Patent Description:
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 source for electrical components mounted on the vehicle. Such a lead-acid battery includes: a container having an opening and having a plurality of cell chambers formed therein in a predetermined direction; a lid joined to the opening of the container; and an electrode group disposed in each cell chamber.

In the lead-acid battery, for example, during charge, gas (oxygen gas or hydrogen gas) is generated from the electrode plate in the container, and internal pressure in the cell chamber increases, which may cause deformation of the container. Therefore, there has been known a lead-acid battery in which a lid is provided with a gas exhaust structure for exhausting gas generated in the container to the outside of the lead-acid battery. Specifically, the lid includes a lower structure joined to the opening of the container and an upper structure disposed on the lower structure, and a chamber and a passage are formed between the lower structure and the upper structure. The chamber is formed with an opening for exhaust communicating with the cell chamber of the container, and a chamber outlet communicating with the passage. The passage extends from the chamber outlet to a discharge port 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, chamber, passage, and discharge port (e.g., see Patent Documents <NUM> and <NUM> below.

The lead-acid battery may be inverted in position where the lid and the container are turned upside down due to, for example, falling during transportation. In the conventional lead-acid battery provided with a lid having the gas exhaust structure described above, when the lead-acid battery is inverted in position, the electrolyte solution in the cell chamber may flow into the communication chamber (chamber) and flow out of the communication chamber into the passage. When the electrolyte solution flows out of the communication chamber, the possibility of the electrolyte solution leaking out of the lead-acid battery increases.

The present specification discloses a technique capable of preventing the outflow of an electrolyte solution to the outside of a communication chamber when a lead-acid battery is in an inverted position.

The present invention provides a lead-acid battery according to claim <NUM>.

The technique disclosed in the present specification can be implemented as the following modes.

<FIG> is a perspective view illustrating an external configuration of a lead-acid battery <NUM> in the present embodiment, <FIG> is an explanatory view illustrating a YZ sectional configuration of the lead-acid battery <NUM> at a position II-II in <FIG>, and <FIG> is an explanatory view illustrating a YZ sectional configuration of the lead-acid battery <NUM> at a position III-III in <FIG>. In <FIG> and <FIG>, for the sake of convenience, the configuration of an electrode group <NUM>, which will be described later, is expressed in a form different from the actual configuration so as to be shown in an easily understandable manner. Each figure illustrates X, Y, and Z-axes orthogonal to each other for specifying directions. In the present specification, for the sake of convenience, the positive Z-axis direction is referred to as an "up direction" and the negative Z-axis direction is referred to as a "down direction," but the lead-acid battery <NUM> may be installed in a direction different from such directions. The vertical direction (Z-axis direction) corresponds to the first direction in the claims, the up direction (positive Z-axis) corresponds to one side in the first direction in the claims, and the down direction (negative Z-axis direction) corresponds to the other side in the first direction in the claims.

Since the lead-acid battery <NUM> can discharge a large current in a short time and can exhibit stable performance under various environments, for example, the lead-acid battery <NUM> is mounted on a vehicle such as an automobile, and is used as a power supply source to a starter at the time of starting an engine or a power supply source to various electrical components such as a light. As illustrated in <FIG>, the lead-acid battery <NUM> includes a housing <NUM>, a positive-side terminal <NUM>, a negative-side terminal <NUM>, and a plurality of electrode groups <NUM>.

Hereinafter, the positive-side terminal <NUM> and the negative-side terminal <NUM> are also collectively referred to as "terminals <NUM>, <NUM>.

The housing <NUM> has a container <NUM> and a lid <NUM>. The container <NUM> is a substantially rectangular parallelepiped case having an opening on its upper surface, and is formed of, for example, synthetic resin. The lid <NUM> is a member disposed so as to close the opening of the container <NUM>, and is formed of, for example, synthetic resin. The peripheral edge of the lower surface of the lid <NUM> and the peripheral edge of the opening of the container <NUM> are joined by, for example, thermal welding, whereby a space kept airtight with the outside is formed in the housing <NUM>. The space in the housing <NUM> is divided by partitions <NUM> into a plurality of (e.g., six) cell chambers (housing chamber) <NUM> arranged in a predetermined direction (the X-axis direction in the present embodiment). Hereinafter, the direction in which the plurality of cell chambers <NUM> are arranged (X-axis direction) is referred to as a "cell arrangement direction. " As illustrated in <FIG> and the like, the position of the lead-acid battery <NUM> when the lid <NUM> is placed on the upper side of the container <NUM> is referred to as "normal position," and the position (vertical inversion of the lead-acid battery <NUM> illustrated in <FIG>, etc.) of the lead-acid battery <NUM> when the lid <NUM> is placed on the lower side of the container <NUM> is referred to as "inverted position. " In the following description, unless otherwise stated, it is assumed that the lead-acid battery <NUM> is in the normal position. A detailed configuration of the lid <NUM> will be described later.

One electrode group <NUM> is housed in each cell chamber <NUM> in the housing <NUM>. Thus, for example, when the space in the housing <NUM> is divided into six cell chambers <NUM>, the lead-acid battery <NUM> includes six electrode groups <NUM>. Further, each cell chamber <NUM> in the housing <NUM> contains an electrolyte solution <NUM> containing dilute sulfuric acid, and the entire electrode group <NUM> is immersed in the electrolyte solution <NUM>. The electrolyte solution <NUM> is injected into the cell chamber <NUM> through a liquid electrolyte solution filling hole <NUM>, described later, provided in the lid <NUM>.

The electrode group <NUM> includes a plurality of positive electrode plates <NUM>, a plurality of negative electrode plates <NUM>, and a separator <NUM>. The plurality of positive electrode plates <NUM> and the plurality of negative electrode plates <NUM> are arranged so that the positive electrode plates <NUM> and the negative electrode plates <NUM> are arranged alternately. Hereinafter, the positive electrode plate <NUM> and the negative electrode plate <NUM> are also collectively referred to as "polar plates <NUM>, <NUM>.

The positive electrode plate <NUM> has a positive current collector <NUM> and a positive active material <NUM> supported by the positive current collector <NUM>. The positive current collector <NUM> is a conductive member having skeletons arranged in substantially the form of a grid or a net, and is formed of, for example, lead or a lead alloy. The positive current collector <NUM> has a positive electrode lug <NUM> protruding upward near the upper end of the positive current collector <NUM>. The positive active material <NUM> contains lead dioxide. The positive active material <NUM> may further include known additives.

The negative electrode plate <NUM> has a negative current collector <NUM> and a negative active material <NUM> supported by the negative current collector <NUM>. The negative current collector <NUM> is a conductive member having skeletons arranged in substantially the form of a grid or a net, and is formed of, for example, lead or a lead alloy. The negative current collector <NUM> has a negative electrode lug <NUM> protruding upward near the upper end of the negative current collector <NUM>. The negative active material <NUM> contains lead. The negative active material <NUM> may further contain a known additive.

The separator <NUM> is formed of an insulating material (e.g., glass or synthetic resin). The separator <NUM> is disposed so as to be interposed between the positive electrode plate <NUM> and the negative electrode plate <NUM> adjacent to each other. The separator <NUM> may be configured as an integral member or as a set of a plurality of members provided for each combination of the positive electrode plate <NUM> and the negative electrode plate <NUM>.

The positive electrode lug <NUM> of each of the plurality of positive electrode plates <NUM> constituting the electrode group <NUM> is connected to a positive-side strap <NUM> formed of, for example, lead or a lead alloy. That is, the plurality of positive electrode plates <NUM> are electrically connected in parallel through the positive-side straps <NUM>. Similarly, the negative electrode lugs <NUM> of each of the plurality of negative electrode plates <NUM> constituting the electrode group <NUM> is connected to a negative-side strap <NUM> formed of, for example, lead or a lead alloy. That is, the plurality of negative electrode plates <NUM> are electrically connected in parallel through the negative-side straps <NUM>. Hereinafter, the positive-side strap <NUM> and the negative-side strap <NUM> are also collectively referred to as "straps <NUM>, <NUM>.

In a lead-acid battery <NUM>, the negative-side strap <NUM> housed in one cell chamber <NUM> is connected to the positive-side strap <NUM> housed in another cell chamber <NUM> adjacent to one side (e.g., positive X-axis side) of the one cell chamber <NUM> through a connection member <NUM> formed of, for example, lead or a lead alloy. The positive-side strap <NUM> housed in the cell chamber <NUM> is connected to the negative-side strap <NUM> housed in another cell chamber <NUM> adjacent to the other side (e.g., negative X-axis direction side) in the cell chamber <NUM> through a connection member <NUM>. That is, the plurality of electrode groups <NUM> provided in the lead-acid battery <NUM> are electrically connected in series through the straps <NUM>, <NUM> and the connection member <NUM>. As illustrated in <FIG>, the positive-side strap <NUM> housed in the cell chamber <NUM> located at the end on one side in the cell arrangement direction (negative X-axis side) is connected not to the connection member <NUM> but to a positive pole <NUM> to be described later. As illustrated in <FIG>, the negative-side strap <NUM> housed in the cell chamber <NUM> located at the end on the other side in the cell arrangement direction (positive X-axis side) is connected not to the connection member <NUM> but to a negative pole <NUM> to be described later.

The positive-side terminal <NUM> is disposed near the end of the housing <NUM> on one side in the cell arrangement direction (negative X-axis side), and the negative-side terminal <NUM> is disposed near the end of the housing <NUM> on the other side in the cell arrangement direction (positive X-axis side).

As illustrated in <FIG>, the positive-side terminal <NUM> includes a positive-side bushing <NUM> and the positive pole <NUM>. The positive-side bushing <NUM> is a substantially cylindrical conductive member having a vertically penetrating hole formed therein and is formed of, for example, a lead alloy. The lower portion of the positive-side bushing <NUM> is embedded in the lid <NUM> by insert molding, and the upper portion of the positive-side bushing <NUM> protrudes upward from the upper surface of the lid <NUM>. The positive pole <NUM> is a substantially cylindrical conductive member and is formed of, for example, a lead alloy. The positive pole <NUM> has is inserted in a hole of the positive-side bushing <NUM>. The upper end of the positive pole <NUM> is located substantially at the same position as the upper end of the positive-side bushing <NUM> and is joined to the positive-side bushing <NUM> by, for example, welding. The lower end of the positive pole <NUM> protrudes downward of the lower end of the positive-side bushing <NUM> and further protrudes downward of the lower surface of the lid <NUM>. As described above, the lower end of the positive pole <NUM> is connected to the positive-side strap <NUM> housed in the cell chamber <NUM> located at the end on one side in the cell arrangement direction (negative X-axis side).

As illustrated in <FIG>, the negative-side terminal <NUM> includes a negative-side bushing <NUM> and the negative pole <NUM>. The negative-side bushing <NUM> is a substantially cylindrical conductive member having a vertically penetrating hole formed therein and is formed of, for example, a lead alloy. The lower portion of the negative-side bushing <NUM> is embedded in the lid <NUM> by insert molding, and the upper portion of the negative-side bushing <NUM> protrudes upward from the upper surface of the lid <NUM>. The negative pole <NUM> is a substantially cylindrical conductive member and is formed of, for example, a lead alloy. The negative pole <NUM> is inserted in a hole of the negative-side bushing <NUM>. The upper end of the negative pole <NUM> is located substantially at the same position as the upper end of the negative-side bushing <NUM>, and is joined to the negative-side bushing <NUM> by, for example, welding. The lower end of the negative pole <NUM> protrudes downward of the lower end of the negative-side bushing <NUM> and further protrudes downward of the lower surface of the lid <NUM>. As described above, the lower end of the negative pole <NUM> is connected to the negative-side strap <NUM> housed in the cell chamber <NUM> located at the end on the other side in the cell arrangement direction (positive X-axis side).

During the discharge of the lead-acid battery <NUM>, a load (not illustrated) is connected to the positive-side bushing <NUM> of the positive-side terminal <NUM> and the negative-side bushing <NUM> of the negative-side terminal <NUM>. Electric power generated by a reaction (a reaction that generates lead sulfate from lead dioxide) at the positive electrode plate <NUM> of each electrode group <NUM> and a reaction (a reaction that generates lead sulfate from lead) at the negative electrode plate <NUM> of each electrode group <NUM> is supplied to the load. During the charge of the lead-acid battery <NUM>, a power source (not illustrated) is connected to the positive-side bushing <NUM> of the positive-side terminal <NUM> and the negative-side bushing <NUM> of the negative-side terminal <NUM>. By electric power supplied from the power supply, a reaction (a reaction that generates lead dioxide from lead sulfate) at the positive electrode plate <NUM> of each electrode group <NUM> and a reaction (a reaction that generates lead from lead sulfate) at the negative electrode plate <NUM> of each electrode group <NUM>, and the lead-acid battery <NUM> is charged.

As illustrated in <FIG> and <FIG>, the lid <NUM> is a lid body having a so-called double lid structure and includes an inner lid <NUM> and an upper lid <NUM>. The internal space of the lid <NUM> is formed between the inner lid <NUM> and the upper lid <NUM>. <FIG> is an explanatory view illustrating an XY plan view of the inner lid <NUM> as viewed from above (upper lid <NUM> side), and <FIG> is an XY plan view of the upper lid <NUM> as viewed from the lower side (inner lid <NUM>). <FIG> is a perspective view illustrating the internal configuration of the inner lid <NUM> and the upper lid <NUM>. However, for the sake of convenience, <FIG> illustrates a state in which the upper lid <NUM> is separated from the inner lid <NUM>, and only a portion of the inner lid <NUM> and the upper lid <NUM> constituting one compartment <NUM> is illustrated. <FIG> is an explanatory view illustrating the XZ sectional configuration of the lid <NUM> at the position VII-VII in <FIG>. However, <FIG> illustrates an XZ sectional configuration of the upper lid <NUM> when the lid <NUM> illustrated in <FIG> is placed on the inner lid <NUM>.

The internal space of the lid <NUM> is divided by partitions <NUM> into a plurality of (the same number as the number of cell chambers <NUM>) compartments <NUM> arranged in the cell arrangement direction by the partition <NUM>. Each compartment <NUM> corresponds to one of the plurality of cell chambers <NUM> and is located directly above the corresponding cell chamber <NUM>. Hereinafter, a specific description will be given.

Specifically, as illustrated in <FIG> and <FIG>, the inner lid <NUM> has a flat inner-lid body <NUM>, an inner-lid peripheral wall <NUM>, and a plurality (one less than the number of cell chambers <NUM>) of inner-lid partitions <NUM>. The inner-lid peripheral wall <NUM> is disposed in a region of the upper surface of the inner-lid body <NUM> on the side opposite to the terminals <NUM>, <NUM> in a direction (Y-axis direction, hereinafter referred to as "depth direction") substantially orthogonal to the cell arrangement direction (X-axis direction). The inner-lid peripheral wall <NUM> is formed so as to protrude upward from the upper surface of the inner-lid body <NUM>. The inner-lid peripheral wall <NUM> has a substantially rectangular frame shape in a vertical direction (Z-axis view). The plurality of inner-lid partitions <NUM> are arranged in the inner-lid peripheral wall <NUM> at predetermined intervals in the cell arrangement direction. Each of the inner-lid partitions <NUM> extends in the depth direction, and both ends of each of the inner-lid partitions <NUM> in the depth direction are connected to the inner peripheral surface of the inner-lid peripheral wall <NUM> (cf.

Meanwhile, as illustrated in <FIG>, <FIG>, <FIG>, and <FIG>, the upper lid <NUM> has a flat upper-lid body <NUM>, an upper-lid peripheral wall <NUM>, and a plurality (one less than the number of cell chambers <NUM>) of upper-lid partitions <NUM>. The upper-lid peripheral wall <NUM> is formed so as to protrude downward from the lower surface of the upper-lid body <NUM>. A vertical view (Z-axis view) of the upper-lid peripheral wall <NUM> is a substantially rectangular frame shape extending along the peripheral edge portion of the upper-lid body <NUM>. Discharge ports <NUM> penetrating the upper-lid peripheral wall <NUM> are formed at both ends of the upper-lid peripheral wall <NUM> facing each other in the cell arrangement direction (X-axis direction). The plurality of upper-lid partitions <NUM> are arranged at predetermined intervals in the cell arrangement direction. Each upper-lid partition <NUM> extends in the depth direction (Y-axis direction), and both ends of each upper-lid partition <NUM> in the depth direction are connected to the inner peripheral surface of the upper-lid peripheral wall <NUM> (cf. However, in each upper-lid partition <NUM>, a first cutout <NUM> is formed to be opened. Note that no cutout is formed in each of the above-mentioned inner-lid partitions <NUM> formed in the inner lid <NUM>.

The inner-lid peripheral wall <NUM> and the upper-lid peripheral wall <NUM> are joined by thermal welding to form a peripheral wall <NUM> constituting the outer peripheral surface of the lid <NUM>, thereby forming the internal space described above inside the lid <NUM>. Each inner-lid partition <NUM> and each upper-lid partition <NUM> are joined by thermal welding to form the partition <NUM>, whereby the internal space of the lid <NUM> is divided into a plurality of compartments <NUM>. The plurality of compartments <NUM> communicate with each other through the first cutouts <NUM> formed in the respective upper-lid partitions <NUM>.

Each compartment <NUM> includes an electrolyte solution filling chamber <NUM>, a cell communication individual chamber <NUM>, and an exhaust flow passage <NUM>. The compartment <NUM> located at the end in the cell arrangement direction (X-axis direction) (hereinafter referred to as "end-side compartment <NUM>") further includes a concentrated exhaust chamber <NUM> (cf. <FIG>, <FIG>, and <FIG>).

As illustrated in <FIG> and <FIG>, the electrolyte solution filling chamber <NUM> is a space for filling each cell chamber <NUM> of the container <NUM> with the electrolyte solution <NUM>. Specifically, the electrolyte solution filling chamber <NUM> is a space surrounded by an electrolyte solution filling sidewall <NUM> having a substantially cylindrical shape in a vertical view (Z-axis view). As illustrated in <FIG> and <FIG>, an inner-lid electrolyte solution filling sidewall <NUM> is formed in the inner-lid peripheral wall <NUM> on the upper surface of the inner-lid body <NUM> so as to protrude upward from the inner-lid body <NUM>. The inner-lid electrolyte solution filling sidewall <NUM> has a substantially cylindrical shape in the vertical view. The electrolyte solution filling hole <NUM> vertically penetrating the inner-lid body <NUM> is formed in the inner-lid electrolyte solution filling sidewall <NUM> on the upper surface of the inner-lid body <NUM>. The electrolyte solution <NUM> can be poured into the cell chamber <NUM> of the container <NUM> from the electrolyte solution filling hole <NUM>. Meanwhile, as illustrated in <FIG> and <FIG>, in the upper-lid peripheral wall <NUM> on the lower surface of the upper-lid body <NUM>, an upper-lid electrolyte solution filling sidewall <NUM> is formed at a position facing the inner-lid electrolyte solution filling sidewall <NUM> so as to protrude downward from the upper-lid body <NUM>. The upper-lid electrolyte solution filling sidewall <NUM> has a substantially cylindrical shape in the vertical view. The inner-lid electrolyte solution filling sidewall <NUM> and the upper-lid electrolyte solution filling sidewall <NUM> are joined by thermal welding to form the electrolyte solution filling sidewall <NUM>, thereby forming the electrolyte solution filling chamber <NUM> inside the lid <NUM> (cf. <FIG> and <FIG>).

The cell communication individual chamber <NUM> is a space in which communication holes (an exhaust hole <NUM> and a reflux hole <NUM> to be described later) are formed and which communicates with the cell chamber <NUM> through the communication hole. Specifically, the cell communication individual chamber <NUM> is a space surrounded by the partition <NUM> and an exhaust sidewall <NUM>, and the cell communication individual chamber <NUM> has a substantially trapezoidal shape in the vertical view. As illustrated in <FIG> and <FIG>, in the inner-lid peripheral wall <NUM> on the upper surface of the inner-lid body <NUM>, an inner-lid exhaust sidewall <NUM> constituting a substantially trapezoidal partition together with the inner-lid partition <NUM> is formed so as to protrude upward from the inner-lid body <NUM>. Meanwhile, as illustrated in <FIG> and <FIG>, in the upper-lid peripheral wall <NUM> on the lower surface of the upper-lid body <NUM>, an upper-lid exhaust sidewall <NUM> constituting a substantially trapezoidal partition together with the upper-lid partition <NUM> is formed at a position facing the inner-lid exhaust sidewall <NUM> so as to protrude downward from the upper-lid body <NUM>. The inner-lid exhaust sidewall <NUM> and the upper-lid exhaust sidewall <NUM> are joined by thermal welding to form an exhaust sidewall <NUM>, thereby forming the cell communication individual chamber <NUM> inside the lid <NUM> (cf. <FIG>, <FIG>, and <FIG>). However, as illustrated in <FIG>, a second cutout <NUM> is formed between the inner-lid partition <NUM> and the inner-lid exhaust sidewall <NUM>, and no cutout is formed between the upper-lid partition <NUM> and the upper-lid exhaust sidewall <NUM>. Hence the cell communication individual chamber <NUM> communicates with the exhaust flow passage <NUM> through the second cutout <NUM>. The cell communication individual chamber <NUM> corresponds to the communication chamber in the claims, the partition <NUM> and the exhaust sidewall <NUM> correspond to the sidewall in the claims, and the second cutout <NUM> corresponds to the vent hole in the claims.

A portion of the inner-lid body <NUM> located inside the inner-lid partition <NUM> and the inner-lid exhaust sidewall <NUM> in a vertical direction view includes a first partition wall <NUM>, a second partition wall <NUM>, and a step <NUM> for connecting the first partition wall <NUM> and the second partition wall <NUM>. The first partition wall <NUM>, the second partition wall <NUM>, and the step <NUM> are walls for partition walling the cell chamber <NUM> and the cell communication individual chamber <NUM>. The first partition wall <NUM> is disposed at a position closer to the second cutout <NUM> than the second partition wall <NUM>. As illustrated in <FIG>, the first partition wall <NUM> and the second cutout <NUM> are separated from each other in the vertical direction (Z-axis direction). In other words, the second cutout <NUM> is located above the upper surface of the first partition wall <NUM>. Specifically, a stepped part <NUM> extending upward from the first partition wall <NUM> is formed between the first partition wall <NUM> and the second cutout <NUM>, whereby the first partition wall <NUM> and the second cutout <NUM> are separated from each other in the vertical direction. The second cutout <NUM> and the lower surface of the upper-lid body <NUM> are also separated from each other in the vertical direction. In other words, the second cutout <NUM> is located below the lower surface of the upper-lid body <NUM>.

In the first partition wall <NUM>, an exhaust hole <NUM> is formed penetrating the first partition wall <NUM> in the vertical direction. On the upper surface of the first partition wall <NUM>, a substantially tubular communication tubular part <NUM> is formed extending upward from the first partition wall <NUM> while surrounding the exhaust hole <NUM>. An upper tip 332A of the communication tubular part <NUM> is located above the upper surface of the inner-lid partition <NUM> and the upper surface of the inner-lid exhaust sidewall <NUM>, and reaches the inside of the upper lid <NUM> (cf.

As described above, the second partition wall <NUM> is disposed at a position farther from the second cutout <NUM> than the first partition wall <NUM>. The second partition wall <NUM> is located below the first partition wall <NUM> (electrode group <NUM> side) through the step <NUM> extending in the vertical direction. In the second partition wall <NUM>, a reflux hole <NUM> is formed penetrating the second partition wall <NUM> in the vertical direction. That is, the reflux hole <NUM> is disposed at a position closer to the liquid surface of the electrolyte solution <NUM> than the exhaust hole <NUM>. Note that the first partition wall <NUM> is inclined obliquely downward toward the second partition wall <NUM>, and the second partition wall <NUM> is inclined toward the reflux hole <NUM> (cf. Thereby, when the lead-acid battery <NUM> is set to the normal position, the electrolyte solution <NUM> remaining in the cell communication individual chamber <NUM> can be smoothly guided to the reflux hole <NUM> along the inclination of the first partition wall <NUM> and the second partition wall <NUM> and returned to the inside of the cell chamber <NUM>. The exhaust hole <NUM> and the reflux hole <NUM> correspond to the communication hole in the claims. The portion of the upper-lid body <NUM> facing the first partition wall <NUM> and the second partition wall <NUM> corresponds to the facing wall in the claims.

As illustrated in <FIG> and <FIG>, on the lower surface of the upper-lid body <NUM>, an exhaust tubular wall <NUM> is formed at a position facing an exhaust hole <NUM> formed in the first partition wall <NUM> of the inner-lid body <NUM> so as to protrude downward from the upper-lid body <NUM>. The exhaust tubular wall <NUM> has a substantially square tubular shape in the vertical direction (Z-axis view). A lower tip 432A of the exhaust tubular wall <NUM> is located below the second cutout <NUM>. The tip 432A of the exhaust tubular wall <NUM> is located below the upper tip 332A of the communication tubular part <NUM> of the inner lid <NUM>, and the exhaust tubular wall <NUM> is disposed so as to surround the communication tubular part <NUM> of the inner lid <NUM>. The exhaust tubular wall <NUM> corresponds to the inner wall in the claims, and the tip 432A of the exhaust tubular wall <NUM> corresponds to the tip of the inner wall on the other side in the first direction in the claims.

<FIG> is an XY plan view illustrating the configuration of the upper surface side of the inner lid <NUM>. In <FIG>, the exhaust tubular wall <NUM> formed in the upper lid <NUM> is illustrated by a two-dot chain line. As illustrated in <FIG>, a part of the exhaust tubular wall <NUM> faces a second cutout <NUM> (vent hole) formed in the cell communication individual chamber <NUM>. A first distance L1, which is the shortest distance between the exhaust tubular wall <NUM> and a hole formation part (a cutout between upper-lid partition <NUM> and upper-lid exhaust sidewall <NUM>) where the second cutout <NUM> is formed, is shorter than a second distance L2, which is the shortest distance between the exhaust tubular wall <NUM> and a portion (communication tubular part <NUM>) where the exhaust hole <NUM> is formed (cf. Note that the first distance L1 is preferably <NUM> or less, and more preferably <NUM> or less. In the present embodiment, the first distance L1 is <NUM>. The tip 432A of the exhaust tubular wall <NUM> is located below the entire second cutout <NUM> (cell chamber <NUM> side). The width of the second cutout <NUM> in at least one direction (e.g., the lateral width in a direction perpendicular to the vertical direction) is preferably <NUM> or less, and more preferably <NUM> or less. In the present embodiment, the lateral width of the second cutout <NUM> is <NUM>.

<FIG> is a perspective view illustrating the configuration of the lower surface side of the upper lid <NUM>. As illustrated in <FIG> and <FIG>, an internal flow passage Q communicating with the second cutout <NUM> and located closer to the cell chamber <NUM> side than the second cutout <NUM> is formed between the exhaust tubular wall <NUM> and the exhaust sidewall <NUM> (the upper-lid partition <NUM> and the upper-lid exhaust sidewall <NUM>). The facing distance between the facing surfaces of the exhaust tubular wall <NUM> and the exhaust sidewall <NUM> facing each other and forming the internal flow passage Q is preferably <NUM> or less, and more preferably <NUM> or less. In the present embodiment, the facing distance is <NUM>.

As illustrated in <FIG> and <FIG>, at least a portion of the surfaces of the facing surfaces of the exhaust tubular wall <NUM> and the exhaust sidewall <NUM> has an uneven part T. Specifically, of the four outer surfaces of the exhaust tubular wall <NUM>, the outer surface on the reflux hole <NUM> side is a substantially flat surface, and a plurality of uneven parts T are formed on the remaining three outer surfaces. A plurality of uneven parts T are formed in portions of the inner peripheral surfaces of the inner-lid partition <NUM> and the inner-lid exhaust sidewall <NUM> constituting the exhaust sidewall <NUM>, the portions facing the remaining three outer surfaces of the exhaust tubular wall <NUM>. Note that the remaining three outer surfaces of the exhaust tubular wall <NUM> and the exhaust sidewall <NUM> (the inner-lid partition <NUM> and the inner-lid exhaust sidewall <NUM>) face each other with a distance substantially equal to the lateral width of the second cutout <NUM>, thereby forming the internal flow passage Q. More specifically, on the facing surfaces of the exhaust tubular wall <NUM> and the exhaust sidewall <NUM>, a plurality of uneven parts T extending in the vertical direction (Z-axis direction) are arranged in a direction parallel to the facing surface and substantially orthogonal to the vertical direction. The difference in height between the valley and peak of the uneven part T is preferably <NUM> or more. On the surface of the partition wall (the first partition wall <NUM> and the second partition wall <NUM>) where the second cutout <NUM> is formed on the side of the upper lid <NUM>, no uneven part T is formed, and the partition wall has a substantially flat surface.

As illustrated in <FIG> and <FIG>, in each end-side compartment <NUM>, the concentrated exhaust chamber <NUM> is located between the electrolyte solution filling chamber <NUM> and the cell communication individual chamber <NUM>. The concentrated exhaust chamber <NUM> is a space surrounded by the concentrated exhaust sidewall <NUM> and has a substantially circular shape in the vertical view. Specifically, as illustrated in <FIG> and <FIG>, a substantially arcuate inner-lid concentrated exhaust sidewall <NUM> having a third cutout <NUM> formed on the side of the inner-lid electrolyte solution filling sidewall <NUM> is formed on the upper surface of the inner-lid body <NUM> so as to protrude upward from the inner-lid body <NUM>. Meanwhile, as illustrated in <FIG> and <FIG>, a substantially cylindrical upper-lid concentrated exhaust sidewall <NUM> is formed on the lower surface of the upper-lid body <NUM> at a position facing the inner-lid concentrated exhaust sidewall <NUM> so as to protrude downward from the upper-lid body <NUM>. A duct <NUM> communicating with the discharge port <NUM> is formed in the upper-lid concentrated exhaust sidewall <NUM>. The inner-lid concentrated exhaust sidewall <NUM> and the upper-lid concentrated exhaust sidewall <NUM> are joined by thermal welding to form a concentrated exhaust sidewall <NUM>, thereby forming the concentrated exhaust chamber <NUM> inside the lid <NUM> (cf. <FIG> and <FIG>). Further, a filter, not illustrated, is disposed in the concentrated exhaust chamber <NUM>, and a gas G, having entered the inner-lid concentrated exhaust sidewall <NUM> from the exhaust flow passage <NUM> through the third cutout <NUM>, enters the upper-lid concentrated exhaust sidewall <NUM> side through the filter, and is discharged to the outside of the lead-acid battery <NUM> (Lid <NUM>) through the discharge port <NUM>.

As illustrated in <FIG>, the exhaust flow passage <NUM> communicates with the cell communication individual chamber <NUM> through the second cutout <NUM> and also communicates with the discharge port <NUM>. Specifically, in the end-side compartment <NUM>, the exhaust flow passage <NUM> communicates directly with the concentrated exhaust chamber <NUM>, and further communicates with the discharge port <NUM> through the concentrated exhaust chamber <NUM>. In the end-side compartment <NUM>, the exhaust flow passage <NUM> extends from the second cutout <NUM> along the outer periphery of the exhaust sidewall <NUM>, passes between the cell communication individual chamber <NUM> and the concentrated exhaust chamber <NUM>, further extends along the outer periphery of the electrolyte solution filling chamber <NUM>, and reaches the third cutout <NUM> of the concentrated exhaust chamber <NUM>.

More specifically, as illustrated in <FIG> and <FIG>, on the upper surface of the inner-lid body <NUM>, a coupling wall <NUM> for coupling the inner-lid electrolyte solution filling sidewall <NUM> and the inner-lid concentrated exhaust sidewall <NUM> is formed so as to protrude upward from the inner-lid body <NUM>. Thus, an inner-lid exhaust flow passage <NUM>, surrounded by an inner-lid peripheral wall <NUM>, an inner-lid exhaust sidewall <NUM>, the inner-lid partition <NUM>, the inner-lid electrolyte solution filling sidewall <NUM>, and the coupling wall <NUM>, is formed in the inner lid <NUM>. The bottom surface in the inner-lid exhaust flow passage <NUM> in the inner-lid body <NUM> is flush over the entire length of the inner-lid exhaust flow passage <NUM> and is inclined toward the second cutout <NUM>. Thereby, when the lead-acid battery <NUM> is in the normal position, the electrolyte solution <NUM> having leaked into the exhaust flow passage <NUM> can be smoothly returned into the cell communication individual chamber <NUM> through the bottom surface in the inner-lid exhaust flow passage <NUM>. That is, the inner-lid exhaust flow passage <NUM> is continuously connected over the entire length. Note that a plurality of ribs <NUM> are formed in the inner-lid exhaust flow passage <NUM>. The plurality of ribs <NUM> trap mist (steam) contained in the gas G from the second cutout <NUM> to the third cutout <NUM>, and aggregate the mist into water. The plurality of ribs <NUM> prevent the electrolyte solution <NUM>, having flowed out of the cell communication individual chamber <NUM> to the exhaust flow passage <NUM> through the second cutout <NUM>, from flowing to the discharge port <NUM> side.

Meanwhile, as illustrated in <FIG> and <FIG>, a first coupling wall <NUM> coupling the upper-lid partition <NUM> and the upper-lid concentrated exhaust sidewall <NUM>, a second coupling wall <NUM> coupling the upper-lid partition <NUM> and the upper-lid electrolyte solution filling sidewall <NUM>, and a third coupling wall <NUM> coupling the upper-lid electrolyte solution filling sidewall <NUM> and the upper-lid concentrated exhaust sidewall <NUM> are formed on the lower surface of the upper-lid body <NUM> so as to each protrude downward from the upper-lid body <NUM>. No cutout is formed in any of the first coupling wall <NUM>, the second coupling wall <NUM> and the third coupling wall <NUM>. Accordingly, a first upper-lid space <NUM>, a second upper-lid space <NUM>, and a third upper-lid space <NUM> are formed in the end-side compartment <NUM> of the upper lid <NUM>. The first upper-lid space <NUM> is a space surrounded by the upper-lid peripheral wall <NUM>, the upper-lid exhaust sidewall <NUM>, the upper-lid concentrated exhaust sidewall <NUM>, and the coupling wall <NUM>, and is disposed at a position closest to the second cutout <NUM>. The second upper-lid space <NUM> is a space surrounded by the upper-lid partition <NUM>, the first coupling wall <NUM>, the second coupling wall <NUM>, and the third coupling wall <NUM>, and is disposed at a position farther from the second cutout <NUM> than the first upper-lid space <NUM>. The third upper-lid space <NUM> is a space surrounded by the upper-lid peripheral wall <NUM>, the upper-lid partition <NUM>, the upper-lid electrolyte solution filling sidewall <NUM>, the second coupling wall <NUM>, and the third coupling wall <NUM>, and is disposed at a position still farther from the second cutout <NUM> than the second upper-lid space <NUM>. As described above, in the end-side compartment <NUM>, the exhaust flow passage <NUM> is continuously connected on the inner lid <NUM> side, and is divided into three spaces <NUM>, <NUM>, <NUM> on the upper lid <NUM> side by the first coupling wall <NUM>, the second coupling wall <NUM>, and the third coupling wall <NUM>. The total volume (the volume of the electrolyte solution <NUM> contained) of the second upper-lid space <NUM> and the third upper-lid space <NUM> is larger than the volume of the upper-lid exhaust sidewall <NUM>. The volume of the first upper-lid space <NUM> is larger than that of the second upper-lid space <NUM>.

In the compartment <NUM> (hereinafter referred to as "inner compartment <NUM>") located inside the end-side compartment <NUM> in the cell arrangement direction (X-axis direction) among the plurality of compartments <NUM>, the exhaust flow passage <NUM> communicates with the concentrated exhaust chamber <NUM> through the other compartment <NUM>. In the inner compartment <NUM>, the exhaust flow passage <NUM> extends from the second cutout <NUM> along the outer periphery of the exhaust sidewall <NUM>, passes between the cell communication individual chamber <NUM> and the concentrated exhaust chamber <NUM>, and reaches the first cutout <NUM> formed in the upper-lid partition <NUM>.

More specifically, as illustrated in <FIG>, an inner-lid exhaust flow passage <NUM>, surrounded by the inner-lid peripheral wall <NUM>, the inner-lid exhaust sidewall <NUM>, the inner-lid partition <NUM>, and the inner-lid electrolyte solution filling sidewall <NUM>, is formed in the inner lid <NUM>. The bottom surface in the inner-lid exhaust flow passage <NUM> in the inner-lid body <NUM> is flush over the entire length of the inner-lid exhaust flow passage <NUM> and is inclined toward the second cutout <NUM>. That is, the inner-lid exhaust flow passage <NUM> is continuously connected over the entire length. Thereby, when the lead-acid battery <NUM> is in the normal position, the electrolyte solution <NUM> having leaked into the exhaust flow passage <NUM> can be smoothly returned into the cell communication individual chamber <NUM> through the bottom surface in the inner-lid exhaust flow passage <NUM>. Note that a plurality of ribs <NUM> are formed in the inner-lid exhaust flow passage <NUM>. The plurality of ribs <NUM> trap mist (steam) contained in the gas G from the second cutout <NUM> to the third cutout <NUM>, and aggregate the mist into water. The plurality of ribs <NUM> prevent the electrolyte solution <NUM>, having flowed out of the cell communication individual chamber <NUM> to the exhaust flow passage <NUM> through the second cutout <NUM>, from flowing to the first cutout <NUM> side.

Meanwhile, as illustrated in <FIG>, a fourth coupling wall <NUM> coupling the upper-lid partitions <NUM> facing each other and a pair of fifth coupling walls <NUM> coupling the upper-lid electrolyte solution filling sidewalls <NUM> and the upper-lid partitions <NUM> are formed on the lower surface of the upper-lid body <NUM> so as to each protrude downward from the upper-lid body <NUM>. No cutout is formed in either the fourth coupling wall <NUM> or the fifth coupling wall <NUM>. Accordingly, a fourth upper-lid space <NUM>, a fifth upper-lid space <NUM>, and a sixth upper-lid space <NUM> are formed in the inner compartment <NUM> of the upper lid <NUM>. The fourth upper-lid space <NUM> is a space surrounded by the upper-lid peripheral wall <NUM>, the upper-lid partition <NUM>, the upper-lid exhaust sidewall <NUM>, and the fourth coupling wall <NUM>, and is disposed at a position closest to the second cutout <NUM>. The fifth upper-lid space <NUM> is a space surrounded by the upper-lid partition <NUM>, the fourth coupling wall <NUM>, the upper-lid electrolyte solution filling sidewall <NUM>, and the fifth coupling wall <NUM>, and is disposed at a position farther from the second cutout <NUM> than the fourth upper-lid space <NUM>. The sixth upper-lid space <NUM> is a space surrounded by the upper-lid peripheral wall <NUM>, the upper-lid partition <NUM>, the upper-lid electrolyte solution filling sidewall <NUM>, and the fifth coupling wall <NUM>, and is disposed at a position still farther from the second cutout <NUM> than the fifth upper-lid space <NUM>. As described above, in the inner compartment <NUM>, the exhaust flow passage <NUM> is continuously connected to each other on the inner lid <NUM> side, and is divided into three spaces <NUM>, <NUM>, <NUM> on the upper lid <NUM> side by the fourth coupling wall <NUM> and the fifth coupling walls <NUM>.

When the lead-acid battery <NUM> is inverted in position, the electrolyte solution <NUM> in the cell chamber <NUM> flows into the cell communication individual chamber <NUM> through the communication holes (the exhaust holes <NUM> and the reflux hole <NUM>) formed in the cell communication individual chamber <NUM>, and the water level of the electrolyte solution <NUM> in the cell communication individual chamber <NUM> rises. When the water level of the electrolyte solution <NUM> reaches the second cutout <NUM> formed in the cell communication individual chamber <NUM>, the electrolyte solution <NUM> may flow out to the outside the cell communication individual chamber <NUM> (to the exhaust flow passage <NUM>) through the second cutout <NUM>.

Here, supposing that the tip 432A of the exhaust tubular wall <NUM> is disposed on the upper-lid body <NUM> side (positive Z-axis) from at least a part of the second cutout <NUM>, or the distance between the exhaust tubular wall <NUM> and the second cutout <NUM> is longer than the distance between the exhaust tubular wall <NUM> and the exhaust hole <NUM> or the reflux hole <NUM>, the electrolyte solution <NUM> would easily flow out to the outside of the cell communication individual chamber <NUM>. That is, in these configurations, there is no obstacle preventing the air existing in the exhaust flow passage <NUM> from flowing into the cell communication individual chamber <NUM> through the second cutout <NUM>. Therefore, the air existing in the exhaust flow passage <NUM> easily enters the cell communication individual chamber <NUM> through the second cutout <NUM>. As a result, by so-called vapor-liquid exchange in which the electrolyte solution <NUM> flows out of the cell communication individual chamber <NUM> into the exhaust flow passage <NUM> at the same time when air flows from the exhaust flow passage <NUM> into the cell communication individual chamber <NUM>, the electrolyte solution <NUM> easily flows out to the exhaust flow passage <NUM>.

In contrast, in the lead-acid battery <NUM> of the present embodiment, the cell communication individual chamber <NUM> is provided with the exhaust tubular wall <NUM> disposed so as to face the second cutout <NUM> at a position close to the second cutout <NUM>. The tip 432A of the exhaust tubular wall <NUM> on the cell chamber <NUM> side (negative Z-axis) is formed at a position on the cell chamber <NUM> side from the second cutout <NUM>. Therefore, the air existing in the exhaust flow passage <NUM> hardly enters the cell communication individual chamber <NUM> through the second cutout <NUM>, thus preventing the vapor-liquid exchange between the inside and outside of the cell communication individual chamber <NUM>. Thus, according to the present embodiment, it is possible to prevent the electrolyte solution <NUM> from flowing out to the exhaust flow passage <NUM> and further to the outside of the housing <NUM> when the lead-acid battery <NUM> is in the inverted position. Next, the effects of the present embodiment will be described in more detail.

<FIG> is an explanatory view illustrating a change in the water level of the electrolyte solution <NUM> in the cell communication individual chamber <NUM> when the lead-acid battery <NUM> is in the inverted position. The XZ sectional configuration of the lid <NUM> illustrated in <FIG> is obtained by vertically reversing the XZ sectional configuration of the lid <NUM> illustrated in <FIG>. As illustrated in <FIG>, when the lead-acid battery <NUM> is inverted in position, the electrolyte solution <NUM> in the cell chamber <NUM> first flows into the exhaust tubular wall <NUM> through the exhaust hole <NUM>. Thereafter, when the space surrounded by the exhaust tubular wall <NUM> is filled with the electrolyte solution <NUM> (cf. <FIG>), the electrolyte solution <NUM> in the exhaust tubular wall <NUM> overflows to the outside of the exhaust tubular wall <NUM> in the cell communication individual chamber <NUM> (the outside of the exhaust tubular wall <NUM> in the upper-lid body <NUM>). Thereafter, when the water level of the electrolyte solution <NUM> outside the exhaust tubular wall <NUM> in the cell communication individual chamber <NUM> reaches the lower end of the second cutout <NUM>, the electrolyte solution <NUM> starts to flow out of the cell communication individual chamber <NUM> to the exhaust flow passage <NUM> through the second cutout <NUM>. Thereafter, when the water level of the electrolyte solution <NUM> outside the exhaust tubular wall <NUM> in the cell communication individual chamber <NUM> becomes equal to the water level of the electrolyte solution in the exhaust tubular wall <NUM> (cf. <FIG>), the water level of the electrolyte solution <NUM> does not rise unless both inside and outside the exhaust tubular wall <NUM> are filled with the electrolyte solution <NUM>, so that the rising speed of the water level of the electrolyte solution <NUM> in the cell communication individual chamber <NUM> decreases.

Here, supposing that the tip 432A of the exhaust tubular wall <NUM> is formed on the upper-lid body <NUM> side (the lower side (positive Z-axis) in <FIG>) from at least one portion of the second cutout <NUM>, a large amount of electrolyte solution <NUM> would flow out of the cell communication individual chamber <NUM> into the exhaust flow passage <NUM>. That is, in such a configuration, a continuous space continuously continuing from the second cutout <NUM> to the reflux hole <NUM> in the cell communication individual chamber <NUM> exists for a relatively long time in the slow water level period when the rising speed of the water level of the electrolyte solution <NUM> is low. Through the continuous space, the vapor-liquid exchange between the inside and outside of the cell communication individual chamber <NUM> is promoted, and a large amount of the electrolyte solution <NUM> flows out of the cell communication individual chamber <NUM> to the exhaust flow passage <NUM>.

In contrast, in the lead-acid battery <NUM> of the present embodiment, the tip 432A of the exhaust tubular wall <NUM> is formed at a position on the cell chamber <NUM> side (the upper side (negative Z-axis) in <FIG>) from the second cutout <NUM>. Therefore, when the water levels of the electrolyte solution <NUM> inside and outside the exhaust tubular wall <NUM> become the same, the second cutout <NUM> has already been brought into a closed state by the electrolyte solution <NUM>, and the continuous space does not exist, so that the air existing in the exhaust flow passage <NUM> hardly enters the cell communication individual chamber <NUM> through the second cutout <NUM>. Hence the vapor-liquid exchange hardly occurs inside and outside the cell communication individual chamber <NUM> during the slow water level period, and thereby preventing the outflow of the electrolyte solution <NUM> from the cell communication individual chamber <NUM> to the exhaust flow passage <NUM>. That is, according to the lead-acid battery <NUM> of the present embodiment, the outflow of the electrolyte solution <NUM> from the cell communication individual chamber <NUM> to the exhaust flow passage <NUM> can be more effectively prevented in the inverted position of the lead-acid battery <NUM>.

In the configuration where the exhaust hole <NUM> and the reflux hole <NUM> which is located closer to the cell chamber <NUM> (negative Z-axis) than the exhaust hole <NUM> are formed in the cell communication individual chamber <NUM> as in the lead-acid battery <NUM> of the present embodiment, when the lead-acid battery <NUM> is inverted in position, the water level of the electrolyte solution <NUM> in the cell communication individual chamber <NUM> reaches the exhaust hole <NUM> earlier than the reflux hole <NUM>. As a result, the exhaust hole <NUM> is closed by the electrolyte solution <NUM>, and the reflux hole <NUM> is opened. Here, supposing that the second cutout <NUM> is formed at a position closer to the reflux hole <NUM> than the exhaust hole <NUM>, a large amount of the electrolyte solution <NUM> would flow out of the cell communication individual chamber <NUM> to the exhaust flow passage <NUM>. That is, even when the water level of the electrolyte solution <NUM> in the cell communication individual chamber <NUM> reaches the exhaust hole <NUM>, a continuous space continuously continuing from the second cutout <NUM> to the reflux hole <NUM> exits in the cell communication individual chamber <NUM>. Through the continuous space, the vapor-liquid exchange between the inside and outside of the cell communication individual chamber <NUM> is promoted, and a large amount of the electrolyte solution <NUM> flows out of the cell communication individual chamber <NUM> to the exhaust flow passage <NUM>.

In contrast, in the lead-acid battery <NUM> of the present embodiment, the second cutout <NUM> is formed at a position closer to the exhaust hole <NUM> than the reflux hole <NUM>. Therefore, when the lead-acid battery <NUM> is inverted in position and the water level of the electrolyte solution <NUM> in the cell communication individual chamber <NUM> reaches the exhaust hole <NUM>, the electrolyte solution <NUM> stored in the cell communication individual chamber <NUM> exists between the second cutout <NUM> and the reflux hole <NUM> in the cell communication individual chamber <NUM>. That is, the continuous space continuously continuing from the second cutout <NUM> to the reflux hole <NUM> is not formed in the cell communication individual chamber <NUM>. This prevents the vapor-liquid exchange between the inside and outside of the cell communication individual chamber <NUM>. Thus, according to the lead-acid battery <NUM> of the present embodiment, the outflow of the electrolyte solution <NUM> from the cell communication individual chamber <NUM> to the exhaust flow passage <NUM> can be more effectively prevented in the inverted position of the lead-acid battery <NUM>.

In the lead-acid battery <NUM> of the present embodiment, at least a portion of the surfaces of the facing surfaces of the exhaust tubular wall <NUM> and the exhaust sidewall <NUM>, which form the internal flow passage Q communicating with the second cutout <NUM> and located closer to the cell chamber <NUM> (negative Z-axis) than the second cutout <NUM>, have the uneven part T. Thereby, as illustrated in <FIG>, at the time when the lead-acid battery <NUM> is inverted in position, and when the electrolyte solution <NUM> in the cell chamber <NUM> flows into the cell communication individual chamber <NUM>, and the second cutout <NUM> is brought into a closed state by the electrolyte solution <NUM>, the air having entered the cell communication individual chamber <NUM> from the exhaust flow passage <NUM> is prevented from moving to the reflux hole <NUM> by the uneven part T. Hence the vapor-liquid exchange between the inside and outside of the cell communication individual chamber <NUM> hardly occurs, and the electrolyte solution <NUM> can be prevented from flowing out of the cell communication individual chamber <NUM> to the exhaust flow passage <NUM>.

In the lead-acid battery <NUM> of the present embodiment, the surface of the partition wall (the first partition wall <NUM> and the second partition wall <NUM>) in which the second cutout <NUM> is formed on the upper-lid body <NUM> side is substantially flat, and the surface of the flow passage wall (at least a portion of the facing surfaces of the exhaust tubular wall <NUM> and the exhaust sidewall <NUM> facing each other) has the uneven part T. Thus, as compared to a case where the uneven part is formed on the partition wall, when the lead-acid battery <NUM> is returned from the inverted position to the normal position, the electrolyte solution <NUM> in the cell communication individual chamber <NUM> can be smoothly guided to the reflux hole <NUM> through the partition wall and returned to the cell chamber <NUM>.

In the lead-acid battery <NUM> of the present embodiment, a plurality of coupling walls (<NUM>, <NUM>, <NUM>, <NUM>) are formed in a portion of the upper-lid body <NUM> constituting the exhaust flow passage <NUM>. Each of the coupling wall fences protrudes from the upper-lid body <NUM> toward the cell chamber <NUM> and continuously extends over the entire width of the exhaust flow passage <NUM> in a direction intersecting the exhaust flow passage <NUM>. Thus, for example, even when the lead-acid battery <NUM> is inverted in position and the electrolyte solution <NUM> in the cell chamber <NUM> flows into the exhaust flow passage <NUM> through the cell communication individual chamber <NUM>, the electrolyte solution <NUM> is first retained between the cell communication individual chamber <NUM> and each coupling fence. Thereafter, the electrolyte solution <NUM> flows into the discharge port <NUM> side from each coupling fence only when the electrolyte solution <NUM> flows out beyond each coupling fence. That is, according to the lead-acid battery <NUM> of the present embodiment, it is possible to prevent the electrolyte solution <NUM> from flowing into the discharge port <NUM> side of the lid <NUM>, as compared to a configuration in which the coupling fence is not formed in the exhaust flow passage <NUM>.

Moreover, the total volume of the second upper-lid space <NUM> and the third upper-lid space <NUM> is larger than the volume of the upper-lid exhaust sidewall <NUM>. Thus, the electrolyte solution <NUM> having flowed into the exhaust flow passage <NUM> from the cell communication individual chamber <NUM> hardly reaches the third upper-lid space <NUM> closest to the discharge port <NUM> formed in the lid <NUM>, so that the electrolyte solution <NUM> can be prevented from leaking out of the lead-acid battery <NUM> through the discharge port <NUM>.

In the lead-acid battery <NUM> of the present embodiment, the volume of the first upper-lid space <NUM> is larger than the volume of the second upper-lid space <NUM>. Thus, as compared to a constitution in which the volume of the first upper-lid space <NUM> is smaller than the volume of the second upper-lid space <NUM>, the electrolyte solution <NUM> having flowed out of the cell communication individual chamber <NUM> hardly goes over the compartment fence closest to the cell communication individual chamber <NUM> and can thus be prevented from approaching the discharge port side of the lid.

The techniques disclosed in the present specification are not limited to the embodiment described above but may be modified in various forms without departing from the scope of the invention, such as the following:.

In the above embodiment, the exhaust tubular wall <NUM> formed so as to protrude from the facing wall constituting the cell communication individual chamber <NUM> (upper-lid body <NUM>) has been exemplified as the inner wall, but the inner wall may be a wall separated from the facing wall or a wall of a shape other than a cylinder such as a flat plate, provided that the inner wall faces the second cutout <NUM>.

In the above embodiment, the lid <NUM> may not include the communication tubular part <NUM>. Further, in the above embodiment, the lid <NUM> may have a configuration in which the second cutout <NUM> is formed at a position closer to the reflux hole <NUM> than the exhaust hole <NUM>. Moreover, in the above embodiment, the reflux hole <NUM> may not be formed in the cell communication individual chamber <NUM>.

In the above embodiment, the bottom surface in the inner-lid exhaust flow passage <NUM> in the inner-lid body <NUM> may have a partition wall that is flush over the entire length of the inner-lid exhaust flow passage <NUM> or may not be inclined toward the second cutout <NUM>.

In the above embodiment, the uneven part T may be formed on each surface of the exhaust tubular wall <NUM> and the exhaust sidewall <NUM> facing each other, or the uneven part T may be formed on only one surface. The uneven part T may be formed also on the upper surface of the inner-lid body <NUM>. The uneven part T may be formed only on one or two outer surfaces of the remaining three outer surfaces of the exhaust tubular wall <NUM>. The uneven parts T may not be formed on the facing surfaces of the exhaust tubular wall <NUM> and the exhaust sidewall <NUM>. Further, the uneven part T is not limited to the one extending in the predetermined direction but may be formed by, for example, hemispherical or columnar convex parts. In addition, as another configuration in which, when the lead-acid battery <NUM> is inverted in position and the second cutout <NUM> is brought into a closed state by the electrolyte solution <NUM>, the air having entered the cell communication individual chamber <NUM> from the exhaust flow passage <NUM> is prevented from moving to the reflux hole <NUM>, the surface roughness of at least a portion of the facing surfaces of the exhaust tubular wall <NUM> and the exhaust sidewall <NUM> may be made larger than the surface roughness of the lower surface of the upper-lid body <NUM>.

Claim 1:
A lead-acid battery (<NUM>) comprising:
a container (<NUM>) having an opening on one side in a first direction corresponding to up direction and formed with a housing chamber (<NUM>) communicating with the opening;
a positive electrode (<NUM>) and a negative electrode (<NUM>) housed in the housing chamber (<NUM>) of the container (<NUM>); and
a lid (<NUM>) disposed so as to close the opening of the container (<NUM>) and has a discharge port (<NUM>) formed on an outer surface of the lid (<NUM>), wherein
a communication chamber (<NUM>) is formed inside the lid (<NUM>), the communication chamber (<NUM>) being surrounded by a partition wall (<NUM>, <NUM>) between the housing chamber (<NUM>) and the communication chamber (<NUM>), a facing wall (<NUM>) that faces the partition wall (<NUM>, <NUM>) in the first direction, and a sidewall that connects the partition wall (<NUM>, <NUM>) and the facing wall (<NUM>),
a communication hole communicating with the housing chamber (<NUM>) is formed in the partition wall (<NUM>, <NUM>) and including an exhaust hole (<NUM>),
a vent hole (<NUM>) communicating with the discharge port (<NUM>) of the lid (<NUM>) is formed in the sidewall,
the communication chamber (<NUM>) is provided with an inner wall (<NUM>) disposed so as to face the exhaust hole(<NUM>),
a first distance (L1) between the inner wall (<NUM>) and the vent hole (<NUM>) in the sidewall is shorter than a second distance (L2) between the inner wall (<NUM>) and the exhaust hole (<NUM>), and
a tip (432A) of the inner wall (<NUM>) in a down direction is formed at a position lower than the vent hole (<NUM>),
wherein the inner wall (<NUM>) is an exhaust tubular wall (<NUM>) of a tubular shape protruding from the facing wall (<NUM>) toward the exhaust hole (<NUM>).