection chamber 510 is a space for injecting electrolyte 18 into each cell chamber 16 of the battery case 12. Specifically, the injection chamber 510 is a space surrounded by an injection side wall 512, which has a substantially cylindrical shape when viewed in the vertical direction (viewed in the Z-axis direction). As shown in Figures 4 and 6, the injection side wall 312 of the inner lid is formed within the inner lid peripheral wall 304 on the upper surface of the inner lid body 302 so as to protrude upward from the inner lid body 302. The shape of the injection side wall 312 when viewed in the vertical direction is substantially cylindrical. In addition, an injection hole 311 is formed within the injection side wall 312 on the upper surface of the inner lid body 302, penetrating the inner lid body 302 in the vertical direction. Electrolyte 18 can be injected into the cell chamber 16 of the battery case 12 from the injection hole 311. On the other hand, as shown in Figures 5 and 6, within the upper lid peripheral wall 404 on the lower surface of the upper lid body 402, the upper lid liquid injection side wall 412 is formed so as to protrude downward from the upper lid body 402 at a position opposite to the inner lid liquid injection side wall 312. The shape of the upper lid liquid injection side wall 412 when viewed in the vertical direction is substantially cylindrical. The liquid injection side wall 512 is formed by joining the inner lid liquid injection side wall 312 and the upper lid liquid injection side wall 412 by heat welding, thereby forming a liquid injection chamber 510 inside the lid 14 (see Figures 2 and 3).

[0034] (Cell Communication Chamber 520) The cell communication chamber 520 is a space that communicates with the cell chamber 16 through communication holes (exhaust holes 328 and return holes 330, described later) formed therein. Specifically, the cell communication chamber 520 is a space surrounded by a partition wall 506 and an exhaust side wall 522, and the shape of the cell communication chamber 520 when viewed in the vertical direction is approximately trapezoidal. As shown in Figures 4 and 6, within the inner lid peripheral wall 304 on the upper surface of the inner lid body 302, the inner lid exhaust side wall 322, which together with the inner lid partition wall 306 forms an approximately trapezoidal partition wall, is formed so as to protrude upward from the inner lid body 302. On the other hand, as shown in Figures 5 and 6, within the upper lid peripheral wall 404 on the lower surface of the upper lid body 402, an upper lid exhaust side wall 422 is formed to protrude downward from the upper lid body 402, at a position opposite to the middle lid exhaust side wall 322, and together with the upper lid partition wall 406, it forms a roughly trapezoidal partition wall. The middle lid exhaust side wall 322 and the upper lid exhaust side wall 422 are joined by heat welding to form an exhaust side wall 522, thereby forming a cell communication chamber 520 inside the lid 14 (see Figures 2, 3 and 7). However, as shown in Figure 6, a second notch 321 is formed between the middle lid partition wall 306 and the middle lid exhaust side wall 322, and no notch is formed between the upper lid partition wall 406 and the upper lid exhaust side wall 422. Therefore, the cell communication chamber 520 communicates with the exhaust passage 530 via the second notch 321. The cell-connecting cubicle 520 corresponds to the connecting cubicle in the claims, the partition wall 506 and the exhaust side wall 522 correspond to the side wall in the claims, and the second cutout portion 321 corresponds to the ventilation hole in the claims.

[0035] Furthermore, the portion of the inner lid body 302 located inside the inner lid partition wall 306 and the inner lid exhaust side wall 322 when viewed in the vertical direction includes a first partition wall 324, a second partition wall 326, and a stepped portion 325 connecting the first partition wall 324 and the second partition wall 326. The first partition wall 324, the second partition wall 326, and the stepped portion 325 are walls that separate the cell chamber 16 from the cell communication chamber 520. The first partition wall 324 is positioned closer to the second notch portion 321 than the second partition wall 326. As shown in Figure 7, the first partition wall 324 and the second notch portion 321 are spaced apart from each other in the vertical direction (Z-axis direction). In other words, the second notch portion 321 is located above the upper surface of the first partition wall 324. Specifically, a stepped portion 327 is formed between the first partition wall 324 and the second notch 321, extending upward from the first partition wall 324. As a result, the first partition wall 324 and the second notch 321 are spaced apart from each other in the vertical direction. Furthermore, the second notch 321 and the lower surface of the top lid body 402 are also spaced apart from each other in the vertical direction. In other words, the second notch 321 is located below the lower surface of the top lid body 402.

[0036] Furthermore, the first partition wall 324 has an exhaust hole 328 that penetrates the first partition wall 324 in the vertical direction. Also, on the upper surface of the first partition wall 324, a substantially cylindrical connecting pipe portion 332 is formed, surrounding the exhaust hole 328 and extending upward from the first partition wall 324. The upper tip 332A of the connecting pipe portion 332 is located above the upper surface of the inner lid partition wall 306 and the upper surface of the inner lid exhaust side wall 322, and reaches inside the top lid 400 (see Figure 7).

[0037] As described above, the second partition wall 326 is positioned further away from the second notch 321 than the first partition wall 324. Furthermore, the second partition wall 326 is located below the first partition wall 324 (towards the electrode plate group 20) via a vertically extending stepped portion 325. The second partition wall 326 has a recirculation hole 330 that penetrates it vertically. That is, the recirculation hole 330 is positioned closer to the electrolyte 18 surface than the exhaust hole 328. The first partition wall 324 is inclined diagonally downward toward the second partition wall 326, and the second partition wall 326 is inclined toward the recirculation hole 330 (see Figure 7). As a result, when the lead-acid battery 100 is in its normal position, the electrolyte 18 remaining in the cell communication chamber 520 can be smoothly guided to the recirculation hole 330 along the inclination of the first partition wall 324 and the second partition wall 326, and returned to the cell chamber 16. The exhaust hole 328 and the recirculation hole 330 correspond to the communication holes in the claims. In addition, the portion of the top cover body 402 facing the first partition wall 324 and the second partition wall 326 corresponds to the opposing wall in the claims.

[0038] As shown in Figures 6 and 7, an exhaust pipe wall 432 is formed on the lower surface of the upper lid body 402, at a position opposite to the exhaust hole 328 formed in the first partition wall 324 of the inner lid body 302, so as to protrude downward from the upper lid body 402. The shape of the exhaust pipe wall 432 in a vertical view (view in the Z-axis direction) is approximately rectangular. The lower tip portion 432A of the exhaust pipe wall 432 is located below the second notch portion 321. Furthermore, the tip portion 432A of the exhaust pipe wall 432 is located below the upper tip portion 332A of the communication pipe portion 332 of the inner lid 300, and the exhaust pipe wall 432 is arranged to surround the communication pipe portion 332 of the inner lid 300. The exhaust pipe wall 432 corresponds to the inner wall in the claims, and the tip portion 432A of the exhaust pipe wall 432 corresponds to the other tip portion in the first direction of the inner wall in the claims.

[0039] Figure 8 is an XY plan view showing the configuration of the upper surface of the inner lid 300. In Figure 8, the exhaust pipe wall 432 formed on the upper lid 400 is shown by a dashed line. As shown in Figure 8, a part of the exhaust pipe wall 432 faces the second notch 321 (ventilation hole) formed in the cell communication chamber 520. Furthermore, the first distance L1, which is the shortest distance between the exhaust pipe wall 432 and the hole-forming portion where the second notch 321 is formed (the notch between the upper lid partition wall 406 and the upper lid exhaust side wall 422), is shorter than the second distance L2, which is the shortest distance between the exhaust pipe wall 432 and the portion where the exhaust hole 328 is formed (communication pipe portion 332) (see Figure 7). The first distance L1 is preferably 3 mm or less, and more preferably 2 mm or less. In this embodiment, the first distance L1 is 1.5 mm. Furthermore, the tip portion 432A of the exhaust pipe wall 432 is located below the entirety of the second notch 321 (towards the cell chamber 16). Also, the width of the second notch 321 in at least one direction (for example, the width in the direction perpendicular to the vertical direction) is preferably 3 mm or less, and more preferably 2 mm or less. In this embodiment, the width of the second notch 321 is 1.5 mm.

[0040] Figure 9 is a perspective view showing the configuration of the lower side of the top cover 400. Also, as shown in Figures 6 and 9, an internal flow path Q is formed between the exhaust pipe wall 432 and the exhaust side wall 522 (top cover partition wall 406, top cover exhaust side wall 422), communicating with the second notch 321 and located on the cell chamber 16 side of the second notch 321. The distance between the opposing surfaces of the exhaust pipe wall 432 and the exhaust side wall 522 that form this internal flow path Q is preferably 3 mm or less, and more preferably 2 mm or less. In this embodiment, the opposing distance is 1.5 mm.

[0041] Furthermore, as shown in Figures 6 and 9, at least a portion of the surface of the opposing surfaces of the exhaust pipe wall 432 and the exhaust side wall 522 has an uneven surface T. Specifically, of the four outer surfaces of the exhaust pipe wall 432, the outer surface on the side of the recirculation hole 330 is a substantially flat surface, while the remaining three outer surfaces have multiple uneven surfaces T. Also, of the inner circumferential surfaces of the inner lid partition wall 306 and the inner lid exhaust side wall 322 that constitute the exhaust side wall 522, the portions facing the remaining three outer surfaces of the exhaust pipe wall 432 have multiple uneven surfaces T. Note that the remaining three outer surfaces of the exhaust pipe wall 432 and the exhaust side wall 522 (inner lid partition wall 306, inner lid exhaust side wall 322) face each other via a distance approximately equal to the width of the second notch 321, and constitute an internal flow path Q. More specifically, on the opposing surfaces of the exhaust pipe wall 432 and the exhaust side wall 522, a plurality of protrusions T extending in the vertical direction (Z-axis direction) are arranged parallel to the opposing surfaces and in a direction substantially perpendicular to the vertical direction. Preferably, the height difference between the peaks and valleys of the protrusions T is 0.1 mm or more. Furthermore, the surface of the partition wall (first partition wall 324, second partition wall 326) on the upper cover 400 side, where the second notch 321 is formed, does not have protrusions T formed and is substantially flat.

[0042] (Centralized Exhaust Chamber 540) As shown in Figures 2 and 3, the centralized exhaust chamber 540 is located within each end compartment 500, between the liquid injection chamber 510 and the cell communication chamber 520. The centralized exhaust chamber 540 is a space surrounded by the centralized exhaust side wall 542, and its shape in the vertical view is approximately circular. Specifically, as shown in Figures 4 and 6, the upper surface of the inner lid body 302 has a roughly arc-shaped inner lid centralized exhaust side wall 342 with a third notch 341 formed on the inner lid liquid injection side wall 312 side, projecting upward from the inner lid body 302. On the other hand, as shown in Figures 5 and 6, the lower surface of the upper lid body 402 has a roughly cylindrical upper lid centralized exhaust side wall 442 projecting downward from the upper lid body 402 at a position opposite to the inner lid centralized exhaust side wall 342. A duct 443 that communicates with the above-mentioned outlet 405 is formed in the upper lid centralized exhaust side wall 442. The central exhaust side wall 542 is formed by joining the central exhaust side wall 342 of the inner lid and the central exhaust side wall 442 of the upper lid by heat welding, thereby forming a central exhaust chamber 540 inside the lid 14 (see Figures 2 and 3). A filter (not shown) is also placed in the central exhaust chamber 540, and gas G that enters the central exhaust side wall 342 of the inner lid from the exhaust passage 530 through the third notch 341 enters the central exhaust side wall 442 of the upper lid through the filter and is discharged to the outside of the lead-acid battery 100 (lid 14) through the outlet 405.

[0043] (Exhaust passage 530) As shown in Figure 6, the exhaust passage 530 communicates with the cell communication chamber 520 via the second notch 321 and also communicates with the outlet 405. Specifically, in the end compartment 500, the exhaust passage 530 communicates directly with the central exhaust chamber 540, and further communicates with the outlet 405 via the central exhaust chamber 540. In the end compartment 500, the exhaust passage 530 extends from the second notch 321, curves around the outer circumference of the exhaust side wall 522, passes between the cell communication chamber 520 and the central exhaust chamber 540, and further curves around the outer circumference of the liquid injection chamber 510, reaching the third notch 341 of the central exhaust chamber 540.

[0044] More specifically, as shown in FIGS. 4 and 6, on the upper surface of the inner lid main body 302, a connecting wall 352 that connects the inner lid liquid injection side wall 312 and the inner lid centralized exhaust side wall 342 is formed so as to protrude upward from the inner lid main body 302. As a result, in the inner lid 300, an inner lid exhaust flow path 354 surrounded by the inner lid peripheral wall 304, the inner lid exhaust side wall 322, the inner lid partition wall 306, the inner lid liquid injection side wall 312, and the connecting wall 352 is formed. The bottom surface in the inner lid exhaust flow path 354 of the inner lid main body 302 is flush over the entire length of the inner lid exhaust flow path 354 and is inclined toward the second notch portion 321. Thereby, when the lead storage battery 100 is in the normal posture, the electrolyte 18 that has leaked into the exhaust flow path 530 can be smoothly returned into the cell communication compartment 520 through the bottom surface in the inner lid exhaust flow path 374. That is, the inner lid exhaust flow path 354 is continuously connected over its entire length. A plurality of ribs 356 are formed in the inner lid exhaust flow path 354. These plurality of ribs 356 trap mist (water vapor) contained in the gas G flowing from the second notch portion 321 toward the third notch portion 341 and aggregate it into water. Further, these plurality of ribs 356 suppress the electrolyte 18 flowing out from the cell communication compartment 520 through the second notch portion 321 and flowing toward the discharge port 405 side.

[0045] On the other hand, as shown in Figures 5 and 6, the lower surface of the top lid body 402 is formed such that a first connecting wall 452 connecting the top lid partition wall 406 and the top lid central exhaust side wall 442, a second connecting wall 454 connecting the top lid partition wall 406 and the top lid liquid injection side wall 412, and a third connecting wall 456 connecting the top lid liquid injection side wall 412 and the top lid central exhaust side wall 442 protrude downward from the top lid body 402. No notches are formed in any of the first connecting wall 452, the second connecting wall 454, and the third connecting wall 456. As a result, a first top lid space 460, a second top lid space 462, and a third top lid space 464 are formed within the end compartment 500 of the top lid 400. The first upper lid space 460 is the space enclosed by the upper lid peripheral wall 404, the upper lid exhaust side wall 422, the upper lid concentrated exhaust side wall 442, and the connecting wall 452, and is located closest to the second notch 321. The second upper lid space 462 is the space enclosed by the upper lid partition wall 406, the first connecting wall 452, the second connecting wall 454, and the third connecting wall 456, and is located further from the second notch 321 than the first upper lid space 460. The third upper lid space 464 is the space enclosed by the upper lid peripheral wall 404, the upper lid partition wall 406, the upper lid liquid injection side wall 412, the second connecting wall 454, and the third connecting wall 456, and is located even further from the second notch 321 than the second upper lid space 462. As described above, in the end compartment 500, the exhaust passage 530 is continuously connected on the inner lid 300 side, and on the upper lid 400 side, it is divided into three spaces 460, 462, and 464 by the first connecting wall 452, the second connecting wall 454, and the third connecting wall 456. Furthermore, the total volume of the second upper lid space 462 and the third upper lid space 464 (the volume of electrolyte 18 to be contained) is greater than the volume of the upper lid exhaust side wall 422. Also, the volume of the first upper lid space 460 is greater than the volume of the second upper lid space 462.

[0046] In the compartment 500 (hereinafter referred to as the "inner compartment 500"), which is located inside the end compartment 500 in the cell arrangement direction (X-axis direction) of the multiple compartments 500, the exhaust passage 530 communicates with the central exhaust chamber 540 via the other compartments 500. In the inner compartment 500, the exhaust passage 530 extends from the second notch 321, curves along the outer circumference of the exhaust side wall 522, passes between the cell communication compartment 520 and the central exhaust chamber 540, and reaches the first notch 407 formed in the upper lid partition wall 406.

[0047] More specifically, as shown in Figure 4, the inner lid 300 has an inner lid exhaust passage 374 surrounded by an inner lid peripheral wall 304, an inner lid exhaust side wall 322, an inner lid partition wall 306, and an inner lid liquid injection side wall 312. The bottom surface of the inner lid exhaust passage 374 in the inner lid body 302 is flush with the entire length of the inner lid exhaust passage 374 and is inclined toward the second notch 321. That is, the inner lid exhaust passage 374 is continuously connected along its entire length. As a result, when the lead-acid battery 100 is in its normal position, the electrolyte 18 that has leaked into the exhaust passage 530 can be smoothly returned to the cell communication chamber 520 via the bottom surface of the inner lid exhaust passage 374. In addition, a plurality of ribs 356 are formed in the inner lid exhaust passage 374. These multiple ribs 356 trap mist (water vapor) contained in the gas G flowing from the second notch 321 to the third notch 341, and condense it into water. In addition, these multiple ribs 356 prevent the electrolyte 18 that has flowed out from the cell communication chamber 520 through the second notch 321 to the exhaust passage 530 from flowing towards the first notch 407.

[0048] On the other hand, as shown in FIG. 5, on the lower surface of the upper lid body 402, a fourth connecting wall 472 that connects the upper lid partitions 406 facing each other and a pair of fifth connecting walls 474 that connect the upper lid liquid injection side wall 412 and the upper lid partition 406 are each formed to protrude downward from the upper lid body 402. No notch is formed in either the fourth connecting wall 472 or the fifth connecting wall 474. As a result, a fourth upper lid space 480, a fifth upper lid space 482, and a sixth upper lid space 484 are formed in the inner partition chamber 500 of the upper lid 400. The fourth upper lid space 480 is a space surrounded by the upper lid peripheral wall 404, the upper lid partition 406, the upper lid exhaust side wall 422, and the fourth connecting wall 472, and is arranged at the position closest to the second notch 321. The fifth upper lid space 482 is a space surrounded by the upper lid partition 406, the fourth connecting wall 472, the upper lid liquid injection side wall 412, and the fifth connecting wall 474, and is arranged at a position farther from the second notch 321 than the fourth upper lid space 480. The sixth upper lid space 484 is a space surrounded by the upper lid peripheral wall 404, the upper lid partition 406, the upper lid liquid injection side wall 412, and the fifth connecting wall 474, and is arranged at a position even farther from the second notch 321 than the fifth upper lid space 482. As described above, in the inner partition chamber 500, the exhaust passage 530 is continuously connected on the middle lid 300 side, and on the upper lid 400 side, it is partitioned into three spaces 480, 482, 484 by the fourth connecting wall 472 and the fifth connecting wall 474.

[0049] A-3. Effects of this embodiment: When the lead storage battery 100 is in an inverted posture, the electrolyte 18 in the cell chamber 16 flows into the cell communication individual chamber 520 through the communication holes (exhaust holes 328 and reflux holes 330) formed in the cell communication individual chamber 520, and the water level of the electrolyte 18 in the cell communication individual chamber 520 rises. Then, when the water level of the electrolyte 18 reaches the second notch 321 formed in the cell communication individual chamber 520, there is a risk that the electrolyte 18 will flow out of the cell communication individual chamber 520 (exhaust passage 530) through the second notch 321.

[0050] Here, if the tip portion 432A of the exhaust pipe wall 432 is positioned on the upper lid body 402 side (positive Z-axis direction side) at least a part of the second notch portion 321, or if the distance between the exhaust pipe wall 432 and the second notch portion 321 is greater than the distance between the exhaust pipe wall 432 and the exhaust hole 328 or return hole 330, then the electrolyte 18 is likely to flow out of the cell communication chamber 520. In other words, in these configurations, there is no obstacle preventing the air present in the exhaust passage 530 from flowing into the cell communication chamber 520 through the second notch portion 321. Therefore, the air present in the exhaust passage 530 is likely to enter the cell communication chamber 520 through the second notch portion 321. As a result, when air flows into the cell communication chamber 520 from the exhaust passage 530, the electrolyte 18 flows out from the cell communication chamber 520 into the exhaust passage 530, and at the same time, the electrolyte 18 flows out into the exhaust passage 530 through a so-called gas-liquid exchange.

[0051] In contrast, in the lead-acid battery 100 of this embodiment, the cell communication chamber 520 is provided with an exhaust pipe wall 432 positioned near the second notch 321 and facing the second notch 321. Furthermore, the tip portion 432A of the exhaust pipe wall 432 on the cell chamber 16 side (negative Z-axis direction side) is formed at a position closer to the cell chamber 16 than the second notch 321. As a result, air present in the exhaust passage 530 is less likely to enter the cell communication chamber 520 through the second notch 321, and gas-liquid exchange between the inside and outside of the cell communication chamber 520 is suppressed. Thus, according to this embodiment, when the lead-acid battery 100 is in an inverted position, it is possible to suppress the outflow of electrolyte 18 into the exhaust passage 530 and further to the outside of the housing 10. Next, the effects of this embodiment will be described in more detail.

[0052] Figure 10 is an explanatory diagram showing the change in the water level of the electrolyte 18 in the cell communication chamber 520 when the lead-acid battery 100 is in an inverted position. The XZ cross-sectional configuration of the lid 14 shown in Figure 10 is the same as the XZ cross-sectional configuration of the lid 14 shown in Figure 7, but inverted vertically. As shown in Figure 10, when the lead-acid battery 100 is in an inverted position, the electrolyte 18 in the cell chamber 16 first flows into the exhaust pipe wall 432 through the exhaust hole 328. Then, when the space surrounded by the exhaust pipe wall 432 is filled with the electrolyte 18 (see Figure 10(A)), the electrolyte 18 in the exhaust pipe wall 432 overflows to the outside of the exhaust pipe wall 432 in the cell communication chamber 520 (outside of the exhaust pipe wall 432 in the upper lid body 402). Subsequently, when the water level of the electrolyte 18 outside the exhaust pipe wall 432 in the cell communication chamber 520 reaches the lower end of the second notch 321, the electrolyte 18 begins to flow out of the cell communication chamber 520 through the second notch 321 into the exhaust passage 530. After that, when the water level of the electrolyte 18 outside the exhaust pipe wall 432 in the cell communication chamber 520 becomes the same as the water level of the electrolyte inside the exhaust pipe wall 432 (see Figure 10(B)), the water level of the electrolyte 18 will not rise unless both the inside and outside of the exhaust pipe wall 432 are filled with the electrolyte 18, so the rate at which the water level of the electrolyte 18 in the cell communication chamber 520 rises slows down.

[0053] Here, assuming that the tip portion 432A of the exhaust pipe wall 432 is formed at a position on the upper lid body 402 side (lower side (positive Z-axis direction) in Figure 10) relative to at least a portion of the second notch 321, a large amount of electrolyte 18 will flow out from the cell communication chamber 520 into the exhaust passage 530. In other words, in such a configuration, during the low-water-level period when the rate of rise of the electrolyte 18 is slow, a continuous space extending from the second notch 321 to the recirculation hole 330 exists within the cell communication chamber 520 for a relatively long time, and gas-liquid exchange between the inside and outside of the cell communication chamber 520 is promoted through this continuous space, causing a large amount of electrolyte 18 to flow out from the cell communication chamber 520 into the exhaust passage 530.

[0054] In contrast, in the lead-acid battery 100 of this embodiment, the tip portion 432A of the exhaust pipe wall 432 is formed at a position on the cell chamber 16 side (upper side (negative Z-axis direction side) in Figure 10) relative to the second notch portion 321. Therefore, when the water level of the electrolyte 18 inside and outside the exhaust pipe wall 432 becomes the same, the second notch portion 321 is already blocked by the electrolyte 18, and the continuous space does not exist. As a result, it is difficult for air present in the exhaust passage 530 to enter the cell communication chamber 520 through the second notch portion 321. This makes it difficult for gas-liquid exchange to occur inside and outside the cell communication chamber 520 during the low water level period, and the outflow of electrolyte 18 from the cell communication chamber 520 to the exhaust passage 530 is suppressed. In other words, with the lead-acid battery 100 of this embodiment, when the lead-acid battery 100 is in an inverted position, the outflow of electrolyte 18 from the cell communication chamber 520 to the exhaust passage 530 can be suppressed more effectively.

[0055] Furthermore, in a configuration like the lead-acid battery 100 of this embodiment, where an exhaust port 328 and a recirculation port 330 located on the cell chamber 16 side (negative Z-axis side) of the exhaust port 328 are formed in the cell communication chamber 520, when the lead-acid battery 100 is in an inverted position, the water level of the electrolyte 18 in the cell communication chamber 520 reaches the exhaust port 328 before the recirculation port 330. As a result, the exhaust port 328 is blocked by the electrolyte 18, and the recirculation port 330 is left open. If, hypothetically, the second notch 321 is formed closer to the recirculation port 330 than to the exhaust port 328, a large amount of electrolyte 18 will flow out from the cell communication chamber 520 into the exhaust passage 530. In other words, even if the water level of the electrolyte 18 in the cell communication chamber 520 reaches the exhaust port 328, a continuous space exists within the cell communication chamber 520 that extends continuously from the second notch 321 to the recirculation port 330. Through this continuous space, gas-liquid exchange between the inside and outside of the cell communication chamber 520 is promoted, and a large amount of electrolyte 18 flows out from the cell communication chamber 520 into the exhaust passage 530.

[0056] In contrast, in the lead-acid battery 100 of this embodiment, the second notch 321 is formed closer to the exhaust port 328 than to the recirculation port 330. Therefore, when the lead-acid battery 100 is in an inverted position and the water level of the electrolyte 18 in the cell communication chamber 520 reaches the exhaust port 328, there is electrolyte 18 accumulated in the cell communication chamber 520 between the second notch 321 and the recirculation port 330. In other words, a continuous space extending from the second notch 321 to the recirculation port 330 is not formed within the cell communication chamber 520. Therefore, gas-liquid exchange between the inside and outside of the cell communication chamber 520 is suppressed. As a result, with the lead-acid battery 100 of this embodiment, when the lead-acid battery 100 is in an inverted position, the outflow of electrolyte 18 from the cell communication chamber 520 to the exhaust passage 530 can be suppressed more effectively.

[0057] Furthermore, in the lead-acid battery 100 of this embodiment, at least a portion of the surface of the opposing surfaces of the exhaust pipe wall 432 and the exhaust side wall 522, which communicate with the second notch 321 and form an internal flow path Q located on the cell chamber 16 side (negative Z-axis side) of the second notch 321, has an uneven surface T. As a result, as shown in Figure 10(C), when the lead-acid battery 100 is in an inverted position and the electrolyte 18 in the cell chamber 16 flows into the cell communication chamber 520 and the second notch 321 becomes blocked by the electrolyte 18, the uneven surface T prevents air that has entered the cell communication chamber 520 from the exhaust flow path 530 from moving to the return hole 330. This makes it difficult for gas-liquid exchange to occur inside and outside the cell communication chamber 520, and suppresses the outflow of electrolyte 18 from the cell communication chamber 520 to the exhaust flow path 530.

[0058] Furthermore, in the lead-acid battery 100 of this embodiment, the surface of the partition wall (first partition wall 324, second partition wall 326) on the side facing the upper lid body 402, in which the second notch 321 is formed, is substantially flat, while the surface of the flow path wall (at least a portion of the opposing surfaces of the exhaust pipe wall 432 and the exhaust side wall 522) has an uneven surface T. As a result, compared to the case in which an uneven surface is formed on the partition wall, when the lead-acid battery 100 is returned from an inverted position to a normal position, the electrolyte 18 in the cell communication chamber 520 can be smoothly guided through the partition wall to the recirculation hole 330 and returned to the cell chamber 16.

[0059] Furthermore, in the lead-acid battery 100 of this embodiment, a plurality of connecting walls (452, 454, 472, 474) are formed in the portion of the upper lid body 402 that constitutes the exhaust passage 530. Each connecting wall protrudes from the upper lid body 402 toward the cell chamber 16 and extends continuously across the entire width of the exhaust passage 530 in a direction intersecting the exhaust passage 530. As a result, even if, for example, the lead-acid battery 100 is in an inverted position and the electrolyte 18 in the cell chamber 16 flows into the exhaust passage 530 via the cell communication chamber 520, the electrolyte 18 first remains between the cell communication chamber 520 and each connecting wall. Only after the electrolyte 18 has flowed out to the point of overflowing each connecting wall does it begin to flow from each connecting wall toward the outlet 405. In other words, the lead-acid battery 100 of this embodiment can suppress the flow of electrolyte 18 toward the outlet 405 of the lid 14 compared to a configuration in which no connecting walls are formed in the exhaust passage 530.

[0060] Furthermore, the combined volume of the second upper lid space 462 and the third upper lid space 464 is greater than the volume of the upper lid exhaust side wall 422. As a result, the electrolyte 18 that flows from the cell communication chamber 520 into the exhaust passage 530 has difficulty reaching the third upper lid space 464, which is closest to the outlet 405 formed in the lid 14, thus preventing the electrolyte 18 from leaking out of the lead-acid battery 100 through the outlet 405.

[0061] Furthermore, in the lead-acid battery 100 of this embodiment, the volume of the first upper lid space 460 is larger than the volume of the second upper lid space 462. As a result, compared to a configuration in which the volume of the first upper lid space 460 is smaller than the volume of the second upper lid space 462, the electrolyte 18 that flows out from the cell communication chamber 520 is less likely to overflow the partition wall closest to the cell communication chamber 520, and its approach to the discharge port side of the lid can be suppressed.

[0062] B. Modifications: The technologies disclosed herein are not limited to the embodiments described above, and can be modified in various forms without departing from their essence, for example, the following modifications are possible.

[0063] In the above embodiment, an exhaust pipe wall 432 formed to protrude from the opposing wall (upper lid body 402) constituting the cell communication chamber 520 was exemplified as the internal wall. However, the internal wall may be a wall spaced apart from the opposing wall, or a wall with a shape other than cylindrical, such as a flat plate, as long as it faces the second notch 321.

[0064] In the above embodiment, the lid 14 may not have a connecting cylinder portion 332. Also, in the above embodiment, the lid 14 may be configured such that the second notch portion 321 is formed closer to the recirculation hole 330 than the exhaust hole 328. Also, in the above embodiment, the recirculation hole 330 may not be formed in the cell connecting chamber 520.

[0065] In the above embodiment, the bottom surface of the inner lid body 302 within the inner lid exhaust passage 374 may be flush with the entire length of the inner lid exhaust passage 374 and have a partition wall interposed therein, or it may not be inclined toward the second notch 321.

[0066] In the above embodiment, the uneven portion T may be formed on both opposing surfaces of the exhaust pipe wall 432 and the exhaust side wall 522, or it may be formed on only one surface. Furthermore, the upper surface of the inner lid body 302 may also have the uneven portion T formed on only one or two of the remaining three outer surfaces of the exhaust pipe wall 432. Also, the uneven portion T may not be formed on the opposing surfaces of the exhaust pipe wall 432 and the exhaust side wall 522. Moreover, the uneven portion T is not limited to those extending in a predetermined direction, but may be formed by, for example, hemispherical or columnar protrusions. Furthermore, when the lead-acid battery 100 is in an inverted position and the second notch 321 is blocked by the electrolyte 18, as another configuration to suppress the movement of air that has entered the cell communication chamber 520 from the exhaust passage 530 to the recirculation hole 330, the surface roughness of at least a portion of the opposing surfaces of the exhaust pipe wall 432 and the exhaust side wall 522 may be made greater than the surface roughness of the lower surface of the top cover body 402.

[0067] In the above embodiment, the portion of the top cover body 402 that constitutes the exhaust passage 530 may be divided into two sections, or into four or more sections. Also, the volume of the first top cover space 460 may be smaller than the volume of the second top cover space 462. Furthermore, the combined volume of the second top cover space 462 and the third top cover space 464 may be less than or equal to the volume of the top cover exhaust side wall 422.

[0068] 10: Housing 12: Battery case 14: Lid 16: Cell chamber 18: Electrolyte 20: Electrode plate group 30: Positive electrode terminal section 32: Positive electrode bushing 34: Positive electrode column 40: Negative electrode terminal section 42: Negative electrode bushing 44: Negative electrode column 52: Positive electrode strap 54: Negative electrode strap 56: Connecting member 58: Partition wall 100: Lead-acid battery 210: Positive electrode plate 212: Positive electrode current collector 214: Positive electrode lug 216: Positive electrode active material 220: Negative electrode plate 222: Negative electrode current collector 224: Negative electrode lug 226: Negative electrode active material 230: Separator 300: Inner lid 302: Inner lid body 304: Inner lid peripheral wall 306: Inner lid partition wall 311: Injection hole 312: Inner lid liquid injection side wall 321: Second notch 322: Inner lid exhaust side wall 324: First partition wall 325: Stepped section 326: Second partition wall 327: Stepped section 328: Exhaust hole 330: Recirculation hole 332: Connecting cylinder section 332A: Upper tip 341: Third notch 342: Inner lid concentrated exhaust side wall 352: Connecting wall 354: Inner lid exhaust passage 356: Rib 374: Inner lid exhaust passage 400: Top lid 402: Top lid body 404: Top lid peripheral wall 405: Outlet 406: Top lid partition wall 407: First notch 412: Top lid liquid injection side wall 422: Top lid exhaust side wall 432: Exhaust cylinder wall 432A: Tip section 442: Upper cover central exhaust side wall 443: Duct 452: First connecting wall 454: Second connecting wall 456: Third connecting wall 460: First upper cover space 462: Second upper cover space 464: Third upper cover space 472: Fourth connecting wall 474: Fifth connecting wall 480: Fourth upper cover space 482: Fifth upper cover space 484: Sixth upper cover space 500: Compartment (inner compartment, end compartment) 504: Peripheral wall 506: Partition wall 510: Liquid injection chamber 512: Liquid injection side wall 520: Cell communication chamber 522: Exhaust side wall 530: Exhaust flow path 540: Central exhaust chamber 542: Central exhaust side wall G: Gas L1: First distance L2: Second distance Q: Internal flow path T: Uneven part